ML072060405
| ML072060405 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/01/2005 |
| From: | Buchsbaum R, Pederson J, Robinson W Massachusetts Audubon Society, Massachusetts Institute of Technology (MIT), Univ of Massachusetts-Boston |
| To: | Office of Nuclear Reactor Regulation |
| Davis J NRR/DLR/REBB, 415-3835 | |
| Shared Package | |
| ML072060321 | List:
|
| References | |
| Download: ML072060405 (187) | |
Text
{{#Wiki_filter:The Dec ine of Fisheries, Resources in ew Engl and
- 4
-1 4 atatn tem.~ et-al I
The Decline of Fisheries Resources in New England Evaluating the Impact of Overfishing, Contamination, and Habitat Degradation Edited by Robert Buchsbaum Massachusetts Audubon Society Judith Pederson Massachusetts Institute of Technology William E. Robinson University of Massachusetts, Boston MIT Sea Grant College Program Massachusetts Institute of Technology Cambridge, Massachusetts
Published by the MIT Sea Grant College Program 292 Main Street, E38-300 Cambridge, Massachusetts 02139 http://web.iiit.edu/seagrant Acknowledgment: Sponsor, Massachusetts Bays National Estuary Program Publication of this volume is supported by the National Oceanic and Atmospheric Association contract no.: NA86RGO074. Copyright ©2005 by the Massachusetts Institute of Technology. All rights reserved. This publication may not be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise without written permission of the holder. In order to photocopy any work fi'om this publication legally, you need to obtain permission from the Massachusetts Institute of Technology lor the copyright clearance of this publication. Design and production by Gayle Sherman Cover photo credits: firont cover, background, rocky coast: Judith Pederson alewifes: Robert Buchsbaum lobster: Robert Steneck harvested scallops, fishing net, and back cover, fishing boats: Madeleine Hall-Arber The Decline of Fisheries Resources in New England: Evaluating the Impact of Overfishing, Contamination, and Habitat Degradation Edited by Robert Buchsbaum, Judith Pederson, and William E. Robinson MIT Sea Grant College Program Publication No. 05-5
We dedicate this book to our colleague, John Alforing, who was a fireless advocate.fbr the health of our fisheries in the marine environment.
Acknowledgments We appreciate the encouragement and the financial support provided by the Massachusetts Bays Program (MBP). part of the National Estuary Program of the United States Environmental Protection Agency. This work was sponsored by a MBP grant, and the original concept came from their Technical Advisory Committee. In particular, we thank Jan P. Smith, Director of the MBP. for helping Its to develop the vision for this project and 1 or supporting Lis as the project unfolded. We also sincerely thank the many reviewers who volunteered their time and energy to critique each of the chapters of the book at various stages and for their valuable suggestions and advice. These include Peter Auster, Mark Chandlei, Michael Dadswell, Ellie Dorsey, Michael Fogarty, David Franz, Madeleine Hall-Arber, Gareth Harding, Boyd Kynard, Sandra Macfarlane, Jack Pearce, Jack Schwartz, Jail Snmith, Peter Wells, Christine Werme, Robert Whitlatch, and several anonymous reviewers. We especially thank our authors for each of their contributions, and, in addition, for their patience as we moved the process of publishing this book along. Finally, the publication of this work at MIT Sea Grant would not have been possible without the dedication and persistence of Gayle Sherman., who transformed all the raw manuscripts into a professional publication.
Contents Preface iv I. Contamination. Habitat Degradation. Overfishing - An "Either-Or" Debate? William E. Robinson and. Iclilh Pederson I1. The New England Groundfish Resource: A History of Population Change in Relation to Harvesting I1 Steven A. Muracnski III Recent Trends in Anadromous Fishes 25 John */foring IV. Pollutant Effects upon Cod, Haddock, Pollock, and Flounder of the Inshore Fisheries of Massachusetts andCape Cod Bays 43 Frederick P Thurber* and Edith Gould V. The Effect of Habitat Loss and Degradation on Fisheries 67 Linda,4. Deeg"n and Rohert Bnchsbauun VI. Effects of Natural Mortality and Harvesting on Inshore Bivalve Population Trends 97 Diane. Brousseau VII. Biological Effects of Contaminants on Marine Shellfish and Implications for Monitoring Population Impacts 119 Judith E. McDowell VIII. Are We Overfishing the American Lobster? Some Biological Perspectives 131 Robert S. Steneck IX. The Role of Overfishing, Pollution, and Habitat Degradation on Marine Fish and Shellfish Populations of New England: Summary and Conclusions 149 Robert Buchsbaum X. Management Implications: Looking Ahead 163 Judith Pederson and William E. Robinson
iv Preface First Preface (2001) This book emerged from one of several issue papers sponsored by the Technical Advisory Committee of the Massachusetts Bays Program, one of tile National Estuary Programs funded by the Environmental Protection Agency. When we started this project, the crisis in New England groundfish populations was not nearly as much in the public consciousness as it is now. There was a fair amount of conjecture within the fishing industry, due in part to uncertainty that exists in stock assessment, concern about pollution and habitat impacts, and anecdotal descriptions of improved fish catch that seemed at odds with agency predic-tions as to the root cause of the problem. We thought it useful to put together a volume that examined the scientific evidence for effects of three major factors overfishing, pollution,. and habitat degradation on northeast finfish, lobsters, and shellfish populations. This approach omits the socio-econoinic drivers which infIluence fisheries management decisions and the industry's perception of the ecosystem. We acknowledge the importance of these factors in the broader scope of the issue. however without a sound scientific knowledge, achieving sustainability in fisheries will falter. During the intervening years since we began the project, the public became increasingly aware of the seriousness of the crisis through numerous newspaper articles, scientific publications, public forums, and political activities. The closure of large parts of Georges Bank to groundfishing, and the recent passage by the New England Fishery Management Council of measures to further reduce fishing mortality focused much attention on the effect that overfishing may have on marine ecosys-tems and the fishing communities that depend on those ecosystems. The cause of fish population declines,-the rate and extent of recovery, and approach to management are still debated. The use-fulness of examining the declines in certain species of commercially important fish,.Iobsters, and shell-fish by taking multiple factors into consideration is compelling because it represents a holistic approach to managing fisheries and addresses management needs into the future. Each of the authors was asked to review the latest scientific information on either overfishing, pollution, habitat degradation, or the relationship among all three variables, on fish, lobsters, or shellfish, particularly as it relates to the Massachutsetts Bays region. Authors were encour-aged to think broadly and to give some sense of the relative impacts oil fisheries of the factors they examined in detail compared to those attributable to other causes. They were also asked to identify. data gaps and to suggest needed research. M~anagemnent implications were then addressed in the final chapter. Robert Buchsbaum Judith Pederson William E. Robinson
- J,niar~tv 2-001 Second lPreqjice (2004).
Since we first assembled the draft contributions of our authors into this volumne and penned the above Preface in early 2001. high profile lawsuits have changed implementation of fisheries manage-inent. Significant changes in fisheries stocks and fisheries management have influenced our overall approach to using and managing our marine envi-ronment. Some trends in fish population recovery appear favorable, whereas others are not quite so optimistic. While not universal, a number of 'improve-ments have been documented in various fishery stocks. Probably the most notable change is in the northeast ground fishery, where several species pop-ulations have increased as a result of the drastic measures implemented to reduce fishing pressure (e. g. closure areas, severe restrictions in the number of days a fisherman can fish). The National Oceanic and Atmospheric Administration's (NOAA's) annual reports to Congress on the
- 'Status of the Fisheries of the U.S." have indicated an overall improvement in groundlish stocks, as evidenced by the stock assessment data collected in 2000, 2001, 2002, and 2003. When we started this work, over 70% of New England groundfish were classified by the National Marine Fisheries Service (NMFS) as overfished (NOAA, 1995). Status of the Fisheries Resources off the Northeastern United States for 1994. NOAA Tech. Memorandum NMFS-NE-108. National Marine Fisheries Service.,
Woods Hole, MA. 140 pp.). The percentage now is about 30% (NMFS, 2001. Report to Congress. Status of Fisheries of the United States. NMFS, NOAA, Silver Spring, MD. 127 p.). An exception-ally good cod spawn in the Gulf of Maine in 1998, combined with restricted fishing effort, has led to the recent surge in the numbers of legal size fish that have been caught (although cod quotas have sometimes prevented the landing and sale of these fish). Nevertheless, groundfish stocks, while increasing as a result of less overfishing, are still nowhere near their historic high numbers and some would argue they are not sustainable. In NOAA's most recent status report (16 June 2004), the Northeast groundfishery was still considered the national fishery in the most trouble. TI welve stocks were still listed as "overfished" (i.e. overall biomass below a set level), and eight stocks were still subjected to "overfishing" (i.e. toomany fish taken). A remarkable recovery has occurred in North Atlantic Swordfish stocks. While the fishery is still at approximately 65% of maximum sustainable yield, stocks have rebounded in an incredibly short time, due primarily to the restrictive international quotas and minimum sizes imposed by the International Commission for the Conservation of Atlantic Tunas in 1997, the imposition of Individual Transferable Quotas (ITQs) by Spain in 1999, and the closure of critical nursery areas to longline fishing by the U.S. in 2000 (NOAA, 2002. http://www.publicaffairs.noaa.gov/releases2002/oct 02/noaa0213 l.html; Garza-Gil et al., 2003. Mar. Policy 27:31-37). Debate continues over Maine's native salmon populations, even while their numbers remain per-ilously low. In June 2004, the draft Federal plan was released by the Atlantic Salmon Commission to save the endangered Atlantic salmon in eight Maine rivers. But the loss of habitat, uncertainty in the primary cause of mortality, and small wild pop-ulations may limit a successful comeback to a thriving fishery. The story with lobsters is mixed. Lobster popu-lations have drastically fallen in southern New England, with a concern that the same trend may be about to happen throughout the region. An arti-cle in the December 2004 Commercial Fisheries News reported that Maine's lobster landings have remained "relatively high" (yet down from 2002), although landings have fallen precipitously in other states. A recent Cape Cod Times editorial (28 June 2003) reported that 91% of the lobsters taken from Cape Cod Bay north to the New Hampshire border were barely of legal size, a trend that highlights growth overfishing and does not bode well for sus-taining this fishery. Nevetlheless, questions continue to be raised as to whether the lobster decline is due to pollution, habitat degradation, or disease, rather than simply to overfishing. The declines in the southern part of New England are further compli-cated by two different types of diseases, one of which may be related to rising temperatures. Some attribute the lack of collapse in Maine waters to community management of the fishery, but recog-nize that increases in landings are due to other fac-tors (Deitz, 2003. Science 302:1907-1912). Fluctuations and trends in bivalve stocks con-tinue to be difficult to assess. Recent advances in high resolution video surveying of scallop popula-tions (Stokesbury, 2002. Trans. Am. Fish. Soc..131: 1081-1092) have led to a proposal for rolling open-ings of different areas of offshore scallop grounds. It remains to be seen whether the rolling opening approach will lead to a sustainable fishery as fish-ermen put pressure on management to open any productive area left unfished. Outside influences may further complicate analysis of success. The recent presence of an aggressive sea squirt, Dideinnum sp. that covers 80% of approximately 75 km 2 of prime scallop beds on Georges Bank adds another dimension to habitat degradation and is one for which we have little experience or knowledge. Shellfish are also at risk. An outbreak of disease
vi (i.e. a parasitic infection Quahog Parasite Unknown or QPX) in southern New England qua-hogs has recently decimated quahog populations in Wellfleet Massachusetts, as it did in Provincetown Massachusetts in 1995. It is not known whether pollution, habitat degradation or even climate change has led to physiological stress that weakens .animals enough to allow parasitic infection to take hold. Fisheries management debates in the northeast have remained as contentious as ever, and possibly more so! The passage of the federal Sustainable Fisheries Act (SFA) in 1996. with its mandated call for revised definitions' of what "overfished" means and its attention to essential fish habitat, led to a great deal of debate (and little initial action) as to how to incorporate these mandates into the region's groundfisheries management plans. The perceived slow federal action led the Conservation Law Foundation, National Audubon Society and the National Defense Council to file a lawsuit in May 2000 against the Commerce Department and its agencies, NOAA and the National Marine Fisheries Service, ftor not doing enough to prevent overfishing of Northeast groundfish stocks or to reduce bycatch mortality when it approved Framework Adjustment 33 to the Northeast Multispecies Fishery Management Plan. The suit alleged that the Adjustment did not comply with the SFA because it based its recom in endations on the Amendment 7 building plan rather than the more stringent Amendment 9 plan, and that even Amendment 9 failed to reduce bycatch. On 28 December 2001, District Court Judge Gladys Kessler ruled in favor of the three conservation groups, and asked both the plaintiffs and defen-dants to propose remedies for her consideration. While each side opposed the other's plan, the two groups forged a negotiated settlement and sent it to the court on 22 April 2002. Four days later, Judge Kessler rejected the compromise plan, and instead handed down a stunning "remedial order" that included area closures and drastic reductions in allowable days at sea. What followed was a tremendous outcry by fishermen, their political representatives and several of the parties to the case, all of whom asked the Judge to reconsider her decision. On 23 May 2002, Judge Kessler granted the motions to reconsider, vacated her 26 April order, and replaced it with the compromise settlement that had been worked out by the parties in the case.. This action did not end the courts involvement in Northeast ground fisheries m anage-ment, however. Just after Amendment 13 to the Northeast Multispecies Fishery Management Plan went into effect on I May 2004, suits were filed in U.S. District Court by both fisherman and conser-vation groups. The Trawlers Survival Fund, a fish-erman's group from Fairhaven, alleged that NMFS made illegal changes to the final rule implementing Amendment 13 that would be detrimental to fisher-men. On the other side, the Conservation Law Foundation and the National Resources Defense Fund filed briefs alleging that Amendment 13 will not stop overfishing, and Oceana filed two lawsuits alleging that Amendment 13 ignores essential fish habitat. All of these contentious legal battles and drastic reductions in both the areas where fishermen are allowed to fish and in the number of days that they are allowed to fish occurred against the backdrop of the recovering groundfish stock. Throughout this time period, fishermen repeatedly questioned why.additional harsh measures have to be imple-mented when the overall trends are improving. They argue that mandating a particular stock recovery in a five year time span is both unrealistic and economically disastrous to the fishing industry. To make matters even worse, in September 2002 NMFS acknowledged that otter trawl lines on the R/V Albatross IV that had inadvertently been mis-matched in length since February 2000 may have led to mistakes in assessing groundfish populations off of New England. While they later provided evi-dence to show that this mismatch did not lead to any significant changes in the stock assessments, fishermen nevertheless maintained that the stock numbers were underestimated and therefore unreli-able for use in management decisions. The per-spective of the New England fishermen and man-agement is in contrast to the Northwest fisheries where scientific advice and stringent measures are more readily accepted. What seems clear today, is that overfishing has been reduced, yet a number of stocks are still considered overfished. In addition, stock abundances, while increasing, have yet to reach their historically, high numbers. There are three issues that are hurdles for broad support of
VII stringent management options. First. uncertainty is a strong Component of stock assessment, which confounds projections of stock biomass. Secondly, the past approach to managing single stocks has failed to sustain some stocks, but currently there are no acceptable models for managers to imple-ment. NOAA and other agencies are focusing on ecosystem management, but this science is in its infancy and without higher levels of certainty, fish-eries management approaches will not be readily accepted by the industry. The original premises that we based this book on - that overfishing. habitat degradation and con-tamination each contribute to the health of our fish and shellfish populations (albeit to different degrees in each fisheries stock); that each of these three impacts has been studied independently by disciplinary scientists, in isolation from each other; that we need to consider each of these three impacts together, in an interdisciplinary holistic approach, in order to understand the total stress on commercially important fish stocks; that we need to place more reliance on a precautionary approach. adaptive management efforts and ecosvstem--based management in order to manage our fisheries popu-lations in a sustainable manner - have been reem-phasized many times.over the intervening years. Many of the specific points.that we made in 2001 have independently been raised since then: " In a recent paper by Giulio Pontecorvo (2003. Marine Policy 27: 69-73), the "'insularity of sci-entific disciplines" was identified as a signifi-cant impediment to fishery management. " There is an increasing awareness that current fisheries practices worldwide are not sustainable (e.g. Myers and Worm, 2003. Nature 423: 280-283; Pauly et al., 2002. Nature 418: 689-695). Approximately 30% of worldwide fish stocks are depleted, overfished or slowly recovering and 44% are currently being fished at or near their sustainable yields (National Research Cotincil. 1999. Sustaining Marine Fisheries. National Academy Press, Washington D.C.).
- Ecosystem-based management (EBM) and the use of Adaptive Management have been endorsed by the United Nations Food and AgriculttIre Organization (FAO), the European Union, and the National Research Council (NRC). The National Marine Fisheries Service (NMFS)'s 5-year Strategic Plan for Fisheries Research (December 2001) placed ecosystem considerations as a priority in its "new genera-tion'" stock assessments.
" The Ocean Studies Board of the National Research Council of the National Academy, of Sciences released their report Effects of Trawling and Dredging oii Seafloor Habitat in May 2002. which concluded that negative effects seafloor habitat were happening'in some areas, and that sufficient data were available to at least conduct preliminary assessments of trawling/dredging in other areas. " Some scientists have advocated against basing fisheries management on Maximum Sustainable Yield (MSY). Richard Zabel and colleagues, for example, have suggested that we now address what he has termed ~Ecologically Sustainable Yield" (2003. Am. Scient. 91: 150-157). This concept recognizes that single species cannot adequately be managed in isolation, but.must be managed as an ecosystem. " The importance of climate change on long-term fisheries trends has now been recognized. Range shifts of New England. marine fish in response to ongoing warmer seawater temperatures had already been documented (Murawski, 1993. Trans Amer. Fisheries Soc. 122: 657-658), and this trend will continue, perhaps in a more accel-erated rate, in the future for species like cod (Scavia et al., 2002. Estuaries 25: 149-164). The failure of the Canadian cod stocks to rebound after their collapse in the late 19940s, even though fishing pressure, has been eliminated, may be of a changing climate. Scavia et al. also predict changes in phytoplankton-zooplankton dynamics that could alter the food sources for fish. Based on mesocosm experiments and examination of short term temperature varia-tions, the US Global Climate Change Research Program predicts that global warming will be detrimental to populations of winter flounder in southern New England (New England Regional Assessment Group, 2001. Preparing for a
viii Changing Climate: the Potential Consequences of Climate Variabilitv and Changie. New England Regional Overview. U.S. Global Change Research Program, Univ. of New Htampshire. 96 pp.) Although its impact has yet to be specifically documented, the spread of lob-ster shell disease and the quahog parasitic infec-tion QPX northward may be linked to gYlobal cli-mate change.
- In January 2005, EPA will release its National Coastal Conditions Report, in which it desig-
/ nates the Northeast as "one of nations dirtiest regions." Finally, both of the two major, recent and long-awaited, reports on the state of our oceans and marine environment, the Pew Ocean Commissions America's Living Oceans. Charting a Course of Sea Change (May 2003) and the U.S. Commission on Ocean Policy's An Ocean Blueprint for the 2 1st Century (Sept 2004) highlighted overfishing. contamination and habitat alterations (direct impacts such as by trawling and loss of nursery areas. and indirect .impacts due to eutrophication, invasive species, to name a few) as all being important contribu-tors to our marine resource declines,.and called for an ecosystem-based management approach. Both reports can be summed up in the words of the Chairman of the U.S. Commission on Ocean Policy: The oceans and the coasts are in trouble, and we need to change the way we man-age them. - Janes D. Watkins, 2004 We are pleased that our original premises for this book have now been more broadly accepted by the scientific community. When we initiated this project, many voiced skepticism that overfishing, habitat degradation and contamination could each have a role to play in the health of otIr many fish-ery stocks, and. even if they did, whether we could make useful comparisons of the impact of overfish-ing, habitat degradation and contamination on fish-eries stocks. We believe that the information that our authors have summarized and reviewed clearly demonstrates that each of these three impacts can be significant, although the data are not yet avail-able in most cases to estimate the degree to which each of the three operates. We thank the Massachusetts Bays Program for providing the initial funding for this project. We also thank otIr authors for sharing ouIr vision, and for their patience as we worked to bring this book to publication. We also thank the many reviewers who read the chapters and whose thoughtful insights strengthened this work. (They are acknowledged in each chapter.) Given the per-ceived restricted audience that this volume Would likely attract, publishers proved illusive. We sin-cerely thank MIT Sea Grant for taking up our cause and publishing this work. Weare all the more grateful in that MIT Sea Grant agreed to publishing it "'on the web", making its distribution and hope-fully its impact much more widespread and easily accessible. Finally, we would like to thank you, our readers, who will have the ultimate vote on whether our work proves useful in advancing the. ongoing debate on fisheries management. Robert Buchsbaum Judith Pederson William E. Robinson December 2004
CON 1.0 1 f.NA I I (IN, HA 111 FAI D1_(iR A D A I ION, O\\ ERHS I I I NG D FIB A I-F Chapter I Contamination, Habitat Degradation, Overfishing - An "Either-Or" Debate? WILI.IAM E. ROBINSON UniiversiO" of Kassachusells Boston Delpartment of Envirornineental, Eart/h and Ocean Sciences (EEOS) 100 Morrissey Blvc. Boston. 1/1 02125 US.4 .1 UDII PvIMLRSON !I'iassoch/iiie.s his.liftcl' q TeLchnology Sea Grant College Prograin 292 Main Street. E38-300 Cambridge, MA 02139 USA Fish are good for the heart, but such knowlectke will soon he of/itllte use if/we cut the heart out oj/lhe ocean. -Derrick Z Jackson, Columnist Boston Globe, 14 Jan 1998 INIIROI)UCIION A great number of nearshore and offshore fish-ery stocks have deteriorated throughout the Northeast over the past 30 years. The most visible example of this decline was the precipitous drop in populations of groundfish (benthic-feeding fish such as Atlantic cod (Gadus mohrua), yellowtail flounder (Pleuronectesferrroginetus) and haddock (A/elanogrannnus aegle/inius)) (NOAA, 1998; NEFSC, 2000). These stocks were severely over-fished by foreign fishing fleets in the 1960s and early 1970s, and then partially recovered in the mid-1970s, coincidentally with the implementation of the Magnuson Fishery Conservation and Management Act (Magnuson Act) of 1976. The overall decline of most of these groundfish species eventually resumed, and has continued up to the present time (Figure 1. 1; NOAA, 1998; NEFSC, 2000). With recent stringent management measures, some stocks appear to be showing signs of recovery. but they are still nowhere near their former levels of abundance (NEFSC, 2000). This decline notwithstanding, groundfishing has remained an important contributor to the overall northwest Atlanlic (-Northeast) fishery (Figure 1.2), accounting lor an average of 121.000 metric tons of landings and approximately $179,000,000 in ex-vessel value .for the years 1993-97 (NOAA, 1998). When con-sidering.finfish landings alone for this period of time, the groundfishery provided approximately 24% of the total finfish catch in the Northeast, yet accounted for 55% of the ex-vessel value for the total landed finfish (NOAA 1998). The recent crisis in the groundfishery, which has been steadily unfolding since the enactment of the Magnuson Act in 1976, was highlighted in Massachusetts with the publication of the Assessment at Mid-Decade (MA DMF, 1985). Warnings have been issued repeatedly ever since (OGTF, 1990; NEFMC, 1991, 1994, 1996, 1999, 2000; Doeringer and Terkla, 1995; Murawski et al., 2000). Stocks had plummeted to such a point by 1991 that the Conservation Law Foundation and the Massachusetts Audubon Society filed a lawsuit against the New England Fishery Management
R O'lBINS(ON & PI-RSON .50..........................l'... ""t"":'f+'+l """flu+[ ' A. B. Principal Grund fish & Fiour~de.'s anlindroiunous Hm'cllhratc, 60 030 H) .30 - -0 'it 20 10 jill cioIinaic peai 2170 40 [ Abundance Landings Vý' 131 HI CO (r d fish1 1211 C. D. 38(1 98 ýdo 46 200 100 121 glun l h A.
- 0.
r---r-v--- H.. r T-0 60 6-3 66 69 72 75 78 81 184 37 90 93 96 )ear Figure I.]. Trends in abundance and commercial land-ings (U.S. and foreign fleets) of principal groundfish from the noitheastern United States. (Figure from NOAA, 1998). Council (NEFMC) for failure to prevent overfishing. This resulted in the promulgation of Amendment V to the Northeast Multispecies Fishery Management Plan and an emergency closure of parts of Georges Bank in 1994 (NEFMC, 1994). Since stocks did not rebound as anticipated, additional amendments and framework adjustments were issued, closing large areas to fishing and severely curtailing the number of allowable days-at-sea (NEFMC, 1996; 2000). The reauthorizatibn of the Magnuson Act, the Sustainable Fisheries Act (SFA) of 1996, imposed new requirements, including: (I) regular reporting of the status of individual fish stocks, (2) revised overfishing definitions, and (3) recovery plans for overfished stocks that included delineating and conserving essential fish habitat. These restric-tive measures are having an inordinate impact on the economic and social well-being of our fishing communities. While groundfisheries have received the most public attention, other commercially important fish and shellfish species have also dwindled in num-bers. Bluefish (Pomatomnus salatrix) stock biomass has shown a downturn over the past nineteen years following a peak in total east coast landings in Figure 1.2. Mean Northeast fishery landings (thousand metric tons; A, C) and ex-vessel value (millions of dol-lars; B, D) for the years 1993 - 97. A and B include fin-fish, shellfish and other invertebrates; C and D include only finfish. All data firom NOAA (1998). 1981 (NOAA, 1998). Stock biomass fell far beloxv densities needed to maintain maximum sustainable yield (MSY) (e.g., only 21% of MSY in 1997; NOAA, 1998): The 1999 Atlantic bluefin tuna (Thunnus thynnus) spawning stock biomass was approximately 16% of the 1975 level, and only 3 1% of the level needed to achieve MSY (NMFS, 1999). There are indications that soft-shell clam (A ya arenaria) and quahog (lf'er'enarict nerc'enar-ia) populations have declined in some locales (Alber, 1987; Matthiessen, 1992; MacKenzie and McLaughlin, 2000) and several anadromous fish (alewife, Alosa pseudoharengus; blueback herring Alosa aestihalis; Atlantic salnon, Salno salar; and American shad, Alosa sapidissima) are exhibiting all-time low population numbers (NOAA, 1998). The situation became so serious for the wild stock of Atlantic salmon that the Gulf of Maine popula-tion was proposed for protection by the Endangered Species Act (Fed. Reg., 1999). Finally, there is fear that the lobster (Hoinarus americanus) spawning biomass may also be declining even though lob-sters have been harvested in record numbers for almost a decade (NOAA, 1998; McBride and Hoopes, 2000). Fisheries managers are concerned that if environmental conditions become unfavorable,
CONTAMINAI [ON. 11ABIFAT DEGKADAMIN, OVERFISHING D1711AH7 the lobster population will not be able to sustain current catch efforts. Not all species of fish and shellfish are exhibit-ing an unequivocal decline in numbers. Sea scal-lops ([lacopecten magellanic'us), while considered by National Marine Fisheries Service to be overex-ploited, exhibit "'boom and bust" years, dictated by inconsistent and unpredictable cycles of recruitment and fishing pressure (NOAA, 1998; Taylor, 1998). Striped bass (Morone saxatilis) suffered from over-fishing and poor recruitment, but have rebounded following Northeast cooperative fishing bans initi-ated in 1982 (NOAA, 1998). Species, such as mackerel (Scomber scombrus) and Atlantic herring (C'upea harengus), that are not sought after inten-sively by the fishing industry, have increased in numbers over the past decade (NOAA, 1998). The Northeast fisheries are not unique. While the unrestricted exploitation of Georges Bank fish stocks by foreign fishing vessels in the 1960s and 1970s resulted in the passage of the 1976 Magnuson Act, U.S. vessels quickly entered the fishery to resume the same trend of overexploita-tion. This regional decline in fish populations is similar to what is occurring in many other regions of the United States and throughout the world (FAO, 1997; Pauly et al., 1998; Christen, 1999). The reductions, however, are particularly evident and well-documented, here in the Northeast. PUBLIC PERCEP'IONS Appearances can be deceiving. - (Anon. proverb) What is the major anthropogenic cause of the stock declines in the Northeast fisheries-overfish-ing, introduction of contaminants, or habitat degra-dation? The public is regularly barraged with alarming news reports on the collapse of ourt fishing industry, coastal and marine habitat degradation, bacterial contamination of our inshore shellfish species, and toxic chemicals in the marine environ-ment. Can declines in fish stocks be attributed largely to one of these factors or is it their interac-tions that are of the greatest consequence? In this work each of the human-induced impacts-overfishing, contamination, and habitat alteration---is examined and discussed as to their relative importance to selected fish and shellfish stocks. OVERFISHING The cod has symbolized fisheries in Massachusetts and New England since the time of the Basque fishermen who startedbringing New England salted cod back to Europe as early as the 1400s. Initial reports of explorers and European colonists describe an unlimited abundance of cod and other fish in New England waters. Impressive catches were recorded throughout the 19th century: The bankers, particulaHy if the fishing w, as good, would have to row back to the schooner with a dorifild of zup to. 1800 pounds five or six times to finish with a single trawl, hollering 'Dory!" as. they bumped pq) alongside, bringing skiplper and cook running to the i-ail. Joseph E. Garland. 1983 The first indication to the public that something was seriously awry with New England fisheries was probably in the 1980s when fish prices rose and newspapers began to report the plight of fisher-men no longer able to make a living catching fish. What has put us in the situation where two-thirds of the Northeast commercial fish stocks are now designated as overexploited and 59% of these stocks are categorized as having "low abudance" (Table 1.1; NOAA, 1998; NEFSC, 2000)? Over the past 100 years, the fishing industry has undergone major changes-from fishing in wooden boats under sail, to steam engines, to diesel-powered steel-hull trawlers, and even to factory ships that process seafood at sea. Improved methods of locat-ing and catching large concentrations. of fish have increased the efficiency of fish harvesting (although catch-per-unit-effort has now decreased due to the declining biomass of targeted species). For years, fisheries scientists carrying out stock assessments have warned that unregulated fishing would eventually lead to stock declines:
4 I{O[I Ný(N &ý N'FIES0N. Excessive.fishing has lec lo significantly reduced resource abundance, snmaller and less fish cad shel/Jish being landed in our ports, adcl economic harc/'hil).foi the st /ate's. fishging ihchIstso. - MlA DMiF 1985 There is a general consensus among fisheries managers that the effects caused by overfishing have far outweighed the adverse impacts caused by contaminants and habitat loss, at least with respect to recent groundfish declines (Werme and Breteler, 1983: Cohen and Langton, 1992: Serchuk et al., 1994; Myers et al., 1995). Simply stated, their position is that overfishing has reduced our stocks of ground-fish to levels that cannot support sustainable yields at current landings. A number of fishermen agree that overfishing is a cause of groundfish stock depletion, but also cite habitat degradation, poilu-tion and natural weather events as important ifactors (Dorsey and Pederson, 1998; Pederson and Hall-Arber, 1999). Sea scallops and lobsters are also listed by NMFS as overexploited, but nearshore shellfish and anadromous fish are not as easily characterized. As discussed more fully in the fol-lowing chapters, the real or perceived importance of overfishing depends to a large extent on the species, its various subpopulations (if any), the subregion in question, and the availability of data. Table 1. 1. Stock abundance and level of exploitation for 51 Northeast finfish and invertebrate fisheries. Percentages refer to the total number of stocks in each category. Data taken from NOAA, 1998. SNE = Southern New England; GB = Georges Bank: I.S = Long Island Sound: GM = Gulf of Maine, S. - Southern: N. = Northern. Level of Underexploited Fully Exploited Overexploited Abundance (10% of all stocks) (24% of all stocks) (66% of all stocks) I-I igh (10%) M~ediumn (3 1%) Atlantic herring Atlantic mackerel (4%) Atlantic surfclamn Butterfish N. Red hake (6%) Striped bass (2%) Longfin inshore squid Ocean quahog Northern shortfin squid Skates N. Windowpane flounder (10%) Am lobster - GM Spiny dogfish (4%) Summer flounder Am. lobster - GB+S, SNE-LIS N. Silver hake Yellowtail flounder-Cape Cod Am. Plaice Winter flounder - GB Northern shrimp (15%) Scup, Black Sea Bass, Sea scallop Cod-GB, GM Witch, Cusk, Tilefish, Wolffish, Goosefish, Bluefish White hake, Ocean pout Yellowtail flounder - Mid-Atlantic River herring Haddock - GM S. Silver hake, S. Red hake Atl. Sturgeon, Shortnose Sturgeon S. Windowpane, AtI. Salmon Winter flounder - SNE-MA, GM (47%) Low (59%) (0%) Haddock-GB Yellowtail flounder-SNE Redfish Pollock American Shad Yellowtail flounder - GB (12%)
('ONFANIINAIlON, HFABITAT*\\ [I RAI)ATION, O\\'ERHISillNG [)EB.\\TE CONTAMNINATION Another factor that is often identified as a cul-prit responsible for declining fish populations is the impact of chemical contaminants-those chemicals that enter the environninent from land-based, human activities. Are these chemicals having an impact on fish populations? The answer is far from simple. Numerous studies have documented the pres-ence of a wide range of chemical toxicants (Dow and Braasch, 1996; Jones et al., 1997; NOAA/NS&T, 2000), including those listed as _priority pollutants" by the U.S. Environmental Protection Agency (EPA, 1991), in waters, sediments and the tissues of our fishery resources. Nevertheless, few of these priority pollutants, and almost none of the approximately 65.000 to 75+000 substances in commercial use today, have been rou-tinely monitored in commercial species. Based on studies of contaminants in marine sediments and nIarine Mussels (Buchholtz ten Brink et al., 1996; Jones et al., 1997), a number of urban harbors in the Northeast (Boston, Salem and New Bedford Harbors in Massachusetts; Hudson-Raritan Bay in New York/New Jersey; western Long Island Sound in Connecticut; Portsmouth NH Naval Shipyard) have been identified as containinant "hot spots". In general., organisms more distant from these hot spots (e.g. offshore organisms) contain lower levels of contaminants than animals more immediately exposed (McDowell, 1996). Our concern over chemical contaminants often focuses on human health. Reports of elevated con-centrations of contaminants in commercial fish or shellfish almost always raise questions of human health impacts. For example, Murchelano and Wolke (1985) described tumors in winter flounder (Pseudoplewronectes amnericanus) collected in 1984-85 from areas in Boston Harbor MA, includ-ing an area near a sewage outfall on Deer Island Flats. While raising awareness of contaminant effects on individual organisms, their study invoked concerns by the news media of a possible link to human cancer. Similarly, the U.S. Environmental Protection Agency's Quincy Bay, MA study (EPA, 1988; Cooper et al., 1991) brought attention to high levels of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydro-carbons (PAHs) in lobsters, soft-shell clams, and winter flounder. This raised fears of human neurological and carcinogenic impacts, and resulted in the issuance of a public health advisory that is still in effect today (MA DPH 1988). In addition, the widespread distribution of mercury in the northeast from minid-western coal-fired power plants and incinerators has resulted in the bioaccumula-tion of methyl-mercury in the aquatic food webs (Pilgrini et al., 2000). H-umminan health advisories have been issued. owing to mercury's neurotoxic effects, particularly in developing children. While most of this concern has focused on mercury bioac-cumulation in freshwater fish caught by recreation-al anglers, a variety ofestuarine fish and shellfish that are commonly used for human consumption have also been found to contain elevated nmethyl-mercury levels (Burger et al., 1998; Kawaguchi et al., 1999; GilhnoLIr and Riedel, 2000). Although the most widely publicized contami-nation concerns address human health issues, a number of studies have directly examined the effects of contaminants on the health of marine organisms. While the linkage between contaminants and the health of marine populations is difficult to establish conclusively, pollution has been implicated as a factor in several fishery declines (Goodyear, 1985; Barnthouse et al., 1990) and even in large-scale ecological perturbations (Sarokin and Schulkin 1992). Many more studies that integrate chemical concentrations in water, sediment and tis-sues Wvith adverse physiological effects, and that ultimately document the effects of contaminants on populations, are clearly needed. As is evident in the chapters reviewing effects of contaminants on fin-fish and shellfish, the investigation of contaminant impacts on populations is one of the most pressing needs for future research, particularly for stressed populations. HABI'rAr DEGRADATrION Degradation of marine and estuarine habitats is also perceived as harmful to marine resources. This degradation may take many forms, over and above the effects caused by human related chemical con-tamination. Habitat degradation may be caused by physical changes, such as increased suspended sed-iment loading, overshadowing from new piers and wharves, filling coastal wetlands, and trawling and dragging for fish and shellfish. Although often
6ROIUNS(ON & I'I)FI(ISON ignored as a habitat alteration, increased nUtrients froni wastewatei, fertilizers, and atmospheric inputs also degrade habitats, especially those nearshore. The resulting accelerated eutrophication may cause unwanted algal blooms. low dissolved oxygen and altered community composition. Natural dInviron-mental phenomena (e.g. weather, climate) must also be considered in conjunction with these habitat changes (Werme and Breteler, 1983; Serchuk et al., 1994; Hofmann and Powell, 1998). Regardless of whether a habitat alteration is due to natural or anthropogenic causes, it can have a long-term impact on community structure. For example, the extensive die-off of eelgrass beds (Zoslera marina) caused by a disease which struck the East Coast during the 1930s. markedly changed the vacated habitat and the structure of the benMhic food chain, and lead to'sharp declines in bay scallop populations (Orth and Moore, 1983; Short et al., 1986, Buchsbaum, 1992). Some of these changes are still evident today. Otter trawling and scallop dredging also appear to be causing dramatic shifts in benthic community structure due to physical dis-ruption of the bottom, reduction in habitat coin-plexity and direct interference with trophic transfer (Langton et al., 1996; Langton and Auster, 1999). At the far extreme, habitat may be completely lost as a result of coastal development, harbor dredging and offshore mining operations. Nearshore finfish and lobster "nursery grounds" are particularly sus-ceptible to all these types of habitat loss. Understanding these effects and separating physical changes from overfishing is a challenge for scientists, managers and the fishing industry. Some changes, such as building dams, armoring of the shoreline and coastal development have impact-ed shellfish and anadromnous fish, but these impacts are not well documented. The challenge for man-agers in regard to habitat is similar to that for chemical contamination---how localized are the impacts and howv have they effected populations? In the chapter on habitats, the authors review studies that relate habitat alteration, particularly those related to human activities, to effects on populations. Till.: "ErIrttil-AtOlt" 1) E RAT E' Thefiurst step in science is the step).fi'om qualititivc i,)l/IssioC55 /0n q !iantitative mneasurenment. The occasional difjiculty of this task does not lessen its importance. - i.A. Gates, 1978 Given that there are at least three disparate types of impacts on fisheries stocks, the impact of each of these factors is sometimes viewed as an
- either - or" question--
"Is a particular fishery decline due to overfishing, or to contamination, or to habitat degradation?" Scientists are partly to blame for perpetrating this situation, since they have generally avoided investigating these factors simiultaneously. Instead, separate groups of inde-pendently-trained scientists tend to focus on each factor in isolation: fisheries scientists typically deal with fish population assessments and gear issues; aquatic toxicologists with contamination issues; and benthic and estuarine ecologists with changes in habitat and community struicture. As a result, a type of scientific polarization has imnintentionally arisen. A number of researchers have now acknowl-edged the interrelationship between overfishing, pollution and habitat changes (Barnthouse et al., 1987, 1989, 1990; Buchsbaum et al., 199 1; Sinderinann, 1994; Dow and Braasch, 1996). While they have advocated an integrative approach, much of the species-specific information on overfishing, contamination and habitat degradation has yet to be translated into comparable measures and totally integrated. For example, Barnthouse et al. (1987) attempted to express the effects of contamination in the same units as for overfishing, although they did not further expand their study by adding in habitat degradation in the same type of common currency. Novel, integrative techniques need to be devel-oped and applied, if the effects of overfishing, con-tamination, and habitat degradation are to be com-pared. In the past, fisheries nianagers have relied on age-frequency distributions collected during annual stock assessment cruises for assessment of spawning biomass and year class recruitment. Models based on classical population studies were
CONI.VONINAI([ON, HIABIIAI )F(6R.DAIH). ()\\VlRFISHFIN( DiFiAIA 7 then adapted lor fisheries manag ers (see NRC. 1998a, b lbr descriptions and assessment of these models). These used age-frequency and age-fecun-dity distribution patterns and formed the basis for fisheries managers to conclude that overlishing was the main factor affecting fishery stock declines (NOAA, 1998; NRC 1998a, b, 1999). Recently, however, fisheries scientists have developed a num-ber of innovative models to guide fisheries man-agenient decisions as they manage fishing elfort (Sissenwine and Shepherd, 1987; Fogarty et al., 1992; Myers et al.. 1995). These models point out that factors such as environmental change and habitat loss may prevent the recovery of some stocks, such as spring-spawning Icelandic herring (Clupea harengus)and Pacific salmon (Oncoriowuchus spp.; Myers et al., 1995). One type of model, a recruitment overfishing model, allows managers to calculate maximum fishing mortality rates which would still allow sus-tainable harvests (Sissenwine and Shepherd, 1987; Fogarty et al., 1992). It has been adapted in the Northeast Multispecies Fishery Management Plan (NEFMC, 1994). This model, which includes esti-mates of lishing mortality and natural mortality rates, could be modified to includecontaminant-induced and habitat-associated mortality. Aside firom the capture and removal of fish and shellfish, other harvestingcrelated factors must also be considered when assessing fisheries stocks. Juvenile bycatch (pre-recruit individuals of corn-mercially important species) suffer significant mor-talities during all seasons of the year (Robinson et al., 1993; NOAA, 1998). Mortality is particularly severe when deck conditions are most extreme, such as in mid-sumler or mid-winter. This bycatch mortality has not yet been incorporated into fish- .eries management models. Interactions between fish species have also received little attention. Declines in the population of a fished species can have repercussions through-out the community structure. On Georges Bank, for example, the declines in cod, haddock and flatfish were apparently accompanied by an increase in cartilaginous fish numbers. Whereas skates (Raja spp.) and spiny dogfish (Squalus acanthias) accounted for only 25% of the NMFS survey trawl catch in 1963, their proportions increased to nearly 75% in the early 1990s, but has since declined (NOAA, 1998). Total biomass of the system had riemained relatively hiigh, but the biomass of the more cornmercially-valtLable resource species had fallen. Although it now appears that there is no causal connection between the decline in commer-cially important species and the increase in carti-laginous fish biomass (Murawski, Chapter 2), the community structure has nevertheless shifted dra-matically. An ecosystem approach to fisheries man-agement clearly needs to be adapted to ensure sus-tainability (Parsons, 1992-NRC 1999). This is not to say that all of the information is currently at hand to resolve the question of whether overfishing, contamination, or habitat degradation is the most important factor affecting fisheries declines. Data gaps are inherent in all scientific pursuits. Habitat data and contaminant effects on populations are particularly scant. There is a real need to identify these gaps and to recommend studies to fill them. TIlE NEED FOR A Homisrmc APPROACII The whole is ccqtoa[ to the.itsm ol/its parls. - Euclid. 365-300 B.C. The whole is greater than, the saut o/i/s parts. - Gestalt Theory. A1[ Wertheimer, 1924 Expressing the issues of overfishing, contami-nation, and habitat degradation in "either-or" terms has hindered dialogue among fisheries managers, aquatic toxicologists, and benthic ecologists. The question must be rephrased if we are to address it systematically. Rather than examine fish popula-tions in terms of exclusive categories, the more important question is "To what degree do overfish-ing, contamination and habitat degradation each adversely affect our fisheries resources?" We need to develop approaches that allow us to study the interactions among these three, not just examine their effects individually. Each of these factors is a form of stress on a population. Populations stressed by one factor are generally mor( susceptible to additional stresses
8 ROBfINSO'N & I'FIMI~RSON caused by other factors. Goodyear (1985), for example., demonstrated that contaminant exposure can be more deleterious to fish populations that are also subjected to fishing-induced stress. Barnthouse et al. (1990) described a significant interaction between containiniant-induced mortality and fishing mortality in Gulf of Mexico menhaden (Bi-eioo'ica ])a/lno/7ts) and Chesapeake Bay striped bass (for+one saxatilis) populations. Contaminants had little impact on the populations when population levels were high (unexploited populations) but had measurable impacts when populations were low. While-this interaction was rather modest, it demon-strated that overfishing and contaminant effects cannot be viewed as independent issues. We must not overlook the importance of natural environmental variability (both biotic and abiotic factors) and its impact on population and community structure. Often, decadal or multi-decadal cycles of environmental change must be considered in order to umderstand population shifIts (Holmann and Powell, 1998). Longer-term effects, such as climate change and sea level rise, must also be factored in. While environmental variability is certainly of sig-nificance, the importance of fluctuating environ-mental factors in comparison to anthropogenic influences (overfishing, contamination and habitat. destruction) is being debated by the industry, man-agers, and environmental groups. Nevertheless, holistic models must contain provisions for entering changing environmental variables. In the absence of data on cyclic processes, these models must, at the very least, include stochastic functions. Consideration of essential fish habitat has recently been incorporated into fisheries manage-ment plans (Stevenson 1994; NEFMC, 1999). This should result in a more holistic approach to fish-eries management by, in effect, including the inter-actions among overfishing, contamination, habitat loss and natural factors in the decision-making process. The Atlantic States Marine Fishery Commission (ASMFC 1992) conducted an exten-sive analysis of habitat requirements in its Winter Flounder Fishery Management Plan, but it was not until the reauthorization of the Magnuson Act (i.e. the Sustainable Fisheries Act of 1996) that all man-aged species were required to be examined for, habitat needs. The ASMFC went so far as to con-clude that coastal habitat restoration could result in greater long-term benefits to the fishery than simply redtucin g fishig mortal itv. OUR .RIT IN TIM DEIBATE, Our intention with this volume is to examine existing data oin the effects of overfishing, contami-nants, and habitat degradation on various fish stocks in the Northeast. This assessment will, how-ever, have implications for fishery stock manage-ment in areas far beyond those of the Northeast. Our authors offer their perspective on the degree to which overfishing, habitat degradation and contam-inants are affecting Northeast stocks, but are limit-' ed by lack of studies correlating each factor with population impacts-the common currency. One outcome has been to identify research areas where new data are needed in order to improve our esti-mates of the importance of these factors, and to integrate them into a more holistic view. Four types of fisheries will be highlighted in the chapters that follow: groundfisheries, anadro-nnous fisheries, inshore bivalve shellfisheries and the lobster fishery. Each of these fisheries has its own unique blend of the various anthropogenic fac-tors that have impacted their fish populations. These types of fisheries were chosen because of the availability of at least some data on overfishing, contamination, and habitat degradation for each of them. Moring's treatment of anadromous fish (Chapter 3) has come the closest to integrating all three issues within one chapter. The mass of species-specific data on one or more of these three issues has precluded this approach for the other three fisheries. Instead, chapters will address poilu-tion, habitat and overfishing issues separately. Thurberg and Gould (Chapter 4) will highlight the effects of contaminants on groundfish, whereas McDowell (Chapter 7) will cover pollution impacts on shellfish. Murawski (Chapter 2) will address stock assessment and overfishing issues tor the Northeast groundfishery, while Brousseau (Chapter
- 6) will examine inshore bivalve populations, and Steneck (Chapter 8) the lobster fishery. Deegan and Buchsbaum (Chapter 5) will discuss the importance of habitat loss and degradation.
The main goal of this work is to unite the sci-entific energies of fisheries managers, aquatic toxi-cologists, and marine ecologists in order to reach a
.( ON I.AM INAiio10N.fI It ItIiT DIit(;k..ili1irlt, OVE Iti'iF Ittf N G DI~itrl 9 consensus as to the severity of overfishing, contain-ination, and habitat degradation on our fisheries stocks. The data and background presented in Chapters 2 through 8 provide the basis for the sum-marization and evaluation of the relative impor-tance of overfishing, habitat degradation and poi lu-tion for each of these fisheries, as presented by Buchsbaum (Chapter 9). As further discussed in the final chapter (Pederson and Robinson), this holistic approach may challenge fisheries managers to modify the way in which they manage each of the Northeast fisheries. It is our hope that the conclu-sions presented here can then be conveyed to the general public, eliminating at least some of the confusion that currently enshrouds these issues. LITEIRATURE CITED) Alber, M. 1987. Shellfish in Buzzards Bay: A resource assessment. Buzzards Bay Project (BBP-88-02). U.S. Environmental Protection Agency. Boston MA 75 pp. ASMFC (Atlantic States Marine Fisheries Contitlissionlt. 1992 Fishery Managcment Plan for Inshore Winter Flounder. Fisheries Management Report No. 21 and 22. Atlantic States Marine FishCries COnittliiSsiOln, Washingtolt D.C. I3S Pp. plus S pp. addendum. BarnmhousC. L.W.. G.W. Suter II and A.E. Rosen. 1989. Inferring pop-ulatiatn-levCl signilicunCC kiOn iindividuall-lCvCl elfIfcts: iAn extrapolation from fisheries science to ccotoxicology. In: Aquatic Toxicoloyv and Environmental Fate. II th Vol. STP 1007, M. lcwis and G.W. Suter 11, eds. American Society for Testing and Materials. Philidelphia, PA. Pp. 289-300. Barl-thousc, L.W., G.W. Suter II and A.E. Rosen. 1990. Risks of toxic contatttsitants to exploited fish populationIs: liltluencc Of life his-tory, data uncertainty and exploitation intensity. Environ Toxicol. Chem. 9: 297-311. Barnthouse. L.W. G.W. Suter II. AE. Rosen and J.J. Beauchamp 1987. fsttiiiatitg respoises Of fish pOplulatioIs to toxic cottamti-nants. Environ. Toxicol. Chem. 6: 811-824. BuIchtholtz ten Brink, M.R., F.T. Manheim and M.H. Bothner. 1996. Contaminants in the Gutlfof Maine: What's here and should we worry? In: The Health of the GuIlf of Maine Ecosystew: Cumituliative Inpacts of Multiple Stressors. D. Dow and E. Braasch. eds. Regional Association for Research on thle Gulf of Maime (RARGOM) Report 96-1. 30 April 1996. Pp. 91-115. BntCtsbaiut, R. (ed.). 1992. Tuming the Tide: t"oward a Livable Coast in Massachusetts. Massachusetts Audubon Society. Boston, MA. 121 pp. Buchsbaum,,R., N. Maciolek, A. McElroy, W. Robinson and J. Schwartz. 1991. Report of the Living Resources Committee of the Technical Advisory Group for Marine Issues. Report to the Secretary of Environmental Aff[airs, Massachusetts Executive Office otf Environnttttal Affairs, Boston, MA. 15 pp. Burger, J., J. Sanchez and M. Gochifld. 1998. Fishing, consumption, and risk perception in fisherlhlk along atn East Coast estuary. Environ. Res. 77: 25-35. Christen, K. 1999. Sustaining global fish stocks. Environ. Sci. Technol. 33: 452A-457A. Cohen, E.B. and R.W. Langton. 1992. The ecological consequences of fishing in the Gulflof Maine. In: The Gtlfof Maine. NOAA Coastal Ocean Program Regional Synthesis Series Number I. P1p. 45-9). Cooper. C.B.. M.IF. Dwole and K. Kipp. 1991. Risks of consum ptiOn el contatninated scaitohd: The Quincy t 3ay case study. Env' Health Persp 90: 133-140. Doeiiroer. P.IB. and l).G. Tcrkla. 1995. Trouble in Fishing Waters. Bostonia. Spring 1995: 15-21. Dorsey-. F.M atn(l.1. Pederson (eds.). 1998. EIfects of Fishint Gear ott the Sea Floor of New Eniland. Conservation law Fouindation, Bostont. MA. 160 pp. Dow. 1. and V. IBraasch (cds.. 1996. The I ealth of the Gul fio Maine Fcosystem: Cumulative Itnacts of Multiple Stressors. Regional Association fur Research oti the Gulf of MaItmc (RAR-GOMIh Report 06-1/330 April 1996. 181 pp. plus appendices. IPA (Eivirotmiental Protection Agency). 1088. Analysis of Risks fronm Consunption of Quimcv 13ay Fish and Smellfish. Report pre-pared by Mctcalfand Eddy, Inc.. Boston, MA. May 1988. 69 pp. plus appendices. EPA (Envirotlnental Protection Agency). 1991. Water Quality Criteria Summary. UiS Environmental Protection Aecncy, Washington D)C. I pp. FAO (Food and Agriculture Organization). 1997. Review of the State of the World Fishery Resources: Marime Fisheries. FAO Fisheries Cirulair No. 920 1I:RNM/C920. II pp. piLus appelndices. Fed. Reg. (Federal Register). 1999. Endangered and threatened species; Proposed endangered status for a distinct population seg-tnent of anadromous Atlantic salomon (Sa/mtho solar) its the Gulf' of Maine. 17 November 1999. Fed. Reg. 64:62627-62641. Fogarty. I, .I.J. A.A. Rosenberg and M.P. Sisscntinc. 1992. Fisheries risk assessmentt Sources of uncertainty. A case study of Georges Bank haddock. Environ. Sci. Technol 26: 440-447. Garland. I.E. 1983. Down to the Sea: The Fishing Schooners of Gloucester. DR. Godine Publ., Boston, MA. 224 pp. Gates. M.A. 1978. An essay on the principles of ciliate svsteanatics. Trans Alit Slicrosc Soc 97: 221-235. Giliour, C.C. and G.S. Riedel. 2000. A survey of size-specific mercury concentrations in game fish from Maryland fresh and estuarite waters. Arch. Environ. Contamin. Toxicol 39: 53-59. Goodyear, C.P. 1985. Toxic materials, fishing, and environmental variation: Simulated etfects otn striped bass population trends. Trans Am. Fish Soc. 114: 92-96.
- Holisann, t
.E. and T.M.PIowell. 1998. Environmental variability effects on marine fisheries: Four case histories. Ecol. Applications 8 (Suspplement):S23-S32. Jackson, ).Z. 1998. A giood fish story - And a bad one. Boston Goboe. Op-ed page A I5, 14 January 1998 Jones, S.H., M. Chase, J. Sowles, W. Robinson, P. Hennigar, G. Harding, D. Taylor, P. Wells, J. Pederson and K. Coombs. 1997. Tite First Five Years of Gulfwatch, 1991-1995: A Revicaw oftlhe Program and Results. Gulf of Maine Monitoring Committee of the Gulf of Maine Council oni the Marine Einvironiment. I I2 pp. Kawaguchi, T., D. Porter, D. Bishek and B. Jones. 1999. Mercury its the American oyster Crassostuea rirginica Its South Carolina, USA, and public health concerns. Mar. Pollut. Bull. 38: 324-327. Langton, R.W. and P.J. Auister. 1999. Marine fishery and habitat inter-actions: To what extent are fisheries and habitat, interdependent? Fisheries 24: 14-2 1. Langton, R.W.. R.S. Steneck, V. Gotecitas, F. Juanes and P. Lawton. 1996. The interface between fisheries research and habitat man-agement. N. Am. J. Fish. Manage. 16: 1-7. MacKenzie, C.L., Jr. and S.M. McLaughlin. 2000. Life history and habitat observations of softshell clams Aiya arenaria in northeast-ern New Jersey. A. Shellfish Res. 19: 35-41. MA DMF (Massachusetts Division of Marine Fisheries). 1985. Assessment at Mid-Decade: Economic, Environmental, and Management Problems Facing Massachusetts Commercial and Recreational Marine Fisheries. Massachusetts Division of Marine Fisheries, Boston, MA. MDMF Publ. H 14224-65-500-10-85-CR.
10 KOtiINSii\\ &ý PLDFt)5tN NIA I)'ll (MIL-SýaCIILu CIIS l)Clpartinlc t 01' Public I lcaithh. 1988. lealth Advisori lrot Contaminants t Fish and Shellflish kroi Quincy Bay. 20 June 1988.2 pp. Matthiesse G.C. (ed 1992. Perspective on shicllIshcrics in south-ern New E nolsand. T he SOunds Conservancy. Inc.. Essex C0. l'ubliciation #4 60 pp. Mc Bride. II.M. and I T I Hoopes. 2000. 1999 Massachusctts ILobster FishiCer SLIUSUCS.,lassacltLsetIs Division of Marine Fisherics. Boston. MA. MI)MIF Technical Report 'R-2..111v 2000. 22 pp. McDowell, J.E 1996. IIol ogical efltcts ofttoxic chemical contanii-nants in thil GulIof Maine. In: Iroccedins of the Gull'of Maine Ecosvtern D\\niiatics Scientific Synposium and Workshop. G.I. V, Iallacc and E.F. Ir aaschi eds. Regional Association tbr RcscarehI Ill the GuCIIf o. Mrine (RARGOM ) Report 97-1. p. 183-192. Murawski. S.A. R. Brown. H.-L.. Lai, 1P.1. Rago and L.. Hendrickson. 2000. Large-scale closed areas as a fishery-manageenent tool: The Georgcs Bank cxperienicc. Bull. Mar Sci. 66: 1-24. Murchelauo, R.A. and R.E. Wolke. 1985. Epizootic carcinoma in the winter flounder. Pseudopleuonectes rotericanis. Science 228: 587-589, Myers, R.A. NJ. Barrowman, I.A. Hutchings and A.A. Rosenberg. 1995. Population dynamics otfexploitcd stocks at low population levels. Science 269: 1106-1108. NEFMC (New England Fisher, Management Council). 1991. Northeast Multispecies FisheR, Management Plan. Amendment
- 4. 50 CFR Part 651. hIplemented 27 June 1991.
NEFMC (New England Fishler' Managemnent Council). 1994. Nortleast Multispc ics Fisher\\ N'lanagetinteit P'lan. Aniendcltelt
- 5. 50 CFR Part 651. hIplemented I March 1994.
NEFMC (New England Fishery Management Council). 1996. Northeast MIhit specics Fishery Management Plan. Amendment
- 7. 50 C:R Part 651. hIplemented I July 1996.
NEFMC (New England Fi Isery Management Council). 1999. Nolthcast MIhispecics IFishery Mlnaglienitt Plann. Amendment
- 11. 50 CFR liart 651. Implemented 21 April 1999.
NEFMC (New England Fishery Management Council). 2000. Framework Adiustment.33 to the Northeast Multispecies Fishery Management Plan. 3 February 2000. http :1/\\ wv\\. lie bitc.org/i idesx. hitit NEFSC (Northeast Fisheries Science Center). 2000. 30th Northeast Regional Stock Assessment Workshop (30th SAW). Stock Assessment Review Committee (SARC) Consensus Summary of Asscssltents. National Marine Fisheries Service, Northeast i sherics Scieince Centcir Rfclcrcnee Doatitletit 00-0)3. 477 pp. NMFS (National Marine Fisheries Service). 1999. Final Fishery Management Plan for Atlantic Tunta, Swordfish, and Sharks. lttp://\\vww.nm fs.gov/sfa/hms/iial FM11.1tinl. April 1999. NOAA (National Oceanographic and Atmospheric Administration). 1998. Status of the Flishery Resources o1ffthe Northeastern United States for 1998. NOAA Technical Memorandum NMFS-NE-115. National Marine Fisheries Service, Woods Hole MA. 149 PP. NOAA/NS&T (National Oceanographic and Atmospheric Administration/National Status & Trends Program). 2000. NOAA's National Status and Trends web page (July 2000). http://I%'www.orca.nios. noaa.,gov/proiccts/ttsandt/lttnl. NRC (National Research Council). 1998a. Improving Fish Stock Assessments. National Academy Press, Washington, D.C. 1998. 177 pp. NRC (National Research Council). 1998b. Review of Northeast Fishery Stock Assessments. National Academy Press, Washington D.C. 136 pp. NRC (National Research Council). 1999. Sistaining Marine Fisheries. National Academy Press, Washington, D.C. 1999. 164 pp. OGTF (Offshore Groundfish Task Force). 1990. New England Groundfish in Crisis - Again. Office of the Comin., Dept. Fisheries, Wildlife and Environ. Law Enforcement, Boston, MA. Orth, R.J. and K.A. Moore. 1983. Chesapeake Bay: An unprecedented declie mi sucbmerged aqualilc vegetatloit. Science 222: 51-53 Parsons-T. R. 1992. The removal of aarine predators by fisheries and the ilimpact oil trophic structure. Mar. Piollut. Bull. 25: 51-53 Pauly. D.. V. Christenseni.1). Dalsgaatrd. R. Froese and F. Torres. Jr. 1998. Fishing dowit 11arilc tbbod webs Science 279: 860-865. licderson,.1. and NM. Hall-Arber. 1999. Fish habitat: A focus on Nexw Fitgland tislicritan's perspectives. Amer. Fish Soc Svnpo. 22: 188-211. Pilgrim. W., L..Poissant and I.. Trip. 2000 The northeast states and eastern Canadian Provinces mercury study: A framiework for action: Summary of the Canadian chapter. Sci. -ot Environ 261: 177-184. Robinson, W.EF. IL.A. Carr and J. I arris. 1993. Assessment of ,uvenitc tBycatch and Codend S.urvivability in the Northeast Fishing IndUstry - Second Year's Study. Final report to NOAA/NMFS SaltonstalI-Kennedy Programn, December 1993 120 pp. Sarokit, D. and J. Schulkin. 1992. The role of pollution in large-scale population disturbances. Part I: Aquatic populations. Environ Sci. lTechnol. 26: 1476-1484. Serchuk. F.M.. M.D. Grosslein, R.G. Lough, D.G. Mountain and L. O'Brien. 1994. Fisher' and environmental 1mctors aftectmin trends aid IlucLuamiomS in the Georges Bank and Gullf of lainC Atlantic cod stocks: An overview ICES Mar. Sci. Syrun 198: 77-109. Short. F.T, A.C. Mathieson and J.L. Nelson. 1986. Recurrence ofthe celgrass wasting disease at tie border of New Hampshire and Maine. Mar Ecol. Prop. Ser. 29: 89-92. Siiderinann, C.J. 1994. Quantitative EIIcts of l'ollutioiti Oil NMaliie and Anadromnous Fish Populations. NOAA Technical Memorandum NMFS-F/NEC-i04. June 1994. 22 pp. Sissenwine, NI.P. and J.G. Shepherd. 1987 An alternative perspective on recruitment overfishitg and biological reference points. Carl. .1. Fish. AQuait Sci. 44: 913-918. Stevenson. I.K. 1904, Inlcorporation of htibitat intorinatioll in U.S. Fisheries Managemlient Plans:.Ali Atlantic coast perspective In: Gulf of Maine HabitaL: Workshop Proceedinas. RARGOM Report number 94-2. D. Stevenson and E. Braasch (eds.) Pp 51 - 63. Taylor, I,. 1998. Another approach to scallop production, habitat con-cerns, and biodiversity. In: Effects of Fishing Gear on the Sea Floor of New England. F.M. Dorsey and J. Pederson (eds.). Conservation Law Foundation. Boston, MA. Pp. 111-1 14. Weri-te, C.J. and R... Breteler i 983. Esiuarite Fisheries of tile North and M id-Atlantic: lHypotheses for Declintes. Prepared tor the National Oceanographic and Atmospheric Administration, Office of Pollution Assessment. 55 pp.
I : W IT iN G 1, R o i N i ! FI S I 1 1? 1 R ( F Chapter 11 The New EtguIad GroundLFish Resource: A History of Population Change in Relation to Harvesting STEVEN A. MURAWSKI A:ational.'IiL'[ariM Fisheuijs Servtice ANortheasi Fisheries Science Cenler H1`)ods Hole. il'! 02543 USA INTIWIDt ( ON The fishing industry of New England has, for over 4100 years, been identified both economically and culturally with groundtishing (German, 1987; 1-lennemuth and Rockwell, 1987). A mixture of bot-tom-dwelling fishes Including cod, haddock, redfish and flounders and allied bottoin-dwelling species (2onsti ttie thee rotnd fish resourwce (Table2-v Many of the groundfish resources off New England are now recovering from record low stock sizes and landings observed in the early 1990s (Clark, 1998). Management measures have only recently resulted in demonstrable reductions in groundfish mortality rates to levels low enoug1h to allow stock rehuilding (Northern Demersal Workineg Group. 2000). These recent reductions in fishing pressure required unprecedented regulation of a fishery that historically was allowed to operate virtually uncon-strained (Anthony, 1990, 1993; Fogarty and Murawski. 1998). Important historical themes in these fisheries were: (I) almost continuous change since the turn of the 20th century, owing to ecological, political and market trends, (2) gear sectors in competition for grounds, labor and fish,. (3) an eastward move-ment of the fleet to the Scotian Shelf and Newfoundland, followed by a westward contraction owing to changing markets and regulations, (4) "writing-off' of collapsed 'stocks, as effort expanded, and fisheries diversified, (5) failure to effectively deal with conservation problems in a timely fashion and to implement recommendations of scientific investigations, leading to (6) missed opportunities to establish sustainable fisheries or avoid major declines in production. This paper examines the exploitation history lor important groundfish resources off New England, and the role of fishing and other factors influencing stock abundance and recruitment. Research and mnanagement challenwyes in achieving stable and productive fisheries for these stocks are discussed. IIISIOIR ICAI., PI;;IRSIr(71nI f: DuVE'utCo'ŽrLYNT orF 0t-ru M1O1-11 FrSH-ERY In. the late 19th and early 20th centuries large fleets of vessels sailed from Gloucester, Boston and other New England ports to fish local and distant offshore banks as far away as the Grand Banks off Newfoundland and Labrador (German, 1987: Kurlansky, 1997; Murawski et al., 1997). Catches of salt cod supported nearly 400 schooners in each of these main ports, and a multitude of shore-side businesses including salt mining, ice harvesting in fresh-water ponds, and a boat building industry that made the shipyards on the Essex River, north of Boston, among the busiest and best known in the world. The fish landed in New England and the Maritimes eventually supported the infanmous "tri-angle trade' with Caribbean and west Afiican coun-tries and colonies (salt cod, molasses, and slaves; Kurlansky, 1997).
I 1 tll,,, S K ! lable 2.1. Species and stocks comprising the New England groundfish rCsoNrcc. Comnmon Name I " Scientific Name Manaemnent Included in Stocks F7 IM ulti-species F.N/P? Atlantic cod Gcorges Bank yes Alnico ad. r/aSou th GulfofMý.!,lInC yes Georges Bank ves H-laddock [ll cianotgrao'mno' lin G of Maine yes Gulf Okan e Acadian Redfish Sebatses fasciatus Gulf of Maine yes Pollock Pollachus virens Gulf of Maine yes White Hake LUrophysis lenuis Gulf of Maine yes Gulf of Nlaine/N. Georges Bank yes Red I lake Ut-oplihySg Chi.Ss S. Georges Bank/Middle Atlantic yes Silver I-lake Ak/1c~cius hiluinans Gulf of MaincN. Georgcs Bank yes S. Georges Bank/Middle Atlantic yes )Ocea) Pont A,\\.fr11'o-CE o 1:' & J cs Gulfofl'vlaine,'S. New Encland I s Atlantic Halibut Hippoglossus hippoglossus Gulf of Maine/Georges Bank Yes Geories Bank yes Winter Flounder P'hw rooectI's am'uric"'CinnS Gulf of Maine yes S. New England yes W\\ itch F lounder Gl7.nosossus Gulf of Maine yes i Georces Bank yes S. New En-land e 'Yelowtail Flounder [Li, /, S. Ne "nvanl es Cape Cod Yes Middle Atlantic yes American Plaice Hiippog/ossoides pi'aiessoides Gulf of Maine yes Windowpane SsGulf of &taineiN. Georgcs Bank yes Flounder S. Georges Bank/S. New, England yes Cusk 13rosme brosme Gulf of Maine no \\koIFlrish I4narchichoxvý loit..C Gulf of Maine no Spiny Dogfish Squahts acanihias NE USA and Canada 110io Skates seven species Gulf of Maine/Middle Atlantic no Gulf of Maine/N. Georges Bank no Goose fish Lophins anmericals' S. Georges Bank/Middle Atlantic no A. B. 41 ,,g* 1. ,a.. 4 5 - s.. B-4 Figure 2. 1. (A) Aieas closed to fshing in 1994 and the U.S./Canada boundary decided hy the Xorld Court (B) New England shore areas and fishing grounds. Year-round fishery closures for the protection of groundfish are'shaded.
\\1 % F " ( V. ,1 I \\ ",;, ( ý ý, x F 1D
- 1 ý R I: ý,,i ý rF The New E.'ngland roundfiSh i(LIstry\\ changed sien ilhcantlV around the turn of the century. Dur1 g *n this period, there were major shifts in how fish A
were cauLiht, hand led. processed, distributed and ,sold (Herrinuton. 1932.- Hennemnuth and RockwellI 1987: Scrchuk and Wig'ey. 1992). Once dominated. by artisanal, commI Lnity-based fishermen, the resource was subiected to increasing levels of. industrialization, first by company-based fleets of long-liners and gillnetters. At the turn of the century', steam-powered trawl vessels were specially-built to harvest flounders and haddock along the smooth bottomed areas along the continental shelf south and east of New England (Fig. 2.1 and 2.2; AnonynIOuIs 1906; Alexander et al., 1915). The introduction of the steam-powered trawler based oni desi gus from England (Anonymous, 1906) funda-Figure 2.2. Otter trawl fishing vessels at Boston Fish uPier, ca. 193 1. The vessel at the end of the pier is the mnl cSpray. Built in 1905 it was the first steam trawler rapidly replaced the schooner fleets. While it was introduced into the U.S. groundfish fleet. apparent that some stocks were depleted by the schooner fleetste..', halibut onl Gcorges Bank Stif-Year fered significant declines in productivity by the 1900 1920 1940 1960. 1980 2000 I 850). overfishing of various resources and other 60 - issties of fisheries management became more prob-50 Atlantic Cod leinatic with the introduction of trawlinr 40) (Alexander et al.. 1915.- Herrington, 1932).3 20it D (:vMi:*sTic O ve RFIS HnN G: 4o {. By 1930 there were clear signs that the fleet 180 had orown too large in relation to the capacity of 160 40 Haddock the stocks to sustain growth in landings 1 40 (Herrington, 1932). Haddock landings peaked in o 1929. but declined rapidly thereafter, as stocks -0 were less abundant on Georges Bank (Fig. 2.3). 60 This prompted the development of a modern stuidy 40 of the population dynamics of haddock, headed by 20 Dr. William Herrington (Herrington, 1932, 1947). 601 Yellowtal Flounde'r "It is oi/ly in the last ft/+ years when, the .f'shing leet has suffered oi'a marked scarcity of haddock that the/ Jolyf (heof 2(-e beliefin the inexhaustibiliot 0fnature has I0o become potent. " (-terrington, 1932). 0 ].. 1900 1920 1940 1960 1980 2000 Year A major focus of the program was to document Figure 2.3. Total landings of Georges Bank cod and had-harvesting practices and to determine appropriate dock and landings ofyellowtail founder from all New mitigation measures. The research by Herrington England waters, 1893-1999.
14 \\'R\\ .K (I1932) and Grarham (1952) confirmed the earl ier work of I'A xander et a1. (1915) demonstrating the large discard Of juvenile haddock, and great poten-tial wasie oftile resource. At this time catches of very small fish were common, with a large fraction of Iish beigL under 1 7 inches ill leng th (43 cm). It was readily apparent to researchers and some inem-bers of the industiry that the yield potential of fish was not being realized since they were being caught at a relatively young age, before achieving most of their growth potential (e.g. "growth over-fishing"). More troubling was the tremendous nur-bers of discarded baby" haddock, that were below commercially useful size (Herrington. 1932: (.iraham, 1952). Comments by one Clarence Birdseye confirmed industry leader's concerns for wasteful practices (see comments at the end of Herrington, 1932). Scientific investigations using sea sampling showed just how destructive the trawl technologv was. In 1930 the fishery landed 37 mil-lion haddock at Boston., \\with another 70-90 mrillion juvenile haddock discarded dead at sea (Herrington. 1932). The very small mesh size used in the nets was judged the catuse, arnd yet mesh size regulationis to protect haddock were not iimplement-ed until the U.S. had the authority to do so under the auspices of the International Commission for the Northwest Atlantic Fisheries (ICNAF), begin-ning in 1953 (Graham, 1952). Interestingly, a simi-lr sttudy published in 1915 (Alexander et al., 1915) also used sea sampling to document the high rates of hladdock discard by the otter trawl fisherv. Prior to WW-ll the fleet was large in size. but profitability was low (Dewar, 1983). The war years were again prosperous for the industry as produc-tion was boosted, and protein demands and rationinlg necessitated higher fish consumption. The fleet was reduced at this time, as many of the largest trawlers were requisitioned for war duty as mine sweepers. The return of these vessels from war, along with reduced demand resulted again in low profitability to the fleets (Dewar, 1983). Development of new markets such as selling ocean perch in the midwest as a substitute for Great Lakes yellow perch sustained the offshore fleet. Many government subsidy programs were launched after the war (Dewar, 1983). USA LANDINGS COD, HADDOCK and YELLOWTAIL CID WV '.nn;e 87 OWT 9 60' 63 66 56 72' 5-8 8 -8 687 '9 '.3 '.3-
- YEAR Figure 2.4. Total USA landings of Georges Bank cod.
haddock and yellowtail founder, 1960-1999. DISTANT-WATrER FLEETS Scoutinlg vessels for the Soviet fleets first ven-tured into New 1.n1gland waters in 196 l (I lennemtuth and Rockwell, 1987). Their target was Atlantic herring and their fishery took about 633,000 metric tons that.year. In subsequent years. the fish-ery for herring expanded, and other species includ-ing silver and red hake, and haddock were targeted (Brown et al., 1976; Mayo et al., 1992; Fogarty and Mu-rrawski, 1998). From 1960 to 1966 total ground-fish landings increased from about 200,000 metric tons, to about 760.000 metric tons. Landings of haddock reached an all-time record of 154,000 in 1965. arid declined rapidly thereafter (Fig. 2.3). Between 1964-1967 total groturidlrsh landings were comprised primarily of silver hake, haddock, red hake, flounders and cod. -lerring landings peaked in 1968 at 439,000 metric tons, and declined rapidly with the collapse of the Georges Bank herring stock (Anthony and Waring. 1980). The intensive mackerel fishery occurred in the early 1970s, with landings peaking in 1972 at 387,000 metric tons (Anderson and Paciorkowski, 1980). Effort exerted by tlhe distant-water fleets thus shifted frliom one abundant target stock to the next, in a typical pattern of sequential resource depletion (I-lennemuth and Rockwell, 1987). Restrictive man-agement actions, enacted beginning in the early 1970s severely limited catches, and distant water fleet effort declined accordingly (Hlennenmuth and Rockwell, 1987; Mayo et al., 1992). Total standard-ized fishing effort had increased four-fold on
E ý%, 17 N f; I D C
- 1) jfS I 1 0 1ý K t 11 S Hiure 2.5. NOAA RiV Albatross IV, launched in U.
and responsible for most standardized bottom trawl survey cruises betwecn 1963 and 2000. Georges Bank between 1960 and 1972 (May'o et al.. 1992). Under these high eflbrt levels, fishing mortality rates increased to unprecedented levels, and landings and stock sizes declined (Fig. 2.4). The Bureau of Commercial Fisheries instituted an innovative program to gain fishery independent data on fish abundance off the Northeast USA (Grosslein, 1969, Smith, 2000) beginning in 1962 Although standardized research vessel surveys had beguLn il the late 194i0s. iioust Ii~hery resecarch conducted on the northeast shelf consisted of sin-gle-species studies of fisheries involving data pri-marily derived from commercial fishing operations (Smith. 2000). Commercial fisheries data have obvious biases due to the concentration of fisheries in known areas of high density, and io-commer-cial components of the ecosystem could not be cthtwi n kz o from@:3 NMF boto traw S"333yS) 196= =:: 3 -99 R: EL: AT:i: i*:*=:*IV:::::i,. :: A,:NAN 0 'NOR:THWES JATLAN:.*
- I Ci I S GftOOS-I 6.3-,
- jj5;,
5 0 5 5i 5..... Figue 2.. Reativ abndane offourfinfsh pece grous fom fshew~idepeidet suvey (sratiiedmea cath/tw i kgfi'm NFS otom raw suvey), 96399 eflictively monitored using data solely from fish-cries. A new program was developed usinIg, statisti-callv rig!orous stratified random sampling designs. Beginning wvith the delivery of the NOAA Albatross IV (Fig. 2.5).in 1962, the Northeast Fisheries Science Center initiated Mihat has become the. longest con-tinLiously operating survey of its scope in the wvorld (Grosslein. 1969: Azarovitz el al.. 1997). The sur-vey has proved to be an invaluable tool to monitor specific stocks and species assemblages independ-ent of biases and data quality considerations inher-ent in fishery-dependent dala (Brown et al., 1976: Clark, 1981; Clark and Brown, 1977). Abundance, as measured by the Northeast F~isheries Science Center research vessel surveys, declined rapidly as various components of the demnersal and pelagic systems were pulse-fished by the distant-water fleets (Fig. 2.6; Brown et al., 1976: Clark, 1981). The Georges Bank haddock resource collapsed under the pressure from distant water fisheries, failing to produce any thing but .poor year classes between 1964 and 1974 (Northern Demersal Working Group 2000). Other stock collapses in.cluded silver and red hakes, Atlantic mackerel arid the Georges Bank herring stock (Fogarty and Murawski, 1998). Beginning in 1973, quota-based management was instituted under the auspices of the International Commission for the Northw est Atlantic Fisheries (ICNAF; Hennemuth and. Rockwell., 1987; Fig. 2.4). Quotas for each species were allocated by country, with the sum of each species equal to the total recommended removals. Additionally, 'second-tier' quotas, less than the sttm of a country's species allocations, were intend-ed to mitigate the effects of non-targeted bycatch, so that species quotas would not be exceeded. The quota system under ICNAF effectively ended directed distant-water fisheries on New England grotundfish resources, as these resources were determined to have little capacity to support fish-eries beyond the levels that would be taken by the United States and Canada. Quotas were progres-sively lowered on mackerel, herring, squids and other species, as these resources declined as well. 200-MILE LIMIT The clamor for the U.S. to assert control over waters out to 200 miles was great. The U.S. Congress
16 enacted the Mailuson lFisherv C(onsc'r\\ithor and Management Act of 1976, takim,- control o the exclusive economic zone (EiZ). and setting uP a system of reguIlation of the domestic industry. Fueled by great expectations, the U.S. fishing industry expanded i apidly i ordham, 1996). ' lhe fleet, once dominated by wooden side-trawlers, was repliaced virtually overnight by steel stern-trawlers which were equipped with modern tech-nology lor locating, catching and handling fish. Quota-based regulations, a hold-over friom the last days of international restrictions, were an anathema to the growth of the revitalized U.S. groundfish fleet. Catch quotas were abandoned, in favor of ineffective measures to control the size of meshes in the nets, and the minimum length of fish landed jlig 2,1 njljony, 1993). o one Akeimv exactly how -maniy new-coImiers iole a'ivc/ urehtr,' flhe /r'!i f.our monlhs Of 1977 biut accordhlig 0o one rFcnort. aeli boots entce/e w !he fishem; at 117f./oI/I? rote of oh'oulf onu everl, ,l ovs , (D .w:!/ 90,83). YEAR
- 9,C f975 0390 795
"'M0
- 995 2,00 Relatively strong year classes of cod, haddock and some other groundfish stocks produced in 1975 and later resulted in improved C resotirce conditions, and increased giomimdhi.h abundamice and effort in the late 1970s and early 1980s (Fig. 214, 216 and 2.7). Between 1976 and 1984 USA otter trawl fish-ing effori doubled (Mayo et al.. 1992: Anthony, 1993: Fogarty and Murawski. 1998), withl many new fishing vessels entering the fishe ry (Dewar, 1983). These newer vessels were more technologi-cally advanced, safer, and more capable of fishing in foul weather than the vessels they replaced. As a result, their fishing power was substaniially higher than those in the fleet prior to 1976.
Groundfish abundance again peaked in the early 1980s, primarily as a result of improving resource conditions for cod and haddock (Fig. 2.6 and 2.7). However, in the face of rapidly expand-ing fishing effort, abundance of the groundfish complex declined precipitouisly (Fig. 2.6 and 2.7). Il tile G(ul'Cf Maine. high relative catch rates were supported in the late 1970s and early 1980s by red-fish. haddock. cod (Serchuk et al., 1994) and mixed flounders. From 1970'onward the cod resource became the imainstav of the New England groundfish catch, as haddock and then yellowtail flounder resources collapsed (Fig 2.4). Tihe Canadians had extended their territorial jurisdiction 200 miles seaward. exclu~ding U.S. vessels which had fished off the Scotian Shelf and the southern Grand Banks for generations. With the return of the redfish fleet from the Scotian Shelf. as Canada extended its jurisdiction, the residual Gulf of Maine redfish resource was quickly depleted (Clark, 1998). Overlapping territorial claims in the Georges Bank region between the U.S. and Canada resulted in high-level diplomatic negotiations. In 1979 a draft treaty on reciprocal fishing rights was agreed to at the ministerial level. The treaty recognized histori-cal fisheries by the U.S. off Canada, and vice-versa. However, with the change in administrations in 1980, and opposition from some segments of the U.S. fishing industry, the draft treaty was not rati-fied by the U.S. government. Ultimately, the boundary between the U.S. and Canada was settled in the World Court (Fig. 2.1). Americans were barred from fishing areas off Canada, and areas in the northern part of Georges Bank, where so mudh of the haddock landings of the 1920s-1950s had been taken. 20] I-0 C 04 0 '2, 00 25 Georges Bank _R CodL SSB Georges Bank Haddock SSB ER Georges Bai~k Yellowail! S ER Georges Bank-. WinteKFt-ader 00 a-S 0.0 0.2 0.0 -09 -- 00 0,2 -00 - 08 .. 02 Lu 0 U] S!,1)0 1970 1975 1980 1985 1990 f995 2000 YEAR Figure 2.7. Changes in spawning stock biomass (SSB, 000s of metric tons) and exploitation rate (ER) for four New England groundfish stocks, 1973-1999.
f) F! I I R s;: lý ( !:'ý 17 On Gcor-es Bank, stock sizes of haddock, cod and yellowtail flounder, which had improved in the late 1970s-earl 1I 9 80s again declined as spawning biomasses and recruitment dinminished (Fig. 27). The strong 1987 y;ear class of Southern New England yellok tail lourider, was quickly lished out (Northern Demersal Working Group, 2000). As a result of the ~failure of indirect controls to prevent overfishing (NEFSC, 1987), environmental groups sued the Department of Commerce in 1991 (Fordham, 1996). The court settlement of the law suit required the New England Fishery Management Council to develop a fishery manage-ment plan to end overfishing and rebuild depleted stocks, the result of which was Amendment 45 to the Northeast Multispecies (groulldfish) I'MP, imp.lemented in 1994. This plan required a reduc-tion in groundfish effort by 50% over 5-7 years, increased mesh sizes, expanded closed areas, a mnoratorium on new effort in most fleet sectors, and iandatory reporting (logbooks.. Amendment #5 was implemented in May 1994. However. in June of that,ear. new fishery stock assessments indicated thatthe resource condition had deteriorated to the point that scientists warned: "Failure to lake strong manageleni aclions now ii ) /ves t e the limiled sp1awning hiomass finr Georges Bunk cod ,mav have severe and potentiallv long-lasting conisecquencesior both ihe stock andL.ishel);' -N-'C. 1994 In response, scientists reconmmnded "...substantial., immediate reductions in groundfish fishing mortali-ty on Georges Bank", and that "...fishing mortality for cod and yellowtail flounder be reduced to as low a level as possible, approaching zero" (NEFSC, 1994). In response to the poorer progno-sis for groundfish stocks, particularly on Georges Bank, the Secretary of Commerce instituted a series of measures under his emergency authority. Chief among the measures instituted was the clo-sure in December of about 17,000 kim-2 to ground-. fish fishing on Georges Bank and in southern New England (Fig. 2.1). The areas have remained closed to grourldfishing since then. Other measures, including the closure of additional areas in the Gulf of Maine (fig. 2.1), trip limits on some species and increases in mesh size were also instituted as part of later plan amendments. Rli:*( l>:t 1v: xN i Owiig to the decrease in lishimng e'lhrt (days fished), primarily by offshore trawlers, and the implementation of other measures including closed areas, exploitation rates for some stocks have decreased substantially in recent years (Fig. 2.7). In particular, exploitation rates of Georges Bank yel-lowtail fHounder, haddock, and to a lesser extent cod. declined to less than 10% per year, from lev-els, in the case of vellowtail flounder, of up to 80% (Fig. 2.7; Northern Demersal Working Group, 2000). The reduction in fishing mortality has had a significant impact on the age distribution of the stocks, especially for haddock and yellowtail floun-der, where older ages/larger sizes are 1ore abun-dant than in recent years when exploitation rates were excessive (Northern Deinersal Working Group? 2000). Increased sUortiVotship of older age grotups is thouight to be important in groundfish stocks. owimig to improved hatechingi rates and larval survival due to maternal spawning experience and size effects (Trippel et al., 1997: Murawski et al., 1999). In the case of some New England ground-fishes. spawning had become increasingly reliant on first-time spawners in years prior to 1995 (Wig le, 1999). Improved survival of older age groups is the primary reason for modest increases in spawning stock biomass (SSB) for Georges Bank cod (Northern Demersal Working Group, 2000); recruitment of the Georges Bank cod stock remains poor. In contrast, improved recruitment combined with higher adult survivorship has increased yel-lowtail flounder SSB to the highest level observed in the analytical stock assessment time series (e.., since 1973: Fig. 2.7). Haddock recruitment remains well below the historic (1931-1999) aver-age, but the 1998 year class is the largest since 1978. and is projected to continue expansion of SSB when recruited to the spawning poptilation (e.g., 2001). Although landings of Georges Bank groundfish stocks have remained stable since 1995, the species composition of landings reflects modest increase in
I8 B~a~o;s~zs G~ El COD HADDO~'( edd YELL QWTAffl I Figure 2.8. Spawning stock biomasses (thousands of metric tons) for Georg4es Bank cod., haddock and yellow-tail flounder. 1978-1999 (Northern Demersal Wbrking Group 2000j. diversity ainong cod, haddock and yellowtiil. flounder (Fig. 2.4). Spawning biomass increases among the species better reflect the increasing diversity (Northern Demersal Working Group, 2000: Fig. 2.8). as landings have been seriotisly con-strained. Aggregate spawning bioniass for the three Georges Bank stocks is now higher than any time since 1983, and will increase in the next few years (Northern Demersal Working Group, 2000). Other gronndlfish stocks (Table 2. 1 ), have showed variable trends in exploitation rate and stock biomass (Clark. 1998; Northern Demersal Working Group, 2000). In general, stocks on Georges Bank have lower exploitation rates and are further along in rebuilding to long-term bio-mass targets than are stocks in the Gulf of Maine region. In particula, Gulf of Maine cod and white hake resources, concentrated in the Gulf of Maine, have biomass <40% of the biomass that would pro-duce maxiiun tm sustainable yield (BMsy), and are exploited at rates above rebuilding targets. As traditional target stocks declined, the New England groundfish fishery re-targeted to exploit other available resources, including goosefish (rfionkfish), spiny dogfish, skates, white hake, northern shrimp and other stocks. Two important species to which effort was refocused were goose-fish (monkfish) and spiny dogfish. Landings of both species increased substantially in the early 1990s, reflecting increased directed fishing. In both cases. howcver. thie level of harvest resulted in non-sustainable harvest rates, and populations (par-ticularly of mature animals) declined (Clark. 1998: [Lao et al., 1999). F ishery mnanagement plans for both stocks were developed and are now imple-. inented to reduce fIshing mortality and rebuild tile stocks to BMSY, Tihe dramatic decline in ground fish abundance in the late 1980s was accompanied by a variety of changes in other fish components of the ecosystem (Fig. 2.6). In particular, there were rapid and sig-nificant increases in principal pelagics (Atlantic herring and Atlantic mackerel, as well as the sniall elasmobranchs (spiny dogfish and skates). The abundance of mackerel and herring declined to very low levels in the late 1970s. but has since rebounded to historic proportions (Clark, 1998). Iishing mortality of ierring and mackerel remains very low, as compared with sustainable harvest rates, and those observed when the distant-water Hleefs targeted them. Most of the increase in elas-mobranch abundance was due to the increase in dogfish, partictilarly since 1980 (Rago et al., 1999), The abundance of mat ure dogfish has declined sub-stantially in recent years, and the dearth of nature females in the population has produced very poor recruitment. Managers have severely curtailed directed fishing for dogfish in order to be able to eventually restore the biomass of mature dogfish to that necessary to produce MSY. Skate resources on the northeast shelf are coin-prised of seven species (NEFSC. 2000). The large-bodied species (winter, skate. barndoor skate and thorny skate) have showed significant signs of overfishing, due to their vulnerability to harvest and (in the case of winter and thorny skate) directed overfishing. Barndoor skate abundance declined significantly prior to 1970, and has only recently made a miodest increase in the past several years (NEFSC, 2000). Winter skate abundance on Georges Bank peaked in the mid-1980s and declined substantially thereafter. Thorny skate abundance has declined throutghout the past 30 years. The small-bodied skates (smooth. rosette. and little), have shown stable or increasing trends in recent years (NEFSC, 2000). As a group, groundfish resources have under-gone episodes of overfishing, in the usual scenario of discovery, build-up of directed harvest, overfish-ing and stock collapse. In several cases (haddock,
ilA ~ ~ P\\BI(if \\\\L CiK~ ý1ý.,11 Vs _ý () yellowtail flounder) there were a iulnber of such episodes durino the 19th and 20th centuries, while in others (redfish, Atlantic halibut. barndoor skate). the population dynamics of extreme K-selected species has precluded such c(clic response. For those stocks %%here fishing has been reduced to low levels hallowxing'a stoclk decline, in virtually all cases, a substantial recovery of' biomass and recruitment has ensued. Atlantic herring on Georges Bank were virtually etirpated in the mid-I-970s, but now appear to be at historic high levels. Likewise, mackerel recovered from overfishing to unprecedented high stock abundances. Numerous groundfish stocks including redfish, haddock, yel-lowtail flounder, witch flounder and others have increased substantially followiting relaxation of exploitation. There are a few exceptions. however. Red and silver hake populations in the Middle Atlantic Bight have'failed to recover following significant overexploitation by the distant water fleets (Clark. 1998). Gulf of Maime stocks of the same species have fared much better, deepening the mystery of the lack of recovery of these popu-lations. Several theories as to the kick of recovery of the two southern h1ke stocks include habitat destruction by demersal fishing gear. changes in the trophic composition of the system increasing predation pressure on juveniles, continued over-fishing of the stock (and in particular catch and bycatch Of juveniles) and changes in oceanographic conditions necessary for effective reproduction. These two stocks apart. the dominant factor con-trolling the population abundance of northeast groundfish stocks has been fishing. TIlE RoLEts OF OVERFISIIING ANI) ENIRONMENTIA L VAlIXTION Herrington (1 932) and Graham (1952) clearly demonstrated growth overfishing (excessive har-vest preventing maximum yield from a given num-ber of young fish over their life span) and incredi-ble waste of the Georges Bank haddock resource, owing to the very young age at selection and high discards by the fishery. Growth overfishing was a serious problem for most of the period before 1994, even with increases in minimum mesh size to 5-1/2 in. for the directed groundfish fishery, owing to the mis-match with minimum legal fish sizes (NEFSC, 1987). Only in the last several years YEAR CLASS 1970 IS975 1980 1985 1990
- 1995 2000 0
- 0.
GeogesBt cO m (0 01i 20 1" ýti- .oth 1970 1975 1980 1985 1990 3995 2000 YEAR CLASS Figure 2.9. Changes in recruitment survival (measures as recruits at age I per kg of spainine stock bioniasst for four New England groundfish stocks, 1973-1998. Horizontal lines are LOWESS smooths, assumini a tension value of 0.5. does it appear that the combinations of harvest rates (exploitation rates below -25%), and selec-tion characteristics of the gear extant in the fisheries result in near-optimum yield per recruit for some stocks (Northern Demersal Working Group. 2000). There is ample evidence for significant recruit-ment overfishing of many of New England's fishery resources throughout most of the 1 980s and early 1990s (Sinclair and Mtmrawski, 1997). Recruitment overfishing occurs when the reproductive capacity of the stock is decreased by fishing, so that the level of recruitment, on average, is substantially lower than when the spawning stock is larger-more mommies, more babies. Haddock are a good example of a stock substantially recruitment over-fished during various times during the 20th century (Overholtz et al., 1986; Overholtz et al., 1999). Although there is a great deal of variation in had-dock stock and recruitment data, it is nonetheless apparent that at stock sizes below about 80,000 metric tons, the probability that year classes >25
2 0 20 iiR.\\WS K I million fish will be produced is greatly diminished. By keeping the stock below the 80,000 metric ton level (e.g. since the late 1980s). the population has had insufficient reproductive capability (numbers of eggs spawned) to generate year classes in excess of125 million fish, except in years of unusually high survival of age I fish (e.g. 1975; Fig. 2.9). That the 1978 year class was good, and the product of the high spawning biomass of the 1975 year class (at age 3) and not unusually high survival rate (Fig. 2.9) is an important demonstration of the role of spawning biomass in determining year class strength. During the I 930s through early I 960s, the Georges Bank haddock produced year classes in excess of 25 million fish regularly, and very good year classes (>50 million fish) in about halfof the years (Overholtz et al., 1999). The 1998 year class appears to be in excess of 25 million fish, and, if conserved, should increase the SSB to over 80,000 metric tons in 2002 or 2003 (Northern Demersal ,Working Group, 2000). Analysis of the historical record indicates that recruitment prospects for Georges Bank haddock should continue to improve. Most northeast groundfish stocks exhibit sig-nificant, albeit noisy, stock-recruitment relation-ships (Brodziak et al., 2000). Given the substantial-ly greater likelihood of good recruitment at SSB's higher than the median, there is convincing evi-dence that maintaining high spawning stock will produce benefits in higher and more regular recruitment and yields to the fisheries. Natural environmental variation is a substantial contributing factor to the strength of individual groundfishl year classes, and, if not properly accounted for, can exacerbate recruitment declines due to overfishing (Werner et al.,_ 1999; Fogarty et al., 1996). The survival of young fish (expressed as a ratio of the number of age I produced per kilo-gram of SSB) exhibits important patterns of varia-tion, as illustrated by some New England ground-fish resources (Werner et al., 1999; Fig. 2.9). Recruitment survival was generally good for had-dock in the early 1960s, but declined in the late 1960s and early 1970s (Werner et al. 1999). This .pattern was generally similar for haddock on Georges. Bank and on Browns Bank off Southwest Nova Scotia, suggesting some level of geographic coherence, perhaps due to regional-scale environ-mental factors. Recruitment survival improved for Georges Bank Cod 220 200 180 160 Simulated, F=020 8o74 160 C 40 M. 20 ca Co 80 1977 7980 1983 1986 1989 1992 1995 7998 Year" Figure 2.10. Observed and simulated spawning stock biomass of Georges Bank cod. 1978-1997. Simulated SSB assumed that the stock was fished at F-0.2 (,16% exploitation rate) for years 1978-1997. Recruitment was assumOed to be that observed at age I. haddock in the late 1970s, but again declined in the 1 980s. Since 1990, recruitment survival has improved for numerous groundfish stocks (Fig. 2.9). The relationship between natural variation in recruitment survival and effects of fishing were evaluated in asimple simulation model (Fig. 2.10). Beginning i 1978 the calculated numbers of cod at age was subjected to various fishing mortality rate scenarios. Two simple assumptions of cod recruit-ment were used: (I) the annual numbers of recruits (age I) varied as observed in the fishery stock assessment (Northern Demersal Working Group. 2000), and (2) the observed pattern of recruitment survival (RiSSB), was mutltiplied by the simulated SSB to derive total recruitment. The importance of fishing to the overall level of SSB and the trend is given in Fig. 2.9. In this case, the only difference between the scenarios was the fishing mortality rate (Fig. 2.4 and 2.9). When the stock was fished at a low level (fishing mortality rate=F=0.2), the SSB peaked at over 200,000 mt in 1989, nearly three times the observed level. Although SSB declined from 1989 to 1997, the absolute level of SSB at the end of the simulation was over twice as high when F was low. The overall yield obtained in the low-F case was about equal to that assuming higher es, but was less variable from year to year. In the last few years of the simulation, the low-F scenario produced substantially higher landings. This simu-lation assumed annual recruitments as calculated
- I I ýV 1: N(i I k 1ý1 ý ( i.11, ý1 ý, 1) 1: 1 S If P 17,
ý: I i i,* ( 1: S ? I fi'oiu the. actual high-I. scenario. In all likelilhood, these hi-her simulated SSBs would have generated even hiherl recruitme nts. thereby producing still hi'her SSBs and landings. When the simulation was run with observed R/SSB values and simulated SSBs, the landings and stock sizes under the low-F scenario were substantia lyI greatei yet. This simple example shows the importance of maintaining proper exploitation rates during periods of both good and poor recruitmenl survival. When recruit-ment survival was good (early-mid 1980s), SSBs and likely absolute recruitment would have been much greater than that observed. In periods of poor recruitment survival, maintaining low Fs (or even reducing Fs when recruitment survival was poor) woulcd have resulted in smaller declines in SSB, and perhaps set the stage for a quicker turn around in SSB and yields once conditions for recruitment survival improved. Thus, rather than being an alter-native explanation for observed patterns of stock variation, natural lluctuations in the survivo'rship Of young fish may have exacerbated declines occur-ring due to overfishing. An important empirical observation (at least lor northeast groundtish) is that a conservative approach to exploitation rates. perhaps including' adaptive reductions in F when survivorship is poor, will produce greater long-term benefits and more stable catches than the opposite pattern of fishing mortality *ratcheting up' eventually leading to stock decline, typical of open access fisheries (Ludwig et al., 1993). The experi-ence in the northeast groundfish fisheries is a con-vincing case history o01 recruitment overfishing and the "ratchet effect"--a case that need not be repeated (Ludwig et al., 1993; Sinclair and Murawski, 1997). CONCLUSIMNS Groundfish resources in the offshore New England region have varied considerably in abun-dance and landings during the last 10 decades, pri-manly due to their exploitation history. Dramatic reductions in most offshore stocks occurred as a result of systemic recruitment overfishing by the distant water fleets, who sequentially depleted the wide array of species available. Subsequent to the end of distant-water fleet. fishing, some stocks rebounded to very high levels, only to be over-fished once again. The Atlantic herring stock on Gieores Bank was virtually extirpated in the 1970s, but has returned to relatively high abun-dance, and is now occupying historically important spawning areas. The Atlantic mackerel stock has, as well, increased in abundance following intensive overfishing in the early 1970s. Groundfish, however, did not fare well under domestic management following adoption of the Magnuson Fishery Conservation and Management Act (F'ordham. 1996). Most stocks oftgroundfish declined to near record low levels of abundance by the early 1990s, precipitating intervention in the management of the resources by the federal courts. Fishing practices during much of this period reduced the inherent resilience of the populations by removing many of the older (breeding) fish and resulting in the fisheries depending almost com-pletely on the strength of incoming year classes "recruitment fisheries"; Murawski et al., 1999). At lower exploitation rates, the population would be comprised of a greater diversity of age groups, and thus, if recruitment of the incoming cohort is low, the fishery could concentrate for a while on the accumulated stock of older animals. In the case of New England groundlish. however, high rates of exploitation obviated this option. The dependence on the recruitment of young fish resulted in great economic incentives to target animals at or near legal sizes. Retention and discard of juveniles became more problematic. Improvements in some resources followed implementation of direct effort controls (prescrib-ing a 50% reduction in days at sea), along with the first ever moratorium on new vessel entrants into the New England groundfish fishery, closure of. large blocks of productive fishing area, and other measures (Fogarty and M.urawski, 1998; Murawski et al.. 2000). The role of marine protected areas, such as the Georges Bank closures, in long-term conservation of resotrces and ecosystems is acL'r-rent subject of intense speculation and study. Closed areas on Georges Bank are important nurs-ery areas for a variety of grounldfish and other species (Muraxvski et al., 2000). Given the poten-tial for habitat destruction by heavy towed gears such as otter trawls and scallop dredges, it is possi-ble that improved recruitment may result from per-manent protection of nursery areas providing high quality feeding opportunities and cover from pre-dation. At this point, such mechanisms have not
11-. been Verified through scienltiic investigation, although some studies have been instituted (Collie et al.. 1997). Clearly. managers have found an ade-quate combination of measures that has allowed stock rebuilding to occur on Georges Bank (N'lurawski et al., 2000; Northern Demeisal Working Group. 2000). Some resources such as Georges Bank vello~wtail flounder are approaching target biomass levels, and could be harvested at increased rates. while others Will I requnire addition-al protection to achieve long term rebuilding (Applegate et al., 1998). The challenges for the next several years will be to manage the resource in a way that will allow less productive resources to meet their biomass and yield potentials while considering additional fishing opportunities for more productive stocks. Biomass goals have been established for all Of the significant resource species, but these targets have been calculated fr-om information collected from stocks that have been exploited at or above thein optiminurn rates for all of the recorded history. It is possible that yield poten-tials for some stocks max be much greater than the maxinlmu landings recorded in the fishery. owing to growth or recruitment overhishir-g. Thus, an adaptive approach to malaging recovering resources to assure that the lull productive poten-tialof the resources is realized is an appropriate goal for future research and management. In the future, consideration of the potential ecological constraints to the simultaneous optimization of bio-masses and yields of the array of resources species will become more important (IMurawski 2000), but there is considerable empirical evidence that at cur-rent levels of abundance, predation and competi-tion are not significant impediments to stock rebuilding for New England groundfish resources. The history of exploitation of New England's groundfish resource has produced a repeated record of failure to address identified conservation prob-lems followed by inevitable stock collapse and economic dislocation. The dominance of fishing as the primary factor indetermining the abundance of resource species, and in fact, the structure of the fish component of the New England offshore ecosystem has been established. Environmental variation, working to increase or decrease recruit-ment survival, has exacerbated the effects of over-fishing in some instances of stock collapse. I toxxever, it is tlhis variation that has allowed col-lapsed stocks to rebuild froml extremely low popu-lation sizes. For example, unusually high recrtuit-ment survival of haddock in 1975 and yellowtail flounder in 1987 (Fio. 2.9) resulted in significant but temporary stock rebuilding. as these year class-es were,,apidly Fished out. In the past. these urnusu-al events oh hih recruitmlent survival at loxw spawning stock sizes had been interpreted as evi-dence that environmental variation was the defin-ing factor in year class strength, and that spawning stocks could be fished to very low levels without threatening the productive capacity of species. More complete consideration of the relationships between SSB and recruitment, however., has estab-lished that for most grouildfish resources there is a higher probability of good recruitment at spawning biomasses above the median, and that good year classes are the product of good recruitment sur-vival combined with sufficient spawning stock. Thus, tile appropriateness of inanlaging for high and stable spawning stocks as a necessary element of fishery management goals for the New England ground fish resource is firCi1ly established (Brodziak et al.. 2000: Overholtz et al., 1987, 1999). 'he suite ofi anageinteu measures currentlxy in place has been sufficient to allow recovery of some components of the resource. The challenge for managers in the future is to extend rebuilding to other, less productive components of the resource. Given the complex biological and technical inter-actions among various resource species, extension of single-species concepts into an overall ecosys-tern perspective should allow consideration of the inevitable trade-offs between species. In the long run. conservative mainagement of fishing capacity for vessels capable of switching target species, combined with appropriate uses ot marine protect-ed areas to preserve ecosystem function and nurs-eries for resource species, and improved gear designs are undoubtedly the basic elemnents of a sustainable fishing strategy for the New England groundfish resource-a strategy that has yet to be fully realized. AC KNOWivu. DGNI ENTS This paper is dedicated to several individuals whose collective vision and determined hard work
forever chianoed the scientitic view of fisheries on the northeast shelf, and put into place data collec-tion schlemes and proerams of suifticient rigor that they have stood the test of time: William .-lerrinnton, William Royce, Herbert Grahain. Robert Edwards, Richard Hennem udh and Miarvin Grosslein. Generations of scientists to come will forever be in their debt. I also dedicate this review to the memory of Ellie Dorsey, a tireless worker for improved conservation of the region's fishery resources. LITfIRATUIREI CITED Alexander, A.B. II.F NMooir and W C Kindall 1 915 Otter-tra\\sl l'ishery. ApIpeniN VI. Repoit oe -'h !-nitcd Stats, Fishery Commission 1914. Washigton. 1) C Anderson. Fl.D3. and/\\ J Pacioilovsi, 1980 A rt.5 cv cx 'the north-west Atlnitic mackerel fishery. Rapp P.-v. Ruin. C0 ns. nLt. Explo. Mer. 177:175-2 11. Anonymous. 1906. The otter trawler Splay. Fishin" Ga7ette, 23(3l. Anthony, V.C. 1990, The New Englan'd gloUndtish fishery aftcr I0 S cars utnder tile *-ainlsicion s-s erv I xion a, 10 Management Act. N. Am. J. f-isherv Niana. IW 17' 5184. Anthony. V.C, 1993. The state oH groutindish resources of Ithe Northeastern Uniied States Fisheries 1 12-17. Anthony, V.C.. and (.T. Warini. 19801 ihe assessment and maniliagc-ieint of tile,t "es Hunk herr in, r'" 5'hrv. Rapp. P.-v. teun. C ons, ]o. I. xplo. M eIr-. 177 : - i11 Appl
- igate, A., S. Cudrl. J. I nitwIIIg C -N-tooIC. S. MI iaw i[id L.
Pikitch. 1998. Evaluation 01of existici" oVCrlisIhg defin'itjions and recommendations Cotr nietw overfishing definitions to comply with the Sustainable Fisheries Act. New England i isheries MantagemienCIt Council. Newtburyport_ MA. 79 pi. Azaroviiz. F., S. Chlak,., Despes and C Byrne. 1997 lihe Northeast Fisheries Science Center bottom trawl suIre'y programn. ICI-S CM. I 997/Y: 3 22 pp. Brodziak, I., \\V OvcIIIOloz, and 1'. tRago 2000. Does spawnhiln stock ai~e c -me-i'C\\eFlncn ') - ,_'¢1Id 111,11, Na Ial Namlc Fisheries Service, unpublished ma nuscript, Woods Hole Laboratory, Woods Hole, MA Brown, B.1.0., J.A. Brennan, I.1G. lleyerdahl MND. Grosslein and R.C. Ilenneiuth. 1976 Tlihe efiect of fishing oii the mar'ic fiish biomass of the Northwest, Atlantic fioim tle G(,ulf ofI Maine to Cape Hatteras. International Commission for the Northiest Atlantie Fisheries Research BullCtin 12 49-68. Clark, SH. 1981. Use of trawl suirey data Iii assessments. I'p. 82-92 In: W.G. Douibleday and 0. Risvird feds.] Bottom Trawl Suirveys. Canadian Special Publication oi tisheries and Aquatic Sciences 58. Clark, S. 1. (editor) 1998. Status ol i'shcrv resources off the Northeastern tUnited States tor 1998. NOAA Technical Mernoranduin NMFS-NE-115 149 pp Clark. SI-H. and O.E. Brown. 1977. Chanies in bioniass of fint'ish and squids from the Gulf of Maine to Cape Hatteras. 1963-1974. as. determined from research vessel survey data. Fish. Bull. 75:1-21. Collie, I.S., GA. Lscaneio, and P.C. Valentine. 1997. Lflects of bot-torn fishing on benthic megafauna of Georges Bank. Mar Ecol. Pro. Ser. 155: 159-172. Dewar, NI. 1983. Industry Ii trouble: The Federal governient and the New England fisheries. Tenple University Press,. Philadelphia. Fogarty, M. J. and S.A. Murawski. 1998. Large-scale disturbance and lhe SiUrcLliC Of l1r1W e S i'.sh.' -,-pa S Oil (r. OF CS Bank. Fcol Ap. 8, Supplement: Si-$i22 Ioiarti, NI.J.I R.K. MIaso, L O'(rien, F.INM. Serchuk, and A.A. Roscnbergr. 1996, Asssin' -,.cerai-itv and i isk -i exploited lIlariIC pOpulalions RcIia.U Svt Salv 4' 183-194,.
- Fordham, S.V, 1996ý New Engilaid rI undi 'i sh: Ft oio 'i to eriel.
Centeril r forh-c Cinseration, Waishci -c. D.F. 96 pp. German, A.W. I 9)8T Ilisiiy of, the early fishcries,c 1720- 1930. pages 409-4'l4 ii R Riackus jed.] Geoes fiank Massa-hus-us Institute ociihnobos Piess. Cabrinidge, MNassachusCtts. USA. Grahlail. I I.W. 1952. Mesh regu1h:tionls to Irrcs lde l ofd !ieh Georges Bank haddock fishiery pp. 23-33 In Intetrnational Commission t'Or Lile North,,Aest Atlantic Flshcr icý Annual.1 Rep~ort
- 2. IartmioilIth Nova Scotia Grosslein, M.D. 1969. Giiiitiidl'ish survey program ut BCF Woods ilole. NIti Ish. Rev. 31:22-30.
Hi-nctiiciiiuli. R.C, and S Rockwell. 1987. listori ofi fisheries ianil-agement and conservation. pages 4 30-446 in. R Backus led.], Geores Bank. Massachusetts lnistiittc ofl I-chnology Press, Cambridge. Mlassachusetts, USA Hccriincton. -W.C. 19132 CoIisci'iVla n." -i -ilL itc I 1_[i in otter irawlsr "Trans. Am. Fish. Soc 62: 7-63 I lcrrington, W.C( 1947. The 101C ei" intrisp-'ciic co'petition aid otheir Iactors in determining eilh population level oIa major marine species. Ecol. Monor. 1 T3 17-323 Kurlanskv, NM. 1997. Cod: A biography o: tile fish that changed the world. WAalker and Company, New Yoik 294 pp. I D, d Rii I I).i, . t lbllai nd Ci itO W'-
- 5. I t
i9 I -Ii*ie
- i',,'ý resur;Mce exploitation and Conservationi IessOIs I
- hOil, Iistor, Science
'60: 17, 36. Miaco. RK., M. It":.,gast, and -IM S'CetchK. 1992. A rc-ate fish 0io11ass and production on iciogcs Banik 1116-1 Q87 I. NW A1th1n. Fish. Sot. 14:5)-7'. Nitirawski. S.A., J.-. Maiure. R.K1. MIasi., and FNic SerlccIu. !997 UrIound'ish,stocks -nd the Iishing iidcsi, pp. 27-7-'D Ili:.I Boreman. t S. Nakaslhiiia.1. A. lso and R I Ki.endall (edi-tors) Northwecst Atlantic oocIndfish: Perspectives on a fisherx collapse. Amceiican Fisheries Society. Bethesda. 242 pp1 Iurasiski, S.A.X P.J. lago,a d I_ A. Iripp. i99-p a9ti of'demo-graphic variation 'Ii spawning success on rIcli.rence points for, f'ishery ninagemernt Pp. 77-85 In: V. Rstrepo 'iedl Proceedings of the Fifllh National NMFS Stock Assessment Wkocrkshop, Febrmars 24-2,1, 1998, Kes Iiargo-Floridia, NOAA Techlical M:cniioraiiidltfl NNIF S'-FI S --ft, PII ) Murawski, S.A., R. Biowsn, I.-L. Ia. PiJ. Rage and L. IHendrickson. 2000. Large-scale closed areas as a fishery-matnagemenit tool: The Georges Bank eiperience Bull. Mar. Sci. 66h1-24 Northeast Fisheries Science Center I NFlSC)1 1987 Status ui'fmixed species demcrsal finfish resources i New Enhilcd and scientific basis 'fLir manaigemeit. National Mai ine Fisleries Service, Woods Hiole Laborators' Rcleremce. Docuitent 87-08, Wo ods I ole, MA. Northeast Fisheries Science Center (NIIFSC). 1994. Report of the I 8th Northeast Regional Stock Assessment WNorkshop 1 18th SAW). Thie Plenary. National MNrine Fishieries Service, Northeast Fisheries Science Center Rel'crncl e Document r 4-23, Woods H-ole, NIA. Northeast Fisheries Science Center (NEFSC). 2000. 30th Noutheast Regional Stock Assesstlent \\Voikshop (30th SAW). Stock Assessment Revicei Committee (SARC) Consensus Summary Oif Assessments. National marine Fisheries Servicc Northeast Fisheries Science Center Reference Documen.it 00-03, 477 pp. Northern Demersal Working Group. 2000. Asscssitent oh' I I Northeast grouindfish stocks thrcoiugh 1999. Northeast Fisheries Science Center Reference Document 00-05. 175 pp. Woods -lole, MA. Overholtz, W.J., MNl. Sissenwine, and S.1. Clark. 1986. Recruitment variabilits and its implications for managing and rebuilding the
4 V! K I Gcor-ec, Mlink ihlddock i Ic! i .u;; a x1 AFis ii,\\ it xSc 52: 1044 - 1 Q57, Overhotz, WJ., S.A. NMirawski. P.J. Rago, .'1. Gabriel, M. lerceiro and JK.T. I3rodziak. 1999. ile n-ycar proieclinns of laodiiies. spanni no stock bioniass, and recruliteniti lbr i Ve New I-ngland groundi'ish stocks. National Marine Fisheries Service. Northeast Fisheries Sctince Center Reiferene Documeit 99-05 7-pp, Iaego. 1..I.- K A. Sosebxc, I.K.. Brodziak_ S.A. \\iirawxski and 1.D. Anderson 1Q08. Implications of recent increases in catches on tile dxilntmcs of Nortllwcst Atlantic spiny dogfish (Squaihis aOclin-dthilts Fishi Res I,,\\nistcrdim!, 30 ,6 1oI 1, Screhuk, F. ani d S.'. Wigley. 1992. Assessment and management ol the iicoiges Bank cod Oishry:an historical ix, vic d cLalin - tion. J1 NW Atdin. Fish Sci. 1325-52 Sercrlxtk, FNM., M.D. Grossl.in RG. Lough. and L. O'Bricn. 1994. Fishey and environmental factors affecgtii trends and fluctua-tions x Georgcs Bank aid G(ilf of Maine cod stocks: Ail overview. ICES Marine Science Svmposia 198:77-109. Sinclairi A. IF and S A. NIuraiski. 1()(9t7 Why have goroundfish stok declined? pp. i 1-93 I IJ. Boreman, B. S. Nakash ima,.1. A. Wilson and R. L. Keidl IcI i edior is Northwest Atlaintic groindfish: Perspectives on a fishery collapse. Amiericali hisherics Sociely, Bethesda. 242 pp Sni ith, TD. 2000 A talt otitWo grooiundfish trawl suirCys. CotxtribUted Paper ICES Siyixxpostinm "100 Years of Science in Under ICES", IHelsinkiI Finland, August 1-4. 2000 Trippel, F.A, O.S K esbu, and P. Solemdal. 1997. EIffects ol'adult ac ad t in zeC Sir itUrc oil rcproductiV Oe oIpott it ix1,1 ini C e 'ishxcs. pp. 31-62 In R.C. Chambers and E.A. Trippel [cds.] Early life hlistory axd recrUitmext li in fish populations. Chapman and Itlail, Next York. i W\\erner, F. N Miurawski, and K. Brander leds.. 1999. Report of the wiorks: t oii oeean cl ixisc of die NW Atlantic during lxte 1i960,s arndI iT7Os 'and consequences lrt gadoid poplati ons. ICES (3onipe ii.e Rlsctch cieport 234. C,,pei hagenx I lexiark. 8 I pp. Wialex S..
- 5.
1999 IfIccts oft first-time spaw/ners oix saick--rei uit-ment reiationships for two groundfish species. J. NW Atlant. Fish. Sei. 25215-218.
Chapmer 1.11 Recent Trends in Anadromouis Fishes .lOHiN M(ORIN\\i Unitel Slutes Geological illaine Coolperalive /iTsh Universi, of M'aine Orono. ME 04469 1.)A The beauy o/ this, Kennebec /is'he " / V1' s thacrt,/i'es'h/nlei" at Sold NaIIl'cc" r'fish Lept compair Thanks to the lir/es running up as far ets /obr miles, there were two uni-verses of fish at evervYfainlns foot. ihere i/see! to be legions q/1sbrilkedi bass. f-Capiain C&eorige7 /W'imouth saw great salmonn jcrnip/rrr out of the river Mhere Bath noi,slands. Am' there were slitr-geons longer than a mai. Sometimes they Camernight ubocad the canioes where meni were spearing them by torchlight, and upset the bout! -Roberi P. 7)'islarri Co//in. /937 tNTRODUCTION Anadromous fishes are born in freshwater, sub-sequently move into saltwater to grow, then return to freshwater to spawn. Because these fishes are dependent on diverse environments during different portions of their life cycle, they can be especially vulnerable to a variety of environmental changes. During their early life stages, these fishes are sensi-tive to deleterious alterations in freshwater. Later, when they pass through estuaries and into the marine environment, coastal pollution can affect survival. At maturity, habitat alterations, pollution, and commercial harvest can have profound impacts on spawning grounds. Therefore, not only are anadromous fishes subject to environmental and & Wildlfe Rescae/ch Unit harvest pressures at sea. they encounter dams, pol-Ilution, urbanization impacts, and habitat chanoes in freshwater. It is impossible to conclude how much anadro-mous fish habitat has been lost because we are uncertain of the origiinal historical distribution of these species. However, the construction of dams beginning in 1798 denied access for Atlantic salmon (So/mo salor), American shad (Alosa sapidissi/na), alewives (A. pseildoharengns), blue-back herring (A. aestivalis). Atlantic stungeon (Acipenser oxyrhynchus), and shortnose sturgeon (A. brevirostrumn), in particular, to most of their original habitat. Kimball and Stolte (1978) estimated that, by 1950, less than 2% of the original fireshwa-ter habitat was still accessible to Atlantic salmon in New England. With improvements inr fish passage and dam removal, that percentage has risento over 64% of the original habitat (USFWS and NMFS, 1995). The National Marine Fisheries Service (NMFS) has concluded that, "Atlantic anadromous stocks have been heavily influenced by nonfishing human activities in the coastal zone. Damming of rivers preventing occupation of former spawning grounds was a major factor in the decline of Atlantic salmon, sturgeons, river herrings, and shad. Environmental contamination is implicated in the declines of sev-eral species" (NMFS, 1992). As a consequence, successful restoration and rehabilitation of most species of anadromous fishes will rely on improv-ing the freshwater and estuarine environments through reduction of pollution, improvement of fish passage, and rehabilitation or protection of nursery and spawning habitats. Note: Author is deceased.
Y6 2 -I 6 N' (; Table 3. I.A a.ldro0Ious.Iish species ofI the Massachusetts Bay Recgion`, their relative ahubtdance, ntul Iers of streams. and aspects of freshwater residence-Further life history information can be found in Bigelow and Schroeder (1963). MNIurawski et aL. (1980), Danie et al. (1984). Mullen et al. (1986), Weiss-Glanz et al. (1986), and Jury et al. (1994). Species Relative abundlance Riiir inbr Ofi str~eamns Freshwater residence Atlatntic salmon !Striped bass iRaibow ssmelt Rare: extirpated: restora-tion on Merrimack River Upper portions of river; two years freshwater residence by juveniles ýSeasonally present in ,coastal waters and lower rivers in summer; Bay fish are from Hudson River and other areats ItSeasonallv common in spring: also landlocked populations in.lakes Enter Merrimack and Parker rivers from April to October; no spawning Sea-run brook trout fSea-ru n brown trout Alew keife B11lueback herring 'Rare, isolated populations Uncommon. few ]locati ons iVery common Colmlinon Enter coastal tributiaries in sprin4: eiLZs I m deposited in lower sections of streams: juve-niles abundant in estuaries AMove between lower sections of streams and Unknowrn Uestuaries Exotic fish introduced to a few streams and Unknown esftuaries: little information Merrimack and Charles rivers are principal II rtuns: enter frestwater to spawn in late spring ,where there is access to lakes: adults return to sea: juveniles in freshwater until October ?
- Similar to alewife, btut do not migrate far upstream Merrimack River is principal run: enter fresh-water to spawn in spring: use ipper portions of!
4,watershed where not blocked; young in fresh-
- water during summer
,A'erican shad iComtnon iShortnose sturgeon Rare Merrimack River: instream movements; spawn near some urban areas ilIven1iles enter Merrimack River in summer; [Atlantic sturgeon Uncolmmon I -adults and sub-adults in Bay': no river spawn-ing, although fish once spawned tip River [ .]200 km [.............. Exotic; previous introductions in New iPacific salnon species Rare Strays Hanipshire now largely gone; sonic remnant chinook salmon Sea lamprey Common -'Unknown Enter coastal streams for spawning, notably SN-lerrimack River 'The Massachusetts Bay Region is here broadly defined as the area from the mouth of the Merrimack River sotIth to Marshfield, Massachusetts (see USFWS, 1980). The minimum number of streams is the known nuImber of streams of any size.
N Ih' I >. "t.V hN,. 1 VI!lh 9 I It this Chapter. 1 wilt discuss ihe Status of anadromous ftsh species in the Mlassachusetts Bay and the larger Gulf of Maine region and identify: the causes of declines where known. These atte summarized in Tables 3. 1-3.2. After a historical cv revi , of ithe reg ion'S atit1fOl]tuu iisheries. I w 1il identify the principal constraints to and opportuni-ties for restoration and rehabilitation of these unique fish populations. Table 3.2. Summary of the status of anadromous fish stocks of the Niassachuseus Bay./North Shore region, in comparison to historical levels, and the principal factors affecting declines. Species Long-term trendf Short-term trend Factors involved Atlantic salmon Extirpated: iidergoing I ow returns Diams, pollution, overIrshing restoration Native population extir-b pated; declining numbers Increasing numbers of Habitat destruction, dais,pollution, over Striped bass of migratory fish from migratory fish fishing, now harvest reduction and non-Bay sources Variable, runs generally Stream blockage, siltation, possibly Rainbow simelt Declining high in 1989 and 1994, po1lution-decreased substrate quality, depressed other years predation by aquatic bids ISea-inn brook trout. Declining renknoat ipaos Urban development, habitat destruction remnant populations Increased stock in-and Sea-tin brown trout Introduced exotic species harvest
- Unknowi, Alewife Increasing after general Declines in 1993-1994 Habitat destruction dams, unknown decline factors Blueback hen'ing Increasing Declines in 1993-1994 Habitat destruction dams, unknown factors Declines in early 1990s; Ilabitat destruction dams, unknown slight rebound factors in 1995 Declining; Endangered R
Overfishing, dams, pollution: now harvest Shortno11se sturgeon Remnant populations Species List restrictions Atlantic sturgeon Unknown Stable or increasing Overfishing, dams, pollution; now harvest restrictions Introduced non-native Declining. stockin-now Pacific salmon species species, strays to terminated; adults will Unknown factors affecting survival at sea Massachusetts decline Sea lamprey Declining Unknown Dams aSince 1980
23 Tible 3.3. Status of U.S. AtUlitic salmon populations by river (Table firoin NFNIS. 1998). River System Population Status I lousatonic River Extirpated' u)innipiac River f Extirpated( t lammonassett River i Extirpated Connecticut River _ Extirpated Thalmes River Extirpated 'PawXcatuck River [Extirpated Pawuxet River Extirpated "ackstone River Extirpated NVierimack River Extirpated l amprev River Extirpated 'Cocheco River Extirpated ISainon Falls River j Extirpated NIConsatnt River Extirpated ,Kennebunk River Extirpated Saco River Extirpated ,Presumpscot River Extirpated RRoyal River Extirpated iindroscoggin Rivet - Extirpated iKennebec River Candidate Species Slicepseot River Unique Stock 2 IPerniaquidRiver Extirpated \\Medonak River Extirpated ýSt. Georges River Extirpated Duclktrap Rivet - Unique Stock [U , iT~ie --i* -i-(Te
- {*.....
ILittle River Extirpated Pass aassawaukeag River I Extirpated Penobscot River , Candidate Species i O*land River Extirpated Union River I Extirpaled ITunk Streamn Candidate Species Narragaugus River Unique Stock Pleasant River Unique Stock Indian River........ Extirpated
- Chandler River Extirpated C !] n s! e r
' *' e r..................................... !i?* *... Nachias Rivert Unique Stock East IMachias River Unique Stock 'Orange Extirpated Hobart Stream Extirpated Dennys River -______ -Unique Stock iP n '__ .k........... S ~............ TPennamaquan I Extirpated IBoyden Stream Extirpated IISt Cro ix Ri ver f Candidate Species Extirpated status could result from complete blockage of the river or a small population size. both of which indicate that long term persistence is unlikely. F igure 3. 1. Form er range o 'Atlantic sal on in the rivers of New England. Rivers in bold type probably had active salmon runs at the time the first European settlers arrived. Rivers highlighted with the widest line are cur-rently undergoing restoration. (Map troin International Atlantic SaImon Foundationi. 19791. Figure 3.2. The aboriginal distribution of Atlantic salmon in North America (map fiomn Watt, 1988). The solid black area represents habitat where the salmon have been extirpated by about 1870. The Atlantic salmon stocks in the rivers flowing into Lake Ontario and Lake Champlain were probably largely landlocked.
ŽI!yý' FT R;D N.\\'!\\.A! TiV 0?NM: ISFTTTS -)t Table 3.4. 1listoric and currently accessible Atlantic salmon habitat listed froom south to north. One habitat/production unit-100 in12. (Table from NtMIFS. 1998). New En gland Rivers Accessible I I lbitt IHistoric HabitatHabitat Unis Units i
- a. Laree Production Rivers (>10,006 production units)
(Connecticut River Mklerrimack River 89.2501 262.500: 83600ý Saco River1i 12,540 30 692 ................... )............................... \\ndroscM oin River 717 1,060i Kennebec River 1.0031 114,700. ' i c i~ {;
- 7 i-
- :, Te :....................................... ii 7 7........
I cnolm~ot River 1 017441 ~ 1 W680. Union River 8.3601 11,2021 o...Rivej .7............. 4
- b. Small Production Rivers (<I 0,000 production units)
Pawcatuck River 1671 8,7 78 Keepnetuk River I e -p s c -- t-R iv-e;7.... Duck trap Rive r Passagassawaukeag Rivet Narragaugus River 84 5851 1671 585i 1.672: 418. Jersey, but the major populations were ntntld it the Connecticut and Merrinmack watersheds of southern New England. and the Penobscot and Kennebec drainages of Maine. No one knows for sure how many salmon were present when the colonists first arrived, but the best guess based on available habi-tat is 100.000 adult salmon in New Ena la nd waters, including 30.000 in the Merrimack (Sto!te, 1981). The causes of the decline and extirpation of stocks have been well documented and talttibttied 1o dams arid pollution (Table 3.4). As the species declined; commercial fishing accelerated the extir-pation. The species was familiar to the first colonists (Stolte. 1981., 1994) and stocks have been exploited for three-and-a-hal l centuries. A 1ter a long period of fish absence., restoration progranis began in earnest in the I 960s, after the construc-tion of fish passage facilities and the enactment of several water quality laws. Restoration success in the Connecticut and Merrimack rivers has been only marginal, while that in Maine rivers has been somewhat better. Despite decades of stocking in the Merrimack River. restoration of Atlantic salmon cannot yet be considered successfiul (Table 3.5). A peak run of 332 adult salmon was achieved in 1991., but riuns only ranged from 23 to 248 in the previous decade. and dropped to just 61 fish in 1993 (Stolte, 1994), 21 in 1994, 34 in 1995, 76 in 1996, and 71 in 1997 (New England Salmon Association, 1995, 1996: United States Fish and Wildlife Service IIUSFWS] trap records). Returns in recent years.(1 23 in 1998 and 192 in 1999) are still disappointing. Despite the stocking of large numbers of fry (e.g., 3.1 mil-lion in 1994), the chances of full restoration seem quite distant. Less than 0.0007% of the fry that are stocked return as adults. The situation is only slightly better on the Connecticut River. Several hundred thousand smolts are stocked each year, along with several million fry (4 million in 1993, 6 million in 1994). Yet, the total returns for the past 10 years have been just over 2,500 salmon. That reflects an annu-al return rate of only 0.0004 to 0.4% from stocked smolts and 0.003 to 0.02% from stocked fry (Meyers, pers. comm.). Only 188 adult salmon returned in 1995, 260 in 1996, 199 in 1997, and 300 in 1998 despite the expenditure of more than $70 million on the program in the past three decades (Freeman, 1995; New England Salmon Pl easant River 5.7689 - 768! \\N'lachias River 269 502[ .Tunl, Stie-n 6,9399 69.939 ]g *, t *:ia i~i T i:* ~ e;................7 *....................
- i i~i.............:....................
-i Last Miachias Rie 2,174 2,174; 1Hobart Stream 841 84: Dennys River 2,090 2,090: iBoyden Stream 841 84' SPECIES S'IAI'US ATL.ANTIC SA.vMoN Alnost all runs of sea-run Atlantic salmon (Sanao salar) were eliminated in New England by the twentieth century, especially in southern New England (Table 3.3 and Figures 3.1-3.2). Salmon runs may once have extended as far south as New
30( Fable 3.5. Esrimated retunns of Atlaitic salmon to the Merrimack River, 1867-1999, based on trap counts. Data are taken from Stolte (1981 ) RideoLt and Stolte ( 1988), the New England Salmon Association (1996) and trap records of the U.S. Fish and Wildlife Service. Hi storical rI Estimated number of Cea r returning grilse, 2-se'l-year, and 3-sea-year fish n size 17,880( (range of 8,940 to 26,820) hSir. OltenI~)s atl re.s1toralioOl -7 166 54 [i 33(0 760 8...........8.. . 588 Yea r (continued) Estimated number of returning grilse, 2-sea-yearr, and 3-sea-year fish '1867-1875 1882 188 1884 9 9..1 1991 1199.2 199 I 99 1 61 11994 12 _199_5 34 1996 76 11997 71 i 1998 i12i 1999 192 .............. [.............. Recent returns ,1993 .61 1886 '1887 !1889 '1890 1,500 1.927 1,141 1,796 1994 1995 1996 2,1 34 7) 11891 1,653 189 2 3,062 i _ 9..................... I 8918 3.600 1894 929 1895 1.776 1896 1,034 11897
- 241, 1898 16
....... i..... Second alteil/)ts at IresloIlCuion 197581977 0 1979 33 1980 5 I1981 125 1982 23 1983 114 1984 115 il985 213 11986 103 11987 139 11988 65 11989 84 1990 248 Association. 1995). Returns of adult salmon to waters in Rhode Island and New Hampshire have been minimal. Farther to the north, there has been more success in restoring Atlantic salmon to the Penobscot River, Maine. Yet. despite a peak run of 4.125 in 1986, recent numbers of adults returning to the river have shown declines (1,578 in 1991, 1,650 in 1993, 1,342 in 1995, 2,052 in 1996, 1,342 in 1997 and 1.2 10. in 1998. Only 969 adult salmon returned to the Penobscot River in 1999., and the total run for all Maine rivers was only 1,164 (trap records, Maine Atlantic Salmon Authority). Similar declines have been evident on many rivers, including those in eastern Canada and the runs in wild riv'ers of Downeast Maine. Clearly, some unknown factors are affecting survival of salmon. The database for documenting returns of Atlantic salmon is good, but the causes of the low numbers of returning adults in recent years are not known. Many experts suspect factors in the marine enVironment are dictating return survival, possibly ocean wanning along southern portions of oceanic
1ý 1 IN I N 1) 1, 1,', 0 \\1 ý ý!,ýS F I ý I I I zý habitat or cven ocean cooling nnear Greenland (Friedland et al., 1993). But there are two other obvious factors that likely play a role in restoration success ill southern New England waters. First, even though upstream fish passage facilities exist at the lower dams of the Connecticut and Merrimack rivers, and downstreami passage is planned lfor the lower dams, mov ing up or down past any darn involves some level of mortality. e.Cen with itie most C licient passag Ge iciitis. Thus, despite fish passage improvements, survival of Atlantic sanirion iil New Fmwland streams contin-ues to be low compared to waters in eastern Canada, where there are generally fewer dams and higher fish populations. Second, the salmon brood stock used to initiate restoration was taken from the progeiiy of fish returning to thic Penobscot River, Maine, a source quite distant.from the Massachusetts locations where the native stocks were extirpated and the habitat altered. The Penobscot strain, in turn. is a hybrid, derived tiom a combination of non-extirpated fish returnirlito Downcast rivers of Maine and fish returning to Canadian rivers--becauws the nalive Pen1obscot strain was also extirpated. Thus, restoration efforts in southern New England relyf oii a hybridized fish whose relatives were adapted for life in waters much farther to the north; this is especially true for fish in the Connecticut River. Because salmon in Massachusetts are in the soLithern Mairgin Of the historictal range of the species. the task of restoration is especially diffi-cult. Add to this the recent trends in global warm-ing, and at least one scientist has predicted that "Global warming could ultimately make restora-tions on the southern edge of Atlantic salmon, the Merrimack and Connecticut, difficult or nearly impossible" (Bielak, 1994). How native Atlantic salmon of southern New England may have responded to even subtle warming trends is a moot point, as restoration nowv involves a hybridized, non-native stock. Return rates of salmon from the Connecticut and Merrimack rivers average only 12 and 27%, respectively, of those on the St. John River, New Brunswick, while those of Atlantic salmon from the Penobscot River, farther north, average 89% of the return percentages from the St. John River (USFWS and NMFS, 1995). ArIi7RiCAN SHxD Commercial landings olfAmerican shad (Alosa .supij;.s.sima) peaked in 1970( when about 3.000 mt wei'e taken in northwestern Atlantic waters. But recent harvests have only been one-third of that level (NMFS. 1992). Statistics specific to New England are unreliable through the 18th and 19th centuries: however, landing records for the entire Atlanfic coast suggest that 1896 wvas a peak year with catch figures about six times what the\\y were in 1960. Historically, runs declined dICe to poil-tion and inadequate fish passage, but some of these declines likely were masked by the natural cyclical nature of year classes. Except for the most recent rui years. there have been modest success storieCs in southern New England, such as runs.on the Connecticut River, but most populations in other rivers have been depressed, especially during l 993-1994. Most runs in Maine. for example. were eliminated due to impassable dams and pollution and are only now shimwing some successes in restoration in a few riveis, primarily due to stocked. transplanted fish. Those shad that survive spawning, along with immature adults, generally migrate to the Bay of Fundy, and remnain there during the summer and into the fall (Melvin et al.. 1992). During winter months, shad from New England move into an area between Long Island and the mid-Atlantic coast. Thus. shad are influenced not only by conditions in freshwater but by conditions in several areas of the G l-of Maine aiid soutLIw ard aswell. Runs of American shad have generally increased in, Massachusetts waters in the 1990s, a rehabilitation success story that has not been com-pletely smooth. After gradually increasing until 1993. runs on the Merrimack River declined by about half each year in 1993 and 1994 before increasing again in 1995. Recent returns have been impressive (22.586 in 1997, 27,891 in 1998, and 56,465 in 1998), the highest three annual runs since records have been kept (USFWS trap records). Apparently, the 1993-4 decline was due to some unknown factor at sea, as similar declines were experienced in the Connecticut River stock, where shad runs decreased to record lows in 1994 and 1995 (B. Kynard, U.S. Geological Survey, Turners Falls, MA., pers. comm.). Only 300,000 shad returned to the Connecticut in 1995, less than
12 9% of the run of 1992, although returns in 1996-1998 have exceeded 600,000. AI.EWIVES AND BI[.UFACK I ERRING Adult alewives (Alosa pseudohareigus) and blueback herring- (-i1osa aesthal/;S) (ksomlenilmes grouped together as "'river herring") usually return to saltwater after spawning, and may spawn more than once. Individual stocks havr been reduced due to pollution and danis that altered habitat and blocked access to spawning sites (Jury et al., 1994). The National Marine Fisheries Service (1992) considers alewife and blueback herring (river herrings) stocks as variable, dependent on local conditions. Commercial catches for these river herring peaked in the 1960s along the north-eastern coast, when 27,000 mt were harvested annually. In recent years, the harvest has only aver-aged 1.200 mt (NMFS, 1992). River herring runs on the Merrimack River had been steadily increasing, until 1992, but have declined ever since. The 1999 run of 7,898 was only 2% of the size of the run in 1991, but has been an improvement over the historic low return of just 51 fish in 1966 (USFWS trap records). The recent years of poor returns have not been linked to any specific cause. There does not appear to be any in-river change that could account for this decline. Without a specific freshwater factor, all indicators point to some unknown factor at sea that is increas-ing mortality of northern Massachusetts stocks. Similar declines have been noted for runs in the Connecticut River, where spawning numbers of 410,000 blueback herring in 1991 declined to 12,000 in just seven years, despite a Juvenile Alosid Index prepared by the State of Connecticut that predicted record runs. The actual returns were half and one-quarter of the predicted runs over the two years, respectively (B. Kynard, pers. comm.). RAINBOW SMELT Although never experiencing the widespread extirpation of runs as have other anadromous species, the distribution of sea-run rainbow smelt (Osmerus mordax) in coastal rivers has been affect-ed by natural and human-made obstructions, silta-tion, decline of substrate quality, poor water quality, and other unknown factors as well (Buckley. 1989). No sinlee cause has been implicated. Rather, declines in individual streams are due to site-specific combinations of the above factors. Runs of rainbow smelt are extremely variable, but the long-term trend indicates a decline of coastal pop.tlatio ls in southern New England. In the past 15 years, only runs in 1989 and 1994 were considered good. In all other years since the early I 980s, numbers of returning adults have been extlrelely low. particularly' in the years 1990-1993 (B. Chase, Massachusetts Division of VMarine Fisheries. Salem, Massachusetts, pers. comm.). The cause of the declines is unknown but increased pre-dation by aquatic birds, and spawning substrate degradation are strongly suspected. Populations of several species of coastal birds have increased dra-matically in recent years (Krohn et al., 1995), and the deterioration of small coastal tributaries has been shown to reduce spawning potential (S. Chapman, Darling Marine Center, Walpole, Maine, pers. coinnm.). Surprisingly, runs have shown improvem1ents in some urban rivers, tributaries to Massachusetts Bay, While runs are decli ning in less urbanized rivers with better water quality. The issue is unresolved, but may involve other undlocu-mented factors as well, such as the success of Chesapeake Bay and Hudson River.striped bass rehabilitation, which has led to the recent large increases in striped bass from those areas feeding in inshore waters and river mouths, particularly the Charles and Weymouth Fore rivers. Additional monitoring will be required to identify specific causes of declines, as they likely are a combination of factors. Similar declines in interior waters of Massachusetts have been linked to acid precipita-tion and a resultant decrease in pH1 (B. Kynard, pers. comm.). and this may be a factor in anadro-mnous runs of rainbow smelt as well. where low pH levels also have been recorded in coastal tributaries (Haines, 1987). Rainbow smelt do not utilize fish ladders and even modest amounts of woody debris in streams will block upstream passage. Thus, urban development and related land use activities in the lower portions of coastal streams can result in increased instream debris and can effectively block upstream access. There also has been a noticeable decline in substr ate quality in many coastal streams. Smelt
PFý'Eýl I ViNDý IN A\\A7D;:?0V0T ýý 1:1ýýHF cggs are adhesive and naturally stick to instream rocks, aquatic vegetation. and submerged branches. I However. in recent years, there have been notice-able declines in aquatic vegetation and increases in algal growth on instream cover (B. Chase, MNassachusetts Division of Marine Fisheries, Salem. Massachusetts, pers. comm.). Eggs do not adhere to unstable substrate, such as.algae, and some reproductive potential may be lost. The wide-spread growIt of algae may be linke'd to changes in water quality and \\,,ater temperature. Even a modest increase in angler etlbrt in coastal rivers can affect rainbow smelt populations. Murawski and Cole (1978) used predictive models to show that populations could be severely impact-ed by increased angler harvest in some NMlassachusetts rivers. MI assachusCtts has had a modest enhancement program in the past where eggs were collected and transported to waters with depressed smelt populations. However. the tech-nique has been temporarily suspended because of the lack of documented success of such practices. A Massachusetts Bay smelt monitoring program introduced eg." into an unaltered stream in 1995 to assess the suitability of egg transfers (B. Chase, . pers. cornin.). Enihancement of stocks, throtigh transportation or other means, has high public appeal, but transfers have had only mixed success in New England, partly because the extreme vari-ability of year-class strength can mask the success of rehabilitation techniques. ATLANTIC AND SHORTNOSE STURGEON The shortnose sturgeon (Acipenser brevirostrtun) is on the Federal Endangered Species List and con-siderable research is Underway in Massachusetts on spawning behavior and movements, and in Pennsylvania on fish culture. The species is rela-tively abundant in coastal waters of northern New England and preliminary estimates have been derived for the populations in the Kennebec River, Maine (T. Squiers, Maine Department of Marine Resources., Hallowell, Maine., pers. comm.). Atlantic sturgeon (Acipenser ox -'rhv nchus) are rare in northern New England (only seven were netted in the Kennebec River in 1994). but more abundant in southern New England. Both species, however, have been affected by a combination of urban development, destruction of spawning grounds, obstruction of hish passage, and over-exploitation. Atlantic sturgeon were once harvested in the Merrimack River in the nineteenth century, but reproducing populations no longer exist. Atlantic sturgeon are considered quite abun-dant in the Massachusetts Bay area, arriving friom Maine waters or the Fludson Rivetr (or offshore waters in Massachusetts Bay) in May, and remain-ing around the many islands of the Bay through the summer (B. Kynard, pers. conm.). Juvenile Atlantic sturgeon enter the lower Merrimack River in summer, then ieave to go oflshore in the !ill, possibly joining aduilt Atlantic sturgeon in Massachusetts Bay. The North Shore and northern Massachusetts Bay coasts are apparently used as heavy forage areas for Atlantic sturgeon. Although population estimates are unavailable. biologists currently do not consider the species threatened in the southern Gulf of Maine, as they are in the northern Gulf region (Kieffer and Kynard, 1996; B. Kynard. pers. comm.). Shortnose sturgeon are much less abundant in the North Shore/sotithern Gulf of Maine region than in the northern Gull' of Maine. A-reninant pop-ulation of less than 100 shortnose sturgeon exists in the Merrimack River, movi ng up and dows n the river (B. Kynard, pers. comm.). A few fish are encountered in the Connecticut River. One area of concern is that prelerred spawning areas in the Merrimack River are primarily in heavily urban-ized sections of the river, Sticih as the concrete-lined sections in downtown I laverhill (Kieffer and Kynard, 1996). As a consequence, the areas needing particular protection are often the areas most sus-ceptible to impacts by hmmans. STRIPLD BASS I mnysel/at the turn of the tdcle have seene such multitudes pass out o/a [pounde that it seemed to me that one inughte go over their backs drishod. -Captain John Sm ith, 1622 Harvested since the arrival of the first colonists to New England, the striped bass (Alorone saxatilis) was largely extirpated from most rivers
,4 f! i ( of: New Fngiland. due directly to habitat destruction, pollution, dams, and overfishing. Each has played a inajor role in the extirpation of native stocks, but dams and overfishing were probably most respon-sible Cole, 1978; V'loring, 1986; Squiers 1988).I Such declines were not limited to New England, but have been present throuighout the range of' striped bass. By the early 1980s. larval fish counts in Chesapeake Bay and elsewhere were the lowest on record. Howeveer tihe success of' several nleas-ures in the 1990s has led to a remarkable recovery of lludson River and Chesapeake Bay' stocks. Unlike the restoration techniques employed for Atlantic salmon and American shad, providing fish passage is not the answer. Striped bass will not use fish ladders, so river systems with dams, however efficient the fish passage facilities, effectively block upstream distribution off striped bass. Thus, as long as dams remain in place on lower portions of New England rivers, full restoration of striped bass to historical spawning grounds will never be achieved. On a positive note, the removal of the Edwards Dam on the Kennebec River at Augusta, Maine in 1999 provided striped bass and other anadromous fishes access to the river upstream to Waterville for the first tine since the 1830s. uill restoration of the species to the lower portions of rivers also depends on remediating any water pol-lution problems, which is a process that effectively began in the 1960s. IndiviCduals migrating in coastal waters from Connecticut northward to Maine in summer are often derived froom populations in the Hudson River and Chesapeake Bay (Flagg and Squiers, 199 1). Although some striped bass tagged in Canadian waters have been recaptured in New England (Rulifson and Dadswell, 1995), striped bass generally move northward from the Hudson River and Chesapeake Bay in summer, as water temperatures increase. The-travel singularly or in groups, feeding on inshore fishes and sea worms, and entering the lower portions of rivers in the Massachusetts Bay region. Thus, recent increased numbers of adult and immature striped bass in Bay w aters is a reflection of restoration success else-where, not in Massachusetts, as native populations here have been extirpated. Populations alone the east coast declined rap-idly in the 1980s, but restrictions on sport and commercial catches, habitat improvement, and reduced pollution have recently led to i Mirked increase in population numbers. Larval counts and numbers of adults have shown remarkable improvement in the last two years in Maryland waters, and increased nummibers o01 migrating adults have been subjectively rioted in Mlasschusetts coastal regions and river mouths as well (B. Kynard, pers. comm.). It is difficult to conclude which rehabilitation technique has been responsible for the recent success aInd the subsequent increased numimber of' fish entering waters of coastal Massachusetts, as all techniques were initiated simultaneously. However, it is likely that Federal pressutre to reduce harvest by 50% had significant in 1 tuence. There are more striped bass today in the lower Merrimack and Connecticuit rivers and along the North Shore of Massachusetts than were present even a few years ago (former National Biological Service. National Marine Fisheries Service, unpub. records). Since there has been no direct evidence of natural reproductiori in Massachusetts waters for decades, the striped bass present along the Massachusetts Bay coastline in summer must origi-nate elsewhere. Tagging studies indicate that Hudson River striped bass are the ones most likely captured by sport anglers in New England, although some scientists suspect that Chesapeake Bay stripers visit the area as well. Most New England states have some level of restoration program lor striped bass. Maine has been stocking juveniles into the Kennebec River, obtained fromn hatcheries in New York, for the past decade. Until recently, striped bass captured along the Maine coast in summer were the product of fish born elsewhere, as is the case with Massachusetts. However, there has been evidence of natural reproduction every year since 1987 in the Kennebec River and, most recently, in the Sheepscot River (L. Flagg, Maine Department of Marine Resources, Hallowell, Maine., pers. comm.). Thus, some larger striped bass encoun-tered in the summer from Cape Cod to Maine may be the offspring of fish naturally produced in Maine. There has been no direct evidence of natural reproduction in Massachusetts waters for decades. Re-establishing actual spawning runs in Massachusetts waters will require stocking of spring yearling fish.
iCFECI ZEN IIF, IN AN,\\RWN!011iS lFISHES 3,5 S\\A-RUjN BROOK TR(OIUT AND SEA-RUN BROWN TROUT Localized populations of wild sea-run brook trOutl (N.o/l .. !sin Yfionul l di,<,) are lotilld iII coastal streamis ot Newv Ingland and ast-ern Canada. Such populations are isolated in New England and more commoni---even abundant-northward into rivers of eastern Canada in areas where stream pH is not low. Some intrirmation is available on Gulf of Maine populations and at least two states (Massachusetts. Maine) have considered modest management programs. In all likelihood, sea-run brook trout populations are more common than long assumed. Runs inl eastern Maine (Ritzi, 1953). and southernH MIaine (M. Dionne, Wells National Estuarine Research Reserve, pers. comimn/.) have survived largel]\\ because of inininmal urban development and poilu-tion and limited angling pressure. The surviving native populations are in isolated, little-developed coastal streams. Because of the popularity of this. anadromous form in eastern Canada, fisheries man-agers in Maine consider coastal runs to be candi-dates fbr new and expanded fisheries (R. Owen, former Commissioner, Maine Department of Inland Fisheries and Wildlife Augusta, Maine, pers. comm.). Thus, increased exploitation of these wild runs is probable in the future-Remnant runs on Cape Cod have co-existed with humnain populations since colonization by the first. Europeans. Management strategies in Massachusetts today include slocking ol alternativ'e species, such ais brown trout, Sahino trulia, to lessen fishing pres-sure on these unique wild stocks (Bergin, 1985). The brown trout is a species introduced from Europe, and both the true sea-run form and the non sea-run form have been introduced into lower rivers and estuaries of New England states. Several significant coastal sport fisheries have developed, particularly in major rivers where pollution has been reduced. Although brown trout are exotic fishes, they have been established in waters of North America for over 100 years and represent an increasing resource opportunity. There is almost no information on sea-run brown trout after their release into coastal rivers except that they experi-ence rapid growth in summer months ill coastal estuaries. P\\(i FIC S\\I.C N All five species of Pacific salmon (Oncotivnchius spp.) have been stocked in New IEng'land waters, but ire not nativ.e here and natural spa\\Vnin has enIeirally not been doc ui ncmited. Three species also have been reared in coastal aquaculture operations in the past twventy years (pink salmon, 0. gOrbits-hoa; chum salmon, 0. keto: and coho salmon. 0) kis tach). In recent years. New Hampshire has had a significant programn of stocking coho and chinook salmon (0. tschawv./scha) to create coastal sportfisheries, but stocking of coho salmon was terminated in favor of chinook salmon. Stocking of the latter species was terminated in December 1993 because of lo\\V ieturns and encouraging, early returns from stocked Atlantic salmon. Pacific salmon are non-native species and the potential for competition with native freshwater and anadromous fishes has never been fully explored. However, numbers introduced into New England waters have decreased dramatically. Chinook salmon stocked in 1993 will continue to be encountered in southern Gulf of Maine waters for several years. then will disappear if natural reproduction does not occur. Ocean ranching oper-ations in southern Maine in the early 1980s for pink salmon and chum salmon were largely unsuc-cessful, apparently due to inadequate water temper-atures. Expansion of the species and associated fisheries into Massachusetts seems unlikely, partic-ulyar with the current cemphasis on restoration of' Atlantic salnon. SEA LAN4MPPrm The sea lamprey (Jelrono, marints) has been commercially important in the past. The fish was used by Native Americans for centuries and was taken commercially in large numbers from the Merrimack and Connecticut rivers in colonial times. Runs declined rapidly due to the construction of dams, especially on the Merrimack River (Bigelow and Schroeder, 1963). Currently, runs are stable, although lower than in historical times, yet harvest and consumption are almost non-existent. For unexplained reasons, the trap count of sea lam-preys tripled on the Connecticut River in 1998, the
36 highest nutmIbers on record, but numbers iIn Other years have remained steady. There are. however. efforts underway to develop a market for lamprey skins to be marketed in Asia for the creation of purses, wallets, and other products. n uch in the fashion of wolffish skin and shark skin. -lISTRinc:t. ]"RFrNDS IN NEW E>NGlAND Sahloio shad and alewives were.briner/v abundant here (the Merrimack River), and taken in weirs by ithe Indians, who tagzht this method to the whites, 15. whom thev were used as food and mCHInrP, urntil the dam and a/fter`IVOa the CC a00! al i ,i/ k4caL, c(i1/d i//.i( 1 cltoiets Lowell, put Cn end to their migrations hitherward. though it is thought that a few more enlep)rising shad may, still be seen; -Henmy David Thorecbo, 1849 Althoug-h there is some question as to tile ma-nitude of runs of anadromous fishes before the Little Ice Age (ca. 1450-1800 A.D.), particularly with Atlantic salmon (Carlson, 1988), Native Americans surely utilized several species of anadromous fishes. Atlantic salmon were plentifnul at the time of the first European settlements in New England. although no one can accuratelv assess the sizes of runs. Stolte (1986) estimated 300,000 adult Atlantic salmon, based on habitat availability. Tie construction of a dam 160 kml upstream fiom the mouth of the Connecticut River in 1798 marked the beginning of a decades-long extirpation process of anadromous fish runs in New England. Locks and canals on the Merrimack River started to appear at the end of the eighteenth century and the construction of a dam near Bristol, New Hampshire, blocked the upstreamn passage of fishes in 1820 (Stolte, 198 I). Whatever the specific local situation, American shad, Atlantic salmon. ale'wives, blueback herring, striped bass, and rain-boxw smelt were all declining in southern New England by 1870 (Bowen, 1970; Moring, 1986). The causes were primarily the impassable dams located at numerous locations along the ConnectIicuti, Merrimack, and other in ijor rivers of New England, and the heavy pollution near towns and mills. The first dlain on the ( onnccticuL River Was constructed in 1798 at Turiiers Falls, M,'lassachusetts. It was 16 teet high and impassable to inigrating fish. Others soon followedl on the Connecticut, Merri1mack, Kennebec, Penobscot, and other rivers ol New England. Probably the first species to receive supple-mental stockimg to reverse the declining runs was the Anemrican.shad. Over 200 million eggs were artiticially [latched in northeastern states during a five-year period, 1866-1871 (Bowen, 1970). By 1866, runs of Atlantic salmon were severely depleted in southern New England and eggs were brought from the Miramichi River, New Brunswick, and implanted in gravel in the Merrimack River. Several states were actively putr-chasino Atlantic salmon egos in the late I 860s to booster declining stocks of salmon. The first salmon hatchery in the United States was at Craig Brook, near Orland, Maine: it distrib-uted tip to six million fry in the early I 870s to states as faar south as New Jersey (Bowen, 1970). These efforts continued until the twentieth century, when the once abundant runs of Atlantic salmon in Maine began to suffer a similar fate to those in Massachusetts, Connecticut, and Rhode Island. Eventually, there werle iew brood stock available to supply eggs or fry. By the early decades of the twentieth century, runs of Atlantic salmon were extirpated fi'om all the rivers of New England, except for several smaller streams in Downeast and central Maine (Moring et al., 1995). In concert with the declines of Atlantic salmon, rainbow smelt were similarly declining due to blocked passage, pollution. and habitat destruction in lower rivers. As early as 1874, regulations were enacted to limit commercial catches (Murawski and Cole, 1978). Striped bass were eliminated from many rivers of New England as early as the I 830s, due to dams and pollution, while runs of Amnerican shad, blueback herring, and sea-run alewives declined due to fish passage problems (many runs in northern Maine were even extirpated). UnreCulated commercial harvest of Atlantic stur-geon in the late nineteenth century led to depletions and extirpations of populations that were fished until they were no longer economically profitable.
PI-I-ENF !RENDýý IN %NADPO%1011ý HS[IFS 37 ,Most restoration and rehabilitation efforts in tile Gulf of Maine reoion have occurred since 1960. The major focus has been on tile construc-tion of fish passage facilities and the inmprovement o' water quality in rivers. Once the issues of dams and water pollution were addressed in individual rivers, stocking and harvest regulation could pro-ceed with somne posibi lity of manattCwement success. MIany\\ New England rivers still have dains and pollution issues that aft'ect fish populations, so the process ol rehabilitalion Of fish runs is ol necessity ail ongoing process. Although population levels of all anadromous species are well below historical numlbers, American shad and blueback herritng pro-granms have shown the most success in tile Massachusetts Bay/southern Gulf of Maine region. CURRENT AN) FuIURI C(.NSTRAINTS OBST'RUCTIONS ANi) FisiI PASSAGE-i By their very nature. anad rontoIs fishes in ust descend rivers, later ascend rivers and, in some cases, repeat the process more than once. Downstream passage mortality associated with damis varies with fish passage design, but has reached 62-82% for American shad and blueback herring on the Connecticut River (Taylor and Kynard, 1985) and with similar values on other northeastern waters (DuBois and Gloss. 1993). More recent studies have estimated mtuch lower mortalities, due to higher recapture rates and lower mortalities in control groups (Mathur et al., 1994). Mortality rates for passing Atlantic salmon have ranged from 9-23% in waters of Massachusetts, New Hampshire, and Maine (Stier and Kynard, 1986; Moring. 1993). Stream blockage is likely one of the causes of the decline of rainbow.smelt in the past decade and has certainly led to declines in striped bass. As these two species do not utilize fish ladders, re-establishing historical levels of these fishes will require removal of some dams (such as recently occurred on the Kennebec River) or refinement of fish lift technology. W:Vi'ER Qt.,\\ sitl Freshwater tributaries of teie Massachusetts Bayi/'North Shore area continue to be sources of pollitants (13ro tin. 1987), L t1 h 1[1 water \\; uality is less ora constraint for re-establishinlg historical levels of anadromous Ifishes than was the case decades ago. Since the passage of a number of tederal and state laws in the i960s and 7i/s that promoted water Cluality improvenients, many rivers of New England have shown substantial improve-ment froml tile heavily polluted condition of earlier times. Nevertheless, in 1995. more than half of the lower Charles River, between Newton and Waltham. was covered wvith aquatic vegetation-- primarily water chestnut. Such dense vegetation caii affect wvater quality and even block fish pas-sage. The principal cause was the heavy nutrient load to the river from human sources, such as lawn fertilizers, septic tank input, and raw sewage (Allen, 1995). Sonic of this material eventually reaches Massachusetts Bay and influences water quality as anadromous fishes enter coastal streams. Levels of PCB and Mercury continue to be accu-mulated by fish, necessitating fish consumption health advisories for humans (see Chapter 4 by Thurberg and Gould). There is no evidence that contaminants arc today adversely affecting the health of adult anadromous fish in New England. However, there have been recent studies with freshwaterand estuaritie fishes that indicate fish subjected to higher levels of mercury in the envi-ronrent may exlhibit behavioral changes or reduced reproductive success (Wiener and Spry, 1995; T. Haines, U.S. Geological Survey, Orono, Maine, pers. comm.). Specifically, avoidance of predators may be impaired and hatching success reduced. This has been untested for anadromous species of North Aierica, but such subtle impacts could result in lower survival of fish in streams with higher mercury content. It is likely that some water quality factors continue to influence spawn-ing runs and spawning success of rainbow smell and may affect other species as well, such as PCB problems affecting striped bass in the Hudson River.
LA..ND)tJ PRALic:'1`.S Several types of land use activities can disturb aquatic ecosystems and potentially cal have a sig-nificanil impact on a.adromous fish duriing their freshwater residence. Moring et al. ( 1994) sumInIa-rized the physico-chemical and biological changes that can occur when forest canopies are opened,. riparian vegetation is removed, stream banks are altered, or roads are constructed. These conse-quences include increased sedimentation., excess particulates in gravel. increased stream flow. increased temperature, decreased dissolved oxygen, decreased insect drift, decreased fish populations, losses of nutrients flrom watersheds, and ecological shifts in enerCy input and fish and macroinverte-brate species diversity.. Such disturbances occur fr-om agricultural use. road construction, loggiug, and urban development, and can directly affect nursery and spawning habi-tat of anadromous fishes. An extensive review of the biological consequences of such land use prac-tices indicates few definitive studies in New Lugland (Moring and Finlayson. 1996), except Cor the Hubbard Brook studies in New Hampshire (e.g. Likens et al., 1970) and several logging sttudies in northern Maine (Moring et al., 1994). There have been no studies in New EnLoland that directly link such land disturbance activities to losses of anadro-mous fishes. However, urbanization along coastal tributaries and logging in upper watershed tributar-ies of the Merrimack River likely influence differ-cut stages of anadronious lishes. EXPLOITATION Overexploitation, primarily by commercial fishers, has contributed to the decline in striped bass, Atlantic salmon, and Atlantic sturgeon. Maryland is the major spawning area for striped bass that migrate along much of the northeast coast and the state where the bulk of the commercial catch has been centered. In the 1960s and 1970s. the total catch of stripers by commercial and recre-ational fishers in Maryland was roughly the same, thus both probably contributed to the collapse that ensued. Once the stock collapsed, however the sport fishery dropped to less than 20% of the com-mercial catch while the commercial fishery contin-tied their harvest until drastic management measures were imposed. In New Fngland, commercial fish-ing for stripers has traditionally comprised a small-er percentage of the catch than that of recreational anglers so its impact has probably been less. For Atlantic salmnon, Maine has long had a recreational fishery which was finilly hanned in 2000. Now that the dcays of river trapping (19th and early 2' 0th centuries) is over, the maiJor harvest of these fish is by coinmercial fishers on the high seas beyond US territorial waters. For stiurgeor. there is currently little take these days. but previ-Otis sport and commercial tIshers were responsible for limited harvests. More effective fisheries management plans will minimize the effect of harvest on anadromouIs species. particularly niumbers of spawners. Two recent management actions show how this can ben-efit these fishes. Federally-mandated increases in the minimum size limit for striped bass have appar-entlv achieved the desired effect of reducing har-vest by 50%. Maine (the only state that always had some level of sportfishery for Atlantic salmon, until 1994. with catch-and-release from 1995-1999) reduced the sportfishing-induced mortality from 20% of the run to zero. iwo other management actions just adopted will hopefully have positive effects on anadromous fish populations. Recent negotiations wvith Canada and the buy-out (at least temporarily) of the WVest Greenland fishery for Atlantic salhon may prove fruitful in the next sev-eral years if higher numbers of adults stirvive ocean fisheries and return to Massachusetts waters to spawn. A new fisheries management plan for shad and river herring has just been adopted by the Atlantic States Marine Fisheries Commission in response to declining runs of those species. In addition to fisheries management plans, the exploitation of some anadromous species is restricted under other environmental regulations. The shortnose sturgeon is protected under the Federal Endangered Species Act. The Atlantic sturgeon may be listed soon. COASTAL AQIJACUI.,TURE In recent years, Atlantic salmon, rainbow-steel-head hybrids (Oneorhynchzis in vkiiss), and Arctic char (Salhelinus alpinus) have been reared in off-shore cages to meet market demands for salmon
11F E )1 iN1S TN '. im~NN[ s 39E aInd trout. At present, most such activity is CiLIS-tered around the Maine-New Brunswick border, although aquacLIture operations have been estab-lished from Cape Cod northward at various times in the past. Tihe mna jor biological concern is that escapees fr-om these cages are now entering U.S. rivers. A storm in fall 1994 resulted in the escape of' thoutsands of Atlantic sallmon, nianiv of" which were subsequently encouniered in coastal rivers of eastern Maine. Generally\\ 10% of caged salmon are likely to disappear from cages durinu rearing (Moriing,- 1989). If thly originate lioon non-native sources, these escapees can and do hybridize with native stocks, thus altering the genetic components of salm1on used in restoration. Even though the stock ofAtlantic salmon that is used in restoration of the Merrimack River is non-native, selection is faCvoring an artificial "'site-specific" stock that does return and reproduce. Thus. genetic dilution of such fish could further reduce the possibility of restoration. Another threat is represented by the recent outbreaks of two diseases in both cultured and wild stocks of Atlantic salmon of eastern Maine and New Brunswick. The cultured stocks may be acting as reservoirs of diseases that get passed on to the wild stocks" SYNERIST I( CoNS [ S)F RAH ONS Increasing population numbers of anadromons fishes is a difficult management premise because no single species can be managed in a vaCULuim. For example, as striped bass numbers increase, more of these predators will, be entering the lower portions of New England rivers. The success of their feed-ing in these habitats will depend, among other things. on the success of programs to increase runs of Atlantic salmon and American shad. Survival of Atlantic salmon smolts, rainbow smelt, and alewives, in turn will be influenced by the breeding success of federally-protected aquatic birds, such as double-crested cormorants (Phalacrocorax aw-i-liuts), the popularity of new sea-run brown trout spoil-fisheries (potential predators of smolts and prey for striped bass), and the success of striped bass restoration programs, as well as fishing and non-fishing human activities. Thus, rehabilitation pro-grams must be managed fr'om a broader perspective. The interaction of anadromous fishes and other forlls ofx wi Idlife are most obvious with respect to aquatic birds. Federal protection of -double-crested cormorants and other species since 1916 have recently led to exponential increases in coastal Ib)reeding populations in Massachusetts (Krohn el al., 1995). The number of breeding pairs o" (double-crested cormorants in Massachusetts has more than tripled in less than 15 years, from 1.760 to 7000. and the number of bird colonies has almost dou-bled durin( that time (Krohn et al.. 1995). These birds are known predators of such anadromous species as rainbow snielt and Atlantic salmon smolts. As the bird popuIlationIs have increased, pressure on anadrom0ous stocks also increased. A recent estimate concluded that over seven percent of the Atlantic salmon smolts in the Penobscot River ate consumed by cormorants in the spring as the Fish inigrate downstream (B3lackwell. 1996). It is difficult to reach conclusions on a New England-regional basis as cormorant predation varies locally. dependent upon the presence of dams and breeding populations. AlthoucLh cormoranlts have been the birds most studied as salmon predators, at least six other bird species are known predators on Atlantic salmon smOlts in New England and eastern Canada (Moringi et al.. 1998). As cormorant populations have increased (or in some cases stabilized), other birds, such as terns, have concUrrently declined. Thus, the overall impact of bird predation on salmon and other fish species still needs to be assessed.I Links between Massachusetts anadroinous fishes and inshore and offshore marine fishes are less clear. Successftil restoration of Atlantic salmon, for example, may have been hampered in the early 1980s by substantially increased harvests of capelin (Mallotus villosus) on the high seas. This osmerid is the favorite food of Atlantic salnion in offshore waters. SUIMMARY OF ISSUES FACING ANADROMOuS FISllES Anadromous fishes,. by their very nature, are influenced by conditions in freshwater as well as at sea. Stocks of all anadromous fishes in the Massachusetts Bay region have declined from his-torical levels, principally due to dams, habitat alter-ations and pollution. To a lesser extent, overfishing
40 \\1l i~ ý . (ý on declining stocks also has played a role. Initially, impassable dams blocked upstream passage of anldrinomous fishes. thus preventing fishes from reaching most spawning grounds. The first types of' Fish ladders and lifts were quite ine-ticient, but state-of-the-art designs of today still involve somre mortality in passage. Downstream fish passa h has lagge-cd behind concerns flor upstream passage, yet this Is equally important. Mortal it o" dojtream-n (grathtie uvenile and adult fishes can be significant due to mortality froom turbines and predation, but recent advances with bypass systems, especially with Atlantic salmon, have shown promising results. Water level changes dux to competing demands for surface waters also iayx be an important factor. but this tieeds ore stUdy. x A signirilcant portion of the habitat once utilized by anadromous fishes is no longer available. Thus, the reproductive and nursery carrying capacity of New England freshwaters is no longer as high as. it was in Colonial times due to blocked passage and land disturbance activities, such as agriculture and lo gginge. Since the mid I S00s, pollutants have continued to influence the freshwater life cycles of anadro-moIts fishes Impaired Water qiuality together with blocked fish passage was a major cause of declines and cxti tPtn or antdroIIos stocks. Mil l and tannery wastes, sewxage effluents, heaxv metals (particularly from industrial plants and paper com-panies). and sawdust and pulp from sawmills and lumber companies have all entered rivers tributary to the Gulf of Maine. The most severe pollution occurs in coastal waters, obviously because these areas are adjacent to the land-based and discharge sources of pollu-tants. Anadromous fishes can be severely impacted by heavy metals, pesticides, hydrocarbons, and effluents because they pass between the coastal waters (as well as polluted rivers) in their migra-tions between freshwater and saltwater. In addition, as Thurberg and Gould summarized in Chapter 4, many pollutants have more pronounced effects on immature stages of fishes. The majority of species of anadromous fishes in New England do not travel far from shore; larvae and juveniles in the inshore, more heavily-polluted waters are faced with the consequences of pollution. Although pollution is significantly lower in the twenty-first century, levels of hiavy tetals, PCBs, and acid precipita-tion still may be adversely alftecting anadrotnous fishes, especially through levels in sediments. When a fish stock is dlecliini, commercial or sport exploitation only axccelerates the decline of anadrotnous fishes. It is an additive factor that can sometimes become critical in the presence of other contributors to stress and moittalitv. AnLe'I s have taken a portion of returning stocks, yet this source has never been considered a primary factor in the overall declines of stocks. Commercial fisheries (First in freshwater, then in saltamer) have played a role in the decline of striped bass, Atlantic salmon, and Atlantic sturgeon. With current management efforts reducing the commercial 'and sport catches of striped bass and Atlantic salnon, harvest activities will likely have less negative influence on restoring anadromous stocks. There are restoration or rehabilitation programs utnderxwav for almost.all anadromous species in the Massachusetts Bay region, 'some modest and some quite extensive. The results have varied (Tables 3.1-3.3). Runs of American shad have shown the most iinprovement, although progress with river herring seems a distant prospect. Numbers of striped bass along the coast have increased recent-ly. but not as a result of natural spawvning in Massachusetts. Coastal runs of rainbow smelt appear to be declininigt over a broad -eocraphi cal .area; returns in 1994 were high. but thistmay be an anomaly. Native runs of sea-run brook trout appear to be stable. Atlantic salmon restoration has shown -little success despite decades of heavy stocking of fr'y and smolts. Drought conditions in 1995 do not appear to have adversely affected juvenile Atlantic salmon in streams (R. Spencer, Maine Atlantic Salmon Commission, Bangor, Maine, pers. comm.), but witnter survival may have been reduced as a consequence. Restoration or improvement of anadromous fish populations in the region seems to be a func-tion of many factors, each of.which must be improved in order to.show tangible results, particu-larly: improved fish passage, increased availability of appropriate habitat, improved water quality, and well managed sport and commercial harvest. The priority for restoration and rehabilitation of anadro-mous fish runs in the Massachusetts Bay region and other areas of northeastern United States should be to provide suitable habitat for species
i Z1 11N L>I Dii Iv -i.\\ c iN & A 1 z(I%1t1,SIcyct S I f I I and access to that habitat. If that is accomplished, the imnpediments to restoration will argely be those of natural variability in ocean conditions. REsi*\\IwCII NcEIws Despite the Iong history of exploitation of anadronmo's fishes. and the lecgthy, dcaiabase, several areas of research are necessary lor future manage-ment, restoration, and rehabilitation. RLunS of alewives. blueback herrin-., and Atlantic salmon are being minluenced by. some undocumented marine factors. In order to properly evaluate man-agement and regulatory actions performed on behalf of these anadr"oinous stocks, it is necessary to know why runs have declined despite improve-ments in water quality and fish passage. I his requLiirCs rcserch oIi occan warining and cooli] a g trends, commercial harvesting, and the dependency of these anadromous species on certain prey items, such as capelin. Another area of concern is restoration of striped bass stocks to southern New England and elsewhere. The modest, but consistent. su ccess of Maine's restoration program tprovides some evidence that important gains can be achieved with moderate Financial investment. Factors influencing distribuh-tion and spawning success of striped bass need to be investigated. Third, the Fragile existence of sea-run brook trout stocks from Cape Cod northward in the United States needs to be identified and man-aged. Our knowledge of the biology. seasonal movements, and habitat requirements of this anadromous form is primarily firom waters of the Maritimes. Fourth, broader-scope investigations need to be initiated that involve multi-species approaches. For example, striped bass restoration in waters contain-inc, sea-run brown trout or sea-run brook trout should be conducted after studies conclude that predator-prey influences are not self defeating. The success of one program should not be at the expense of another program, just because the two are conducted by separate agencies working in the same geographic area. ACKNOWLEIDGMIf:NTS I wish to thank Duncan Mclnnis, New Ilam pshire Fish and Game Department; Brad Chase and Randy Fairbanks. Massachusetts Division of Marine Fisheries; Richard Hartley, Massachusetts Division of Fish and Wildlife: Larry Solte,.oe IcKeon, and led lMevers, U.S. Fish and Wildlife Service; Norm Dube and Randy Spencer, Maine Atlantic Salmon Commission: Lew Flagg and Tom SqUiers, Maine Department o1" Marine Resources; and Boyd Kynard, U.S. Geologtical Survey,. for backgzround information and unpublished data. LITERATURE CITED Alleni S. 1 995. Out-of-comntol vegetation choking pails of the Charles. iRoston Globe. Boston. MA. July 3`)_I W5, t;eir;l, 31. 19S5. MLOasschsettts Coastal trOLit management. Ill: Wild TroLit ll. F. RI-cicic is0n uld i i R.H ilHaUIc d..* icd. "FIly Fishers wid Trout UInlimited. Vienna. gV'irhl.-l
- p. 1 1 42.
iielak, A. Iý 1994. Pollution and salmon: What's tie iroblem! in: A . Ilard Look at Some "uonoh Issues. S. Calabi and A. Stout (eds.). New onaaEnland Atlantic Salmon Manengecent ccnccrence. New Enigl and Salmon Assoc iation. NcburVporir MA. p. 200-212. Bigclow, H.B. and W.C. Schroeder. 1963, Fishe ofFtice. Guilff Marci U.S. Fish and Wildlilce Service, Fish Bull. 74.1-577. llackowel,. BF. 1996 i.coloc'v ol I)occuhle-Crested Cormorants in the 'cnohscot Rixer ancd nao Maoin. I'h dissertation, Univers ity of Mane,. Oconco 141 pp. Bowen-J.l. 1970. A history oi` fish culture as related to the develop-M len (? l'ishcry progia s "i. Fish. Scl )c. Spec Publ. 7:71-931 tBroxcn, B. 1987. Boston Harbor and Niassachusetts Ba,.-issuces. r icso lrces, and On.cccelcic i,. (ll: C, asialzollc 7 ,17. Pric, F'i111 xvnipos O )n Coastal nlid Occan Mani*-elnrit O. 1 Magoon. ii.
- Cinversc, r
). Miner. I..r Tobl i. 1). Clark. "tlnd G f)o-iicai ieds i. Vo. 3. Act-. Soc. Civil i-ng., New' Ycrtck p 09-3t10i. BuckeINy J. 198Q. Species Profiles: Icil,. Histocy and Env ironcntci l Requiruccments of Coastal Fishes and Invertebrates (Northi Atlantic): Rainbow Smelt. U.S. Fish and Wild. Serv., Biol. Rep. ,RN i.106) m ,i, d Acirmiy Corps o i. ihcc rsc's R EI.-,r -- i . I I pp. Carlson, C.C. 1988. --Where's the salmon?" A reevailuation ol the role .ofanadroiccous fisheries in aboriginal New England. In: Holocene Itilian Ecolocy in Northeastern North America. 13.1 Nicholas (cd.). PlenCum Press, New York. p. 47-80. Coffin. R.I ' T 1937. Kennebec. Cradle ofAciericans. Nexw York, Farrar & Rinehart. Cole, I.N. 1978. Striper: A Story of Fish and Man. Little, Brown. and Company, Boston an d Toronto. 269 pp.
- Isanie,
.S, i.G. Trial andi, J.G. Stanley. 1984. Species Profiles: Life I istory acd [cixvironniental Requiretrents of`Coastal I ishes and Invertebrates. (North Atlantic): Atlantic Salmon U.S. Fish and Wild. Ser. F'S/0.S.-8i11.22 and Army Corps of Engineers TR EL-82-4. 19 pp. DuBois, H.B.and S.P. Gloss. 1993. Mortality of juvenile American shad and striped bass passed throughb ( ssberer erusslox tur-bines at a small-scale hydroelectric site. N. Am. J. Fish. M-canage. 13: 178-185. Flag., L.Nand T.S. Squiers, Jr. 1991. Management, enhancement. and restoration of striped bass in the State of Maine, U.S.A. In: Proceedings ol'a Workshop on Bioloigy and Cuiture oi Striped Bass (Jilo,-one saxatilis). R.H. Peterson (ed.). Carl. Tech. Rep. Fish. Aquat. Sci. 1832. p. 23-28. 'Freeman, S. 1995. Low salmon runs worry scientists. Union-News. Spri-r'ield, MA, August 4. 1995. "
4-2 IRiN(; I:rielIcIand-K .I ).f. R dd i ind IJ. F. Kocik. I9'93. NInalie Survivial iii N-rth i Asic ric',o a., Erpe.. antic satimn: Eloinlcis oI" growth i and environment, iCES. IJ MNr. Sci. 50:481-402, lai es. I A. I987. A.ilaiiic salinon rcsiorucs Ii Ihc nortli eastc In United States and tile potwntial ctlccts of"acidification from aunrtsilcric dcposkia . Wa:ter. Air Soi Poll. 35:3 7--8. .lry, S.1 I., Jf.. Field. 5.1. Sbi,,c 1)M. Nelso, and Ni.F.N Monaco.
- 9194, I)iSirihitton and Auindanc ill FI' heS and hsvertchresCc in North Atlantic Estuarties 1. vl,. Rcpp No, 13, Nat
(.Oceanic and Anmospheric Ad ini.- Nat, Ocean Scyrv. Strategic Enviion. ,.\\s111-Div-Sflc f S M I.) 7'i pp Kiel"iýr. M.C. and I1 Kyvnard. 199t p, ing of the shortnose stur- -con it the Merrimack RiverN Mas-,achtIsetts. Trans. Amil. Fish. Soc t25: 179-186 Kimhball. D.C. and I,.W Stolte. 1978. Return ofthe Atlantic Salmon. Water Scturu. 8 ppI Krohn, W.B.. 11.1. Allen-JR Morina and-A.. Hutchinson. 1995. Double-crested cormorants in New England: population and management histories. Col. Waterbirds. 19 (Spec. Publ. I):99-109. Likens, GC-F.H. Borntann, N.iN-Johnson, D.W. Fisher anid. R.S. Pierce. 1970. EIl.ects, of" lores\\ cuttinSt and herbicide treatment oin lliltrie it hudnets ill the H-i uhbmard BIrook ", atershed ecvssteii. IEcol. MNnotior. 40 23-47 Nlathlir. DI R.-I3 I lcisec and. 1)D Robinsion.I 1994 l-i e-passage aortality \\f ojuvenilc Atlantic shad at a low-head hydroelectric dam. Trans. Am Fish Soc 123 108-Ill. NIclvin. G.I).. NI. Dadswccll and J-A. -IcKenz.ic. 1 L)2 Usefulness o1" teriistic and morphometric characters In discriminaitiilg piPtlth-tionis ofArierican shad (,-Iosa sapidi,,siita) (Ostreichithvcs. Cluperdae) inihapiting a mtarine eanvironment. Canll..1. Fish Act SciL 419(2': 266-28(1. Nboring. I.K. 1'986. Stockinc anadron~ous species to testorc or enhance fishCries. It: Fish Culture in I isherics N-namaemcit RIH. Stroud ted.). A-m Fish. Soc.. Bethesda. MD. p. 59-74. Mi\\riing,.. K. 19S9. l0occumtientltnmtn10 of" tnacco*nted-ltr asses of chti-look salhton tf-ont saltwater canes. ['ron. Fish-Gut. 5 1: 173-176. Molring, J.R. 193 Anadromotis stocks. In: Inland Fisherics Manageinent in North Atmierica. C.C Kohler and WA. I lubert, (eds.). Am. Fishl Soc.. Bcthesda. Matad. pi 553-80. Moring, JR. and K. Finlaysont 1996. Relatiomship Bietwecn Land Use Activities kind Atlantic Salmdoion (5/no Sot/cat: A L.itetatumrc Review. Nat. Council Paper Industiry fr Air, Stream Improve., Tech. Bull. 86 pp. Nloriitn,.. R, C G Caiiai.-.u-d.1) NI. Miiulen. 191i4. "l'.Icct-s of li-gins practices on fishes in streams and techniques Ror protection: a review of four studies in the United States. 1I: Rehabilitation of Freshwater Fisheries. I.G Cowx led.) Fishing News Books, Oxtbrd, U.K p. 194-207. Moring,.1,R,, J. Mtarancik. arid F. Gritl'iths 1995. Changes in stocking strategies for Atlantic salsmlon restoration arid rehabilitation in Maine, 1871-1993. Am.. Fi-sh Soc. Svntpos. 15:38-46. N-oring. J.R.. C. van den Ende, arid K.S. I-lockett. 1998. Predation oil Atlantic salnon smolts in New England waters. In: Smtolt Physiology Ecolo-y and Behavior. S. NIcCoriick and D. MacKitlay (edsl. American Fisheries Society, Bethesda, MD.
- p. 127-138.
Mullent D.M., CW. Fay and J.R Morming. 1986. Species Profiles: Life -I stories arid Enlvironmental Req utireitenits of Coastal Fishes and Invertebrates (North Atlantic): Alewi fe/Blueback IHerring. U.S. Fish attd Wild[. Serv 82(l 1.56) arid Arinty Corps of Engineers IR EL-82-4. 2 1 pp. M-lnrawski, S.A and C.F. Cole 1978. Population dynamics of'anadro-imoos rainbow smelt Osmerus smor-aox iii a MassachuisCtts river system. Trans. Atll Fish Soc. 107:535-542 Murawski, S.A., (_.1. Clayton, R.J. Reed arid, ClF. Cole. 1980. Movements of spawning rainbow smltelt. Osmerus mordax, in a Massachusetts estuary. Estuaries 3:308-314. New England Salmon Association. 1995. The New England Salhon Assoc. BlIt., Faill 1 pp. Nev,, Finglhd Sahl on -ssc cition. 1906 The Nc,u En21lod Sali lo Assoc. BuIll Itall. 4 pp. NNlFS (iNatioai NMI-ie Fistrics Ser;ievi )l92 01u. I-is at Oceans V S Dep. Comuterce-Nat. Oceanic arid Alinnes. Acdmil.- \\N" i',2tll on. D.( 14,l pp. NNFIES (Natimoia Marine iIisherics Service)e i90R, Essen.ial tlsh hahi-t!t t im d t inj,[ 1 tr Ailalhtic S`Ld -m I i 1 d i-cl script prcsentcd io New, IinIihitd I-iihercs.'1amnl'-cnlont Cioincfii Rideolt. S(G and I,.W. Stolte. 1988. Rcstoration of Atlantic sahltoin ilC Coh-iiicticcl l aid MNeri itick ri1C-i. macS p7-S in 11.. Stroud-ed. ICesCni and lI-toire ANtlantic Saithion Nanagemll N-ariine Rccreational Fisherice
- 12. Atlantiic Salmcoii Federation.
lpscmich, MA andNatidmiitCal Caiitii t ioN Marine Citser,-attin. Savttilah. Geortgia Rit/si, C.FI. 1953. iEastcrn liro k I root Polo latilons of Iwo' Nlaiilc Coastal Streams. Master of Science thesis, University of Maine. Orono 101 pp Rulifsoni R A. arid N-MJ. Dadswell. 1995. Life history arid population characteristics of striped lass in Atlantic Cainada.uirans. Ai. Fish. Soc. 124:477-507. Smith.1. 1622 See: Sinmith,.I. and P.I-. Barhouir 1986. The Complete \\,V5orks of Captain.lijhn Smith. 1550- 1(3 1. Uiiversits otf Nol th Ciioliml Press. SqUiers, I S.. Jr. 1988. Kennebec River Striped Bass Restoration Prograim. Maine Dep. Mar. Resources, Auigsta. 3 pp Sticr. )... ard 13. Kynard. 1986. Use of radio telectetry to deterini thie iiorttlits cf'Alanitic salilon siiols ptassCd throuigh a 17 NINA Kaplan turbitle at a luIv-head hydroelectric dam. Trans Am. Fish Soc 115:771-775, Stoloe. !L W 198 1. The Foru4otten Sainon ft lhe Merrimack River. U.S. Dep. SfI['lic Interior. 1U.S. (;ovt. ]rinting Office Washington, D.C. 214 pp. Stol tc. I\\V. 1 !986. Atlantic salmon. In: Autdubin Society Repirt. R.I.. DiSilvestrid (.cd. Nat. A;iduonli SoC.. Nev York. p.,v(,- 713. Stolte, 1. W.V 19 i9. Atlantic salliicit iestoCration in tie MNerrimack Rivcr basin. In A I lard ILook at Soille louhl Issues. S. Calabi aind A. stout icds. i N. New L-gland Atlantic Salhot Nlanagemeint Conference New Igliand Atlantic Salmon Assoc, Newtbutryport, MNA. p. 22-35. Taylor, R.E. and B. Kynard. 1985 NiMortal iy of jyuvenile ANlerical shad and hIlueback herring passed thrtough a low-:head Kaplan hydr,;-cilc crKi turbine l ions.I\\i1A . I tsh Sic I 4 :3i -43 5. Thoreaut B I) 1849 A Week on the Concord and Merrimack Rivers. Republished, 1998. PCeguiin Books. l'hurberg, F. attd F. Gould. this volumtitie. USFWS (U.S. Fish ainld Wildli e Service). 1980. Atlantic Coast Ecological Inv,'entory: Bostot*n. Inventory map. USFWS ([U.S. Fish and Wildlile Service) arid NMNIS (National Marine I-isheries Service). 1995. Statits Review fcr Anadroitmos Atlantic Salhon in the United States. 131 pp. Watt. W.D. 1988. M-,ajor causes artd implications ofAtlantic salhon habitat losses. In: R.H. Strotud (cd.). Present arid Fuiture Atlantic Salmon Management. Nicasuiring P'rourcss Toward International Cooperation. Atlantic Sanlon Federation, Calais, ME and National Coalition lkr NMarine Conservation. Inc., Savannah, GE. pp. 101-112. Weiss-Glanz, LS.- J.G: Stanley and,.I.R. N-oring. 1986. Species profiles: Life Bistory ald Einvironmental RItlteirements of' Coitmal Fishes and Imvertebrates (North Atlantic) Atmerican Shad. 13.S. Fish and Wild. Serv. 82(1 159) and Army Corps of fEgmineers 'R EI,-82-4. 16 pp. Wiener,.G. aid D.J. Spry. 1995. Toxicological significance of rner-cury in freshwater fish. In: Interpretintg Concentrations of Environmental Contaminates in Wildlife Tissues. G. I Heinz and N Beyer (eds.). Lewis Puiblishers, Chelsea, Michigan
PI)A 1 ;"NT I]FFE(" I S Chapter IV Pollutant Effects upon Cod, Haddock, Pollock, and Flounder of the Inshore Fisheries of Massachusetts and Cape Cod Bays FREDERICK P. THURBERG EDITH GOULD Nrational Ocespc and,-'1tmos72heric Achninist'cration -Vatio/?a/ ',Warine Fishieries Service 212 Rogeirs Avenue Nhil/tzr/. (iT 06460 LSA Nowhere is man's ecological naivele more evident than in his assul/ptions about the capacitO of/the atmosphere. soils, rive-s. and oceans to absorb p)ohlution. -Paul R. Ehi-lich (& :Ane H Ehrlich. 1970 INTRODU1CT ION Of the three possible impacts being discussed in this Volume (contamination, habitat alterations and overfishing), the effects of contaminants on demersal fish populations may well be the hardest to document. Catastrophic impacts of contaminants (e.g. oil and hazardous waste~spills) exhibit readily apparent effects, but are relatively rare and are localized. Thus, they probably have little effect on overall fish population structure. The more impor-tant contaminant effects are from chronic, low level exposures. As with catastrophic effects, even these chronic impacts are localized geographically. Contaminant impacts may be difficult to dis-cern from habitat alterations and overfishing because the overall impact may be due to the com-bined effect of low levels of.multiple contaminants (acting in an additive, synergistic or antagonistic manner). In addition, contaminant impacts may be masked by natural fluctuations in demersal fish populations due to such tactors as weather, variable predation, gradual climate change, food availability, temperature. salinity, and interactions among envi-ronmental variables. Contaminants may be adding additional stress to populations already stressed byi natural environmental Hluctuations, anthropogenic habitat alterations and overfishing, thereby con-tributing to declines in fish populations in some areas. This chapter focuses on the effects of four major pollutant categories (metals, petroleum hydrocarbons and PAHs. PCBs. and pesticides), each of which contain individual contaminants that are listed on the Environmental Protection Agency's list of"priority pollutants" (Table 4.1). Toxicological impacts are assessed on several com-mercially important Northeast groundlhsh species including cod, haddock, pollock and four flounder species, of which cod and flounders have been the subject of considerable research. The European lit-erature abounds in both experimental and field work with the Atlantic cod, Gadus morhua, from which the more relevant reports have been abstract-ed for inclusion here with American and Canadian papers. In the American Northeast, the winter floundel, Pseudopleuronectes americanus, has also been the focus of much experimental work, and is perhaps the most widely studied marine fish with respect to pollutant toxicity. It is widely distributed, is highly visible as an important commercial and
441* Table 4.1. "Thc US. Environmental Protection Agiency's Prionty Pollution list (U.S. EPA, 1984). Contamimaints marked with an asterisk have been routinely nonitored since 1986 in sediments, marine mussel tissue and groti .tish tissues by NOACA's National Status a"rd lTrenIds Program (Bendthic Surveillance Project (NOAA,,NS&T. 2000) and Mussel Watch Project: Lanenstein and Caimtillo, 2000). Metals ?W, As*' B\\. Cd(*. Cr*i tu*. II*. Ni*, Pb*. Sb*. Se*. TI. all congeners and Arochlors PAllIs* acenapthiene*. ace naphthy lene* anthracene*. be nzo(ahailthrace lie! *, benizopur yelic, benzo(a)py rene*. be/z.o(b.kklHuroranlhiene, hys ie* dibenzea.h ianthracenc* 1'tlnranthicne*. fluoreie*i, iCnno-p\\yrene*; naplhthallue*. phenanthrene*, pvrcne, Pe:sticides aldrili*. chliordane*. DDTll. DDE)*. )DD*, dieldrin*, eldosulplihans, eidriin. endrin aldehyde, heptachlor*, hep-tachlor epoxide*, hcxachlorobenzene*, ltindanes iBtIC *, toxaphiene Other haloe*nmed compounds bromniolnrii carbon tetrachIlride, chlorinated benzenes. chlorinated naplhlhalenes, chloroalkylethers, clihIobnenzene, chlorodibromomethane, chloroforin, diclichlorobenzenes. dichlorobeizidine. dichhbtiethane, dichhl.rhromnmehane, dichloroethylenes, dichlorophenol. dicliloropropaiie,. dichloropiopciic., dichloropropylenc. dioxins (TCDD,. haloethers. halometlhanes.l hexachlorobutadiene. hexachloro-ci c lokiexailes, hachii racyc lpentadicne, hexach lotietlianei methylbromide. methylchloride, methylchlorophenol, methylenechloride. pIentaehlorolphenol, tetractilorobenzenc. tetrachloroethanes. tetrachloroethylene, tetrachlorophenol, Itichlorinated ethaics. trichloethyene, trichlophenol-vinyl chloride Phthalates butylbenzylplithalate, dibutylphtlialate, diethylphthalatc, dinethyl phithialate, die thyl hexylph liat ate. ph thalate esters N itro-compounds dinitrophenol, dinitrotoluene, dinitro-o-cresol, nitrobenzene, nitrophenols, nitrosamines. nitrosodibutylaniine. nitrosodi-ethylamine, nitrosodimethylamine. nitrosodiplienylamine. nitrosopyirlidiae, nitrosodipropylamine Other compounds acrolein, acrylonitrile. asbestos, benzene, benzidine, cyanide dimethylphenuol. diphenylhydrazine, ethers, ethylbenzene, isophorone, phenol, toluene recreational fish. is easy to handle iti the laboratory, and is. readily collected from contaminated coastal ateas. -hIle nuttiiber of field and laboratory reports of the effects of pollutants ot the other five species Ithaddock. af/aul'u; LIJIiOl "'I'lUi\\mitM pollock, l//olhines vil/its: yellowtail flounder, /elt'oneclces i!C/,';'i w-o zwtoi ,.:\\ erican plaice. bH/1',,ot,!ov.i 5uc'S P/a essouei/s; witndowvpanie flounder. Scn.phhha/mils aquostis), whether examning cause-and-efltcts, circumstantial evidence, or even engtaging in iniformned speculation, is sparse. Our aint here is to sutumiarize the various types of toxicological effects, both lethal and sublethal, that have been shown to occur at the organismal, tissue, cellular and subcellular levels of biological organization. This review follows the progression of research froii the laboratory where toxicity was demonstratecd through carefully controlled laboratory exposures, to the field where laboratory observa-tions were confirmed at contaminated field sites. While much of the early laboratory work used high, often environnmentally-tunrealistic concentra-tions of contamiinants, these studies have neverthe-less been useftul in determining the initiation, pro-gression, and mechanismts involved in many adverse health effects observed in the field. Additional laboratory studies showed effects upon very sensitive early life stages as well as effects upon reproductive processes. The next critical stage, linking these laboratory. field. and reproduc-tive biology studies to population effects, has been attempting to demonstrate that pollutants do have a measurable effect upon fish recrutitment processes and thus effect population structure. This has been a difficult and elusive effort. The multitude of potential stressors in the environment (i.e., temper-ature, season, predators., parasitism, siltation, food availability, to nam e a few) in addition to the possi-ble antagonistic and synergistic effects of multiple polltUtants, both organic and inorganic, found in contaminated habitats, clouds the determination of specific effects of pollutants on fish populations as a whole. Mathematical models are being developed to consider the interactions of these multiple factors with contaminant effects, but the definitive answer is still some time away. This at least partially explains the lack of information on direct effects of pollutants on fish populations and communities.
t).I'MAJ *Ni FFvlz, i5 45) Co.i'..mI'INANT DIsTIhIIlIF'IoN IN, FINIISII The ialie v / '/ssochise'ts' niarine Ur, vil(*ulC is (leIalciLel Pollut'ion is inptclinlfish and shellfish health and illnacing isleries. hi; s-enderini /ish and s//ei/i/s!i iii somenc locaiion isinl o cal Uo ci'eating the unu'arr/ aud pi!h/ic pekrieplion thal all seafbod shouti be shaumneJ -t114-DDAJ 1985 Various metals., pesticides, polychlorinated hiphe vIyls (PCBs). polycyclic aromatic hydrocar-bons (PA -Is) and other petroleum hydrocarbons have been measured in fish taken fiomn the wild (lable 4.2). Elevated pollutant levels in fish tissue are, at tile very least, an indication of habitat con-tamination. Temporal changes in contaminant body burdens have been diocuimented. at least fot some locales (e.o. Canadian G inorhuo, Freeman and lithe, 1984; Misra et al., 1988; Norwegian G inor;ha, Skfre et al., 1985). Decreases in environ-me.nial eXposure 1o these contaminants are geenerallv reflected in declines in fish contaminant bioburdens over time. Higher concentrations of metals in seawater and sediments have generally, although not univer-sally, been correlated with higher concentrations of metals in various fish tissues. Geographical differ-ences in concentrations of Zn, Cu. and Cd in Atlantic cod muscle,.for example, reflected local Table 4.2. Examples of contaminant bioaccuMulation in deinersal fish species from the western North Atlantic. ............... ---i-i-s----- Species of Fish Examined I ilanlic cod InUWIc Collection Site Balhic Sea Norway Newlioundland & Labrador 1 li.-ntic cod Atiltic cod. nknerican plaice i~tlantic cod lAtlantic cod H addock Toxicant Ileasured Reference .i niicI livnr, usleiC liver n uiscie CI Cd. Zn 7 'cniitii et al.. 1982 1-ig .JulshaIm in et al.. 1982 As Kennedy, 1976 Nova Scotia, New LBrunswick -F DDT oreanoctiloriics t" IIa(Iiad off shore Sins et al.. 1975 Friemanii and Uthe, 1984 Capuzzo ct al.. 1087 PCB Winter flounder muscle NY Bight. Hudson Shelf various metals Reid et al.. 1982 Winter f]otndcr liver Long Island Sound I Cu. Mn, Zn Greig and Wenzloff. 1977 !Winter flounder liver Boston Harbor various metals MacDonald, 1991 Winter flounderi muscle, liver NY B3ight PAHl. organochlorines MacLeod et al.. 1981 Winter flounder whole body New Bedford Harbor PCB Connolly, 1991 Winter tlounder liver NY Bight PCB Reid ct al., 1982 Winter flounder onad liser Long Island Sound PCB Greig and Sennefielder, 1987 Winter flounder liver New Bedford Harbor PICB Elskus et al.. 1994 = ioundera liver Long Island Sound PCB. various metals Greig et al., 1983 flounder W~indowpanet Jinder Imuscle Delaware Bay lae Gerhart. 1977 flomunder
4 6 li I ý T; R iý, C:: ; I: 1 concentrations In seawater (Perttihta et al., 1982). American plaice collected oft Newfoundland and Labrador had arseic concentrations in muSCle tissue that were similar to levels in sediments, much higher than those totind in Atlantic cod, redttish (Sebasics narimits) and turbot (ReIinl'lcdlius hipo gllossoi(Js) fhorn the same area, but lower than concenirations
- in the local shrimp upon which they prey (Kennedy. 1976).
In contrast to these two examples where metal body burdens correlated with environmental con-tamination. metal body burdens in winter flotnider did not reflect the high metal levels found in the sediments of the more contaminated sites sampled from the New York Bight and Long Island Sound (e.g. Christiansen Basin, and thed"Nludhole" 310 kiu SSE of the Basin) (Reid et al., 1982: Carmody et al.. 1973). In a comparison of two sites in the west-to-east pollutant gradient in Long Island Sound, Hempstead Bay (westernmost) was considered heavily polluted comnpared to \\vaters off Shoreham NY (mid-Sound) based on metals in sediment data. yet Cti., Mn, and Zn concentrations in livers of win-ter flounder were twice as great for Shorehaam as For Hempstead (Greig and Wenzlof 1977). The absence of a correlation between metal concentra-tions in tissues and the environment was also apparent in Gerhart's (1977) study of HIg in eleven fish species incltiding winter flotinder from Delaware Bay, and McDonald's (1991 ) review of data on winter flounder fiom within Boston Harbor. Wintei flounder is a pollution-tolerant species that migrates between shallow and deeper waters sea-sonally, and therefore may not reflect contaminant levels from a single site. LiPOPHILIC CONTAMINANTS Lipophilic contaminants such as chlorinated pesticides (DDT, DDT analogs, chlordane, dieldrin, etc.). PCBs, PAHs and other petroleum-derived contaminants, have the ability to accumulate in the lipid-rich tissues of fish. For example, DDTs were measured in cod liver in quantities far exceeding the amount present in the flesh (Sims et al., 1975), a fact more important to the health of the fish than to the consumer of cod flesh. In general, concentrations of these lipophilic contaminants in fish tend to correlate with contami-nant levels in the environment. Elevated levels of polycyclic oriariochlorine pesticides were .i found ill livers of male American plaice sampled in the North Sea neai areas of major rive'rile input and other souices of inthriopogenic pollution (Knickmeyer iand Steinhart, 1990). Pesticide levels were also elevated in winter flounder from a tribu-tary of BuzzaiIrds Bay MA, indicating significant levels of contamination in this area (Connolly. 1991 ). The highest concentrations of pesticide con-taminants Were found in coastal harbors and indus-trialized centers (MacLeod et al., 1981 ), whereas offshore areas had very low levels (Connolly, 1991). Similarly, levels of PCB congeners in liver samples of male and female Atlantic cod reflected a decreasing PCB pollution gradient away from the motith of tlle G lonmma, Norway's largest river (klarthinsen et al., 1991 ). Offshore haddock fish-eries had very low levels of PCBs, plresumiiably reflecting the low PCB exposures as distance from the mainland is increased (Capuzzo et al., 1987). PCB concentrations were higher in \\vinter flouinder gonad and liver samples from the more polluted sites in Long Island Sound' (Greig and Sennefelder, 1987). although no relation was found between windowpane flounder liver concentrations of PCBs anid a Long Island Sound pollution gradient (Greig et al., 1983). Fish may obtain these organic contaminants not only via the soluble phase, but also throutgh ilges-tion of contaminants present in or bound to prey items, as well as by contact or ingestion of contain-inants bound to particles and sediments. The rate of uptake depends oil the lipophilicity of the coim-pound. Winter flounder exposed to crude oil-spiked sediments for 4 months accutimulated more of the low molecular weight PAHs than the more lipophilic, higher molecular weight compounds (1-Hellou et al., 1995). The more lipophilic the con-taminait, tlhe more important is the ingestion route in uptake. Connolly ( 1991), for example, demon-strated, using a food-chain model, that uptake of soluble PCBs across the gill of winter flounder was exceeded by dietary uptake of PCBs. Contaminated prey species provided 80-95% of the PCB body burden. Assimilation efficiency of PCB declined fromn high values for trichlorophenyl to low values for the more highly-chllorinated (more lipophilic) congeners (Connolly, 1991). Some of these lipophilic contaminants are quite persistent in the environment, as reflected in
4 47 Table 4.3. Toxicological efeccts and diseases possibly associated with concentrations of toxicants ill fish. Potential correlictions made between body tissue burdens with suiblethal toxicological elfec ts. .\\tl tic cod ilivcr kidney., IBahlti oa sky Ic ton I Atlatic cod live !Nort Sa Atani co It i io ocItxicant iAssiciated Mecasure of ojt Rel'erence Meiasured cd !ýkeletal dceIoniitile, I oneL & l.)elide'cl. 198i I PC3 7Tcus~xudrni!Stork. 1983 I t)t'te.~ vi I 1)8.1 I lI...-. jAtlantic co'd iliver , allan1tic cod behavior A'tklmic IcCod 5i I 1 Hal htx I hrbor iassuncd. ýlnty change' in liver ctrecian tal-.. 1981a.b ml talts. oreanies 1 c....u.. PA I I prasitic ni16o_ Ics has r i aii anl 1900... Attatitic cod liver, testes tab exposUre IPCB 'reduced strvival & reproduction Sangatan-g et at., 198 1 [ellowtiail epidermis INY Bight iambient scmxaterifin erosion Ziskowski et at.. 1987 flounder skeleton t ..i iYellomtc il ive.. r. skeleto ein i i N.. parii.- si is. i iver lesions. sk.. eta I Dcspres-tatanko et at 1 982. ,fnlu,,, d.r ilatda ic ,aborm,alitics .tilichei:iiio c l.. - 1986 .I.& St1.11-iii ieSi i*d v l II-look ft Itv C... lc... ii-c ih-iT, ijir St l t Coill t li Ii. la ts i cIIIl i a
- i.
1.*a - i tier laounder NI Wi Lnter flounder epidermis, liveri Y Bight * . or 1Dr7I imcireased livcr size, fill erosion Sherwood. 198) W iter i~lPTde/ ive,,, Bed Ioi c~t -r IC 3 iiiciesed 1w-151 protein (but to WEskus edad.. 1989 (t]a, FN puu. It 'de in, FRO*t) Wiiirte r tionder gonad. larvae, ILon" Isand IPCI Ilowered iepiroductive rates: sin larvaeII NeIs-on et al.. 1991 einbrvos 'SoutnedI enbrx.nib l ibnonnii itie Winier flonder [egs. .New led lo,*rd [- i........ allem In ta \\ e 1 Black c _al.. 1988 AiWinie" floundcr liver Boston I larbor IAltI liver tuinor & other liver ttiteltaitao & Vo-lke 1991: piiaa"iMookare It) I9 Sntloh.\\ litCt -:iI. i p-a tho lo gies !.M o r 199 1
- lo tc al I liverb:
T____o,, & O'Cokt or 1991. \\\\inttr flounder 'epidermis, sktt New York Bight ambient seawaterif in erosion Ziskowski c tl.. 1987 "irt~. later clO ~i tic r i e I t. eggsI.oit, Isilaitnd ittibiciti Sctv aiter , C"" C~tt*,t.ui1x ..ell itncctisi cli -i a c tiev C l :i.. 1991 tiSold mo'sotnc dci.irise, sl(oxer de,. i I t\\Vinter floundcr liver, bloodt New t laven Cl. I metals. t.tBs liVCr lesion)s. blood cell ahnorm alt-ticrig & WcnzIoll. 197;7. cells Lonslaid
- ities, liver NA dattiage. liver nea-Greig & Sennel'elder. 1987.
Sound. NY liuhb
- plasi5 (rcnluniid CL al.. 1901.
under blood cells cNY ight A. NJ. ant eoncleii in rI fi-Lotugtes & lebert. 1991: .tmrte oun d cells coastal it-ambient seaiwateriervthiocvte mutations and !LongWell etal. 1983 _p._- flounder Atlantic i microntcleiit vvinter flounder blood cell Ct Boston HI arbor. NEinambient seawaterlhigher no. immature eroflracetes Daniels & Gardner. 199 \\\\Winter flounder lar vae ]\\\\;r Narra-anseut Bt.ambient seazsater s, votlk-sac larvae: hvr rate survivalButcklev et al.. 1991 Minter liounder liver, plasita, Boston Harbor ambient serwater iedUcd: ttcpdtici pecttral lin ascorhicICarr ci at.. I991 brain, muscle, acid conc. helpatic glycogen. lip: I epidermis Iplasma glucose: brain serotonin. to-Ireimnelthrie_
- ttitniO acid conte otiscet 1Wi rte-r fItotdei I liver If alifax I larbor lambient seatwateriliver
- necrotienic eflects liepatocyte irTax ct al., 1991 ibasoptmitia, nmacrophageaiggrega-ution, hepatic epithelial vacuolation) t Wier Ilounder I'er Lon IsIad S0Und biet seiaers t
hIo _-.1)N A a Ier. iii liver Gronhtild et at., 1991 Witter hitnder whole body Ilab expostire D)DT & dieldrin reduced stirVival of'embr-os -[Siwth & Cole. 1973 VIndoxtaolp,*e Ii. blood Long Is*a*ad SOtUndibet s.aw.ieri*inceased I-lt & hietotglobin Dawso,. 199(0 Wiitdo tpane, New Yorp Bight tambient seawvater fin erosin OConnor. 10/6 Yelloxwtail, & skeletotit \\Vinter flounder 1-4 Windottpane eLong Isladteuntiaoien abnornIiities in eggs LongwelI et tt 1992 Ifloumnder ewtrnloi
'48 itR*:~i 4G ; temporal monitoring of iish tissues. Most organochlorine compounds in livers of cod caught off the east coast of Canada ii 1980 showed no change in concentrations over tile previous S yeais, with the exceptions of DDT and the PCB group, in which there was a general decline between 1972 and 1975. with no significant change thereafter (Freeman and Ulthe. 1984). Following a 1972 DDT ban in Norway. cod liver samples showed decreas-ing concentrations of DDT: 10 years after the ban. the highest level of cod liver DDT was about one-third of the corresponding 1972 residue level (Sk~re et al., 1985). The persistence of lipophilic contaminants in fish themselves is related to several factors, includ-ing the conlai inant's degree of lipophilicity, the size of the orgranism's fat stores, the organism s abilitv to metabolize the contaminant, and the organism's seasonal turnover of fat. When exposed to a radiolabeled PAH (benzo(a)pyrene) and a PCB congener for 24 h, for example, cod eggs and newly-hatched larvae accumulated both fr'om the seawater. After being moved to uncontaminated seawater, the yolk-sac larvae showed no apparent eCliminatioii of the more lipophilic compound, the PCB, although there was a clear elimination of some benzo(a)pyrene (Solbakken et al., 1984). PCB levels in winter flounder liver were signifi-cantly correlated with body fat content, although fat content itself did not correlate with the contami-nation gradient (Reid et al., 1982). Haddock and cod from aNorwegian flord had clearance rates for DDI and PCB that were slower than those found for wolffish, sea scorpion, a European wrasse, and lemon sole. While demonstrating interspecies dif-ferences in contaminant metabolism, the slower'
- clearance of liver DDT in cod as compared to the other species examined may also be attributed to the substantially higher fat content of cod liver (Skhre et al., 1985).
Fat stores are closely tied to the fish's seasonal cycle of reproduction. PCB levels in female cod also varied seasonally (levels in Sept./Oct. greater than corresponding levels in June and Nov./Dec.),. although no such effect was seen in male cod (Marthinsen et al., 1991). Similarly, work in Long Island Sound showed concentrations of PCB in winter flounder gonads to be highest (0.73 i.tg/g wet wt) in the months just before spawning, as compared to levels in other months (0.056-0.36 pg/tg; Greicz and Sennelfelder, 198/). After spawning, PCB concentrations In gonads decreased to very low levels (0.03-0.08,ttg/g). In contras,. F.lskus et al. (I1994) f1ound that the content and concentration of PCB congeners in winter flounder liver taken from New Bedford Harbor fish, did not correlate with either sex or reprod ucti ve state. H owever. they cautioned that the hiich tissue concentrations of PCBs obtained at this extremely contaminated site may have obscured sex and reproductive condition di fferences. TOXICOLOGICAL E I'FEC'S OF CONIAM INANTS ON FINFISI. 4S LI"'li'dC a wc/)Oll 'I'S t117 Ca Ive lInc? ; club, the chemical barrage has been hurled ugain.t the fabric of life - a fahric on the oie hunl delicate and cleslruclible, on the other MiraeulotlsHIv lough and resilient, and capable ofstriking Nack in unexp)ected ivais. -Racha/ C!(arson, 1962 Bioaccumulation of contaminants does not nec-essarily imply that the contaminants are having an adverse effect on the organism. Nevertheless, there are imumerous examples to show that both laboratory and field exposures to various metals, pesticides, PC.Bs, PAiHs and other petroleum hydrocarbons do in fact elicit toxicity. In some cases, toxicity has also been linked to elevated tissue bioburdens of these contaminants (Table 4.3). METAL S Each of the thirteen metals listed as EPA priority pollutants (Table 4.1 ) varies in toxicological potency and mode of action. This differential toxicity is best illustrated with data on winter flounder. The order of sublethal metal toxicity (2-5 mo, 10 pg/L metal) for adult winter flounder was CdCI?> HgCl> AgNO3 (Calabrese et al., 1977). Metal exposure either elevated (Hg) or depressed (Cd) gill respira-tion. Mercury, but not cadmium or silver, induced .statistically significant hematological responses.
r()iA..Y~flF! 49 Cadmi nut, hOWevCe, was the most potent inducer of transcription of the oene for metallothionein (('han et al., 1989,lessc ni-Eller and Crivello, 1998). the principal function of which appears to be the main-tenance of homreostasis for the essential trace metals zinc and copper (Roesijadi and Robinson. 1995). Exposnre ol w'inter flounder to low concentrations of Cd indluced several signilficant metabolic responses:. I ) the ability of magnesium to promote enzyme-substrate binding in enzymes such as glucose-6-phosphate dehydrogenase (G6PDH) was impaired; (2) G6PDH. wasinduced in gonad, heart, and skeletal muscle; (3)) kidney tissue in particular showed an increased expenditure of energy (for synthesis of enzymes to maintain homeostasis under subletlal cadmin iui stress) and a loss of sei-sitivity to normal metabolic control (maCnesiuim s enhancementof enzVyle-stibstrate affinities); and (4) in the liver, glycolysis and shunt activity increased (Gould. 1977). These same phenomena weie observed in mercury-exposed Hlounder but to a lesser extent, whereas silver-exposed flounder showed very little effect (Calabrese et al.. 1975, 1977). Metals initiate a number of additional toxico-logical effects in fish. Acute exposures to high metal concentrations as well as chronic exposures to much lower concentrations can elicit morpholog-ical changes (e.g. lesions in winter flounder and haddock olfactory organs followingi 18 1h exposure to 500,ug/L Cu, Bodam mer, 1981; abnormal swelling in windowpane flounder gill tissue follow-ing 2 mo exposure to 10 ýtg/L Hg, Pereira, 1988). Important metabolic enzymes can be inhibited (e.g. winter flounder Na. K-ATPase inhibition by Hg, organic Hg and organic As, Musch et al., 1990). Various metals can interfere with ion transport across membranes (Hg and niethymercury can inhibit Na transport, Renfro et al., 1974; Farmnfanrmaian et al., 198 1; Dawson, 1990; 1H1g, organic Flg and organic As can inhibit K transport, Venglarik and Dawson, 1986; Musch et al., 1990). Methhlinercurv can increase the energy expenditure for transepithelial electrolyte transport in winter flounder gill and intestinal tissue (Schinidt-Neilson et al., 1977). Ionic Hg, organic Hg and organic As diminish the absorption of some amino acids in flounder species (e.g. leucine, Farmanfarmaian et al., 1981; tyrosine, Musch et al., 1990). In general, early life stages of fish appear to be more susceptible to toxicity than either adults or membrane-protected embryos. LC., concentrations (the concentration of a metal that is needed to kill 50"% of a test population) are typically higher for adult fish and non-hatched embryos (U.S. EPA. 2000). Nevertheless. high concentrations of metals maiy effect hatching success. Concentrations ofSil-ver above 54 ti L in aflow-through bioassay (18 d, 54 - 386 tu/L) produced greatly reduced percent viable hatch in waintei Hlounder embryos aiid caused larval mortality (K.lein-MacPhee et al.. 1984). Embryos exposed to 180 and 386 j~tg/L hatched earlier than those exposed to lower concentrations. and many had physical abnormalities. Mean total length and mean yolk-sac volume of hatched larvae tIro the 386 uoiL silver exposure were significantly smaller than the lower Ag exposures. In contrast to Klein-MacPhee's experiments, the percent viable hatch of winter flounder embryos was not effected by silver (0- 180 ui/L) but was decreased by cad-miulml (1,000 jtg/L); addition of silver, however, decreased the toxic elfect of cadmium on the viable hatch response (Voyer et al., 1982). OiL Much of the toxicological research on commer-cial fish species was spurred on by concerns over oil spills. Petroleum pollution has been shown to correlate with a variety of adverse behavioral, physiological and morphological parameters. Cod avoided'concentrations of total petroleum hydro-carbons down to 50 ttg/L, either in solution or as an emulsion (Bohle, 1983.). In the laboratory, detec-tion thresholds for behavioral changes (snapping, darting, coughing, and restless swimming activity) in cod upon sudden exposure to oil compounds were observed at concentrations as low as 0.1-0.4 .tg/L (Hellstrom and Doving, 1983). Various fish species, chronically exposed to the water-soluble fraction (WSF) of crude petroleum or to oiled sedi-ments, exhibited reduced growth, food consumption and body condition, depletion of energy stores, reduced gatmetogenesis and spermiation (release of mature sperm r-om the Sertoli cells), liver hyper-trophy, splenic atrophy, impaired imImune response., and morphological abnormalities such as gill hyperplasia, filament fusion,. increased skin pig-mentation, hepatic granulation, increased gall-blad-der size, increased numbers of mucus-producing
111) R w z>! ý ~m-I epithel ial cells, capillary dilation, delayed sper-natogenesis, and an increase of nielanomacrophage centers in the spleen and kidney (Khan et al., 1981: Dey ct al., 1983: 131urton et al.. 1984. Khan and Kiceniuk, 1984; Kiceniuk and Khan, 1987: Payne and F'ancev. 1989). Chronic exposure of cod to crude oils., it was concluded, results in severely dis-abling lesions and reproductive impairment. Yet. mortality due to oil spills among large free-swim-nig ic nsh has hardly ever been recorded, Bohle (1983) concluded, because they can move away fron containimated areas.. Exposure to petroleum hydrocarbons typically induces the synthesis of sevet al cellular enzymes, the Mixed Function Oxidase (MFO) enzymes, that. mnCtabolize Soi e ol the1.se conpounds. The most studied of these MFO enzymes are the group of Cvtochrome P-450 enzynmes (e.g. aryIhydrocarbon hydrolase (AHIH), ethoxyresorufin 0-deethylase (EROD)). Several genetic isoforms of P-450 enzym es have been identiflied in western Atlantic fish (Wall and Crivello, 1998; Nelson, 2000). While P-450 enzymes are constituitive, elevated levels are biosynthesized "on demand" to catalyze the breakdown of many organic pollu.tants. Cod and haddock captured close to oil platforms showed significantly higher levels of Al-Il in their livers than did fish caught in areas well away from oil activity (Davies et al., 1984). These data were the first to indicate that oil in sediments around oil platforms may be bioavailable to fish in the area, probably via the food chain. Chronic exposure to petroleum WSF' in the laboratory produced an oil-inducible MFO activity that was elevated 4 times higher in the liver and 3 times higher in the gills than in control fish (4 mo, 300-600 bIg/L; Payne and Fancev. 1982). Winter flounder, exposed for 4 mo to oil-contaminated sediment that was weath-ered for a year had levels of hepatic Cytochrome P-450 that were seven times greater than unexposed controls; fish exposed to freshly oiled sediment (I liter oil in 45 kg sand) exhibited a thirteen-fold P-450 induction rate (Payne and Fancey, 1982). However, examination of winter flounder collected firom the site of an oil spill in 1984, and from a ref-erence site showed that reliance on the measure-ment of liver MFO parameters alone could lead to false negatives in biological monitoring programs. The kidney provided statistical differences in ele-ments of the MFO system between control and oil sites, whereas the liver did not (P'ayne et al., 1984). Nevertheless, the same research team, using oiled sediments under a control led laboratory exposure, later found that biomarkers indicating exposure to oil were (in order of decreacsing sensitivity): liver MFO activity, liver condition index (liver wt/total body wt), kidney MFO activity. spleen condition index, and muscle protein and water content. Liver lipid and glucose levels and condition indices for uLt, kidnev. testis and whole fish were not affected at anyxexposure level (Payne et al., 1988). Induction of these.enzmnes in the liver typically precedes liver damage, although both liver hyper-trophy and MFO induction may occur simultane-ouslV. The level of exposure to oil at which liver hypertrophy continues to increase while \\1IF()" activity begins to decrease has been called the "*point of crossover." It may represent the point at which the detoxication mechanism is overwhelmed (Hutt, 1985"). As indiclaed eatrlier, early life stages are often more susceptible to contaminants than adults. Yellowtail flounder eggs collected during the first three days following a gasoline spill near Falmouth MA had an 81% mortality rate (13 of 16 eggs died; Griswold, 1981). Many of the cod and pollock eggs collected shortly after the Argo Merchant oil spill (during the pollock spawning season) had oil adhering to the outer membrane and showed evi-dlence of cytological abnormality of the embryo's cells and nuclear configurations indicative of cell death coupled with division arrest (Longwell, 1977). In the laboratory, cod eggs and larvae exposed to WSFs, suspensions of crude oil, cuts (oil distillation fr'actions), and some low-boiling aromatics exhibited increased mortality, reduced growth, and several morphological abnormalities: delay and ir:egtlarities in cleavage and develop-ment, poor differentiation of the head region, mal-formed upper jaw, protruding eye lenses, abnormally bent notochord, and various levels of inhibition of hatching and assimilation of yolk (Lonning, 1977). Both survival and feeding were further impaired following photodegradation of crude oil compo-nents (Solberg et al., 1982a). Kfihnhold (1974) found through laboratory exposures that cod eggs were most sensitive to crude oil during the first few hours post-fertilization. Oil retarded development, delayed or prevented hatch, and induced significant mortality by 10 h post-exposure. Those larvae that
pm I
- ,.I r I
51ft~r; did hatch showed a high level of abnormal devel-opment or abnormal swininning movements, and died within a tew days. Further work with early l ife stages confirmed the variety of adverse morphological changes. Developing cod embryos exposed to Ihexane extracts of sCa-suriface linicrolayer from 5 marinas located in the North and Baltic Seas sho\\wed signif-icant embryo mortality as well as severe deforni-ties in live hatched lartae at two of the sites (Kocan et al., 1987). Other Studies noted a signifi-cant decrease in growth rate (Tilseth et al., 1981) and a toxicant concentration-dependent reduction in feeding (Solberg et al.. !982a.b.c). Such oil-induced disturbance of physiological and behavioral patterns would redtice leeding ctpalbi litV at thle onset of feeding, with consequent high mortality in the field. Morphological disturbances that result in the ultimate death of the larvae, may in turn lead to serious effects on the fish population in the polluted area. Exposure of cod eggs to the water-soluble frac-tion (WSF) of crude oils (50-150 ttg/L) did not, however, significantlv affect surface membrane permeability, nor was osmnoregulatory ability of the embryo affected by these ecologically realicstic con-centrations.(Mangor-Jenseni and Fyhn, 1985). The WSF of North Sea crude oil (50 pgiL ) had no effect on oxygen uptake of the,._os. vet stronoly' suppressed oxygen consumption by cod larvae at the time of final yolk absorption (5-7 d post-hatch), when the larvae begin to feed (Serigstad and Adoff, 1985). Crude oil extracts can also affect the ener-getic processes of cod eggs and larvae in addition to causing structural and developmental damage. One such.extract (8 mng/L total dissolved hy'drocar-bons and dispersed oil) had no significant effect Upon oxygen uptake in late-stage cod embryos and larvae with functional yolk sacs. Early embryos and starved larvae however showed reduced Oxvygenl consumption when placed in the extract, and the starved larvae became narcotized (Davenport et al., 1979). A number of behavioral effects were also docu-miented. Larval cod exposed to sublethal amounts of the WSF of crude oil exhibited reduced growvth, lower specific weight (neutral buoyancy), reduced feeding ability and swimming speed, and a serious disturbance of the swimming pattern. Larvae exposed to 4. I mg/L or higher did not recover their feeding ability within 24 h of transner to clean water (Tilseth et al., 1984). Cod larvae less than 20 mm are the size most hatlried by exposure to a 50 + 20 utg/L W SF of oil (Foyn and Serigstad, 1988). The effect of a I-to 2-h exposure of cod egos to the WSF is not acute but instead long-term, leading to starvation of the cod larvae. [lhere is no recovery from tile effects of exposure to the oil WSF when cod eggs or larvae are placed in clean seawater (f'loyn and erigstad, 1988). Goksoyr et al. ( 1991 ) exposed cod eggs, larvae and juvenile cod to a WSF of-North Sea crude oil (1-6 wk., 40-300 ttg/L_) and examined them for induction of Cytochrome P-450 enzymes. Althouglh the exposure began durino the egg stage, induction response was delayed until aftt hatchittg. I he P-450 induction response wvas dose-dcpendent, and recovery in clean water resulted in normalization of P-450 levels (Goksoyr et al., 1991). 1mlmuno-chemical response (i.e. induction of the specific Cytochronie P-450 I C as deternined by intinuto-chemistry) in the liver of juvenile cod and in hlonlogenates of whole larvae was dose-dependent. Larvae and juveniles that were allowed to recover in clean seawater showed a P-450 decline toward control levels within a few days (Goksoyr et al., 1988). Laboratory exposure of juvenile cod to crude oil and oil dispersant produced significant changes in physiological parameters (heart rate, respiration, gill ventilation rate and amplitude) that did lot occur until pollutant concentrations were close to lethal levels (Johnstone and Hawkins, 1980). Because oil dispersants are often toxic to early life stages of fish, they are often studied together with oil as contaminants. The higher the aromatic content of an oil dispersant, the greater its toxicity to unfed haddock larvae (Wilson, 1977), Larvae were more susceptible to a dispersarit's toxic effects immediately subsequent to first feeding. Numerous dispersants have been developed, how-ever, that are 2 to 3 orders of magnitude less toxic than the kerosene-based dispersants available earlier. PA H s One component of petroleum hydrocarbons, the PAHs, has received additional attention because of its known ability to induce various MFO enzymes (Solbakken et al., 1980; Foureman et al, 1983; Stegeman et al., 1987). In male and female
5 -) C! { : winter flounder collected over a 2-yr period fromn a relatively non-polluted area in Nova Scotia waters, sCeasonal variation (about ten told) in hydrocarbon-inducible P-450 activity was less than that caused by environmentally realistic levels of pollutants (Addison et al., 1985 Edwards et al.: 1988). Liver P-450 activity in this species, therefore. might be used to indicate environniental contamination. However. inducible P-450 activity in American plaice livers was low and did not vary signi'ficantly over a presumed organic pollution gradient in New Brunswick (Addison et al., 1991). The inference was that organic pollution was low anrd uniformly distributed in this estuarine-river system. Si ilarlvy hepatic P-450 IA activity was highly variable in n1 u lvichogs ( P macithi/ns hi~; uc/ ui l,) sampled from salt marshes in Massachusetts, and did not correlate with gradients from relatively clean to highly contaminated (Moore et al., 1995). Nonetheless, liver toxicity is thought to be linked to Cytochroine P-450 activity. High levels of PAfs have been found in Boston Harbor sediments (Malins et al., 1985) and are thought to induce win-ter flounder liver toxicity. Various pathologies seen in liver tissue excised frlom winter flounder collect-ed friom Boston Harbor were attributed to PAI I-induced g1enetic mutations leading to tumor forma-tion (McMahon et al., 1988a.b; Figure 4.1). From the late 1980s to tile present, however, tumor prevalence in winter flounder from Boston Harbor (Deer.Island Flats) has decreased from a high around 12% to 0%, even though PAI-I concentra-tions in the sediments have not changed signifi-cantly (Mitchell et al., 1998). Thus, PAH may not be the causative agent for inducing hepatic tumors in winter flounder. Experimental work implied that the MFO system is involved in tumor formation. Cytochrorne P-450 enzymes (EROD and Al-IlH) were induced in winter flouLnder in the laboratory by injection of the PAH N-naphthoflavone (Stegeman et al., 1987). Immunohistochemical treatment of liver tissue firom winter fIounder fur-ther revealed evidence of liver histopathology (Smolowitz et al., 1989). Winter flounder fed chlor-dane-and benzo(a)pyrene-contaminated food developed proliferative lesions similar to cholan-giocellular carcinomas in winter flounder taken from Deer Island Flats in Boston Harbor (Moore, 1991). These studies show that P-450 could play a role in the production of a mutagenic metabolite irom environmental chemicaIs takel tiP by tile fish. but are not sufficient to identitfv the causal agent. The breakdown products of several PAI Is are often more toxic than the parent Coiiipounds. PAIH metabolites have been detected in adult cod (Davies et al., 1984). In parallel field and tank studies, fish exposed to nominal levels (50 ue/L) of benzo(a I C)pyrene in the wvter showed liver A HH values 5-40 tines that of the control. These inetabolites :an be accumulated by predators vid their prey (McElroy and Sisson, 1989). Risk assessilnlts for predators IIIust therefbore take into account metabolites produced by prey as well as the parent compound. Chlorinated pesticides are known to elicit neu-rological effects on organisns, primarily by inter-fIering with acetylIcholiine/acelylcholinesterase func-tiol. Laiboratory exposuIr of 3-yr old cod to low levels of DDT produced tachycardia (rapid heart-beat), a decrease in the fiequency of respiration, and disruption of the central nervous system's reg-ulation of miLuscle contraction in stomach and gut. Upon removal of the toxicant, however, normal functions returned after 6-7 d (Shparkovskii, 1982). Other modes of toxicity are also possible, although g'enlerally -it high or1 aoch lorie concentrations. For example, chlordane inl high doses induced severe liver damage, and at subacute doses pro-cduced macrophage aggregation and a persistence of necrogenic effects in the liver (Moore, 1991). Hydropic vacuolation, regarded as a precursor of liver neoplasia, appears to be correlated with envi-rolniental levels of chlorinated hydrocarbons (Mitchell et al:, 1998). Cod larvae are far more sensitive to the chlori-nated pesticide DDT and its breakdown product DDE than are the Iiellbrane-protected emibryos. Percentages of malformed and dead emlbryos and larvae increased with increasing concentrations of DDT, which was overall more toxic than DDE (Dethlefsen, 1976). Chlorinated pesticides also exhibit toxicities to winter flounder eggs and adults. Abnornial gastrulation and a high incidence (39%) of vertebral deformities were seen in developing eggs from adult winter flounder experimentally exposed to very low, sublethal concentrations of DDT(I-2 lug!L; Smith and Cole, 1973; Figure 4.1).
53 A-I N&~t N 4 Vt NAN Stir / NA N, 4 N I, ~Ž~' D V 2 ~ NAt >3/4A .*AFA>*?< ~ c< N h'-, A A 'N <S <A/A ~tt~L~ A E A-2 B c( Figure 4. 1. Some examples of abnormalities in winter founder, Pseudopleuronec'tes americcanns, associated with con-taminated environments. Similar abnormalities have been reported for other marine fish species. A. Normal vertebral column (A. I) and fusion and compression of groups of individual vertebrae (A.2) as described in Ziskowski et al. (1987); B. Finrot disease (fin erosion) as described in Ziskowski et al. (1987); C. Abnormal skeletal development in larval flounder as described in Nelson et al. (1991); D. Gill bifurcations associated with contaminated sediments as described in Pereira (1988) and Pereira et al. (1992); E. Red blood cell micronucleii (arrow) as described in Hughes and Herbert (1991); and F. Liver tumors (neoplasia) as described in Murchelano and Wolke (1991).
-54 No such elfects were seen in eggs from flounder similarly exposed to dieldrin, nor were residues of either insecticide detected in the milt of exposed or control male winter flounder. PCBs ToxicitV has been attributed to PCB exposu re in both the. field and the laboratory. Cod having UIlcus syndrome (epidermal lesions thought to be due to an imbalance in corticosteroid metabolism) had significantly higher PCB residue concentra-tions in liver tissue than did cod without'the syn-drome (Stoi;k, 1983). In heavily urbanized areas of Long Island Sound having higher PCBs in the sedi-inents (New HIaven, Hempstead, Norwalk), winter flounder tended to have lower rel)roductive suc-cess, when spawned in the laboratory, than did flounder from less urbanized sites (Nelson et al., I 991). In that same study coin pari ng several differ-ent sites in the Sound', winter flounder embryos firom the New Haven site had the most abnormali-ties and the lowest percent viable hatch. Nelson et al. (1991) also fotund that floun.der with hilh liver concentrations of PCB (Boston) had small larvae. Black et al. (1988) reported that eggs of winter flounder from New Bedford Harbor (MA) were significantly higher in PCB content (39.6 pbtg/g dry wt) than those [roin Fox Island (a relatively clean area in Narragansett Bay, RI), and larvae hatched from these New Bedford eggs were significantly smaller in length and weight. There was a signifi-cant inverse relationship between PCB content of the eggs and length or weight at hatch. PCB concentrations in winter flounder liver sampled froom 3 southern New England areas with differing degrees of PCB and PA\\H contamination (New Bedford Harbor, NBH; Gaspee Point, GP; and Fox Island. Fl) reflected the varying degrees of PCB-contaminated liver, with NBH> GP> Fl. Liver EROD activity was the same at all three sites, but P-450 concentration (measured immunologically with an antibody against vertebrate P-450.1 A l) was significantly higher in the NBI-H fish (Elskus et al., 1989). The data suggest that P-450's catalytic activity (for EROD) is being competitively inhibit-ed at NBH, (even though P-450 levels are elevated) possibly by some congeners of PCB (Gooch et al., 1988; Elskus et al., 1989). In contrast, sexually mature female winter flounder showed lowered EROD activity and immunologically quantitied P-45()0E concentrations, apparently due to a hormonal effect acting primarily to suppress induction of P-450E, the activation catalyst for EROD (F0rlin and Hansson, 1982). Different PCB mixtures produce different effects in marine fish. Feedina Aroclor 1254 to iuvenile cod to produce liver concentrations of ca. 900 pg/g wet wt had variable effects on the Cytochrome P-450 enzyme system. The P-450 enzyme ethoxycoumarin o-de-ethylase (ECOD) was induced 30-fold, but Aroclor 1254 had no effect on ethoxyresorufin o-de-ethylase (EROD) activity. Feeding Aroclor 1016 to juvenile cod induced no increase in P-450 enzyme activity (Hansen et al., 1983). OTHER CONTAMINANTS Recent studies have focused on a group of chemicals, the "-endocrine disruptors", that interfere with fish (and by implication, human) endocrine systems when present at extremely low environ-menital concentrations. In plasma of sexually mature male winter flounder exposed to crude oil, for example, total concentrations of the sex hor-mone androgen (both free and conjugated) were statistically lower than controls (Truscott et al., 1983). During early maturation of the gonads, how-ever, oil exposure had no effect on total plasmatic androgens and estradiol in either female or male flounder. One subset of these endocrine disruptors, the "environmental hormones", include chemicals that may mimic the function of the sex hormones androgen and estrogen. A broad range of chemicals are known to be estrogenic, including several PCB congeners, dieldrin. DDT, phthalates, and alkylphe-nols, as well as synthetic steroids (estradiol, ethynylestradiol, etc.). While their individual estro-genic potencies differ, all are potentially present in sewage discharges. Alarm over these chemicals was raised in the early 1990s when excessively high concentrations of vitellogenin were measured in male rainbow trout caged in the effluent of sewage treatment plants along English rivers (Harries et al., 1996, 1997). Ordinarily, vitel-logenin, a yolk precursor protein, is only produced in the livers of mature female fish, when signaled by estradiol in the blood. Recent studies have
shown that this phhenomenon is not restricted to freshwater fish. Male flounder. Platichih~vs filesus, collected fi om live EngI'llish estuaries and froii the southern North Sea also displayed elevated vitel-logenin levels (L.e et al.. 1999; Allen et al.. 1999). Investigations are now underwvay to look lor envi-ronmental hor'monles in Chesapeake Bay., Long Island Sound and Boston Harbor. MIXED CONTAMJINANTS Fish are never exposed to single contaminants in nature, but to complex mixtures of organic and inorganic substances of varying potency. Comparisons of fish sampled from relatively clean and polluted sites have documented a variely oF adverse impacts, including slower reaction times. skeletal abnormalities, higher prevalences of degenerating hepatic parenchymal cells, and decreases in such biochemical parameters as hepat-ic and pectoral fin ascorbic acid concentrations, hepatic glycogen and lipid levels, plasma glucose concentrations, brain serotonin and norepinephrine concentrations and the concentration ratio of vari-otis free amino acids in muscle tissue (Olofsson and Lindhal, 1979; Despres-Patanjo et al., 1982; Carr et al., 1991). Planktonic stages have been shown to exhibit cytotoxicity and decreased sur-vival rates. mitotic abnor'malities, chromosome damage, slower developmental rates, cell necrosis, and smaller yolk reserves (Perry et al., 1991: Gronlund et al.. 1991: Buckley et al., 1991, Nelson et al., 1991; Longwell et al., 1992). A variety of other toxicological responses have been demon-strated in fish sampled from heavily polluted liar-bors (e.g. Halifax, Tay et al.., 199 1; Salem and Boston, Zdanowicz et al., 1986, Moore et al, 1995, Wall et al.. 1998; New Haven CT, Wolke et al., 1985. Gronlund et al., 1991; various harbors in the Northeast, Johnson et al.. 1992), and fi-om sites adjacent to sewage effluents (Weis et al., 1992). However, it is generally not possible to attribute the adverse effect to a specific contaminant. The additivity of some contaminants was rec-ognized early on for the various PCB, congeners, and led to the development of Toxic Equivalency Factors (TEF) that are specific for fish (Newsted et al., 1995). Additional models are now being devel-oped and tested to deal with the effects of a broader range of contamni nant mixtures in fish (Broderitis et al., 1995; Logan and Wilson, 1995: Pape-Lindstrom and Lydy. 1997). Threshold concentra-tions of additive toxic metal mixtures need not be high to produce toxic effects (e.g. cod exposed to Cn plus ZIi Swedmark and Granmo. 1981). Limited water circulation in Cstuarine and coastal waters would be most likely to produce examples of such toxic effects in young fish that use these ntursery areas. A drawback to the TEF approach is that it only considers additive responses. A number of studies on fish species have demonstrated the importance of antagonistic and synergistic interactions of con-taminants. For example. several lipophilic contami-iants interact synerOistical iv to modulate the levels of two important detoxification components in the liver of English sole (PlIeuronecles i'etulus; Nishimoto et al., 1995). Different metals often compete for the same binding sites within cells. Because of this, metals such as Ca can protect against Cd toxicity, as shown in the mumMichog, Funduluts heleroclitus (Gill and Epple, 1992). The interactions between metals and organic contaminants have received particular attention. Winter flounder exposed to a PCB (24 h, I mg/L) in the presence of added cadmium (200 ug/L), accunmtlated significantly less PCB in their liver and gills than did those dosed with PCB alone (Carr and Neff, 1988). Additional studies have shown that cadmium arid benzo(a)pyrene interact to alter the biotransformation pathways in the liver of the munilnclihogs (van der Hurl et al., 1998). Zinc and phenanthrene interact to effect the toxicity in sheepshead minnows, Cvprinodon variegatus (Moreau et al., 1999). It is therefore clear that much more work needs to be done in order to bet-ter understand the ilipacts of contaminant mixtures on fish populations. THE CBR APPROACit As bioaccumulation iste/n//obr predic'ting impacts? The answer is, in fact, thiree-fiold: 'no', )'es' and 'maybe'. No, it vwill not be useJul for some containinants either now or in the fidure. Yes, it
56 a!)peas to be use id nou;ii .one con-laIninants.... Lid a mae in thei ItInce it wJ/I hl l c', .i so/ l. ha/ /)1/ t/i1 l coa - ta/ tina/tl7S. anctlnt lot)" all otilisttas. -le' ',ti I:\\l.0C~;m. 1997 It is important to point Outt that nuoSt of the studies of toxicological efflects of containinants reported in the literature have related containinant exposure (i.e. concentrations-in the surrounding water) with the toxicological eff'ect. This is typical-ly the approach that has been taken in toxicity test-ing. where lD01s are computed for exposure con-centrations. M cCarty and Mackay (1993) have recently advocated correlating toxicity with the concentration of a contaminant that accumulates in the tissues of an orgaanism rather than the concen-tration of contaminant in the surrounding water. This is referred to as the "Critical Body Residue (013R)" approach to aissessing toxicltv. Sinlce toxic-ity should more directly correlate with the concen-tration of a toxicant at the site of action in the cells or tissues rather tham the exposure concentration, this CBR. approach should allow us to better assess toxicological effects by pinpointing a potential causative agent among a suite of multiple exposed contaminants, and should allow us to predict sub-lethal toxicity from existing bioburden monitoring data. To support this CBR approach, existing pub-lished data have been reexamined to identify those instances where body burdens were measured along with toxicological responses (Jarvinen and Ankley, 1998). For example, cod fr'om the Baltic Sea that were found to have elevated levels of cad-mium in liver and kidney tissue also had externally visible skeletal deformities (coinpressiols of the spine and deformities of the jaw; Lang and Dethlefsen, 1987; e.g. Figure 4. I). For the com-inercially important Northeast species, less than 30 such studies have been identified (Table 4.3). While a direct relationship between contaminant body burdens and the degree ofltoxicity would be expected, establishing this relationship is often elu-sive, particularly when studies were not specifically designed as CBR investigations: As described previously, both Cd and Hg induced adverse effects in long-term laboratory studies on winter flounder (Calabrese et al., 1975, 1977). Hg was readily accumulated in blood and gill tissues ill a Close-dependent manner, yet there was no statistically signiticant accui'nul tioil of( d under the experi-mental conditions employed. Ihe CBR approach has only been directly tested for fish in a few labo-ratory studies (e.g. Niimi and Kissoon, 1994). Nevertheless, it is clear that this approach holds much promise Imr assessing the potential of adverse responses to pollutants in field collected fish. Additional work will furlher refine and validate the approach in the years to come. POLLUTION-IANKEI) [ISTOPATIIOLOGY AND .lhhcic, p*)lihitio/ has b'en implicaled in the high prevalence of lesions in eastern ,Norlh AtIlantic hollom fish, Conclusive Clause andd cf2fc'l 1clal ionsh/is /r1cnain toj be established. -R.A. stwJrehelano, L. Despres-Paltanjo 01d0. Ziskowski. 1986 Fish that are collected from contaminated sites often exhibit a broad range of histopathologies and L" / diseases, in addition to the lesions and morphologi-cal effects mentioned earlier. Four examples are presented below, as well as a discussion of the interactions between parasites and pollution effects. Investigators have often pointed out the apparent correlation between pollution and these adverse effects, although causation has only been suggested. In only a few cases have laboratory studies been done to investigate possible causative factors. A variety of liver pathologies have been identi-fied in cod, yellowtail and winter flounder collect-ed from the field (Despres-Patanjo et al., 1982; Freeman et al., 198 Ia, b, 1983; Murchelano et al., 1986; Murchelano and Wolke. 1991; Turgeon and O'Connor, 1991). Of 100 live cod collected from Halifax Harbor, 73 had histopathological lesions in their livers (Freeman et al., 1983). Histopathological analysis of livers from winter flounder revealed one liver neoplasm in a fish friom the western end of Long Island Sound and none in fish from the eastern end of that west-to-east pollution gradient (Turgeon and O'Connor, 1991). High prevalences
HIOIMŽTi-AN I 1F: F of liver lesions, blood cell abnormalities, liver DNA damage, liver neoplasms, concentrations of organic chemicals and. trace. metals., and high le\\Cls of PCBs in gonads in winter flounder from New -laven have been found (GreitL and \\Veizloffl 197 Greig and Sennefelder. 1987: Gronlund et al., 1991). 1'Fattv change." a degenerative process in the liver, has been attributed to exposure to organic contaminants or trace metals (Freeman et al., 198 1 ab). Considered with other pathological sig-nals, exceptional accumulation of liver lipid and increases in liver size have been linked to body burdens of PCB, pesticides, and other organic toxi-cants (Sherwood, 1982; Freeman et al., 1983'). Pathological changes in liver seem to become pro-gir.ssihcv), greater with inicreasi ng size 0f t[ie fish (Freeman et al.,, 1983; Murchelaimo and \\Volke. 1991). In a Boston Harbor field study, for example. tumors were not found in Fish smaller than 32 cm in length (Murchelano and Wolke. 1991). The same study revealed a pattern in liver pataoloy: pro-gression from necrotic lesions to neoplasia (Figure
- 4. 1), and suggested pollutants as the likely inducers of the lesions (Murchelano and Wolke 199 ).
Investigators have attempted to induce liver tumors in the laboratory. but with limited success. Payne and Fancey ( 1989) reported that liker hyper-trophy in winter flounder increased with increasing oil exposure for 4 months to varying concentrations of crude oil in sediments although the number of melanomacrophage centers in livers was reduced. Boston Harbor sediment extract, injected peri-toneally, was acutely toxic to Winter flounder; perivascular edema was observed after 10 d in stir-vivors (Moore, 1991). Gardner and Yevich (1988) reported that fish exposed for 90-120 d to sediment fi'om Black Rock Harbor (Bridgeport CT) devel-oped neoplastic or proliferative lesions in the kid-ney, olfactory and lateral line sensory tissues, gas-tro-intestinal tract, and buccal (cheek) epithelium but not in the liver; cytopathology and cell necrosis were also detected in the pituitary. In the field, win-ter flounder collected from Black Rock Harbor and New Bedford Harbor (MA) had similar lesions. A second well-studied example of histopatho-logical impact is the increase in the incidence of small inclusions (micronuclei, MN) in fish red blood cells (Figure 4.1). MN were elevated sixfold in flounder from the New York Bight Apex as com-pared to fish friom the inshore Gulf of Maine and Block Island Sound, and twice those iound iii Georoes Bank and Long Island Sound flounder (I-InOlies and I lebert, 9 1.). Inshore New Jersey and Viirginia fish had significantly higher MN fre-Iucies than thosne !rn, the GullFof Maine and Block Island Sound. Ihere were higher frequencies of MN in flounder ftiom Hempstead and Shoreham. N.Y. as compared to most other sites in the Sound. Erythrocyte MN were consisteltly higher (Hughes and Hebert. 199 1 ) in flounder from Ihe more highly contaminated stations examined, New York Bight Apex and Hempstead, which are contaminated with metals arid PAH (Carmody et al., 1973; MacLeod et al., 1981 ; U.S. EPA. 1984). Winter flounder col-lected from the coastal mid-Atlantic had statistically higher evcryiiocvyc nautation feclucncies than those froom more offshore waters (Longwell et al.. 1983). Winter and wvindowpane flounder from western Long Island Sound had significantly higher fre-quencies of micronticlei than those firom the New York Bight, wiith ilh froin both these areas having signiticantly higher mutation firequencies than flounder sampled elsewhere (Longwell et al., 1983). The higher incidences suggest a link with environmental pollution. Several diseases also appear to correlate with pollution. A high incidence of fiu-rot disease was observed in windowpane, winter, and yellowtail flounders exposed to materials Cdlimped in the New York Bight (O'Connor, 1976; e.g. Figure 4. 1), win-ter flounder having the highest incidence. The highest rate of fin-rot in yellowtail and winter flounder was seen in fish collected from the inner New York Bight when compared to either offshore waters of the outer New York Bight or inshore within Massachusetts Bay (Ziskowski et al., 1987). PCB concentrations in muscle, liver and brain tis-sues were higher in winter flounder with. fin-rot frorn contamiinated sites (primarily winter flounder) than in fish from reference sites (Sherwood, 1982). The erosion pattern of the fins arid the association of higher prevalences of fin erosion with greater degrees of sediment contamination suggest that fin-sediment contact in an area where toxic contami-nants have accumulated on the bottom is an impor-tant factor in development of the disease. Lymphocytosis (elevated mean blood lympho-cyte counts) is a second example of a potentially pollution-related disease. High lymphocyte counts in winter flounder were correlated with liver
5 1 8 '[ I-t i i I necrosis and suspected levels ofsediment chemical contamination; winter flounder collected f'rom Boston HI arbor had higher nLutimbers of in mature erythrocytes than 'did those fiom less urbanized envirotnments (Daniels and Gardner, 1989). Disturbances in the distribution of blood cells and alterations in lymphocyte counts were related to neoplastic lesions and indicative of chemical con-tarnination in sediments. The interactions between fish parasites and coontaminant impacts are complex. On the one hand, parasitic infections may make fish more prone to the additional stress caused by pollution. In a laboratory exposure., hemoprotozoan-infected cod reacted more sensitively to petroleum hydro-carbons than did non-infected fish (Khan, 1987), as measured by poor body condition, excessive nItic us secretion by the aills, retarded gonadal develop-ment, and greater mortality. Similarly, juvenile and adult winter flounder, some infected with the blood parasite 7iJvuaiwnsoina inu*inta*ensis., were exposed to sediment contaminated with crude oil (6 wk, 2.6-3.2 rng/g) or to clean sediment (Khan, 1987).. Mortality was significantly higher (89% for.uve-niles, 49% for adults) in infected, oil-exposed fish than in fish with either condition alone. On the other hand, the stress caused by pollution may make fish more susceptible to parasitic infection. In the field, parasitic infections accompanied by low-ered host resistance were found to be more preva-lent in cod after chronic exposure to petroleuin hydrocarbons (Khan, 1990). Likewise, exposure to oil in the laboratory, increased the incidence of Thypanosoma infection and death (Khan, 1987, 1991). Interestingly, parasites may in some cases be more susceptible to pollutants than the fish host. As a result, fewer parasites might be fouind in fish exposed to contaminants. For example, Khan and Kiceniuk (1983) observed that there are fewer par-asites in fish exposed to oil, and suggested that the lowered parasitism might be attributed to toxicity induced by water-soluble fractions of crude oil and/or modification of the gut environment. The intensity and prevalence of parasitic infections were more pronounced in fish exposed to water-soluble extracts than in those exposed to oil-con-taminated sediment (Kahn and Kiceniuk, 1983). POIui.rI.AIO l() I: EI IK-CTS As described above. there is ample evidence to show that commercially important species bioaccu-mu ulate~contam i nants and exhibit toxicological responses to contaminants that they are exposed to. These effects are generally restricted to heavily polluted coastal sites. Although the impacts on ld i vidual fsh may: be of interest to toxicologists, it is the possible adverse impacts on fish populations that are of interest to fisheries managers and envi-ronmental regulators. Assessing the impact of con-taininants at the population level of biological orga-nization has proven to be difficult, but is currently one of the most active areas of toxicological research. Two aventIes are beil*g pursin d: () rising biomarkers: and (2) incorporating contaminant impacts into currently used population dynamic models. Biomarkers are biochemical, cellular, physio-logical or behavioral changes that can be measured in tissues and provide evidence of contaminant exposure and/or toxicological effects (Depledge et al., 1995). Investigators have attempted to correlate one or more bioinarkers with adverse impacts on tish populations (,Johnson et al., 1992: Stein et al.;. 1992; Wall et al.. 1998). For example, the induction and expression of Cytochriome P-450 enzymes have been proposed as biomnarkers of organic con-tam inant exposure (Stein et al., 1992; Moore et al.. 1995). However, in some highly polluted environ-ments (e.g. New Bedford Harbor). EROD activity in winter flounder was depressed even though P-450 gene induction was evident (Elskus et al., 1989). In another polluted locale (Newark Bay), both adult and larval mummichogs failed to exhibit P-450 induction at all, sriggesting adaptation to pol-lution stress (Elskus et al., 1999). These examples demonstrate that biomarkers must be asssessed carefully, and the use of a single biomarker is unwise. Biomarkers cannot, at present, be used to predict impacts on future population structure. Investigators have also attempted to incorpo-rate toxicity data into fisheries models. Initially, modelers simply modified the mortality term in population or recruitment models to include a com-ponent which they attributed to contaminant toxici-ty (Waller et al., 1971; Wallis, 1975). However. these authors provided no rigororis jistification for their contaminant-induced mortality terms. Another
'(ILTIANT59 approach applied multiple linear relression to fish stock data to assess the signiific.ance of hvdrological factors and contaminant impacts (e.g. sewage load-In I seag load ing, dissolved oxygen concentrations, biological oxygen deniand) on the historical time series data (Summers and Rose. 1987). This modeling indicat-ed that hydrological factors were far more impor-tant than contaminant effects for striped bass stocks in the Potomac, Delaware and [ludson Rivers, whereas pollution was of more significance for American shad. While this approach can explain historical data, it is not useful for forecasting (Summers and Rose, 1987). A third approach con-bined toxicological data with physical occano-graphic data in a risk-assessment model (Spailding et al., 1 983. 1985) in order to assess the probable eftects of an oil spill on cod populations. This assessment provided useful predictions: (1) most of the hydrocarbon impact on cod would occur within the first 60 d after a spill; (2) 41.5% of the spawvned cod would be adversely aflected by oil concentrations in excess of 50 ltg/L; (3) cumulative loss to the population would peak at 23.9% in the 7th year a fter the spill: and (4) of the four seasons. winter and spring spills would have the greatest impact. Recently, investigators at Oak Ridge National Laboratory have further advanced the methodology needed to incorporate toxicity data into fisheries models. Two of the most critical steps in this pro-cess are the application of acute toxicity test data (e.g. 96 h LC, 0 data) to predict thresholds for chronic lethal and sublethal effects, and the extrap-olation of data from one tested species to another (Suter et al., 1987; Suter and Rosen, 1988; Barnthouse et al., 1987, 1989). Not only survival, but also sublethal effects, including reductions in fecundity, can then be calculated (along with confi-dence limits) and applied to fisheries models. Initial work indicated that fecundity is the most sensitive toxicological factor that needs to be incor-porated into population models, and has a greater long-term impact than reductions in survival of young-of-the-year fish (Stiter et al., 1987; Barnthouse et al., 1989). Barnthotise et al. (1990) then predicted long-term changes in Gulf of Mexico menhaden and Chesapeake Bay striped bass populations using a Leslie.Matrix-type life cycle model. They included natural, contaminant and fishing-induced age-specific mortality, as well as age-specilic fecundity in their analysis. Because of differences in life histori, menhaden and striped bass had different capacities to sustain the same level of containiant-indUced mortality. Menhaden were better able to tolerate pollution. The model also showed that fish populations that have been reduced in numbers by overfishing were much more susceptible to the increased mortalitv and reduced fecundity caused by contaminants. Current models used by fisheries scientists to predict long-term effects of exploitation on fish populations are quite imprecise. Adding in the effects of contaminants., with its own order-of-mag-nitude confidence in the extrapolation from acute toxicity test data adds another layer of uncertainty. Barnthouse et al. ( 1990). for example, cautioned that the tmcertainty in estimating Iong-term effects on fish.populations using their model was generallV greater than the range of responses to contami-nants, since the largest source of this uncertainty is attributed to the inherent uncertai ntv of curre lTyIN used fisheries models. Nevertheless, modeling is already providing considerable insights as to the interactions between contaminants and overfishing on various fish poptilations. With further rofine-ments, more holistic models should be able to examine a Multitude of forcing factors, incliding fishing pressure, habitat alteration, contaminant effects and natural environmental variability. SNIxMMAiln' AND DISCuSSION The highest concentrations of chemical con-taminants are to be found in coastal, industrialized or heavily urbanized, and waste-disposal areas. Such estuarine, coastal habitats are also the spawn-ing and nursery areas for many important comlmner-cial fishes. These early life stages are most stiscep-tible to toxicants, the larvae more so than the eggs, as the latter have the protection of a membrane (Dethlefsen, 1976; Mangor-Jensen and Fyhn, 1985; Foyn and Serigstad, 1988). In some fish species, tissue concentrations of pollutants do not necessarily reflect sediment con-centrations of those pollutants, whether metals or organics (Greig and Wenzloff, 1977; Greig et al., 1983; MacDonald, 1991 ). The work of Marthinsen et al. (1991) illustrates the difference in this respect between fish species: they found that PCB levels in Atlantic cod reflected a decreasing PCB pollutant
60 gradtient h-o01 the tcmn outh of Norway's larget river, whereas PCB levels in tile European flounder did not. In wintCr fltonder. PCB body burdens were accumulated from prey species in the sediments,. rather tha horom tb water column or flont sedi-ment contact (Connolly, 1991). Circumsiantial evidence linking disease and abnormalities in various fish species to polluted habitats is abundant. Proliferative lesions in endocrine, exocrine, respiratory, sensory. excretory and digestive organs, alteration of plasma protein and ion concentrations, and interferences in metabolic pathways were found to be characteristic of species such as winter flounder that spend much of their lives in some moderate to highly contarni-nated inshore areas. Liver disease was found to be absent in populations frorn uncontaminated off-shore areas. 'fihe degree of sediment-chemical con-tamination and disease suggest a causal interrela-tionship (Gardner et al.- 1989). More immediately associated with p0lthiant exposure, abnormally high levels of detoxifying P-450 enzymes may signal (for a short time) expo-sure to organic contaminants such as PAlIs, PCBs and chlorinated pesticides (Addison and Edwards. 1988). This response varies with sex and gonadal maturation (Spies et al., 1988a, b; George, 1989). Similarly, induction of metal-binding proteins may signal (tor a short time) exposure to heavy metals (Fowler and Gould, 1988; George, 1989; Roesijadi and Robinson, 1995). Unlike PAHs and chlorinated pesticides; differ-ent IPCB congeners sometimes elicit conflicting effects (Hansen et al., 1983), with some congeners inhibiting others (Gooch et al., 1988). A hormonal suppression by one PCB congener of the detoxica-tion of another PCB. for example, has been observed in sexually mature female winter flounder (Forlin and 1Hansson, 1982). Black et al. (1988) found a significant inverse relationship between PCB content of eggs and length and weight of lar-vae at hatch. Goksoyr et al. (1991) have shown that in the early life stages of a fish, the normal protec-tive production of enzymes that break down organ-ic toxicants for elimination is delayed until after hatching. Tissue concentrations of organic contaminants such as PAHs, PCBs, and pesticides are significant-ly correlated with body-fat content (Reid et al., 1982); PCB body burdens vary with season in lfemiale but not inl male fish (Marthinsen et al.,. 1991 ). The fattier the liver, the slower the clearance rates of these fat-soluble toxicants (Skgire et al.. 1985). Induction of Cvtoch om.e P-450 enzymes is associated with liver pathology in fish, a circum-stance that could play a role in the production of cancer-producing agents from environmental chem-icals by generating breakdown products more toxic than the parent compound (Sinolowitz et al., 1989). Ulcer-like lesions are considered to be a result of hormonal imbalance caused by PCB assimilation (Stork, 1983). Chronic exposure of adult cod to crude oils produces severely disabling lesions and reproductive impairment (Khan and Kiceniuk, 1984; Kiceni ik and Khan, 1987). In the case of metal-organic interactions, cad-n mium strongly depresses several detoxifting enzyme systems (George, 1989), and appears to depress PCB uptake in winter flounder (Carr and
- Nefi, 1988). In contrast, the European flounder,,
Platichth-Vsflesus, when exposed to diesel oil showed no increase in detoxifying activity" when copper was. added to the oil (Addison and Edwards, 1988). Overloads in marine animals of even essen-tial trace metals (notably copper) can interfere with normal intracellular metal regulation, with conse-quently lower fish health and often reproductive failure. These phenomena have been observed most clearly in a Gulf of Maine marine bivalve, the sea scallop (Gould et al., 1988; Fowler and Gould, 1988). From the foregoing review, it is clear that pol-lutants can alter the normal health and physiology of Northeast fishes. When these fish are exposed to pollutants in the laboratory. a variety of adverse effects have been clearly demonstrated. When fish are collected from contaminated environments, pol-lutants are measured in the tissues of these fish and associated harmful physiological and biochem-ical effects can be observed (Table 4.3). The exact contaminant responsible for the effect is often elu-sive (Wolfe et al., 1982) because multiple pollu-tants are usually found in a contaminanted environ-ment and the pollutant effect may be due to the combined action (additive, synergistic or antagonis-tic) of a mixture of pollutants. The major factor that remains unclear is the link between these observations and the effect that pollutants might have on the population structure
"MA, I ii/X lýHC 'ia 6 of the varioUS fish stocks. O)ur flailuri to make rea-sonable quantitative estimates of these effects at the population level may be a result of our inaIbility to separate clearly effects of pollutant stress from other encVironeinettal stresses. Overl.shin', c limate changLes, food availability, habitat alteration, and predation are amnonf the other factoi's that after fish population levels an o nbscure any possible effects of a degraded habitat (Cohen et al.. 199 1 Sindermann. 1994). Sindermann (1994) perhaps best sums up the present state of' this dilemma: It seenis. withi the evidence /7rCeseiiilY cn tw(t/a~/alc:, 1/h/~.1o'chIu/ 0117,1" 7 I/hi /)O[tl-1ion ure ovetridiing iii delter-'niini*ugi/s a ac/oce. bit/ uie hick sq/liciewi qualiii-(olive dalo to iuake I)ositive sltaemensl /2o0/I cause and e*ltela rettionsthp.s, of clffclac/t a /cii /)o11/1110iion. -CJ Si'ndcrnanim, 1994 Ile further suggests that implementation of new poll uition mon intort ng and assessment programiis, critical findings from laboratory and field studies, better and longer-term data sets, as well as the development of new simulation models, may pro-. vide answers to this vexing problem of listiinguish-ing pollution effects from. overfishing, habitat degradation and other environmental factors, and allow us to assign a quantitative estimate of the impacts of pollutants upon fish stocks. LIfERATURE. CITEI) Addison, R.I. and AJ. Edwards. 1988. Hlepatic microsomal mono-oxy..einase activits in llounder Plhiilcht'.s /lesus fron polluited sites i I.angesunId ord and romrn mesocosms experimentally dosed with diesel oil and copper Mar. Ecol Prog. Ser 406: 51-54 Addison, R.IF,- A. Idwards and K. Renton. 1985. lepa/ic mixed func-tion oxidascs in winter tlounder (l'seutioplettiout*c es aoiericanus): Seasonal variation and response to PCB fceding. Mar Environ. Res. 17: i50-151. Addison. RT., PD. Hansen and E.C. Wright. 1991. Hepatic Mono-oxygenase Activities in American Plaice (lippo"/ossoi/s plates-soides) from the Miramichi Esiuar\\'. N.B. Can. "ech. Rep. Fish. Aquat Sci.. No. 1800. 18 pp; Allen, Y., ATP. Scott, P. Matthiesen, S. iIla,,orth. J.E. Thain and S. Feist. 1999. Survey of estrogenic activity in United Kingdom estuarine and coastal waters and its efldets on gonadal develop-ment of the Ilouider PlauicithysJlesus. Environ. Toxicol. Chem. 18: 1791-1800. Iant/Ithousc. I _W (iV W. xtr ti. A I.. I sc n and... / uc I atIp, 19 is7. tint vesonscs . t"stI ppais t ic 'on/int-o ~ ~ ~ ~ ~ 1 to/ IOI isirn MCIco hn lll.i nants, F, nviron, A"l,\\xieo I Che 6 S8II-824 BalnitOse. L.W.. G.\\. Su'ic II id nAI Rosen. 19S9. lltn u tirin pop-ulation-lt vel signifiicance fiott indi idual-level el/cc/s At-n cxtrapnlati n iroin fitshee science to /xceolo lit Aouatic -iixicolo', and itot',it H il I.e VAl. I. I. ILcooitsd (3iW" Suter it eds. Si'P 1007 Aimirican S ciet,' for -lestni tc and Materials, Philadelphia PA Ppo 289-31)6 Bartthouse. L.W.. GW. SUtcr II and A'. Rosen. 1990. Risks of toxic Con]taminant]s l[e'po iid Ii polpulaijtwlsý h{ el c o:, [iJ'e his-tory' data uclertaints aid exploitation intensity. tviron. iToxicol Checot. 9: 29 '71 I Black, D.E., D.K. Phelps and R.L. apan. 1988. rTe effect oi' inherit-ed contamination oni egg and larval Winter flounder. 'si pl;'*,tii tio cl nittyiric auto. aNI . il.'viron. /iRes 25 45-62. Bodammet. J.E 198 I. "lie Cytopathological Effects of Copper on the 1Ofactors Organs of Larval Fishi (! seudoti)leuonecies ariericcinus anid He 1a;ttg'ixtntinusii egllJfiu ittist IC ES CM -19 SllE 4 6 ( Biol.) Bohle, B. 1983, Avoidance o1f petroleum hidrocarbons by the cod i(,o'adhi 'situ Irisu, Dirý Ski
- 10.
r Kv, .ldcui. I ? IIodterius SJ.I NI.I) Kahi and M.I. Itoclund, 0995. Use of ioiit toxic response Lo define tile primary iode oftoxic action fbr diverse itducs/tritl or"'ani che iciv sx Ini/irr "foxi ol Chctiy 14: !5;91-1605. BLIckley, L..I. A.S. Smigielski T1A IlIalavik E MI Caldaronei BR. Bucri/s and GCC ILaurctnc 19901, Winter fl*oind er i'.~c'tt~f jici'he,, i ti.* i.Cv'i Co
- i.
. A. nolln - location variabtlity in size and survival of larvae reared in the-laboratory. Mar Icol Pro-S-i. 74: 117-124, BuIcroto i ., M. 1. I crtct itd 0 K cIdlei. 1984. ipidermal condition ii post-spawned winter foliuicc, Ps-eu'dop/iettsonieces ameri/t 'anits fWaldbacirn), mai/aincd in helai /Hd i Der exposure to crude ptiolctmi JI Fish Bic/i 25 503-606 Calabrese, A., F.I. A Iicrherg. 'viA i,)Dawson and I) R. Wenzto'f 1975. Sublethal phi siol giai-stress illduceyd.b1 cadvnium mid inercusr' in tie wintei flounder, Pset'iioplettro, cices antericamii, In: Sublethal Effects of' loxic Chemicals on Aquatic Animals.111 Koetnan and J.J.' \\V.A. Strnk eds ). isevier Scientific Publishing House Amstvrdam. Pp 15-2 1
- aliihresc, A., F.P TIhurbcrvg and F Giouldc i97 7,i F/ic/s if cadMicum, mercury and silver n/in marine animals. Nar. Fish. Res 3)9: 5-Il.
Carson. R. 1962, Silent Sin. Houghtan Mi/lini Publ., Ioston/i. MA 368 pp Capctzzo, J.M.. A. Mvcmiroy and G. Wallace. 1)87. Fish and Shellfish Contamination ii New England Waters: an Evaluation and Review of Available Data on the Distribution of Chemical Contaminants. Report to Ccoast Alliance, Washington D.C 59 pp. plus appendices. Carmody, D.J., I.B. Pearce and WE. Yasso. 1973. Trace metals in sediments of New York Bight. Mar. Poll. Bull. 4: 132-1 I35. Cari-. R.S., KI'. Hilhman and J M. Neff. 1901. Field assessment of biomarkers tor winter tocunder. Mar. Poll BuOc1 22 61-67 Carr, RS. and I.M. Neff 1988. lInhienye oflprior exposure to xenohi-oties on the metabolism and distribution o' poychloriated biplienyls and phenantihrene in winter flouinder, l'seudlopleurotectes americoiust Mar.I Fnviron. Res. 24i 73-78. Chan, K.M.. W.S. Davidson, C.L. I tew & G(L. Fltcher. 1989. Molecular cloning of metallothioneiti ctDNA and analysis of rnet-allothionein gene expression ii wintei flounder /issues. Can. J Zool. 67: 2520-2527. Chapman, INPI. 1997. Is bioaccuImulation useful for predicting i/pacts? Mar. Poll. Bull. 34: 282-283. Cohen, E., D.G. Mouitain aid R. O'Boyle. 1991. lcocal-scale verscus large-scale factors affecting recruit/tent. Can. J. Fish. Aquat. Sci 48: 1003-1006. Connolly, J.T. 1991. Application of a food chain model to polychlori-
itacd hilliclyl[ cotilao inatiol o t" [lie iob-ter nd*il mwr ic loinctel ficod clhiams in Nesw Bedibrd Harbor. I-nviron. Sei Terlinl 25: 760-770.* DaLiels-T.G. and G.R, Gai doCr. 1989. A coIlpaiaiivc sttdV o the dll-ferential blood cell counts of winter I ounder ('seydosiel it/inec'es oii riitnic) collected in News England. Malr lFii5 roill e.,. 2,58: 5-1 I a venport. I . S. I,oniing a;nd I.J. Sacthre. 1979. T1he et cicts i 1 F'kofisk oil extract upon oxygen Uptake in eggs and larvae ol the cod. Gadus miorhiui L. Astarie. 12: 31 -'4. Oi~ases...M...1. lullin. i C I 1h J, A-5\\ I.p isol r thes levels of hepatic arvI hydrocarbon hydroxyl ase in iIh catight chisc to0 and di-iUnit hr!el North Sen oil licUds NIi Eviron h, 14: 23-45. Dawson, M.A. 1990. Blood chemistry of the window, pane fliounder Scophalihnus aquosts in I.o0n.Islanad 'SoLind eograFlhical sei-sonal and experimental variations. Fish. Bull. 88 429-437. Depledgc. MH.. !A. Aagaard and P. Gyorkos. 1995.-Assessment of trlace octal IOxiCitv LiSiiig iiioiccUlar, phlsiological und bchavioral bioinarkers. Mar. Poltu Bull. 31. 19-27. Dcsmre.-'iiinc I., I -.1 Ziviowsvl and 1,>.\\ Nlirlxc!ain,,, F0 2. Distribtiiioii of lishll Disecaces Monitored on Stock Assessmenl Cruises ill the WCestern North Atlantic. ICi:S 3M-l9823( l M"I i.)). Oethlefsen, V. 1976. The inlluence of DD'I and DDE oil the enibryo-geneisis and the mortality of larvae of cod (Gadus moirhua L.) Mccrl'orschung. 25: 115-148 IChleh :rcu, V )1.9,6 Fibh h1 the pollillte North Sea tcntm. S: i09-I_ De-, A C.- IW. Kiceniuk. 11 P Williami. R. I'.A. Khan and J.F. aI' lie 1983. Long-term exposure of marine fish to urnde pctrolcunt I. Studies on iliver Iiplids aidi i Iy aclt S ids hI cod (1fIndiS iii0,1iiii) aii, wvinter flouinder /icileiCHIeiiliiaS). CoI. Biocheln. Phsvo 7-.' 93-!l1. Eidwxards. A..I., R.F. Addison. i.E. \\Villis and K.W Rentcni 1988. SeCWonIIl Vuriýt on of hcp-at ic mixed Frinction oxidascs hi xvin tLer fPoundeer (l'seldoplem'onectes ameirici-itls) Mar. lFx'viron. tes 26: 299-3 09. Elilrlich, P.R. and A. IH. Ehrlieh. 1970. Population Resources Enivi ronmenlt Issuts inl I-Hutilait Ecol ogy W. I1. I-reenaill, Sait Francisco, CA. 383 pp. FIiskus. A. A ...- Stegeman. I_-.F - SLtisan i, 1). Black, R... IPruell and S... Fluck. 1989. Polychloriated biphcnys-colncenltration ýlnld (Cviochrome 1l-4501. - expressiOn ill wVllltei tlrinder frot coqllii-- nated environments Mar. l-.nviron Res. 28: 25-8 Elskus, A.A.. JJ. Stegeintan, JW. Gooch, D.E. Black and R.J. Prell 1994. lolyvhlorinated biphenyl congener distributions it winter flounider as related to gender. spawning site and congener metabolism. Environ. Sci. Technol. 28:. 407. Elskus, A.A., E. NlotOsson. A.F. MclhEloy, JEl Steceutian and ).S. Wolhering. 1999 Altered CYPIA expression in /-indiliis helelro-c/itis adtlts and larvae: A sign of pollutant resistance7 A stt Tox_ 45: 99-113. Farmanlhrnxaiaml, A., M. Fisenberg., R Socci. V. lannaccone and R. Hsia. 1981. Interaction or mercury compounds With Ictiucte trans-port mi the intestine of winter and summner flounder Bliol. BtuIlI 161: 325. F6rlint. L. and '. I laitsson. 1982. Effects of oestiadiol-I 7b and hVpophysectorn-y on hepatic mixed function oxidases i rtinbow trout..I En.o. r 95 245-252. Foureinan. G...- N.B. White Ih. and I.R Bend. 1983. Biochemical evidence that winter I ounder (tPseudopleu-onec-es amiericanus) have induced hepatic Cytochroite P-450 dependent monooxyge-nase activities. Can..I. Fish. Aquat. Sci. 40: 854-865. Fowler, B.A. and F. Gould. 1988. Ultrastiuctural and biochemical studies of intracellular metal-binding patterns in kidney tubtile cells of the scallop Placopecien nitael/uaicus l-6llowinxg pro-oneud -xposoii -o ci niinult ri o.r -o r. NIar ll. 97, H I"tvni, LI. and 1 Serigssad. 19,". Oil I.x lortiort in N, e',t: ()ihohre Fields Fish ILarvae as the Critical omiponelt in tie Asscsslit 01 Potculial tonsetluenCes IIr thie ish RCSItuihcS. IC28 (N'I-19885/E:! Frceinaii. I.C. B B.tungilaio ( n}irl' c NIand NI M NCInenix. 1(1 l81a. Tiuc ill ro 17i liol-Ls l' Iictl i v - i-c lh\\tri, )phthalaei lDehpi i n the Atla-tvc Cod ir(ridies tiirhita) tCl S C-1981/ liE:5 Fleeimant: IC-I.F. l UIthe. G Il1. Sanualani and I.TI Garsidc 198 1b. Contaonlnant'liver I listopathology in Canadian Atlantic Cod 1(i-LHv-,,i u I IU S C 'M -1iS ii l! F~recman. II.C 13, San alann J.I.. ithel FT1 (;arside and PGi
- tta,:
x 1 N,\\ i~is,l,,ivtu ealmihin iu lk ai';icd a a!.-us, lr sus p chlorinated lhdrocarhon lit. inshore Atlantic cod (l,6alicis lm/oniu). Arch. tI viron Contain. Toxicol 12: 627-632 I-iceli'it). II.C. and.I. Uthe. 1984. iPolychiornated bip eliiyls, organochlorine pesticides and chlorobenzenes content of livers from Atlanhtic cod (Gthcis morhmuna) catught off -lalithx Environ. Ilouilitoini 1-4 Assc ss. 4:389-3941 Gardner, GR.. R.J. Prucll and L.C. Folnar. 1989. A comparison of both n*i-iasiic aiid ut-o-i-nopt:sic disoiders hi, i-tci Pounder S/'.'&'ihlld ~/e, iliili*{'.'ues o {lli'm icTiius) I'rot'ii eimihil Icas, in Ne\\, uul'uiuland Nlar I.viriui Ices 28,393-3')7 Galciuter. (".1R. lurd P.1) Ycvich. 1 988. CouniParative histopaitho,.gical eltLe is of chemitcally cottaitinated sediment oni marine oran-iss. NMar Environ. Res 24: 311-316. George, S.G 1989. Cairn ilm efthcits on plaice liver hebobiotic and Ictll[i dcui\\.vati-t n -.teCiiL:t; Iicse-respciise AC.*ulat 'l \\-vo I -. 303-3 1IH, Glcrhart, I 1, 1977, Pes-icicides in fish. wvildit iand estuaies-Pestic.
- Monii..I. IH: 132-133.
Oilt. T.S and A tIpile. 19)912. ilipi at cfiCadinituli ona the iniLiMttillichog' ,i ii, ii-h it'/ and the Ile oI e alci itcuin lit tI csst heavy ItL'-!! tox-city Ioun lpr ileulCn( PlisMi I0lC: 519-i23, Gioksovr, A.. iB. S-riuxuad. I.S. Solber and.I.J. Stcszeitiaiin. i9S'S Response o" -cod ((,C'iIuI lilol/iticl) larVa-e ldi.jutvenICs to O exposure detected with anti-cud 12tochrome lP-45Oc IlG and anli-scup P-450El; NAab I -.12-3 Mar. Ennviron. Res. 24:31-35 (ioksoyr, A., TS.. Soilbihg and JI, Serigstal. 1 99 1. Ihlint tuno.henlical detection o'civtochromc 1-4501AI induciirht in cod larvae and LIVcnilcs e\\xposeCl i a weater-soltIuble faicliolt of North Sea crlde oil. Mar. Polil. hu _L 22: 1-2-j27. Gooch,.. W -VA. Flskus, P.. Kloeppcr-Sauis, M.-. HI ahn and.1-1i Sien nL;c l I tit Ifl'ects oL ' tltri-tandix u tu l trho-suibstittiled poly-chlorinated biphenyl coilgencis on the hepatic i*tOitooxygenase sysieM ilt seLip (l lt'JOIOIOis -ichrysops). Toxicol Applied Pharlilac. 98: 422-433. Gould, E. 1977. Alteration to'enzytics it Winter Ilounider, /'selldoi/)elfr'oiitces (intel.ctiniOýS* exposed to sublethal amounts of cadMinulln chloride. In. Plhsitlogcical Responses of 'Marine Biota to Poluitants. F.J. Vernbetr. A. Calaitrese. I.P. Thurberg and W.tB. Veriberg (eds ) Academic press, Ne'wx York, NY. Pp. 209-224. Gould, F., R.J Ihompson, I.J. 1iuckleys D. RUsanowsky and G.R Senrellider. 1988. UJptake and eIfects of copper and cadmium in the nonad ofilthe scallop Placopecleni mncgeolanicus: CoxLcurrelit nmetl exposure. Mar. Biol. 97: 217-233. Greig, PA., S. Schurman,.J. Pereira and P Naples. 1983. Metals and PCB concentrations in wxincdowpaixe flotunder fronx Long Island Sound Bull. E1n\\,iron. Contain. Toxicol. 31 257-262. Greig, R.A. and G Senicfelder. 1987 PCB concentrations in winter Ilounder froii Long Island Sound, 1984-1986. BuIl. Environ Contaimxi, Toxicol. 39: 863-868. Grieg, RA. and D).R Weozloilt 1977. Trace metals in linfish froit the Nesc York Bight and Long Island Sound. Mar. Poll. Buill. 8: 198-200. Griswold, C.A. (ed.). 1981. The Barge Ocean 250 Gasoline Spill. NOAA Tech Rep. NMFS SSRF-75 1. 30 pp.
10ra 631 (innlndW.I), S.1.. cha lt. McCain, (.C CClark, ir, M1. NIyers J.E. Stcin. I) 'W [ioxn. J. T. landahl MMN Kli han and I, ararinasi. 1001. Multidisciplinary asscssmenw oi pollution it t*ree sitls in Long Island SoundiC. L'Stiuarics. 14: 2-99-305, lansen. P.D.. R.F. Addison and I).E. Willis. 1983. IIepatic ni croso-real O-dc-CthyIilases in cud f(-,adus mihIa) Theiir indu!ion ly Aroclor 1254 but ot lnl Ay.ocior 10115. ( lioLhe.'s,2,ix 74C: 173-175. IIarries, J.l:.. I.)A Sheahan. S.oblmgi. 1). Iathiessex n P. Neall, I..I Routledge, R. Rycroft,.I. Sumrpter and T TylOr. 199 6 A str'ey 0i, es-lolU'lliC
- tll\\ill' in Iwi-ed K
<ix a.dox l*'i w iand vale:r I il "loxiecol. Chent 15 1993-2002 lHar ri e.,.I D.A. Sh scha n.
- n.nhl.nn P > N tth Pics Nci
. 1 N l I, Sumpter, T. Tylor and N. Zatnan. 1997.. Estrogenic activity in live United Kingdom rivers detected by measurement ot' vitellogene-sal in cagcd Male trout. Iiiviron. TloxiCol Chent. 16: 534-542. Ilellou. I.- D. Mackay and B. Fowler. 1995. I3ioconcentration of poly-cyclic aromatic compounds from sediments to musceI ot finfish inviron Sci. "echnol 29 2S-2560. Hellstrom, T. and K.B. Doving 1983. Perception of diesel oil by cod ((-;ahis unwita I._) Aqu:lL. T',oxicnl 4 3031-3 15. Huiihies,.I. antd A.l. HeherL I9e c1.rythiocyi micronuclei in ii-ter ILI indcr (/I / l%'txoplnc.,wfleeU.C t iOlex'. x i*i I ttoo I. i te t cltS e t'ild nsrnveys during 1980-81,88 tiorn Virgiia to Noun Sciih dil Long Island Sottnd Arch. Environi Contain. Toxicol 20: 474-479. Hutt, P.B. 1985. Use of quantitative risk assessment in regulatory dccsioiin altinking undcr i l Iaiheh and silr-tx statutcs. hl Banbury Report 1 9. Risk Quantitication and RCegulatury Polien. D.G I loc, RA. Merrill and F. P. Peiera (eds.). Cold Spring Hlarbor Laboratory, Cold Spring I larbor. NY. Pp. 15-29) Jarvineti, A.W. and G.T. Ankiley 1998. Li i uic of LflIects i Tissueti FCSide Dic: DCxciOpIneit rI a Comprehensive DataXxt cibase l Aquicatic Orgunisms Exposed to hlorgaI ic and Oruxnc Chenicais. St. AC press, Pensacoli Fl.. 3I i pp. .lessen-Eller, K. and I.F. Crivellt. 1998. Changes in metaliothionein mRNA and protein after sublethal exposure to arsenite and cad-miutim chloride in juvenile winter tlounder. LEinviron. Toxicol. Chem. 17: 891-896. Johnson, L.L.,.J.E. Stein, T.K Collier. E. Casillas, 13. McCall] and U. Varanasi. 1992. Dioindicators ofContaininant [{xpiistre. Liver Pathology, and Reproductive Development Iii I respawnxini Fernale Winter F12 iIondei 1 !ilfirtmex 1'I'[C, UMVIjinlixls) I Onsi 1rhain and Nonurban Estuaries on the Northeast Ati c Coast NOAA/NMIFS Technical Memorandum NMFIS-NWFSC-1I Augttst 1992. 69 pp plus appendices. Johnstone, A.D.F. and A.D. Hawkins. 1980. Changes in the Respiration and Blood Circulation oxf Cod. (7/adis iioltiai I.. Induced by Exposure to Pollutants. ICES CM-1980/F: 46. JUilshamm, K., 0. Ringdal and O.E. Braekkan. 1982. Mercury concen-tration in liver and muscle of cod (Cadrt tnorht-I) as an evidence of migration between waters ofdif'erent levels of mnercury. Bull. Environ. Contain. Toxicol 29: 544-549. Kennedy, V.S. 1976. Arsenic concentrations in some coexisting marine organisms froni Newlbindland and labrador..1 Fisht Rcs. Bd. Can. 33: 1388-1393 Khan, R.A. 1987. Effects ofechronic exposure to petroIClim ihydrocar-bons of txo species of marine fish infected with hemoprotozoan, "'fi-vpanosonta mnirctanensis. Catl. J. Zool. 65: 2703-2709. Khan, R.A. 1990. Parasitism in marine fish after chronic exposure to petroleum hydrocarbons in the laboratory and to (lte Exxon Valdez oil spill. Bull. Environ. Contain. Toxicol 44. 759-7633 Khan, R.A. 1991. Influence of concurrent exposure to crude oil and infection with 7typanosia itinomauensis (Protozoa: Mastigophora) ott mortality in winter founder, Pseidoplderoonectes actrneamttus. Can J. Zool. 69: 876-880. Khan, R.A. and J. Kiceniuk. 1983. Effects of crude oils on the vas-ruttiiicni i i parasiles r xtwo secs o(iai ine Iis.. Wid'd l)isciaes 19:253-258 Khan, R.A. and.1. Kiceniuk 1084 Illistopatlhlogical ellects of'crudc oil On ktlaillc cCod tnloinOxi chrome CxposaLe. Can O /oii 02. 203S-2043. Khan. R.A...t Kiccniuk. NM.aic' and l. \\Viliiams. 108l. I.ong-term Il'cts,i Crxxdc ( tii On,\\tiiliiic Cod. ICIS C -i I 91* Il. 40, K iceniuk...JW, and R.A. K han. Ix,"i7. Icect xif peirilCuin hydriocarbons oin Atlantic cod, Ciidus motinria, flIllwing chronic exposUre. C'it .0. Zol 65: 490-494. Klcin..NacF'icc. 0...I,,\\. Cardhli and W..1 l3erry. 1,84 Il'liicts,Isilvcr on eags and larvae of the xvinter iloundei. 1rans Airier I2isi. Soc 13: 2C7->l Knickinex er. K and 1-. Steinihart. 1990. Patterns fevelyic organochlo-riie containination in livers of male Pleurronectifrites from the North Sea, xxinter, 1987. Nlr.rl.lii Biull. 21: 187-i89. Kocan, R.M.. 11. iIvon Westernhagen. M.L. Landolt and G. Fl"trstenbcrg. 1987 Toxicity of sea-surface iticrolaver: Effects of hexane extract Oi! Baltic hcrriig (htprea hilvgius) and Atlaitic ccod (TGaCrhus mortoa) embryos. Mar. Environ. Res 23: 291-305. Kullililxid.,\\ W i97 hlvcs2tiOaiinis 0n the o Icof seawter extracit of three crude eiggs,ii cas o!: cod (Gadis iLrI'iua I.. ). 13cr 1i. xcissn Koillinn. 'MNercsforsch 23 :15-i80 I an. . alllnd V I )ethlxelhen. 0187. Cadmitum 1 Skeletall', I)'rix'rd and Normally Developed Baltic Cod (fiodus morlta L1.). ICLS CM-1987iE 30. Laucnsteini. G. and A.Y Cantillo (eds.). 1998 Stimpliing aiid aiinalyti-cal iluuhods oe'die Nationail SWtais aild 'ieilds P iilolill NIhlaScl Watch Project: 1993-1996 update. NOAA National Statusi and Trends 'rogram. 233 pp. I.ogan. D.]. and I F". Wilson. 1095. An ecological risk assessment itetid'tce species Cx posed to colitarni anit inituiires. Environ. Tlhlxieil Choct 14 351-359, Iiongwxel..,\\.C 1977 A xeniclic lookait liishm egs ail1d xll. 1 'lUCx22iiiisi I0: 46-58. Longwell, A.C.i S ChC n, A. l lebert. J.B. Hughers aid D. Perrx. 1992. IPritlution and developmental abnormalities of Atlantic fishes. I.inviron. Biol. Fishes. 35 1-21. Longwetl, A.C.. D Periry J3B. lHtghes and A Ilebcit 1983. Frequencies of NMieronuclei in Matuire and hieluia1ture Erythrocytes o1i Eish ia ai Estii'ae olCChromosonic MLiation Rates - ReSrltsu itt Field Survev. On Windowilane Flounder. Winter Flu2W1i ier and Atlantic Mackerci. ICES CM-1983/IT:55 (Nt1Q7). Lonninti S. i 977. he 'l'fecLs of Iiko risk crude oil and oi piodLIucs tilt inarite fish larvae. Astarte 10:37-47. Lye, CM., C.L.J Frid, MIE Gill, D.W. Cooper and D MI Jones. 1999. Estrogenic alkylphenols Iii fish tissues, sediments, and wvaters from the U.K. ']\\ne and 'fees Estuaries Environ. Sci. Teclritl. 33.: tI 009-1I4. MacDonald, B.A. (ed.). 1991. SlatuS and Trends in Concentrations oif Selected Contaminants Iit Boston iHarbor Sediments and Bicta. NOAA lech. Memo. NOS ONMA 56. Macleod, W.D. Jr., L.S. Ramos, AJ. Friedman, DG. Burrows, P.G Proilaska, DBL Fisher and D.W. B3rown. 1981 Analysis of Residual Cho Iinated Hydrocarhons. Aromatic Hydrocarbons and Related Compounds lit Selected Sources, Sinks atd Biota orf the New York Bight. NOAA 'tech. Memo OCMPA-6h.128 pp. IMA DMF (Massachutsetts Division of Marine F-isheries). 1985. Assessment at Mid-Decade: Economic. Environmental, and Managrneent Problems Falit NMassachusetts Commercial and Recreational Marine Fisheries. -MassachIsettas Division tf'IMarine Fisheries, Boston, NIA. MBDMF PONi. 14224-65-500-10-85-CR. Malins, D.C., M.M. Krahn, D.W. Brown, I).D Rhodes. M.S. Myers, 131B. NtcCaim and S.-I.. Chan. 1985. Toxic chemicals in martine sediment and biota from MNIukilteo, Washington: Relationships with hepatic neoplastis and other hepatic lesions in English sole (Parophlys ieitis)..1I Natil. Cancer Inst 74: 487-494,
64l e see m s 11 S f el I tiC d bh oil e is IIs C M air. En vito IR - 1 7 7 265. MNaiiinseri I.. G. Staveiand, J.U. Sil i c-c, K.. UI g nd and.A II tIugen. 1991. Le elcs of envhionmental pollutants in iiale and teialc floundcr (Phtlici' / i's f!csts I..) anid coti Iradis-tiihi al caitiii (11.111il!U d~c }'car %988 near: of ;Il thc,..acr 61t, 11*( MIila [Lhc aireest rivei ! 'Norway. I Polychtlonated biphetiiys. Arch. Einviront Contain. Txieol 20: 35;3-3,60, McCart. I. S. aid D. Mackav 193 I ,91nhancin ecoi'onicolog'ici'
- ntodclhi, i
aid -sscssnm nt Ii,ironi Sci "'-l tol. 27: 17io0-1728 McElroy, A.LE and I.[. Sisson. 1989. TIophic translfr of' hcrIzoj l io ut cllc ho; 'ý bi cIent h:c I"FIrIIC Urgnimsms. Mlai. Environ. Rs 28: 265-269. McMahon. G., I 1I HUbti. M..I. Moore, JI. Stegeman and GN. Wogcn. 19Sa. Characinzatiuon of c-Ki-ras oncogncis i liver neoplasms of winter tlotInder from Boston Harbor. ACS Div. Environ. Chein. S: 299-3031 McNI c hNlion. G,.J LL Itict, i.I Stegci-ian and G. Wo\\an. 1 988b. Identification ofa c-Ki-ras oncoiene in a neoplasm isolated from svinTer 'lounder. NMi F711irwi Rct. 4, 345-350. Misra. R.K. J.F. uthc, CJ. MUSial and C.I. Chou. i98R. The Analysis ofn I ITrl,1tends it Coiinnamniit Levtl-in Caiadiaii Cod ((-olds inoiliia). 5. Tinie 1 rends-I077-1085, nploving a Multivariate Linear Model. ICE-S CM-1988/E:4 Rf. fD. Mitchell, DT, K.A. Sullivan, M. Moore and PR Downey. 1998. 1997 Annual Fish antd Shellfish Reporti Massachsietti Water Rcstilrccs tjIhoricy. I-Fvironrimnnrlil Qual,'i Is partilenil Technical Report Series 98-12. Decemberr 1998. 133 pp. Moore. M-1. 1991. Vactiolation, Proliitration and Neoplasia in the Liver of Boston I larbor Wintri IFlounder (Pseun/opleitronecies atiieriaomits) Ph TIlicsisn NIMassachusetts Institute of eclihnology and the \\goodds I oleit Ocentographi I nsittinit 260 [Pp. Moort. MJ.. R-. Smolosawitz[ DF iLeavitt and.1-Sictgman. 1995. I~vaitiiion of ChCmibCal Coiitaninant Il ectt in fie MassascilusetHts Bays. Finaiil Report to tihe Massachusetts Bays Prograrm' M BP-95-05.. i 99i. 3) pp plus Tables and Finires. Mvi oreau, C.,.I. Klcrks and C.N. I laas. 1999. Intetaction between phenaitnthirnic and zint in their toxicity to thi sheepslhead Itinnow (Cyprinodon variegaluS)o Arch, Enviion Contamin. it 1dxicol 37: 251-257 Murchelano, R A_ I)espres-Patanto and.I. ZsisoAski. 1986. A Ilistological E-valuation il'Gross n eIsions Ixcistd froim Cotninlrci.illy Important North At lantic Marine Fis-es. NOAA Tlech. Rep. NMNIS-37. 14 pp. Murchelano. R A. and R.E. Wolke. 1991. Neoplasms and nonneoplas-tic liver lesions in winter flounder. Pseudoplcuronecies anime-cantis. from Boston Harbor. NIassaclhusCtts. Environ. Health ersn. 90: 17-26. Musci, M.W_ B. Chauincey. P.C. Schmid, R.KHI. Kinne and L. Goldstein. 1990. Mechanisms of itercurial and arsenical inhibi-lion of tyrosine absorption in intestine of the winter flounder, Pseadopleuroinectes ameicamos. Toxicol. Appl. Pharniacol. 104: 59-66. " Nelson, D.A., I.E. Miller. D. Rusanowsky. R.A. Greig, GR. Sennef'elder. R. Mercaldo-Allen, C. Kuropat, . Gould, F.P 'lhurberg and A. Calabrese. 1991. Comparative reproductive stic-cess of winter flounder in Lone Island Sound: A three-year study (Biology, Hioctbemistiv and Chemistry). Estuaries. 14: 318-331. Nelsoi., D.R. 2000. Cytochrome P450 IHomnepage. http:/!drneison.mltte.edutmCytoclironteP450.html Newsted, J.L.,IJ.P. Giesy, G.T. Ankley, D.E. Tillitt, R.A. Crawford, .I.W. Gooch, PID. Jones and MS. Denison. 1995. Developiitent oti toxic equivalency flactors for PCB congeners and the assessment of TCDD and PCB mixtures in rainbow trout. Environ. Toxicol. Chetn. 14: 861-871. Niimi, AS. and GCP Kissoon. 1994. Evaluation of the Critical Body .tiirdei tiiCicncept based on inorgailiC :i id organic -iir urt, ttOxiciy i -raiitbow 11tiotl. (Oncor:hoichi tt ni kissi. ArchtI I 11n0ir n Coitarnhn loticol 26: 169-178. Nishiniitoi M., BI.It. Le [Ibcrhart t I. R Saihoi, C. iro-ic, U. Varanasi and J.I. Stein 1995. 1I7thctS ot'a complex miixture of chemical cont aminanti inl hepatic gdutaihione. I.-cyntcitc atd v-gluutanyistmitiut iynthetasc in I -tnt oIlIt t ulii+n-ec'is uellu/Ius) Initoni l 'loxiTiCul Chem.It I-46i NOAA (National Oceatic and Atmospheric Adhninistralion). 199 I. Seonid Suiinnary Ot Dati On Chemict l Coinceintrait Otios h Sedhnieiti Iron "Ihe Niaonal Status ani Tirnds i Irorat NOAA Technical Meniorandum NOS NMA 59 2Q pp. plus appendices. NCO.;\\A iNS&-T I National i ii and '*iiphcrii AdministrattoniNational Status and ITrends I'ograin I. 000. NOAA's National Status and Itrends web page (July "000) htttp:iiwwsiorca.s isnoatgoclprojeti osantihinlI O'Connor, J.S. 1976. Contalninant effects ott biota of the New York Bight Int Proceedingso 2nd Annual G(itlIand Caribbean Fisheries Iisljiit, Bal Ilaiboi Fi, Oct. 1975..1.B Ifignian (cL.l Gulf Carib. Fish. Inst.i Miami FL. Pp. 50-61 (tlol/insn. S and PL Lind1hul. i1970. D'ereiscd 'iitlnsn ii'cod 1( Got/ts iholitia I.)I Iront polluted waters. MNar. L irot a esn -` : 3-4. Pipe-Iitldstrimi IPA. and IM.J. lyady. 1997. Sa nergistic toxicity of stratzitt and orgainophosphate insecticides ioi 1aVclits the. response addition mixtue model. Envitoni Toxicol. Chem. 16: 24 15-2420. P'ayne. J F. C. fauld, A.C. Dy..I.W. Kiiiniul, atd U. Williams. 1981 Seleclivita 'inl.,xed-ttacticion IIyC nUse tnz nc iendtulction ill tiounder (Pseud/op'Liiuriectes aoicai ito'u its) collected at tile site of the BaIe
- iertie, NeJwfoundliand oil spill. Compi 1ioetei.
Phvsiol 79C: 15-19. Payne, JSF and I.L. Fancey I 0182. Pllect oI Ion itert tXOosurc to petriCricuLM ott Il ixtd Ifinctioni oxsgcnasts in fish: -titerhcl suppeor !Ou ilit" inse tiflte etltisite Hi bioloica! itotnitotisng Chctnosiplre.. t1: 2U7-213. IPayne, JF and PF. Fartce. 1989. 'Itflect o4 poivyctclic aromatic htdrocarbons on imnmune responses it fish: Chanlse in mclanoiiacrophage centers; ii floundei ('settdopete'ot oteetes americainius exposed to haindrocirbtit-conttaiait mted seditients. Mar. inviron. Res. 28: 431-435. Payne. SJF... Kiceniuk l.I. Pancey and U Willains 1988. What is a saie level of polycyclic aromatitc hydrocarbons for fish: Stibchrtiic toxiciti study ott stinter Itounder (I /stidopet'iiioilccet as c'ierieoiiius). Can J. I ish. Atalt. Sci 4 5 1983-1993. Pereira J J. 1988. Morphological effects of merutiry exposure ot awin-dowpane fIlounder gills as observed by, scanning electron microscopy.I. Fish Biol. 33: 571-580 Pereira, I.J., EI. Iewis, R.IK. Spallone and C. Sword. 1992. Bi furcation tlf gill filaments in Winter tlounder (f'leuronecies atericaiitits Walbatun) from Long Isliand Sound. 1. Fish. Biol. 4 1 327-338. Perry. I).M.,'J.B. Hughes and A.T. Hebert. 1991. Sublethal abnormali-ties in embryos of winter flounder, Pseidopileuronectes aneri-
- cauis, tfrom Long Island Sound. Estuaries. 14: 306-317.
I'erttila, M., V. Tervo and R. Parmanne. 1982. Heavy metals in Baltic herring and cod. Mar. Pol. Bull. 13: 39 1-393. Reid. RN., J.E. C'Reilly and V.S. Zdanowicz (eds.). 1982. Contaminants in New York Bight and Long Island Sound: Sediments and Demersal Specits and Contaminant Ef'ccts on Benthos, Summer 1980 NOAA Tech. Mem. NMFS-F/NEC-16. 96 pp. Renfro, J.l.., 13. Schtiidt-Nielsen, 1. Miller. P. Benos and J. Allen. 1974. Methyl mercury and inorganic mercury: uptake, distribu-tion and effect ott osmoregtmlatoly mechanisms in fishes. In: Pollution and Physiology of Marine Organisms. F.T. Vernberg and W.B. Vernberg (eds.). Academic Press, New York. Pp. 10 1-122
P A Isý\\ xl Fii': i S 6 5 iocsijadi, G. and W.. zoh.inson 1'5 eNtal regulation in aluatic aihllals: MNchalnisiti of Uptake, Iccis.LIlaltion aiand release Ifl Aquatic loisicology.: Molecolar, , ioclhctiical inld Cellilar Iceispectives. )..Matins and G K. lstraialei icd5s. Le Is Publishers. 13oca Ratoin FL. p 3Ill 7-4 1. Sang-c!alat.G I.. I.C. [rcenan and R. Crowel I OQl 1. restlcucUr abliornialitics in co.d (;aJlO*./to Feiai t~d.Uroclor i254 Arch Environ. Contain "Ioxlcol. 10: 6) 17-626. SchIn idt-N elson. B., J. Shel ine. D.S. Miller and N1. I)eldonno I977. tiet'ot',.i ef thvhinreurc tipoil nato ekht in. cclhu"al nolume and it~l! f e: ti'IdL I IiH ll "A.111ý',[ ]ICIL:MdCý' , jl.V*etfJ [,h tgI,
- C& 3 {~ '
caInis. It: I'ivsiolohical Responses oF MNarine Biota to Pollutants. "J Vcmrhcrg A, C-alaltc-e I'l: lhrh'c-nd W IV It Vet {cds. I. Academic Press, NY Pp. 105-117. Serigstad. H. and GR. Adolf 1985. EfleCts ofoil exposure on oxygen con1sLIuiptioin of cod eggs and larvae. NMar. Environ. Res 17: 266-268. Sherwood. Ni.. 1982. Fin erosion, liver condition and trace containl-Lint exposure ill Fishce iroin hrIee coastal regionls. Ilt [Lcologtcal Stress and the New York Biglt: Science and Management. G F. Maycr(cal. EstuaIr:se.1/cs 1
- d. Cioluhnli.
S(_ Shparkovskii, I A. 19x2 lEitects of0 )D)T on vegeitative processes in cod Sovietj.. Mat. Biol 8, 235-Sins. (5. C I: Co~shsnm .1.1). sCnpl:,cll :iid NIC. Nlurray. 7 DDT residues in cod livers from the nraritime provinces of' Canada. Bull. 17nviron. Contain. Toxicol. 14: 5OS-S 12. Sinlderinaun. CJ. 1994. Quantitativc EfIects of 'ollution ntn Marine attd NrLidroltinOus cFi-h oltition NOAA Ic ch. NMemo NMIES-F/EC-104, Woods Itoleý. MA. 22 pp. SkLre,.1.U.. J. Stenersen. N. Kveseth and A. Polder. 1985. Time trends of organochlorine chemical residues in seven sedentary marine Fish species from a Norwegian ljord during the period I)72-19'182. Arch IEnviron Contain Ioxicol 14 33-41. SiithO R.M. nmd C.17. Cole 1973. 1l'itýctns niecu oncc, rliOts of D)DI and dieldrin otn development in twitler hounder (Wsetdop/eirotzec's awteriscoits).. Iish. R-e. 13d. Can. 30 1894--1808. Sntolowvitz. RAM., NT. NMoore and JJ. Stegeitan. 1989. Cellular dis-tribution ofcytochrome P-45t0E in winter flounder liver with degenerative and neoplastic disease. Mar. F-nviron. Res. 28: 441-446. Solbakken, J.., K.H. FIatmork. T. Neppelberg and R.R. Sheleline 1980. Lirinary aitd hitlry metabolites of pltcnanthrenc in, the coil 'Ish I Iflochm,.s vilens). Acta PharniaCol. Ioxic ii 46: 127-132. Solbakket, I.E.. S. Tilseth and K.H. Palniork. 1984. Uptake and clim-ination of aroiatic hydrocarbons and a chlorinated biphenvl Ii eggs and larvae of cod Gt/ts mo nthca. Mar. Ecol. Progr. Series 16: 297-301. Solberg, T.S., T. EBarth and K. Wcstrheim. I982a. Effects of Illuminated Ekofisk Crude Oil on Yolksac larvae of Cod (Gadiis Morhita L.). ICES-1982/E. 58. Solberg, ".S.. A. Mangor-Jcnisen. B Seiigstad and K. Westrlheilt 1982b. Effects of l.ow levels of Ekofisk.CrUde Oil on Eggs and Yolksac Larvae of Cod (Gadils morhtma L.). ICES CM-1982i/E 60. Solberg, T.S., S. Tilseth. B Serigstad and K. Westrheim. I 982c. Effects of IL.owv Levels ofa Ileavy Fraction of [Ikofisk Crude Oil on Eggs and Yolksac Larvae of Cod (Gadus morhtoa L0). ICES CM-1982/E: 59. Spaulding. ML., NM. Reed E. Aniderson, T. Isaji, I.C. Swanson, S.B. Saila, E. Lorda and H. Walker. 1985. Oil-spill fishery impact assessment model: Sensitivity to spill localion and tinting Estuar. Coast. Shelf Set 20: 41-53 Spaulding, MI.., S.B. Saila. E. Lorda, I1. Walker, E. Anderson and J.C. Swtanson. 1983. Oil-spill fishery impact assessment model: Application to selected Georges Bank fish species. Estuar. Coast. ShilI'ScL 16 5iI-541. S pies. IC,.t and I).W. Rice.Ir 19r I. I'i F cts of organic contaminants tnIT reproduction of the starry 0i ilnder ! olictitis shtellat, in San I ratcisco Bay II RCprtiductive SuccesS to i-,l t Uptur Cd ill Sti) Francisco Bay and spawned Ii tihe libotormy Mar Biol. 98. 191-2{"t0. Spies. R.I 1-) WV Rice JI. and I. Fehlto. 19ui Dl _ ct ol-mi-attlc contaminitants oil reprodIetlICiOn o the starry tlounder Pf'/cichithvs stellats in San Francisco Bay. I. 1 Hcpatic contamination and Intixed-flinctioil otidasc M"1:01 atlisilt during ihc reiroiductivC seasorl. NI*.r. 1 1 18t-I St) Stegeritait JI I;. feng anid E A. Siowbcerger 1987. induced Ce Loclhtr(ifie P-150 ill tvitlr Iutitdcr (/I'.c's/:p/tiiie cll tctYititS - cemitis) froin coastal MassachuLIsetts evalunoted by catalytic assay and monoclonal antibody probes. Can..1 Fish Aouat. Sci 44: 1270-1277. Stein. 1.t"., TK. Collier, W. Reichert, F. Casillas-T Horn and U. Varanasi. 1992. 1ioindicators of contaminant exposure and sub-letih l ctlIets Studies with bettltlic fis in Ill L -,t Sotundt Wtashinoton. Environ. Toxicol. Chem: I1: 701-714. Stork. T. !93.I CF Letels Correlated eIthhl. "h . c Uns-S}i.droites itt Cod (GOIus morhit LI. )- ICES CM-1983/1: 510. Stiti Ititers..I K. ind K '\\. Rose 1987. h Ihe iole of'intei actions atli tic, cnivironmental enoditions it controllitg historical \\shericO tari-ability. Estuarties 10: ..5-266. Suetr. G.W., IF, A.E. Rosen, 1. Linder and D.F" Paikhurst 1987. Endpoints for responses of Fish to chronic toxic exposures. lInviron, itxicoh, Chetit 6: 793-8{090 Suter. GCW.. II and A.E. Rosen. 1988. Comparative toxicology Ior risk assessment of marine fishes and crustaceans. Environ. Sci. Technol. 22. 548-556 Swedinark, M. and A Grantnio. 198 1. Ef'dcts ef mixiures of heavy itetals and a surlanctint on the developitient of'cod (iGadus iitlihut IL.)1 RtoP. P.-v Rcun. Cmts. till Euphlr Mer 178: 95-103. "lTay, K.1., K.G. Doe; S.I. Wade,,.D.A. Vauiglthn and R1/. Fferritgan. 1991. Biological effects of conlarninants ill Halifax Harbor sedi-itent. Canl. Tech. Rep. Fishi AQual. ScI. 1774. 1383-1426. Tilseth. S.. T.S. Solbcrg and K. Wesirheii. 1981 Sublethal Effects of ithe Water-soluble Fraction of Ekofisk Crude Oil on the Early Larval Sitaes,if Cod (Gau/is moritgi L..) ICES CM-198 /E: 5" Tiilseth, S., T.S. Solberg and K. Wesirheiit. 1984. Sub:letlal effects of A ihe -itter-sol ulie fraction of Ekofisk crude oil t ilte early larval staecs of'cod (Got/its mor/lI. LA. NMar. Environ. Res. I I: 1-16 Truscolt, B, J.M. Walsh, M.P. Burton, J.!. Payne and D.R. Idler. 1983. Eflect of acute exposure to crude petroleunt on soIsie repro-duicteiv hormones in salnon and flounder Comp Biochem. Phvsiol. 75C 12 1-130, Turgeon, D.D. and T P O'Connor. 1991. Long Island Sound. Distributions, trends and effects of cheitical contamination. Estuaries 14: 279-289. ULS. EPA (Environmental Protection Agency) 1984. Federal Register 40CFR Part 300. October 15. 49: 200. Boston, NMassachusetts US.. EPA (Environmental irotection Agency). 2000. Aquatic Tocxicity Inlorinration Retrieval (ACQUIRE R I Database. hittp:i//wvsvw epa. gPov/med/databases/aquire. Ittitt I. U.S. EPA (Environmental Protection Agency). 2005 Priority Pollution list at http:iit-wv.wscorecard.orgchern ical-groupsoiote-list.telshort list name=pp. Van den Hurk. F, M.Fl. Roberts and M. Faisal. 1998. Interaction of cadmium and benzo[alpyrene in mummichog (Fund/ilis hetero-cilusl: Biotranslbrmation in isolated hepatocytes. Nar. Environ. Res. 46: 529-532. Venglarik, CJ. and D.C. Dawson. 1986. Blockade of apical K chan-nels in flounder (Psedopleuronectes americatis) urinary blad-der by inorganic mercury: Time dependence due to apparent inac-tivation of Hg++. Bull. Mt. Desert Isl Biol. Lab. 26: 1-4.
66 ~iOV Vover. R.AA -.. A. Cardi.F I I I lvCIshc and CGI. llh I I an 1982 Viability of embrvos of the wmiter IHounder. f.Veudopl~eInrooeMes nlercicoi"is. esposed to ixntI-cs of :admnitl and silver it comtt-bmituiOn wit" sClCCtCd 1ixcd se1aiinliCS. Aqiatic loxicol. 2: 223-233. Wall. K.L. and J. Crivello. 1998. Chlorzotazonc metabolism 1w sein-LCI iloLutIder liver IIIcroF o ! I-i % i tin.ieCC !ii cxis\\cticc ol'.a CYI'21E -like isoitrm in n elcl ts. "osicol. Aprl. Ilharnacol. I Il 98-04. Waill. K1,.jesscn-I.illic and J, Criscllo. 9 ,Assessmenlt o1 vaio'nu btomarkcts 'n wviner 'ilondet -oit co)*1sti 1Massachusetts-USA. Environ. T-xicol Chem. 17 2504-251 I. Waller. \\.-F. M.I.t. DahlbIer. R E. Spaiks and J Cuirns. Ii. 1971 A computer isiulation of the etflects ol'su, perimposed mortality due to poll Litants on populations of fathead minntows (i,,eph/als pwotel/s) J IIish. Ies Bd. Can 28:1107-1112. Wallis, I.G. 197S. Modelling the impact of waste on a stable fish pop-ulation. Wat. Res. 9: 1025-1036. Weis. P-J.. W'is, C. Chue aid :\\. Gireinieg 1992. C reated Municipal wasteVaters: Efflcts of'organic tractions on development and 0-iro\\ h ul'!ishes. FIi-'iron -*oicoI. Chcm 1 1 Wilson. K.W. 197'7. ACLItC tOxicity ot oil dispersants to marine fish lirvlc. Maj BioL 40:0 -4 Wltfe. D.A. D. F. Boesch, A. C i'labrese, J1 I see CD. Litchfield. R.1 Livingston, A.D. Michael, JIM. O'Connor, N. Pilson and [Y/. Sick. 1982. Ellects ottoxic substances on communities and ccosystems. In: Ecological Stress -ind the New "Yoil Bight: Scince and -'ltana'escii.. I. i ye is, I marinc Rcsearch Fed., Columbia, SC. I'l 67-86. Wolke, R..I. RA. Murchelano, I I) Dickstein and C.J. George. 1985. preliminary evaluation of the use of macrophage aggre- =iIcs (NIA) a3 fish illmoniots Btull. Lnviron. Contai. loxicol. 35: 222-2-271 Zdaiowicz. V.S. DIF. Gadbiis -id 'IV.W. Newman. 1986. I-cvels of Oiiac and inorganic Contamiiants in Sediments and Fish Tissues and Prevalencis o' Patliolouical Disorders in Winter Flounder from Estuaries of the Northeast United States. 1984. 1EE Oceans '86 Conference Proccedings. Washintitont. D.C.Septeatber 23-25, 1986. Pp. 578-585. Ziskowski. J J, L. Desprcs-Patanino, R.A. Murchelano, A.B. Howe. D. Ralph and S.. Atran. I Q87. Disease iII commercially valuable fish stocks in the northwest Atlantic. Mar. [toll. Bull. 18: 496-504.
iiAviTAT [.OSý I-ND D1,:iiRA'-1 %!"[ON 6-17 Chapter V The Effect of Habitat Loss and Degradation on Fisheries LINDA A. DETGAN The Ecos,stem Cer/er lfaiuine Biological Laboratory W4oods Hole. MA 02453 ROBERT BIJCHSBAUM A'lassac/oSCII,i in A taiuoo SociCetly 346 0;ioperioc Rood ffl'nc,n,, V4t 01984 The importance to the Uniied States 0/ the fisheries on its coasts con scarel y be exagugerated, whether we coasicler the amount i!"whoilesome lood which lhYV yied, thepccior' I, va/e o/ their iprod- /c'ts. the number ofmenet and boys o,-)r whom they fitrnish profitable occupl*ati.o, the stimults to ship and boot building which they sufpljy anid, not the least of all, their service as a school fbr 'Secten. froin which the merchant-marine, as well as the totvvy ofthe countr3y, derive their most important recruits. -Baird, 1873 have changed the suite of species that can survive in a given area. We can make reasonable predic-lions about which species will occupy certain habi-lat types under certain management regimes - for example., how the returnl of lbrests to much of New England as farms were abandoned has influenced the distiribution of such species as black bear, white-tailed deer, and moose. For a variety of rea-sons, our understanding of the relationship between marine fish and their habitats is, by comparison, at a primitive state, and our predictive capabilities are minimal. The purpose of this chapter is to review human impacts on marine fish habitats and address the question of how such impacts might be affect-ing fish populations superimposed on fishing itself and natural environmental variation. INStlORE AND OI;FFSIIORE FisH HABFIATS Much of the information that relates the impacts of habitat alterations by humans to fish populations will be taken from studies of nearshore and estuarine fish, since a number of major studies have been carried out there. It has been recognized since the early I 800s that nearshore marine habi-tats, particularly coastal embayments and estuaries, are important for the survival of some species of fishes and shelifishes. In some parts of the country, coastal species are the major component of INTRODUCTION The notion that the abundance of an organism is to a large measure a function of the quality and quantity of suitable habitat available to it has been an integral part of the science of ecology since that field of endeavor came into existence in the 20th Century. Perhaps because the habitats beneath the sea are hidden from direct view, the connection between fisheries and habitats has only recently received much attention from scientists and fisheries managers. In the terrestrial realm, we know a great deal about how human alterations of the landscape
68 conmmercial and recreational fisheries. Even where the direct harvesting of estuarine and coastal species is not nILiericallV or economically signifii-cant, estuaries and coastal embayinents may still be essential for fisheries because tiey %; Srv as nurs-Cries f'or the juvenile stages of species harvested offshore or for the prey of commifercially important species. The high productivity of bays and estuaries. particularýly those with salt marshes and other vege-tated habitats, may help support offshore food webs (Odurn, 1980; Deegan, 1993). Thus.nearshore arid offshore habitats are linked ecologically. What we can learn from tihe impacts of habitat alterations on nearshore fish will be relevant to habitats further otfshore, such as the hshingi rounds of Georges Bank. Because it is a popular place to live, visit, recreate, and conduct business, the coast has been measurably altered and degraded by a variety of humlan activities: (I ) urbanization, (2) agriculture, (3) alteration of water flows by roads, railroads, and dredging, (4) diversion of: f'reshwater flows for alternate uises (5) overharvest of biological resources, and (6) pollution from point and non-point souirCes (Table 5. I). There is also an under-standing of the physical disturbance of berithic habitats by mobile fishing gear. Because this type of disturbance is so widespread and intense both inshore and offshore, many scientists and managers are concerined that it could be impacting fish popu-lations, perhaps inhibiting recovery of overfished stocks. DEFINITION OF HABITAT Essential fish habitat (EFH) means those waters and substrate necessary to fish for spawn-ing, breeding, feeding, or growth to maturity. For the purpose of interpreting the definition of essen-tial fish habitat: Waters include aquatic areas and their associated physical, chemical. and biological properties that are used by fish and may include aquatic areas historically used by fish where appro-priate; substrate includes sediment, hard bottom, structures underlying thewaters, and associated biological communities; necessary means the habi-tat required to support a sustainable fishery and the managed species' contribution to a healthy ecosys-tern; and "spawning, breeding, feeding, or growth Table 5. 1. Major categories of hunIaii impact on coastal aquatic habitats. -,,;V'EG()RN" iEXAM PLIL Physical habatat loss draimae, shoreIne dredeii, spoihl P disposal Hydrology changes. Ifreshwater diversion or withdraw-x II al. tidal constriction due to cause-twrays or culVCets, hdVdi0clecti); planits Litrophictinon ertilizers, sewage, runoft, septic i VsstCeis, land use cSediment delivery i ncreased due to soil erosion, chan-'es decreased due to upstream dams ni pS hlitroc(luCCdl species Phtroewmili',. Lieen crabs Fishi -j nicthoc.s-physical impacts F Colo-ilinii iais I'll) C; IchaniLes ill sea-level G -irawls, clamn rakes, scallop dredges 'heavy metals, hy drocarbons, organics., waste dumping/debris hikvher wvater temperatures, increased sorim eveils. !loodinr jof marshes, declines ill 1productivity to maturity" covers a species' full life cycle (Federal Register. 1997). \\Ve have chosen. to define habitat broadly lor this paper. Habitat is that part of the environment on which organisins depend directly or indirectly to carry out their life processes. For fish, this includes spawning grounds, nursery areas, feeding areas, and migration routes. The definition of what is a habitat for a particular species will vary according. to the number and extent of life processes used by an ecologist to delineate a habitat. In this chapter, we will consider habitat as those parts of the envi-ronment that together make a place for organisms to survive and prosper. This includes the physical environment (such as structure provided by plants, sediments or temperature), the chemical environ-ment (such as salinity arid dissolved oxygen), and the many organisms (such as plants and inverte-brates) that comprise a food web (Cronin and Mansuerti. 1971; Peters and Cross, 1991; 1-loss and Thayer, 1993). Defining and describing what habitats are
ii A rll A i ij I Ný ýI\\ol) DI Fý;NA IA' 1, 69 essential to a species is comphcated. Difterent life history Stages May require a different habitat, or an organlisIn may use a variety ot habitats during each of its life stages. For example, menhaden require at leist four di cfierct habitats (Deegan. 1093). Hey spawn offshore (I), then depend on tidal currents set up by river discharge (2) to bring larvae into estuaries whvlere they use salt marshes (3) for feed-ing and protection from predators. As juveniles, they use open bay areas (4) to grow to a size where they can move offshore (back to 1 ). A number of common species in the Massachusetts region have populations that make regular. seasonal migrations between estuaries and nearshore coastal waters. These include winter flounder, summer flounder, three-spined stickleback. DlLieSiih, Striped bass, Atlantic silversides and a variety ofdiadromous species (Table 5.2). Physical structure is the most visible aspect of a habitat and is therefore the basis for most habitat classifications. Kelp beds, seagrass meadows, inter-tidal marshes, intertidal and subtidal mud and sand flats, or offshore ledges and banks provide distinct physical structures that serve as habitats for fish and other marine organisnis. I ess obvious struc-tural components are fironts separating different water masses or plumes of turbid, low salinity water produced by large rivers. Structure alone is not sufficient to provide a functional habitat for an organism. Habitats can be dysfunctional, even though the basic physical structure is present. if aspects such as food webs or primary production have been altered. In addition, environimental prop-erties such as temperature, salinity, and nutrient (food) availability greatly influence the use of these areas. Some habitats cannot be assigned to a specific location. The convergence of the freshwater plume of a river and the ocean changes its location with the discharge of the river and the tidal regime. These areas are an important pelagic habitat and support dense populations of zooplankton that are critical to the survival of larval and juvenile stages of fishes (Townsend, 1983, Govoni et al.,.1989W Grimes and Finucane, 1991; Govoni and Grimes, 1992; Doyle et al., 1993). GENERAl.. CATEGORIES OF IMPACTS From an ecological perspective, it is useful to think of hunian impacts to marine habitats as fitting into three categories: I. permanent loss (e.g.. fillino of a coastal wet-land).
- 2. degradation (e.g.. eutrophicarton ', and
- 3. periodic disturbance (e.g. mobile gear).
The first results in a loss of habitat quantity, the other two in a loss of qUality. All three may reduce the ability of a region to support fish, however they differ in that the first is irreversible, the second may or may not be reversible, and the third is gen-erally reversible once the source of disturbance is removed. Recovery times for the second category depend on the nature of the agent causing the degradation (e.g., very slow for PCBs vs. relatively short for nutrients once the source of contan iination has been removed) and the physical characteristics of the region (sediment type, hydrodynamics, etc.). Recovery times for the third category will vary depending on the intensity and periodicity of the disturbance (e.g.. how frequently trawled) and the nature of the habitat itself' Superimposed on these human-related alterations are natural fluctuations in habitats, such as storms. and long term climatic changes. HABIT-ATfl QiANTITY ANt) QuAIJrM Habitat quantity is a measure of the total area available. while habitat quality is a measure of the carrying capa-city of an existing habitat. Documenting the former is reasonably straightfor-ward, particularly for some nearshore habitats, such as salt marshes and eelgrass beds. The extent and rate of actual loss of coastal wetlands have been well documented for parts of New England and elsewhere over the last.few decades by a number of researchers and agencies using aerial photography and ground surveys (Dexter,. 1985; Hankin et al., 1985; Costa, 1988; liner and Zinni, 1988; Dahl, 1990; Field et al.. 1991; Tiner, 1991). Maps, how-ever, do not indicate whether a current existing coastal wetland or seagrass bed still functions as it had historically. Less is known about the distribution of off-shore habitats in New England waters than nearshore habitats and about how such habitats have changed as a result of human and natural fac-tors. Certainly scientists and fishermen have long been aware that certain underwater features, such
70 [)/:i-: ; 'table 5.2. List of fish species occurring ill coastal Massachusetts waters and their relationship to estuaries. Fisherx indicates species historically or currently taken in either commercial (C) or recreational (R) Fisheries. I luman impact effects are keyed to Table 5.1. Possible impacts on each species are based on documenled cases and assessment of habitat requirements of individual species by the authors. Comnmon Name [Scientfilc Name litaided fullitFish fu d ,b /u)IuI' B Iackusc shinni- \\<orii P ,uu~.,-/i Bliidle shiner Ot,/ri Dt/rel;namus 1111Mit lroul (introiuced) l lt u,-/t;, C ha in pickerel [~so v luger Whit, len-etch 1w On..,tWrr/-uju/ Diadromous Alfe \\ vi te A Iu 'u psifeduhurenguis .Amiericant eel luguinla ros/ruta
- i-*7
- 7;i-{'e
- ~
~ Aimierican shad l1,' sap.hiissi.no id iit d { 7 s] fii 0,i........................ iiS 7/7 777 T~ i. :....................... Aliianuc S/,Iilmon " toio suri/i AItlantic stutn'ooii i!CCon ii tS( *t r h u lCiS ltiunack .,trrriu>. I/o;7 t oesi,.It.ljs Rainbot smelt Oo-erits 5 .or.. x Sea lamprey mernizonmuiis S ~irt nio.k trout
- 5.
lj'uios;t !ubo'b,>~i Re sIdent fi ~xoidstickleback. Gustet-o~sbeos Wi/euibru U Fliourspine sticklebkac Apeltes oito(frbrct's l*77;_ ~ et~ct -----...... 7
- 7. 77....777
( irithhv if 0.2,.cN'/)/i/,ttl, t'/*?tk/t!, I losehoker i rirw-ws jes fu /Ctbus 11Luittd -Sil erSides IA rid/it li-i ,hstu Lon*horn sculpin iAxvooce/pm/tus ocuroccmio.'iz osus Muinmiehog 1'undo/os hclco'riur ý Naked gob)' Qob'iosoruc; bostri N lurspine stickleb'ack Plun'itito ts gl~lium NoirtIiern pipefislh ngT.ithii.rTci.s No ihe i ip ipcu r. Sp/tctoi'oiTdes flitatttthlttt (iNte o-ad tistli Outsal"I tt Itn .g i 7 17ie {;{ c-*........................ Sheepsthead minniiiow. C mprirmidon varie gaivs Shor thorn scu 1pi tmAlvyocepholis scorpiiis S11moothti lounder Liopseita putnam! S6ickleback Gastetosleuis spp, Striped kil*ifish Fudidthus maoilis -hreespine stickleback Gasterosteus actleatus Pe tui k o H huimaii hilmpact l........ ........ S i ~i' i ...........I. /........... N: C R (C R C Rt C R/ Pelatic 1caic i l-gimtic t'dti_'it N: N: X N: x N: x N: N: B enihic t td hic Bv ihic It nihic Blit uttc loithi ni PeBmlagic .. m--- hic ......7....... Benthic C I B~e Ih-III C Brithic B.*nthic B. ih{iic X N: X I NXiJ I) X i X x N:XN XIX x-- Nursery Atlantic nienli*iden lrevoistia. ovranmtus C R 'Pelag'I c-i x IN :: Atlantic silversides WAenidia meidia c elag[ia xc
- x N x
Atlantic tonicod xficrogad/ms £omcoc/ Benihic
- x I x Bay Anchovy
- Anc'hoa milcilli I
lPelaiic Nx x 1 x BluheFish Itoo,,atomus saltatrict C R Pelaici Cunner 17alogolbio adsperri.,' i C R B[nlhic x x x xNIN: Mlullet itug-l cep/hlus t Biienthc t N Pollock Poluchims vire,-,s I C R Pelagic x x x L_ ?/ Striped bass !lorone' s(yatilis C R Pelagic N: x x N: N: Striped mullet AiuuolI cephalus' C R Benthim.X Summer flounder I Puru-ichihys,,Ieniois-C R Benthic Nx: j Wiautoer Iod ulo onleuss C R Benthic I x x x W~inter flounder Ptru/opl)ettr~oectuls amoericroius-C R Benth \\jN: x
71 common Name -tkican plaic Atlaniti cod iScientific Namet (htr/i tiltit / lt l'isimerv' Zo/Ane Humnan Impact H K I Atlantiic herringl Atlanticn.iactkercl \\tL nut..,crdclcih Atl'un1ii. Spilt l*_iiinp-Sncke1r ,\\tlantii-C1-x. x o.I..S.i h 1......... Blacir se ibais C ti'ca hacir itlt' 1t'tt C t',o tt I C 'II I Si S i b 1 70sIIts .4iru1 ci a hy' s IIR'tutl tttt h '0 tO.; Btlotched CLISk-Cel BLtuterfmlsh (oha Congeru cc! I'-usk I)iubcd shatnny FOIBIOu ptI floun11der Mo'icltion 01 at Pejn tius tri rconthios Iuclotelt ntrott crittcdtir Lunit;ctto.s ncttccitin / ib(ilitt C ) tr ttt s I (joosclish Haddock I It hirc ip iiardf7h iackerel siad Not thern kiniifishi Northern scarohin Northern set ictt Ocean perch Ocean pout Ocean sunfish I o/ihitI arncricantns 1A I. et/l) ratnutlu ttr'glefinits et/tt intitet Ct r icpteu t o'iimpits LXcap CtrS *,UC01ti cIt t l'riw intrs cuirolmit s !Spit irrtcuic 1.ot ert, -. srires martnlis yaltrt)o~treeS cittericarouis Offshore hake iAler/*ucriits a/d ic/its C Pie rm it ] /'tiintoluls for ctalts R-ad-iaited sliaininv Lvtli tItii t "R o l il
- h o a:..............
g u e h s I iI _I............... Red hake t 1 ii chItto C R Rock gunnell ['hotanneln 1/t Scup Stenotontts chrvsop~s C R Sea raven Ietr'ntiptertto atericanits Silver hake Alerlucciris bilinearis C R Sk-ates.spp. Rioat s p... Smooth dlogfish AlttsfeIns rants C Smooth skc Ru/u sc ow C Spiny dlogfish -~ Str/r iuihrsC Striped searobin prionontu rdoans Thorny skate Rica rucdatd o Weakfish OCinoscion re,'ais C R White hake L.rophvcit lett, it C R Whlite mnullet JAhfottll 'ittente_ -C R_ W in dowvp ane - Sr'rtphthcdoitsrtnus ttaI1Sf,__ C K_ Winter skate Rariaa rrel/ri e Witch FIlounder G/ývpu'oceyphulus cinoglosstts C R Yellowt~ail flunder Limratndrt f rrtgitnea C R Physical habitat loss; Hydrology changes; Eutrophication; Sediment delivery changes; Introduced species; Fishing methods-physical impacts; Contaminants; Global climate-changes in sea-level.
-7 fI) & B 1 : ( as Geor-es Bank. are a(tractive to diverse marine organisms and have had a general idea of the bot-torn types in different regions through bottom sam-pling by trawls and dredges. The recent develop-nIent of sidescan sonar, high ICsolution seisiic profiling and echo sounding, and video-equipped remotely operated vehicles (ROVs) and sub-mersibles has stimnulated nm*pping efforts in certain sections of GuI f of Maine, particularly the north-east section of Georges Baink. Stellwagen Bank, Jeffreys Bank, and Swans Island (Valentine and Lougli, 1991 \\,'alentine and SchiInLick, 1994; Auster et al., 1996). The degradation of habitat quality, such as through siltation and alteration of salinity, food webs and tiow patterns. lnay be just as devastating to the biological community as a loss in quantity. Siltation caLiSecd by land-based erosion may smoth-er a smelt spawning bed in a tidal river just as off-shore deposition-of dredged materials may smother the benthic eggs of Atlantic herring. The physical structure of the habitat does not need to be directly altered for negative consequences to occur. Anthropogenic alterations in the tidal flow to a marsh frequently results in the invasion ofsalt marshes by /hragmiles aust*'alis, generally thougllt to be poorer as a habitat than the plants it replaces. Habitat loss and degradation are interrelated because habitat loss is the ultimate end point of gradual declines in habitat quality. [TIE QijES)TION OF SCALE The effect of habitat loss on organisms depends to a large extent on the scale of the loss. A single small loss may not, in itself, cause an observable effect. However, tile cumulative impact of many small losses may be quite significant at a regional scale. For example, the diverting or damming of one river, although locally important to the species in that river, may not have a regional impact. However, if enough water is diverted from the many rivers flowing to the Gulf of Maine,. the coastal boundary current setup by freshwater dis-charge and important to the survival of many off-shore fish could be altered (Townsend, 1991; Doyle et al., 1993). Similarly, the loss of one acre of salt marsh or the destruction of a small patch of cobble habitat may not have a detectable effect on fish. particularly where there are enough i atkected areas nearby to compensate For the loss. The cumu-lative impact of many small losses over tine may, Iioweveri. ultimately lead to a severe impact on a fiishery. As unimpacted habitats get smaller and more fragmented, the capacity of the populations to recover from natural catastrophic events as well as human-induced stress is likely reduced. The small incremental increase in a stress. such as.a increase iI nutrient loading from a new development, may be enough to turn the corner from habitat degrada-tion to loss. Most environmental regulations gov-erning developments require assessments only on a site-by-site basis and cumulative impacts are not considered. Management of fisheries occurs at a regional scale, but the changes in habitats that may uiltiniately lead to a severe impact on a fishery are the result of cumulative impacts at much smaller scales. Over a long enough period of time the SLIM of all the small changes may result in a large imlpact. Loss ovF H,\\irTvr QUANTITY vobodh knows how much salt marsh existed along the Atlantic coast oq /Norlh America before the Europeans arrived. NtO matter hoin much n'as here, the set-tiers began to change the existirg amount ahnost immediately -7Tal and 7Tal, 1969 [IIt...ING AND OUTRIGHT Loss OF COASTAL. iIABITATS Loss of coastal wetlands due to residential and industrial development has been severe in the United States. Recent estimates-suggest that about 54% of the nation's original 915,000 kmin of wet-lands (freshwater and coastal) have been lost (Tiner, 1984), and over half of the nation's original salt marshes and mangrove forests have been destroyed (Watzin and Gosselink, 1992). A particLi-larly intense period of loss occurred between 1950 and 1970. Boston HLarbor is a local example of this
LV '-1 '7:I Iý 1I Figure 5.1. Alteration of BIston Harbor by tF in.-1775 to 1990 (fon MAVPC Boston Harbor Islands Compiehe sive Plan). The grey patterned areas iidicate landfilt. national trend (Figure 5. 1). From 1775 through the 1970s, the physical shape of Boston Harbor has been drasticallv altered by filling. The part of Boston that is now the North End and Beacon Hill was originally a peninsula connected to the main-land by a narrow strip of upland (the Boston Neck) with extensive salt marshes. The Back Bay, a densely urban neighborhood harboring some of the tallest buildings in the city, was once a shallow estuary with extensive salt marshes. South Boston and Charlestown were also originally surrounded by tidal marshes'that are now destroyed. Filling connected with btuilding Logan airport alone amounted to 2,000 acres. The wholesale loss of coastal habitats from human activities has been halted, in large part due to. federal wetlands protection mandated under the Clean Water Act of 1972. At the state level, Massachusetts has one of the most stringent coastal wetlands protection programs in the country through its Coastal Wetland Protection Act of 1964 and the Wetlands Protection Act and Regulations, passed in the 1970s. Estimates of the change in the acreagte ot salt marshes that has occurred after the passaoe of wetlands re-ulations in Massachusetts indicate that losses vary from vitually zero in less developed parts of the Massachusetts coast to about 9% in a fourteen year period inl oe highlyv urban area (studies summarized in Buchsbaum, 1992). Of the approximately 15.500 acres of vegetated estuar-ine wetilands between PIlurn Island and Scituate. Massachusetts, about 24 acres (0. 1 5%) were either converted to uplands or changed to nonvegetated wetlands from 1977 throughd 1985-1986 (Foulis and Finer. 1994). Although this is a much smaller num-ber than what occurred in the 1950s and I 960s, nonetheless small, incremental losses of coastal habitats still occur from public works projects that are exempt fron regulations, from illegal fillinrg froom boater activities, and firom the construction of small docks and piers. The latter often involves dredging several hundred cubic yards of material and re-arranging the shoreline to one more suitable to human use. There is less intormation on historical changes in acreages of subtidal eelgrass beds and subtidal and intertidal sand and mud hlats than there is for salt marshes. Like salt marshes, these areas provide important habitats for a variety of fish and shelIfisli species (Whitlach, 1982: Thayer et al., 1984; Hleck et al., 1989). Undoubtedly, many of these habitats were filled along with vegetated wetlands as popu-lation centers grew around estuaries. In addition to filling, these shalltW, subtidal areas are affected by other human activities. Power boats, for example, can directly remove submerged vegetation and associated attached organisms (Thayer et al., 1984) and resuspend sediments from tidal flats. DREDGING SUMTI DAL BENTI'HiC HABITANS Many New England coastal communities depend on dredging to maintain their harbors for recreational and commercial uses. Fioom 1960 to 1981, enough material was dredged from Beverly. Chelsea, East Boston, South Boston, Gloucester, New Bedford, Fairhaven and Salem, to fill a one square mile hole 4.5 ft deep (Pierce, 1985). The act of dredging, as well as disposal of the dredged material, has an immediate affect on the benthic community. In the past, dredged materials were often used to fill salt marshes and tidal flats to cre-ate more dry land, so a number of coastal habitat
tyPCS \\Vere atl'eO d be dredging Much ofthis sedi-ment had toxic levels of chemicals such as PCBs. PA-s, or metals, hence the impacts go beyond just physical alteration ofthe habitat. Dredge spoils have also been deposited in ofi.:shore disposal areas such as the Massachusetts Bay and Cape Cod 13,1y Disposal Sites. Although regulations now require that such dredged material meet certain standards in relation to contaminants to be considered suit-able for oitshore disposal, this practice clearly alters both the inshore dredged and offshore filled benthic comi tIn i ties. Dredging causes losses of submerged aquatic vegetation, such as eelgrass. through both direct and indirect causes. Dredging shallow subtidal aceas has resu lted in the diiC ect loss oi'Ceicrass in a number of areas around the coast (Costa, 1988). Declining light penetration and smothering associ-ated with the turbidity plume caused by dredging also cause indirect losses in submerged aquatic vegetation (Thayer at al.- 1984). Since they are not as well-delineated as intertidal habitats, eelgrass meadows are more likely to be inadvertently dredged even \\. ith current wetlands protection 4-ulations. Dredging alters i nti tidal and sutbtidal habitats by making some areas deeper by sediment removal and others more shallow by filling. In addition to being primary habitats for important shellfisheries, shallow subtidal and intertidal flats are important feeding areas for many flatfish, including winter. summer, and windowpane flounders (Pearcy, 1962: Tyler. 197 Ia; Berogman et al.. 1988: Saucerman, 1990; Saucerinan and Deegan, 1991 - Ruiz et al., 1993). Dredging eliminates feeding sites for many fish by' altering the species composition of the invertebrate prey within the benthos (Whillatch, 1982). Tyler (1971 b) suggested that the loss of tidal flats in the Bay of Fundy through dredging could reduce winter flounder populations by altering food availability. Sti.OREtANE MODIFICATION The use of sea walls and bulkheading results in an alteration of intertidal habitat and associated communities (Whitlatch, 1982). Construction of hard surfaces along the coast transforms a soft bottom community to a hard bottom and usually creates a more narrow intertidal and shallow subti-dal zone. There are also cascading effects on marsh and tidal flats due to changes in sediment transport processes and long-shore currents. In the long term, development ofshore'tilhes maC pree\\ the normal migration of salt marshes inland as they respond to rising sea levels. A recent concern has been the effects of shad-ing from docks and piers on eelgrass communities. A recent study carried out in Waquoit Bay on Cape Cod indicated that eegrass plants under docks were lower in a nurnbIr oi growth parameters coin-pared to otutside controls (But-dick and Short. 1995). Shading effects froom docks is also believed to favor algae-dominated communities over eel-grass. Algae-dominated communities do not sup-port the diversity and biomass of fishes that are typical of submerged aquatic vegetation habitats (Deegan et al., 1997). DECTINE IN HABITAT QUAI IIAY The loss of habitat quality or carrying capacity is more subtle than the loss of area. The term hIabi-tat qtmalitv is used to refer to the functional attributes of an area, such as providing food or shelter, needed to support fish and shellfish. Habitat quality is altered by a variety of factors, including sedimentation, nutrients, toxic chemicals, physical disturbance, and colonization by aggres-sive alien species of plants and animals. Sources of these impacts include urban sewer systemt.s, indtms-trial outfalls, ocean dump sites, individual septic systems, storm water runoff, agriculture, fishing gear, and the atmosphere. The degradation of habi-tat quality affects a range of ecological processes: primary and secondary production, trophic dynam-ics, succession, and species diversity. Boston Harbor was an example of how a multi-tude of impacts, including toxic organic contami-nants, heavy metals, nutrient loading, and sedimen-tation, altered the benthic food web. Approximately 60% of the bottom area of Boston Harbor had a benthic invertebrate community that was either moderately or severely impacted by pollution. This trend has been at least partially reversed with the upgrade of the wastweater treatment facility in the late 1990s (Rex et al., 2002).
S iUTlROPitiC( -ON One of the Majoi causcs of habitat decline associated with human activities along the coast is the inc~ense in nutrient loading. esecially nltroeen, In general, tile effects of increased etitrophication are negative. Elevated levels of nutrients runningi into a bay. from lawn feirtiliZers, a'gricuiltural fields. and sewage, stimulate primary production. result-i ng in increased growth of phytoplankton and macroalgae, reduced water clarity, and alteration of the w\\ater chemistry. The iagal species composition changes to a dominance by species that are not readily incorporated into existing trophic structures (Paerl, 1988). Nuisance macroalgae acumirnulate in shaIlow watcrs (I.cc and O1scn, 1985: \\,Valieda et al., 1992) and the abundance of rooted aquatic vegeta-tion declines dtie to shading b\\ attached or floating algae (Orth and.Moore, 1983). If the growth of algae exceeds the ability of higher trophic levels to consume it, the excess bioinass accumulates on the bottom where it is decomposed by microbes. Subsequent effects may be low dissolved oxygen events, changes in the species of plants and animals present, and loss of critical habitats such as sea-grass beds. These effects are likely to affect sniall consullmer organismls such as zooplankton and amphipods, as well as the fishes that depend on these consumers for food. Changes in the food web may alter species composition at the higher trophic levels, from those desirable by humans as food, such as flatfish, to less desirable species such as gelatinous ctenophores or sea-nettles (Purcell, 1992, Caddy, 1993). Low DiSSOLVED OXYGEN Decline and even loss of habitat clue to inade-quate dissolved oxygen (DO) is one of the most severe problems associated with eutrophication of coastal waters. Depletion of some (hypoxia, < 2 rag/L) or all (anoxia) of the oxygen in the water or the sediments causes changes in community com-position and even death of organisms. Although somec degree of oxygen depletion can occur in nat-ural systems, even in offshore basins, oxygen depletion has been exacerbated by increased sewage and increased nutrient inputs resulting from development and agriculture around estuaries. Oxygen is used up by the respiration of bacteria as the excess algae and other organic matter decays. Areas that are particularly prone to hypoxia include coastal ponds, subticlal basins, and salt marsh creeks. Water circulation in coastal ponds is often restricted, 1and inl some ponds may be com-pletely isolated from the sea tor long periods of time. The coastal ponds on the south shore of Cape Cod and Rhode Island are rich habitats for estuar-me fish and shellfish. However, the surrounding watersheds of many ponds have undergone rapid growth in the past thirty years, and they now are routinely lVpoxic in summuier (l.,ee and Olsen, 1985; D'Avanzo and Kremer, 1994). Communities sur-rounding these ponds often propose regular open-ing of these ponds to the sea as a way offrejuve-niating" fish and shellfish habitats. Ihe bottom waters in subtidal basins may be isolated from the well-oxygenated surface waters during periods of stratification in the summer. For example, the dis-solved oxygen levels in Stellwagen Basin occasion-ally drop below 6.0 mgiL when the waters are strat-ified (Kelly, 1993). One approach to understanding the loss of habitat due to low DO is to nap the amount of area in a bay that does not meet minimum DO standards t5 mg/L according to EPA standards, 5.6 mng/L in Massachusetts). Parts of the Inner Harbor in Boston frequently violate the 5 mng/L standard and the Charles River Basin often is completely anoxic because of inputs from combined sewer outflows and altered hydrology (Rex et al., 1992.). In Chesapeake Bay and western Long Island Sound, extensive areas of the bottom often fails to meet minimum DO levels required for survival of fishes and invertebrates (Welsh and Eller, 1991; Breitburg, 1992). Even short episodes Of low DO can have strong effects on fish populations. A severe fish kill in Waquoit Bay was caused by one low DO event which lasted less than 24 hrs (D'Avanzo and Kremer. 1994). Juvenile winter flounder which used the I-lead of the Bay site as a nursery area were killed and washed up on the beach along with shrimp, crabs, and other fish and invertebrates (Figure 5.2). The juvenile winter flounder popula-tion in the anoxic location did not recover, although populations at other sites which did not have a low DO event were unaffected. If the low DO event had been more widespread, it could have caused the failure of an entire year-class for the population
76 LOW DO AT HEAD OF BAY STATION 0.3 E 0.2 0 0.1 0.0 MAY JUNE JULY AUGUST SEPT 1989 Figure5.2. Juvenile winter flounder abundance at three habitats in W\\aquoit.Bay. This graph illustates the effect of a local, 24 hr low. dissolved oxygen event on the abundance of juveniie winter flounder. Juvenile winter flounder at the I-lead of the Bay site were killed by a low dissolved oxygen event that lasted less than 24 hrs (D'Avanzo and Kremer, 1994). PoIplulations at other loca-tions (eelgrass, sand) that did not experience a low DO event were unaffected. of this estuary. even though it lasted less than 24 hours out of the entire year. Low, but not lethal, levels of dissolved oxygen can also lower the growth and survivorship of fish-es and impact shell fish. Growth of juvenile winter liottncder held at oxygen concentrations of 6.7 mg/I was twice that of fish held at 2.2 mgi/L (B ejda et al., 1992). Fish held under conditions of diurnally fluctuating DO also showed growth suppression compared to fish held at high DO levels. Some behaviors of young fish such as moving uIp into the water column and increased swimming activity are also increased Under low DO levels making them more susceptible to Predation (Bejda et al., 1987). Shellfish growing under low oxygen conditions are stressed (see Brousseau. Chapter 6). Not all coastal waters are equally susceptible to low oxygen conditions. In general, low oxygen conditions are rare in surface waters and rare in the winter. Low oxygen is most likely to occur in bot-tom waters at night in the summer because of warm temperatures, high metabolic sediment delnand and water column stratification. Areas that are vertically well mixed and well flushed by the tides, which includes most of the New England coastal enibayinents north of Cape Cod, rarely experience hypoxia. Estuaries in this region may exchange more than 50 percent of their water with well-oxygenated seawater every day. Low DO is not considered a widespread problem in Boston and other urban harbors inorth of Cape Cod, although it can be locally important. lo.sORS tF.;):."RA.55 The alteration and loss of eclgrass habitats due to eutrophication provides a good example of the effect o0f hlalbitat degradation on fish cottt moanities. The high diversity and abundance of invertebrates and fish in eelgrass ecosystems is due to: (l ) increasedl survivorship due to the physical structure of vascular plants that provides protection from predation (Orth et al., 1984; Bell et al., 1987; Pohle et. al.. 1991 ) and (2) greater supply of food (Heck and Crowder, 1991-Deecan et al.. 1993). The fune-tion of> eelgrass and other vegetated habitats in shallow waters parallels that of the cobbles and biogenic structures in deeper offshore waters that are now of such concern because of mobile gear impacts (Anster and i..,angton. 1999). Thus an examination of studies of how the alteration of the structure of eelgrass habitats has affected fish com-mtunities may provide insights for those more off-shore habitats as well. Because eelgrass beds are subtidal, they require relatively clear water so that they have enough light for growth, hence (hey are sensitive to sedi-ment loading and to eutrophication. In the past twenty yeais, eelgrass losses related to declining water quality have been documnented for Southern Massachusetts (Costa, 1988-Short et al.. 1993: Deegan et al., 1993) and Long Island Sound (Rozsa., 1994).1Historical records indicate that eel-grass was once widespread in Boston Harbor, but now only a few limited areas (Hingham Harbor) have suitable light penetration to Support eelgrass (Chandler et al., 1996). For most of the remainder of the New -England coast, there is little docuimen-tation of overall trends in the abundance of.this habitat, although short term fluctuations have been noted (Short et al., 1986). Increased nutrient loading causes declines in the habitat quality of submerged aquatic vegetation and eventually complete loss of large areas of this habi-tat (Costa 1988; Batiuk et al., 1992; Deegan et al., 1993; Short et al., 1993). Eutrophication alters the physical structure of seagrass meadows by decreas-ing shoot density and blade stature, decreasing the size and the depth of beds, and by stimulating the
.1.:15 IF I ff
- kýA '1',. 7 I 77 excessive orowth of macroalgae (Shor t al.,
1993). The initial response of eelgorass to low levels of nitrogcin may be positive where the eelgrass itself is nitrogen-linited (Short, 1987).. Macroalgae and phytoplankton, however, ere able to trInsforn excess nitrogen into growth more rapidly then eel-grass. so they eventually outcom pete and smother the eel,,rass lShort et al., 1993. Another typical consequence of eutrophication within an estuaryI is a geographic shift of eelgrass habitats towards shallower higiih saline areas near the mouth ol the estuary. lelgrass in deeper areas (lie first because the plants are very sensitive to reduced light levels (Dennison, 1987, Costa, 1988). Beds near the head of the estuary are also highly susceptible to the effects of etitrophication because of high nitrogen concentrations resulting from, lie close proximity to runoff from land. Eelgrass is subject tO intense natural population fluctuations which may be exacerbated by eutroph-ication. An epidemic of wasting disease in the early 19'0s wiped out most eelgrass along the entire east coast (Rasmtissen, 1977). Eelgrass recovered to some extent, althotigh it never recolonized some former areas. The disease has periodically recurred in local embayments in more recent years (Dexter. 1985; Short.et al., 1986). Eutrophication may increase the susceptibility of the plants to the wast-ing disease by decreasing the plants ability to resist disease and by restricting the plants distribution within the estuary (Buchsbaum et al., 1990; Short et al., 1993). In the past, low salinity areas of the estuary at the upper reaches of estuaries have been a refuge fr'om the disease during outbreaks. As mentioned above, however, eutrophication tends to be most severe in the low salinity, upper reaches of estuaries. This restricts eelgrass to the more saline areas where it is most susceptible to wasting disease. The replacement of eelgrass by macroalgae in a eutrophic estuary results in a highly modified fish community even before the plants themselves have disappeared (Deegan et al.., 1997). In studies of Waquoit Bay and Buttermilk Bay on Cape Cod, assessments of the relative degradation of eelgrass 'habitats were based on year-round measurements of chemical and physical characteristics (e.g., algal blooms, macroalgae, low DO, high nutrients, dredged channels). Habitats that had moderate water quality had more individuals, more biomass, more species and a higher diversity of fish than WAQUOIT BAY Z 14 E C 0 5 4-3- 2-10 8-6- 4-2- 8 11- -E AI-I 9 C 9 1AR 1989 1990 1988 Figure 5.3. Fish abundance, biomass, number of species and dominance all are lower in low compared to medi-uim quality eelgrass habitats in Waquoit Bay, MA (Deegan ct al.. 1997). Repinhted wiih permission, Estuarine Research Federation. areas with low water quality (Figure 5.3). The number of fish species that use estuaries as a nurs-ery area or spawning location was much lower in areas of poor water quality compared to areas with moderate water quality (Figure 5.4). Fish associated with the benthic zone were more strongly affected than fish associated with the pelagic zone. For example, winter flounder, a benthic species that spawns in the estuary, was one of the first species lost from eelgrass habitats under eutrophic condi-tions. The largest impact of loss of habitat quality on fish community structure was found in the late summer periods as a result of the cumulative effects of habitat degradation (Figures 5.3-5.4).
[i~lI~\\' Number ot Nursery Species 0~ L>1 z z MAR DEC JAN DEC MAR 1988 1989 1990 Number of Estuarine Spawning Species 6 - 1 I I .I 1 I'` l l. l I.I.I I.I. fE Low 5- -aMed C) 4 4)g 3 - 2 - z MAR DEC JAN DEC MAR 1988 1989 .1990 Figure 5.4. Number of species using eelgrass habitats as nursery areas and tile number of species that spawn in estuaries were lower in low compared to mediumn1 quality celgrass habitats in Waquoit Bay, MA\\ (fiom Decean et al., 1993). Many species of fish migrate into estuaries ill the spring and summer as adults to spawn and feed and as juveniles to find protection and ample food before returning to the open ocean as adults. By the end of the summer, when the fish community has experienced the cumulative effects of low oxyvgen, higher mortality due to predation and disrupted food webs, there were fewer species, fewer individ-uals and lower biomass in areas of high anthro-pogenic stress compared to less disturbed areas (Deegan et al., 1997). This result is likely a combi-nation of lowered fish production, higher mortality, and migration away friom degraded habitats. Declines in eelgrass habitats and commercially or recreationally important finfish were apparent in New England over a 30 year time period in Waquoit Bay (Table 5.3). Comparison of the number of species and the percent composition of the catch in eelgrass habitats in Waquoit Bay indicate a sharp decline in the number of species and abundance of recreationally or commercially important species. Table 5.3. Changes ill the fish community coln position of eelgrass habitat in WaCILoit Bay over time. Data are 0ro1mt Deejan el al., 1997 and Curley Ct al. 197 1. Number of Species % Composition Year 1967 1988 1995 1967 1988 1995 Fishery 10 7 3 63 2 9 Forane 14 13 6 3;7 98 81 Total 24 20 9 100 100 100 Species common in commercial and recreational fisheries, such as winter flounder, white hake and pollock declined during this time period. The num-ber of fisheries species declined from 10 to 3, and the percent composition of the catch declined from 63% to 9% between 1967 and 1995. A decline in the lumber of forage species is also apparent which indicates that the loss of fisheries species is probably not due sitllplV to overfishing. The n]u[m11-ber of forage fish declined firom 14 species to 6 species over the same 30 year period. Some small lorage lish. such as sticklebacks and silversides, increased in abundance and forage fish now account for roughly 80% of the catch in eelgrass areas. Direct links between loss of celgrass and loss of commercial catch have been demonstrated in other areas of the world. Jenkins et al. (1993) demonstrated a clear connection between a 70% loss of seagrass and a 40% loss in total commercial fish catch in Western-Port Bay, Australia. The strong, parallel decline in fish catch and seagrass loss occurred in species which were specifically adapted to life in a seagrass habitat. Species with a reduced ecological link did not show a clear paral-lel decline. Along the east coast of the United States. the closest connection between eelgrass and a comner-cially important marine species is not with a fish but is with the bay scallop. The larvae of these bivalves settle on eelgrass blades prior to their transformation into adults (Pohle et al., 1991; Brousseau, Chapter 6). The harvest of bay scallops declined drastically during the wasting disease epi-demic of the 1930s (Thayer et al., 1984). In addi-tion to bay scallops, there is some indication that gadoids in coastal regions make use of eelgrass habitats at certain life stages. Chandler et al. (1996)
": W, 79 found that two to three Year old pollock were caught more often within eelgrass beds then in neighboring., unvegetated habitats in Biostoin Harbor. Pollock also preferred vegetated substrate o\\xer sand in Great South Ba,. Loiing Island (Bricgs and O'Connor, I 171, Tupper and B utilier (1995) reported higher growth rates of age-0 Atlantic cod in celerass comrnpared to sand.y areas, cobble habi-tats, and underwater reefsin Nova Scotia. Survivorship in eelgrass was lower than in. cobble and underw\\.ater reefs hut higher than in sandy. habi-tats. Studies of eelgrass beds alone the Danish coastline in the carI,, 1900s concluded that eclgrass was an important habitat for juvenile cod (Peterson and Boysen-Jensen 1911 ; Peterson, 1918) as have more recent studies in Nova Scotia (Tupper and Butilier, 1995). Most of the fish that currently use eelgrass as a habitat in New England are not directly taken in commercial or recreational fisheries, but are forage fish or prey lfr species taken in lisheries (Deegaln et al., 1997, Heck et al., 1989, 1995). Because much of the current eelgrass habitat is arguably degraded by pollotion to some extent already, establishing a direct link between declines in coin-inercial or recreational iinfish fisheries and loss 61" eelgrass habitat in New England using existing areas will be difficult. Unfortunately, information on fish use of eelgrass areas in New England prior to the 1 930's is lacking, maaking it difficult to estab-lish if eelgrass was an important habitat for fish-eries species prior to the onset of the wasting dis-ease epidemic and habitat degradation. FISt!ING AC'ivIrnEs tISHIIN(i GrEAR The ongoing concern about the impacts of mobile fishing gear on benthic communities in fishing grounds has been reflected in a number of recent symposia, reviews, and edited volumes (e.g., Dorsey and Pederson, 1998; Auster and Langton, 1999; Watling and Norse, 1999; NRC, 2002). The issue is potentially very important since the level of disturbancerepresented by mobile gear is widespread and intense. The development of roller gear through the 1980s and 1990s has allowed trawlers access to rocky and cobble habitats that were formerly inaccessible. As a result, virtually all benthic habitats are nlow potentially, sUsceptible to the effects of mobile gear. We summarize the major cientic issues in toe next ftew Pa!Oai'aphs and suOgest that the reader refer to one of the recent reviews for more details. Mobile fishing gear such as otter trawls, scal-lop rakes, and clam dredges are used in a variety of nearshore and offshore habitats to harv est diemersal and benthic species. These can change the physical habitat and biological structure of ecosystems and therefore have potentially \\yide ranging impacts ott a number of ecological levels. Studies have already documented that mobile gear reduces benthic habi-tat complexity by removing or damtaging the actual physical structure of the seafloor, and causes changes in species composition of infauna, i.e.. smaller invertebrates that live in the upper layers of the sediment and are prey for groundfish (Dayton et al., 1995; Auster and Malatesta, 1995; Auster el al., 1996; Collie et al. 1997; Auster and Langton, 1999: Engel and Kvitek, 1999). Mobile gear may also chan'e surficial sediments and sediment organic matter, thereby affecting the availability of organic matter to microbial Ibod webs (PiIskaln et al., 1999; Schwinghamer et al., 1999). Of major direct concern to commercial fish interests is the potential impact that the loss of benthic structural complexity may have on the survival of juvenile groundfish. From an ecosystems perspective, the simplification of the physical structure in repeatedly trawled areas would likely result in lowered overall biodiversity. The level of trawling in New England waters is intense. Auster et al. (1996) estimated that since 1976, the annual areal extent of trawling on Georges Bank has been equivalent to two to three times its entire bottom area. Some specific loca-tions are trawled as much as 40-50 times per year (A uster and Langton, 1999). Trawling results in a loss of habitat complexity through the removal of both biogenic structures, such as sponges, bryozoans, and shell aggregates and sedimentary features. This is important to fish-eries since physical structure may be critical to the survival and growth of different fish species. Many taxa, especially juvenile fish, exhibit facultative associations with microhabitat features such as bio-genic depressions, shells, burrows, sand wave crests, and even patches of amphipod tubes in low
S r.F1 ; '2 &2 R TIs~ \\j n%1 topographic CnvironIents such as subtidal areas of Massachusetts Bay (Lough et al., 1989; [.angton and Rob nsonr 1990; A uster et al.. 199 1, I 994. 1995, and 1996. Malatesta et al., 1992: Walters and I uanes. 19033-Tupper and Bounihier 1995). Cobble-gravel over sand-mud, for example, is a primary habitat for juvenile lobsters. This habitat may be a bottleneck for the recruitment of earlv benthic phase lobsters, as well as other shelter seeking species such as Jonah (Ca/ice, hore'dis) and rock (Cancer irrorausI crabs (Wahle and Steneck. 1991). Late juvenile silver hake, (Mferluccius Mi/in-earls), showed a positive association with amphi-pod tubes in flat sandy areas (Auster et al., 1994., 1995). Postlarval silver hake mayk occur in patches of dense amphipoCd tube cover to avoid predators and to be near preferred prey (i.e., amphipods and shrimp). Similar associations have been found for Atlantic cod (Gotceitas and Brown 1993) and yel-lowtail flounder (Walsh 1991, 1992). In laboratory studies, Lindholn et al. ( 1999) found that predation on age-0 cod was significantly lower when the bot-torn was covered by emergent epifauna. such as is present in an untrawled area, compared to bare sand. Destruction of benthic organisms. such as amphipods and worms, by trawlintg alters food availability and microtopography which could sub-sequently affect the growth and survival of juvenile fishes. In nearshore habitats, vegetation, such as eel-grass and kelp, and boulders and cobbles provide tile microtopography that provides a refuge and foraging area ibr juvenile fish and macroinverte-brates. In deeper habitats, the microtopography is created by worm and amphipod tubes, sponges, and other biogenic features along wvith the boulders and cobbles. Mobile gear flattens this relief in both areas. Trawl fishing not only changes the physical character of the seafloor, but also increases turbidi-ty and resuspension of bottom sediments (Auster and Langton, 1999; Pilskaln et al., 1999). Sidescan sonar shows that physical disturbance to surficial sediments by trawling, as evidenced by abundant and persistent trawl furrows, is extensive on the seafloor of heavily fished areas within the Gulf of Maine (Jenner et al., 1991; Valentine and Lough, 1991). Trawling generates a plume of suspended sediment which increases turbidity and may alter sediment composition if the finer particles are swept away on water currents. Sonie habitats are 1or1 sensitive 1o the effects of fishing gear than other habitats. In a study of the physiccally stressed intertidal zone of Miinas Basin, the impacts of otter trawling were found to be minor (Brvlinskv et al.. 1994). These coneLfusions. however, cannot be assumed to be true for subtidal habitats with more diverse assemblages of benthic organsniss and lower levels of' natural disturbance (Sainsbury et al., 1993). Daan (1991), on the basis of prodtiucion/biomass ratios, suggested problems mighit be most severe in heavily tished areas, sub-tidal areas, or fbr long-lived org'anmisms. Aister and Langton (1999) presented a concep-tual model in which the impact of mobile gear on habitat complexity increases with fishing effort, but the extent of increase depends on the habitat type. More complex habitats, such as piled boulders and cobbles with epifauna show the steepest decline in habitat complexity with increased fishing effort. Their model predicts that cobbles and gravel with no epitlAuna would show little decrease in habitat complexity with increased fishing effort, since the effect of a trawl there would be to turn over struc-tures, bUt the pie-existing structrures would still be present afterwards. Recently a comparative risk assessment that integrates the size. severitv.sensi-tivity and uncerlainty of the impact of trawling on the seafloor has been developed (NRC, 2002). The impacts of mobile gear are not limited to offshore habitats. Clam harvestino by raking and mechanical harvesting (Cclani kicking")'has a severe and long-lasting effect on seagrass ecosys-tems (Peterson et al., 1987). Seagrass biomass in mechanical harvesting treatments fell by.65% below controls. Recovery did not begin until more than 2 years had passed and seagrass biomass was -35% lower than controls 4 years later. This could have severe impacts on fish and shellfish that depend on seagrass as settling locations or for pro-tection from predators. The extent to which trawling, dredging, and other fishing activities have contributed to the decline in fisheries or would impede recovery of overfished species in New England is still an area of debate among fisheries managers, the industry, and scientists. The evidence at the moment is indi-rect, in that the losses of structural feattires of the benthic community that are known to be important to a number of commercial fish species at some life stages have definitively been observed as a
03S ', N f) I I V F 'NR consequence of mobile fishing oear. A1011-1thou1h 1he evidence does not indicate that tile Current fisheries crisis has been caused in laige lesuIeC by. the habitat effects of mobile Lear. the ma jo concern is with how these habitat ilnipacts 11N al;'ct recov-erv. At the current low population levels of many commercial groundfish it is possible that increased predation on juvenile groundbish in habitat impact-ed by dragging could be hindering recovery. It is logical to assume that an activity carried Out over such a wide area and that impacts juvenile survival will ultimately affect fish populations at low popu-lation levels. It is clearly an area where more research is needed, particuarly on how trawling affects the suirvival ofjuvenile fish and on the impacts and recovery periods of different bottom types undler different intensities of trawling. BY'CATCi-I Discards of bycatch, i.e., non targeted species or undersized individuals, can also have profound effects on fisheries habitat. We cannot do justice to this complex topic here, however it needs to be mentioned. Many individuals discarded as bycatch do not survive after being released. In addition to the obvious direct effects on populations and marine food chains of the loss of a large number of individuals, the disposal of large quantities of dead bycatch may alter the organic matter loading and cause changes in dissolved oxygen profiles and nutrient cycling., HlYDROIOGICAL AUiERAIONS OIF ES'fIuRIES CHIANGES IN FRiWAR INPUiS Fisheri-es yields of coastal species have repeat-edly been correlated with fireshwater inputs (Aleem. 1972; Sutcliffe, 1973; Deegan et al., 1986; Nixon, 1992). Freshwater flow diversion, regtula-tion and alteration by control structures and changes in land use have caused serious damage to estuaries worldwide (Clark and Benson, 198 1, Rozengurt and Hedgepeth, 1989; Hancock, 1993). Virtually every river flowing into Massachusetts and Cape Cod Bays has an altered hydrograph due to control structures or changes in land use (Rebeck Lag 11iiiC aftc.r Lurbainization Las time before -Urbanization Time (hrs) figLure 5.5. Alteration in volume, timing, duration and intensity of freshwater inpuits with increased urbaniza-tion in the watershed (fIoni Dnnne andi leopold 1978). and DiCarlo. 1972). Relation of river r11inotf for the production of hydropower, domestic and indus-trial use. and agriculture reduces the volume and alters the timning of' freshwater delivery to estuaries. The flow of the Ipswich River, for example, is reduced by about half due to water withdrawals for human uses (K. Mackin, lps. Riv. Watershed Assoc., pers. comm.). The type of land use in a watershed is also a strong determinant'of the quan-tity, timing, duration and chemical composition of freshwater inputs to estuaries (Hopkinson and Vallino, 1995). Urbanization, for example, affects the timing and magnitude of river discharge after a rainstorm (FigLire 5.5). Urban areas have large expanses of impervioLis surface, such as roads or parking lots, which causes more water to flow off the land more quickly than if the land were forest or field. Such reductions and alterations of freshwater inputs affect water circulation and the chemical properties of estuaries. Diversion of freshwater increases the salinity of coastal marine ecosystems and can diminish the supply of sediments and nutrients to coastal systems (Boesch et al., 1994). Habitats may change in response to altered hydro-dynamics. Alteration of the natural hydroperiod can affect estuarine circulation on different time and
B 1., I I S 13.ý 1 7 'd niaginitude scales. includinlg short-term (diel) and 'longer term (seasonal or annual) changes. Salinity and sedneimentation rates have a marked effect on the type and rate of wetland habitat present. In addi-nonn, organisms themselves often have specitic Saiin-itv. temrperature or habitat requirements for spawn-ing or successful growth during juvenile stages. Many fish species depend on the developmem of a counter current (low set up by, freshwater dis-charge to enter estuaries as larvae or early juvneniles (e.g., Pearcv. 1962): lownsend and Graham. 198 I Wipplehauser and McClcave, 1987; [ay et al., 1989). Counter current flow is the input of water at the bottom from the coastal ocean to counterbal-ance the outflow of freshwater at the surface. A high frcshwatcr discharge causes a strong saltwater influx which carries many species into estuaries (Kaartvedt and Svendson, 1990). Pearcy (1962) found that larval winter flounder changed their depth distribution between day and night and this, coupled with the conitter-cUTrreit flow, concentrated them in estuaries. As freshwater inputs to estuaries are lessened with increased freshwater withdrawals in the \\wateished, longitudinal and vertical estuarine habitat structure is altered and larval transport can be disrupted (Dadswell et al., 1987). Other examples of New England species likely to be affected by alter-ations in counter current flow are American eel, striped bass, white perch, Atlantic herring, blue, crabs, lobsters, Atlantic menhaden. cunner; toincod and rainbow smelt. DAMtS A.ND ROADYW.A\\S Dam construction on tidal rivers has caused habitat degradation within estuaries. Changes in flow, sediment delivery, salinity. and temperature result in changes in estuarine cominiunity structure, water chemical composition, food webs and loss of f'ershk.ater and estuarine habitats. Withdrawal or diversion of 40'%, of the annual runoff of the Skokomish River (Washington State) has resulted in a 6% loss of total unvegetated flats. more than 40% loss of low iitertidal area, 18% loss of eel-grass area and a reduction in the size of the meso-haline mixing zone (Jay and Simenstad, 1994). One result was a 40% loss of optimal fish habitat between I 885 and 1972 due to changes in sedirnent load and distribution (Figure 5.6). In this case, sed-iment transport was the critical link between upstream alterations and the remote, downstream estuarine consequences. Dams also affect the m igratorv paths of fishes due ditectly' to blocking (Moring, Chapter 3) and also to changes in the dis-tribution. or local extinction, of prey species or alteration of temperature and salinity regimes. Many marshes are fragmented and hydrologi-cally isolated by roads. causeways, railroad beds, and dikes. Restricted water circulation results in declines in primary productivity and fish use of these habitats (Roman et al., 1984; Rozas et al., 1988). MO;SQUTOttCONr ROt. -2
- 4)
MALLW CL Many salt marshes along the east coast of the United States are lined with mosquito control ditch-es. Their effect on fish that use salt marshes is not clear. By increasing the amount of water penetrat-ing into the vegetated surface of the marsh, such channels may increase the use of marsh surfaces at high tide by foraging fish, such as mumimichogs (Rozas et al., 1988). Conversely, negative effects on salt marsh fish would occur where ditches drained salt pannes and fish habitat dried out. POWER PLANTS The impacts of power plants on estuaries and fisheries has been the subject of extensive reviews (e.g., Uziel. 1980; Larsen, 1981; Hall et al.. 1982; Boynton et al., 1982; Summers 1989; Reeves and Figure 5.6. Loss of optimal fish habitat due to diversion of freshwater and resulting alteration of sediment load and hydrology (Jay and Simenstad, 1994). Reprinled iw'ith permission, Estuarine Research Federation.
[ (.\\ r i " \\-i i, us ý ý, \\: i ý r) t ý i,.ý, i,ý ý- i t, \\: S 1) Bunch, 1993)). Power plants can affect fisheries by: I ) altering water circulation patterns by water with-drInwal and changing water temperature. 2) altering estuarine production cycles through changes in water. pertre and circulation patterus. 3t increasitng death, decreasing growth and altering spawning because of elevated water temperatures,
- 4) increasiiw' mortality by direct impingemnent of larvae and juveniles on intake screens, 5) increas-ing mortality and decreasing growth by releasing contaminants such as chlorine, birom inC, copper and zinc, and 6) increasing mortality of fisheries species by direct impingement of their forage species. For example. Summers ('1989) found that striped bass, bluefish and weakfish could experi-ence significant losses (>>25%) to total popuIlation production due to high levels of forage fish entrain-inent by power plants.
There has been interest in using the intense tides in the Bay of Fundv and other macrotidal estuaries throughout the world as a source o0 hydroelectric power. A major issue is the potential affect on fish attempting to pass through the tur-bines. Dadswell and Ruli Son (1994) estimated a mortality of 20-80% of fish, depending on the species. passing through a low head tidal turbine on the Annapolis River estuary in the Bay of Fundy. Dadswell (1996) estimated that the-annual shad spawning run on the Annapolis River has declined by over 50% in a fourteen year period since the installation of the hydroelectric plant despite the absence of local commercial fishing. The mean size, length of males and females, the mean and maximum age of individuals, and the percentage of repeat spawners have all declined in the shad run during the same time period. SEA LEVEL RisE Global change and the rising sea levels could have major impacts on estuarine fish populations and coastal fisheries (Kennedy, 1990; Bigford. 1991). If sea level rises faster than the ability of' salt marsh surfaces to accrete sediment and peat, then a greater amount of the surfaces of salt marsh-es will be regularly flooded during high tides in the future. This would provide increased habitat for estuarine fish if tile marsh maintains its stability. The small change in sea level that has occurred in the last 50 years, howv ever, is not sufticient to have caused the current dramatic declines in fisheries. ExOTtc<; The introduction of exotic species may also have profound effects on habital quality bv ai feet-ing predation and competition interactions. Carlton ( 1993) listed 13 different marine organisms that have been introduced into New England coastal waters since colonial times. inciudino two crabs, a bryozoan, five mollusks, four sea squirts, and one red alga. Some of the exotics, such as the European periwiitkle. Lu.io!r lilo'ecu'., and the green crab. Carci,-ts inaemis, have been with us so long( that few people realize they are not native. Many of these were carried to New England waters as foul-ing organisms on boats or in the ballast water. This is a relatively new area of research, so there are little conclusive data on the ecological impacts of exotics and how they might effect fish and shellfish habitat. Some of the impacts are likely to be quite profound. Green crabs, are voracious predators on soft-shelled clams and newly settled winter flounder, and interfere with -Attempts to transplant eelgrass. The non-native haplotype of Phragiiles acstralis has pushed out native species of salt and brackish marsh plants and may increase the rate of sedimentation in marshes, reducing the amount of intertidal habilat available to marsh fish (Able et al., 2003). Zebra mussels, which have col-onized oligohaline as well as freshwaters in the Hudson River basin (Mills et al., 1996), have had strong effects on freshwater phvtoplankton and zooplankton populations in that river (Caraco et al., 1997). Two CASE-STUIIIES TIIAT CONSIDER BOTll FISiiING AND HABITAT EFFECTS WiNTEt FLOUNDER [N NEW' ENGLAND Winter flounder (Pseudopleuronectes ameri-canius), is one of tile most commercially and recre-ationally important fish species in the northeast and provides one of the best examples of the impor-tance of habitat to fisheries yield (ASMFC, 1992). Many populations spawn in and use estuaries as
S~ 1' 4K hi, 1131L nurscry habitat (t lowe and Coates. 1975: 1lowe ct al.. 1976), It has been the focus of a variety of CnVi ronmeital impanivct Studies Kecause of its CeCo-nomic value and because it shows clear responses to poor 001' alt.i i ii tV (Munche Ian0 and Briggs. 1985; Bejda et al., 1992). Flarl, life stages (eggs. larva and jUveniles) of inshore populations are sus-ceptible to water withdrawal (Crecco and Howell. 1990), toxic substances (Nelson et al., 1991 ) and physical loss or degradation of habitat (Briggs and O'Conner. 1971 ). Habitat degradation has been shown to increase juvenile mortality (Briggs and O'Conner, 1971) and decrease growth (Bejda et al,, 1992: Saucermanl. 1900). Age-I and older fish are also subjected to high levels of recreationa! and fishing mortality (Borenian et al.. 1993). The Fishery Management Plan for inshore stocks of winter flounder provides an analysis of the relative effects of habitat loss versus changes in fishing mortality on fish survival (ASMFC, 1992). Based on the work described below (Boreinan et al., 1993), the plan concludes that a strategy of habitat improvements that would increase juverille sLIrVivorship would result in long term benelits io population success and provide a firmer basis 1or increasingyields in the future than would a strameg,.' based solely on a reduction in fishing mortality. Boreman et al. (1993) compared the relative value of increasing age-0 survival through habitat restoration or decreasing fishing pressure on adult stocks as ways to reverse the trends of decreasing stock declines. They used the eggs-per-recruit (EPR) method which is a way of equating mortality effects on early, life stages of a fish species to sub-sequent loss of fishing opportunity. T1u1s the EPR method can be used to compare changes in poten-tial egg production due to loss ofjuvenile fish because of habitat loss or degradation to losses in egg production due to harvesting of adults. As such, it.gives managers a means to compare poten-tial effects of habitat change with changes in fish-ing mortality. Their analysis based on population characteristics of Cape Cod Bay flounder popula-tions indicates that doubling juvenile survival through habitat restoration yields the same egg pro-duction as reducing fishing mortality by 63%. This result suggests that growth in stock abundance is limited by a carrying capacity bottleneck that occurs sometime before the fish become susceptible to fishing pressure. They also found, however, that very few adult age classes (ages 1-3) contribute to egg, production because fishing mortality was high. [his means that loss ofa single year-class because of disruption of juvCnile habitat could lead to a serious population decline. The combination of habitat limitation and severe overfishing leaves the stock vulnerable to collapse. The best strategy for stock preservation is both habitat improvements and control of fishing pressure. These recommendations apply to inshore stocks of winter flounder. A similar analysis for off-shore populations, such as those on Georges Bank. has not been done and may or may not come to similar conclusions. TiH Nott Nrit t Wrst STit, A us'rti'AIIA Although we currently lack the data to separate fishin, mortality from habitat alteration effects in New England offshore fisherics, examining a simi-lar situation for the North West Shelft region of Australia is instructive. This region faced problems similar to those of our offshore fisheries in New England. Fish species composition was changing from desirable to undesirable species, and total abundance was declino The Northt West Shelf was under intense trawling fishing pressure (Sainsbury et al.. 19093) and its benthic habitat altered. The catch of epibenthic fauna (mostly sponges, alcyoriians and gorgonians) had declined from 500 kg/hr to only a few kg/hr. Little was known about the relationship between the fish stocks and the habitat provided by demersal epibenthic organisms other than that there was a strong correlation between the presence of these. organisms and fish populations. Four research hypotheses were developed which either together or separately could explain the changes: H I. environmentally induced changes independent 0f the fishery, H2. multiple independent responses by fish species to exploitation, H3. alteration of biological interactions due to the fishery, or 1-14. indirect effects of fishing, such as habitat alterations. Each explanation had different management implications. If the main cause for the decline was the loss of epibenthic habitat (hypothesis 4), or trawl-induced changes in competitive/predation
&S A N D) )IAC; R \\D.0 \\1 N'. interactions thyhpothesis 3). then there nioght be scope for expansion of a trap fishery to replace trawling.. OGi tile other hand, if tile historical declines were because these stocks had intrinsically low prodctivcIi ity (hlypothes is 2). thei the onlyt sohu-tion xWas to cut back on all fishing. To clarify these issues. ail adaptive nmanage-ment approach was used. Broad areas ol the NW\\,S were regulated with 2 diff"erent mnanagenment regimes (open to trawling and closed to trawling) tor 5 years arid the fish populations and epibenthos monitored by fishery-independent trawls. Catch rates in the area closed to trawling increased along with the epibenthos, while fish catches and epihen-thos abundance continued to decline in the areas open to trawling. A second area which had initially been open to trawlino was closed to trawling 2 years into the study and catch rates in this area also began to recover. T'hese results show a good correlation between the catch rate and the abundance oftepibenthic organisms, however, it was possible that both the epibenthic organisms and the fish were responding separately to the effects of trawling. To test 1or this. alternate resource dynamic models were developed. Comubining the historical catch and effort data with the experimental results indicated that abundance of the major fish species is limited by the amount of suitable habitat. (epibenthic fauna). The analysis carried out on the NWS illustrates the scope for use of the "adaptive" mianagement approach to evaluat-ing seemingly contradictory explanations to large and complex problems. WiCit NoirriiLAsT' FIstH SPECIES HAVE BEEN AIiFEcTI;) BY HA rI'AT Loss OR DEC RADATION? Because of the complex relationships of indi-vidual species to habitats and the myriad causes of habitat degradation it is difficult to unambiguously establish cause and elffect between habitat declines and fisheries declines. The above example of nearshore populations of winter flounder provides one illustration of a particular population where habitat degradation has affected a fishery. Except for anadromous fish (see Moring, Chapter 3 ) and the decline in bay scallops during the eelgrass wasting disease epidemic in the 1930s (Thayer et al., 1984), there are little data allowing us to unambiguously link habitat changes with regional declines in flSh populakiorIs, since Most fish POPuW lations for which there are adequate data have also been heavily exploited. ().in an embayinei"t level, we know, for example, that loss of eelgrass reduces le ab[:iit\\ of the bha-to su pport hay scallops and Winter flounder. These populations are also under heavy fishing pressure that may have had an equal or greater impact on numbers. The combination of habitat loss and degradation, overfishing, and some natural environinental fluctuations may cause 'Treater declines in a population than any of these r.ctors alone. Some species can use alternate habi-tats, food sources and migration pathways. while others cannot. In addition, different populations of the same species may hive different habitat requLirements. l or exa 0i lp1c, [lie Georges Bank pop-ulation of Winter flounder never comes 'Into any estuary. while other populations are specific to cer-tain estuaries (Howe et al., 1976). With those caveats in mind. there are several predictions one might make i'I habitat losses and degradation were major factors in fisheries declines. Although the discussion of these predic-tions poits to the difficulty of'separating habitat frioin other factors as causirng most fisheries declinies, we 1 hirln it is still instructive. TIli I MOiST,,I \\,"IctjS IOI ((.OSE SPEiCIES W\\VtlOSF HAi\\ITAT HixIA, t31lEN rTIIE MOST DEiRF \\DED. VARIA \\ I'\\tt NS IN H1,,il-\\.iii,IiTA QUAlti\\ ANI) EXTENT SHOUItD BE REFI.ECTED IN FL.UCTUATIONS IN THEI1 FISHI=.I7?0' Anadronious fish are the clearest example of a strong relationship between habitat degradation and population declines (Moring. Chapter 3). Dams. culverts. and cranberry bogs have all been impedi-inents to their passage to spawning areas (Rebeck and DiCarlo, 1972) and erosion due to poor land use practices and euitrophication have degraded their spawning areas. Inshore stocks of winter flounder also show a loss of fisheries yield because of habitat alteration, although the causes vary from estuary to estuary (ASMFC., 1992). Land derived pollhtants tend to decrease in a gradient with distance from shore (Figure 5.7). In sorte estuaries, the loss has been attributed to euItrophication and anoxia; in others, toxic contaminants. The previously cited example of the relationship between bay scallops and eelgrass
86 [)LFG \\ I( S[I ;). I, IS Clostridium peeringens (Normalized to % 4Fines) vs. Distance from Deer Island Point Si
- 51.
020 40 km ,wga,. rie..;, I 40L 19942 6913 1994 1995 i896 .1 1., Yea 1997 M99a 1999 2900 (a) 10-W 70'10-\\\\ 70'?0 \\\\ 42 40" 4010 42)30' 42120' 42°10" Deegan et al. (1 997) on Cape Cod underscore the particular importance of eelgrass habitats in the Northeast to coastal fish and macroinvertebrates in terms of supporting a larger measurable diversity of species than other estuarine habitats. Nonetheless, the impact on linfish fisheries from the eelgrass decline of the 1930s and other, more recent declines has not been demonstrated. This is in part because we lack historical data both on the extent. of these habitats and on abundance of fish within these habitats and because currently few fish species of commercial importance use these habi-tats (Heck et al., 1989; Deegan et al., 1997). Since the present decline in commercial fish species in New England is occurring both near and offshore, nearshore habitat loss is obviously not the only explanation for the decline. The commercial fishery of New England is less dependent on species with a clear ecological dependence on coastal areas than other parts of the country (Nixon, 1980). For example, of the top five impor-tant commercial species of finfish in New England (Atlantic cod, haddock, yellowtail flounder, American plaice and winter flounder), only winter flounder uses estuaries extensively, and even within this species, not all populations use estuaries (ASMFC, 1992). As stressed earlier in this chapter; the most widespread habitat alteration in offshore fishery has been the use of mobile gear. Since all these offshore species are currently at low popula-tion levels due to intensive fishing (Murawski, Chapter 2), any effects of habitat changes from fishing gear have been strongly confounded by fishing mortality. Broad scale environmental changes have occurred on Georges Bank and other offshore regions, but the evidende that they are the primary cause of recent fisheries declines is not compelling. Such environmental changes include recent increases in seawater temperature and the impacts of mobile fishing gear described earlier. If these factors were having a major impact on offshore fisheries populations, then one would, at the very least, expect a decline in the survivorship ofjuve-niles relative to the size of the spawning stock. Such a decline in this ratio could also be caused by other factors, such as survivorship of eggs and 0 year fish prior to recruitment or increases in predator populations, so this is not a conclusive indication, but it should nonetheless occur. Based 7. J (b) Figure 5.7. Distribution of land derived (a) Clostridium (MWRA, 2003) and (b) Dissolved inorganic nitrogen (Libby et al., 2000) from Boston Harbor into Massachusetts Bay. also provides an example of a response of a fish-eries species to habitat degradation and loss. Recent declines in the bay scallop fishery on Long Island have been attributed to the loss of eelgrass as a result of smothering by the brown tide organism (Dennison, 1987). Species, such as bay scallops, that are not flexible and that have very specific requirements for spawning, feeding or migration pathways are most at risk from habitat change. Recent surveys by Heck et al. (1989, 1995) and
ý -,7 -%1ý11A` L! ý AN:rý fýFi;N MIA f i(11: on tire ratio of new recruits to the biomass of-he spawning stock'that spawned the new recruits. there is no evidence 101 Irduced juile SulrViVOr-ship in cod, haddock, and yellowtail flounder (MaCmwsk i. Chapter 2). These species are at his-toric population lows in our region, and it is likely that the magnitude of overfishing in the offshore fisheries overwhelms any effect of habitat alter-ation in New England at this time. LEN IHIC P:i5. SHOULD SI IOW GR"A[IR DECLINES THAN WHOLLY PELAGIC SPI'ECIES Because most habitat alterations have their greatest impact either directly or indirectly on the benthos, another prediction is that benthic species are more likely to be affected by habitat degrada-tion than pelagic species (Caddy, 1993; Deegan et al., 1997). L.ow dissolved oxygen in bottom waters, alteration of benthic substrata, and concentrations of pollutants all should disproportionately impact benthic species. The recent declines in fisheries have, in fact, affected many demersal species dramatically. However some pelagic fish. Atlantic Bluefin Tuna, Atlantic Swordfish. and a number of shark species, are all overexploited and at low population levels along the east coast at present (NMFS. 2001). These are not known to have any benthic stages. Atlantic herring and mackerel, two pelagic species that are not heavily fished now, are presently rela-tively abundant and classified by NMFS as under-exploited (NMFS, 2001). Atlantic herring have demersal eggs and may be subjected to impacts on the benthic comnmunity by mobile fishing gear (Valentine and Lough, 1991), yet they seem to be doing well. THE TIMING OF THE DECLINE IN FISHERIES SHOULD BE RE'LATED TO TIHE TI MING OF HIAB I[AT LOSSES AND DEGRADATION It may be possible to test this hypothesis with nearshore fish that use coastal wetlands and estuar-ies because the periods of some habitat losses are well defined. As described earlier, the filling of coastal wetlands was most intense in the northeast between 1950 and 1970. One would predict that if the loss of coastal wetlands was a major factor in fish declines, then there should have been a larger decline in coastal fish populationsdduring 1950-1970 than in recent ycars when wetlands protection efforts have been stepped tip. There are several reasons wVlhv relationships between wetlands loss and declines in fisheries have been difficult to document even in those regions of the country where the fisheries are com-prised of species that have clear ecological links to coastal wetland habilats. First, we often do not have good documentation on the fishing eflort or landing of inshore fishes most likely to have been affected by these coastal alterations during a rele-vant time period such as during the period of most intensive wetland filling ( 1950- 1970). For example, we have only sporadici niformation on Anierican shad. striped bass and winter flounder landings prior to 1965 (Figule 5.8). Another difficulty is that in the past most estuarine fisheries were not fully exploited, thus, any loss in the total population due to loss of habitat could be made rip in the iisheiy by increasing effort (Houde and Rutherford. 1993; NOAA, 1995). On a national level, most (but not all) estuarine-dependent fisheries in the Uniied States have declined sharply or collapsed, in con-trast to relatively stable catches of estuarine-depen-dent species on a global scale (I loude and Rutherford, 1993). Houde and Ruitherford (1993) attribute overfishing as the major cause of the decline of estuarine fish, with some impacts from habitat alteration and "the vaguely documented but probably real consequences of pollutants and con-taminants." In sum, the "timing hypothesis" is hard to test since there are too many confounding vari-ables-in particular, estuarine fish stocks were overfished at the same time severe habitat alter-ations were occtirring. When the composition of fish comnmunities in coastal areas are considered over long periods of time (> 20 yr) some changes become apparent. In Waquoit Bay, for example, some fish species were 10 to 60 times less abundant in 1967 compared to 1987 while some increased in abundance (Figure 5.9). The differences in the fish cominunity, described earlier in this paper between existing moderate and low quality eelgrass habitats in Waquoit Bay, while consistent and significant, were small compared to such changes seen over a thirty year period in the entire bay (Table 5.3, Deegan et al., 1990). Species common in commercial and
6-AMERICAN SHAD 4-1 t940 1950 1960 1970 1980 1990 STRIPED BASS 0 4' U3 O0... 1940 1950 1960 1970 1920 1990 20-f 15 WINTER FLOUNDER A 5 10] 0' 1940 1950 1960 1970 1980 1990 YEAR FiOure 5.8. Landing statistics for three species, American shad, striped bass and winter flounder, that have a strong ecological co1eCt6i1o tO estuaries and that are Aso11 ilpor-tant in corninercial and recreational fisheries (fhorn Houde and Rutherford. 1993). Note that the landing inltorliation for these species prior to the mid-1960s is very sparse. 1*.'edi*bi1e / h I cri, r-on, 1'u1m17. Rc.e-i h recreational fisheries, such as winter flounder. white hake and pollock declined during this time period, while some small forage Fish. such as stick-lebacks and silversides. increased in abundance. The number of species that declined in abundance exceeded the number of species that increased in abundance across all life-history patterns over the twenty year period (Figure 5. 10). Species that use the estuary as a nursery area were particularly affect-ed with 84% of the species declining in abundance. It is difficult to attribute changes over 20 years in Waquoit Bay to any single cause because many changes occurred simultaneously: land use in the watershed chanred from natural to suburban, nutri-ent loading increased, the open bay' was dredged, and its hvdrology was altered by freshwater control structures and dredging. The decline of eelgrass area to less than 20% of historical levels and the reduced carrying capacity of the remaining habitat as a restlt of these alterations were probably important factors in the change in the fish commu-nity. In addition to these local factors, regional fish-ing pressure has changed the populations of preda-tory fish, such as bluefish, cod, striped bass, and summer flounder, that migrate into estuaries along the coast for part of their life history. T]here are other reasons why there has been no umambiguous "signal" reflected in nearshore fish stocks firomn coastal wetland loss and degradation. It Cunner Pollock Grubby T. Silverside White Hake Winter flounder Mummichog N. Pipefish A. Tomcod Oyster Toadfish A. Silversides Striped Killifish 3 Stickleback Black. Stickleback Bluefish Blue. Herring Rain. Killifish FISH ABUNDANCE 1967 VS 1987 -60 -40 -20 U LU 40 60 LOSS GAIN Fieurre 5.9. Changes in fish Conmunitty coiipos ition and abundance in Waquoit Bay' over a twenty year period (Deegan et al., 1990). Many important commercial and recreationally important species, such as winter flounder, declined in relative abundance, while small forage fish. such as rainwater killitish, have increased in relative tbUd Mice. 20 YEAR CHANGE IN FISH ABUNDANCE 0 20-10-7 o 0 ot _10f -7 20- -20 RESIDENT NURSERY ANADCATAD MARINE ADVENTIOUS TOTAL LIFE HISTORY STRATEGY Figure 5.10. The number of species in each life hisiory category which either declined or gained in abundance from 1967 to 1987 in Waquoit Bay, MA (Deegan, unpublished data). Negative nutmbers indicate the uimn-ber of species that declined in abundance, while positive numbers indicate the number of species that gained in abundance. is possible that despite the past losses of habitat, enough suitable estuarine habitat still remains to sustain populations of estuarine species. In addi-tion, certain essential components of the marsh comrnmunity, such as the mumninichog, Fmndidush. heteroclitis, are sufficiently flexible in their own habitat requirements and tolerant of habitat degra-dation that they can still provide the key links between estuaries and offshore fisheries despite human activities in coastal areas.
"A" L:0ýý AND I! I. iiKALI ý`!-N S 9 Au unwitin ' experivient curently Lmdervav that might test these speculations is related to the tremendous loss ol coastal wetlands in the Mississippi River delta due to land subsidence. In .thits arca. containing roughly one quarter o0 i he country's coastal wetlands, about 57,00( acres of coastal wetlands were replaced by open water Irom 1974-1983 along with an even grealer amount 01 fi'eshwater alluvial wetlands (Tiner, 1991 )..The land in fhe delta is undergoing submergence because the heavily channelized Mississippi River and its tributaries no longer provide the sediment that has historically enabled these wetlands to keep pace with rising sea level (Turner and Rao, 1990). The loss of wetland acreage has not had an inimme-diate impact on such estuarine dependent coirmnier-cial species as brown shrimp, but there is slpecula-tion that the long term consequences could be dis-astrous. once the submerged wetlands remnants completely break tip (B3oesch et al., 1994). Because increased fishing pressure and habitat alterations often occur almost simultaneously, it will always be difficult to completely separate their effects both spatially and ternporally on fisheries. This becomes even more problematic when one source of habitat alteration is the gear used in the fishery. Overfishing and habitat alteration may also act synergistically in contributing to the decline of fisheries. One likely interaction is that overfishing causes the initial collapse of the population and habitat alterations prevent the recovery of the fish-erv even after fishing pressure is reduced. VARIATIONS IN LIFE AMONG DIFFERENT SPECIES HISTORIES (I.E., R-VERSUtS K-SELE"CTED) SHOULD AFFECf[HE DEGREE TO WHICH THE'SE SPECIETS ARE IMPACTED BY HABIIAT AILTERAIMONS One might look at life history characteristics of fish to see if any factors inherent in the fish make their populations more or less susceptible to the impacts of fishing or habitat alterations. Some traits that may be significant include ntumber of young produced, age-specific survival, age at first repro-duction, age-specific fecundity, longevity, and num-ber of different habitats required over a lifespan. Some species, termed r-selected, produce an abun-dance-of young to compensate for fluctuating and unpredictable environments. Juvenile survival is low and the fish typically mature at an early age. Populations levels of K-selected species are con-stinied by a relatively stable enivironmetital carrvilng capacity. K-selected species produce fewer young, butt hi her juveille survi vorship than r-selected species and are slower to reach reproductive age. The relative imloiance of juvenile vCerstis adult mortality should be related to features of reproductive or life history strategy. Juvenile mor-tality is generally related to an aspect of the habitat while adult mortality is often controlled by fishing effort. Schaaf et al. (1993) used life history informa-tion for 12 stocks of fish from the mid Atlantic region to compare the effects of destroying IuveniilC and adult habitat through pollution on stock size. They used estimates of aoe-specific mortality and fecundity in single species computer simulation models to compare the effects on stock size of an increase in mortality at the juvenile stage, such as might be caused by pollution, verstIs increased adult mortality. For example, they found that destroyingt 2% of the estuarine habitat of jivenile Atlantic menhladen could result in a 58% decline in population levels after 10 years. Destroying, the same amount of oceanic adult habitat resulted in only an 8% decline. Variability in juvenile sur-vivorship appears to be quite significant for some stocks, while other stocks were more susceptible to changes in adult mortality. The analysis of Schaaf et al. (1993) which pre-dicted a large decline in long-term harvest of men-haden from a small alteration in juvenile habitat also emphasizes the cumulative impact of small changes in habitat on populations. Their analysis also showed that a severe pollution event (and pre-sumably other forms of habitat degradation) could have a devastating effect if it occurred when the fish were concentrated in their spawning areas. It would be interesting to expand this modeling to include fishing mortality and loss ofjuveniles to bycatch. Most exploited fish species in the northeast are intermediate between r-and K-species and contain elements of both. Groundfish, for example are rela-tively uniform in their life histories, generally maturing between 2 to 3 (gadids) or 3 to 4.(floun-ders) years. Their reproductive and.mortality terms vary from stock to stock. Compared to terrestrial vertebrates, almost all species of fish (and shellfish)
g0 f)BE(iAN & 11CISI(iDfAWON in the northeast produce tremnendous numbers of young and have extremely high juvenile mortality rates and large year to year variations in reproduc-tive success. On the other hand age to first repro-duction differs substantially (2-3 years in Atlantic cod, 7 years in lobsters, 8-10 years in Atlantic bluefin tuna), as does adult survivorship. We pre-dict that populations of rapidly maturing and short-er-lived species are less likely to be influenced by anthropogenic habitat alterations than those that are more K-selected, since rapid growth and maturity should be advantageous in a changing, disturbed environment. In addition, the populations of r-selected species should recover more rapidly fiom. habitat alterations and overfishing, at least in the short term. The analysis remains to be done. IN THFE FUTURE It is clear fiom the above discussions that the links between habitat alteration and loss of fish-eries production can be subtle, diverse and operate on many scales from site-specific to regional. The differences among species in the nature of the rela-tionship between fish and their habitats underscores the difficulty of determining the cause and effect relationships between habitat loss and degradation. and loss of fisheries. It should not be surprising that we can find no unambiguous correlation between a single type of habitat alteration and the loss of a fishery since many habitat alterations have occurred simultaneously. Isolating the impacts of habitat alterations is also confounded by fishing activity and other constraints on fish populations. IMPORTANT RESEARCH QUESTIONS What are the critical ecological processes and habitats that sustain fisheries? For example, are upwellings important in the New England region? What environmental "cues" do fish use to determine migration pathways and spawning locations? How important is regional hydrolo-gy in distributing larvae friom "sources" areas? In estuaries, how important are inputs firom uplands compared to in situ production within the estuary? Are salt marshes and seagrasses critical nursery habitats for fish and shellfish in northern New England as they are in other parts of the country? I'4h1aai' trhe spalial and ltenporal scales of the critical ecological processes? Must we consider processes on the scale of a single salt marsh within an estuary, several salt marshes within a single estuary or a series of estuaries? Is it suf-ficient to understand year-to-year variation or are there longer-term, perhaps decadal trends in weather or river discharge. that we must account for ill oIr management plans? Are there life history bottlenecks? Understanding the sequence of life-history stages that control populations in the absence of harvesting is critical to population manage-ment. Wahle and Steneck (1 991) suggest that cobble habitat is essential for the settling of juvenile lobsters and may be fostering a demo-graphic bottleneck. Ilow many other species of fish have such a critical relationship with a par-ticular habitat type that may be limiting their populations? WI4hat taclors influence the carrying capaciti of/ habitats? For examnple, what role do physical structure and the production of food play in determining how many individuals or species will be found in an area? 1 What lands'cape fiactors control the productivitv anddistribution o/habitats? Understanding why habitats are not uniformly distributed nor uniformly productive among locations would lead to a better understanding of the landscape features that must be preserved to maintain fisheries. For example, are seagrass beds adja-cent to marshes more productive than those in open embayments or those occupying small coves between rocky headlands.? Are offshore biogenic habitats of uniform density more pro-ductive for fish than those that are patchy and scattered? What are the impacts of eutrophication,. con-taminants, and fishing methods on critical eco-logical processes and habitats (i.e. assess ecosystem and habitat integrity) ? We need to understand not only how natural ecosystems and populations function, but also how human
HAIT.AT\\ [LOSS AN\\D f)E7ik.D.AIION 9)1 intervention changes the way ecosystems func-tion. Although changes in water quality as a result of anthropogenic eutrophication are well documented, we know much less about the indirect effects of eutrophication on biological communities. For example., what are the conse-quences to fish of the frequent disturbance of the benthic community by mobile fishing gear? Wf/hat are the separate eipcts of ovetfishing and habitat degradation on populations and ecosystems? Removal of an animal population by fishing and loss of the ability of a habitat to support certain species may have very different implications for the structure and function of ecosystems and the future viability and man-agement of fisheries. Fish that are the targets of fisheries may control important ecosystem pro-cesses by their predation on other animals., behavioral activities such as burrowing, or by providing physical struiture as by-products of their life-history (see Witman and Sebens .1992). Removal of key species can cause the indirect decline of other species. Altering the habitat directly can cause a general decline in the abundance of organisms as well as cause species shifts. IMPORTANT MANAGEMENT QUESTIONs REI.-ATIED TO THiF RESEARCH QUEiSTIONS What are the most important areas of habitat to protect? The Magnuson-Stevens Fisheries Conservation and Management Act (MSFC-MA) of 1996 requires that fisheries managers delineate, protect, and conserve essential fish habitat (EFH). Baseline ecological data must be collected on existing habitats and their asso-ciated fish communities so that managers can determine which habitats should be considered essential to fish, what threats these habitats face, and what level of protection they need. The MSFCMA provides the opportunity to des-ignate a subset of EFH as habitat areas of par-ticular concern (HAPC). These "HAPC's" ate especially critical to some species of fish, vul-nerable to human impacts, and therefore in need of high levels of protection. This may be important if there are multiple choices for a proposed dredge and fill operation or where a specific type of fishing gear is used. fWill a system of marine reserves be a useJliti tool in sustuining/ish p,,pulations? If'so, what are the key characteristics of the habitat that should be protected? A number of scientists have suggested setting tip nonextractive marine reserves as a conservation tool to insure sus-tainable fisheries (see articles in Shackell and Willison 1995). Which species will benefit by having refugia [Vrom direct fishing mortality and friom the indirect effects of fishing gear? What are the habitat characteristics oIf'reatest importance to managed fish antd shellfish and to the integrity of the mainne ecosystem? I--ow will such reserves be manaoed and integ~rated into fisheries management plans? How large do they need to be to be viable? How many differ-ent habitat types should each conlain? H-ow should each be linked to other reserves to make a viable system? WVhat are the trends in various habitats? Is the habitat stable or is it degrading? What natural or anthropogenic factors are responsible for any changes inthe habitat? What type of habi-tat monitoring program is needed to aid in maintaining sustainable fisheries resources? What are the acceptable levels of change in habitat variables? What are the boundaries of acceptable change? For example, how much water can be harvested for offstream use and how much can the seasonality of flow regimes be altered without major impacts on fish com-munities. How often can a benthic conm.unity be trawled before it begins to degrade? What are the quantitative relationships between habitat change and watershed activity? It is important to establish the linkages between watershed activities and fish habitat. Quantitative relationships will have to be estab-lished. For example, what land use practices contribute to sediment runoff and how can land use practices be modified to reduce sediment contribution to an acceptable limit?
- 97)
D1 t Fj C:.' & ý11CI.:I RI.,% 1 7\\1 What are the habitat rehabilitation options? In certain circumstances management actions to rehabilitate degraded habitat may be both desir-able and practical. Managers need data on spe-cific rehabilitation requirements. For example., it may be possible to replant salt marshes, but managers need to know what are the hydrologic, geomorphologica, and production characteris-tics that will make salt marshes productive fish habitats? Cost is another obvious consideration.
SUMMARY
AND CONCLUSIONS
- a.
Over time, the problem for coastal habitats has changed from outright destruction to more sub-tie degradation, such as e utrophication. In off shore habitats, the recent expansion of mobile gear to habitats that were formerly immune to dragging and bottom dredging has exacerbated the impact of fishing activities on habitats and the fisheries they support. The impacts on fish-eries will likely depend on the type and extent of the habitat alteration, the frequency of the disturbance compared to natural changes, the characteristics of the habitat, and the life histo-ry characteristics of the species involved.
- b.
Habitat degradation can drastically alter fish communities. Eutrophication and alteration of freshwater inflows are currently the two most prevalent problems in nearshore habitats. Offshore, substantial changes in the physical and biological structure of habitats as a result of the widespread use of mobile gear have been documented. How these perturbations impact fisheries and the marine food web is still under investigation.
- c.
Winter flounder provides one case where habi-tat degradation is believed to impact certain coastal populations measurably. Toxic pollu-tion, water withdrawals and other forms of habitat degradation reduce the viability of eggs and juveniles. The extent of these impacts varies from place to place.
- d.
Loss and degradation of coastal habitats are probably not the major cause of recent declines in most commercial fish stocks in New England. This is because most of the currently important fisheries are based on offshore populations with no direct ecological connection to nearshore habitats. Habitat alterations in nearshore areas are probably responsible for past and onIgoing declines in some nearshore fisheries.
- e.
The most critical habitat question relating to commercial fish in New England at the moment is how habitat alterations in offshore regions are affecting fish currently at low pop-ulation numbers after years of overfishing. The impacts of widespread and intense disturbance of offishore benthic communities by mobile gear on fish survivorship, particularly juvenile groundfish arid demersal eggs of pelagic species, are potentially significant. Its affect on fish population numbers has not been quantified yet. Such alterations on offshore habitats have not been as significant as overfishing in explaining the current fisheries decline, however, existing data on the impacts of mobile gear suggest that the rate of recovery will be impeded without habitat conservation and managiement.
- f.
A number of modeling studies suggest that even within the context of overfishing, habitat degradation can still have an impact on fish populations. AcKNOVNLELDGI ENTS We thank our colleagues for stimulating and challenging conversations on the relative impor-tance of human versus natural factors controlling populations. Reviews by Peter Auster, Mark Chandler, and William Robinson contributed greatly to this manuscript. This work was supported in part by the Jessie B. Cox Charitable Trust, The National Science Foundation (NSF-OCE 9726921, NSF-DEB 9726862), the Mellon Foundation, the Environmental Protection Agency (R825757 1), and the Massachusetts Bays Program. LITERATURE CITED Able, K.W., S.M. Hagan, and S.A. Browyn. 2003. Mechanisms of marsh habitat alteration due to Phragmites: Response of young of the year mumotichog (Fundulus heteroclitus) to treatment for Phragmnites removal. Estuarie 26:484-494. Aleem, A. A. 1972. Effects of river outflow management on marine life. Mar,.io. 15: 200-208. ASMFC. 1992. Fishery management plan lor inshore stocks of winter flounder. Fisheries Management Report No. 21 of the Atlantic States Marine Fisheries Commission, ASMFC, Washington, DC. 138pp. Auster, P. J. and R.W. Langton. 1999. The effects of fishing on fish habitat. In : L. Benaka (ed.). Fish Habitat: Essential Fish Habitat
iitýPrtilt ti-oss !\\\\t. rii:,;R.\\DTI:.s)i:i 93 iVFH) and Rehabi I itation. American Fisheries Society, B3ethesda, -Maryhand. Auster. I'.1. and R..1. Malatesta. 1995. Assessing the role of non-extractive reserves for enhancing harvested populations in ten-perate and boreal marine ecosystems. In: N. Shackell and J. I-1. M. Williams (eds.). Marine Protected Areas and Sustainable Fisheries: Science and Managemlent of Protected Areas Association. Wolfville, N.S. pp.82-89. Auster, 1..J.. J..t.Malatesta and C. 1_I)onaldson. 1994. Small-scale habitat variability and the distribution of postlarval silver hake. ,krhlccius bilineoris. Proceedings of the G( f lot Maine I labhit Workshop. RARGOM Report Number 94-2:82-86. AustefrI P. J_ R. I. Malatesta and S. C. LaRosa. 1995. Patterns of microhabitat utilization by mobile tauna oil the southern New England (UISA) continental shelf and slope. Marine Ecol Proer. 127:77-88 Auster, I. J., R. I. Malatesia, S. C. LaRosa, R. A Cooper and I_.. I.. Stewart. 1991. Microhabitat utilization by the megafaunal assem-blage at a low relief outer continental shell site - Middle Atlantic Bight, USA. J. NW. Atlan. Fish. Sci. I 5:9-69. Au\\ster, P J., R..I. Malatesta. R. W. I.antgton, I. Watlint" V C. Valentine, C. I.. S. Donaldson, E. W. Langton, A. N. Shepard-and I. G. Babb. 1996. The impacts of mobile fishing gear on seafloor habitats in the Gulf of Maine (Northwest Atlantic). Implications for conservation of fish populations. Rev. in Fisheries Sci 4:1,5 2o2. Baird, S. F. 1873. Report on the condition of the sea fisheries of the South coast of New Fimtland and ut 1871. and 1872. Part I U. S. Comm. of Fish and Fisheries. Washington, DC. Gov. Print. Off. Batiuk, R., R. Orth, K. Moore, W. Dennison, J. Stevenson. I.,. Staver, V. Carter, N. Rybicki, R. I lickman. S. Kollar, S. Bieber and P. Heasly. 1992. Chesapeake Bay submerged aquatic.vegetation habitat recuirements and restoration targets: A technical svnthlesis. Annapolis: US EPA for the Chesapeake Bay Program. December 1992. Be.jda, A.. G.A. Phelan and A. Studholite. 1992. The ell'ect ofdis-solved oxygen on the growth of young-of-the-year winter flounder Plsettdopleironecte.s aiter-icats. Environ. Biol Fishes 34: 21-327. Beida, A., A. Studholne and B. Olla. 1987. Behavioral responses of red hake, Urol)lhyci' chtss, to decreasing concentrations of dis-solved oxygen. Environ. Biol. Fishes. 19:261-268. Bell,.1. D., M. Westoby, and A. S. Steffe. 1987. Fish larval settling in seagrass: Do they discriminate between beds of different leaf density? J. Exp. Mar. Biol. Fcol. 3: 133-144. Bergman, M. J. N., H. W. van der Veer and J_ J. Zijlstra. 1988. Plaice nurseries: Effects on recruitment. J. Fish. Biol. 33A:201-218. Biglbrd, T.E. 1991. Sea level rise, nearshore fisheries and the fishing industry. Coastal Management 19:417-437. Boesch, D. F., M. N. Josselyn, A. J. Mehta,.J. T. Morris, W. K. Nuttle, C. A. Simenstad, and 1). J. P. Swift. 1994. Scientific assessment of coastal wetland loss, restoration, and management in Louisiana. J. Coastal, Res. Special Iss, 20. 103 pp. Boreman,.1., S. J. Correia and D. B. Witherell. 1993. Effects of changes in age-0 survival and fishing mortality on egg production of winter flounder in Cape Cod Bay. Am. Fish. Soc. Syrnp. 14:39-45. Boynton, W. R., W. M. Kemp, C. G. Osborne, E. Spalding, and C. W. Keefe. 1982. Estuarine community dynamics in relation to power olant operations: Benthic process program. University of Maryland, Solornons, MD. 87 pp. NTIS Order No.:PB83-101915. Breitburg, D. 1992. Episodic hypoxia in Chesapeake Bay: interacting effects of recruitment, behavior and physical disturbance. EcoL Mongr. 62:525.546. Briggs, P. T. and J. S. O'Connor. 1971. Comparison of shore-zone fishes over naturally vegetated and sand-filled bottoms in Great South Bay. NY Fish Game J. 18:15.41. Brown. B. 1993. A classification system of marine and estuarine habi-tats in Mainc: An ecosystem appiroach to habitats. Part I: Benthic habitats. Maine Natural Areas Programt Dept. of Fconomic and Co.omunity Development. Augusta. ME. 51 pp. + appendix. Bry insky. N1, J. Gibson and D. C. Gordon Jr. 1994. Impacts of floutn-der trawls ott the intertidal habitat and community of the Minas Basri-Buy of Fundv. Can.1. Fish. Aquat. Sci. 51. Buchlsbatttt R.N. led.) 19920 Tiuntit the tide: Toward a livable coast. in Massachusetts. Massachusetts Audubon Society, Litncoln, MA. 12 ! 1 PIuchsba'um RN.. F. 1. Short and D. 1. Cheney. 1990. Phenolic-nitirogen interactions in eelgrass. Zostera iriinwo L._ Possible implications for wasting disease. Auat. But. 37:291-297. Burdick. D. M. and F. T. Short. 1995. The eflects of boat docks oel eelerass beds in Massachusetts coastal waters. Report to Mass. OfFice of Coastal Zone Management and Waquoit Bay NERR. Caddy, J. F. 1993. loward a comparative evaluation of human impacts on fishery ecosystems of enclosed and semi-enclosed seas. Rev. Fish. Sie. 1:57-95. Caraco, N. F_.1. J. Cole, P. A. Raymond, D. I. Straver, M. L. Pace, S. Findlay, and DT. Fischer. 1997. Zebra mussel invasion in a large turbid river: Phytoplankton response to increased grazing. Ecolog' 78:588-602. Carlton, J T. 1993. A steady stream of invading marine organisms creates ecological roulette in New ss-ngland waters. Fstuarine Rcs. Fed Newsletter 19:11. Chandler. M.. I) Colarusso. and R. BclchsbOaumnt. 1996. A study ofeel-grass beds in Boston Harbor and northern Massachusetts Bays. Proj. report to 0el'l of Research amid Dev'I. i.S. IF1. FP. Narragansett, RI. Clark, J. and N. Benson. 1981. Summary and recommendations of symposium, p 523-528. In: R. 1). Gross and D. L. Williams teds.), Proceedings of a National Symposium on the freshwater inflows to esttiaries. Vol. 11. US Fish and Wildlife Service. FWS/OBS-8 1/04. Collie, J.S., GA. Escariero, and P.C. Valentine. 1997. Effects of bot-tom fishing on the benthic titegaliutna of Georges Bank. Marine Ecol. Pror. Ser. 155:159-172. Costa, J. E. 1988. Felarass in Buzzards Bay Distribution, production, and historical ehantes in abundance. Buzzards Bay Project, EPA. EPA 503/4-88-002. 204p. Crecco, V. and P. Howell. 1990. Potential effects of current larval entrainment mortal itv from the Millstone nuclear power station oil the winter flounder, Pseudoplewuonectes americanus, spawn-Itng population in the Niantic River. Connecticut Department of Environmental Protection, Bureau of Fish and Wildlife, Marine Fisheries Division, Waterford. Cronin, L. E. and A. J. Mansuciti. 1971. The biology of the estuary.
- p. 14-39. In: A symposium on tie biological significance of estu-aries. In: Douglas, P. A. and R. H. Stroud. (eds.)., Sport Fishing Institute Washington, DC.
Curley, JR., R.P. Lawton, J.M. Hickey, and J.D. Fiske. 1971. A study of the marine resources of the Waquoit Bay-Eel Pond Estuary. Monograph Series no. 9. Mass Division of Marine Fisheries. Publ. #1700-6-71-049715. 40 p. Daan, N. 199 1. Theoretical approach to the evaluation of ecosystem effects of fishing in respect of North Sea benthos. Rijksinstituut voor Visserjonderzoek, Ijmtuiden (Netherlands). 9 pp. Dadswell, M. J. 1996. Short-term and long-term impacts of low-head hydroelectric, tidal power generation on estuarine and anadro-mous fish. Abstr. Spring 1996 meeting of the New Engl. Estuarine Res. Soc., Vassar Coll. Poughkeepsie, NY Dadswell, M. J. and R. A. Rulifson. 1994. Macrotidal estuaries: A region of collision between migratory marine animals and tidal power development. Biol. J. Linn. Soc. 51:93-113 Dadswell, M. J., R. J. Klatida, C. M. Moffitt, R. L. Saunders, R. A. Rulifson and J. E. Cooper. (eds.) 1987. Common strategies of anadromous and catadromous fishes. Proceedings of an interna-tional symposium held in Boston, Massachusetts, US.A., March
94 titT(j.5\\ &, r11IrISnAi x 9-13. 1986. American Fisheries Soc. Bethesda, MDID U.S.A. 1:138-150 DahI, "EF. I 996. Wetlands losses in the United States 1781-I9s5i. U.S. Dept. oi Interior, USFWS. Washington. D.C. Repoli to Congress. 21 pp. D'Avanzo, C. and.1 Krcrner. 1904 Diet oxygen dynamics and anoxie eventis in a eutrophic estuary O1 Waqloil Ia'd MaiSsaeliISCtts. EStUarie 11:131-139. Day,., C. A. S. lail. W, Kemp and I.. Yanez-Arancibia. 1989. Estuarine Ecology. Wiley-inter Science, New York. 558 pp. Dayton, P.K., S.F. ThrusLh. ML. Agaidc. and R-1.I lotn in. !995. Environmental effects of marine fishing Aquatic Conservation: Mar Freshlw Ecosvst. 5:205-232. Deegan. L. A. 1993. Nutrient and energy transport between estuaries and coastal marine ecosystems by fish migiation. Can.. Fish Auua ci 50: 74-79. D)eegan, L.,. A, S. Saucerman and D. J. Basler. 1990 Twenty year changes in fishes production in Waquoit Bay related to ecosystem structure and prodLidtivity pp 57-58. In: A. F. Giblin (cd. New England Salt Pond Data Book. Technical Report CRC-90 WHOI. Deegan, I... A., JI.T. Finn, A. Asvazian and C. Ryder. 1993. Feasibility and Apolication of the Index of Biotic Inte-rity to Massachusetts Fstuaries Final project report to Massachiisets Etxectutive Office of Environmental Affairs, 86 pp Deegan, L. I ,... F. Finn. A. vaziani C. Ryder and G BUtiotaccorsi. 1997. D)evelopment and validation of an Estuarine Biotic Integrity iNd; x L u tin's 20:(1 -I - 17. Deegan, L.: A, J. W. Da JIr., A. Yanez-Arancibiu. J. G. Gosselink, G Soberon-Chavez, and P Sanchez-Gil 1986. Relationships among physical characteristics, vegetation distribution and fisheries yield in Gul f'ol \\Iexico estuaries. p 83-100. In. D. A. Woltf ted.). Estuarinc Va'iahilityi Academic Press. NY: Dennison, W. C 1087.7 Eftects of light onl scagrass photosynthesis, grovth and depth distribution. Aquatic,ot. 27:15.26. Dexter, R. W. 1985. Changes in the standing crop of eelgrass, /ostera marina L., at Cape Ann, Massachusetts since the epidemic of 1932. Rhodora. 87:357-366. Dorsey, L. and.1. Pederson (eds.). 1998. Effects of Fishino Gear on the Sea Floor of New Enpland. Conservation Law Foundation, Bostoni. MA. 168 pp. Doyle, 1M. J., \\V W. Morse and A. W Kendall-Jr. 1993. A comparison of larval fish assemblages in the temperate zone of the Northeast Pacific and Northwest Atlantic Oceans. Part I. Larval fish assem-blages and ocean boundaries. Bull. Mar. Sci. 53:588-644. Dunne, T1 and L. Leopold. 1978. Water in environmental planning. W. H. Freeman and Co. NY. Engel, J. and R. Kvitek. 1999. Effects of otter trawling on a benthic community in Monterey Bay National Marine Sanctuarx. Conserv. Biol. 12:1204-1213. Federal Register. 1997. Interim Final Rule to implement the essential fish habitat ([EFt) provisions of the Magnuson-Stevens Fisheries Conservation and Management Act (December 19, 1997), 62:66531-66559 Field, D. W., A. J. Rever. R V. Genovese, and B. D. Shearer. 1991. Coastal wetlands of the United States: an accocuntingl ofa valuti-able natural resource. Special NOAA 20th Anniversary Report, U.S. Dept. of Commerce, NOAA, National. Ocean Service in coop. with U.S. Dept. of Interior, US[WS. 13 pp. Foulis, D.B. and R.W. Tiner. 1994. Wetland Trends for Selected Areas of the Coast of Massachusetts, from Plum Island to Scittuate ( 1977 to 1985-86). National Wetlands Inventory, US Fish and Wildlife Service. Hadley, MA. 14 p. Gotceitas, V. and J. A. Brown. 1993. Substrate selection by juvenile Atlantic cod Gadus morhua: Effects of predation risk. Qeg.kgi. 93:31-37. Govoni, J. J. and C. B. Grimes. 1992. The surface accumulation of larval fishes by hydrodynamic convergence within the Mississippi River plume front. Coot Shel" Res. 12:1265-1276. Govoni. J.,... I Eloss and I). R. Colby. 1989. Ihe spatial distribu-tion of larval fishes about the Mississippi River plume. Ii inot Occaor 34: 178-187. Grities, C. B. and. I 1. Finucanc. 199 1. Spatial distri bution and abun-dance of larval and juvenile fish. chlorophyll and macrozooplank-ton around the Mississippi River discharge pluime, and the role of the plume in fish recruitment. Miar. Ecol. Prof. Ser. 75: 109-119. Slail. I.. W., 1. T. Burton. and L. II. iciden. 1982. Power plant cs ori-nation effects on estuarine and marine organisms. Crit. Rev. Toxicol. 10:27-48 Hancock, D. A. ted.). 1993. Sustainable fisheries throtuih sustainins fish habitat. Proc. Australian Soc. lor Fish Biology Workshop. Victor Harbor. SA Aug 12-13, 1992 Bureau of Resource Sciences Proceedings, Anslrallian Government Publishing Service. Canberra, Australia. Ilankin, A. I.... L. Constantine and S. Bliven. 1985. Barrier beaches salt marshes, and tidal flats. Lloyd Center for Environmental Studies and The Massachusetts Coastal Zone Managetment Program, #! 13899-27-600- 1-85 C.R. Fleck, K. L. and I... Ciosdcri. 1991. Habitat structure and predator-prey interactions in vegetated aquatic systems. In: Bell, S., E. McCoy and 11. Mushinsky. (eds.) Ilabitat Structuire. Chapman and Ilall. L.,ondon. Pp 281-299. Fleck, K. L., Jr.. K. W. Able, M. 1P. Fahay, and C. T. Roman. 1989. Fish and decappod crustaceans ol Cape Cod eelgrass mcado'ss: species composition, seasonal abundance patterns and compari-son with unve scetated sutxstraICs. Estuaries. 12: 59-65. Fleck, K. L.., Ir., K. W. Able, C. T. Roman, and M. 1. Fahay. 1995. Composition, abundance, biomass, and productioni of macrofauna in a New England estuary: Comparisons among eelgrass meadows and other nurs*ry habitats. Estuaries. 18:370-389. I lopkinson. C. S.ý Ir and J. J. Val ino. I 95. The relationships among man's activities in watersheds and estuaries: a model of runoff efflects on patterns ofestuarine community metabolism. .stuarie 18:598-62 1. [loss, D. E. and G. kV IHmaer. 1993. The importance of habitat to early life history ofestuarine dependent fishes Am. Fish. Soc Srn'm. 14:147-158. Iloude, E. and E. Rutherford. 1993. Recent trends it estuarine fish-cries: Predictions of fish production and yield. Estuaries 16:161 - 176. Howe, A. B. and P G Coates. 1975. Winter flounder movements, growth, and mortality off Massachusetts. Trans, Am. Fish. Soc. 104:13-29. Hxowe, A. B., P. Coates and D. Pierce. 1976. Winter flounder estuarine year class abundance, mortality, and recruitment. Trans. Am. Fish. Soc. 105:647-657. Jay, D. A. and C. A. Simenstad. 1994. Downstream effects of water Withdrawal in a small, high-gradient basin: Erosion and deposi-tion ott the Skokomish River Delta. Estuaries. 17:702-715. Jenkins, (3. P, G. J. Edgar, H. May and C. Shaw. 1993. Ecological basis for parallel declines in seagrass habitat and catches of com-mercial fishes in Western Port Pay, Victoria. In: Hancock, D. A. (ed.). Sustainable Fisheries through Sustaining Fish Habitat. Australian Government Publishing Service. Canberra. pp 124-136. Jenner, K., K. W. Strong and P. Pocklington. 1991. A.review of fishery related seabed disturbance in the Scotia-Fundy Region. Contractors report. 46 pp. Kaartvedt, S. and H. Svendson. 1990. Impact of freshwsater runoff on physical oceanography and plankton distribution in a western Norwegian (jord: An experiment with a controlled discharge from a hydroelectric power plant. Estuar. Coast. Smhelf-Sci 31(4):381-395. Kelly, J. 1993. Nutrients and Massachusetts BHy: Ail undate of euitronhication issues. Massachusetts Water Resources Authority. Tech Rep. 93-17. 119 pp. Kennedy, V. S. 1990. Anticipated effects of climate change on estuar-ine and coastal fisheries. Fisheries 16:16-24.
liil l5'TAT [OSSZ A5ND DF.jkjr)AO'sTIN 9S Ianigion, I -W and W F. Robinson. 1990. Faunal IssOCUations Oi scallop grounds in the Western Gulf of Maine. I. Fxp. Mar Biol Ecol 144 157-171. Larsen, f. F. 19SI. Sonic potential cnvironmnental consequences of proposed tidal power developments in the Gulf of Maine and Bay of Funds. Estuaries 4 253. Lee, V and Olsen, S. 1985. Eutrophication and management initia-tives for the control of nutrient inputs to Rhode Island coastal lag'oons Ikstuarin 8:191-202. Libby P.S., C.ID) hunt., WR. Geyer, A.A. Keller, C.A Oviatt and J.T. "furner. 2000. 1999 Ainnual Water Col0urn'1 I %onitori ng Report. Boston: Massachusetts Water Resources Authority. Report 2000-
- 09. 180 p.
Lindholmn, J.B., P..1. Auster. and L.S. Kaufman. 1999. Habitat-mediat-ed survivorship of juvenile (l0-year. Atlantic cod Gadrs morhra. Mar. Ecol. Proar. Ser. 180: 247-256. Lough. R. G. P. C. Valentine, 1). C. Potter. P..1. Auditore, R. G. Bolz. I. D. Nelson, and R. 1. Perry. 1989. Ecology and distribution of juvenile cod and haddock in relation to sediment type and bottom currents on eastern Georges Bank. Mar. Ecol.. Progr. Ser. 56:1-12. MrlatCstua, R J., PV. J uster and 13. P. Carlin. 1992. Analysis.of trarr-sect data for microhabitat correlations and t*unal patchiness. Mar. Ecol. Prog. Ser. 87:189-195. Mayer, L. M., D. F: Schick, R. ,I Findaly and 1). L.. Rice. 1991. Effects ofcotutercial dragging on sedimentary organic matter. Mar Erviron Res 31:249-261. Mills, E. L. D. L Strayer. M. D. Schteurell, and.1 T. Carlton. 1996. Exotic species rr File I ludson River Basin: A histryrr'I of rivasirorrs and introduction,,- stuaries 19:814-823 MIurchelano, R A and R. E. Wolke. 1085. 1.ýpizootic carcinoma in the winter flounder P'seudopleuronecies arnericanus. Science. 228:587-589. MWRA. 2003 Bricting for OMSAP workshop on anbientl monitoring revisions. March 3 I -April I. 2003. Boston: Massachusetts Water Resources Authority. Report ENQUAD ms-083. 96 p. Nelson, D. X., J. F Miller-D Rusanowsky, R. A. Greig, G. R. Sennefelder, R. Mercaldo-Allen, C. Kuropat, E. Gould, F. P. I Thurber. and A. Calabresc. 1991. Comparative reprodctisvc suLc-cess of 'sinter flounder in Long Island Sound: A three year study (biolooy biocltemistry and chemistry). Estuaries. 14:31 S:331 Nixon, S. WA 1980. Bcts\\cen coastal marshes and coastal sisaters-A Iv iew of twenty years of speculation and research on lhe role of salt marshes in estuarine productivity and water ch'emistry in estuarine and wsetland processes. Pp 437-525 in: R. Hlamilton and KB. MacDonald (eds.). Estuarine and Wetland Processes. Plenumn Press. Nixon, S. W. 1992. Quantifying the relationship between nitrogen inputs and the productivity of marine ecosystems. Adv. in Mar. Technol. Conf. 5:57-83. NMFS (National Marine Fisheries Service). 2001. Report to Congress. Status of fisheries 6fthe United States. NMFS. NOAA, Silver Spring, MD. 127 p. NOAA. 1991. Fisheries statistics of the United States. U.S. Dept. of Commerce. Current fisheries statistics 5600-9000. 1971-199 1. NOAA. 1995. Status of the fisher, resources offtthe Northeastern United States fir 1994. NOAA Technical Memorandum. NMFS-NE-108. NRRC (National Research Cotuncil). 2002. Etfects of Trawling and Dredging on Seafloor Habitat. Committee on Ecosystem Effects of Fishing. Ocean Studies Board. National Academy Press. Washington D.C. 136 pp. Odumn, E. P. 1980. The status of three ecosystem level hypotheses regarding salt marsh estuaries, tidal subsidy, outwelling and detri-tus-based food chains. In: V. S. Kennedy (ed.). Estuarine perspec-ti Academic Press. New York. pp.485-495. Orth, R. J. and K. A. Moore. 1983. Chesapeake Bay: An unprecedent-ed decline it submerged aquatic vegetation. Science. 222:51-53. Orth, R. J., K. L. Heck, Jr. and J. van Montfrans. 1984. Faunal rela-tionships in seagrass beds: A review of the intlucnce of plant structrre and prey characteristics. !Estuaries. 7:339-350. Paerl. I1. W. 1988. Nuisance pihytoplankton blooms in coastal, estuar-inc. and inland waters{ Linirol. Occanowr. 33: 823-847. Pearcy, W. G. 1962. Ecology of an estuarine population of winter llounder (Psuedopleronecies atnaerf'tiafs. Bull. Binghari Oceanovir. Coll. 18:39-64. Peters, 1). S. and F. A. Cross. 1991. What is coastal fish habitat? In: Stroud, K. 11. (ed.) Stern gii i the Tide of-Coastal FIish Ilablilat Loss. National Coalition for Marine Conservation, Inc. Savannah, Georgia. Petersen, C. J. G. 1918. The sea bottom and its production of fish food: A sumr ary of 'work done in connection with valuation 0if Danish waters from 1883 to 1917. Rep. Danish Biol. Station. 25:1-82 Petersen, C. J. G. and 1'. Boysen-Jenscn. 1911. Valuation of the sea. I. Animal life of the sea bottom, its food and quantity. Rep. Danish Biol. Station 20: 18 1. Peterson. C. H. L. C. Surnmerson and S. R. Fegley. 1987. Ecological consequences of mechanical harvesting of clams. Fish. Bull. 85:281-298. Pierce. 1). (ed.). 1985. Economic, environmental and management problems facing i'lassachusetts' commercial and recreational marine fisheries. I': Massachusetts MIaine Fisheries. Assessment at Mid-Decade. November 1985. #14226-1500-61-11-85.CR. PiIslalni, C.II.,II.t. Churchill, Iand L. M Mayer I 99 Resispenisron of sedimnnt by bottom trawling in the Gulfof 'Maine and poten-i lia r geochenir crrionsequences. Consery. tiol, r 2:1223-1229. Irhlie, ). G(, V. M. Bricelj, and Z. Garcia-Esquivel. 1991. 'file eel-grass canopy: an above-bottori refuge from benthic predators for juvenile bay scallops.,lngopeclen irrodians. Marr IEcol Prog. Ser. 74 47-59. Purce. J.I E. 1992. F T'hects of preflation by the scyvphoinedusan Chty.saora quinqfecirrha on zooplankton populations in Chesapeake Bay, USA Mar. Ecol. Prog Ser. 87:65.76. Rasmussen, E. 1977. Thie wasting disease ofeelgrass (Zosrtra marina) and its effects on environmental factors and fauna. In: C. P. McCro. and C. I Hlfferich (eds.). Seagrass ecosystems: a scien-tific persnective. Marcel Dekker. New York. pp. 1-52 Rebeck, K. E. and J. S. DiCarlo. 1972. Final completion report. AntdrorlourS fish oroirct. Mass Diiv. Mar. Fish Publ /46496 ( I !5.50-12-72-CR) Reeves, R.R. and Buncl,.I. N. 1993. Forum oni science and resource-related issues in hydroelectric developiett D)ept. of Fisheries and Oecans, Ottawa, Canada. NTIS-accession number MIC 0693 I/I. Rex, A.C., D. WuI, K. Coughlin, M.P. Ball, K.E. Keay, and DI. Taylor. 2002. The state of Boston Harbor: Mapping the Harbor's recovery. Boston: Massachusetts Water Resources Authority. Report 2002-09. 42 p. Rex, A., K. Keay, W. Smith, J. Cura, C. Menzia, M. Steinhaver, and M. Conner. 1992. The state of Boston lHarbor: 199 1. Technical Report 92-3. Mass. Water Resources Authority, Boston, MA. Robinson, W. E., T J. Coffley and P. A. Sullivan. 1990. Newv England Aquarium's ten' year Boston Harbor monitoring prograrn-lirst report. New England Aquar. Edgerton Res. lab., Boston, MA. 108 pp. + append. Roman, C. W. Neiring' and R. Warren. 1984. Salt marsh vegetation change it response to tidal restriction. Environ. Management 8:141-150. Rozsa, R. 1994. Long term decline of Zostera marina in Long Island and Fishers Island Sounds. Connecticut Dept. of Environmental Protection. Unpubl. Report. Rozas, L. P., C. Mclvor, and W. E. Odum. 1988. Intertidal rivulets and creek banks: Corridors between tidal creeks and marshes. Mar. Ecol. Proa. Ser. 47:303-307. Rozengurt, M. and J. Hedgepeth. 1989. The impact of altered river flow on ecosystem of the Caspian Sea. Rev. in Aquat. Set. 1:337-362.
96 ttlttx;.sv &- rti:"istiaiN Ruiz, G. NI. A. ine, atid M. 11. Posey. 1993. Shall ow water as a refuge habitat tor fish and crustaceans in non-vegetated estuaries: an example fhorn Chesapcake Iav. Mar [col Pro, Ser. 99: 1-16. Sainsbury, K. J.. R. A. Campbell and L. W. Whitclaw 1993. Ellrets of-trawling on the marine habitat on tie Northwest Shelf o1 Australia and implications for sustainabl hsheries managemient. In: Hlancock, 1). A. (cd.). Sustainable Fisheries through Sustaining Fish Habitat. Proc. Australian Soc. For Fish Biology Workshop. August 12-13. 1992. Victor I arbor, SA'. ALustralian Government Publishing Service. Canberra. pp 137-145. Saucrman, S. 1990. Movement. distribution and producti. ity 'l post metamor phic winter flounder in different habitat types in Waquoit Ba_,'. M. S. thesis. University 01' Massachusetts at Amherst. Q(0 pp. Saucerman, S. and L. A. Deeganý 1991. Lateral and cross-channel Movement of' voung-oft ihe-vear wsiniter flounder (itstiedopleuroniecles aotericanis) in Waquoit Bay, Massachusetts. Estuaries. 14:440-446. Schaalf W. E., D. S. Pctcis, L. Coston-Clcsmcnts, 1. S, Vaughn and C. WV Krouse. 1993. A simulation model of how life histor' strate-giesi mediate pollution effects on fish populations. Estuaries. 16:697-702. Schwinghamer. P., D.G. Gordon Jr., T. W. Rowell,.J. Prena, D. McKeon, G. Sonnichsen, and J.Y. Guignc. 1999. Ftficts of exper-imental otter trawling on surficial sediment properties of a sandy-bottom ecosystem on the Grand Banks of Newfoundland. Conserv. Biol. 12: 1215-1222. Shackell, N. and.1. I.M. Willison (eds.) 1995. Marine protected areas and sustainable fisheries. Science and Niatagetient of Protccted Areas Assoc., Wolfville, N.S. 300 pp Short, F. "T. 1987. The effiects of sediment nutrients on seagrass growth and morphology. Aquali. Jot. 27:41-57. Short. F. T., A. C. Mathiesoni and J. L. Nelson. 1986. Recurrence of the eelgrass wasting disease at the border of New Hampshire and Maine. Mar. Ecol. Proc, Ser 29:89-92. Short FT., D. NI. Burdick,.. S. Woll'and G. F. Jones. 1993. Fekrass in estuarine research reserves alon' the East Coast ITS A Part 1: Declines from pollution and disease. and Part I1: Management ot celerass meadows. NOAA-Coastal Ocean Program Publ. 107 pp. Sntith. E. M. and P. T. Howell. 1987. The effeicts of bottom trawling on American lobsters, Hloirerus aniericanus, in Long Island Sound. Fish. Bull. 85:737-744. Sutmmers. J.K. 1989. Simulating the effects of power plaint entrain-inent losses on estuarine systems. F;col. Model. 49:31-47. Strtcliffe, W. It, Jr. 1973. Correlations between seasonal river dis-charge and local landings of american lobster and Atlantic halibut in the Gulf of St. Lawrence. J. Fish. Res, Board Can. 30:856-859. Teal., J. and M. Teal. 1969. Life and Death of the Salt Marsh, Ballantine Books, NY Thayer, G., W. Kenworthy and M. Fonseca. 1984. The ecology ofeel-grass meadows of the Atlantic Coast: A community' profile. U.S. Fish Wildl. Ser. FWS/OBS-84/02. 147 pp. Tiner. R. W. 1984. Wetlands of'the United States: Current status and recent trends. U.S. Dept. of Interior, USFWS, National Wetlands Inventory Project. 59 pp. Tiner, R. W. 1991. Recent changes in estuarine wetlands of' the coter-minous United States. Coastal Wetlands, Coastal Zone 91 Conf. ASCE, Long Beach, California: p. 100-109. Tiner, R. W. and W. Ziini, Jr. 1988. Recent wetland trends ii south-eastern Massachusetts. Prepared for USACOE. U.S. Dept. of Interior, USFWS, National Wetlands Inventory Project. 8 pp. Townsend, D. W. 1983. The relations between larval Fishes and zoo-plankton in two inshore areas of the Gull' of Maine. J. Plankton Res, 5:145.173. Townsend, D. W. 1991. Influences of oceanographic processes on the biological productivity of the Gulf of Maine. Rev. Aquat, Sci. 5:211.230. Townsend, D. W., and J. J. Graham. 1981. Growth and age structure of larval Atlantic herring, Clupea harengus harengntr, in the Sheepscot River ELsitary. MI aine. as determined hy dail% growvth increments in otoliths. Fish. Bull 79:123-130. Tupper. NI. and R. G. BotItilier. 1995. Eft'fects ofthabitat on settlement. growth, and postsettlcment survival of Atlantic cod I Gadiis morinla). Can... Fish. Aquatic Sci. 52: 1834-184 1. Turner. R. F. and Y. S. Rao. 1990. Relationships between wetlands i'ragmentation and recent hydrological ciange s in a dcltaic coast. Fslsriei. 13:272-282. FIer.,A. V. 1971a. Periodic and resident conponents in communril tiles of Atlantic fishes. J. Fish Res. Bd. Can. 28:935.956. I\\I er. A. V. 19711Ib. Sirges tf wintter flounder (IPstuedopreo*,uectes americanrrs) into tire intertidal zone. J. Fish. Res. Bd. Can. 28:1727-1732. Uziel, M. S. 1980. Entrainmetint and impingment at cooling water intakes. I. Water. Polhtt. Control. Fed. 52(6): 1616-1630. Valentine, P. C. and R. (3. Lough. 1991.. T'he sea tlotor environment and the fishery of eastern Georges Bank. U.S. Geological Survey Open-File Report 91-439. 25 pp. Valentine. PC. and E. Aý SchmLuck 1994. Geological napping of bio-logical habitats ont Georges Bank and Stellwagen Bank, Gull of Maine Region. Proc. 8th Western Groundfish Conference, Nanaimo, 3rit. Col, Jan 20, 1994 Valiela, I., K. Ioreman, M. LaMontagne, D. 1 lersh, J. Costa, P. Peckol. 1). Dceiio-Anderson, C. DlAvatazo, M. Babione. C. Shami, J. Brawley, and K. Latja. 1992. Coupling watersheds and coastal watels: iSSlrets andt cotiseqC]ptesees of tiutrient loadling it Waquoit Bay, Ma. Estuaries 15:443-457. Wahltc. Rl A. and R. S. Siteneck. 1991. Reciiitneit habitats and hors-cry grounds, ei the American lobster Homarus amtericanus: A demographic bottlutneck? Mar 1:/col. Pror. Ser 69:231-243. Walsh, S. J. 199 1. Contimercial fishing practices on offshore Juventile tlatfish nursery grotuds ott the Grand Bantks of NewfOutndland. Nelt... Sea Res,. 7:423-432. Walsh, S. J. 1992. Factors inrllucneing distribution of jrvenlIC velloiw'- tail flounder (Limandafrtferigineo) oi thie Grand Bank of Newfoundland. Neill. J. Sea Res. 29: 191-203. 'Watling, L. and F. A. Norse (eds.) 1999. Special section Effects of mobile fishing gear ott marine benthos. Conserv. Bio. 12:1178-1240. Watzin, M. C. and J. G. Gosselink. 1992. The fragile flinue Coastal wetlands of, the continental United States. Louisiana Sea Grant College Program. I..S.U. Baton Rouge, IA US Fish and Wildlife Service, Washington DC; and National Oceanic and Atmospheric Admin.. Rockville MI). Walters, C. J. and ti..hanes. 1993. Recruitment limitation as a cotise-quence of natural selection for Use of restricted feeding habitats and predation risk taking by Juvenile fishes. Can. J Fish Aquat. Sci. 50:2058-1070. Welsh, B. L.. and F. C. Filer. 1991. Mechaniisfs controlling summer-time oxygen depletion in Western Long Island Sound. Estuaries. 14:265.278 Whitlatch, R. 1982. The Ecology of New Entland Tidal Flats. FWS/OBS-8 1/01. U.S. Dept. of the Interior. Washington, DC. 125 pp. Wippelhauser, G. S., and J. D. McCleave. 1987. Precision of behavior ofn migrating juvenile American eels (Anguilla rostrata) utilizintg selective tidal stream transport... Cotns. Ciem. 44:80-89. Witman, J. 1. and K. P. Sebens. 1992. Regional variation in fish pre-dation intensity: A historical perspective in the Gulf of Maine. Oceolocia 90:305.315.
INS[ IOR F [I V~A VE NIOI{AIAI.Y AN\\ID I I A R\\ E IN( 97 Chapter VI Effects of Natural Mortality and Harvesting on Inshore Bivalve Population Trends DIANE J. BROUSSEAU Fairfield University Biology Department Fairfield, CT 06430 USA INTRODUCTION The future of the qcuahaung industry of Massachusetts lies in the hands of her cit-izens, since only through public sentiment can suitable laws be obtained for its preservalion. -David L. Belding, 1912 (in Belding, 1930b) The inshore bivalve fishery of New England is focused on three commercial species: the soft-shell clam (= soft clam; Mya arenaria), the quahog (= quahaug, hard-shell clam, or hard clam; Mercenaria mercenaria) and the bay scallop (Argopecten irradians). The soft-shell clam inhab-its intertidal mudflats throughout the region but the primary fishery for this species is centered along the coast of Maine, the North Shore of Massachusetts and in Boston Harbor. The quahog, which inhabits intertidal and shallow subtidal flats, and the bay scallop, which is associated with eel-grass beds (Zostera marina), are predominantly distributed in southern New England (South Shore of Massachusetts including Cape Cod and the Islands, Rhode Island and Connecticut). Since all three species are harvested in Massachusetts, and since Massachusetts fisheries data, albeit limited, are available on each of them, this state will be highlighted throughout this chapter. Historically, Massachusetts has been a major shell-fish producer. During the past fifteen years, (1982-1998) Massachusetts has been the leader nationwide in the production of bay scallops and in .most years is second only to Maine in the produc-tion of soft-shell clams. Combined, the annual landings of quahogs, soft-shell clams and bay scal-lops in Massachusetts have ranged between 3-5 million pounds between 1982 and 1993, valued at between eleven and twenty-one million dollars, ex-vessel price (NOAA, 1999). Commercial landings and average value of the quahog, soft-shell clam and bay scallop fisheries in the U.S. from 1982-1998 are shown in Figure 6.1. Since ex-vessel prices do not reflect costs associated with manag-ing the fishery, such as enforcement, operation of depuration facilities, etc., these values may overes-timate the realized economic value of the resources. Although no complete map of productive shell-fish beds exists, the Massachusetts Geographic Information System (MASS GIS) program in col-laboration with the Department of Marine Fisheries (DMF) is currently mapping locations of potentially productive beds and their public health classifica-tions along the Massachusetts coastline. The map-ping of shellfish management areas and sampling stations has been finished (data available from T. Hoopes, DMF). The completed project will provide needed baseline information against which future assessments of shellfish growing habitat can be compared. Such information will also be useful to managers interested in selecting seeding sites for juvenile shellfish (Parker et al., 1998). There is a growing concern among scientists and managers that the shellfish resources in many
98 (, S 40 H ol,2 U I il Year 30-Soft-shell clam 20 0 Year 20O Bay scallop 20-10- ¢- V 0P Ie 1"" ' -lc Year Figure 6.1. U.S. commercial quahog, soft-shell clam and bay scallop landings in millions of pounds of shucked meats and landed value (millions of dollars), 1982-1998, as reported by the U. S. Dept. of Commerce, NOAA, Fishery Statistics of the United States, http://www.st.nmfs.gov-pls/webpls/MF_ANNU AL_LANDINGS.RESULTS. (black bar =landings; grey bar = value). areas of New England are declining (Rice, 1996). In fact, as early as 1905, reports were issued indi-cated that a decline in shellfish resources was already underway (Kellog, 1905; Belding, 1930a). This decline is reflected in the U.S. commercial landing statistics (Figure 6. 1), especially for soft-shell clam and bay scallop resources, the bulk of which are harvested in New England. Annual catch statistics compiled by Matthiessen (1992) suggest that the landings of quahogs in Massachusetts have steadily declined fr'om the 1950s to the 1990s (Figure 6.2a). Statewide landings of soft-shell clam have remained fairly stable (Figure 6.2b), but land-ings from Buzzards Bay (Alber, 1987) during the period 1955-1985 have steadily decreased. Bay scallop landings from the 1950s to the 1990s show considerable variability, with years of high produc-tion followed by several years of decline (Figure 6.2c), making it difficult to detect a definite trend. A downward trend in these stocks may simply be masked by natural variability. There are a number of possible reasons for declines in landings of bivalve shellfish along the New England coast. One may simply be reduced fishing effort - fewer shellfishermen working coastal areas. This possibiity seems unlikely, how-ever, since on Cape Cod alone, the number of recreational clam permits issued each year has roughly doubled between 1970 and 1990 (Matthiessen, 1992). More likely, the reduced land-ings are the result of reduced availability of the resource due to increased contamination, habitat degradation or loss, and 'overfishing'. The degree to which any or all of these factors contribute to shell-fish decline, however, remains to be assessed. The potential role of contamination are addressed by McDowell (Chapter 7), whereas habitat issues are discussed by Deegan and Buchsbaum (Chapter 5). It is the purpose of this chapter to focus on the role of natural and fishing mortality in the apparent decline of inshore shellfisheries resources in New England, using Massachusetts as the primary example. LIFE HISTORY INFORMATION - FACTORS AFFECTING NATURAL MORTALITY The effective management of any fishery depends on availability of reliable biological infor-mation for the species in question. First, an
3I Quahog Ut CDz_ 0 z I I huh I i, i~ 1. 0) I ýý ýý 0 05 1ý5 Year V) z Z n2! INSIlORE BIVA\\LVE MORTAIITY AND IIARVFSTING 99 understanding of the causes of natural mortality in populations is necessary in order to assess the degree to which overall mortality is due to harvest-ing. Secondly, knowledge of life history informa-tion is essential if harvesting strategies are to be developed and fishery impacts are to be assessed through the use of mathematical models. Among the first accounts of the natural history of the commercially-important inshore bivalves of Massachusetts are the reports of Belding (1930ab,c) published by the Massachusetts Division of Fisheries and Game in the early 1900s and reprinted in 1930 [and again in 2004]. These reports give detailed information on soft-shell clam, quahog and bay scallop life histories and fisheries. Since the publication of those early reports, a considerable body of literature has devel-oped, much of which is of importance in assessing and managing these three species. In some areas, however, critical information is still lacking. SOFT-SHELL CLAM (A'fya arenaria) Mva arenaria reaches sexual maturity in its second year of life (Coe and Turner, 1938; Porter, 1974; Brousseau, 1978, 1987). Gamete production rate varies from year to year and from population to population for reasons yet to be determined (Brousseau and Baglivo, 1988). The time and fre-quency of spawning varies widely in geographically separated populations (Table 6.1). The traditional view of fixed patterns of spawning based on latitu-dinal range is inadequate; habitat-specific exoge-nous factors such as local water temperature and food supply must be considered as well. Settlement of recently-metamorphosed larvae from the plankton, approximately two weeks after fertilization, is the major source of recruitment into the population (since post-larval transport of spat is probably limited). Large fluctuations in yearly recruitment are characteristic of marine organisms with planktotrophic larvae. Larval recruitment, when it occurs, may represent a large proportion of the population, and that year-class may dominate the population for many years to come ("year-class phenomenon"). Recruitment fluctuations from year to year are largely the result of differential mortali-ties which can occur during three critical phases: 1) fertilization, 2) the free-swimming planktonic stage z Z az Year Figure 6.2. Commercial quahog (a), soft-shell clam (b) and bay scallop (c) landings (millions of pounds of shucked meats) in Massachusetts, 195 1-1993. Solid bar = landings as modified from Matthiessen, 1992; gray bar = landings as reported by NMFS, Fisheries Statistics Division (http://www.st.nmfs.gov/ow-commercial/gcrunc-cgi.sh?SELECTIONSTATE=Mas sachusetts&qyear I = 1982&qyear2= 1999).
100 BRoUSSE.., Table 6.1. Duration of the spawning season of MyIva arenaria along the Atlantic coast reported in the literature. (Modified from Brousseau, 1987). STUDY SITE MONTI-H REFERENCE J F M A M J J A S 0 N D Malpeque Bay, Canada St. Andrews, Canada Eastern Maine Boothbay Harbor, ME Robinhood Cove, MA Gloucester, MA Plum Island Sound, MA N. of Cape Cod N. of Boston Ipswich, MA Plymouth, MA Southern Cape Cod Chatham, MA Martha's Vineyard Woods Hole, MA Rhode Island Wickford, RI Stonington, CT New Haven, CT Westport, CT Stafford, 1912 Sullivan, 1948 Stafford, 1912 Battle, 1932 Ropes and Stickney, 1965 Ropes and Stickney, 1965 1951 Welch, 1953 1952 Welch, 1953 1973 Brousseau, 1978 1974 Brousseau, 1978 1975 Brousseau, 1978 Ropes and Stickney, 1965 Belding, 1907 Belding, 1930a Stevenson, 1907 Stevenson, 1907 Belding, 1907 Belding, 1907 Stevenson, 1907 Deevey, 1948 Bumpus, 1898 Mead and Barnes, 1904 1950 Landers, 1954 1951 Landers, 1954 1952 Landers, 1954 1983 Brousseau, 1987 1984 Brousseau, 1987 1985 Brousseau, 1987 Coe and Turner, 1938 1984 Brousseau, 1987 1985 Brousseau, 1987 Belding, 1930a Nelson and Perkins, 1931 Rogers, 1959 1956 Pfitzenmeyer, 1962 1957 Pfitzenmeyer, 1962 1958 Pfitzenmeyer, 1962 1959 Pfitzenmeyer, 1962 New Jersey New Jersey Chesapeake Bay Chesapeake Bay
INSIORE FBVALVE MORTALITY AND IIARVESTING 1 0 I (a) Bain Island, Stoniigton. CT Size Class (ame) (b) Jordan Cove, \\Vaterlord, CT E 04 (c) Long Wharif New I laven, CT Slhe Class (mem) 0( sloe Class (mm) (d) Oyster River, Wesi Haven. CT S (f) Milford Point. Milford, CT Size Class (mm) 0 Si.. Cl..s (040) (g) Old Mill Beach, Westport, CT (hl Saugatuck River, Westport, CT (i) Cove Beach, Stamford, CT E E-Slze Class (0am) Size Class (00) sl Closs (ra) .Figure 6.3. Size frequency distributions of Mya arenaria (soft-shell clam) during the late summer, 1988 for nine pop-ulations in Long Island Sound, (a) Barn Island; Stonington, CT; (b) Jordan Cove, Waterford, CT; (c) Long Wharf, New Haven, CT; (d) Oyster River, West Haven, CT; (e) Gulf Pond, Milford,/CT; (f) Milford Point, Milford, CT; (g) Old Mill Beach, Westport, CT; (h) Saugatuck River, Westport, CT; and (i) Cove Beach, Stamford, CT. and 3) the early post-settlement larval attachment phase. The extent of this early life stage mortality can range from 40 to 100% (Muus, 1973; Gledhill, 1980; Brousseau et al., 1982; Brousseau and Baglivo, 1988; MacKenzie, 1994). As with other newly settled invertebrates (Hunt and Scheibling, 1997), catastrophic post-settlement mortalities of newly-recruited M arenaria are not unusual (Brousseau, unpubl.) and appear to be characteris-tic of some environments. High mortality of spat may result from a number of abiotic factors includ-ing anoxic conditions, unfavorable temperatures, low salinities and the effects of contamination (see McDowell, Chapter 7). Biotic factors such as inter-specific competition (Bradley and Cooke, 1959; Sanders et al., 1962; Moller and Rosenberg, 1983; Andre and Rosenberg, 1991), predation (Kelso, 1979; Wiltse, 1980; Ambrose, 1984; Smith, 1952; Guenther, 1992) and biological disturbance (Dunn et al., 1999) may also contribute significantly to post-settlement mortalities in M arenaria. The
102 BROUSSF.-\\I degree to which these various causes of mortality are responsible for recruitment fluctuations is still largely unknown. In addition to temporal variations, newly-settled
- 1 arenlrwia also show marked spatial variation in recruitment, both within and between populations or population subunits (Snelgrove et al., 1999; Vassiliev et al., 1999). Patterns of recruitment in nine populations/subpopulations of M. arenaria from Long Island Sound during the 1988 late sum-mer spawning period are shown in Figure 6.3.
Spatial variation in spatfall may occur in a wide range of circumstances and depend on such factors as hydrodynamics (Emerson and Grant, 1991), suit-ability of settling substrate and differential survival of post-settlement juveniles. Natural mortality rates, although high for lar-vae and spat, tend to decrease at close to an expo-nential rate with increasing size and age in M. are-naria. (BrOusseau, 1978; Brousseau and Baglivo, 1988). Survivorship schedules fbllow the type Ill survivorship curve of Deevey (1947) - extremely heavy mortality early in life followed by low. roughly constant, mortality rates thereafter. Quantitative inter-populational differences in age-specific survival rates are measurable (Brousseau and Baglivo, 1988), suggesting that within the framework of a general life history strategy, a response to the biotic and abiotic components of the immediate environment is possible. The environmental factors with the greatest effect on the survival of estuarine bivalves, especially the surface-dwelling juveniles, are temperature, salinity, dissolved oxygen, substrate, water move-ment, sediment transport and food availability. Adult M. arenaria, however, typically inhabit the intertidal zone and are adapted to a wide range of fluctuations in water temperature and salinity (Belding, 1930a; Chanley, 1957; Pfitzenmeyer and Drobeck, 1963; Castagna and Chanley, 1973; Shaw and Hammons, 1974). In addition, sediment depth tends to buffer temperature and salinity variations (Sanders et al., 1965; Johnson, 1965, 1967), proba-bly minimizing.the effects of these factors on sur-vival of adult clams. The physical disturbance of clams brought about by activities such as harvest-ing is also a possible factor causing mortalities. Studies have shown that commercial baitworn dig-ging negatively affects the survival of M arenaria by directly damaging shells and by exposing clams to increased risk of predation (Ambrose et al:, 1998). Biotic factors such as competition, predation, disease and parasitism are probably more signifi-cant contributors to natural mortality than abiotic ones, but again the severity of the effect may vary depending on the size (age) of the individual. The failure of the soft-shell clam fishery of New England during the early 1950s was attributed to predation from the green crab (Glude, 1954), but this effect was most likely operating on juvenile clams. Mva arenaria reach a refuge from predation once they attain a certain size or have the ability to burrow to depths beyond the range of the predator (Edwards and Huebner, 1977; Commito, 1983; Smith et al., 1999). Nonetheless, field experiments have demonstrated that one deep-burrowing nemertean, Cerebratulus lacteus, is an important predator of adult soft-shell clams (Rowell and Woo, 1990). Competition for food or space is most likely a substantial cause of mortality only in the small, surface-dwelling clams. On the other hand, para-sites have been reported in both juvenile and adult M. arenaria (Uzmann, 1952; McLaughlin and Faisel, 1997) and two types of neoplasms have been identified. It has been shown that gonadal neoplasms inhibit normal oogenesis and spawning (Barber, 1996), whereas hematopoietic neoplasia, a proliferative disorder characterized by increased numbers of "leukemia-like" cells in tissues and organs (Farley, 1969) has been shown to be a major source of mortality in field populations (Brousseau and Baglivo, 1991; Weinberg et al., 1997). ' The lifespan of M. arenaria has been estimated at 10-12 years in Massachusetts populations (Belding, 1930a) and the oldest individual found in a study of age/growth in Long Island Sound was 11 years of age (Brousseau and Baglivo, 1987). An inverse relationship between growth rate and age has been described for M. arenaria and a general trend of increased growth rates with decreasing latitude exists (Table 6.2), however, geographical considerations alone are poor predictors of growth patterns (Belding, 1930a; Newcombe, 1935; Swan, 1952; Smith et al., 1955; Newell, 1982; Brousseau and Baglivo, 1987) or mean life expectancies. QUAHOG (Mercenaria mercenaria) The youngest age at sexual maturity reported
IN NSIORE BI VAL\\IX NI:MOKI.\\LTTY AN DI) I A RN\\ES H NG; I03) Table 6.2. The time needed for Mwva arenaria to reach harvestable size (51 mm) as reported in the literature (Adapted fiom Brousseau and Baglivo, 1987). Site Latitude Age at Reference 51 mm (yrs) Prince Wi-liam Sound, AL 60'34'N 6-7 Feder and Paul. 1974 Roskilde Fiord, Denmark 55'34'N 6-7 Munch-Petersen, 1973 Lynher River, England 50'23'N 3-4 Warwick and Price, 1975 Econiomy Pt., Nova Scolia 45 20'N 5-6 Newcombe, 1935 (8 ft. above chart datum) St. Andrews, New Brunswick 45 10'N 5 Newcombe, 1935 (8 ft. above chart datum) Clam Cove, New Brunswick 44 45'N 7 Newcombe, 1935 (16 ft. above chart datum) Clam Cove, New Brunswick 44 45'N 5-6 Newcombe, 1935 (8 ft. above chart datum) Sissiboo River, Nova Scotia 44'30'N 5-6 Newcombe, 1935 (8 ft. above chart datum) Bedroom Cove (Georgetown Is.), 43 35'N 5-6 Spear and Glude, 1957 ME Sagadahoc Bay (Georgetown Is.), 43 35'N 3-4 Spear and Glude, 1957 ME Rowley, MA 42 26'N 2-3 Belding, 1930a Quincy, MA 42'09'N 2-3 Turner, 1949 Gloucester, MA 41'39'N 2-3 BrousseaIu, 1979 Monomoy Pt., MA 41°30'N 2 Belding, 1930a West Falmouth, MA 41 30'N 2 Kellogg, 1905 Narragansett Bay, RI 41 24'N 1-2 Mead and Barnes, 1903 Stonington, CT 4 1'20'N 1.5 Brousseau, 1987 Old Mill Bch., Westport, CT 4l°07'N 1.5 Brousseau, 1987 Saugatuck R., Westport, CT 41 06'N 3 Brousseau, 1987 for M. mercenaria is one year of age (Loosanoff, 1937a; Eversole et al., 1980; Bricelj and Malouf, 1980). The spawning time of quahog populations varies with latitude, and the length of the spawning period increases with decreasing latitude (Table 6.3). Local conditions play an important role in the reproduction of this species. Appropriate tempera-ture and food supply is necessary to condition qua-hogs to spawn in the laboratory (Loosanoff and Davis, 1950, 1963; Castagna and Kraeuter, 1981). Gametogenesis.coincides well with phytoplankton abundance (Loosanoff, 1937b; Ansell and Loosmore, 1963) and Kassner and Malouf (1982) have suggested that food availability influences the timing of spawning. Whether or not food or certain chemical constitutents within their food act as a stimulus to trigger spawning in natural populations remains to bedetermined. The major source of M mercenariarecruits into the population is from the settlement of plank-totrophic larvae, and like the soft-shell clam, recruitment of the quahog is sporadic. Unlike the soft-shell clam. (Belding, 1930b; Molter and Rosenberg, 1983), however, there are no reports in the literature of the settlement of extremely large concentrations of spat. Quahogs are seldom found in high enough densities to allow commercial seed harvesting'(Kraeuter and Castagna, 1989). The lar-vae lead a precarious existence at the mercy of both natural enemies and adverse physical conditions. Work to date suggests that predation by organ-isms such as crabs, carnivorous snails, demersal fish and birds is the dominant factor controlling quahog abundance in naturally-occurring sets (Hibbert, 1977; Kraeuter and Castagna, 1985; MacKenzie, 1977; Virnstein, 1977; Bricelj, 1993; Micheli, 1997), but the role of established infauna in limiting M. mercenaria recruitment remains unclear. In spite of a growing number of studies which have demonstrated that established benthos
104 0o,*ss*.S Table 6.3. Spawning period for populations of.\\Iercencaria mercenarca along the east coast of North America based on evidence of gamete maturity and release. (Modified from Eversole, 1989). STUDY SITE TEMP (-C) MONTI-H REFERENCE J F M A M J J A S 0 N D Wellfleet, MA 24 Belding, 1930b Milford, CT 23-25 Loosanoff, 1937b Long Island, NY 20 Kassner and Malouf, 1982 Long Island, NY 20 Delaware Bay, DE 25-27 Keck et al., 1975 Core Sound, NC 27-30 Porter, 1964 N. Santee Bay, SC 20 Manzi et al., 1985 Clark Sound, SC 20-23 Eversole et al., 1980 Wassaw.Sound, GA 22-26 Pline, 1984 Alligator HIbr., FL 16-20 Dalton and Menzel, 1983 Indian R., FL <30 Lesselman et al., 1989 can adversely affect the early recruitment of benth-ic animals (Williams, 1980; Luckenbach, 1984; Andre and Rosenberg, 1991), a study by Ahn et al. (1993) has shown that dense Gemma gemma popuI-lations do not reduce the survival of newly-settled quahogs in a sandy substrate even when food is limited. Similarly, laboratory studies by Zobrist and Coull (1994) have shown that growth and survivor-ship of juvenile clams is not significantly reduced by the presence of meiofauna. Rice et al. (1989) have shown that intensive shellfishing enhances settlement and/or survival of juvenile quahogs, but Whether this is dueto removal of competing adults or to the disturbance of the sediment itself is not known. There is surprisingly little in the way of empirical data available, however, to assess the magnitude o4 the impact of natural sources of mor-tality on larval/juvenile survival. The only pub-lished account is a study of post-settlement survival in a New Jersey population in which a natural mor-tality rate of 75% was reported during the first six months of life (Connel et al., 1981). Life expectancy of adult quahog isnmarkedly higher than that of juveniles (Hibbert, 1977; Connel et al., 1981), and survivorship probably also follows the type III survivorship curve of Deevey (1947). The adult quahog has few natural enemies, few parasites and few pathogens that cause catastrophic mortalities. The occurrence of gonadal neoplasia in M mercenaria has been docu-mented but is rare (Bert et al., 1993), and, in fact, the quahog has been reported to possess an anti-
tumor substance called "niercenene" which may protect the species from cancer (Schmeer. 1964). The recent appearance of QPX, a protistan disease reported to occur in quahogs from Prince Edward Island (Whyte et al., 1994) and Massachusetts (Smolowitz et al., 1998), may represent a signifi-cant threat to survival in juvenile and young adult clams. Mortality within natural populations of Alf. mer-cenaria has been attributed to low salinity by Haven et al. (1975). A mininum salinity tolerance of 10 to 13 PSU was suggested by Castagna and Chanley (1973) and salinity tolerance tests indicate that salinities below 10 PSU would likely result in death during a 10-day exposure period (Winn and Knott, 1992). On the other hand, quahogs appear to be quite tolerant of low temperatures and low lev-els of dissolved oxygen (Winn and Knott, 1992). Mercenaria mercenaria is one of the longest lived inshore bivalves of New England. Belding (1930b) estimated that quahogs live at least 20 to 25 years but Jones et al. (1989) reported two speci-mens from Narragansett Bay that were 40 years of age upon capture. This long lifespan is probably due in part to the clam's hard shell and its ability to close up completely for extended periods of time, excluding all but the most persistent of predators. BAY SCALLOP (Argopecten irradians) Unlike the two other bivalves discussed above, Argopecten irradians is a hermaphroditic bivalve (i.e. possessing both a testes and an ovary when sexually mature). However, only.one type of sex product is usually given off at any one time (Belding, 1930c). It is hypothesized that this non-simultaneous release of gametes helps prevent self-fertilization by individuals within the population. Self fertilization, however, could play a role in the persistence of populations at very low densities. Most scallops only spawn once, during their first year of a two-year lifespan. Such a short life span is unusual among marine bivalves. A life expectancy of 20-30 months has been reported for bay scallops from Massachusetts (Belding, 1930c). The maximum life expectancy of Long Island bay scallops is 22-23 months (Bricelj et al., 1987). In North Carolina, most scallops live only 14 to 18 months (Gutsell, 1930), while in Florida, they live I N S 1 (0lR 13VALVIE %0OIRrA LITY AL AN) IIAR':1ST1 N 105 12 to 18 months (Barber and Blake, 1983). Adult bay scallops experience a period of mass mortality during their second winter and before the start of the second spawning cycle. Belding (1930c) esti-mated that under natural conditions only 20% of the A. irradians reach the two-year mark. The cause of the mortality has been attributed to senes-cence (Belding, 1930c, Bricelj et al., 1987), but the adult bay scallop also has natural enemies. Sea stars and the oyster drill (Urosalpinx cinerea) both prey on adult bay scallops, but their damage is believed to be minimal. Gamete maturation in A. irradians is dependent upon food supply and a certain minimum tempera-ture (Sastry, 1968), but spawning is not restricted to a particular period in the year or to a critical tem-perature (Sastry, 1963). As with soft-shell clams and quahogs, there is considerable geographic dif-ferences in spawning season, with spawning occur-ring later in the year in more southerly populations (Belding, 1930c; Sastry, 1966; Barber and Blake, 1983; Bricelj et al., 1987; Peterson et al., 1989; Tammi et al., 1997; Tettelback.et al., 1999). Bay scallops in Massachusetts commence spawning with increasing temperatures (Belding, 1930c) while those further south spawn with decreasing fall temperatures (Gutsell, 1930; Sastry, 1963). Bay scallop recruitment clearly shows a high degree of variability from year to year (Peterson and Summerson, 1992) which may in large mea-sure be due to variable larval mortality. The initial free-swimming stage is followed by settlement onto elevated surfaces, primarily eelgrass blades (Zostera marina), to which they attach by means of byssal threads. Once settlement occurs, bay scal-lops are vulnerable to predation due to their thin shells, epifaunal habit and inability to maintain pro-longed valve closure. In spite of the fact that eel-grass has been shown to be an effective spatial refuge from some crustacean predators (Pohle et al., 1991), high predatory risk still exists for unattached scallops prior to attainment of a partial size refuge (ca. 40 mm) from most predators. Periodic losses of eelgrass, such as that due to a "wasting disease" in the 1930s, have been disas-trous for the bay scallop industry (Thayer et al., 1984). The occurrence of unusual algal blooms (Aureococcus anophagefferens) has been linked to recruitment failure of bay scallops in LongIsland waters (Siddall and Nelson, 1986; Cosper et al.,
1 06 BROUSSEAU 1987; Tettelbach and Wenczel, 1993). The larvae either starved to death (Gallagher et al., 1989) or encountered suboptimal temperatures for survival due to delayed spawning of the adults brought about by the presence of the algae (Tettelbach and Rhodes, 198 1). An outbreak of the red tide dinoflagellate, Plvchodiscus brevis, has also been linked to the recruitment failure of the bay scallop in North Carolina waters (Summerson and Peterson, 1990). STOCK ASSESSMENT A large part of the difficulty in assessing the role of overfishing on inshore bivalve stocks is the lack of dependable stock assessment data. In Massachusetts, a statewide survey of marine resources, including shellfish, was conducted about 30 years ago by the Division of Marine Fisheries and published between 1965 and 1973 as a mono-graph series (Jerome et al., 1965, 1966, 1967, 1968, 1969; Fiske et al., 1966, 1967,1968; Curley et al., 1970. 1972, 1974. 1975; Chesmore et al., 1971, 1972, 1973; Iwanowicz et al., 1973, 1974). No follow-up survey was ever done, however, so those studies are not useful in assessing trends. The commercial landings statistics cited in the Introduction (Figure 6.1) are simply the annual compilation of the landings statistics reported to the U. S. Department of Commerce by the states. They are of limited use in assessing trends in abun-dance since they are biased by the level of fishing effort and, in the case of sedentary bivalves, the acreage of shellfish beds open to harvest, both of which can vary from year to year. Measures of landings per unit effort (LPUE) are more instruc-tive than landings statistics alone for assessing abundance, and to some degree fishing pressure, since decreases in LPUE with increased fishing effort suggest a population in decline from over-fishing (Gulland, 1974). In order to calculate LPUE, annual estimates of landings as well as a measure of fishing effort are needed. In Massachusetts, landings records (both reports from individual shellfishernen, and consta-ble reports) and licensing information from each town are compiled by the State's Division of Marine Fisheries. These data are currently the only means available to monitor annual changes in shellfish abundance. Reports of yearly catch by individual Table 6.4. Comparison of the shellfish landings (quahog and soft-shell clam) as reported for the years 1990 - 1992 to the Massachusetts Division of Marine Fisheries by shellfishermen and constables. Landings statistics are reported as number of bushels landed. Landings Shellfishermen Constables Soft-shell clams Town: Gloucester 1990 1991 1992 Town: Rowley 1990 1991 1992 Town: Newbury 1990 1991 1992 Town: Essex 1990 1991 1992 Quahogs Town: Dartmouth 1990 1991 1992 Town: New Bedford 1990 1991 1992 Town:, Fairhaven 1990 1991 1992 203 953 1,231 285 281 462 2,857 3,584 5,180 1,352 1,742 1,603 2,000 3,000 4,000 3,800 6,000 6,772 7,879 5,000 5,000 7,610 6,393 2,461 1,822 85 225 13,564 18,951 21,884 2,235 940 465 153 440 234 16,400 8,100 44,200 fishermen, however, may be underestimated. A comparison of the shellfish landings reported by shellfishermen and those reported by constables for seven Massachusetts towns selected at random for
t 0 V) eooo (a) Rowley 600 400 Year t 0 4-t CL 0. Cn S5 INSIIORE BIVALVE MORTALITr AND HIARVFSTING 107 Soo (b) Newb"ury 100. 0 Year ZO-(d) Gloucester 40-40 U 20 Yea r
- Year (c) Quincy 200.e Year CL 0
wO C M0 _j Figure 6.4. Landings per unit effort estimates calculated from soft-shell clam landings for four municipalities, a) Rowley, MA, 1972-1993. No data available for the years 1979, 1980, 1986, 1991 and 1992; b) Newbury, MA, 1972-1993; c) Quincy, MA, 1978-1993. No data available for 1981; d) Gloucester, MA, 1972-1993. No data available for 1975, 1982, and 1989. the years 1990 - 1992 supports this contention. In each town, the size of the.catch reported by the fishermen was consistently lower than that of the warden, in most cases by at least 50% (Table 6.4). As a result, shellfish landings estimates submitted by town constables are generally con-sidered more reliable, but the reliability of these estimates too, can vary from town to town. First, the method of estimation is not standardized among municipalities. In some cases, constable reports are based on the number of diggers, ability of the dig-ger, and a production rate estimate for each flat dug. Such an assessment requires that the constable have an intimate knowledge of the harvesters and the resource harvested and has time allocated to monitor both. In others, the towns rely on a written report from the commercial fisherman coupled with spot checks of catch by the local warden. There are still other towns where the constable simply bases landings estimates on the number of permits issued and the quota allowed, assuming that every fisherman has caught his quota on every day in which fishing can take place. Another difficulty in determining LPUE from Massachusetts landings reports lies with the method of reporting the number of licenses issued. The state requires that only the total numnber of shellfish harvesting permits issued by the town be reported. In some towns more than one species may be fished commercially. For example, many of the towns in Buzzards Bay harvest both quahogs and bay scallops. Therefore, it is impossible in most cases to determine the actual number of shell-fishermen harvesting each resource.
108 BROUISSEAS U Given the shortcomings outlined above, the usefulness of LPUE estimates calculated from Massachusetts DMF shellfish landings reports is limited. However, in the absence of independent stock assessment data, it provides the only source of information currently available to assess trends in abundance of nearshore bivalve stocks. With these serious limitations in mind, the following assessment was made for the soft-shell clam resource in Massachusetts. Estimates of landings per unit effort based on constable "catch" statistics (bushels per year) and the number of commercial shellfish permits issued were calculated for soft-shell clam stocks from the following cities/towns: Rowley, Newbury, Quincy and Gloucester (Figure 6.4). These towns were chosen for three reasons. First, soft-shell clams represent the only commercial bivalve resource in these areas and hence it could be assumed that all reported fishing effort was on this resource. Secondly, it could be assumed that the acreage open to shellfish harvesting has remained unchanged. In fact, increases in the amount of acreage closed to shellfishing on the North Shore were negligible during the 1980s, probably because this area of the coast has not experienced the rapid increase in development and population compared to other parts of Massachusetts during this time period (Buchsbaum, 1992). Thirdly, the number of commercial licenses issued provides a fair estimate of the actual fishing effort applied in any year. Even though the number of recreational permits issued far exceeds commercial ones in many towns, "mess" diggers account for less than 20% of the total catch reported. The absence of any clear trend in the annual landings per unit effort values suggests that soft-shell clam stocks have fluctuated dramatically in abundance during the period of analysis, especially in the towns of Gloucester, Newbury and Rowley (Figures 6.4 a,b,d). In Gloucester, peak periods of abundance occurred during the early 1970s and around 1980, with periods of rapid decline follow-ing. These periods of clam abundance were proba-bly due to an unusually good spatfall which sus-tained the fishery for a few years (R. Knowles, pers. comm.). In Newbury peaks of abundance occurred.in the late 1970s and late 1980s whereas in Rowley soft-shell clam abundance peaked in the mid to late 1970s. o CL (A CD M 0 t .E Cn
- 5 C
'I_j 300 200 100-(a) Quincy mi g I am a* a U 0 60 80 100 120 140 16 Ucenses 0 120 a a (b) Gloucester 100' 80-60" 40 20-06 0 a a a a a a U 0 ,aI a 100 200 300 Licenses Figure 6.5. Relationship between landings per unit effort for soft-shell clam landings and the number of commer-cial licenses issued for two municipalities, a) Quincy, MA, 1978-1993; b) Gloucester, MA, 1972-1993. Of the four data sets, however, the information from Quincy is probably the most reliable (Figure 6.4c). All clams taken legally from Quincy flats must be depurated before being sold. The landings.. data reported by Quincy are the actual number of bushels taken from Quincy flats which passed through the depuration plant in Newburyport. Unless some clams were reaching market illegally, these production figures should account for all the clams taken from the flats in those years. Except for two years of high abundance (1983 and 1992) the reported soft-shell clam production per digger hovered around 75 bushels per year. Again, there is
no clear indication from these data that LPUE has shown a decline over the years studied. The relationship between LPUE and the number of commercial licenses issued for thecities of Gloucester and Quincy is shown in Figure 6.5. While any plot of landings per unit effort against effort must be treated with some reserve, decline in LPUE as fishing effort increases is usually regard-ed as an indication that a stock is overfished (Gulland, 1974). The scatter of points for Gloucester data and the steady clam production from Quincy flats does not support thle contention that resources in these areas are overfished. To some extent this is a self-regulating fishery. Unlike offshore fishermen who must maintain a boat and crew, the capital investment to dig inshore bivalves is small and the diggers will probably choose other employment in years when the resource is not abundant enough to justify the effort. In the absence of truly reliable stock assess-mlent data it can only be said that the available information does not support the belief that soft-shell clam resources of the North Shore are overexploited. The inability to make even these crude assessments for either the quahog or the bay scallop; however, only emphasizes the critical need for more reliable stockassessment information for all commercially fished inshore bivalves. Most importantly, there is a need for accurate landings information. A system that. allows management per-sonnel to determine the volume of shellfish landed on a daily basis should be the goal. Secondly, better ways of estimating fishing effort are needed. A measure of effort such as "hours dug" would pro-vide a more instructive measure of the actual dig-ging pressure on a population. In a study done by Creaser and Packard (1993) information on catch/effort and landings was recorded during all tides fished from a population of soft-shell clam in Machiasport, Maine that had recently been opened for depuration digging. This study could serve as a model to managers from other locales interested in generating reliable catch statistics for their fishery. The city of Gloucester is presently attempting to generate more accurate landings information for clamflats within the city (R. Knowles and D. Sargent, pers. comm.)ý Lack of adequate personnel, however, has limited this effort to flats designated as "management areas". In nearby Salem, a citizen volunteer group (Salem Sound Coastwatch) I NSH(ORE IBIVALVE MORTALIT\\Y AND HA RVESFrING o09 conducted transect surveys to determine soft-shell clam densities in areas of Salem Sound which have been closed to shellfishing for over 30 years (B. Chase, pers. comm.). Sites in Salem Sound, Massachusetts, sampled as part of the DMF's marine resources study in the 1960s (Jerome et al., 1967) have been resampled and may provide some interesting comparative data. However, these efforts are largely local and small in scale. More resources should be made available to municipali-ties so that this type of approach can be extended to all areas in the State which support shellfishing activity. A program similar to the Massachusetts Coastal Commercial Lobster Trap Sampling Program (Estrella and Cadrin, 1992), is needed for inshore bivalve resources so that more accurate trends assessment is possible. FISIERIES ASSESSMENT We have left indcone those things which we ought to have done: And we have done those things which we ought not to have done... -Book of Common Prayer (Anon, 1928) "Overfishing". as it relates to marine resources, can be defined in three ways: (I) as the removal of so many animals from a biological community that ecologically related or dependent species are nega-tively affected; (2) as the removal of so many ani-mals from the population that over time the aver-age size of harvested individuals is reduced dra-matically (growth overfishing); or (3) as a fishing effort so intense that the number of animals har-vested over time declines as a result of lowered reproductive output in the harvested population (recruitment overfishing). The latter definition is operative in much of the finfisheries literature (Gulland, 1974; Beverton and Holt, 1957; Ricker, 1975) and is probably relevant to invertebrate stocks as well. Nevertheless, efforts to predict fish-ing intensities at which this effect will be felt in shellfish stocks have lagged far behind similar efforts for finfish populations. Over the past few decades, however, there has been some progress in
11 0 rOIUSSE[ the knowledge of the dynamics of invertebrate stocks and a resultant interest in the development of methods of assessing and managing these resources. As these approaches have become more refined, an understanding of the life history, envi7 ronment and ecological interactions of the organism has taken on increasing importance. APPLICATION OF FISHERIES MODEI-S Mathematical models have been used by fish-ery scientists in attempts to understand the mecha-nisms driving population dynamics in species. The value of such models to the manager is that they provide a framework in which to study the conse-quences of possible management actions. The three types of models most commonly used in fisheries assessment are: (1) surplus production and yield-per-recruit models (Beverton and Holt, 1957), (2) stock-recruitment models (Ricker, 1975) and (3) matrix population models (Leslie; 1945; 1948). Structural models such as surplus production and yield-per-recruit (Y/R) models can be used to pre-dict changes in yield or Y/R with variations in fish-ing intensity. Stock-recruitment models may be used to predict recruitment levels for a given spawning stock size. Matrix populations models are often used to predict changes in population size based on fixed schedules of vital rates (age or size-specific birth and death rates), i.e. life tables, for the population under study. The success of these models as predictors, however, lies in the degree to which their assumptions are met. While all three types of models have been applied to bivalve popu-lations, the use of more holistic models that inte-grate factors such as natural environmental vari-ability, contamination, habitat impacts, and fishing pressure have yet to be attempted. Matrix population models have been used extensively for analyzing life history tactics in a variety of species (Hartshorn, 1975; Longstaff, 1977; Caswell and Werner, 1978; Enright and Ogden, 1979; Pinero et al., 1984; Levin et al., 1987), and the Leslie matrix model (Leslie, 1945; 1948) in particular, has long been used to estimate population size. These models, however, rely on the availability of age (size) - specific schedules of births and deaths (life tables), information that is not yet available for all the species of bivalves dis-cussed here. Additionally, in their usual form, these models are deterministic. Consequently, they are not entirely appropriate either for shellfish or other marine species in which recruitment ofjuveniles is highly variable from year to year and controlled largely by environmental parameters not yet fully understood. Many extensions to early models of population growth have been developed, including viewing some of the life history parameters as ran-dorm variables and incorporating the effects of har-vesting into the model (Beddington and Taylor, 1973, Rorres and Fair, 1975). The next step is to develop generalized optimal harvesting strategy models for the stochastic case. Limited attempts to incorporate more realistic treatments of recruitment variability into modelling efforts aimed at assessing management strategies have been made.- In a study of yield. sustainability under constant-catch policy and stochastic recruit-ment for the Atlantic surf clam, Slpisula solidissima, Murawski and Idoine (1989) assumed a binary pat-tern of recruitment in which year-class strength is uniformly poor except during relatively infrequent years when exceptionally strong cohorts are recruited. Ripley and Caswell (1996) introduced stochastic recruitment (log normally distributed) to a stage-structured matrix model of clam popula-tions. In a preliminary study of the soft-shell clam, Mva arenaria, using comnputer simulations to esti-mate the mean and range of population size pro-jected over many decades, yearly larval settlement rates were varied randomly while all other vital rates were held fixed (Brousseau et al., unpubl.). The study.found that an adaptive harvesting strate-gy (harvesting intensity is adjusted according to the settlement rates during the recent past) gave rea-sonable yields while protecting the standing stock. The major limitation of all these studies, however, is the inability to verify the range of input parame-ters used. Consequently, it is uncertain whether or not the conclusions reached are directly applicable to populations in the fieldU Better empirical information is needed con-cerning the distribution pattern of settlement rates in shellfish populations. Sensitivity analysis of pop-ulation growth rate to changes in the life history parameters of several species of commercially important shellfish has shown that population growth rate is more sensitive to changes in larval survival/early recruitment than to changes in other life history parameters such as fecundity and adult
survivorship (Bronsseau and Baglivo, 1984; Malinowski and Whitlatch, 1988). Tile importance of this early fluctuating stage in the life history of these species predicates the need to focus more attention on understanding the relationship between stock density and recruitment rates, the long-term pattern of recruitment events and the role of hydro-dynamics in the settlement process in order to improve the usefulness of population models in applications to marine species. Intensive field work focusing on bivalve larval biology in natural sys-tems must be done in spite of its high cost and labor-intensive nature. SUSTAINABILIrY Or TmE BIvALvE FISHiERIES Defining 'overfishing' as that activity which directly leads to declining stocks over time is related to an important finfisheries concept known as max-imum sustainable yield (MSY). As fishing pressure increases more individuals of progressively smaller size are harvested until the decreasing size of the animals results in decreases in total catch size (weight) despite the increased numbers harvested (growth overfishing). The MSY for a commercial finfish species is estimated based on records of commercial catch, size and age of harvested species and annual recruitment variability. Structural models, such as surplus production and yield-per-recruit models developed initially for fin-fish, have been applied to invertebrates in isolated cases (Caddy, 1980), but in general have been of limited usefulness in estimating yields in exploited molluscan stocks. One problem with such models is their dependence on adequate information on the intensity of the fishing effort (see discusssion above). Another problem central to the difficulty in maintaining sustainable shellfisheries is the inabili-ty to define the management unit. The term biolog-ical "stock" has often been used to describe a dis-crete, self-perpetuating population of organisms that share a common gene pool and can be man-aged (Larkin, 1972). The biological stock is now viewed by many in the fisheries community as the management unit. Understanding the genetic struc-ture of an exploited species is the first step in devising management strategies that ensure the long-term survival of a fishery. INS 1; ORE BITVAIVI-MORTALIT TV AND IIAIR\\ IUTIN(I I I Recent developments in molecular techniques have made several types of genetic markers (mito-chondrial DNA, ntclear DNA and allozymes) available for assessing population-level structuring on local and regional geographic scales. These techniques have been widely used in finfisheries research to. estimate intraspecific genetic variation as well as population allocation to mixed-stock fisheries for a number of commercial species including cod (Pogson et al., 1995), bluefin tuna (Grewe et al., 1997), salmon (Scribner et al., 1998) and red mullet (Mamuris et al., 1998). Such stock identification has become a major focus of research efforts aimed at assisting in the formulation of marine finfishery management decisions. Molecular techniques have been used less widely in efforts to delineate shellfish stocks. Information is beginning to emerge for such exploited molluscan species as abalone (Shepherd and Brown, 1993), deep-sea scallops (Wilding et al., 1998) and limpets (Weber et al., 1998) as well as for soft-shell clams (Morgan et al., 1978; Caporale et al., 1997), quahogs (Dillon and Manzi, 1992; Juste, 1992) and bay scallops (Bricelj and Krause, 1992; Wilbur et al., 1999). Large-scale research efforts aimed at defining the stock bound-aries for such widely-distributed species such as M. mercenaria and M. arenaria are needed, however, if effective management of the resource is the goal. For sedentary species, such as bivalves, the dif-ficulty associated with defining the population unit greatly complicates stock assessment calculations. The concept of the metapopulation has been used by population biologists to describe the dynamics of spatially fragmented subunits of species which are linked together by dispersal stages (Hanski and Gilpin, 1991 ). Such analysis could have application in the management d economically important species such as scallops and clams whose stock units may occupy as large an area as a sea, gulf or estuary or as small an area as a single shellfish bed. Decisions regarding management of such resources depend in large part on an understanding of the rel-ative importance of local (demographic) versus regional (recruitment and/or emigration) processes in the overall maintenance of the population unit. In order to assess the relative importance of these factors, however, a clear understanding of stock structure is needed. Related to the difficulty of defining the "unit
I I -) BROU;SFIAI stock" is the difficulty in establishing an overall stock-recruit relationship for sedentary molluscan populations. Stock-recruitment models have been used to predict recruitment levels for a given spawning stock size in various finfish populations (Ricker, 1975). Hancock (1973) reported, however, that there is little evidence to indicate a direct rela-tionship between spawning stock size and recruit-ment in an exploited population of cockle (Cardiurn edule). He concluded that "heavy spatfall may occur in a whole range of circumnstances, including (1) when adult stocks are high or low, (2) when predation has been reduced or (3) when con-ditions for larval survival and settlement are espe-cially good, or any combination of the three." Data on stock and recruitment for most species he dis-cusses are so limited, however, that to generalize for species other than the cockle is unwise. (This difficulty is also described for lobsters by Steneck, Chapter 8). It may simply be that stock-recruitment relationships are masked by the difficulties associ-ated with defining the stock "unit" as discussed above. It is too early to conclude that the size
- and/or demographics of the parent stock has little influence on reproductive success or failure in invertebrate stocks.
CONTAMINANTS AND HABITAT DEGRADATION Increased population pressures during the past twenty-five years leading to overdeveloped shore-line areas and increased threat of bacterial contami-nation have been well documented, especially for the South Shore of Massachusetts (Buchsbaum, 1992; MBP, 1996). This has led to the largest rate of increase in regional shellfish closures in the' State due to contamination by fecal coliform bacte-ria. The North Shore experienced lower closure rates than other regions during this period only because of its long history of shellfish closures due to fecal contamination. As the number of shellfish closures rise, harvesting pressure on remaining beds becomes more intense, increasing chances that overfishing will occur. Increased development brings other changes that influence shellfish habitat and productivity, such as the addition of nutrients and toxicants to estuaries and embayments, alteration or restriction of tidal flow due to roads, bridges, piers and shoreline armament, increased siltation caused by altered land-use practices, and conflicts brought about by the increased use of the nearshore envi-ronment for recreational activities (Deegan and Buchsbaum, Chapter 5; McDowvell, Chapter 7). Eutrophication of estuaries may accompany land-based development (Menzie-Cura, 1996) and may impact shellfish beds by altering the food supply (sometimes increasing shellfish productivity). More often than not however, increased primary produc-tion results in more frequent periods of low dis-solved oxygen through increased respiration of the primary producers and associated community, par-ticularly during warmer weather and overcast days. Sediments may become hypoxic or anoxic, and even shellfish that can survive prolonged periods of low dissolved oxygen (M arenaria, M. mercenaria) can become stressed (Newell and Hidu, 1986). Juveniles are particularly susceptible and may die if dissolved oxygen levels persist for prolonged periods. The presence of increased algal mats or degraded sediments may also interfere with spat settlement. The majority of the contaminant and habitat degradation impacts listed above (and described in more detail by Deegan and Buchsbaum in Chapter 5 and by McDowell in Chapter 7) are rather local-ized, and do not impact the entire metapopulations of soft-shell clams, quahogs and bay scallops uni-form ly. Thus the impacts of contaminants, habitat degradation, and overfishing are difficult to assess not only at the metapopulation level, but also at the local population level because of the broad disper-sive abilities of the planktonic larvae. The analysis presented in this chapter indicates that we are unable to measure and document any significant impacts from the combined stresses of fishing, con-tam ination and habitat destruction. There is no clear evidence of overfishing, at least not for the Massachusetts soft-shell clam fishery. While it is likely that both contaminants and habitat alterations contribute to larval mortality and reduced recruit-ment, the importance of these additional stresses cannot be measured at the present time, especially against the backdrop of extreme interannual vari-ability in recruitment that would be observed in the absence of these anthropogenic stressors.
CONCLUSIONS In view of its importance both to the pub-lic health and to an industry qofsuch mag-nitude I earnestly recommend that a commission he appointed and an appro-priation made to cover a thorough inves-tigation of the entire sub/ecl o] the pollu-tion of our clam flats... -ZA. Howes, 1930 (in Belding, 1930a) This chapter assessed the impact of natural mortality and harvesting pressure on inshore bivalve resources, using data from Massachusetts as the primary example. Based on this review, the only fair conclusion to be drawn is that information currently available for assessment is inadequate to determine whether or not a statewide decline in these commercial stocks has occurred. The LPUE statistics calculated for the soft-shell clam do not support the view that stocks have declined over the past 25 years in the four North Shore communities studied, but that conclusion is based on very limit-ed data. Lack of appropriate data to make even the crudest assessments for quahogs and bay scallops makes it nearly impossible to comment on the sta-tus of those species in the state. The other Northeast states have equally poor data sets or lack critical data entirely on these three species, making defensible stock assessments all but impossible. Added to the difficulty of documenting stock trends is the inherent problem of identifying and assessing natural versus man-made sources of mor-tality. In addition to the various anthropogenic causes of mortality (pollution, habitat destruction, and overharvesting), natural mortality from an adverse environment, predation, competition and disease also contributes to fluctuations in species abundance. The relative importance of each of these factors in the overall picture is far from understood, but almost certainly, no one cause is responsible, nor are the same cause/causes respon-sible for all the species discussed. In clams and scallops, which have vulnerable planktotrophic larval stages, natural mortality is extremely high early in life, resulting in complete INStHORE" BIVAL\\ES MORTALITY AND I).-ARV\\ESTING I 13 recruitment failure during some breeding cycles. It has been suggested (Hancock, 1973) that the rela-tionship between stock and recruitment in such species is so tenuous that the occurrence of a heavy spatfall is equally likely whether adult stocks are high or low, raising a question concerning the benefits of managing or protecting exploited stocks. The perceived absence of a stock-recruitment relationship for invertebrates, however, is more likely the result of a failure to view local clam flats or scallop beds as spatially fragmented subpopula-tions of a larger unit, the dynamics of which can be understood only if all of the subpopulations are considered together. Viewing resource units as part of a series of local subunits which in part, owe their persistence to the dynamics of other local sub-populations, may provide important insights into the management and protection of these areas. It seems undeniable that active harvesting, which removes adults from a population, will ulti-mately affect reproductive output and overall inor-tality levels in a population. Whether or not such alterations lead to reduced productivity over time, however, is less easily determined. No data are available to assess the impact of harvesting fori either the quahog or the bay scallop. Analysis of LPUE versus fishing effort for soft-shell clams indicates that this species is not overfished, but the data on which this analysis is based are question-able at best. The absence of reliable statistics for the assessment of long-term population trends makes it impossible to determine the extent to which reported declines in-these resources are the result of overfishing and not simply the result of natural fluctuations in species abundance. LITERATURE CITED Ahn, l-Y, G. Lopez and R. Malouof 1993. Effects of the gem clam Gemma gem-ma on early post-settlement emigration, growth and survival of the hard clam Mercenaria mercenaria. Mar. Ecol. Pro". Ser. 99:61-70. Alber, M. 1987. Shellfish in Buzzards Bay: A resource assessment. Buzzards Bay Project (BBP-88-02), U. S. EPA, Boston, Mass. 75 p. Ambrose, W. G. Jr. 1984. Influences of predatory polychaetes and epibenthic predators on the structure of a soft-bottom community in a Maine estuary. J. Exp. Mar. Biol. Ecol. 81: 1 15-145. Ambrose, W. G. Jr., M. Dawson, C. Gailey, P. Ledkovsky, S. Leary, B. Tassinari, H. Vogel and C. Wilson. 1998. Effects of baitworm digging on the soft-shell clam, Mya arenaria, Maine: Shell dam-age and exposure on the sediment surface. J. Shel*f Res. 7:1043-1049. Andre, C. and R. Rosenberg. 199 1. Adult-larval interactions in the
114 BROUSSE.AU suspension-cding bivalves Ceroastodernia edu/e and MVijo ore-naria. Mar. Ecol. Pro,. Ser 71 227-234. Anon. 1928. The [ook of Common Prayer. Protestant Episcopal Church Pcnsion Fund. New York. 613 p. Ansell. A. D. and F. A. Loosmnore. 1963. Preliminary observations on the relationship between growth, spawning and condition ii experimental colonies of I euns mercenroiia L. J. Cons. lit. Explor. Mer. 28:285-294. Barber, B. J. 1996. Effects of gonadal neoplasms on oogenesis in soft-shell clam, V/tya aenraria. J. Invert. Pathol. 67:161-168. Barber. B.. and N. J. Blake. 1983. Growth and reproduction of the bay scallop, Argopeccn irradiaons (Lamarck) at its southern dis-tributional limit. J. Fxn. Mar Biol. Fcol. 66:247-256. Battle. H. L. 1932. Rhythmic sexual maturity and spawning of certain bivalve mollusks. Contrib Can Biol. Fish. New Series 7:255-276. Beddington, J. R. & D. B. Taylor. 1973. Optimum age specific har-vesting of a population. Biometrics 29:801 809. Belding, D. L. 1907. Report on the Shellfisherics of Massachusetts. In: Rent. Comm. Fish. and Game 1906, Commonwealth of Massachusetts, Public Doe. 25:46-67. Belding, D. L. 1930a. The soft-shelled clam fishery of Massachusetts. Commonw. Mass. Dep. Conserv., Div. Fish Game, Mar. Fish. Set. 1,65 p. Belding, D. L. 1930b. The quahaui fishery of Massachusetts. Connmonw. Mass. Dep. Conserv., Div. Fish Game, Mar. Fish. Ser. 2,41 p. Belding, D. L. 1930c. The scallop fishery of Massachusetts. Commonw. Mass. Dep. Conserv., Div. Fish Game, Mar. Fish. Ser. 3,51 p. Bert, T M., D. M. Hesselman, W. S. Arnold, W. S. Moore, H. Crurz-Lopez and D. C. Marcelli. 1993. High frequency of gonadal neo-plasia in a hard clam (Atercenaria spp.) hybrid zone. Mar. Biol. 117:97-104. Beverton, R. J. H. and S. J. Holt. 1957. On the dynamics ofexploited fish populations. Fish. Invest. Ministr. Aric. Fish. Food, Ser. 2, 19:1-533. Bradley, W. H. and R. Cooke. 1959. Living and ancient populations of the clam Geniria gemnina in a Maine coastal tidal flat. Fish. Bull. U. S. 58:304-334. Bricelj, V. M. 1993. Aspects of the biology of the northern quahog, Mevrcaita inmercearia, with emphasis on growth and asryvival during early life history. In: M. A. Rice and D.Grossman-Garber (eds.). Proc. 2nd R.I. Shellf. Industry Conf, Narragansett, R. I., Aug. 4, 1992, R. I. SeaGrant, Narragansett, R. 1. (USA) 1993, pp. 29-48. Bricelj, V. M. and M. K. Krause. 1992. Resource allocation and popu-lation genetics of the bay scallop Argopecten irradians irradians effects of age and al lozyme heterozygosity on reproductive out-put. Mar. Biol. 113:253-261. Bricelj, V. M. and R. E. Malouf. 1980. Aspects of reproduction of hard clams (Mercenaria mercenaria) in Great South Bay, New York. Proc. Natl. ShellC. Assoc. 70:216-229. Bricelj, V. M., J. Epp and R. E. Malouf 1987. Comparative physiolo-gy of young and old cohorts of bay scallop Argopecten irradians (Lamarck): mortality, growth and oxygen consumption. J. Exp Mar. Biol. Ecol. 112:73-91. Brousseau, D. J. 1978. Spawning cycle, fecundity and recruitment in a population of soft-shell clam, Miya arenaria from Cape Ann, Massachusetts. Fish. Bull. U. S. 76:155-166. Brousseau, D. J. 1979. Analysis of growth rate in Mya arenaria using the vonBertalanffy equation. Mar. Biol. 51:221-227. Brousseau,'D. J. 1987. A comparative study of the reproductive cycle of the soft-shell clam, Mya arenaria in Long Island Sound..L Shellf Res 6:7-15. Brousseau, D. J. and J. A. Baglivo. 1984. Sensitivity of the population growth rate to changes in single life history parameters: its appli-cation to Mya arenaria (Mollusca:Pelecypoda). Fish. Bull. U. S. 82:537-541. Brousseau, D. J. and.. A. Baglivo. 1987. A comparative study of age and growili in V/,a atonaria (soft-shell clam) 1rotm three popula-tions in Lon, Island Sound. J Shellf. Res. 6:17-24. Broursseau, D. J. and.1. A. Baglivo. 1988. Life tables for two field populations of soft-shell clam, 1tva arenaria (MolIusca:Pclecypoda) front Long Island Sound. Fish. Bull. U. S. 86:567-579. Broutsseau. D. J. and.1. A. Baglivo. 1991. Disease progression and mortal ity in neoplastic V/ya aienatrriea in the field. Mar. Biol. 110:249-252. Brousseaur. D. J.. J. A. Baglivo and G E. Lang. 1982. Estimation of equilibriutm settlement rates for benthic marine invertebrates: its application to Mva aoenareia (Mollusca:Pelecypoda). Fish. Bull. 80:642-644. Buchsbaum, R. (ed.). 1992. Turnrio the tide: Toward a livable coast in Massachusetts. Mass. Audubon Society, Lincoln, MA. 121p. Bumpus, H. C. 1898. The breeding of animals at Woods Hole during months ofJtrie, July and August Science, New Ser. 8:850-858. ,Caddy, J. F. 1980. Recent developments in research and management for wild stocks of bivalves and gastropods, p. 665-701, In: Marine Invertebrate Fisheries: Their Assessment and Management (J. F. Caddy, ed.), John Wiley and Sons, New York. Caporale. D. A, 13. F. Beal, R. Roxby and R. J. Van Beneden. 1997. Population structure of V/ya a-enatio along the New England coastline. Mol. Mar. Biol. Bioteclinol. 6:33-39. Castagna, M. and 1. Chanley. 1973. Salinity tolerance of some marine bivalves from estuarine environments in Virginia waters on the western mid-Atlantic coast. Malacologia 12:47-96. Castagna, M. and J. N. Kraeuter. 1981. Manual for growing the hard clam MeV/cenaria mrewena1aia. Va. Instit. Mar. Sci. Spec. Rept. No. 249, 110 pp. Caswell, H. and P. Werner. 1978 Transient behavior and life history analysis of teasel, Dipsac its.syhrestis. Fcology 59:53-66. Chanley,P. E. 1957. Survival of some bivalves ii waters of low salin-ity. Proc. Natl. ShellEl Assoc. 48:52-65. Chesmore, A. P., S. A. Testaverde and F. P. Richards. 1971. A study o the marine resources of Dorchester Bay. Mono. Ser. 10, Mass. Div. Mar. Fisheries, 44pp. Chesmore, A. P., D. J. Brown, R. D. Anderson. 1972. A study of the marine resources of Lynn-SmiuEus I larbor. Mono. Ser. I1, Mass. Div. Mar Fisheries, 40pp. Chesraore, A. P., D. J. Brown and R. D. Anderson. 1973. A study of the marine resources of Essex Bay. Mono. Ser. 13. Mass. Div. Mar. Fisheries, 38pp. Coe, W. R. and H. J. Turner, Jr. 1938. Development of the gonads and gametes in the soft-shell clam (Mya arenaria)... Morohol. 62:9 I-III. Commito, J. A. 1983. Naticid snail predation in New England: The eftects of Lunatia hJeros on the population dynamics of Mya are-naria and Macoina bal/hica. J. Shellf. Res. 3:87. Connel, R., R. E. Loveland and W. Cokeley. 1981. Factors of mortality and growth in an intertidal population of juveniles of Mercenaria anercenaria from Shark River, New Jersey over a two-year period. J. Shellf. Res. 2:92. Cosper, E. M., W. C. Dennison, E. J. Carpenter, V. M. Bricelj, J. G Mitchell, S. 1-. Kuenstner, D. Colflesh and M. Dewey. 1987. Recruitment and persistent brown tide blooms perturb coastal marine ecosystem. Estuaries 10:284-290. Creaser, E. P. and D. E. Packard. 1993. Commercial length, catch/effort and landings of soft-shell clams (Mya arenaria) from an undug intertidal population at Machiasport, Maine. J. Shellf Res. 12:311-319. Curley, J. R., R. P. Lawton, D. L. Chadwick and K. Reback. 1974. A study of the marine resources of Taunton River-Mount Hone Bay. Mono. Set. No. 15, Mass. Div. Mar. Fisheries, 37pp. Curley, J. R., R. P. Lawton, J. M. Hickey and J. D. Fiske. 1970. A study of the marine resources of the Waquoit Bay-Eel Pond
Estuars. Mono. Ser. 9. Mass. Div. Mar. Fisheries, 4)pp. Curley,.1. R., R. P. Lawton, D, K. Whittaker and J. M. Hickey 1972 A study of the marine resources of Wellfleet Harbor. Mono. Ser. No. 12, Mass. Div. Mar. Fisheries, 37pp. Curley, J. R., K. E. Reback, D. L. Chadwick and R. P. Lawton. 1975. A study of the marine resources of the Bass River. Mono. Ser. No. 16, Mass. Div. Mar. Fisheries, 33pp. Dalton, R. and*W. Menzel. 1983. Seasonal gonadal development of young laboratory-spawned southern (Mercenaria campechiensis) and northern (Mercenaria inercenaria) quahogs and their recipro-cal hybrids ii northern Florida. J. Shell[' Res. 2:11-17. Deegan, L.. and R. B3uchsbaum. Chapter 5. this volume. Deevey, F. S. 1947. lili tables for natural populations of animals. 2 Rev. Biol. 22:283-3 14. Deevey, G. 13. 1948. The zooplankton ol'Tisbury Great Pond. Bull. Binaham Oceanoor. Coil. 12:1-44. DIlon, R. T. Jr. and J. J. Manzi. 1992. Population genetics of the hard clam. Mercenaria mercenaria at the northern limit of its range. Can. J. Fish. Aquat. Sci. 49:2574-2578. Dunn, R., L. S. Mullineaux and S. W. Mills. 1999. Resuspension of' postlarval soft-shell clams hMjra arenaria through disturbance by the mud snail llyanassa obsoleta. Mar, Ecol. Propr. Ser. 180:223-232. Edwards, 1). C. and J. 1). l Icubner. 1977. Feeding and growth rates of Polinices duplicaus preying on AIya arenoria at Barastable Harbor. Massachusetts. Ecologv 58:1218-1236. Emerson, C. W. and J. Grant. 1991. The control of the soft-shell clam (A'ya arenaria) recruitment on intertidal sandtlats by bedload sediment transport. Limnol and Oceanoar. 36:1288-1300. Enright, N and.1. Ogden. 1979. Application of transition matrix model in forest dynamics, Araucaria in Papua New Guinea and Notholaus in New Zealand. Austr.J. Ecol. 4:3-23. Estrella, B.T. and S.X Cadrin. 1992. Massachusetts coastal commercial lobster trap sampling program May-November, 1991. Coinmonw. Mass. Div. Mar. Fish. Pubi. # 17180 150-8/92, 23 p. Eversole, A. G. 1989. Chapt. 3: Gametogenesis and spawning in North American clam populations: implications for culture. In: Developments in AquacUlture and Fisheries Science, 19, Clam Mariculture in North America. (Manzi, J. and M. Castagna, eds.). Elsevier, New York. Eversole-A. G.. W. K.Michcner and P. J. Eldridge. 1980. Reproductive cycle of Alerceocaria mnercenaria in a South Carolina estuary. Proc. Natl. Shellf. Assoc. 70:20-30. Farley, C. A. 1969. Sarcomnatoid proliferative disease in a wild popu-lation of blue mussel (Mytilus edilis). J. Natl. Cancer Inst. 43:509-516. Feder, H. M. and A. J. Paul. 1974. Age, growth, and size-weight rela-tionships of the soft-shelled clam Mya arenaria in Prince William Sound, Alaska. Proc. Nat]. Shelltf Assoc. 64:45-52. Fiske, J. D., J. R. Curley and R. P. Lawton. 1968. A study of the marine resources of the Westport River. Mono. Ser. 7, Mass. Div. Mar. Fisheries, 52pp. Fiske, J. D., C. E. Watson and P. G. Coates. 1966. A study of the marine resources ofthe North River. Mono-Ser. 3, Mass. Div. Mar. Fisheries, 53pp. Fiske, ). D., C. E. Watson and P. G. Coates. 1967. A study of the marine resources of Pleasant Bay. Mono. Ser. 5, Mass. Div. Mar. Fisheries, 56pp. Gallagher, S. M., D. K. Stoecker and V. M. Bricelj. 1989. Effects of the brown tide alga on growth, feeding physiology and locomoto-ry behavior of scallop larvae(Argopecten irradians). p. 511-541 In: Cosper, E. M., V. M. Bricelj and E. J. Carpenter, eds. Novel Phytoplankton Blooms: Causes and Impacts of Recurrent Brown Tides and Other Unusual Blooms. Coastal and Estuarine Studies
- 35. Springer-Verlag, Berlin.
Gledhill, C. 1980. The influence of established infauna on recruitment of the soft-shell clam, Mya arenaria L. M. S. Thesis, Univ. INSiiORE BIVALVE MORTALITY AND 1iARVESTING 11 5 Massachusetts. Amherst, 40 p. Glide. J. B. 1954. The effects of temnperature and predators on the abundance of the soft-shell clam, A.Iya arenarta, in New England. Trans. Airer. Fish. Soc. 84:13-26. Grewe, P. M, N. G. Elliott, B. H. Innes and R. D. Ward. 1997. Genetic population structure of southern bluefin tuna (Thunniis macco'i). Mar. Biol. 127:555-561. Guenther. C. IR 1992. Settlement and recruitment of Mya arenaria L. in the Wadden Sea. J. Exol Mar. Biol. Ecol. 159:203-215. Gulland, 1. A. 1974 The Managenient of Marine Fisheries. John Wright and Sons. Dorchester, England, 198 p. GutselI, J. S. 1930. Natural history of the bay scallop. Bull. U. S Bur. Fish. 46:569-632 Hancock, D. A. 1973. The relationship between stock and recruitment ir exploited invertebrates. Rapp. P.-V. Reun., Cons. Perm. int. Explor, Mer. 164:113-131. Hanski, I. and M. Gilpin. 199 1. Metapopulation dynamics: brief histo-ry and conceptual domain. Biol, J. Linnean Soc, 42:3-16. Hartshorn, G. 1975. A matrix model for tree population dynamics. In: Tropical Ecology Systems (F. G. Golley and F. Medina, eds. ), p. 45-5 i, Springer-Verlag, New York. Haven, D. S., W. J. Hargis, J. G. Loesch and J. P. Whitcomb. 1975. The effect of tropical storm Agnes on oysters, hard clams, soft clams and oyster drills. Chesapeake Research Consortium PubI ication No. 34: D 170-1D208. Solomrons, MD. Ilesselmanr D. M, B. J. Barber and N..1. Blake. 1989. The reproduc-tive cycle of hard clams, Mercenaria spp. in the Indian River Lagoon, Florida. J. Shellt' Res. 8:43-49. 1-libbern, C. J. 1977. Growth and survivorship in a tidalflat population of the bivalve A.ercenaria mnercenaria from Southampton water. Mar. Biol. 44:71-76. Hunt, [.E. and R.E. Scheibling. 1997. Role ofearly post-settlement mortality ii recruitment of benthic marine invertebrates. Mar. Ecol. Prog4 Ser. 155:269-301. lwanowicz, H. R., R. D. Anderson and 13. A. Ketschke. 1973. A study of the marine resources of Hingliam Bay. Mono. Ser. No. 14, Mass. Div. Mar. Fisheries, 40pp. hvanowicz, H. R.7 R D. Anderson and B. A. Ketschke. 1974. A study of the marine resources of Plymouth-Kingston-Duxbury Bays. Mono. Ser. No. 17, Mass. Div. Mar. Fisheries, 37pp. Jerome, W. C., Jr., A. P Chesinore, C. 0. Anderson, Jr. and F. Grice. 1965. A study of the marine resources of the Merrimack River Estuary. Mono. Ser. No. I, Mass. Div. Mar. Fisheries, 90pp. Jerome, W. C., Jr., A. P. Chesinore and C. 0. Anderson Jr. 1966. A study of the marine resources of Quincy Bay. Mono. Ser. No. 2, Mass. Div. Mar. Fisheries, 61pp. Jerome, W. C., Jr., A. P. Chesmore and C. 0. Anderson, Jr. 1967. A study of the marine resources of Beverly-Salem Harbor. Mono. Ser. No. 4, Mass. Div. Mar. Fisheries, 74 pp. Jerome, W. C. Jr., A. P. Chesmore and C. 0. Anderson, Jr. 1968. A study of the marine resources of the Parker River-Plum Island Sound Estuary. Mono. Ser. 6, Mass. Div. Mar. Fisheries, 81 pp. Jerome, W. C. Jr., A. P. Chesmore and C. 0. Anderson, Jr. 1969. A study of the Annisquarm River-Gloucester Harbor Coastal System. Mono. Ser. 8, Mass. Div. Mar. Fisheries, 62pp. Johnson, R. G: 1965. Temperature variation in the infaunal organisms ofa sandflat. Limnol: Oceanogr. 10:114-120. Johnson, R. G. 1967. Salinity of intertidal water in a sandy beach. Limnol. Oceanopr. 12:1-7. Jones, D.S., M. A. Arthur and D. J. Allard. 1989. Sclerochronological records of temperature and growth from shells of Mercenaria mercenaria, Narragansett Bay, Rhode Island. Mar. Biol. 102:225-234. Juste, V. 1992. Heterozygote deficency in seven populations of the hard clam Mercenaria mercenaria (Linn.). J. Shellf. Res. 11:197-198. Kassner, J. and R. E. Malouf. 1982. An evaluation of "spawners trans-
1 16 B RO I iSiE-AtJ plants" as a managemenit tool in Long Island's haid clam fishery. J. Shellff Res. 2: 165-172. Keck, R. T1., D. Maurer and H. Lind. 1975. A comparative study ol' the hard clam gonad developmental cycle. Biol. Bull. 148:243-258. Kellog, J. L. 1905. Report of the special commission 'or the investi-gation of the lobster and the soft-shell clam IV. Conditions gov-erningcexistence and growth of the solt clam (Ai)'a areiiria). Rep. U. S. Comm. Fish Comm. 29:195-224. Kelso, W. E. 1979. Predation on soft-shell clams, AIyoa arenaria, by common muiamichog, Fundulus heteroclitus. Estuaries-2:49-254. Kraeuter, J. N. and M. Castagna. 1985. Effects of large predators on the field culture of the hard clam, Alercenaria 'nercenaria. Fish. Bull. 78:538-541. Kracuter, J. N. and M. Castagna. 1989. Chapter 6: Factors aliecting the growth and survival of clam seed planted in the natural envi- .ronment. In: Developments in Aquaculture arid Fisheries Science, 19, Clam Mariculture in North America (Manzi, J. J. and M. Castagna, eds.). Elsevier Press, New York. Landers, W. S. 1954. Seasonal abundance of clam larvae in Rhode Island wraters, 1950-1952. U. S. Fish. Wildl. Serv. Spec. Sci. Rep. Fish. 117, 29pp. Larkin, P. A. 1972. The stock concept and management of P'acific salhon. 11. R. MacMillan Lectures in Fisheries, University of British Columbia, Vancouver, 231 pp. Leslie, P. 1-. 1945. Oin the use of matrices in certain population math-ematics. Biomnetrika 35:183-212. Leslie, P. H. 1948. Some further notes on the use of matrices in popu-lation mathematics. Biometrika 38:213-245. Levin, L. A., H-1. Caswell, D. DePatra and E. L. Crego. 1987. Demographic consequences of larval development mode: plank-totrophy vs. lecithotrophy in Streblospio benedicti. Ecolo~gy 68:1877-1886. Loosanoll, V. L. 1937a. [)cvclopmcnt of the primary gonad and sexu-al phases in ('enus mercenaria Linnaeus. Biol. Bull. 72:389-405. Loosanol, V. L. 1937b. Seasonal gonadal changes of adult clams, Venus mercenaria (L.). Biol. Bull. 72:406-4 16. Loosanofl V. L. and 1. C. Davis. 1950. Conditioning F, mercenaria for spawning in winter and breeding its larvae in the laboratory. Biol. Bull 98:60-65. Loosanofl, V. L. and 11 C Davis. 1963. Rearing of bivalve molluscs. Adv. Mar. Biol. 1:1-136. Longstaft, B. C. 1977. The dynamics ofcollembolan populations: a matrix model of single species population growth. Can. J. Zool. 55:314-324. Luckenbach, M. W. 1984. Settlement and early post-settlement sur-vival in the recruitment of Mulinia lateralis (Bivalvia). Mar. Biol. Pia. Ser 17:245-250. MacKenzie, C. L. 1977. Predation on hard clam Mercenaria merce-naria populations. Trans. Amer. Fish. Soc. 106:530-536. MacKenzie, C. L. 1994. Description of an unusually heavy set of soft-shells (Mya arenaria) and other bivalves in northern New Jersey, Long Island Sound and southern New England in 1993. J. Shellf. Res. 13:317. Malinowski, S. A. and R. B. Whitlatch. 1988. A theoretical evaluation of shellfish resource management. J. Shellf Res. 7:95-100. Mamturis, Z., A. P. Apostolidis, A. J. Theodorou and C. Triantaphyllidis. 1998. Application of random amplified polymor-phic DNA (RAPD) markers to evaluate intraspecific genetic vari-ation in red mullet. Mar Biol 132:171-178. Manzi, J. J., M. Y. Bobo and V. G. Burrell, Jr. 1985. Gametogensis in a hard clam, Mercenaria mrercenaria, population in North Santee Bay, South Carolina. Veliger 28:186-194. Matthiessen, G. C. (ed.). 1992. Perspective on Shellfisheries in Southern New England. The Sounds Conservancy, Inc. Pub[. #4, Essex, CT. 60p. MBP (Massachusetts Bays Program). 1996. Massachusetts Bays Programn Comprehensive Conservation and Manaogement Plan: An Evolving Plan for Action. Massachusetts Bays Program, Boston, MA. McDowell, J. Chapter 7, this volume McLaughlin, S. M. & M. Faisal. 1997. Isolation of Perkinsus sp. from the so't shell clam (Mya arenaria). J. Shellf Res. 16:335 Mead, A. D. and E. W. Barnes. 1903. Observations on the soft-shell clam, M1ya arenaria. Rep. Rhode Island Comm. Inland Fish. 22:29-46. Mead, A D and E. W. Barnes 1904. Observations on the so't-shell clarn. R. I. Comm. Inland Fisheries, 34th Ann. Rept. 29-68. Menzie-Cura Associates, lic. 1996. Identification of Massachusetts Bays Embaymnents at Risk of Eutrophication. Technical Report No. MBP 96-02. Massachusetts Bays Program, Boston MA. Micheli, F. 1997. Effects of predator foraging behavior ott patterns or prey mortality in marine soil bottoms. Ecol. Monogr. 67:203-204. Moller, P. and R. Rosenberg. 1983. Recruitment, abundance and pro-duction of Mya arenaria and Cardium edule in marine shallow waters, Western Sweden. Ophel ia 22:33-55. Morgan, R. P., S. B. Block, N. I. Ulanowicz and C. Buys. 1078. Genetic variation in the soft-shell clam, Mya arenaria. Estuaries 4: 255-258. Munch-Petersen, S. 1973. An investigation of a population of the soft clam (A/ia areinaria L.) it a Danish estuary. Meddr. Kommni. Dant. Fisk.-o-I Hawtinders. (Ser. 3) 7:47-73. Murawski, S. A. and 1. S. Idoine. 1989. Yield sustainability under constant-catch policy and stochastic recruitment. Trans. Amer. F 118:349-367. Muus, K.1973. Settling, growth and mortality of young bivalves in the Oresund. Opphelia 12:79-116. Nelson, T. C. and E. B. Perkins. 193 1. Annual Report of the Dept. of Biology, July I, 1929-June 30, 1930. N. J. Agric. Expt. Star. Bull. No. 522:1-47. Ncwcontbc, C.L. 1935. Growth of Alya arenaria in the Bay of Fundy region. Can. J. Res. 13:97-137. Newell, C. 1982. 'Flse effects of sediment type on growth rate and shell allometry in the soft-shelled clam Mya arenaria. J. Exp. Mar, Biol. Ecol. 65:285-295. Newell, C. and I-I. Hidu. 1986. Species Profiles: Life Histories and E*nvironinental Requirements of Coastal Fishes and Invertebrates (North America) - Softshell Clam. U.S. Fish and Wildlife Service Biological Report 82(11.53) and U.S. Army Corps of Engincers TR EL-82-4. 17 pp. NOAA (National Oceanic and Atmospheric Administration). 1999. Current Fishery Statistics of the United States, 1983 - 1999. Washington, D. C. Parker, M. R., B. E. Beal, W. R. Congleton Jr., B. R. Pearce and L. Morin. 1998. Utilization of GIS and GPS for shellfish growout site selection. J. Shellf. Res. 17:1491-1495. Peterson, C. H. and H. C. Summerson. 1992. Basin-scale coherence of population dynamics of an exploited marine invertebrate, the bay scallop: implications off recruitment limitation. Mar. Ecol. Proo. Ser. 90:257-272. Peterson, C. H., H. C. Summerson, S. R. Fegley, and R. C. Prescott. 1989. Timing, intensity and sources of autumn mortality of adult bay scallops Argopecten irradians concentricus Say. J. Exo. Mar, Biol. Ecol. 127:121-140. Pfitzenmeyer, H. T. 1962. Periods of spawning and setting of the soft-shelled clam, Mya arenaria at Solomons, Maryland. Ches. Sci. 3:114-120. Pfitzenmeyer, H. T. and K. G. Drobeck. 1963. Benthic survey for pop-ulations of soft-shelled clams, Mya arenaria in the lower Potomac River, Maryland. Ches Sci 8:193-199. Pinero, D., M. Martinez-Ramos and J. Sarukhan. 1984. A population model for Astrocaryum mexicanumn and a sensitivity analysis of its finite rate of increase. J. Ecol. 72:977-991. Pline, M. J. 1984. Reproductive cycle and low salinity stress in adult
Mecenaria inerceuaria L. of Wassaw Sound, Georgia. M. Sc. Thesis. Georgia Institute of"Technology, Atlanta, 74 pp. Pogson, G. H., K. A. Mesa, and R. G. Boutilier. 1995. Genetic popula-tion structure and gene Ilow in the Atlantic Cod, Godas norhluta: a comparison of allozyme and nuclear RFLP loci. Genetics 139:375-385. Pohle, D. G, V. M. Bricelj and Z. Garcia-Esquivel. 1991. The ceigrass canopy: in above-bottom refuge from benthic predators fur juve-nile bay scallops. irgopecten irradians. Mar. Ecol. Proo. Ser. 74: 47-59. Porter, H. 1964. Seasonal gonadal changes of adult clams, Mkermenaria mercenoaria (L.) in North Carolina. Proc. Natl Shellf Assoc. 55 35-52. Porter. R. G. 1974. Reproductive cycle of the soft-shell clam. Mvya arenaria at Skagit Bay, Washington. Fish. Bull. U. S. 72:648-656. Rice, M. A: 1996. The 1995 status of the shellfisheries for the north-ern quahog, Mercenaria mercenaria (L.) in New England. J. Sheltf Res. 15:481. Rice, M. A., C. Hickox and 1. Zehra. 1989. Effects of intensive fish-in, effort on the population structure of quahogs. Mercenaria mercenaria (Linnaeus 1758), in Narragansett Bay. J. Shell f Res. 8:345-354. Ricker, W. E. 1975. Computation and interpretation of biological statistics of fish populations. Bull. Fish Res. Bd. Can. 191:1-382. Ripley, B..I. and H. Caswell. 1996. A theoretical analysis of the role of recruitment variability in structuring populations of the steamer clam, Mya arenaria. In: Woodin, S.A., D.M. Allen, S. E. Stanyck, J. Williams-Hlowze, R. J. Feller, D. S. Wethey, N. D. Pentchelt, G. T. Chandler, A. W. Dechol and B. C. Coull (eds.), 24th Ann. Benthic Ecology Meeting, Columbia. SC, Mar. 7-10, 1996, p. 7 1. Rogers, W. E. 1959. Gonad development and spawning of the soft clam. Maryland Tidewater News 15:9-10. Ropes, J. W. and A. P. Stickney. 1965. Reproductive cycle of yI/a arenaria in New England. 13iol. Bull. (Woods Hole) 128:315-327. Rorres, C. & W. Fair. 1975. Optimal harvesting for an age specilic population. Math. Biosci. 24:3 47. Rowell, T. W. and P Woo. 1990. Predation by the nemertean worm, Cerebratulus lacteus Verrill. on the soft-shell clam, ilMya arenaria Linnaeus, 1758, and its apparent role in the destruction of a clam fiat. J ShelIIf Res. 9:291-297. Sanders, H.L. PV C. Mangelsdorl'. Jr. and G. R. Hampson. 1965. Salinity and faunal distribution in the Pocasset River. Massachusetts. Limnol. Oceanor. 10 (Suppl.), p. R216-R229. Sanders, H. L., E. M. Gouldsmit, E. L. Mills and G. E. Hanipson. 1962. A study of the intertidal fauna of Barnstable Harbor, Massachusetts. Limnol. Oceanoer 7:63-79. Sastry, A. N. 1963. Reproduction of the bay scallop, Aequipecten irradians Lamarck, influence of temperature on maturation and spawning. Biol. Bull. 125:146-153. Sastry, A. N. 1966. Temperature effects in reproduction of the bay scallop, Argopecten irradians Lamarck. Biol Bull. 130:118-134. Sastry, A. N. 1968. The relationships among food, temperature and gonad development of the bay scallop, Aequipecten irradians Lamarck. Physiol. Zool. 41:44-53. Schmeer, M. R. 1964. Growth-inhibiting agents from !tercenaria extracts: chemical and biological properties. Science 144:413-414. Scribner, K. T., P. A. Crane, W. J. Spearman & L. W. Seeb. 1998. DNA and allozyme markers provide concordant estimates of pop-ulation differentiation: analyses of U. S. and Canadian popula-tions of Yukon Rver fall run chum salmon (Oncorhynchus keta). J. Can. Fish. Aquat. Sci.55:1748 1758. Shaw, W. N. and F. Hamons. 1974. The present status of the soft-shell clam in Maryland. Proc. Natl. Shellf. Assoc. 64:38-44. Shepherd, S. A. and L. D. Brown. 1993. What is an abalone stock: implications for the role of refugia in conservation. Can. J. Fish. Aguat. Sci. 50:2001-2009. INSHORE BIVAIVt NIORTALITV ANt) I.ARVESTIN(; I 7 Siddall, S. E. and C. I... Nelson. 1986. Failure of bay scallop larval recruitment during Long Island's "brown tide" of 1985. Paper presented at the 6th Annual Shellfish Biology Seminar, 4 March, 1986, Milford, CT Smith, 0. R. 1952. Results o'experimental soft clam farming in Plum Island Sound. Mass. Third Annual Conf. on Clam Research. U. S. Fish and Wildl. Scrv., Boothbay Hlbr., Me. pp. 39-41. Smith, 0. R, J, P. Baptist and E. Chin. 1955. Experimental farming of the soft-shell clam, Mj'a arenaria in Massachusetts. 1949-1953. Commer. Fish. Rev. 17:5-16. Smith, T. E., R. C. Ydenberg and R. W. I"Iner. 1999. Foraging behav-ior oran excavating predator, the red rock crab (Cancer productus Randall) on soil-shell clam (Alyoa arenaria I..). J. Fxn. Mar. Biol. Ecol. 238:185-197. Smolowitz, R., D. Leavitt and aF. Perkins. 1998. Observations of a Protistan disease similar to QPX in Alercenaria mnercenaria (hard clams) from the coast of Massachusetts. J. Invert. Pathol. 71:9-25. Snelgrove, P. V. R., J. Grant and C. A. Pilditch. 1999. Habitat selec-tion and adult-larval interactions in settling larvae of soft-shell clam Alta arenaiao. Mar. Ecol. ProorSer. 182:149-159. Spear, H. S. and J. B. Glude. 1957. Effects of environment and hered-ity on growth of the soft clam (Mya arenaria). Fish. Bull. 57:279-292. Stafford, J. 1912. On the recognition of bivalve larvae in plankton collections. Contrib. Can. Biol. Fish. 1906-1910 22 1-242 Stevenson, J. R. 1907. Report of J. R. Stevenson upon observations and experiments on mollusks in Essex County during 1906. In: Rept. Comm. Fish and Game 1906, Commonwealth of Massachusetts, Public Doc. 25:68-96. Sullivan. C. M. 1948. Bivalve larvae of Malpeqcue Bay, P.E.I. Fish. Res. Bd. Can. tull. 77, 36pp. Summerson, H. C. and C. 11. Peterson. 1990. Recruitment failure of the bay scallop, A-rgopctlemm irrOdiamis concentricus during the first red tide, Piychlodiscus brevis, outbreak recorded in North Carolina. Estuaries 13:322-331. Swan, E. F. 1952. Growth of the clam Alya aretnaria as affected by the substratum. Ecology 33:530-534. Tammi, K. A, W. H. Turner and M. A. Rice. 1997. The influence of temperature on spawning and spat collection of the bay scallop. .4rgopecten irra/ians in southeastern Massachusetts waters. USA. .1 ShelIf Res. 16:349. Tettelbach, S. T. and E. W. Rhodes. 198 1. Combined effects of tem-perature and salinity on embryos and larvae of the northern bay scallop, Argopecten irradians. Mar. Biol. 63:249-256. Tettelbach, S. T. and P Wenczel. 1993. Reseeding efforts and the sta-tus of bay scallop Argopecten irradians (Lamarck, 1819) popula-tions in New York following the occurrence of "brown tide" algal blooms. J. Shellf Res. 12:423-431. Tettelbach, S. T., C. F. Smith, R. Smolowitz, K. Tetrault and S. Dumais. 1999. Evidence for fall spawning of northern bay scal-lops Argopecten irradians (Lamarck 1819) in New York. J. Shellf Res. 18:47-58. Thayer, G. W., W. J. Kenworthy and M. S. Fonesca. 1984. The ecology ofeelgrass meadows of the Atlantic coast: A community profile. USFWS, FWS/OBS-84/02, 147 pp. Turner, H. J. Jr. 1949. The soft-shell clam industry of the east coast of the United States. Appendix 1. Report on the investigations of the propagation of the soft-shell clam, Aya arenaria. Woods Hole Oceanogr. Inst., Coll. Reprints, 1948, Contrib. 462, p. 11-42. Uzmann, J. R. 1952. Cercaria nyoae sp. nor., a fork-tailed larva from the marine bivalve, Mya arenaria. J. Parasitol. 38:161-164. Vassiliev, T., W. Congleton, B. Beal and S. Fegley. 1999. An investi-gation of Mya arenaria (soft-shell clam) recruitment in Maine. J. Shellf Res. 18:311-312. Virnstein, R. W. 1977. The importance of predation by crabs and fishes on benthic infauna in Chesapeake Bay. Ecology 58:1199-1216.
I 18 BRouSSFA.I Warwick, R. M. and R. Price. 1975. Macroftuna production in an estuarine mnudflat..1. Mar. Biol. Assoc. U. K. 55:1-18. Weber, L. I., 1. P. Thorpe, R. S. Santos and S. J. Hawkins. 1998. Identification ot stocks of the exploited limpets Patella aspera and P. candei at Madeira archipelago by allozme electrophoresis. J Shell', Res 17:945-953. Weinberg, J. R., D. F. Leavitt, 1B. A. Lancaster and J. M. Capuzzo. 1997. Experimental field studies with Mya/ arenaria (Bivalvia) on the induction and elflct of hematopoietic neoplasia. J. Invert. Pathol. 69:183-194. Welch, W. R. 195-3. Seasonal abundance of bivalve larvae in Robinhood Cove. Maine. Fourth Ann. Conf. on Clam Res., U. S. Fish and Wildl. Serv.. Clam Investigations, Boothbay Harbor, Maine. Whyte, S. K., R. J. Cawthorn and S. El. McGladdery. 1994. QPX (Quahaug Parasite X), a pathogen of northern quahaug Mercenaria mercenaria from the Gulf of St. Lawrence, Canada. Dis. Aquat. Org. 19:129-136. Wilbur, A. E., W. S. Arnold and T. M. Bert. 1999. Evaluating bay scallop stock enhancement efforts with molecular genetic markers. .1. Shellf Res. 18:315-316. Wilding, C. S., J. W. Latchford and A. R. Beaumont. 1998. An inves-tigation of possible stock structure in Pecien maximus (L.) using multivariate inorphontetrics, allozyine electrophoresis and mito-chondrial DNA polymerase chain reaction-restriction fragment length polymorphism.1. Shelll Res. 17:131 - 139. Williams, J. G. 1980. The influence of adults on the settlement of spat of the clam, Tapesjaponica. J. Mar. Res. 38:729-74 1. Wiltse, W. I. 1980. Predation by juvenile Polinices duplicatus (Say) on Getmma gemina ('Ibtten). I Fxp. Mar, Biol, Ecol, 42:187-199. Witn, R. N. and 1). M. Knott. 1992. An evaluation of the survival of experimental populations exposed to hypoxia in the Savannah River estuary. Mar. Ecol. Proi. Ser. 88:161-179.34:25-41. Zobrist, E. C. and 13. C. Coull. 1994. MeioftLunal effects on growth and survivorship of the polychaete Streblospio benedicti (Webster) and the bivalve M'ercenaria inercenaria (L.)... Exp. Mar. Biol. Ecol. 175:167-179.
(ONTO I;N AlION IFIF(I5.C AND MIONITOR IN(;1 NIF \\lRIN E S1111II.Ilfn I 19 Chapter VU Biological Effects of Contaminants on Marine Shellfish and Implications for Monitoring Population Impacts JUDITH E. McDOWELL l4'bods Hole Oceanographic Institution Department of Biology l'Toods Hole. A44A 02543 USA INTRODUCTION The integrity of the worl's coastal waters is jeopardized by the deliberate and inadvertent entries of societ,'s dis-cards. Mla[any substances itilroduced by, ,nankind are toxic to marine organisms, thus impinging upon the health of ocean communities or restricting the human cons umption offish and shellfish. -Edward D. Goldhera 1980 The use of a sentinel species as an indicator of chemical contamination has been widely used in monitoring programs in the marine environment (Bayne et al., 1988; Jones et al., 1995). This approach has led to greater insights on the spatial and temporal distribution of contaminants and associated effects on sentinel species (Butler, 1973; NRC, 1980; Farrington et al., 1983; Bayne et al., 1988). Bivalve molluscs, including several species of mussels, oysters and clams, have been the most commonly used sentinel species in Mussel Watch monitoring programs. Although our knowledge of the distribution of specific compounds and groups of compounds continues to increase, our understanding of cause and effect relationships between classes of contam-inants and specific biological effects in bivalve molluscs is still lacking. Natural biogeochemical processes that ultimately control contaminant bioavailability and uptake by bivalve molluscs must also be examined when evaluating the poten-tial of bivalve molluscs as indicators of chemical contamination. These biogeochemical processes influence contaminant persistence and bioavailabil-ity, ultimately controlling the fate and effects of these contaminants in coastal marine environments. The purpose of this chapter is to evaluate the effects of contaminants on molluscan shellfish from the New England area, and to place these effects in context against the impacts caused by habitat degradation and overfishing. Much of the bivalve monitoring data that has been collected in the region can be used to augment findings from labora-tory and field studies, and help us to assess the impacts of contaminants on populations and individuals. CONIAMINANT DISTRIBUTIONS IN SEDIMENTS AND SIELFISII Regional studies in the Gulf of Maine have documented the spatial distribution of several classes of contaminants including trace metals, chlorinated pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAlIs) in sediments and biota (Larsen, 1992; Kennicutt et al., 1994). These studies have been reviewed in detail elsewhere (McDowell, 1995, .1997). The relationship between contaminant
I 20} X:OW I inputs and the distribution of contaminants in sedi-ments and biota largely reflect a gradient, with nearshore areas, especially urban and industrialized areas, having the highest levels of contamination., and offshore areas having significantly lower con-centrations. The first U.S. Mussel Watch program (1976-1978) provided a regional assessment of contaminant distribution in bivalve samples from New England waters (Farrincton et al., 1983-Goldberg et al.. 1983). Data collected in this program documented the strong urban influence on contaminant distribu-tion in mussel samples for both trace metal and organic contaminants. A recent review of a decade of data collected in the Mussel Watch component of National Oceanic and Atmospheric Administration's (NOAA) National Status and Trends Prograin (in id-1980s to mid-1990s) con-cludes that the concentrations of contaminants in bivalve samples are declining for many classes of contaminants (O'Connor, 1998). Exceptions to this general conclusion are reflected in the data for organic contaminants and lead, particularly at sta-tions in urban areas such as Boston Harbor. To a large extent contaminant distribution in sediments and biota reflect not only contemporary inputs but also a history of industrial activity. For example, chromium contamination in certain loca-tions within the Gulf of Maine ecosystem - Great Bay Estuary (NI-t), Saco River (ME), and Salem Harbor (MA) - reflect a history of inputs from the once thriving tanning industry (Capuzzo and Anderson, 1973; Armstrong et al., 1976; Mayer and Fink, 1980; NOAA, 1991). Concentrations of other trace metals are elevated at other locations - Boothbay Harbor, Boston Harbor and Quincy Bay - and reflect a pattern of wastewater input and other industrial sources of contaminants to shallow water embayments (NOAA, 1989, 1991; Sowles et al., 1992; Jones et al., 1995). Hydrocarbon inputs may also vary spatially and temporally as a result of chronic municipal discharges, agricultural prac-tices, oil spills and other point and non-point sources. In the Gulf of Maine there are numerous locations that have received inputs of petroleum hydrocarbons from both chronic discharges and accidental spills [Boston Harbor (MA), Casco Bay (ME), and Penobscot Bay (ME)] (Johnson et al., 1985; Larsen et al., 1986; MacDonald, 1991; Menzie-Cura & Associates, 1991; NOAA, 1991). The use of chlorinated pesticides in agricultural practices has declined since the early 1970s but traces of pesticide residues have been reported at locations within the Gulf of Maine subjected to inputs from agricultural runoff(Hauge, 1988; Larsen. 1992; Kennicutt et al., 1994). NOAA's National Status and Trends Mussel Watch Program also noted elevated concentrations of aromatic hydrocarbons, chlorinated pesticides and other chlorinated hydrocarbons in bivalve samples, espe-cially in urban harbors and industrialized areas (NOAA, 1989; Jones et al., 1995; O'Connor, 1998). Trophic transfer of contaminants to higher level predators and the human consumer are generally most significant for lipophilic contaminants such as chlorinated hydrocarbons, and other persistent organic pollutants (POPS). Shellfish closures and advisories based on chemical contamination are relatively few but include some examples from the New England coast, notably PCB contamination in New Bedford Harbor and dioxin contamination in Maine (McDowell, 1997). TOxICOI.oIGCAL EFFECTS OF CONTAMINANTS ON SiicA.Tisu The relationship of disease and environ-mental stress is becoming increasingly w,ell established u'ith time. Hunan activi-ties - particularly those that result in chemical additions to the coastal/estuar-ine environmnent - have increased the potential stresses on fish and shellfish inhabiting those areas. Circumstantial evidence for associations of pollutants with certain fish and shellfish diseases and abnormalities is accumulating. -Carl J. Sindermann, 1979 The effects of chemical contaminants on marine bivalve molluscs have been examined extensively during the past two decades. The majority of the studies have been conducted on the blue mussel Mvtilus edulis (e.g., Bayne et al., 1985, 1988) with an effort to integrate responses over several levels of biological hierarchy (Table 7.1) and to examine responses linked to specific classes
ION *['\\,\\I I NA I ION EFFE( I ý;.\\N D MONITOR IN(; OF \\L\\V IN F. ý' I IF LLF I SH 1211 Table 7. I. Response levels of marine organisms to chemical contaminants; adapted from Capuzzo ( 198 1). Level Types of Responses
- Biocheinical-Toxication Cellular i, 'letabolic impairmnent
[Cellular damage Detoxidation Effects at Next Level lIoxic inetabolites Disruption iI energetics and cellular pro-cesses 'Adaptation Or.anismni-Physioloogical changes 'Reduction in 'Behavioral changes population per-Susceptibility to disease formance ReproduCtive effort Regulation and 'Larval viability 1adaptation of Adjustment in rate populations functions 1hnmtine responses Population.ge/'S ize structure lRecruitment !Mortality Biomass Adjustment of repro-ductive output and other demographic characteristics l~ffects on spec.ies! productivity and coexisting species and 1 com in unity Adaptation of population sediment geochem istry research have increased our understanding of processes controlling bioavailabi I-ity and uptake by benthic organisms. The accumu-lation of trace metal and organic contaminants by aquatic organisms is a complicated function of physical, chemical, and biological processes that influence exposure concentrations, bioavailability, and uptake, elimination and storage of contami-nants by an organism (Fisher, 1995). In the benthic environment, nonpolar organic contaminants will partition among all accessible phases according to the capacity of each phase to accumulate the con-taminant. Usually, these partitioning processes are described using equilibrium models. wvhere equilib-rium among all phases is assumed. This forms the basis for Sediment Quality Criteria based on eclui-libriurn partitioning (Shea, 1988; Di Toro et al. 1991 ). Recent studies, however, suggest that bioavai lability of lipophilic contaminants is not based on equilibrium theory alone (McGroddy and Farrington, 1995; McDowell and Shea, 1997). The hydrophobicity of specific contaminants, the source of contaminants, and the sorption of contaminants (especially pyrogenically derived PAH) on organic carbon' particles can greatly influence the rates at which equilibrium may (or may not) be obtained, and hence the availability and uptake of contami-nants by benthic species. Similar concerns exist when considering the bioavailability of trace metals to benthic organisms. Characterizing the bioavailability of trace metals based on the acid volatile sulfide fraction of sediment led to some greater predictability of bioavailability potential (DiToro et al., 1990) but other sediment features and processes (e.g., POC, DOC, metal hydroxides, redox, bioturbation) may also influence bioavailability (Valette-Silver, 1999). Luoma et al. (1997) suggested a combined approach utilizing field observations of sediment concentrations and geochemical properties and laboratory observations of uptake and elimination of specific trace metals from both dissolved and particulate phases (Luoma and Fisher, 1997; Wang et al., 1997). Bioenergetic-based kinetic models are being developed that can better predict the relationship between field and laboratory' observations of uptake and accumulation of metals in benthic organisms (Wang et al., 1996; Wang and Fisher. 1997). Community [Species abund iSpecies distrib Biomass 'Trophic intera 'Ecosystem ada aance Replacement by bution inore adaptive i competitors ctions !Reduced sec-aptition ondary produc-tion No change in community structure and fuinction of contaminants. Recent work has extended this approach to other species of bivalve molluscs and to assessment of population level responses (Widdows et al., 1990; Leavitt et al., 1990; Weinberg et al., 1997; McDowell and Shea, 1997). OUFTAKE AND AccUMULATION Understanding the relationship between sedi-ment contamination and potential for uptake and accumulation of contaminants by benthic organ-isms is a challenging problem. Recent advances in
I22 ? I.:r)OWE f. BIOTRANSFORANIrON ANt) DIsEl"ASL RSI-'ONSES Research on biotransformation mechanisms in marine bivalve molluscs has paralleled efforts oil vertebrate species for over two decades. In compar-ison, bivalve molluscs have been considered to have a relatively low capacitylfor detoxifying organic contaminants through cytochrome P-450 monooxygenase reactions (Anderson. 1978, Livingstone and Farrar, 1984; Stegeman, 1985). The dominant metabolites of benzo(a)pyrene detected in molluscs have been primarily quinone derivatives, rather than the diol derivatives observed in fish (Stegeman. 1985; Stegeman and Lech, 1991), although Anderson (1985) did observe relatively high concentrations of diol derivatives as well. Stegeman (1985) suggested that PAIlI metabolism in bivalve molluscs may proceed through several catalvtic mechanisms including peroxidative mechanisms in addition to cytochrome P-450 monooxygenase. The formation of oxyradi-cals and binding of these reactive compounds to DNA and other macromolecules (Livingstone et al., 1990; Garcia-Martiriez and Livingstone, 1995) pose a link with observations of cell damage noted by other investigators. Metabolism of other com-pounds such as aromatic amines yields metabolites with mutagenic properties (Anderson and Doos, 1983; Kurelec et aL., 1985; Kurelec and Krca, 1987; Knezovich et al., 1988) and DNA adducts (Kurelec et al., 1988). The relationship between biotransfornmation and disease processes in bivalve molluscs has been suggested by several investiga-tors (Moore et al., 1980; Stegeman and Lech, 1991). The reactive compounds formed during biotrans-formation could result in histopathological damage of molluscan tissues. Mix (1986, 1988) reviewed the relationship among contaminant tissue burdens, biotransforma-tion and histopathology/disease in marine bivalve molluscs. Although no conclusions could be made, he suggested that our limited understanding at that time of specific contaminant effects on cellular and physiological processes and mechanisms of bio-transformation hindered our ability to explore the relationship between contaminant exposure and disease progression. Gardner et al. (1991) reported promising evidence on the relationship between contaminant distributions and metabolism and the prevalence of specific tissue neoplasias in the oyster Table 7.2. Conccntration of organic contaminants in oysters, Crassostrea virginica, exposed to sediments firom Black Rock Harbor'. [co0mpounid ................. i [omoun ed men s a o dry wt.1 dr wt. Siufficient evidence as Benz(a)anthracene 695 -,3450 Benzo(a)pyrene 881 3160 0.20 0.02 0.06 Benzfluoranthene 364 5970 lndeno(I.2,3-cd)pyrene 222 1 Dibenz(a.h)anthracene 1 9 9 I i_ H-exachlorobenzene 0.21 Chlordanes 100 Limited evidence as carcinogens Chry-sene 1260 4450 10. 218 ...i............................... 2 Inadequate evidence as carcinogens Benzo(e)pyrenc 264 2880 0.09 Fluorene 42 635 0.07 P-ienanthrene '5 4020 0 14 [Perylene 17 i 504 0.03 Benz(g,h,i)perylene 37 Coronene 1.3 No evidence as carcino-ens Anthracene 191 1330 0.14 1 lluoranthene 1777 5800 0.31 Promoters DDT and metabolites 1183 PCBs (Aroclor 1254) 1143 Pyrene 2950 0.16 0.41 aData from Gardner et al. ( 199 1) Crassostrea virginica with exposure to sediments from Black Rock Harbor (Long Island Sound, USA; Table 7.2). As information continues to be gathered on the relationship between shellfish diseases and contaminant accumulation and transformation, the role of contaminants in disease processes should be elucidated.
(ON VA'MINA Ij1ON 1: FlF S ý\\Nr) MNHIN 10R I NG OIF \\M*R I NE SII(1 1-LFIS II 13 CI-I..I.UilAR AND PI-1ISiCoI..oCGICAI. RESPONSES Cellular and physiological responses of bivalve molluscs to contaminants provide the basis of link-ing observations of contaminant chemistry with observed disruption in physiological function. Numerous indicators of cell function have been proposed as biomarkers of cell damage in response to contaminant exposure. Alterations in lysosomal structure and function are consistent with observa-tions of degeneration of digestive gland epithelium, atrophy of digestive tubules, and degeneration of reproductive tissues (Lowe et al., 1981; Moore and Clarke, 1982; Couch. 1984; Pipe and Moore, 1985; Lowe and Pipe, 1985, 1986, 1987: Moore et al., 1989). These observations have been linked in bivalve mollIscs with exposure to high levels of I ipophilI ic contaminants in the mussel N'f vtih/s edidis (Lowe, 1988: McDowell et al., 1999). Lowe and Pipe (1987) suggested that the reallocation of energy reserves fiomn resorbed oocytes to storage cells might serve as a resistance strategy to survive the effects of hydrocarbon exposure. Ringwood et al. (1999) observed alterations in lysosomnal function and glutathione concentrations in juvenile oysters (Crassostrea virginica) exposed to contaminated sediments with a mixture of trace metals. Responses of cell function varied signifi-cantly with contaminant loading and the data agreed well with other estimates of sediment toxic-ity (Long et al., 1995). Other indicators of contaminant effects in bivalve molluscs show promise as monitoring tools or biomarkers of exposure to chemical contami-nants and biochemical or cellular damage. These include the presence of single-strand breaks or alkaline labile areas in the DNA complement of individual cells (Shugart et al., 1989) and the pres-ence of stress proteins within the cell (Hightower., 1993). Many compounds have been shown to have genotoxic effects in marine organisms including methyl methane sulfonate (Nacci and Jackim, 1989) and N-methyl-N'-nitro-N-nitrosoguanidine (Nacci et al., 1992). In each case, significant increases in DNA breakage occurred in a dose dependent fashion. Cells have the capability of repairing damage to the DNA molecule (Martinelli et al., 1989), thus, providing a potential means of timing the exposure event and subsequent recovery. Stress proteins are a group of proteins that are routinely synthesized within cells in response to exposure of the cell to a \\vide variety of physical and chemical conditions (l~ightower, 1993). Some stress proteins are produced in general response to a wide range of stressors, whereas other stress pro-teins are unique to a specific chemical or physical stress (Bradley, 1993). A stress protein "finger-print" can be measured and used as a marker of contaminant effects in the environment (Randall et al.. 1989). At the present time, heat shock protein 60 (Sanders et al., 1991 ) and heat shock protein 70 (Steinert and Pickwell, 1993) appear to be appro-priate as biomarkers of environmental stressors in marine bivalves. Recent studies by Clayton (1996), however, caution that the site of collection, season, and tissues samnpled need to be carefully considered in order for heat shock proteins to be used as biomarkers of contaminant effects. In addition to acting as indicators of contami-nant exposure, the presence of these biomarkers may be indicative of sublethal damage to the organism that may have consequences for individu-al survival. reproduction. and population processes. The implications of genotoxic agents in terms of damaged DNA are obvious with respect to the overall impact on the transcription and replication of the DNA molecule. Sanders et al. (1991) observed the accumulation of heat shock protein 60 (hsp 60) in conjiunction with a decrease in scope for growth (SFG) measurements in,1v1ilus edulis exposed to sublethal concentrations of copper. Accumulation of hsp 60 was a more sensitive indi-cator of copper exposure than reductions in bioen-ergetics as measured by scope for growth. Alterations in growth rates of bivalve molluscs occur as a result of reductions in feeding rates, higher respiratory metabolism, and reduced diges-tive efficiencies. Reductions in physiological mea-surements (e.g., respiration rates, carbon turnover, and scope for growth) have correlated with reduced growth rates measured for bivalve populations from contaminated habitats (Gilfillan et al., 1976; Gilfillan and Vandermeulen, 1978; Capuzzo and Sasner, 1977). Alterations in bioenergetics and growth of bivalve molluscs following exposure to petroleum hydrocarbons appear to be related to tis-sue burdens of specific aromatic compounds (Gilfillan et al., 1977; Widdows et al.. 1982, 1987; Donkin et al., 1990). Widdows et al. (1982) demonstrated a negative correlation between
124 FA:O\\V ',d cellular and physiological stress indices (lysosonial properties and scope for growth) and tissue concen-trations of aromatic hydrocarbons with long-term exposure of Al/Vilus edulis to low concentrations of North Sea crude oil. Recovery of mussels follow-ing long-term exposure to low concentrations of diesel oil coincided with deputation of aromatic hydrocarbons (Widdows et al., 1987). Donkin et al. (1990) suggested that reductions in scope for growth in,V. edulis were related to the accumula-tion of two-and three-ring aromatic hydrocarbons, as these compounds induced a narcotizing effect on ciliary feeding mechanisms.' Diminished scope for growth, alterations in lysosomal function, and decreased reproductive effort appear to be general responses to contami-nant exposure and may be indicative of general reduction in physiological conditions. The response of the turkey wing Mussel (Arca zebra) to contami-nants along a gradient in the waters surrounding Bermuda included reduced feeding rates and increases in metabolic expenditures associated with significant accumulation of lead, tri-and di-butyltin, petroleum hydrocarbons and their polar oxyguenated derivatives, and PCBs (Widdows et al., 1990). Mussels collected along the same gradient showed changes in biochemical composition, espe-cially in the ratio of neutral to polar lipids and car-bohydrate content (Leavitt et al., 1990). A'lyiihis editis transplanted to New Bedford Harbor (Buzzards Bay, MA) showed reduced reproductive effort and increased degeneration and premature resorption of oocytes, coincident with high body burdens of PCBs and PAHs (Table 7.3, McDowell et al., 1999). The greatest differences in condition index and lipid reserves of mussels were observed during the pre-spawning period, consis-tent with the accumulation and utilization of lipid reserves for reproductive development. Following spawning no differences in condition index were evident and lipid reserves were diminished to mini-mum levels. Resident populations of mussels from New Bedford Harbor also showed extensive signs of gonad degeneration. Table 7.3. Condition indices and reproductive effort of mussels..1,vtiihis edulis, transplanted to New Bedford Harbor. and reference sites. station M.. aximium Rep-oductive I Condition Index Eflbrt Pre-spawning % RE/Total mg Dry Wt./Shell Energyb \\Volumea Nantucket 335+.. Sound 0.88 Cleveland [ C340+20 0.71 Ledge New Bedford 230+15 0.34 Harbor ')ata from McDowell Captzzo (1996); Mean I S.E. "Calculated fiom mean values from eight individual animals at each site. POPULATION LEVEL RESPONSES. The r-oot problem is that we - and this includes ecotoxicologists and ecologists - still do not know enough about ecological systems to be able to identif, what it is we want to protect about them and hence, t/,hat we should be measuring. Clearlv, this is most acute at community and ecosystem levels. -Peter-Calow, 1994 Chronic exposure to chemical contaminants can cause alterations in reproductive and develop-mental potential of populations of marine organ-isms, resulting in possible changes in population structure and dynamics. It is difficult to ascertain, however, the relationship between chronic respons-esof organisms to contaminants and large-scale alterations in the functioning of marine ecosystems or the sustainable yield of harvestable species. Cairns (1983) argued that our ability to detect toxic effects at higher levels of biological organization is limited by the lack of reliable predictive tests at population, conmmunity, and ecosystem levels. Much research effort is needed in these areas before environmental hazards as a result of contaminant inputs can be adequately addressed.
CONIA kN1IN.V NO FFE([ .'[S AND ONITiOIINCi OF-MAKINE S1IIFLIFI:SHlI~ Koojiman and Metz ( 1984) suggested that the sub-lethal effects of contaminant exposure should be interpreted in light of the survival probabilities and reproductive success of populations, thus bridging the gap between individual and population responses. Although many indices have been proposed for evaluation of chronic responses of organisms to contaminants, few have been linked to the survival potential of the individual organism or the repro-ductive potential of the population (McIntyre and Pearce, 1980). Experimental studies directed at determining effects on energy metabolism or effects that influence growth and reproduction would be most appropriate for linking effects at higher levels of organization. When investigating biological effects of contaminants, many variables must be recognized and assessed. Differential sen-sitivity off different species of organisms, various life history stages, and species froom different habi-tats may be related to contaminant bioavailability, capacity for contaminant biotranslformation, and the metabolic consequences of contaminant expo-sure. The increased sensitivity of early develop-mental stages and the seasonal difterences in the responses of adult animals may be related to stage-specific or seasonal dependency on particular metabolic processes (e.g., storage and mobilization of energy reserves, hormonal processes), with the result of altering developmental and reproductive success (Capuzzo. 1987). Reproductive success and development of an organism may be affected by contaminant exposure by: I. deposition of contaminants in gametes and developing embryos;
- 2.
lysosomal dysfunction associated with oocyte resorption;
- 3. interference with feeding mechanisms, such that exposure mimics starvation responses;
- 4.
failure to incorporate sufficient yolk in oocytes;
- 5.
morphological abnormalities during embryoge-nesis resulting from failure of morphological systems to develop properly;
- 6.
limited capacity of developmental stages to metabolize or depurate contaminants; and
- 7.
limited capacity of early developmental stages and reproducing adults to draw on excess ener-gy reserves (Capuzzo et al., 1988). Thus, responses can be categorized as interfering with energetic processes (3, 4, and 7), biosynthetic processes (4), and structural development (2, 5) in addition to contaminant accumulation and depura-tion (I, 6). Alterations in bioenergetics linked with observations of" reduced fecundity and viability of larvae, abnormalities in gamete and embryological development, and reduced reproductive success provide a strong empirical basis for examination of population responses. Incorporation of these responses in demographic models may lead to new insights on adaptations of specific life history stages to contaminant perturbations and the popula-tion consequences of stage-or age-specific effects of contaminants. Reduced scope for growth and decreased fecundity in mussels exposed to high levels of PCBs in New Bedford suggest population consequences (McDowell et al., 1999). For species that have planktonic life history stages, resettle-ment in highly contaminated areas may obscure demographic changes due to impaired bioenergetics. The population dynamics of bivalve species have received considerable scientific attention due to the importance of many bivalves as commercially harvested fisheries. Demographic models have been developed to examine the importance of spe-cific life history characteristics on population pro-cesses. Such models include: (1) analysis of the sensitivity of population growth rate to life cycle perturbation, (2) life table response experiments, and (3) population projection and prediction (Caswell, 1989ab). In addition to quantifying the impact of fishing pressure on bivalve populations, demographic models have been used to assess the importance of environmental perturbations (e.g., disease, contaminant effects, etc.) on bivalve physi-ology and population dynamics (Weinberg et al., 1997). Ayers (1956) suggested that larval mortality was one of the most important considerations in monitoring the population dynamics of the soft-shell clam. yl~a arenaria, an observation consistent with numerous studies of bivalve species (Brousseau, 1978; Brousseau et al., 1982; Weinberg et al., 1986). Brousseau et al. (1982) suggested that larval mortality could be further separated into mortality that occurred during (a) fertilization, (b) the free-swimming larval phase, or (c) early post-larval attachment (see also Brousseau, Chapter 6). Using sensitivity analysis, Brousseau and Baglivo (1984) addressed changes in the population growth
1 2 6 I \\X'I I.ho o,[ rate attributable to changes in settlement rates of larvae and in age-specific fecundity and survivor-ship rates of the soft-shell clam. They concluded that population growth rate was insensitive to abso-lute values in egg production and most sensitive to changes in egg and larval viability which con-tribute to the success of larval settlement. Malinowski and Whitlatch (1988) further docu-mented that population growth rates were two to three orders of magnitude more sensitive to changes in survivorship in larval and juvenile stages of the life cycle than proportional changes in either survivorship or fecundity in adult size classes. Since sensitivity analysis has identified that the larval stage is the most critical life history stage controlling population growth rate, experiments and field collections designed to quantify the vital rates associated with larval survival and viability are needed. Processes 'elated to the allocation of energy to developing eggs and larvae that influence not just numbers of developing eggs but size and quality of energy reserves for larval development are especially important. These data can then be applied to a demographic model to ascertain how perturbations in larval viability may affect popula-tion growth and development. Any factor (e.g., dis-ease, contaminant exposure, etc.) that alters the allocation of energy reserves to developing eggs and larvae may result in a reduction in larval via-bility and post-settlement success. Among the classes of contaminants that are prevalent in Boston Harbor and Massachusetts and Cape Cod Bays that may specifically alter energetic and reproductive processes in bivalve molluscs are the chlorinated hydrocarbons (including PCBs and pes-ticides) and polycyclic aromatic hydrocarbons. Population models could be used to differentiate the effects of contaminants, fishing pressure and habitat alteration on population structure of bivalve molluscs. Studies have recently been completed in Massachusetts Bay to examine the effects of poly-cyclic aromatic hydrocarbons and chlorinated hydrocarbons on population processes in the soft-shell clam, MI arenaria (McDowell and Shea, 1997). Contaminants were detected in clam tissues and sediments collected along a sediment gradient of polycyclic aromatic hydrocarbon contamination in Boston Harbor and Massachusetts and Cape Cod Bays (300 to 66,000 ng per g dry weight), but the bioavailability' of specific compounds varied at dif-ferent sites. Estimates of the fraction of contaminants available in porewater and sediments for equilibrium partitioning (AEP) provided the best predictor of relative bioavailability. The reproductive cycle of clam populations from the five sites varied with respect to the timing and extent of the spawning season but not with respect to the number of developing oocytes during a spawning event. Both female and male clams from the reference sites had advanced stages of gamete development during tile late spring and spawning continued through the early fall. The large relative size of the digestive gland-gonad complex and accumulated lipid provided sufficient energy for this extended reproductive season. Populations from the upper Massachusetts Bay sites (Fort Point Channel, Saugus River and Neponset River) did not spawn until mid-summer and spawning occurred for only a short period of time. Asynchrony in gamete development between males and females was niot observed at any of the five sites.'In addition to an abbreviated spawning season, clam populations from the contaminated sites also showed a high prevalence of gonadal inflammation (cell proliferation) that was signifi-cantly different (p<O.O01) from reference popula-tions especially during tile late fall to early winter (September to December). At the most contaminated site (Fort Point Channel), levels of hematopoietic neoplasia also reached 100% in December 1995 (McDowell and Shea, 1997). Population growth rates were determined for all populations using a deterministic matrix model. Trends in population growth rates were not directly related to contaminant concentrations at each site, as other site features such as predator abundance and hydrographic features had strong influences on recruitment success (McDowell and Shea, 1997). The deterministic model was relatively insensitive to the differences in reproductive physiology related to contaminant exposure. High inter-annual and inter-site variability in recruitment patterns may mask contaminant effects on population processes. Stochastic models such as those developed by Ripley and Caswell (1996) may add more insights on variability in' population structure as a result of the interactive effect of contaminants and other habitat features.
CONTAM INAvto 110\\
- (r.xt)S A N tDONt'1'0ýIN G 01: MA..R INi:ttn.L s I
SUNI\\IAIR\\ AND CONCi.tSIOsNS This chapter addresses the effects of contami-nants on shellfish populations in coastal habitats. Accumulation of contaminants in shallow-water benthic habitats has led to contamination of shell-fish resources at many locations along the New England coastline, especially in habitats adjacent to urban areas. Contaminated sediments have con-tributed to habitat degradation and have resulted in restricted access to shellfish resources. In spite of these problems, shellfish populations in contami-nated habitats may be quite abundant even though reduced reproductive effort and high disease preva-lence are also observed. Areas closed to fishing such as those studied in the more urban sections of Massachusetts Bay show populations with a wider distribution of size and age classes than those sites that are routinely harvested (Brousseau, Chapter 6). When moderately contaminated areas are open to periodic harvesting for relaying contaminated stocks, a discontinuity in size classes is observed (Brousseau, Chapter 6). The sporadic recruitment success of bivalve populations at shallow-water benthic sites appears to be the dominant feature influencing population size and age structure. Recruitment of newly settled bivalves to contami-nated sites even when reproductive effort of adult shellfish at those sites is reduced will balance the losses related to disease and loss of reproductive potential. The comparison of contaminant effects and overexploitation of shellfish populations is dif-ficult to make as fishing mortality may represent one of the major losses to population abundance in uncontaminated habitats. For shellfish stocks that. are overexploited even in uncontaminated.habitats sporadic recruitment patterns of many bivalve mol-luscs may require long periods between harvesting to compensate for the discontinuity in size classes. In contrast, the restriction of shellfish harvests in contaminated habitats may allow high population abundance of bivalve molluscs even though chronic sublethal toxic effects are common. Thus, the rela-tive importance of contamination and overfishing on bivalve populations is difficult to assess, even at the local level. LITERATURE CITED Anderson, R.S. 1978. Benzo(a)pyrene metabolism in the American oyster Crassostrea,irginica. EPA Ecol. Res. Ser. Monogr. EPA-600/3-78-009. Anderson. R.S. 1985. Metabolism ofta model environmental carcino-gen bv bivalve molluscs. Mar. EInviron. Res. 17: 137-140. Anderson, R.S and I.E. Doos. 1983. Activation ol inmainalian car-cinogens to bacterial Inutaicns by. iicrosomal enzymes from a pelecypod mollusc. Mutat. Res. 16:247-256. Arinstrong, P.B., GM. Hanson andMCI I. F audIcc. 1976. Minor cle-ments in sediments ofhGreat Bay estuary, New Hampshire. Environ. Geol. 1:207-214, Ayers. J.C. 1956. Population dtnamics of the marine clam, Mya are- . nuria. Liniol. Occanoer. 1.:6-34. Bayne. B.L.. R.F. Addison. JAM. Capuezo I'. K Clarke.I. S. Grav MN. Moore and R.M. 'Warvick. 1988. An overview otfthe GEEP workshop. Mar. Ecol. Pro" Ser 46 235-243. Bayne, B.L., D.A. Brown, K. Burns, I) R Dixon, A. Ivanovici, [). Livingstone, D.M. Lowe, M.N. Moore, AR.D. Stebbing and J. Widdows. 1985. The EtTects of Stress and Pollution on Marine Animals. Praeger, New York 381 pp. Br3lly. 111)P 1993. Are tile stress, ptoteins indicators of extposure or effect? Mar Environ. Res. 35:85-8. Brousseau, D.J. 1978. Population dynamics of the sbft-shell clam l,'/a arenaria" Mlar. Biol. 50:63-71 Brousseau, DT. and J.A. laglivo. !984. Sensitivity of the population growth late to changes in liice history parmietlrs: its appli-cation to.4t4cW W1147 n*Iir1 Mollusca:Pelecypoda). Fish tiul l 82:537-541. Brousseau, DJ., J.A. Baglivo and G.E. Lang, Jr. 1982. Estimation of equilibrium settlement rates for benthic marine invertebrates: its application to Mya arenaria (Mollusca:Pelecypoda). Fish. Bull. 80:642-648. Butler, P.A. 1973. Residue in fish, wildlife and estuaries. Organochlorinc residues in estuarine ito1llusks, 1965-72. National Pesticide Monitoring 'rograin. Pest. Moniit..1. 6:238-246.- Cairns.i. 1983. Are single species tests alone aidequate or estimating environmental hazaid? IHvdrobiologia. 100: 17-57. Calow. P. 1994. Ecotoxicology: What are we trying to protect? Environ. Toxicol. Chem. 13:15 49 Capuzzo. J.IN. 1981. Predicting pollution eff'ects in the marine envi-ronment. Oceanus 24( 1 1:2i-33. Capuzzo, JiMl. 1987, Biological elliects ol petroleum hydrocarbons: Assessments Iltot experimncttal results. It: l.ong-term Environmental Effects of tO ttshore Oil and Gas Development. D.F. Boesch and N.N. Rabalais. (eds.). Elsevier Applied Science, London. pp. 3,43-410. Capuzzo, J. M. and F. E. Anderson. 1973. The use of modern chromi-um accumulations to determine estuarine sedimentation rates. Mar. Geol. 14:225-235. Capuzzo, J. M. and J. J. Sasner. 1977. The effect of'chromium on fil-tration rates and inetabolic'activity of/Myti/ts ecilis L.. and AM/ya arenaria L. In: Physiological Responses of Marine Biota to Pollutants. F. J. Vernberg, A. Calabrese, F. P. Ihurberg and W. B. Vernberg (eds.). Academic Press, New York. Pp. 225-237. Capuzzo. J. M. M.N. Moore and J. Widdows. 1988. Effects of toxic chemicals in the marine environment: Predictions of impacts from laboratory studies. Aquat. Toxicol. 11:303-311. Caswell, H. 1989a. Matrix Population Models. Sinauer Associates, Inc. Publishers. Sunderland, MA. 328 PP. Caswell, 11. 1989b. -The analysis of life table response experiments. I. Decomposition of treatment effects on population gro,,ýwth rate. Ecol. Model. 46:221-237. Clayton, M 1996. Lipoproteins and heat Shock Proteins as Measures of Reproductive Physiology in the Soft Shell Clam Wya arenaria. Ph.D. Dissertation, Massachusetts Institute ol Technology/Woods Hole Oceanographic Institution Joint Program, Woods Hole, MA. Couch, J.A. 1984. Atrophy ofdiverticular epithelium as an indicator of environmental, irritants in the oyster, Crassostrea virginica. Mar. Environ. Res. 14:525-526.
12'8 \\,-[ot,,,.,iit Di'l: ro. f.M.,..11). Mahony I).J. lHansen. KJ. Scott. IM.B. [
- icks, S.M. Mayr and M.S. Redmnond 1990.
Toxicity of cadnitum in sediments: The role of acid volatile sulfide. Environ. loxicol. Cheitn. 11.1487-1502, Di-oro, L.M., C.S. Zarba. DJ Hlansen, W.J. BeFiy, R.C. Swartz, C.F Cowen. S.1. Pavlou. F-.E. Allen N.A Thomas and P.R Paquin. 191) 1. 'Icchnlical basis loi cstabl ishng sedim ent qual ity critcrii for nonionic chemicals using equilibrium Partitioning. Fnviron. Toxicol. Chem. 12:1541-1583. Donkin, P.. I. Widdows. S.V Evans, CM. Worrall and M. Carr 1990. Qtlantitati c Structure-activity rilationships for tile eflect of hydrophobic chemicals on rate of feccding by imussels (TVht/us ed/iis). AqUiat. Toxicol 14:277-294. Farrington, I.W., El.D. Goldhbetg RVW Risebrough, J.H. Martin and V.1. lBowei. 1983. U.S. "Mussel Watch" 1976-1978: An overview of the trace metal, DDEl, PCB, hy-drocarbon and artificial radionuclide data. Environ. Sci Technol. 17:490-496. Fisher, S.W. 1995. M/lechanisms of Bioaccumulation in Aquatic Systiemas. Rev: Etnviron. Contain. -loxicol 142 87-11 7. Garcia-Mairtinez, P. and D.R. Livingstone. 1995. Benzo[alpyrene dione stimulated oxyradical production by microsories of diges-tive cland of the coinmmon mussel -l,/tilus edid's I. Mar. En viroil. Res. 39:185-189. Gardner, C.R., P1P'. Yevich, I.C. lHarshbargel a-nd A.R. Malcoim. 1991. Carcinocenicity of Black Rock Harbor sediment to the Eastern oy.ster and troplhic transfer o0 Black Rock FFarbor carcinogens from the blue muiussel to the winter flounder. Environ. Health Perspect 90:53-66. Gilfillan, E.S. and J.H. Vandermetilen. 1978. Alterations in grow-th and physiology of solt shell clams, Myva arenaria: Chronically oiled with Bunker C f-oin Chedabucto Bay, Nova Scotia, 1970-
- 76. J. iFish. Rcs. Board Can. 35:630-636.
Gilfillan. 13 S, 1). Mayo, S. llanson, D Donovan and L.C..siang. 1976. Reduction in carbon flux inIya ar-ntrt catsed by a spill of No. 6 fuel oii. Mar. Biol 37 115 -123 Gilfillan, E.S., D.W. Mayo, D.S. Page, D. Donovan and S. Hanson. 1977. Eftects of vary-ing concentrations of petroleum hydrocar-bons in sediments on carbon flax in Wya arenaria. In: Physiological Responses of Marine Biota to Pollutants. E.J. Vernberg. A. Calabtese, I..t Thutberg and W.B. Vernberg (els.). Academic Press, Nov York. Pp. 299-314. Goldberg, ED. (ed). 1980. Remote sensing and problems of the hydrosphere; a foccus for future research. Proceedings of a work-Ing group meetintgF held at New Orleans, Louisiana, Mav 9-11, 1979. National Aeronautics and Space Administration, Scientific and Technical Information Office, Springfield, VA. NASA con-ference publication no. 2132. 30 pp.. Goldberg-E.D., M. Koide, V. Hodge, A.R. Flegal and J. Martin. 1983. U.S. Mussel Watch: 1977-78 results on trace metals and radionu-clides. Est. Coast. ShelfSci. 16:69-93. Hlauge, P. 1988. Troubled waters: Report on the Environmental Iealth of Casco Bay. Conservation Law Foundation, Boston, MA. 71 pp. Hightower, L.E. 1993. A brief" perspective on the heat-shock response and stress proteins. Mar. Environ. Res. 35:79-83. Johnson, A.C., P.1F. larsen, D.F. Gadbois and A.W. Huttason. 1985. The distribution of polycyclic aromatic hydrocarbons in the surfi-cial sediments of Penobscot Bay (Maine, USA) in relation to pos-sible sources and to other sites worldwide. Mar. Fnviron. Res. 15: 1-16. Jones, S.H., M. Chase, J. Sowles, W. Robinson, P. Hennigar, G. Harding, D. Taylor, P. Wells, J. Pederson, K Coombs, K. Freeman and I... Mucklow. 1995. The First Five Years of Gulfwatch, 1991-1995: A Review of the Program and Results. Report of the Monitoring Committee of the Gulf of Maine Cotincil on the Marine Environment. Gulf of Maine Council. 166 PP. Kennicutt, M.C. I1, T.L. Wade, B.J. Presley, A.G. Requejo, .- I..Brooks atid G.J. IDeniotux 1994. Setitineni c0iiita:tttlltits in Casco Bay, Maine: Inventories, sources, and potential lor biologi-cal impact. Environ. Sci. Technol. 28: 1-15 Knezovich. J.P.. N-I Laston and F.L. I larrison. 1 98S. It vivo metiabolisit of'aromatic amties by the bay mnssel, -'Iyti/tls ct/ti/is. Mar Eniviron Res 24:89-91. Kooji ttant S.iL..M. and.1 AL Mctz. 1984. Ol thie dyntaniics ot" chemically stressed populations: The deduction oif popnlation consequences from effects oii individuals. Ecotoxicol. I:in-viron. Safety 8:254-274. Kurelec, 13 and S. Krca. 1987 Metabolic activatioti 01 2-inoIllut1o-rene. 2-acetylamtrio-Illuorene and N-hydroxyacetyslainittohl1Lo-eric to bacterial itutagens with mussel (Mytilus galloprovintcialis) and carp (t.ypt titus crI7)io) suibcel ltlar prepara-tions. Comp. Biocheti. Physiol 88C: 171-177. Kurelec, B., S. Britvic and R.K. Zahn 1985. The activation of aro-matic amnines in some marine invertebrates. Mar. Enviroti. Res. 17:141-144. KrelCec. B.. M. Chacko and R C, Gupta. 1988. Postlabeliutg analysis l' carciniogcn-DNA adducts in mussel, Myti/us ia//oproriiiia/is. Mar Environ* Res 24 317-320. Larsen; P.F. 1992. Marine Environmental Qtmalitv in tile Gulf of Maine: A Review. Rev. Aquat. Sci. 6:67-87. Larsen, P.F._ I).F Cadbois and A.C.- ohnson. 1986. Distributiont of polycylic aromatic iydrocarbons ill surficial sediments of the deeper waters of th Gulf of Mainae NIar. Pollut. Bull. 18:231-244. Leavitt, D.F., B.A. Lancaster, A.S. Lancaster and J. NMcDowNell Capuzzo. 1990. Changes in the biochemical composition tfa subtropical bivalve, Area Zebra, ii response to contaminant gradi- " ents in Bermuda. J. Exp Mat. Biol F. col. 138:85-98. Livinigstorte, D.R. and S.V. Faria. 1984 "'[issue and subcelltular distri-btitioni rif nzvyl act sIties r'lI i dt 'CClttictlion oxyetnasc and benzolalpyrene metabolism ill tlie co1tlin mnussel 11t1its edtdis L. Sci. Tot. Einviron. 39:209-235 Livingstone, DR., P. Garcia-Martinez, X. Michel, J.F. Narbonne, S O'llara, D. Ribera and GW. Winston. 1990. Oxyradical produc-tion as a pollution mediated mechanism of toxicity in the com-mon mussel Alvi/us editis L. and other molluscs. Functional IEcolocv 4:415-424. Long, E. R., D.D. MacDonald, S. L. Siith and FD. Calder. 1995. Incidence of adverse biological eflects within ratnges of chemical in marine and estuarine sediments. Envir. Manacement 19:81-97. lowe, D.M. 1988. Alterations in Cellular structure of 04lytihs edttis resulting from exposure to environmental contaminants under field and experimental conditions. Mar. Ecol. Proc. Ser. 46:91-100. Lowe, D.M. and R.K. Pipe. 1985. Cellular responses in the mussel -V/ytilus editis following exposure to diesel oil emulsions: Reproductive and nutrient storage cells. Mar. Environ. Res. 17:234-237. Lowe, D.M. and R.K. Pipe. 1986. Hydrocarbon exposure in mussels: A quantitative study on the responses in the reproductive and nutrient storage cell systems. Aquat Toxicol. 8:265-272. Lowe, D.M. and RK. Pipe. 1987. Mortality and quantitative aspects of storage cell utilization in mussels, Wy)i/tts ecrutis, following exposure to diesel oil hydrocarbons. Mar Environ. Res. 22:243-251. Lowe, D.M., M.N. Nloore and KR. Clarke. 1981. Effects ofoil oti digestive cells in mussels: Quantitative alterations in cellular and lysosomal structure. Aouat. Toxicol. 1:213-216. Luoma. SN. and N.S. Fisher. 1997. Uncertainties in assessing coni-taminant exposure from sediments. In: Ecological Risk Assessment of Contaminated Sediments, C.G. Ingersoll, T. Dillon, and G.R. Biddinger (Eds.), SETAC Spec. Publ. Series, Pensacola, FL, pp. 211-237. Luoma, S.N., M. Hornberger, D.J. Cain, C. Brown, B.GC Lee and EV. Axtmann. 1997. Fate, bioavailability and effects of metals in
C NTAtXtiINA[ IOtN EFFU r.rS ANtD)7 tION II"Ol N G nr: Nt..xfiI' Stitii I 7.I f 1 9 rivers and estuarics: P, ole of Sediments. ProceediiIgs of the U.S Geological Survey Sediment Workshop, Feb. 4-7. 1997. Mael )ona Id 1) A 1 991. Status and Trends in Concentrations of Selected Contaminants in Boston I larbor Sediments and Biota. NOAA T-chnical MCeilorantdum NOS OMA 56 Seattle. WA Malinowski. S. and R.B Whitlatch. 1988. A theoretical evaluationi or shellfish resource mana'er ent. J. Shelitish. Res. 7:95-i t). Martinell i, R. F_ 1I1'. Knezovich and F. I larrison I )89, Radiation-induced DNA-strand breakage and repair in the marine poly-chaete. Veanthes arenaceodentata. Mar. Environ. Res 28: 329-332' Mayer. L.M. and L.K. Fink. Jr. 1980. Granulomnetric dependence of chromium accumulation in estuarine sediments in Maine Estuar. Coast. Mar. Sci. 11:491-503. McDowell Capuzzo, J. 1995. Environiental indicators of toxic chein-ical contaminants tl the Gulf of Maine. pp 187-204. In: National Research Council (ed.) Improving Interactions Between Coastal Science and Policy, Proceedings of the Gulf of Maine Sy'mposiumt National Acadetmy Press_.Washington DC. McDowell Capuzzo,.I 1996. Biological cflects of containinants on shellfish populations in coastal habitats: A case history of New Bedford, MA. In: IThe Northeast Shelf: Assessment, Sustaiimability, and Manigement. Butterworth-lI tiiernann. M c Jowell J. 1997. Bi3ological effets of to-, Ic chemical contami-nants it the Gull o' lMaine. itn ( T. Wallace. and E.F. Braasch (Eds.). Proecedings of thc Gulf of Mlaine Ecosystem Dvnattics, A Scientific Symposium and workshop. Regional Association lbr Research on the Gulfof Maine, RARGOM Report 97-1. McDowell-J.E. and D. Shea. 1997. Population Processes of ?1mo are-ntaria from Contaminated Habitats in Massachusetts Bays. Final Report to the Massachusetts Bays Program. Boston. MA. McDowell, J.E., B.A. Lancastert D.F. Leavitt. P. Rantantaki and B. Riplcy. 1999. lhe ellcts ol'lipophilie organic contanitlttts on reproductive physiology and disease processes in marine bivalve molluscs. Limnol. Oceanogr. 43(2):903-909. McGroddy, S.E. and J.W. Farrington. 1995. Sediment porewater parti-tioning of polycyclic aromatic hydrocarbons in three cores from Boston Harbor. Massachusetts. Environ. Sci. Technol. 29:1542-1550. Mclntyre, AD. and J.B. Pearce teds.l 1980. Biological Ffllects of NMIarie Poll uttion and the Problems of Mionitoring. Rapp. P-V Reunt. Cons, lit. Explor Mer 179:1-346. MenItzie-Cura & Associates, Inc. 1991. Sources and Loadings of Pollutants to the Massachusetts Bays. Report to the Massachusetts Bays Program, MBP-91-01, Boston, MA. Mix, M.C. 1986. Cancerous diseases in aquatic anintals and their association with environmental pollutants: A critical literature review. Mar. Environ. Res. 20:1-141. Mix, NMC. 1988. Shellfish diseases in relation to toxic chemicals. AQuat. loxicol. 11:29-42. Moore. M.N. and K.R. Clarke. 1982. Use of microstereology and quantitative cytochemistry to determine the effects of crude oil-derived aromatic hydrocarbons on lysosmoal structure and func-tion in a marine bivalve mollusc, Mm-/ilus e/u/lis. Histochem. J. 14:713-718. Moore, MN., DBR i vingstone and J. Widdows. 1989. Hydrocarbons in marine molluscs: Biological effects and ecological conse-qutentces. Pages 291-328 in U. Varanasi, editor. Metabolism of polveyclic aromatic hydrocarbons in the aquatic environment. CRC Press, Boca Raton, FL. Moore, M.N., D.R. Livingstone, P. Donkin, B.L. Bayne, J. Widdows and D.M. Lowe. 1980. Mixed function oxygenase and xenobiotic detoxication/toxication systems in bivalve molluscs. Helgol. Wiss. Meeresunters. 33:278-291. Nacci, D. and E. Jackim. 1989. Using the DNA alkaline unwinding assay to detect DNA damage in laboratory and environmentally exposed cells and tissues. Mar. Environ. Res. 28:333-337. Nacci, D., S. Nelson, W. Nelson and E. Jackim. 1992. Application of thie DNA alkaline Luwitivad ing assay to detect DNA strand breaks in marine bivalves. Mar. Environ. Res. 33:83-100. NOAA INational Oceanic and Atmospheric Administration). 1989. A S1uitt tt ar\\ of Data ott Tissue Contamination Front tile First Thrce Years ( 1986-1988) oftthe Mussel Watch Project. NOAA Technical Memorandum NOS OMA 49, Ocean Assessment [)i\\ ision, Offi~ce o1' Oceaniography anld Mvarine Assessment-National Oceanic and Atmospheric Administration. U.S. Department of Commerce, Rockville, MD. 22 pp. plus appen-dices. NOAA (National Oceanic and Atmospheric Administration). 1991. Second Summary of Data on Chemical Contaminants in Sediments From the National Status and Trends Program. NOAA Technical Memnorandum NOS OMA 59, Rockville, MD. NRC, (National Research Council). 1980. The International Mussel Watch. National Academy Press, Washington. DJC. 248 pp. O'Connor, T'. 1998. Chemical contaminants in oysters and mussels. NOAA's State ofthe Coast Report, NOAA, Silver Spring, MD. Pipe, R.K. and MN. NMore. 1N85. The ultrastructural localization of acid hydrolases in developing oocytes of Mytilus edulis. Histochem. J 17:939-949. Randall. R., Fl. Lee and 13. Sanders. 1989. The stress proteins response as a measure f pollhitant stress il tile iititnal cClait1 1ofcom twistita. In: Proceedings, Oceans 89: the Global Occan, Volume 2: Ocean Pollution. Ringwood. All., BE. Conners, and C.J. Keppler. 1999. Cellular responses of oysters. Crassostrea 'irgnica, to metal-contaminated sediments. Mar. FEtviron. Res. 48427-437 Ripley.B.J. and H. Caswell. 1996. A theoretical analysis of the role of recruitment variability it structuring populations of the steamer clam. iOna -renarit. 24 th Annual Benthic Ecology NMectintgs, March 7-1 0, University of South Carolina, Columbia, SC. Sanders, B.M., L.S. Martin, WG Nelson, D.K. Phelps and W Welch. 1991. Relationship between accumulation of a 60 kDa stress tr(i-tein and scope-for-growth it tvuilus edulis exposed to a range of copper concentrations. %iar. Environ. Res. 31:81-97. Shea, D. 1988. Developing national sediment quality criteria: Equilibriutm partitioning ofcontaminants as a means of evaluatint sediment quality. Environ. Sci Technol. 22 1256-1261. Shuigart, L.R.. M.K. Gustitm. D.M. Laird and D.A, Dean. 1989. Susceptibility of B)NA i aquatic organisms to strand breakage: Effect of X-rays and gasimma radiation. Mar. Environ. Res. 28:339-343. Siidermann, C.J. 1979. Pollution-associated diseases and abnormali-ties of fish and shellfish: A review. Fish. Bull. 76: 717-749. Sowles. J., R. Crawford, J. Machell, G. Atkinson, P. Hennigar, S. Jones, J. Pederson and K. Coombs. 1992. Evaluation of GuIllvatch. 1991 Pilot Project of the Gulf of Maine Marine Environmental Monitoring Plan. The Gulf of Maine Council on the Marine Environment. 39 pp. plus appendices. Stegernan, J.J. 1985. Betiz6(a)pyrene oxidation and microsomal enzyme activity in the mussel (Mytilus editis) and other bivalve molluse species from the Western North Atlantic. Mar. Biol. 89:21-30. Stegeman, J.J. and J.J. Lech. 1991. Cytochrome P-450 monooxyge-nase systems is aquatic species: Carcinogen metabolism and biomarkers for carcinogen and pollutant exposure. Environ. Health Persiect. 90:1101-109. Steinert, S.A. and G.V. Pickwell. 1993. Induction of HSP70 proteins in mussels by ingestion of tributyltin. Mar. Environ. Res. 35:89-93. Valette-Silver. N.J. 1999. Preface, Special Issue: Using sediments and biota to assess coastal and estuarine contamination. Mar. Environ. Res. 48:265-267. Wang, W.X. and N.S. Fisher. 1997. Modeling metal bioavailability for marine mussels. Rev. Environ. Contain. "Txieol. 151:39-65 Wang, W.XK, N.S. Fisher and S.N. Luoma. 1996. Kinetic determina-tions of trace element bioaccumulation in the mussel Alsilius
130 I I.,o-sr0I. dehi/is. Mar. Fcol. Ser. 140:91-113. Wang. W.., S.B. Griscorn, and N.S. Fisher. 1997. Bioavailability of Cr (111) and Cr (VI) to marine mussels from solute and particulate pad aN's. 1:nviron. Sci "Ichnol 31:603-61 I Weinberg. 3I.R.. H. Ca_\\scl, and R.B. Whitlatch. 1986. Demographic i1 portaIcC 0l: ecological interactions: How Much do statistics tell us'? Mar Biol. 93:305-3 10. Weinberu..I R. IDT ILeavitt B.A. lancaster and J. McDowell Capuzzo. 1997, Ixperimental field studies with Alva areanria (Bivalvia) on lhe induction and effect of hematopoietic neoplasia. J. Invrte. Pathol. 69:183-194. Widdows, J., I. Donkin and S.V. Evans. 1987 Physiological responses of CA'liy/s eduhis during chronic oil exposure and recovery. Mar. Environ. Res, 23: i-32. Widdowss, J., K.A. Burns, N.R. Menon, D.S. Page and S. Soria. 1990. Measuremsent of physiological energetics (scope for growth) and chemical contaminants in mussels (Arca zebra) transplanted along a contornination gradient in Bermuda. J. Exp. Mar. Biol. Ecol 138:99-117. Widdows, J., T. Bakke, BI... Bayne, R Donkin, DR. Livingstone. D.M. Loowe, MIN. Moore, S.V. Evans and S.L. Moore. 1982. Responses of,'Ail/ts edhdis on exposure to the weater accomlrnTO-dated fraction of North Sea oil. Mar. Biol. 67:15-31.
BiOLOGN. A]. PERSPECIAVI"S ON 1.01111TK I ' I Chanter VIII Are We Overfishing the American Lobster? Some Biological Perspectives ROBERT S. STENECK University of M11laine Darling Marine Center WIalpole, M14E 04573 USA Note: The fbllowing contribution was written in 1996 before the 2000 assessment was completed by the Atlantic States Marine Fisheries Commission. My article reflected managenient positions and approaches prior to the new assessment, and it considered the ongoing diffi-culty in determining whether lobster stocks are over-fished. It is possible that several specific concerns iden-tified in my paper will be addressed in that assessmnent. However, this paper predates the ASMFC assessment process and thus contains no information derived from that assessment. Two papers that had been "in prep" have since been published and are referenced as such in this chapter. Unfbrtunately, /brmany years past we have watched... [the American lobster] decline until some have even thought that commercial extinction... awaited the entire fishery" What is the matter with the lobster? -Herrick, 1909 Why, are there so manjy American lobsters? -Miller; 1994 INTRODUCTION Because the American lobster, Homarus amern-caraus, is the single most valuable species to the fisheries of New England, it is understandable that there is widespread concern for its health. For nearly a century this concern has centered on overfishing. However a growing number of scien-tists have questioned whether overfishing is its most serious threat, or if it is, how will we know? When harvesting exceeds the ability of an exploited species to replace itself' it is overfished. There are myriad examples of overfished stocks that have collapsed such as cod, haddock and right whales. Then there is the unusual case of the American lobster. Despite repeated warnings for nearly a century that lobster stocks are overfished and collapse is imminent, stocks throughout the western North Atlantic remained stable and in recent years surged dramatically. In fact, landings in Canada and the United States in the 1990s have exceeded record highs and most fisheries scientists agree that this increase is primarily driven by high abundance rather than simply increased fishing effort (Elner and Campbell, 1991; Pezzack, 1992; Anon. 1993a; Miller, 1994). Were determinations of overfishing wrong?.Should other factors not cur-rently in the spotlight be considered more seriously? If the primary concern is for the health of lobster stocks, how might we best monitor it? In other words, how do we best put our fingers on the pulse of this marine resource? In this chapter, 1 will describe how overfishing on lobsters is currently determined, what strengths and weaknesses exist in this approach, and whether other factors such as environmental variability, habitat, and pollution have been sufficiently considered.
13 2) ST F N F K (Ai C_ 20000. 18000 16000 14000 12000 10000 AT\\ 800 60001 40001. 2000 "The Bust" 1880 1890 1900 1910 1920 1930 1940 "The Boom" I. f+ISD Average -ISD 1950 1960 1970 1980 1990 Year Figure 8.1. Lobster landings in Maine from 1880 to 1994 with average and variance (+ I standard deviation) over the period indicated by the three horizontal lines. The period below one standard deviation below the mean is called "the bust" and above one standard deviation above is called "the boom". Data from Maine Department of Marine Resources. TEIPORAL. TRENDS IN AMIERICAN LoT;isiFi AND FIsiliNG EFFORT My review focuses heavily on Maine because it has the largest harvest of lobsters in the United States and because good records have existed for more than a century. As others have pointed out (e.g., Elner and Campbell. 1991 ) some of the most striking patterns in Maine have been paralleled in most areas throughout the western North Atlantic. One of the strongest patterns observed in the western North Atlantic is the decline in landings observed froom the turn of the century to about 1925 (Figure 8.1). This pattern was evident in all major lobster producing regions of Canada (Nova Scotia, Newfoundland, and Gulf of St. Lawrence; Elner and Campbell, 1991; Pezzack, 1992; Anon., 1995) and the United States (Harding et al., 1983; Miller, 1994). In Maine, this resulted in the all-time population low that occurred between the World Wars and ended in the mid-1940s (labeled "The Bust" in Figure 8. 1; Acheson and Steneck, 1997). Equally. striking as the bust is the "boom" peri-od which began between the 1970s and 1980s and continues in some regions today (e.g., Elner and Campbell, 1991; Miller, 1994; Acheson and Steneck, 1997). In between the bust and boom periods, landings varied in different regions but in Maine and most of the Gulf of Maine there was a significant increase in landings during the 1940s. Although for the next 40 years stocks were remark-ably stable, there. were repeated concerns that they were overfished (discussed below). One reason often cited for the general increase in landings from the 1930s into the 1990s is increased fishing pressure or effort (e.g., Fogarty, 1.995). Fishing effort on lobsters, expressed as the number of traps fished per year, shows a strong increase since World War I1 especially during the 1970s, after which (until very recently) it has largely stabilized (Figure 8.2A; see Thomas 1980 for a more complete discussion of effort). Many argue that this is only part of the story and that effective effort has continuously increased due to longer soak time, improved trapping, hauling and navigat-ing capabilities (Anon., 1996a). Traditionally landings increase with increasing effort until the maximum sustainable yield is
fN(~OL0,U(AL P'ERSII P XE E4 (l _ýN I.0 115r FER 0 -(,\\ SIS I I\\ (i 13 A 3( I-- U) 2 CD C) M11=- C: t~ 0 w < i Annual Effoi The Boom B '(a a)E C3 CD '0 C: -o Landings Relative to Effort 977) 1880 1900 1920 1940 1960 1980 500 1000 1500 2000 2500 Year Number of Traps (thousands) Figure 8.2. Lobster landings in Maine and fishing effort (i.e., number of traps fished) since 1880. A. Temporal trends in fishing effort. B. Landings relative to tishing effort. Effori is approximated by number of traps fished. Two best-lit polynomial curves yielded different results. Dow (1977) calculated a curve in 1974 showing a distinct decrease in landings with effort after landings highs recorded in 1957 and 1960. A reanalysis with data through 1994 shows a dis-tinct increase during the boom of the 1990s. Data friom Maine's Department of Marine Resources. achieved. After that point, landings will decline with continued increases in effort. It was believed thatthe fishing effort on lobsters reached in the late 1950s and early 1960s attained the maximum sustainable yield (Dow, 1977; Figure 8.2B). The dramatic increase in effort in the 1970s (Figure 8.2A) was coincident with a decline in landings (Figure 8. 1). By 1974 the trend of declining catch with increasing effort was interpreted as clear evi-dence of overfishing (see curve labeled "1974" in Figure 8.2B; Dow, 1977). In subsequent years, however, the declining trend reversed to the record levels of the recent boom. This resilience despite enormous effort has surprised managers and has contributed to a lack of confidence in fisheries sci-ence held by some in the industry. FLUCTUATIONS IN LOBSTER STOCK: OVERFISHING AND/OR TIE ENVIRONMIENTl? EVIDENCE FOR OVERFISHING: ARE STOCKS REPRODUCTIVELY LIMITED? Is BROODSTOCK DECLINING? The causes of the declinc of/thc fishe/1v are tluin-v evideni. M/ore lobsters have been taken fiom the sea than nature has been able to replace by the slow process of reproduction and growth. -Herrick, 1909 Lobster stocks have long been assutmed to be overfished. As indicated in Herrick's (1909) quota-tion above, the principal overfishing concern relates to the reproductive capacity of the stocks. Stocks that are reproductively limited have insuffi-cient fertilized eggs to maintain population densities and are thus "recruitment overfished". This is the major biological and management concern (Anon., 1996a). Economic concerns such as improving yield (e.g., "growth overfishing") are usually con-sidered a separate matter especially if the brood-stock and reproductive potential remain strong. It is possible that."growth overfishing" or harvesting lobsters before they can provide the maximum sus-tainable yield per recruit could also have ecological consequences to the stock (e.g., by shifting the size structure of the population toward smaller individ-uals) but to date, there are no indications that this affects reproduction or sustainability of the resource.
134 STENECK 18000 17000 16)000, 1500*" 1 4000 13000 1E.2000 o, f2OOO- .E 10000 10000" 9000 7000 1074 (N\\WS 1 t1, SAW)' ovr tit.Ihing I (tor (1(77) (ar'cii iced for Lovcrl hc biolo", at nianeorat~w ritii (Kro,-r 1973) 1ttatOt 1945 1950 1955 1960 196i 1970 1975 1980 1985 1990 1995 Year Figure 8.3. Overfishing and management concerns voiced by federal and Maine state fisheries managers. Since 1945 most warnin-s ofoverfishintz have been coincident with periods.of declines in landings (Figure 8.3; Miller, 1994). As Anthony and Caddy (1980) stated, "Landing declines are often inter.- preted to be stock collapse due to overfishing". However in every case, lobster stocks rebounded without a reduction in fishing effort. The fact that lobster population densities throughout their range have increased significantly in recent years indi-
- cates that they are not currently reproductively lim-ited and thus not literally recruitment overfished.
This point was amplified by Pezzack (1992) who pointed out: A low level of roodstock (recruil over-fishing) was a t-opu/ar exlilanation ftr the depressed catch rales chrillg the I970s...: however the very lacye year classes which occurred in i/e 1980s. some of which were produced by these low population levels, wseakens this argueneriu. A decline in the reproductive potential of lob-ster stocks can only result friom a decline in the abundance of broodstock lobsters. The reproductive potenitial is the broodstock sufficient to maintain the population assuming that adequate conditions for larval survival, growth and settlement prevail. To date, there is no direct indication that brood-stock is declining in abundance. For example, there is no significant trend in abundance among lobsters at or above harvestable size in the National Marine Fisheries Service's groundfish trawl surveys (Figure 8.4.; Anon., 1993a) over the 12 year period from 1980 to 1992. These surveys provide the only direct estimate of abundance used for population data on which overfishing determinations are based (discussed below). Despite the long history of suspecting stocks were overfished, there is little hard evidence to support that thesis. As pointed out by Elner and Campbell (1991), "...the events with lobsters in the A C 6-40 C. C 40 4) 4,7 Greater Than Harvestable Size Females (Incl. Broodstock) 0.61 ] B Less Than Harvestable Size Females I (All Juvenile) 0.5 7) 0.4ý 0 0 0 0.3 0.2 0.1 6 0 0 0 6 C S .40 7) C, 4,7 )92 0.5' 0.4' 0.3' 0.2' 0.1' y 2.21033 12'933.-2., W2 M 3 0 a oo 7 -u80 82 84 86 88 9( Year 80 82 84 86 88 90.92 Year Figure 8.4. Trawl survey data on lobster abundance (Anon., 1993a). A) Fully recruited lobsters (i.e., > 83 mm CL) include all potential broodstock. There is no temporal trend in the abundanceof this component of the population. B) Prerecruits (< 83 mm CL) all of which are juveniles. There is a significant increase in this component of the popula-tion. Data from NMFS Northeast Fisheries Science Center Autumn trawl survey (Anon., 1993a). Recently revised data through 1995 continue the above trend (Anon., 1996b).
northwestern Atlantic over the past 10 years sug-gest [that] recruitment can be independent of fish-ing pressures..... In a similar vein, Miller (1994) questioned the efficacy of management by pointing out that, "'The very large area over which landings increased argues against favorable management. regimes or changes in regimes as causes. Seasons, mininmm sizes. fishing effort, etc., vary a great deal over the area considered... and changes in management during the 1970's and 1980's were small." Could the demographic signal from the environment be stronger than that from fishing pressure or management measures? Given the undoubtedly great effort exerted by the fishery. the environmental control would have to be extraordinarily large. ENVIRONMENTAl.. CONTROL: A CASE FOR WATER TEMPERATlURE ON EARLY LIFE H-ISTORY PHASES Temperature has long been considered a key environmental variable for lobsters (Huntsman, 1924; McLeese and Wilder, 1958: Flowers and Saila, 1971 ; Dow, 1977; Aiken and Waddy, 1986; Fogarty, 1988; Campbell et al., 1991 ). Since some temporal trends in both lobster landings and sea surface temperatures correspond broadly through-out the western North Atlantic (Elner and Campbell. 1991), temperature is a likely candidate. However, there is no consensus on how tempera-ture affects landings. It is also important to know which phase of the lobster life history is likely to be most impacted by temperature. Many species including lobsters have a "critical period" (sensa Hjort, 1914; Frank and Leggett, 1994) or "critical phase" (senssu Langton et al., 1996) in their life history. The critical phase is the period in the life history of an organism when cohort size and ultimately population size is determined (Langton et al., 1996). If temperature controls the success of a critical phase, then it will control the abundance of the species; Three ways temperature may control landings are by regulating trapability, growth rates, and/or settlement success (Figure 8.5; Fogarty, 1988, 1995; Campbell et al., 1991; Addison and Fogarty, 1992; but see Aiken and Waddy, 1986 for other temperature effects). Because these temperature effects occur at different times in the life cycle of B"IOL'(!C,\\L I'1iRStL(TIVI£\\S ON LIMSTIR (1% '\\/RFIS[I1N(; 35 Temperature Anomaly: A Cooler Than Average Year Red seed GmWth Rate Reduced Post Larval Reduced Settlcmient Trapabilit)v \\ 0 1 2 3 4 5 6 7 Expected Time Lag (Years). 8 Figure 8.5. Expected tine lags after a sea surface temperature anomaly (e.g., a cooler than average year). the lobster, by analyzing landings relative to the years since the thermal event, it should be possible to evaluate the importance of temperature and to identify the phase in its life cycle where the impact is greatest. For example, factors affecting larval settlement may have an immediate impact on popu-lation density but will only be evident at the time of recruitment to the fishery after they reach mini-mum harvestable size (83 mm carapace length, CL) about-seven years after settlement. In contrast, changes in growth may be evident a y'ear or two after a thermal event whereas trapability will be evident the year of the temperature record (i.e., no time tag, McLeese and Wilder, 1958). The particu-lar season or month of thermal influence may also be important. For example, temperature effects on larval biology and behavior are confined to the summer months when they are in the water column. To determine the life cycle phase when the temperature effects on landings are greatest, a pro-gressive time-lagged regression analysis was per-formed (landings and Boothbay Harbor, ME sea surface temperature data from Maine's Department of Marine Resources). Regressions were run both with average and with August sea surface tempera-tures for the year of the reported catch (i.e., 0 year lag) and for each year prior to the landings for 20 years (i.e., a 20 year lag). Sea water temperatures around the time of post-larval settlement have a significant impact on stock size and future landings. The best fit between landings from 1946 to 1986 and sea surface tem-perature was determined by the proportion of vari-ance explained (i.e., the r2 value) for each time-lagged regression (Figure 8.6). The strongest sig-nificant relationship between landings and average
136 STI:-NF CK A B V.- C) 0 -0.4' 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 LAG (years) LAG (years) Figure 8.6. The proportion of variance explained by temperature with time lags ranging firom 0 to 20 years. Variance is represented as r2 based on regression analyses of mean annual temperature (A) and mean August temperatures (B). Asterisks represent significant inclusions to a multiple regression model at the 0.05 level. So that landings reflect stock size, rather than interannual variability, I used a three year running mean on landings (method of Ennis. 1986). This is necessary because at the time of harvest a warmer than average year may result in an extra molt and an early recruitment into the fishery and a cooler than average year may result in a delayed molt and a later than average recruitment into the fishery. Such noise is of little long-term consequence to the fishery. The progressive improving of the proportion of variance explained toward and away from the 6 - 8 year lag is probably in part the result of variance in cohort growth rates. No Lag 7 Year Lag 10500 10000 9500 9000 8500 8000 r2.05 -7<AA 1 ý ý I 14 15 16 17 18 August Temperature August Temperature Figure 8.7. Annual landings and mean August temperatures from 1946 - 1986 for the year of the harvest (A, no lag), and seven years after the recorded temperatures (B, 7 y lag). temperatures was found around a mode of six to seven years (Figure 8.6A). When August tempera-tures were analyzed in this way (Figure 8.6B), a similar but more pronounced spike occurred at the period between 6 and 8 years. Both analyses explain approximately the same proportion of vari-ance in landings and both show the strongest signal is around 7 years later which is consistent with the idea that thermal control of population density is at or around the time of post-larval (PL) settlement. Since settlement occurs primarily during August in Maine, thermal patterns then may be the single best environmental determinant of future landings. The wider curve resulting from average tempera-tures may reflect other more behavioral (i.e., trapa-bility in year one, Addison and Fogarty, 1992) and growth-related impacts in subsequent years, but these are minor relative to the very strong signal evident at seven years or around the time of PL set-tlement.
To better visually, interpret this analysis, Figure 8.7A shows the regression between landings and ALgList temperature in the same year (i.e.. no lag). The nonsignificant (p = 0. 12) slope is negative and I` is only 0.05. In contrast, the relationship between landings and temperatures seven years prior shows a strong positive and significant (p < 0.001) rela-tionship with an -2 of 0.535 (Figure 8.7B). (Note that the r2 values from each of these regressions is in Figure 8.6B). I focused on environmental inifluences for the 40 years between 1946 and 1986 (Figures 8.6 and 8.7) since declines during that period, were inter-preted by fisheries managers to have been the result of overfishing (Figure 8.3). Although ten-perature may have contributed to some fluctua-tions,this analysis does not indicate that stocks were not threatened over that period or that they are not threatened today by overfishing. However, patterns of decline were evidently more attributable to environmental factors than to fisheries-related impacts over that period. Fogarty (1995) showed similar results over this period using a transfer function technique. Since these fluctuations in landings have no apparent relationship with the size of the broodstock they are not evidence of overfishing. Different analyses of the recent population increase have reached different conclusions. Whereas Fogarty (1995) found the boom of the 1990s (Figure 8. I) was attributable to temperature. my analysis did not (e.g., Figure 8.6; Acheson and Steneck, 1997). Several theories have been advanced to explain this change but beyond the thermal explanation (e.g., Fogarty, 1995), most relate to changes in the biotic component of the eco-system. Prime examples are that effective nursery grounds or juvenile habitats have expanded due to recent increases in kelp and decreases in predator abundance in the coastal ecosystem (see Habitat and Ecosystem Considerations below). The point is, it is essential for those interested in detecting recruitment overfishing to be able to filter out environmental "noise" froom the fisheries signal. Clearly, many of the declines in lobster landings in Maine that were interpreted to indicate overfishing (Figure 8.3), in fact turned out to best correspond with time-lagged temperatures and the processes they affect at the time of larval settle-ment. Other environmental variables influencing \\iH I -I(A. ,ERSI TIVE' $ (E N IO S IT ER O\\E FR ISIIIN(; 137 lobster larval success have been suggested in other systems (e.g., river discharge in the Gulf of St. Lawrence; Sutcliffe, 1973. lagged 9 yrs). There are no studies I know of that indicate a shortage of broodstock, i.e., recruitment overfishing over the last half century. LOBSTER MANAGEMENT: TiE EGG PER RECRUIT DEi.I:INITIo O1 OIVERlFISHING THE EGG-PRODtJCTION-PER-RECRtJIT DEFINIION: SET AT A PRECAUTIONARY LEVEL. Federal law requires "an obtjective and measur-able definition of overfishing for each managed stock or stock complex with an analysis of how the definition was determined and how it relates to the biological potential," (Anon., 1989). A recent report of the Stock Assessment Workshop (Anon.. 1993a) concluded that the lobster fishery, as a whole (including Gulf of Maine), is overfished by the current definition of overfishing. The applica-ble definition of overfishting published in Amendment 5 to the Federal American Lobster Fisheries Management Plan (1994) is: The resounrce is recruitment overfished when, thr'oughout its range, the fishing mortality 1;ale t'F) given the regulations in place at that time under the suite of regional management measures, results in a reduction in estimated egg produc-tion per recruit to 10 percent or less of a non-fished population [110%/o]. This definition was adopted as a precautionary measure. That is, it is set at a level that should not allow reproductive or stock collapse since such an event would be a disaster to the industry for decades at least (Anon., 1996a). The conundrum is that only by experiencing stock collapse can the estimated egg production per recruit be calibrated or the efficacy of the overfishing definition be demonstrated. This definition and the egg-per-recruit (EPR) approach is the guiding light for fish-eries management in all lobster producing states and recently for Canada (Anon., 1995).
138 TEINFCK AsSUMPTIONS AND CONCERNS OFI TH EGGS PER RECRUIT OVERFISHING DEFINITION The current EPR definition is based onl the idea that fisheries models and statistics are sufficient to estimate the proportion of the lobster population that is harvested or dies each year and sets at a pre-cautionary level the proportion of tile population that must survive and reproduce to sustain the stocks. There are two primary concerns related to this definition: I) it is based on many fundamental estimates or assumptions that are either untested or untestable, and 2) it assumes that the principal threats facing the resource relate to its reproductive health as estimated by the production of eggs per recruit. There are six key assumptions necessary to determine overfishing:
- 1) The stock-recruitment relationship is known;
- 2) Stocks can be commensurably quantified throughout their range;
- 3) Mortality (both natural and fishing or F) can be estimated;
- 4) There is no large-scale geographic segregation of tile population and net loss friom a manage-ment zone due to migration is negligible;
- 5)
The necessary proportion of ovigerous lobsters relative to an unfished population to sustain the stock is known (i.e., is it 2%. 5% 10% or 20%9);
- 6)
Ecosystem change is inconsequential or does not affect the fundamental eggs per recruit relationship necessary to sustain the popula-tion. Arguably the question should be, do we know elouLIgh to manage lobster stocks this way? Is there sufficient confidence in this approach to have it be the sole basis for management? There are disturb-ing voices from fisheries scientists who suggest the answer may be "no." Below I outline some of the serious questions that have been raised over each of the six assumptions above. I) The Slock-recruitnent Relationship Is Known. Knowing or estimating the relationship between the abundance of parent stock (i.e., brood-stock) and the resulting yield of recruits to the fish-cry is central to fisheries management (Frank and Leggett, 1994). Pezzack (.1992) reiterated this assumption by stating that the "*stock recruitment relationship is the basis of much of... lobster man-agement." However he went on to point out a troubling problem-to date, "no clear stock recruit-ment relationship has been found in lobsters.". The estimated stock-recruitment relationship on which lobster stocks are mnanaged in the US and Canada was published by Fogarty and Idoine (1986; 1988). Since there are no estimates of the size of parent stock populations, these investigators used data provided by Scarrett (1964, 1973) on lar-val abundance to represent broodstock and subse-quent (time-lagged) landings for the A ,0.6" 0.5 S 0.4' S0.3 0.2' 01' Stock-Recruitment Data B 0.6 Stock-Recruitment Curve 0 lIs4 0 1953 -e0 0 0.510 1952 6 01956 r0 1949 0.4 03 0.2 0.Il 0.0 00 S 0 5 10 15 20 25 30 35 Broodstock (Stage IV (Post-larvae) Abundance) Curve forced through zero 5 10 15 20 25 30 35 Broodstock (Stage IV (Post-larvae) Abundance) Figure 8.8. The stock-recruitment relationship on which lobsters stocks in the western North Atlantic are managed (Anon., 1995; 1996ab). Broodstock (i.e., parental stock) and its resulting egg production is assumed to be repre-sented by the abundance of Stage IV post-larvae. Recruitment of lobsters to the fishery is assumed to be repre7 sented by landings. A: Data from Scarrett (1973), B: Analysis and curve-fit from Fogarty and Idoine (1986).
Northuniberland Strait in the Gulf of St. Lawrence in their analyses. The resulting plot (Figure 8.8A) shows no relationship between Stage IV post-lar-vae abundance and stock size. However, based onl the asSumLnption that no larvae willI result in no land-ings, the published curve was forced through the origin (Figure 8.8B). This curve became the stock-recruitment curve on which lobsters throughout the western North Atlantic are now managed (Anon., 1995, 1996a, b). A consequence of this stock-recruitnment curve which steeply plunges to the origin, is that there will be virtually no warning of stock-collapse. That is, over a wide range of broodstock abundance there is no change in the harvested stock until the broodstock reaches very low abundances, at which time stocks are predicted to crash. This interpreta-tion of this curve also suggests that landings alone will not be good indicators of the risk of stock col-lapse. The shape of this curve, especially its slope near the origin, is critical for the management strat-egy applied to lobsters (Anon., 1996ab). The most serious flaw in this logic is that there is no evidence that larval abundances relate to the size of broodstock..In fact, the data used for the lobster stock-recruitment curve (Figure 8.8A) shows very rapid interannual fluctuations in larval abundance. Extremely low larval abundances recorded in 1949 were followed by the highest value in 1952 which was followed by low values again in 1953 and 1954. Broodstock abundances do not and cannot fluctuate at that rate. We must conclude that larval abundance is a poor indicator of broodstock abundance and thus the curve (Figure 8.8B) is not a stock-recruitment curve. That larval abundances are variable and could result in low landings, is not the same as a brood-stock-collapse resulting from recruitment overfish-ing. Variability in local larval abundance can result from variation in reproductive success or environ-mental influences. For example, physical oceanog-raphy and meteorology affects ocean current and wind delivery patterns of competent post-larvae (Incze and Wahle, 1991). Water temperatures influ-ence post-larval growth rates (Harding, 1992) or sounding behavior (Boudreau et al., 1991, 1993). All of these factors can account for significant dif-ferences in larval settlement without any change in broodstock abundance. Further, larval settlement. 111 +'GT(>AL PERSPE-'-'TV\\, ON LOBSTER OVER)ISHINi 1 39 may not always correspond with larval abundance. For example, if postlarvae choose not to settle, or if they settle in habitats where early post-settlenient mortality is high (\\Wahle and Steneck, 1992), the resulting landings would be low or absent but not necessarilyvthe result of low post-larval abundance. Given this, it may be inappropriate to interpret the post-larval -recruitment data (Figure 8.8A) as a curve forced through zero (Figure 8.8B). The application of the stock-recruitment curve generated for Northumberland Strait was interpret-ed by Fogarty (1995) to show -a generally declin-ing trend in larval production" with the evident result being "the population declined markedly shortly after cessation of... sampling...." in 1968. This is contrary to published landings data for that region (Harding et al., 1983; Pezzack. 1992) which shows a steady decline friom 1960 to mid 19.70s. The same pattern was recorded in Maine over the same period (Figure 8.3) but clearly larvae came from different parent stocks. Had larval declines been the result of declines in broodstock, a much longer period for recovery would have been expected (Fogarty, 1995). However in both cases, without any significant management action, and continued increases in fishing effort, this decline was followed by a steady population increase for well over a decade. The stock-recruitment relationship for lobsters remains elusive because it is a problem of scale. Broodstock abundance would more likely relate to landings if the population is "closed". But it is now widely recognized that larvae come from reproduc-tive lobsters that live elsewhere and thus represent an open system or a metapopulation (Cobb and Wahle, 1994). The stock-recruitment relationship for lobsters is a window into a bigger question. In a recent review by Frank and Leggett (1994) they point out that stock-recruitment models in general have fall-en under "increasing criticism". They cite papers that argue that "fisheries scientists have shown excessive willingness to impose theory on data rather than testing the null hypothesis that there is no relationship between stock and recruitment." I submit it would be difficult to reject that null hypothesis using published data for the American lobster.
- 2) Stocks must Be Commensurably Quantified Throughout Their Range. It is difficult to quantify
140 srENECK Simall Female Lobsters (< 83 aun CL) Large Female Lobsters (> 83 mm CL) Figure 8.9. Results friom randomized stratified trawl surveys conducted between 1982 and 1991 during Autumn for the Gulf of Maine and southern New England (modified fromn NMFS Northeast Fisheries Science Center). Black blocks had one or more lobsters, unshaded blocks had none. Note that coastal regions in the central Gulf of Maine that have the highest landings have no trawled prerecruit lobsters (i.e.. < 83 mm CL) whereas sand regions of the western Gulf of Maine that have much lower landings have much higher trawled densities of prerecruits. Note that Georges Bank (east of the Great South Channel) is dominated by larger lobsters (i.e., > 83 mm CL). Offshore canyons and the Great South Channel labeled for reference. lobster abundance in regionally commensurable ways using current techniques. For example, NMFS biannual groundfish trawl surveys randomly go to different trawl locations each year (i.e., strati-fied random sampling, Figure 8.9). If in one year the trawls sample some hot spots but in other years they do not, interannual variability will be great. Trawl samples contain very few lobsters per tow. Figure 8.4A shows only about one tow in three will contain a female lobster and the resulting annual abundance estimates have high interannual vari-ability. Some of the variability relates to the sub-stratum type being trawled. Trawl-capture efficien-cy will be high in sand where lobster population densities are naturally low and very low in boulder fields where lobster population densities are high. Other variability relates to regions where trawl sampling can be conducted. To avoid damage of fixed gear (lobster traps), trawl sampling targets regions where lobstering effort is low or nonexis-tent. For example, coastal regions in central Maine where most lobsters are harvested and prerecruit densities (in #/m 2-) are greatest are not sampled (Figure 8.9). Coastal regions in sand-dominated Massachusetts where fewer lobsters are harvested and prerecruit abundances are less, are sampled. As a result, population patterns derived from trawl sampling are opposite that of landings and demo-graphic studies (Figure 8.9). Addison and Fogarty (1992) stated that: "the only reliable measure of true changes in abundance... would be direct cen-sus estimates." This ctuTently does not exist.
- 3) Mortalit, (Both Natural and Fishing Mortality, or F) Can Be Estimated. Measurements.
of natural mortality are lacking (Thomas, 1980; Conser and Idoine, 1992). An assumed 10% natural mortality per year is usually used but this may be far from the mark especially if applied to the entire
lobster population. Rates of predation are very high at the time of post-larval settlement and rapidly decreases as they grow (Wahle and Steneck, 1992; Wahle, 1992). When lobsters in coastal Maine grow to near harvestable size (greater than 60 mm CL) they are virtually immune to predators (Steneck, 1989., 1995a) because most coastal predators today are small in size (Malpass, 1992; Witman and Sebens, 1992). In contrast, on Georges Bank where large lobsters predominate (Campbell and Pezzack, 1986), annual rates of natural mortal-ity' are likely to be exceedingly low. In all likeli-hood for any given size there will be a significant habitat-related (e.g., sand vs. boulder) and region-related (e.g., coastal vs. offshore) difference in nat-ural mortality. Ontogenetic differences in mortality rates are likely to vary by orders of magnitude. The means of estimating fishing mortality for lobster is the DeLury method (Conser and Idoine. 1992; Anon., 1996a). This method assesses the rel-ative abundance of prerecruit lobsters (assumption
- f2) and based on estimated rates of growth. aSsum-ing there is no migration (assumption #4) and natu-ral mortality is 10% (assumption #3). the expected harvestable biomass oflan unfished population can be approximated. The amount observed less than that expected of an unfished population is assumed to reflect fishing mortality. Most of the assump-tions used to estimate mortality will be difficult to test. However. the assumption of no migration (assumption 44) creates a particular problem.
- 4) There is No Large-scale Geogratphic Segregation of the Population and Net Loss from a Management Zone Due to Migration is Negligible.
This assumption was reiterated by Fogarty (1995) for the population dynamics models for lobster: "a closed population is assumed in which immigration and emigration are negligible...." It is well known that the range of lobster movement increases with body size (Krouse, 1980). Large, reproductive lob-sters, may migrate hundreds of kilometers (Campbell and Stasko, 1985; Campbell, 1986, 1989) whereas young of the year lobsters may not move more than a meter (R. A. Wahle, personal communication). As a result, there are off-shore and deep water regions dominated only by large reproductive lobsters (Figure 8.9; Skud and Perkins, 1969; Campbell and Pezzack, 1986; Steneck. in prep) and shallow coastal regions dom-inated by juvenile lobsters (Steneck, 1989; Steneck RIOLI,(;(, ki-PF RSIPEC'TIVI\\E ON I-BSTEK OVI-ItRFSIIIN(G 141 and Wilson, 2001); There are serious management implications if regional losses due to migration cannot be distin-guished from mortality. For example, in the 16' Stock Assessment Workshop (Anon., 1993a), the stock assessment area of Southern Cape Cod-Long Island Sound Inshore had the highest estimated rate of mortality (exploitation rate of 81%). This zone also happens to be elongate, largely coastal with an abundance of prerecruit lobsters (< 83 mm CL, Figure 8.9). One would expect the greatest net movement of larger lobsters out of this zone to regions offshore. In contrast, the Georges Bank and South Offshore stock easement area had the lowest estimated rate of mortality (exploitation rate of 35%). This zone is dominated by large lobsters that apparently have migrated in from other regions (see Figure 8.9). Recognition of this problem with lobsters was voiced by a fisheries manager who stated: "...we all could be overestimating 'F' [Fishing mortality] values due to migration." (Anthony and Caddy, 1980). It was also identified as a general fisheries management problem by Frank and Leggett (1 994) who point out that: "pop-ulation dynamic models applied to fish populations frequently ignore dispersive processes such as immigration andemigration...." Especially since, "emigration... has commonly been viewed as the equivalent of mortality..... They go on to point out that this has been well known among ecologists (e.g.. Wynne-Edwards, 1962) who "believed that dispersal acted as a safety valve providing immedi-ate relief to the potentially negative effects of over-population." Frank and Leggett (1994) go on to conclude that "recruitment dynamics may be seri-ously misinterpreted if such dispersive processes are ignored."
- 5) The Necessary Proportion of Ovigerous Lobsters to Sustain the Stock Is Known (i.e., is it 2, 5, 10, or 20%?*). If we assume the egg per recruit management approach works, what proportion of the population must be reproductive to sustain stocks'? The target estimated egg production per recruit of 10 percent of an unfished population was proposed as a precautionary level which was acknowledged to be a rather rough educated guess based on estimates from fin fish and other exploit-ed crustaceans. Since lobster stocks were deter-mined to have suffered overall mortality rates that result in less than 10% egg production per recruit
142 S rC(fN CK for 8 of the 10 years analyzed (Anon., 1993a), yet lobster populations increased over this time, this value cannot indicate the limit of the stock's repro-ductive potential. According to NMFS scientists (Anon., 1993b): The fishinzg mortality rate which would result in a rectrtitment/ailure is not known Jbr lobster populations in the United States. It is' true that there is uncericainty about whether the 10% level is 'correct'. However, the onlv way to know fori sure is to reduce the population to the point where it collapses and to observe the level of egg pr-odtuction where the collapse occurredc. 1hor obvious rea-sons, we do not want to see this happen.... The certainty expressed in "the only way to know for sure...." may be unwarranted. If environ-mental conditions can impact lobster stocks by causing several years of failure in larval settlement, then stocks could collapse but not due to insuffi-cient broodstock or a reduced reproductive poten-tial. As shown above, stock declines or even a short-term collapse does not necessarily indicate recruitment overfishing,.sensiu striclt. Thus the question remains, how should this biological refer-ence point be determined and tested? Uncertainty regarding the 10% reference point was reflected in the Canadian decision to apply the 'egg per recruit approach but recommended a 5% biological refer-ence point (Anon., 1995).
- 6) Ecosystem Change 1.s Inconsequential or Does Not Affect the Fundamental Eggs per Recruit Relationship Necessaij to Sustain the Population.
The final assumption relates to changes in the ecosystem. The egg per recruit approach simplifies many of the complex problems described above into a few simple elements. In essence it assumes that the population dynamics of the resource depends primarily on the broodstock. While in the extreme case of reproductive collapse this is unde-niably correct, as the singular guiding principle for recruitment overfishing, it may be an oversimplifi-cation. This approach tacitly assumes that other changes in natural mortality or larval settlement success will be negligible. There are reasons to believe that these and other important components of the ecosystem have changed over tile past century. Obviouslv some abiotic chanoes such as water temperature described above may change ecosys-teni function, but there are also some relatively recent biotic changes that may be important to lob-ster stock abundance. Predator-prey.interactions are undoubtedly dif-ferent since groundfish were depleted from coastal locations. Whereas cod and other groundfish were abundant in coastal Maine during the 1920s (Rich, 1930), they have been depleted from coastal zones since the 1950s (Witman and Sebens, 1992; Steneck, 1995a, 1997; Conkling arid Ames, 1996). Thus natural mortality has probably declined over the past several decades as fewer and smaller size classes of lobsters remained vulnerable to predators. It is also possible that nursery grounds or sites for successful settlement have increased recently. Harvesting of the green sea urchin, Strongylocen-trotus droebachiensis, over the past decade deplet-ed populations of this major inacroalgal herbivore from coastal zones. As a result kelp beds have expanded throughout the Gulf of Maine (Steneck et al., 1995) and this may provide mnore sites for lob-ster settlement. Wahle and Steneck ( 1991) found that besides cobble rock some newly settled lob-sters can be found in kelp as a nursery habitat. It was also suggested that a relatively small change in predation rates early in life may significantly change the population size (R. A. Wahle. personal communication). Kelp and other macroalgae provide shelter for larger lobsters and can significantly change the local carrying capacity of some habitats, such as relatively featureless ledge or bedrock, for larger adolescent phase lobsters (> 40 mmn CL; Breen and Mann. 1976, Bologna and Steneck, 1993). In effect, this could retain harvestable lobsters in coastal zones that would otherwise migrate off-shore or to deeper water. Thus, the changes to the ecosystem are likely to detract fiom the efficacy of the egg per recruit determination of overfishing. In other words, it is entirely possible that the proportion of reproductive lobsters necessary to maintain lobster populations are likely to vary with some of these changes in the abiotic (e.g., temperature) and biotic (e.g., preda-tors, nursery grounds, habitable space) components of the ecosystem.
ARE LOBSTERS OVI*RFISII iD? Wiio KNows? Considering the imnprecision associated with stock definition, the extent to which lbactors other than spawning stock size seem to cause variability in recruitment, and the lack bf understanding of hlrval recruitment processes, deternmination ofa stock-recruitment relationship fir the American lobster is unlikely in the near future. -Ennis, 1986 Because there may be serious problems with the stock-recruitment relationship and the egg per recruit approach for lobster management does not mean stocks are not nearly overfished - they may be. The central concern should be, if they are, how will we know? Because of the nature of the current best estimate of the egg per recruit relationship for lobsters (Fogarty and ldoine, 1986. 1988), the pre-cautionary level for the allowable F is applied so that a surplus supply of eggs is always available. However fisheries scientists have openly ques-tioned whether this is the best goal for manage-ment. For example, Elner and Campbell (1991) wonder if environmental controls make "recruit-ment... independent of fishing pressure...". It fol-lows then that "traditional fisheries models based on concepts such as surplus production and stable recruitment would be largely redundant." Further, it could be argued that simplifying the biological concerns for lobsters to only a recruitment over-fishing argument distracts attention from other stock-threatening activities or events which could have impacts as great as reproductive collapse. Concerns about recruitment overfishing are really concerns about the reproductive potential necessary to sustain current lobster stocks. A critical gap in our knowledge of what sustains the stocks is not knowing the location or size of their effective broodstock. Effective broodstock are reproductive lobsters that contribute to landed lobster stocks. Gravid females that release their larvae into ocean currents that take them away from nursery grounds will not be contributing their offspring to the fish-ery and thus are not part of the stock's effective broodstock. it IIL,( .\\C AL N:-RSPI'(.1 I\\ES ON IOIWSSIL R (\\ LRFISIII I N 3 Diffe2rent regions with different oceanographic characteristics will have different effective brood-stocks. Therefore, not only will the effective broodstock for Long Island Sound be different from that of the Gulf of Maine, but also sizable populations of reproductive lobsters within the Gulf of Maine may have equally little impact to sustain their local stocks. As an additional manage-ment goal, it wouIld be very useful to locate, moni-tor and protect the effective broodstock. Because reproductive female lobsters produce large larvae after a long period of parental care, the per-egg survival rates are likely to be much greater than they are for most marine organisms. Also, since lobsters are long-lived (maximurm age may be as high as 100 years, Cooper and Uzinann, 1980) and have a long reproductive life, larval supply to nurs-ery grounds may remain high even after several years of settlement failure. All of this suggests that a more "surgical approach" to fisheries manage-ment is possible for this species than is or has tra-ditionallv been used (Steneck. 1996). If effective broodstock persists in deepwater refugia, then steps should be taken to protect that component of the population. For example, it Would be prudent and more risk-averse to prohibit the harvest of over-sized and v-notch lobsters in other state and federal waters. Recent interest in metapopulation models for managing the American lobster (Anon., 1996a) tacitly recognizes the significance of self-segregat-ing broodstock persisting in a ref'uge fr'om highly vulnerable juvenile stocks. Until there is consensus on the best approach for conserving broodstock, multiple independent approaches should be less risky. CONCERNS OTHER THAN OVERFISHING If lobster stocks crashed due to factors other than broodstock abundance or egg production, the economic impact would be just as severe. For this reason, other key factors should be considered in assessing the health of lobster stocks. Two impor-tant issues that relate more to the lobster's environ-ment than to its reproductive health, are habitat degradation and pollution. HABITAT: A DEMOGRAPHIC BOTTtLENECK IN TIlE EARIY BENTHIC PHASE?
144 sf*'K*r-If lobster population densities are regulated by settlement success as has been shown for reef fish (Doherty and Fowler, 1994), barnacles (Connell, 1985; Gaines and Roughgarden, 1985) and for ben-thic assemblages in general (Underwood and Fairweather, 1989), then factors contributing to successful settlement may well play a larger role in their demographic success than will broodstock size per se. In any location, successful settlement requires (I) available competent larvae (which requires sufficient laral production and oceano-graphic dispersal; see Underwood and Fairweather, 1989), (2) the propensity to settle (e.g., sounding behavior, Boudreau et al., 1991 ; and appropriate tactile, visual or chemical cues, Schelterna, 1974) and (3) available nursery grounds (Wahle and Steneck, 1991). Successful settlement requires each of the con-ditions be met. For example, a demonstration of oceanographic control on lobster larval availability is evident in the larval shadow created by the lee side of islands where settlement is significantly reduced (Incze and Wahle, 1991). The propensity of lobster post-larvae to settle may be controlled by water temperature (Boudreau et al., 1991 and dis-cussed above). Assuming those first two conditions are met, available nursery grounds may control recruitment of lobsters to the benthos (Steneck, 1989; Cobb and Wahle, 1994) and thereby control the ecosystem's carrying capacity. Newly settled lobsters have very specific habi-tat requirements for small shelter-providing habi-tats such as peat reefs or cobble beds (Able et al., 1988; Cobb and Wahle, 1994). Experiments have shown that settling lobsters suffer extraordinarily high rates of predation outside of refugia (Wahle and Steneck, 1992). The median time to the first attack from small, commercially-unimportant predatory finfish is 15 minutes (Wahle and Steneck, 1992; Boudreau et al., 1993). These fish predators (primarily juvenile cunner, sculpins and shannys) are ubiquitous in shallow coastal zones where average densities of nearly one per meter square have been recorded (Malpass, 1992). Coastal settlement of lobsters is primarily within the upper 20 meters (Figure 8.10). Since lobster settlement is largely confined to shallow (Figure 8.10) cobble nursery grounds (Wahle and Steneck, 1991), this habitat is an 4 14 C C) CA 2 I 5 ir 1011 20 n Collector Depths Figure 8. 10. Lobster settlement as a function of depth in coastal Maine. Data firomn artificial lobster post-larval collectors placed 1 July and retrieved 15 September 1995. Number of n12 collectors is represented above each bar. Error bar indicates one standard deviation. Habitat Distance from Shore E Watershed Intertidal Subtidal Nearshore Oflfhore Pelagic X -2 [-Lara ac X I Z Benthic U 7F,. Clay S Mud Sand -Adults ¢.) Sand f'Att Gravel Cobble X3 Boulder Figure 8.11. A habitat-life history matrix for the American lobster (Langton et al., 1996). Ontogenetic phases (XI, youngest to X5, adult) relative to the dis-tance firom shore, or water depth and substrate complex-ity. The point X3 represents early benthic stages which are critical phases in the life history of this species (most habitat-restricted). Shallow cobble bottoms are an essential habitat because only there are settling lobsters safe from predators. "essential habitat" (sensu Langton et al., 1996) or a demographic bottleneck for this species (represent-ed as the constriction in Figure 8. 11). Furthermore, because early benthic phase lobsters are concentrated in cobble bottoms for the first several years of their life and this habitat comprises no more than 2 to 10% of coastal substrates (Kelley, 1987). this habi-tat is particularly at risk and should be a high prior-ity for protection (Steneck, 1995b).
FISHING IMR'ACTS ON HABITAT lobster nursery grounds and preferred habitats are vulnerable to some fishinng and other human activities. The primary risks are friom sedimenta-tion (i.e., dredged materials) and dragging, both of which reduce spatial complexity (Auster et al., 1996) and from pollution (Harding, 1992). For example, the increased effort in sea urchin harvest-ing has recently accelerated dragging activity in some coastal zones and adds to the growing list of other species harvested that way such as scallops and mussels. Recent studies by Canada's Department of Fisheries and Oceans assessing the impacts of dragging for sea urchins in Passamaquoddy Bay. reported the following (Robinson et al., 1995): Visual!y. the e/jkcts o/lhe /rags on the habitat were the disruption ofthe bottom substrate as maony1 boulders have been turned over and dislodged from the secli-Inere.... There was... some loss of mnacroalgae due to the dragging. Dragging also had an imnpact on the lob-ster pPotulations at the MVinister's lslcind site as the density of lobsters in the experimental /)lot decreased to zero over the course of the dragging while the con-trol plot remained constant. Although Robinson et al. (1995) only looked for large, relatively mobile, lobsters (which they conclude may have evacuated the area), the smaller early benthic stage lobsters, if present, would be unable to exit the drag area because of the added risk of encountering predators (Wahle, 1992), such as scUlpins, which often increase in abundance as a result of dragging. POLLUTION CONCERNS: DEMOGRAPHIC IMPACT?"9 Pollution is often a source of concern for all marine organisms. This is particularly true for organisms such as juvenile lobsters that live in shallow and heavily populated (including industri-al) regions. In major reviews of the responses of [IU)I.)(.(CAL PILRSE('IVS '1 N LESON IER Q\\ERHF[IS ING 145 lobsters to contaminant exposures (Hlarding, 1992: Mercaldo-Allen and Kuropat, 1994) numerous accounts were given of detectable levels of various pollutants and, when known, lethal limits. It is beyond the scope of this paper to review this sub-ject in detail. However very little data exist on how most pollutants impact natural lobster populations. Most described pollution effects are relatively local. While lobsters readily accumulate detectable levels numerous heavy metals, polycyclic aromatic hydrocarbons, pesticides and other anthropogenic compounds,-there is little evidence that these impact the population dynamics of lobsters. Often concentrations in nature are well below those iden-tified as having a lethal impact, however, oil spills* are a notable exception. As with other contaminants, spills of oil and other petroleum products can be highly variable in their impact. Crude oil contains hydrocarbons and metals. Mortality impact is greater for larval and juvenile stages than it is for adults in general. Exposure to no. 2 fuel oil at <0.15 mg/L for 5 d can make lobsters unresponsive to food. Higher exposure (1.5 mg/L) causes-gross neuromuscular responses with a loss of coordination and equilibri-urm. Demographic impacts are variable because weather (wind, sea), temperature and the nature of the petroleum product control exposure and physio-logical effects. For example, in 1970, Bunker C fuel oil was spilled in Chedabuco Bay, Nova Scotia and in 1979 a similar incident occurred in Cabot Strait, but in neither case was there a measurable impact on mortality or harvest. In contrast, about 825,000 gallons of No. 2 fuel oil leaked into coastal waters of Rhode Island in January 1996. This was coincident with turbulent weather and resulted in significant lobster mortality. "Preliminary estimates suggest that...a million lob-sters were stranded" (Cobb and Clancy, 1996). Adjacent coves exposed to the same storm swell but no fuel oil had no washed up lobsters (Stan Cobb, personal communication). Studies are con-tinuing but it is felt that highly turbulent conditions and cold weather (poor evaporation) conspired to mix sufficient fuel oil downward into the water column to have had a toxic impact on the local population. While this has been locally devastating, it is unknown how widespread the affects will be.
146 S I N H:( 'K CONCiIUSIONS AND SOMi)E MANAGENIENT IN IPIICATIONS Despite nuimerous predictions that lobster stocks were recruitment overfished and on the verge of reproductive collapse, landings have remained remarkably constant and in the past decade significantly increased. Although repeated and recent reviews by fisheries scientists affirmed past determinations of overfishing, there are rea-sons voiced by other fisheries scientists to question some of those conclusions. Fundamental compo-nents of fisheries models employed for lobsters have been insufficiently tested and perhaps are untestable. There are published and logical argu-ments against accepting stock-recruitment curves, estimates of total mortality and assumptions of ecosystem stability. Until the abundance of the effective broodstock for harvested stocks of lob-sters is known, the stock-recruitment relationship cannot be estimated. Furthermore, fisheries scien-tists have been unable to sort environmental noise from fisheries-induced signals. As a result, the pri-mary reliance on specific estimates Of egg produc-tion per recruit relative to estimated unfished popu-lations requires a level of resolution that to date may be unattainable. If this is the case, then we. must conclude that we simply do not know if lob-ster stocks are recruitment overfished. Thus.the concern about risk of "commercial extinction" voiced nearly 90 years ago by Herrick (1909) remains, but scientific evidence in support of that concern is still lacking. I raise these concerns with the hope that a more prudent course of action will be initiated which includes additional new multiple indepen-dent estimates of the health of lobster stocks. Specifically, the distribution, abundance and loca-tion of.the effective broodstock should be deter-mined, monitored and if possible protected. The same should be done for lobster nursery grounds. To that end, regional and temporal patterns in lob-ster settlement should be determined and moni-tored. This diverse approach for determining over-fishing on lobsters uses appropriate spatial scales, considers differences in lobster ontogeny, associat-ed changes in habitat requirements (e.g., segregat-ed life history phases), and it should filter out envi-ronmental noise so that real threats to the reproduc-tive capacity of the stocks can be identified and acted oil more effectively. Understanding environ-mentally-induced changes in stock size is impor-tant so that industry and managers alike do not mistake short-term declines for fisheries-induced reproductive collapse (recruitment overfishing). Such knowledge would also improve scientists' ability, to predict natural changes in stock size which. if demonstrably correct, should improve the credibility of the scientific process in the eyes of industry. The ultimate goal for lobster managers is not just to answer the question, "are we overfishing the American Lobster?", but to convince industry to take action when it is clear that they need to do so. In the meantime, a risk-averse strategy of pro-tecting effective broodstock and nursery grounds would be a logical course of action. It requires pro-tecting essential habitats for critical life-history phases (sensu Langton et al., 1996) but if the appropriate spatial scales are selected, this action could be done surgically (Steneck, 1996). ACKNONXLEDG XIENTS Ideas and perspectives presented here resulted from years of mostly productive discussions and debates with numerous colleagues. Jim Acheson, Bill Adler, Robin Alden, Ted Ames, Peter Auster, Herman (Junior) Backman, Bob Bayer, Stan Cobb, Dick Cooper, Dave Cousens, Dave Dow, Bruce Estrella, Mike Fogarty, Arnie Gamage (and the South Bristol Fishermen's Coop), Joe Idoine, Lew Incze, Jay Krouse, Peter Lawton, Doug McNaught, Jack Merrill, Alvaro Palma, Judith Pederson, Doug Pezzack, Peter Sale, Rick Wahle, Bob Wall, Pat White, Carl Wilson and Jim Wilson. Drafts were read by Peter Auster, Robert Buchsbaum, Mike Fogarty, Bill Robinson, Rick Wahle, Jim Wilson and Steff Zimsen. Some strongly disagree with some of my conclusions, others agree, and to all I am grateful. Whereas some good ideas no doubt came from some of those listed above, all errors are entirely attributable to me. I am indebted to NOAA's National Undersea Research Program's National Research Center at the Univ. of Connecticut at Avery Point (Grant No. NA46RUO 146 and UCAZP 94-121) and the University of Maine Sea Grant College Program for funding research cited herein.
LITERATIIRE CITED Able, K., K. I,. Ileek, M. P. Fahay and C. T. Roman. 1988. Use of salt-marsh peat reefs by snall juvenile C lobsters on Cape Cod. Massachusetts. Estuaries
- 83-86.
Aeheson, J. M. and R. S. Steneck. 1997 Examininig the bust then boomn in the Maine lobster industry: The perspectives of fisherment and biologists N Am.. Fish. Mvnas. 17: 826-847. Addison,.J. and M. Fogarty. 1992. Juvenile lobster habitat limitation: what can landings tell us" The Lobster Newsletter 5: 10-12. Aiken, 1). E. and S. L. Waddy 19)86. IEnvironmental intluence on recrtiuitinent ot the. American lobster, lomoatus taericatonsh: A perspective. Can. J Fish AQUat. Sci 43, 2258-2270. Anon. 1989. Congressional Federal Register. Part 6i02 Guidelines. Anon. 1993a. National Marine Fisheries Service Report of the l6th Northeast Regional Stock Assessment WVorkshop (16th SAW). Stock Assessment Review Committee (SARC) donsensus sum-matr of assesstments. Northeast Fisheries Science Center Reference Document 93-i8. Anon. 1993b. Lobster Overfishing Deflinitions and Stock Assessment. Maine Lobstermens Association Newsletter. submitted by "Staff of New England Fisheries Science Center". Anon. 1995. A Conservation Framework fbr Atlantic ILobster: Report to the Minister of Fisheries and Oceans. Fisheries Resource Conservation Council. FRCC95.R. Minister of Supply and Services Canada. Anon. 1996a. A Review. of the Population Dvinttnics of Amnerican Lobsters in t(ie Northeast. Report for the Northeast Stock Assessment Review Commrittee. National Marine Fisheries Service and T'he Atlantic States MI arise Fisheries Coin mission. Anon. 1996b. National Marine Fisheries Service Reporit ofthIe 6th Northeast Regional Stock Assessment Workshop (17th SAW). Stock Assessment Review Committee (SARC) consensus suti-mary of assessnents. Noetheast Fisheries Science Center Re*erence Document 96. Anthonv, V. C. and.1. F. Caddy (eds.). 1980. Proceedings oflthe Canada - U. S. Workshon on Status of Assessment Science for N. W. Atlantic lobster (Homaris aoinricasmti Stocks. St. Andrews, N., 1_ Oct. 24-28. 1078). Can. Techb Rept. of Fish. and Aquat. Sci. No. 9312. Auster, P. J.. R. J. Malatesta, R W L angton, L. Watling, P. C. Valentine. C. I. S. E. Donaldson, *'A. I.anton and 1. G Rabb. 1996. The impacts of mobile fishing gear on seafloor habitats in the Gull' of Maine (Northwest Atlantic): implications for conser-vation of fish populations. Rev. Fish. Set. 4 1-44. Bologna, P. and R. Steneek. 1993. Kelp beds as habitat for the American lobster, I-Iomarus americanus. Mar Eeol Pron. Ser. 100: 127-134. Boudreau, B.E., E.E. Bourget and Y. Simard. 1991 Behavioral responses of the planktonic stages of the American lobster Hoomarus americanus to thermal gr-idients and ecological imopli-cations. Mar. Ecol. Pros. Ser. 76: 12-23. Boudreau, B., E. E. Bourget and Y. Simard. 1993. Effect of age, injury, and predator odors on settlement and shelter selection by lobster Homairus amnericanus postlarvae. Mar. Ecol. Progr. Ser. 93: 119-129. Breen, P. A. and K. I. Mann, 1976. Changing lobster abundance and the destruction of kelp beds by sea urchins. Mar. Biol. 34: 137-142. Campbell, A. 1986. Migratory movements of ovigerous lobsters, Homarits americanus, tagged offCGrand Manan, Eastern Canada. Can. J. Fish. Aquat. Sci. 43: 2 197-2205. Campbell, A. 1989. Dispersal of American lobsters, Homaous ameri-canus, tagged off southern Nova Scotia. Can. J. Fish. Aquat. Sci. 46: 1842-1844. Campbell, A. and D. S. Pezzack. 1986. Relative egg production and abundance of berried lobsters, Homarus americanus, in the Bay of Fundy and offsouthwestern Nova Scotia. Can. J. Fish. Aquat. B11L&(0kCA\\I H'm, sI\\'E, ON o _x05-.Lri OHtRtlERFISII\\(.; 147 Sci. 43: 2190-'2196. Campbell, A. and A. B. Stasko. 1985. Movement of tagged American lobsters, lMomortis omtcicoCits, off Southwestern Nova Scotia. Call J. Fish. AQutat. Sci. 42: 229-238. Campbell. A.. D..1. Noakes and R. W. Elner. 1991. Temuperatule and lobster, H-omartus americants, yield relationships. Can. J. Fish. AoUat Sd. 48: 2073-2082. Cobb, J. S. and M. Clancy. 1996. Oil spill in Rhode Island. The ILobster Newsletter. 9: 1-2. Cobb, J. S. and R. A. Wahle. 1994 Iarly life histoty and recruitment processes of clawed lobsters. Crustaceana. 67: 1-25. Conkling P W. and 'r. Atties. 1906 Penobscot fisheries in the 20th Century. Ii Penobscot: the Forest Rivet and Bay. D. D. Platt (ed ) Island Institute, Rockland, Me. Pp. 46-65 Conmell,,I. H1 1985, The consequences of variation in initial settle-ment vs. post-settlement mortality in rocks' intertidal comminitin-ties. J. Exp. Mar. Biol. Ecol. 93: 11-45. Censer, R. J. and J. Idoine. 1992. A Modified DeLurv Model for Estimating Mortality Rates and Stock Sizes of American Lobster Populations. Papers of the Northeast Regional Stock Assessment Wkorkshops. Appendix to CRD 07, Research l)ocumctii SAW 14/7. Cooper, R. A. and.1. R. Uzmann. 1980. Ecology of juvenile and adult I loitartis T'he 13iolo2v and Mananement of Lobsters. Academic Press Inc. 2: 97-142. Dohhc;, r and T. Fowler. 1994. An empirical test of recruitment hit-itation in a coral reef fish. Science. 263: 935-939. Dos. D. 1977 Relationship of'sea surfIce temperature to American and 1 LIropeani lobster landings. J. Cons. PermIt. lilt. Explor. Mer. ,7: 'S6-101. Fitner, R W. and A. Caitpbell. 1991. Spatial and temnporal patterns it recruitment lbr Anici can lobster, lomirus aimericanus in the northwestern Atlantic. Menioirs. Queensland MLuseumIt 31: 349-363. Ennis, G. R 1986. Stock.definition, recruitment variability and larval recruitment processes in the American lobster. Homtamus ameri-canus: A review. Can. J. Fish. Aquat. Sci. 43: 2072 -2084. Federal American Liobster I isheries tManagemtient Plan. 1994. A.itiended. Flowers,.. M. tnd S. B. Saila. 1971. An analysis of temperature elfcots on the inshore lobster fishery.I. Fish. Res. Bd. Cait. 29: 122 1-1225. Fogarty, M. J. 1988. Time series models for the Maine lobster fish-er-: The effect of temperature. Can. J. Fish. Aquat. Sci. 45: 1145-1153. Fogarty' M. J. 1995. Populations. fisheries and management. In: Biolopv of the lobster 1t6maorns americanus. J.R. Factor (ed.). Academic Press, NY. Pp II 1-137. Fogarty, NM..1. and.. S. ]dome. 1986. Recruitment dynamics in an American lobster (Horaruts americanus) populaition. Can. J. Fish. Aquat. Sci. 43: 2368-2376. Fogarty, N.l J. and J. S. [dome. 1988. Application ofa yield and.egg-production model based oit size to an offshore American lobster population. Trans. Aim. Fish Soc. 17: 350-362. Frank, K. T. and W. C. Leggett. 1994. Fisheries ecology in the con-text of ecological and evolutionary theory. Ann. Rev. Ecol. Syst. 25: 401-422. Gaites, S. and J. Roughgarden. 1985. Larval settlement rate: A lead-ing determinant of structure ii asi ecological community of the marine intertidal zone. Proc. Nat]. Acad. Sci. USA. 82: 3707-3711. Harding, G. C. 1992. American lobster (Homarzs americanus Milne Edwards): A discussion paper on their environmental require-ments and the known anthropogenic effects on their populations. Can. Tech. Rep., Fish. Aquat. Sci. 1887: 1-16. Harding, G. C., K. F. Drinkwater and W. P. Vass. 1983. Factors influ-encing the size of American lobster (/omaruts americanus)
148 Sri(N;N stocks along the Atlantic coast ol Nova Scotia, (Ulfof St. Lawrence, and Gulf of Maine: A new synthesis. Can JY Fish. A(uat. Sci. 40: 168-184. Herrick, F, 11, 1909 Natural history ot'the Amerieican lobster luIll Bureau Fish 29 15 3-408 HIjort... 1914. Fluctuations in the great fisheries of northern Europe viewed in the light of biological research. Rapp. P-v. Rdun. Cons. Int. Lxplor. Mer 20: 1-228. Huntsman. A. G 1924. Limited factors for marine animals 2. Resistance of larval lobsters to extremes of temperature. Can. Bil. Fisheries. 2: 91-93. Ineze. L. S. and R. A. Wahlc. 1991. Recruitment frotm pelagic to early benisibc phase in lobsters Homatrus americaons. Mar. Ecol. -Pro",. Ser. 79: 77-87. Kel ley J. 1987. Sedimentary Environments along Maine's Estuarine Coastline. In: A Treatise otn Glaciated Coasts. D.M. FitzGerald and P. J. S. Rosen (eds.). Academic Press. New York. Pp. 151-176. Krousc, J. S. 1973. Maturity, sex ratio, and size composition of tlte tnatural population of American lobster. 1onti't.s a"nei iccIalils. alone the Mainre Coast Fish. Bull 71: 165-173. Krouse, J. S. 1980. Summary of lobster. Hotnarus antericanus, tag-grig studies in American waters ( 1898-1978). Ca'. Tech, Rep Fish. AqLat. Sci. 932: 135-151. Langton, R., R. Steneck, V. Gotceitas, F. JuLanes and P. Lawton. 1996. The interface between fisheries research and habitat man-aeclilent. N. Am J. Fish. Manaat. 1-7. 'Malpass, W. 1992. The Role of'Snall Predatory Fmifish in the Structure of Coastal Benthic ComnMatities in Maine. M.S. "lhlesis. I.)epartmnent ol Oceanog rapllh, nisiv. of I daine. MeLeese, 1). W. and D. G Wilder, 1958. The activity and catchabilitv of the lobster (Homatnrus antercants) in relation to tamperature. J. Fish. Res. Bd. Can 15-134 5 -135 4. Mercaldo-Allen, R. and C. A. Kuropat. 1994. Review o1'American Lobster (Homartis americanus) HI abitat ReClui remenits and Responses to Contaminant Exposure. NOAA Technical Memorandum NMFS-N'-105.) Miller. R. 1. 1994. Why are there so many American lobsters? The Lobster Newsletter 7:.14-15. Pezzack, D. S. 1992. A review of lobster (Hoaictrus americanlts) landing trends in thle Northwest Atlantic 1947-1986. J. North. Allt. Fish. Sci. 14: 115 - 127. Rich, W. I-I. 1930. Fishing grounds of the Gullf of Maine. Report of the United States Commissioner of Fisheries 1929: 51-117. Robinson, S., A. Macintyre and S. Bemier. 1995. The impact of scal-lop drags on sea urchin grounds. In: 1994 Workshop on tite Manaoenment and Biologv of the Green Sea Urchin (Sironzilocentrotms droebachiensis). Boothbay Harbor ME. Pp 102-121. Scarrett, D. J. 1964. Abundance and distribution of lobster larvae (Homnarus americanus) in Northumberland Strait. J. Fish. Res. Board Can. 21: 661-680. Scarrett, D. J. 1973. Abundance, survival, and vertical and diurnal distribution of lobster larvae in Northumberland Strait, 1962-1963, and their relationship with commercial stocks. J Fish. Res. Board Can. 30: 1819-1824. Scheltema, R.S. 1974. Biological interactions determining larval set-tlement of marine invertebrates. "TJalassia Jugosl. 10: 263-296. Skud, B. E. and 1I. C. Perkins. 1969. Size Composition. Sex Ratio. and Size at Maturity of Offshore Northern Lobsters. U. S. Fish and Wildlife Service Special Scientific Report. 598: 1-10. Steneck, R. S. 1989. The ecological ontogeny of lobsters: In situ stud-ies with demographic implications. In: Proc. Lobster Life History Workshop. 1. Kornfield (ed.). Orono, Me. 1: 30-33. Steneck, R. S. 1995a. The GuIf of Maine: A case Study of over-exploitation. In: Fundamentals of Conservation Biology. M.L. Hunter, Jr. Blackwell Science. Pp 209-212. Stetneck, R. S. 1995h. A framework for protecting regionally signifi-cant sabhitats: Fll iotonttental science considerationss. I: Improving tile Interaction between Envsirontlental M'lanagemient and Coastal Occan Sciences. Proccedings National Research Council SylposiunLm, National Acadetty Press, Wtashington, D.C. Steneck. R. S. 1996. Is habitat necessarv for sutstainabilitv? How can wea find out? II: New Entland isheries: aniitni fr tfile IFLuture. ML. Mooney-Seus. I1. C. Tausig and G. S. Stone (eds.). New England Aquarium Aquatic Flortum Series (Report 96-2). Pp 54-63. Steneck. R. S. 1997. Fisheries-induced biological changes to the structure and ittcnction tf the Gtulf of Mainc ecosystetl. Proceedin"s of Reional Association of Marine Researchers of tihe Gulfo tfMaile SVm'nposuiUm. St Andrews, NB. September 1996. Steneck. R. S., D. McNaught and S. Zimsen. 1995. Spatial and tem-poral patterns in sea urchin populations, herbivorY and algal commtuttity structure in the Gulf of Maine. In: 1994 Workshop ott tile Mana'l aenet and Biolosv of tie Green Sea UIrchin (.S1ot,,liiocelt/rotus dtosi'octibctt sis t. floothbay Harbor Me. Pp 34-73. Stenseck, R. S. and C. J. Wilson. 2001. Long-termi and large scale spa-tial and temporal patterns in demographs and latdings of tlse American lobster, Homarus aniericaonts in Maine..1. Mar. Freshwater Ras. 52: 1302-1319. Suttclitre, W. 1. Jr. 1973. Correlations between seasonal river dis-charge and local landings of Aierican Iobster (Homiarns ateri-catts) and Atlantic halibut (Hp)pogtossus hipjpoglosstsl it tlte GulfLf St. I..Lawrcil.e.. Fish Res Bolarc Caii. 30: 856-85Q. Thomas, J. 1980. Measure ofeflort. In Proceedinas of thle Canada - U.S. Workshop ofAssessment Sciencea for N. W. Atlantic lobster (I!ontarus americanits) Stocks. V.C Anthony and J. F. Caddy (eds.). St. Andrews, NB.. Oct. 24-26, 1978. Can. Tech. Rept. of Fisheries and Aquat. Sci. 932. 1Pp 85-92. Thotnas, J. 1983. L.obstermen, b ilogists dispute future o 'catch. In: Kennebec Journal October 8, 1983. W. Cockerhatt Pg. 17. Underwood, A J. and P. G. Fairweather. 1989. Supply-side ecology and benthic marinc assemblagesI Trends Ecol. svoll 4: 16-19. Wahle. R. A. 1992. Body-size dependent antipredator mechanisms of thle American lobster. Oikos. 63: I-9. W\\ahlc, R. A. and R. S. Steneck. 19 1. Recruittiment ihbitats and sintrs-er grounds of the American lobster lHomanitis amieiicatits Millie Edwards): A'dettiographic bottleneck? Mar. Ecol. Pro,. Ser. 69: 131-243. Waltlc, R. A. and R. S. Stetteck. 1992 Habitat restrictions in early benthic life: Experiments on habitat selection and in situ preda-tion with the American lobster. J Exp. Miar. Biol. Eeol. 157: 91-114. Witman. J. 1). and K: P. Sebens. 1992. Regional variation in fish pre-dation intensity: Ati historical perspective its the Gulf otf 'Maine. lecolotia 90: 305-315. Wynne-Edwards V C. 1962. Animal Dispersion in Relation to Social Behaviour. Edinburgh: Oliver & Boyd.
- UNIMA-K%
(\\ ýN(L{.OUNS 149 Chapter IX The Role of Overfishing, Pollution, and Habitat Degradation on Marine Fish and Shellfish Populations of New England: Summary and Conclusions ROBERT BUCRSBAUM Wassachusents Audubon Society 346 Grapevine Road [,PFenham,. MA 01984 USA Suddenly the idea flashed through mv head that there was a unity in this complicationt--that the relation of one resource to another" was not the end of the story. Hfere were no longer a lot of difte'rent, independent, and often antago-nistic questions, each on its own separate little island, as we had been in the habit f/thinking. hI place of them, here was one single question wiith many parts. Seen in this new light, all these separate questions fitted into and made up the one great central problem of the use of the earth for the good of man. -Gijford Pinchot, 1947 The purpose of this chapter is to synthesize the information provided in the earlier chapters on the impacts of overfishing, pollution, and habitat degradation on certain groups of fish and shellfish. populations in the Northeast and to consider what the implication are for the future of the marine ecosystem. These three anthropogenic impacts have affected groundfish, anadromous fish, inshore bivalves and lobster differently. The chapter by Murawski makes a convincing case for overfishing as the major factor responsible for the recent. decline in New England groundfish species. The relative importance of each of the three factors is less obvious with the other groups of marine organisms. Habitat degradation, particularly dams that block access to spawning areas, have had a major impact on populations of anadromous fish, but pollution and overfishing have also influenced a number of these species. The chapters by Brousseau and Steneck suggest that populations of lobster and nearshore bivalves are largely deter-mined by natui-al variability in yearly recruitment of juveniles, at least in the areas they studied. This variability may mask any anthropogenic influences on these two groups, although the absence of reliable population data, particularly with nearshore bivalves, makes predictions difficult. DENIERSAL SPF.CIES (GRouNDIwSu1) THE ROLE OF OVERFISHING AS A CONTROl. ON GROUNDFISH It would be hard to dispute the notion that overfishing has been the major factor leading to the current decline in groundfish in the Northeast. As Murawski describes in Chapter 2, populations of groundfish most important to the commercial fish-ing industry are presently at low population num-bers compared to historic levels. The cause of these population declines has been extremely high rates
I () [,].{- fjsi l-" of fishing mortality on most groundfish stocks throughout the 1980s and up to the mid-1990s. During this period, not only did gear. become more efficient at catching fish but also there was a rapid increase in the number of people entering the fishery, spurred by government programs. About one-third of groundfish. species managed by the New England Fisheries Management Council are currently classified as overfished based on rate of harvest and long term overfishing defini-tions (NMFS, 2001). Groundfish stocks. have been characterized by both growth and recruitment over-fishing (i.e. declines in yield attributable to har-vesting smaller and smaller fish and declines in recruitment ofjuveniles due to low spawning stocks). Catch per unit effort, another indicator of the status of fish stocks in relation to fishing effort, steadily' has declined for. groundfish despite the improvements in fishing technolooy. The influence of fishing on New England com-rnercial fish is not just evident from the past two decades. Murawski points out that fish populations, such as cod, haddock, and Atlantic herring, have historically reflected the intensity of fishing effort. This has been particularly pronounced since the increased industrialization of fisheries in the early, part of the 20th Century. There have been some recent improvements in 'some fish stocks, such as Georges Bank yellowtail and haddock, in response to restrictions on fishing effort and area closures, implemented with increas-ing severity since the early 1990s. With reduced fishing mortality, older, larger fish are surviving longer, leading to anticipated improved spawning success and less dependence.of the fishery on new recruits. Overall biomass numbers, however, are still too low for groundfish to support increases in fishing effort at this time. Exploitation rates of Gulf of Maine cod and whiting are still above rebuilding target. One piece of evidence that relates the decline in groundfish to overfishing is the observation that the recent decline in groundfish has been limited to those commercial species that have been heavily exploited by commercial fishers. Species that are not being targeted or that are subject to strict man-agement measures have not been depleted or have recovered. As an example, fishing effort on two pelagic species, Atlantic herring and mackerel, has been low since foreign vessels left New England waters after the passage of the Magnuson Fisheries Conservation and Management Act of 1976. The biomass of these two species has increased markedly in the past 30 years, and they) are both listed as underexploited and at high abundance by NMFS (1998). Striped bass, whose allowable catch by both commercial and recreational fishers was drastically reduced in the 1980s as a management response to low populations, are now considered recovered and are touted as a fisheries management success story. The recovery of these species has been a direct responseto lower exploitation rates. I IAVE TI IERE 1EEN POPULA'rION Er- :IF(CS ON GROUNDFISII FROM Toxic POIJAMTANTS? The population effects of toxic pol.lution are less clear than overfishing. With the exception of oil spills, pollution rarely causes direct mortality, but rather makes fish more vulnerable to other sources of mortality. The Gulf of Maine contains a number of the most contaminated sites in United States coastal watersfor polycyclic aromatic hydrocarbons (PAHs), chlorinated hydrocarbons (e.g. chlorinated pesticides and PCBs), and several trace metals. The effects of pollutants at the cellular, physiological, and whole organism level in fish from some of these contaminated harbors can be quite striking.. Thurberg and Gould (Chapter 4) cite numerous examples of physiological alterations on gadids and flounders caused by heavy metals and organic contaminants. For fish exposed to pollutants, the survivorship of eggs and juveniles is lower than that of adults, although physiological impacts are observed at all life stages. There is very little infor-mation on the population effects of these pollutants even where effects on reproductive physiology' have been noted. As difficult as it is to relate toxic pollution to populations of fish in the most contaminated sites in the Northeast, it is even more challenging to understand what the subtle effects, if any, are of long term exposure to low levels of contaminants. This latter situation is more relevant to the overall region since the concentrations of contaminants in all but a few urban harbors within Massachusetts Bays and the Gulf of Maine are below the level
SIJNIMMKY AND ( ONCLA;MONS 15 1' where acute effects are possible. Even pelagic species that may travel far offshore, such as tuna and swordfish, are exposed to some level of land-based pollutants, as evident fiom the recent Environmental Protection Agency/Food and Drug Administration fish advisory oil nmercury3 contami-nation in seafood (http://wwwv.epa.gov/hercurv/advisories htm ) (USEPA, 2004). Studies of impacts of toxicants in New England have been carried out on winter flounder, an inhabitant of some Pollhted harbors. The goal of much of this research has been to examine site-specific effects on the fish or to explore public health risks. Other than direct toxicity from oil spills, the effects of even high levels of contaminants on the populations of flounder and other marine organisms have proven very difficult to isolate from other variables that influence reproductive behavior and success in the environment. As an example, polluted harbors are also organically enriched, thereby providing a greater amount of food to winter flounder, either directly or indirectly throtigh augmented prey populations. This could lead to Faster growth rates of flounder even in the presence of toxicants. Based on physiological information, pollutants have the potential to impair reprodtIction and there-fore reduce recruitment. The extent to which this actually happens in the field is not known. A num-ber of studies cited by Thurberg and Gould relate high pollutant concentrations to lowered reproduc-tive success. These include winter flounder exposed to PCBs in Long Island Sound and Atlantic cod exposed to oil spills in the North Sea. Thurberg and Gould state that such effects in the field would vary "erratically with time and site." If a pollution "signal" is occurring, one would predict that the decline in fish populations would be more pronounced in those species or populations that occur nearshore, at the higher end of any pollution gradient emanating from land-based sources. Although historically hearshore species were likely overharvested first before fishing effort moved fur-ther offshore, the present decline in fisheries has occurred both nearshore and offshore. We conclude that the major cause of low recruitment has been low initial spawning biomass related to overfishing. EFFECTS OF HABITAT LOSS AND D[IGRADATION ON GROtJNDFISF-I Destruction and degradation of large sections of coastal and nearshore habitats have occurred throtughout the New England coast since the arrival of European colonists. Even if habitat effects have not played a major role in the recent New England groundfish crisis, anthropogenic impacts on habitats could slow or inhibit the recovery of groundfish when restrictive fishing measures are implemented. Deegan and Buchsbaum (Chapter 5) reviewed impacts to finfish caused by losses of coastal wet-lands, hydrological alterations, dams., eutrophica-tion, damage from fishing gear. ditching for mosqtlito control, power plants, and exotic species. Like pollution, most habitat impacts on fish are indirect, in that they do not cause direct mortality themselves, but make the fish more susceptible to other sources of mortality, such as increased preda-tion on juveniles due to loss of hiding places. Such indirect impacts are therefore hard to quantify. There have been a number of difficulties in relating habitat changes to changes in fish poptIla-tions. First, we do not know under what conditions fish populations are limited by the availability of suitable habitats, even for those species for which habitat preferences are established. As an example, we do not know whether the loss of 30 to 50 per-cent of the precolonial salt marsh acreage has reduced populations of estuarine-dependent fish, since they may be more affected by other factors. On the other hand, recent studies of cod and hake suggest that there may be some critical habitats at particular life stages that are limiting (Auster and Langton, 1999; Lindholm et al., 1999). This was the rationale for the New England Fisheries Management Council's 1998 designation of a cobý ble habitat in Georges Bank as a "Habitat Area of Particular Concern" for juvenile cod. A second dif-ficulty is that habitat types that are important to fish are not necessarily obvious to uIs. It may be relatively easy to characterize the fish community and boundaries of a cobble area or an eelgrass bed, but the location of an offshore salinity discontinuity that may be important to fish larvae changes depending on the relative flow of rivers and tidal currents. A third problem is that it is very difficult to characterize all the potential habitat interactions that may affect a species. Habitat impacts on
I >* n cin ix predators. prey, and competitors may all influence tile population. Fourth and closely related to (3) is a general lack of knowledge of fish-habitat rela-tionships. Up until recently, the major focus of fisheries managers and fisheries researchers friom federal agencies has been on the population biology of individual species. not on ecological relationships. Before 1990. most of the well-documented studies of habitat losses and degradation were of coastal wetlands and shallow nearshore habitats because that was where the most obvious physical changes had occurred. In addition, the logistics for carrying out studies, primarily by university researchers who do not have ready access to off-shore fisheries research vessels, were easiest. In those parts of the United States and in Australia where fisheries are heavily dependent on estuarine and nearshore species, declines in commercial fish-eries have been directly linked to loss of coastal wetlands. Research by Deegan and her coworkers showed that eutrophication of coastal embayments results in ameasurable change in the fish commu-nities within eelgrass beds (Deegan and Buchsbaum, Chapter 5). Recent research on the impacts of fishing gear on benthic communities in fishing grounds further offshore has raised serious concerns about habitat changes that may at a minimum be affecting recruitment of certain species and under a worse 2 case scenario, altering the integrity of the entire marine ecosystem (see Dorsev and Pederson. 1998: Auster and Langton. 1999, Watling and Norse 1999; NRC 2002 for reviews). Changes in the physical structure of benthic communities as a result of the activities of draggers have been docu-mented in both nearshore and offshore waters of New England. Dragging disturbs physical and bio-genic habitat features that are attractive to various species of juvenile fish. Lindholm et al. (1999) and Olney and Boehlert (1988) suggest that loss of habitat structure, such as that which occurs during bottom dragging or dredging of seagrass beds, increases predation on juvenile fish. Three modeling efforts cited by Deegan and Buchsbaum suggest that habitat degradation does have an impact on some fisheries. In the Northwest Shelf region of Australia, dynamic models indicated that the abundance of some commercially impor-tant fish species were limited by the amount of suitable habitat provided by epibenthic animals that are prone to removal by bottom dragging. Boreman et al. (1993) concluded that increasing juvenile suir-vival of inshore winter flounder in the northeast United States through habitat restoration in combi-nation with reduced fishing pressure on adults results in a greater overall benefit to the population than reducing fishing effort alone. Based on a sim-ulation model, Schaafet al. (1 993) predict that destroying only I% of the estuarine habitat ofjuve-nile menhaden could result in a 58% decline in population levels after 10 years. TiE RoLE OF NATEURA\\L ENVIRONMENTAL F1.C-I.Irux-IrONS ON GROUNDFISH The suggestion that variations in natural envi-ronmental factors has had a severe impact on New England groundfish species was the basis for the application by Commonwealth of Mvlassachusetts for federal disaster relief for its commercial fishing industry in 1995. Recruitment does vary from year to year based on climatic and other ecological con-ditions, however Murawski (Chapter 2) shows that poor recruitment is not the cause of recent ground-fish declines. His simulation model suggests that poor recruitment may have had the effect of exac-erbating declines caused by overfishing, but that overfishing was clearly the major driving force. For a sustainably-m anaged fishery, exploitation rates should account for the potential for poor recruitment in any given year. Recruitment of yellowtail flounder has been related to seawater temperatures, based on a decline in recruitment and landings during a warm-ing period in the 1940s and 50s and a subsequent increase when temperatures cooled. The last major period of consistent change in seawater tempera-ture, however, was a warming in the early 1960s. Since that time seawater temperature has shown yearly variations but no consistent trend upward or downward that would likely affect recruitment of yellowtail flounder or any other species in a con-sistent way (Murawski, 1993). Changes in the amount of runoff from the Saint Lawrence River have been discounted as a cause of decline in cod (Frank et al., 1994). Even if there were clear-cut environmental trends that might impact the recruit-ment or migratory patterns of groundfish, one
SUNIM.-RN AND) (uCII>.fl,ýiONS 15 3 would expect that the changes would be observed in a variety of species and not just coincidentally in those species that happen to be heavily fished. Fisheries managers in their projections of New England groundfish populations have generally relied on the assumption of a constant level of instantaneous natural mortality (M), typically set at M=0.2. Habitat quality has never been factored into these models, perhaps because the high level of fishing mortality in recent years has made variations in natural mortality a minor factor in predicting Populations. With the decline in fishing mortality rates in the late 1990s and early 2000s under strict regulations, changes in natural mortali-ty and mortality associated with habitat degrada-tion will likely become a more significant factor in population trends. MUIrF'PI.E STRESSORS ANI) RECOVERY The biological community of the Gulf of Maine ecosystem has changed in a number of ways because of overfishing of groundfish (Witman and Sebens, 1992). Some species may experience rapid population growth once the strong influence of a limiting factor (i.e., overfishing in this case) is removed. This is particularly the case if, as sug-gested by Sinclair (1997), overfishing has not changed the basic structure of the biological coin-munity. On the other hand, the reduction of many populations to their present low levels may have changed the community dynamics such that certain species may no longer be able to achieve their for-mer abundance, at least in the short term. The populations of different marine species in New England are likely never in a state of equilib-rium in relation to each other. Natural changes in fish communities occur in response to long term and yearly climatic trends or as different species influence each other through competition and pre-dation. Species that are prey for cod, for example, may become more abundant because of overfishing of groundfish and then exert a controlling influence on future cod numbers by feeding on juveniles. One cannot assume that there is some predeter-mined level that a population trajectory will reach once a major source of mortality is removed, par-ticularly for an ecosystem that is subject to natural environmental variations over different time scales that are superimposed on human impacts, Myers et al. (1995) suggest that fish stocks in general can recover if the overfishing problem is addressed, however there is no.indication that the population of Atlantic cod off Newfoundland has returned despite many years of a fishing moratorium. The anticipated recovery of New England groundfish due to reduced fishing effort and closures of large areas provide an opportunity to better understand the effects of ecological factors that mnay regulate giroundfish populations. ANADROMOUS Fisll Moring (Chapter 3) makes it clear that over-fishing, pollution, and habitat degradation have all reduced populations of anadromous fish from their former levels of abundance in precolonial times. Anadriomous species were declining in southern New England as early as 1870., primarily due to dams and pollution, two products of the Industrial Revolution. Today, habitat degradation and poilu= tion still affect population trends. Blockage of migration routes by dams and other structures across rivers and streams has elim-inated access to large areas of potential spawning habitat. By 1950, damming of rivers had left less than 2% of the original habitat for Atlantic salmon in New England accessible to the fish. A recent survey of 215 coastal streams in southeastern Massachusetts documented 380 obstructions to fish passage, the majority of which are "manmade" dams (Rebeck et al., 2004). Many rivers now have fishways around dams, but these still are not as efficient in allowing fish to successfully migrate both up and downstream as are free flowing rivers. There have been efforts to remove dams that are no longer serving a useful function, such as the Edwards Dam on the Kennebec River in Augusta, Maine. Although dams have been the most serious fac-tor in declining anadromous fish runs, other habifat factors have also been of concern. These include increased water temperatures and siltation of spawning areas due to the removal of streamside vegetation, siltation caused by sanding of roads in winter, and algal growth on spawning sites due to eutrophication. Striped bass provide an example of an anadro-mous fish that in the past suffered from the effects
154 flqai of both overfishing and pollution. Overfishing in the 1970s and early 1980s led to severe population declines. The fish have now recovered well after a period of severe restrictions on both commercial and recreational fishing, so overfishing was clearly a ma)or factor in the decline. Moring also cites pol-lution reduction activities in the Chesapeake Bay region, the major spawning area along the east coast, as contributing to the recovery of the stock. Recent problems with other species of anadro-mous fish have been more difficult to characterize than those of striped bass. American shad and blue-back herring runs in Massachusetts increased until 1993 but have been declining since then for rea-sons that are not understood. Despite intensive efforts at restoration, Atlantic salmon runs to larger New England rivers are still very tenuous, and the Gulf of Maine population segment is now federally listed as endangered. Moring suggests that some as yet undetermined factor occurring when these fish are at sea may be the primary cause for the recent trends in these species. Declines in rainbow smelt runs throughout much of Massachusetts have been linked to site-specific habitat degradation (e.g. sil-tation, nutrient enrichment) in individual spawning streams. A modeling study cited by Moring pre-dicted that smelt can also be severely impacted by recreational angling. Since the decline in anadromous fish has been the result of a variety of factors, some of which are still mysterious, their recovery, will require a multi-faceted approach. Groundfish recovery is compli-cated because of politics, less so due to their biology. The assumption is that groundfish will recover if overfishing is stopped. In contrast, anadromous fish present both political and biological challenges. Recovery programs must include controlling over-fishing and mitigating land-based habitat alterations and pollution, but these still do not guarantee suc-cess due to ecological interactions that are not well understood but likely beyond human control. BIVALVE SHELLFISH DIFFICULTY OF STOCK ASSESSMENTS OF BIVALVES An evaluation of the relative importance of overfishing, pollution, and habitat loss and degradation to inshore bivalve populations is. clouded by the limited data available. Brousseau (Chapter 6) indicates that scientists cannot accu-rately assess the status of the three major inshore bivalve species harvested in Massachusetts (hard-shell clams, soft-shell clams and bay scallops) nor can they say whether these species are being over-fished or not. There is a lack of reliable population data and only limited quantitative understanding about the natural and biological factors that influ-ence recruitment of juveniles. Landings data for bivalves, although notoriously unreliable, suggest that there has been an overall decline in landings of hard-shell clams over the last twenty years. Total bay scallop landings have shown a great deal of year-to-year variability with no overall trends except for some losses in specific areas. There has been little overall change in landings of soft-shell clams. Landings data for bivalves are suspect because they are collected by individual towns with no con-sistent methodology or quality control. In addition, the abundance of the shellfish resource is only one of a number of factors that determine how much is landed. If the local economy is depressed or if shellfish prices are high, more people may turn to shellfishing to earn extra income, leading to an increase in landings. Declining water quality, which reduces the acreage of shellfish beds open to harvesting, may depress landings without influenc-ing the size of the population. Landings per unit effort, therefore, provides a better barometer of how the stocks are doing over time. There are other difficulties in trying to under-stand the status of inshore shellfish resources and how to manage them wisely. Traditional fisheries models based on finfish population dynamics do not work well for these bivalves because of the dif-ficultyvin defining what a stock is and thereby establishing a stock-recruitment relationship. There may be little relationship between the size of a local shellfish population and subsequent recruit-ment in the locality since the planktonic larvae may come from a larger functional population that encompasses a much larger region. Thus fishing on a small, local subpopulation may have little influ-ence on the future population size in that particular area. If this is true then shellfish resources are probably better managed at a regional level than town by town.
S..'DI-MMK\\ AND ( (-N( [AISIONS 1 ý5 It has been difficult to incorporate into models the tremendous yearly variation in recruitment that characterizes these bivalves. Variable hydrodynamic and climatic conditions likely' have a major effect on the. success of settling. Benthic predators may strongly affect the early' survival ofjuveniles. Sensitivity' analysis described by Brousseau indi-cates that population growth rates of a number of commercially important shellfish are more sensi-tive to changes in larval survival and recruitment than they are to adult survivorship or fecundity. ARE SOFT-SHELL CLAMS OVERFISI[ED IN MlASSAC1 IUStTTS'? Based on four Massachusetts towns that harvest soft-shell clams; A'va arenaria, almost exclusively, Brousseau showed that landings per unit effort fluctuated intensely from 1970-1995 without any consistent trends in either direction. There was also much scatter but no trends when landings per unit effort were plotted as a function of effort. Thus these particular data, admittedly limited, do not support the notion that soft-shell clams are being overfished. at least to the point where recruitment is being affected. EFFECTS OF Po'Ir'rUNTS ON BIvk\\ivi.s In Chapter 7 McDowell describes a range of physiological effects exhibited by bivalve mollusks living or transplanted into areas heavily contami-nated with organic contaminants and heavy metals. Moore et al. (1994), for example, found that the prevalence of a wide range of pathologies of Mya arenaria and Ilvtilus edilis (blue mussel) was strongly correlated with high levels of PCB con-tamination. Although direct population effects have not been documented in the New England region, a number of the physiological responses of some bivalves to lipophilic compounds, such as PAlis have implications for reproductive success. These include impairment of feeding, slower overall growth rates (which reduce reproductive output), developmental abnormalities, and degeneration of reproductive tissues. McDowell's research indicated that Mi'tihts edulis transplanted into highly PCB and PAH-contaminated New Bedford Harbor showed reduced reproductive effort and degeneration of oocytes compared to mussels transplanted into less contaminated areas. The interactions between population growth and contaminants are complicated by other environ-mental influences as well as human harvesting patterns. In a study of the impact of PAH concentra-tions on populations of Alva arenaria along a pol-lutant gradient in Massachusetts Bay, McDowell and Shea (1997) found that clams from the most contaminated sites differed in the timing of gamete development and had high levels of gonadal infla-mation and hematopoictic neoplasia, however pop-ulation growth rates as estimated from a determin-istic model were not directly related to contaminant concentrations. Predator and hydrological varia-tions had a strong influence on recruitment patterns regardless of contaminant levels. Recruitment of larvae into a contaminated area from a clean outside area may provide a periodic source of new individuals. As described, for groundfish, individuals settling in a contaminated area may grow more rapidly than those in a clean area due to organic enrichment, but they. may ulti-matly end up with impaired ability to reproduce. Clam flats are closed in most urbanized coastal communities not because of toxicants but because of high levels of fecal coliform bacteria. Populations of soft shell clams may be quite abundant in these areas despite the fecal contamination. Fecal col-iform contamination is a human health rather than an ecological concern, unless, of course, it co-occurs with heavy metals or toxic organic com-pounds. Such closed clam flats could serve as a source of new recruits to uncontaminated areas. EFFECTS OF HABITAT. LOSSES AND DEGRADATION One of the best examples of the impact of habi-tat loss on a commercially important marine animal is the relationship between eelgrass and bay' scallops described by Deegan and Buchsbaum (Chapter 5). The wasting disease epidemic of the 1930s, which wiped out most of the eelgrass along the east coast of the United States, resulted in an almost immedi-ate crash in bay scallop landings (documented for Chesapeake Bay), which lasted until the eelgrass began to recover. Eelgrass fluctuations still occur naturally and due to eutrophication, and these still impact local populations of bay scallops.
1 56 n :l*n'i-There is little information on the impact of habitat losses on other species of bivalves. The historical filling of tidal flats in places like Boston's Back Bay undoubtedly caused losses of suitable habitat for soft-shell clams. Such widespread filling is now limited by wetlands protection regulations, however small scale losses from legal dredging. dock and pier construction. and illegal activities still are likely to occur in the region. THE ROLE O1 MULTIPLE FACTORS Dramatictfliuctuations in adult bivalve popula-tions are probably natural in the northeast, and these may mask any affect of overfishing, pollu-tion, or recent habitat changes. Both Brousseau and McDowell suggest that populations of bivalves are more sensitive to changes in larval survival and recruitment than to variations in adult survival, thus anything that reduces the growth and.survivor-ship of bivalve eggs and larvae could have serious population consequences. The timing of a habitat alteration, whether human induced (e.g., siltation., dragging. remobilization of toxicants) or natural (e.g., drought, storms, annual temperature fluctua-tions, etc.), is probably critical during the period when larvae are in the water and probably lead to the yearly fluctuations in recruitment. It is questionable whether hutnan-induced changes in habitat have currently occurred on a wide enough spatial scale to affect recent recruit-ment in any way, except locally. What is needed to better manage inshore bivalves is to understand factors that affect larval recruitment. to establish the appropriate geographical boundaries of stocks and to collect more reliable population data. This information will enable us to understand better the impact of fishing, pollution, and physical changes in habitats oil these inshore bivalves. LOBSTERS ARE LOBsTrERS OVERFISHED? Steneck (Chapter 8) describes a debate about the status of American lobsters, the most valuable fishery in New England from an economic perspective. Although the lobster fishery is not cur-rently in as bad a condition as groundfish, lobsters are still classified as overexploited by NMt-FS due to high fishing mortality (NMFS, 2001 ). NMFS bases this on an extremely high rate of fishing mortality and the heavy dependency of tile fishery on new recruits. They define the recruitment over-fishing level for lobsters as the fishing mortality rate that results in a reduction of the production of eggs per recruit to 10% of that of an unfished pop-ulation. Steneck presents data from Maine showing that the total tonnage of lobsters landed increased from the mid 1980s throtilg the 1990s with no evidence that the brood stock declined. Despite increased fishing effort oni this species and the decline in the average size of individuals landed, the annual land-ings petr effort ratio increased in recent years. Thus he disputes whether recruitment overfishing is occurring now. In his analysis of data from Maine, Steneck relates periods of lower lobster abundance to lower water temperatures that reduces the success of post larval settlement. Given tile extremely high rate of fishing for lobsters, it is surprising that such an environmental signal is detectable. In an analysis of a larger data set, Drinkwater et al. (1996) did not find the same specific relationship between higher seawater temperatures and the increased catch of lobsters from Newfoundland to the Mid-Atlantic Bight during the 1980s and early 1990s. Nonetheless, these authors still propose that a real increase in lobster abundance during this period was related to some as yet undetected environmental control. Steneck also questions the accuracy of popula-tion estimates and the stock recruitment relation-ship used to conclude that lobsters are overfished. Hle argues that it is very difficult to get accurate statistics on the stock-recruitment relationship, nat-ural mortality, and the size of the populations throughout the entire range. In addition, the models that NMFS uses in their assessments do not factor in ecosystem changes. The overfishing of lobster predators, such as groundfish, and an increase in kelp habitats attributed to the development of a fishery for sea urchins (a major kelp herbivore) have favored lobsters in recent years. Steneck suggests threats other than fishing are equally or perhaps more important to this crustacean.
SUMM:MI-R' AND 'M {\\SLI[NS 157 These threats include degradation of the rather lim-ited cobble habitat required by newly settled juve-niles and the negative effects of pollution. Fie also raises the issue of protecting a major part of the broodstock (i.e. large females that may inhabit deepwater refugia that are not fished with traps). These may be the major source of eggs and have been. up to recently, relatively free from fishing pressure. AN ALTERNAfE PERSPECTIVE In contrast to Steneck, other scientists, particu-larly those from the National Marine Fisheries Service, have been concerned that a fishery so con-centrated on new recruits could be devastated if there were a few poor recruitment years in a row. From their perspective, it is necessary to set the overfishing definition at a precautionary level as a buffer against changes in environmental conditions that, in concert with fishing pressure, could lead to a population crash (NI. F'ogarty, pers. comnm.). The 10% egg production level should be seen in that context rather than a threshold below which lobster populations will definitely collapse. The trend of the fishery in recent years toward a smaller average size of lobsters and increasing dependency on new recruits is evidence for growth overfishing and is similar to what was observed in groundfish before the collapse of a number of those stocks. There may be long-term conse-quences to the populations of a fishery-induced truncation of age structure, at least in nearshore populations where most individuals only have the chance to spawn once before they are caught. The large lobsters that currently contribute most to the broodstock would not be limited to deeper offshore habitats if it were not for overfishing nearshore. There are also economic consequences of the current fishing pressure on lobster. The overall yield of lobsters is not high as it could be if lob-sters had a chance to grow to larger average sizes under lower fishing rates. NMFS believes that higher long term yields and a healthier lobster pop-ulation would result from a reduction in the amount of fishing effort on lobsters. LOBSTERS VS. GROUNDFISH It is interesting to speculate whether the argu-ment Steneck presents about the limited ability of lobster statistics to accurately allowa definition of overfishing can also be applied to groundfish. Do we accurately know the stock-recruitment relation-ship and do we have an accurate measurement of stock sizes and accurate estimates of natural and fishing mortality? The data presented by Murawski (Chapter 2) indicate that for many groundfish species, we have a good idea of the size of the spawning stock biomass necessary to produce an adequate number of potential new recruits to the fishery. The NMFS trawl surveys undoubtedly por-tray the populations and the age structures of the various groundfish species with a much greater degree of confidence than is now possible for lob-sters. As a consistent, repeated survey, the trawl surveys do provide an index of lobster abundance, however the catch per tow is very low on lobsters leading to much higher statistical variability than one would expect for groundfish. The problem is that trawls cannot sample in those habitats where the nreatest densities of lobsters are likely to be found. i.e., nearshore rocky areas where fixed gear is in place and catch efficiencies are low. One important way in which lobsters differ from groundfish is in the long time lag between egg production and growth to reproductive age, about six to seven years in lobsters, but much less in most groundfish species (i.e., 2-3 years in cod and haddock, 3-4 in yellowtail). Thus, it takes a number of years before anything that influences juvenile survival of lobsters is reflected in the catch. POLLUTION AND HABITAT IMPACTS ON LOBSTERS Pollution is not likely a major factor control-ling lobster populations over the whole region, however it can be locally important and of concern to human consumers. Oil spills can have devastat-ing, localized effects, as illustrated by the 1996 North Cape oil spill in Rhode Island (NOAA et al., 1999). For chronic pollutants, the cobble habitats preferred by juveniles tend to be areas that are rea-sonably well flushed and therefore relatively clean. Adults that occur in soft-bottomed urban harbors are more exposed to toxic organic compounds and
f~I heavy metals. There may be some potential for a localized effect on reproduction, but whether that causes population impacts, even within urban liar-bors, is unknown. The habitat issue of most concern to Steneck (Chapter 5) is the potential for damnage to juvenile cobble habitat due to sedimentation and mobile fishing gear. If the availability of this habitat is really limiting lobster populations. then its protec-tion should be a major management goal. OTHER GROUPS OF FisiI AND SIIELLFISII The reports in this volume focused on New England groundfish, anadromous fish, lobsters, and nearshore bivalve shellfish. Our intent was not to provide a survey of all ecologically and commer-cially important species in New England, but to explore the question of the relative importance of overfishiing, pollution, and habitat destruction to representative groups for which there are some data on all three factors. For the sake of complete-ness, here is a brief look at other groups and the issues they raise. HIGHLY MIGRArORY PELAGiC Fisn The recent steep declines in populations of a number of pelagic "highly migratory" fish-- Western Atlantic bluefin, bigeve and albacore tuna, North Atlantic swordfish, and large coastal sharks-are due to intense overfishing. These are currently classified by the National Marine Fisheries Service as overfished (NMFS1 2001). Their pelagic, migratory life histories make it diffi-cult to connect their population fluctuations with habitat or pollution-related factors. The relatively long life span of these species tends to mask impacts, if any, of natural environmental variations on populations. The prime focus of managers and scientists has been on managing fishing effort and understanding populations dynamics and demogra-phy. (NMFS, 1997, 1998) without any emphasis on habitat-related factors. Less is known about the environmental factors that influence larval recruit-ment in these pelagic fish than in groundfish or anadromous species. At the moment, no hypotheses have been proposed that suggest that anthropogenic factors other than fishing mortality is influencing the populations of these species. SEA SCAL,\\CPS Fishing pressure on sea scallops, Placopeclii, mnagellanicus, is intense. Some impacts of natural environmental fluctuations on the success of year classes have also been identified. Variations in the success of recruitment of different year classes have been related to differences in the "tightness" of the autumnal gyre in Georges Bank (Packer et al., 1998). Sea scallops also occur nearshore, par-ticularly in the northern part of the Gulf of Maine, but there has been no research to indicate whether coastal habitat degradation has had any influence on nearshore populations. The rapid increase in the population densities and sizes of scallops in areas of the Gulf of Maine and Georges Bank closed to all gear types in the late 1990s due to the ground-fish crisis shows that sea scallop populations have the potential to respond very rapidly when freed from fishintg pressure in a protected area. COMPETITION ANt) TROiHIic I Nt.IE ACIIONS Herring and mackerel, along with other smaller pelagic organisms. such as krill, ate considered important components of the marine food chain since they serve as forage for larger fish, marine mammals, and marine birds. Fishing pressure on herring has been cited as the cause of the alteration of the biological community that resulted in an increase in sand lance in the 1970s (Sherman et al., 1981). The mechanism was presumably competi-tion between the two species for food. In recent years, both herring and sand lance have co-occurred in abundance in the Gulf of Maine, leading Sinclair (1997) to conclude that sand lance abun-dance is independent of that of Atlantic herring. Both vary according to environmental factors rather than from food chain relationships. The potential for increasing the commercial catch of herring and krill has raised the issue of potential trophic impacts of the large-scale removal of these species if they are targeted for increased fishing (Partington, 1996). Along with clarifying the actual status of herring populations, trophic modeling will be needed. A related topic is how predation by marine
SIIMMAKY AND CON\\.LUS[ONS I 5C mammals and birds affects the recovery of fish. Moring (Chapter 3) attributed the loss of seven percent of downstream migrating Atlantic salmon smiolts in the Penobscot River to predation by cor-morants. One modeling effort attributes much of an increase in natural mortality of juvenile cod in the Gulf of Saint Lawrence to predation by the rapidly increasing population of gray seals (Sinclair, 1997). Although the actual percent mortality due to the seals is uncertain, predation by the seals now likely exceeds that by fishing. Sinclair pointed out that the potential for predation by seals is much less in the Gulf of Maine due to the much lower abun-dance and diversity of seals compared to the Gulf of Saint Lawrence. In sum, although a number of studies have addressed this subject, there is no solid evidence that mammalian and avian predators in the Gulf of Maine and Georges Bank have caused the decline in any fish species or will hinder recovery. CONCLUjSIONS: OVERIISHING VS. POLLUTION vs. HAlBirIF DEGRADATION M4an had always assumed that he was ,nore intelligent than dolphins because he had achieved so much... the wheel, New Ibrk, wars, and so on, ivhilst all the dol-phins had ever done was muck about in the water having a good time. But con-versel y the dolphins believed themselves to be more intelligent than man for pre-cisely the samne reasons. -Douglas Adarns, 1984 I. Overfishing is by far the greatest cause of the decline in groundfish species in New England. The "signals" from pollution and other forms of habitat degradation have been impossible to detect, given the "noise" from overfishing. Managing fishing effort is the single most important key to the recovery of these ground-fish stocks.
- 2.
There have been no documented impacts of pollution on populations of fish and shellfish in New England, although reproductive impair-ment related to toxicants is well established, based on physiological studies. One would expect population impacts to be most obvious in heavily polluted urban harbors.
- 3. Studies from otherregions that have simultane-ously examined habitat quality and fishing mortality have shown that habitat quality can be very influential on some fish populations.
- 4.
At low population levels, habitat effects could have a strong impact on recovery of ground-fish, even if such impacts were not the initial cause of declines. The patterns of recovery will also be affected by any changes in the biological community that have occurred as a result of overfishing.
- 5.
Habitat loss and degradation (including pollu-tion) have been strong influences on popula-tions of anadromous fish in New England. Overfishing has also been a significant factor for some species. Some unknown factor(s) when these fish are out at sea is apparently contributing to recent population declines and lack of recovery of some species.
- 6.
Population fluctuations in bivalve shellfish are more strongly related to interannual variation in recruitment than to fishing pressure. We can-not presently factor out the effects of pollution, habitat degradation, and natural environmental variation on recruitment processes.
- 7.
Despite heavy fishing pressure, lobster popula-tions have remained high. Natural environmen-tal factors that affect settling by larval lobsters may have a stronger impact on lobster popula-tions than fishing mortality. There is disagree-ment among lobster biologists about whether lobsters should be considered overfished.
- 8. Ecosystem-level research is needed to under-stand the impacts of habitats and other ecologi-cal factors on commercially important fish and shellfish. Some research topics of special importance to the questions raised in this book:.
habitat relationships of groundfish, particu-larly how habitat alterations by fishing gear impact fish populations, population impacts of pollutants causes of presumed mortality of anadro-mous fish at sea. stock-recruitment relationships in bivalves and lobsters.
ONE FINAl. TilouclT - HAVE Wi: AcilIvEEI) -ril Gox.,s SEr OUT FOR rlfis BooO? Conservationists ar-e nolot'ious fo)r their dissensions. Superficially these seem to add up to mere coniusion. but a more careful scrutiny reveals a single plane of cleavaU.e Como177n017 to man17y spJecialized fields. I7 each field one group (A) regards the land as soil, and its function as commodity-production; another group (B) regards the land as a biota, and its /mac'ion as sometlhing broader: itow miuch broader is achnittedlv in a slate of doubt and confitsion. -Adio Leopold. 1949 As stated repeatedly throughout this work. our major purpose has been to evaluate the relative importance of overfishing, pollution, and habitat loss and degradation on finfish and shellfish popu-lations, focusing on the Gulf of 'Maine region. The degree to which we have succeeded must be judged, ultimately, by our readers. While acknowledged early in our discussion (Chapter 1), it is clear that finding a common "cur-rency" by which scientists who consider these issues can quantify the extent of the impacts they study relative to the other two constraints is diffi-cult. Given the specialized nature of scientists, it is not surprising that those who study the physiologi-cal impacts of toxicants do not generally feel com-fortable making statements about population impacts and vice versa. The data on the population impacts of toxicants and other types of habitat degradation are quite limited at this time, hence the reluctance on the part of those working on those subjects to speculate. Nevertheless, we have suc-ceeded in advancing the common "currency" concept. Although differences in scientific discipline have much to do with it, other factors make it hard to compare fishing impacts, pollution, and habitat degradation. The spatial scale of these major cate-gories of impacts differ. Toxic effects, or at least our ability to detect them, are restricted for the most part to certain urban "hot spots" whereas fishing impacts are more widespread. The spatial scale of fish populations is likely much larger than the scale of toxic impacts. Habitat losses have been widespread, but in scattered localities, such that adequate refugia from those impacts may (or may not) exist. There are also questions about the ade-quacy of population data for certain groups of organisms, particularly nearshore bivalves and lob-sters. If we do not have a firm grasp of population numbers, demography, the spatial scale of a stock, and stock-recruitment relationships, then it will be very difficult to identify the major constraint on that population quantitatively. Complicating the matter is that the natural and human-induced con-straints themselves also varvover spatial and tem-poral scales. Nevertheless, we have succeeded in attempting meaningful comparisons in light of dif-ferential spatial and temporal scales. To the extent that models were discussed that attempted to evaluate the population impacts of factors other than fishing mortality, our effort was also successful. Murawski (Chapter 2) showed the dominance of overfishing as a factor because his. population models require no further inputs other than fishing mortality to explain the current low populations of many groundfish species in New England. Deegan and Buchsbaum (Chapter 5) described models indicating that habitat considera-tions as well as overfishing have the potential to influence at least some populations of fish. The need for more holistic modeling.to resolve the rela-tive importance of habitat and fishing pressure is obvious, particularly now that there has been such a large management interest in protecting fish habitats. We believe that the primary value of this work is that it put the discussion of multiple stressors on fish and shellfish populations in one volume. It forced the authors and editors to try to relate these factors. Hopefully, future efforts based on more comprehensive data collection and increasingly sophisticated holistic models will provide more complete answers and will aid in the achievement of sustainable fisheries and a healthy marine ecosystem. LITERATURE CITED Adams. D. 1984. So Lone and Thanks for all the Fish. New York: Harmony Books. Auster, P. J. and R.W. Langton. 1999. The effects of fishing on fish habitat. In: L. Benaka (ed.). Fish Habitat: Essential Fish Habitat
STJ~NI~liti AND C:ON, LiSIONS 161 I"F I-I and Rehabiliation. American Fisheries Society, Bethesda, Mlaryland. Horcitan. J.. S.1 Correia and I). 13. Withereli. 1 9193. Et'.ects of chanCes in aLc-0 survival and fishing mortalitv oil egg produc-tion of wintcr fiounder in Cape Cod Bay. Arn. Fish. Soc. Syrip. 14:39-45. Dorsey. E. and J. Pederson (eds.). 1998. Effects of Fishinq Gear on iie Sea Floor of New Fn'land. Conservation Ilaw Foundation, Boston, MA. 168 pp. Drinkwater. K.F.. GC. Harding, KH. Mann, and N. Tanner. 1996. Temperature as a possible factor in the increased abundance of American lobster. Homarnis americantus, during the I 980s and carly I990s Fisheries Oceanogralihy 5:176-193. Frank. K.T., K.F. Drinkwater. 1994. Possible causes of recent trends and fluctuations in Scotian Shelf Gulf of Maine cod stocks. IC1ES Marine Sei. Svmposia 198:110-120. Leopold, A. 1949. A Sand County almanac and sketches here and there. New York: Oxford University Press. Lindholtt J.B., P. J Auster. and L.S. Kaufman. 1999. Halbitat-medi-ated survivorship of juvenile (Il-vear) Atlantic cod Gadus iiiorlihoa. Mar FEcol. Proer. Ser. 180:247-256. McDowell. J.E. and D. Shea. 1997. Population processes of Ma are-oaria from contaminated habitats it Massachusetts Bays. Final Report to the Massachusetts Bays Program. Boston, MA Moore. Mi.J., R.M. Smolowitz, D.IF. Leavitt and J.3. Stegeman. 1994. Evalttation of Chemical Contaminant Effects in the Massachusetts Bays. Final Report to the Massachusetts Bays Programn, Boston, MA. Murawski, S.A. 1993. Climnate change and marine fish distributions: Forecastinitg from historical italnocy. I Trans Amrci. Fish. Soc. 122: 647-658. Myers. R.A., NTI Bariowman, J.A. Hutchings and A.A. Rosenberg. 1995. Population dy natics eofexploited fish stocks at low popu-lation levels. Science 269 1106-1108. NMvIS (National Marine Fisheries Service). 1997. Issues and Options for the Management of'Atlantic Highly Migratory Species. Scoping Docutment. Highly Migratory Species Management Division. Off. Sust. Fisheries, NMFS, NOAA, US Dept. Comm. Silver Spring. MD. NMFS (National Marine Fisheries Service). 1998. Comprehensive Research and Monitoring Plan lbe Atlantic Highly Migratory Species. Highly Migratory Species Management Division. Off Sust. Fisheries, NMFS, NOAA, US Dept. Comm. Silver Spring, MI D. NMFS (National Marine Fisherties Service) 2001. Report to Congress. Status of fisheries of the United States. NMFS, NOAA, Silver Spring, MD. 127 pp. NMFS (National Marine Fisheries Service) 2004. Stock Assessment aand Fisheries Evaluation (SAFE) Report for Atlantic Highly Migratory Species, 2004. NMFS, NOAA, Silver Spring. MD. 67 pp. NOAA (National Oceanic and Atmospheric Administration), Rhode Island Department of Environmental Management, and United States Fish and Wildlife Service. 1999. Restoration plan and environmental assessment for the January 19, 1996 North Cape oil spill. National Oceanic and Atmospheric Administration. NRC (National Research Council). 2002. Effects of Trawling and Dredging on Seafloor Habitat. Committee onl Ecosystem Effects of Fishing. Ocean Studies Board. National Academy Press. Washington D.C. 136 pp. Olney, i.E., and G.W. Boehlert. 1988. Nearshore icthyoplankton asso-ciated with seagrass beds in the lower Chesapeake Bay. Mar. Ecol. Prin. Ser. 45:33-43. Packer, D., L... Cargnelli, S. Grisebach, S. Shumway and E. Weissberger. 1998. Essential Fish Habitat Source Document, Sea Scallop, Placopectin magellanicus. Life Ilistory and Habitat Requirements. NEFSC, NMFS, Highland, NJ. 37 pp. 'artington, I'.FI. 1990, Pa'el remiarks: Contemporsry management issues reCuILiring' scientific research. In: G.T. Wallace and F.. Braasch (eds.). Pioceedintus oftile Gulft" of Maine Elcosystet Dynattmics Scientific Svnmpositimn and Workshop. RARGOM Report 97-1. Pp, I-3 Pinchot, G: 1947. Breakin" New Ground. New York: Harcourt, Brace. Rebeck. K.L.. RD Brady, K.D. Mcl..aughlin. and CG. Milliken. 2004. A Stirvey ol'Anadromous Fisl l'assaee il Coastal MIassachltLisetts P'aet I, Southeastern Massachusetts. Commonweath of Massachusetts, Massachusetts Division of Marine Fisheries. Pocasset. MA_ Technical Report fR-I 5. Schaaf, W. E., D. S. Peters, L. Coston-Clemients, D. S. Vaughn and C. W. KroUsC. 1993. A simenulat it model of how lile history strate-gies mediate pollution effects on fish populations. Esttaries. 16:697-702. Sherman, K., C. Jones, L. Sullivan, W. Smith, P. Berrien and L. Ejsymont. 1981. Congruent shifts in sand eel abundance in west-eri and eastern North Atlantic ecosystems. Nature 291:486-489. Sinclair. M. 1997. Recent advances and challenges in fishery science In: Proceedings of the Gilf o1' Maiine Ecosystem Dynamics Scientific Svinlposiuiti aind \\Vorkshop. GT. Wallace and 1. Braasch (eds.). RARGOM Report 97-I. Pp. 193-209. USEPA (U.S. Environmental Protection Agency). 2004. Fish con-sutmption advisories, http:/lwwwvetpa.gov/mercue/'advisories.htil last accessed 2/24/05. Wahle, R. A. and R. S. Steneck. 199 1. Recruitment habitats and nurs-cry grounds of the American lobster tloniaris americalls: A deiographic bottleneck? '.Mar..col. Proi,. Ser. 69:23 1-243. Watling, 1.. and E. A. Norse (eds.) 1999. Special section: Eflects of' mobile fishinc gear oit marine benthos. Conserv Biol. 2:1178-1240. Witman, J. D. and K. P. Sebens. 1992. Regional variation in fish pie-dation intensity: A historical petspective it tile Guelf of Maine. Occoloziia 90: 305-15
162
MIANAGEMNT SIMPIILICAI IONS 163) Chapter X Management Implications: Looking Ahead JUDITH PEDERSON Massachusetts Institute of Technology Sea Grant College Program 292 Main Street, E38-300 Cambridge, MA 02139 USA WILLIAM E. ROBINSON University of M1assachusetts Boston Department of Environmental, Earth and Ocean Sciences (EEOS)l 100 A'orHsseli Blvd. Boston, MA 02125 USA Ninetv percent of the marine fish comes fom ithe third of the oceans near land. -Peter Weber; 1994 Now would I give a thousand firlongs of sea for an acre of barren ground. -William Shakespeare, 1623, The Tempest 500000 -o 4000 000 3000000 2000000 1000000 A growing body of evidence has documented the accelerating decline of the oceans' most pro-ductive fisheries, a trend that is amply chronicled in the northwestern Atlantic (NOAA, 1998; FAO, 1997; NRC, 1998; Figure 10. 1). Aside from the obvious concern with landings and the societal impacts to the fishing community, the decline, if prolonged, will continue to elicit sweeping ecologi-cal consequences. Yet, over the past couple of decades, ecosystem considerations have been over-shadowed by the fishing industry's perspective and 0 i 1I 5 ] 4l I i II I I H II ] q I II q 1I II 1i9 0 Ii4 I I 9I86I Ii 1 990 1i 94 1956 1954 1958 1962 1966 1970 1974 1978 1982 1986 1990 1994
- Other groups o 31 -Flounders,hali buts,soles,..
- 34-Jacks, mullets, sauries,...
- 35-Herrings.sardinesanchavies 2 56-Clams, cockles, arkshells..
o 37-Mack.,snoekscutlassfishes IS 33-Redfishesbasses,congers,.. S 32-Co ds, hakes. haddocks,... Figure 10.1. Total landings (tons) of groups of marine resources from the northwestern Atlantic Ocean over the period 1950 - 1994 (FAO, 1997). Different hatch patterns distinguish different ISSCAAP fisheries groups. Peak landings in the late 1960s was principally due to ISSCAAP Groups 32 and 35.
1 64 IVi)ERSO>N & ROBII NSON needs. Stock assessment models, the mainstay of commercial fisheries management, are based on the population level of biological organizationl-- individual species of commercially important fish and shellfish---and are not based on species inter-actions and ecosystem dynamics (Applegate et al., 1998). Our intent with this volume was to compare the effects of overfishing, pollution and habitat alteration on fisheries and identify possible new approaches to managing fisheries and ecosystems that integrate these factors. We have only been par-tially successful in broadening the scope of this debate with a "common currency" that could allow us to weight the contributions of these three impacts on fisheries' declines. We are limited because the scientific information is either lacking or too fragmented to allow us to rank the relative strengths of each contributing factor in a definitive, unambiguous way for all species. Nor is there a preponderance of models that could guide us in this endeavor. As we look forward, the main chal-lenge to fisheries managers is the integration of ecological concepts, human activities, and social and economic considerations into sustainable fish-eries management. Ecosl'sTErN APPROACH The Magnuson Stevens Fisheries and Conservation Act of 1996 (Sustainable Fisheries Act; SFA), attempts to institute a more ecosystem-based regulatory approach to fisheries management than has been the case in the past. In practice, how-ever, emphasis continues to be on single species, especially specific finfish, lobsters and scallops, and to a lesser extent on individual anadromous fish, squid and shallow water bivalves. This approach neglects other components of the ecosys-tem, upon which commercially important species often depend for food and refuge (Applegate et al., 1998). Some ecological shifts that may have already affected marine fisheries have been reported, but most have gone undocumented. One dramatic change has been the loss of several top predators and their replacement with humans who have hunt-ed mammals, birds, and top fish predators or have altered their habitats. Over the past two to three centuries, some fish predators such as marine mammals (e.g., harbor seals, Phoca vitudina con-color) and a number of sea birds (e.g., Great Auks, Pinguinus impennis) were hunted to very low pop-ulation levels or extinction (Williams and Nowak, 1986). These large, top piscivores may have shaped species distribution and abundance. Recent population increases of other fish predators, such as striped bass (Morone saxitilis) and cormorants (Phalacrocorax spp.), may also be impacting the marine ecosystem, at least locally. Humans, also a top predator. affect even non-targeted fish species. Barndoor skate, Raja laevis, caught incidentally as bycatchand discarded, were once plentiful in the northwest Atlantic, but are now thought to be on the brink of extinction due to bycatch (Casey and Myers, 1998). Both the diver-sity and complexity of benthic ecosystems have been markedly reduced in areas subjected to repeated bottom trawling and dredging (Dorsey and Pederson, 1998). Industrialization and coastal development have significantly increased pollution loading and altered estuarine habitats at unprece-dented rates. All of these combined impacts have had and will have lasting effects on marine and coastal ecosystems, in addition to adversely affect-ing the fisheries of this region. Overfishing leads to yet another set of ecologi-cal consequences. As a fish stock declines, fisher-men switch to other species that are typically lower down the trophic level than the original species. In the northwest Atlantic, for example some fisher-men are switching from gadoids and other ground-fish to clupeids (fish that feed on plankton and are more abundant) (NEFSC, 1998). This trend, termed "fishing down the food web" (Pauly et al., 1998), has been documented in all mature fisheries worldwide over the past 45 years. Other fishermen have switched to less utilized groundfish (e.g., from gadoids to dogfish and monkfish). While the shift initially leads to increased catches, it is soon followed by the decline of the new fish stock. This pattern of exploitation is inherently unsustainable, and leads to far-reaching ecosystem changes due to the disruption in trophic interrelationships. Our current pattern of stock exploitation has one additional ecological implication. Somehow in the discussion of fisheries' decline, a basic ecologi-cal tenet that productivity of the oceans is finite has been lost or neglected (Ryther, 1969; Holt, 1969; Russell-Hunter 1970; Mann 1982; Mann and
MIANA(uENI EN"I NI 1PLICAriONS; 165 Lazier 1991). Primary production has narrowly cir-cumscribed limits, that, in turn, modulate the pro-duction of fish and shellfish that are harvested for human consumption. The rise in total fish catch over the past several decades masked the overex-ploitation of individual fisheries. As early as 1969, however, scientists were predicting an upper limit to fish productivity and expressed concern that fisheries were declining (Holt 1969; Ryther, 1969), but the switch to new and underutilized species and the incremental contribution from maricul ture tended to allay these concerns. Current estimates indicate that world marine fish production will probably peak at about 93 million tons (exclusive of a sig-nificant expansion of mariculture), only 10 million tons higher than today's landings (FAO, 1997). This maximum production can only be sustained if current overexploited and fully exploited fisheries are regulated for sustainability (World Resources Institute, 2000). The authors of this book have identified numerous research needs that should be filled to support informed management decisions (Tables
- 10. I and 10.2). Many of these recommendations have been proposed previously (MA DMF, 1985; MA MRCC. 1987; Buchsbaum et al., 1991; FAO, 1997; NRC, 1998, 1999), and would be anticipated by our readers. Most of these recommendations need no introduction or detailed explanation. Four recommendations that have not been given suffi-cient consideration by fisheries managers serve as a framework for achieving sustainable fisheries as presented below: (1) adoption of the precautionary approach; (2) the need for an ecosystem-based fisheries science; (3) developing new models; and (4) the adoption of adaptive management principles.
TIlE PRECAUTIONARY APPROACH In the face of uncertainty about potentially irreversible environmental impacts, deci-sions concerning their use should err on the side of caution. The burden of proof should shift to those whose activities potentially damage the environment. -Robert Costanza et al., 1998 Table 10.1. General categories of research needs that would assist and improve scientifically-based fisheries nmanagement. Recommended research needs and management approaches would address all four of the fisheries discussed in this volume. Improving our understanding of ecosystem processes as they relate to fisheries productivity " Make better use of historical data in describing trends of relationships between onshore and off-shore stocks and transport of pelagic larvae and life stages. " Quantify effects of contaminants on populations and relate to other impacts. " Quantify effects of habitat degradation and relate to other impacts. Developing an ecosystem-based fisheries science, including a new suite of models that can be used to forecast changes " Integrate anthropogenic changes with natural pro-cesses in models. " Include environmental fluctuations (e.g. weather, salinity, runoff ) and trends (e.g. global warming) into holistic models " Improve calibration and verification of models. " Develop models into forecasting tools for managers. Implementing new management approaches that support sustainability of valued fisheries " Incorporate the Precautionary Approach into fish-eries management " Utilize Adaptive Management techniques " Determine optimal spatial scale fornmanagement plans; eliminate management based solely on polit-ical boundaries. " Integrate natural history information into policy development and fisheries management. " Develop new electronic data analysis systems, interfacing geographic informiation systems, histor-ical data sets, the databases that exist in various agencies and organizations. " Test the effectiveness of marine refugia and management closures on fisheries stocks and productivity. " Characterize and define essential fish habitats and evaluate the causes and extent of alteration.
- Improve population estimates for species of interest integrating recommendations from academia, fishermen and managers.
166 ['LD)RSON &s ROBIN\\SON Table 10.2. Specific research needs and management options identified by the contributors to this volume.
- a. Research Recommendations Groundfish Anadromous Lobster Bivalve fish Improve current stock assessment X
X X X Develop new integrative, holistic models X X X X Improve understanding of population level effects of contaminants X X X X Evaluate contaminant effects on reproduction X X X Detennine the importance of endocrine disrupters on reproduction X X Evaluate effects of biotoxins on mortality X Identify factors at sea affecting mortality X Evaluate predation pressures (e.g. bird, crab, marine mammal) X X X Develop models relating land use to populations X X Identify stock and substock size to improve understanding of population dynamics Develop predictive models and verify with data X X X X
- b. Management Recommendations Reduce fishing effort to increase spawning stock biomass X
X Enforce regulations, closures and management efforts X X X Develop and implement a management plan for herring and mackerel Develop shellfish management plans X Develop management plans for restoring in-stream habitats X Develop and implement management plans in conjunction with X X watershed groups Create management units based on appropriate scales X Focus on research to evaluate broodstock trawling on lobsters X Develop a plan for protecting juvenile lobster habitat X Characterize the lag time between adverse or favorable effects on life history stages Determine whether predators are increasing or decreasing X X Develop management options for protecting habitat X X X X The Precautionary Principle calls for precau-tionary actions in response to potential threats to the environment or human health, even if causality has not been scientifically established (VanderZwaag, 1994). It is often interpreted in exclusion of the economic and social factors that managers must also consider when making their decisions. Because the language of the Precautionary Principle is rather vague and moralistic (Bewers, 1995), it has proven difficult to incorporate into policy decisions. Strict application of the Precautionary Principle would preclude any action unless it could be.proven that the action would be environmentally benign. Such an extreme approach is scientifically unjustifiable, since the scientific method can never be used to prove that harm is impossible. In contrast, scientific analyses are used to assign probabilities to various actions, and to estimate the uncertainty around these probability values (e.g., a 40% probability of a 20% change). In order to include scientifically justified estima-tions of risks, strict adherence to the Precautionary Principle is being replaced by a more workable "precautionary approach" that includes scientific justification of estimated risk (VanderZwaag, 1994; Bewers, 1995). The precautionary approach, which
NI ANAG~ENlICNI' I NIVII.CAIION5 167 implicitly recognizes that there is a diversity of ecological as well as socio-economic situations requiring different strategies, has a more acceptable "image" and is more readily applicable to fisheries management systems (FAO, 1994). The precautionary approach calls for avoidance of serious or irreversible damage, by choosing options that have the lowest probability of long-term risk when uncertainty is high. Although decisions based on a precautionary approach are founded on scientific estimates of probability, they include economic and social factors and incentives for minimizing environmental damage. The precautionary approach has not been broadly or enthusiastically endorsed by policy makers or managers in the United States. With respect to fisheries, U.SI agencies' policies post-poned regulatory action to reduce overfishing until the evidence for stock declines proved overwhelm-ing. This was evident in debates on the northwest Atlantic groundfish fishery. The results were disas-trous. In contrast, early adoption of the precaution-ary approach would have incorporated the best sci-ence available. This might have included a call for lowering levels of total allowable catch for almost all species., requiring changes in gear and mesh sizes, and mandating the adoption of other alterna-tives to prevent overexploitation of fisheries stock (Myers and Mertz, 1998; Applegate, et al., 1998). Applying the precautionary approach might also have resulted in the shutting down of a fishery for prolonged periods, such as has occurred with cod fishing off Newfoundland, or in setting aside refuges, such as the temporary closures now in effect on Georges Bank (Lauck et al., 1998). Since July 1998, the New England Fisheries Management Council (NEFMC) has adopted some of these more restrictive policies, but for several species the delay in taking action has only added to the length of time needed to reach maximum sus-tainable yield. Another area where a precautionary approach has been touted involves the role of habitat in recovery of fisheries. Proponents of the precaution-ary approach want restrictions on selected gear types and protection of vulnerable habitats (such as hard bottoms in waters deeper than 30 m where recovery of benthic communities takes decades) or in areas where the effects of fishing gear on benth-ic communities are unknown (Witman, 1998; Collie, 1998; Auster and Langton, 1999; Watling, 1998). They recommend categorizing habitats by their vulnerability to trawling and establishing marine protected areas until data are gathered to demonstrate minimal impacts (Collie,. 1998; Auster and Langton, 1999). This is not a new concept: Our present information indicates that it is notfishing with the otter trawl but overtishing which is to be guarded against... the restriction of the use of the otter trawl to certain definite banks and grounds appears to be the most reason-able, just and feasible method ofregula-tion which has presented itself to us. -Alexander et al., 1914 Others would claim that many areas have been fished for years and that habitat alteration by fish-ing gear is comparable to storms and natural envi-ronmental events (Mirarchi, 1998; Pendleton, 1998). There is concern by the fishing community that no amount of data will be sufficient to permit fishing and use of all fishing gear types. The fish-erman's concern represents the basic differences between the precautionary principle that restricts all use and the precautionary approach that recom-mends caution until evidence is collected showing there is minimal impact. The distinction is worth repeating. Proponents of the precautionary principle would ban all trawling because it negatively impacts habitat. Proponents of the precautionary approach would restrict trawling in vulnerable areas until data were gathered to demonstrate a management approach to minimize damage. MANAGING FiSHERIES USING AN ECOSYSTEM APPROACH Although fisheries have traditionally been managed individually, an ecosystem approach to fisheries management is receiving increasing sup-port. However, there are many definitions of an ecosystem approach and therefore many different expectations of what its application can achieve in fisheries management. For example, the SFA pro-rmoted an ecosystem approach, by requiring each
168 I'LiFRSON & KOBINS;ON management council to include both demarcation and protection of essential fish habitat in their fish-eries management plans by October 1998 (Kurland, 1998). Even though the SFA continued to focus on a single species approach, the new provisions of the Act encourage research on life his-tory, biological interactions, and the environmental variables that define habitat (physical, geochemi-cal, and biological components). However, fish habitat is covered in the same large grid size as used by the National Marine Fisheries Service (NMFS) for fish stock assessment (approximately 700 km2 in the northwestern Atlantic). Information on presence and/or absence and available life histo-ry data are assembled for each species managed for each grid area (NEFMC 1998). Fishers have knowledge on a smaller scale, but it is difficult to integrate their data into habitat studies (Pederson and Hall-Arber, 1999; Hall-Arber and Pederson, 1999). For many species, growth, reproduction and productivity data are lacking. Unless new resources or current research funds are reallocated, fisheries data collection and research will continue to sup-port current studies that are not focused on habitat and the relationship of habitat to productivity. The recognition that habitat protection is critical for the development of sustainable fisheries is a major step along the path to ecosystem-based fisheries man-agement (Langton et al., 1995, 1996; Steneck et al., 1997; Deegan and Buchsbaum, Chapter 5). DEVELOPING NEW MODELS The current approach to fisheries management uses various stock assessment models that input quantitative population data from fisheries inde-pendent surveys, landings data, and the scientific literature to predict future stock abundance (NEFSC, 1998). These models use previous years' data on yield, growth, recruitment and mortality to predict rates of productivity and biomass. The degree to which stocks are exploited, and the exis-tence of growth or recruitment overfishing can be assessed from a model's output. The predictions from stock assessment models are used to recom-mend levels of fishing in the future. While applica-ble to the overfishing question, these models are not designed to incorporate impacts caused by changes in critical habitat and contaminant effects on susceptible life stages. The National Research Council (NRC, 1998) recently reviewed five major stock assessment models and approaches used by NMFS and fishery managers nationwide. They compared the out-comes of each model using five actual or simulated datasets, covering a 30-year period. None of the models were entirely satisfactory in predicting stock abundance and most overestimated the ensu-ing year's biomass by more than 25%. In addition, the models exhibited a multi-year lag time in detecting trends (overestimating biomass during a simulated decline, and underestimating biomass during a simulated increase in abundance). The current stock assessment models upon which recent New England groundfish manage-ment has been based, were criticized by NRC for not realistically accounting for natural population variability or environmental fluctuations, and for being focused on single species in a multispecies ecosystem (NRC, 1998). In addition, they ignore interspecies interactions (predator-prey, competition for space.and food), and make no attempt to overlay stochastic environmental variations (seasonal varia-tions as well as episodic events) or long-term envi-ronmental trends on their deterministic algorithms. Natural environmental fluctuations can lead to enormous changes in year class strength in some fisheries (greater in short-lived or r-selected species than long-lived or K-selected species) and are difficult to assess and incorporate into models (Sutcliffe, 1973; Hofinann and Powell, 1998). Despite its critique of the models, the NRC report (.1998) did not recommend abandoning cur-rent approaches using single species assessment models and did not really propose an alternative. It did encourage continued research in model devel-opment. In the short term, single species assess-ment models will probably provide the most useful data for fisheries management. However, other models, which incorporate both environmental fac-tors and multi-species interactions should be vigor-ously pursued and added to the current methods of stock evaluation. These models should include the effects of contamination, fishing mortality and habitat issues, plus stochastic factors to account for temporal environmental variability (Hofmann and Powell, 1998). Since these newer models incorpo-rate the existing single-species assessment models, continued refinement of single-species models can actually be viewed as a step along the way to more
\\IANA(~iFNIILNI IMPUL Al XI[ONS 169 ecosystem-based models. Attempts to integrate physical and chemical parameters with biological data are still few in number. One local example is the three-dimension-al Massachusetts Bay model that has been eight years or more in development and is used in assessing the effects of an outfall in Massachusetts Bay (HydroQual, 2000). It combines a hydrody-namic model, based on physical parameters with chemical and biological data (nutrients and phyto-plankton response) to forecast plankton productivity. It is considered a successful, chemical-biologically coupled model, yet it fails to identify peaks of spring and fall blooms, uses general values for pre-dation by zooplankton and the benthos, and ignores large species, such as fish and marine mammals (HydroQual, 2000). Another physical-biological model is one developed to hindcast the likely source of lobster larvae that settled in mid-coast Maine (Incze and Naimie, 2000). These investigators predict that lar-vae come from a broad section of the upstream coast (both inshore and offshore) of Maine and suggest a link between offshore reproduction and inshore recruitment. Both the MWRA (2000) and the lncze and Namie (2000) models provide infor-mation that can supplement current stock assess-ments and provide managers with additional and relevant information. Research efforts, mostly from the emerging fields of ecotoxicology and environmental risk assessment, are resulting in better, more compre-hensive fisheries models. Waller et al. (1971) and Wallis (1975) first proposed to include contaminant effects into fisheries-derived population models to predict population effects. Similarly, a number of studies incorporated contaminant data into simple ecological models (Daniels & Allen, 1981; Gentile et al., 1983). Summers and Rose (1987), analyzing time series data, were able to differentiate overfish-ing from hydrographic variability and contaminant effects in striped bass (A1 saxatilis) and American shad (A. sapidissima) populations in the Potomac, Delaware and Hudson Rivers. They pointed out that few previous studies have successfully attempted to examine complex environmental vari-ables and, of those that had, most simply correlated stock size with environmental parameters using an arbitrary time lag. Barnthouse et al. (1987) have proposed a risk-based method to apply toxicity test data to fish population models, although they warn against using their model to predict long-term pop-ulation impacts. These authors recognized the simi-larities in such problems as identifying the cause of power plant fish kills, projecting optimal fishing effort, and determining the impact of environmen-tal chemicals on fish populations. They were able to use this reproductive potential fisheries model, combined with chronic toxicity findings, to assess the effects of five chemicals (4 pesticides and methyl mercury) in Chesapeake Bay striped bass populations (Barnthouse et al., 1989). These toxi-cants not only affected survival, but also had a sig-nificant impact on fecundity. In a subsequent study, Barnthouse et al. (1990) demonstrated that contam-inants had a relatively greater impact on overfished populations of striped bass and menhaden than on populations not stressed by overexploitation. Life history models have also been developed for bivalves and for assessing the sensitivity of life history stages to environmental changes (Weinberg et al., 1997; Caswell, 1996). Thus, a number of studies have demonstrated that fisheries models can be integrated with chemni-cal, physical and toxicological data. Incorporating these models into fisheries management decisions, at least as complementary approaches to the cur-rent single species models are a good first step. The next step in the development of holistic approaches is the incorporation of habitat impacts, e.g., predator-prey relationships, trophic-level interactions, and environmental factors into models used by fisheries managers. Development of these models is one of most pressing needs for fisheries management and should provide information for addressing those supporting a precautionary approach. The shift from our current single-species man-agement to an entirely ecosystem-based approach is a millennium jump. Because of the inherent complexity involved (both physical and biological), our current data analysis and modeling algorithms are not sufficiently developed to allow us to take an ecosystem-based approach at the present time. More holistic approaches, using a suite of ecosys-tem-based models are clearly needed, to augment stock assessment models, if not to replace them. Models of course are only as good as the data that they use. One of the most productive uses of modeling is to point out critical data gaps and the
170 PEIWRSON & RO)BIN\\SON need for additional monitoring. In addition, models can be used to set priorities for new data develop-ment, ruling out the collection of data on parame-ters that have little effect on the critical ecosystem relationships. The contributors to this volume have identified a variety of data gaps/research needs (Table 10.2), all of which should be incorporated into the holistic approaches and ecosystem-based models that are recommended. For example, long-term monitoring data (multi-decadal) are absolutely vital to all efforts to test ald verify newly devel-oped models. While these data are available for offshore groundfish, stock assessment data are scant for inshore bivalve populations. Contaminant effects on aquatic populations are also relatively rare, although they are currently receiving much needed attention by the field of ecotoxicology. Regional and state fisheries management agen-cies are likely to resist adopting these more com-plicated, holistic approaches in their present state of development. Nevertheless, these are powerful analytical tools that can be used to better under-stand the interactions among a variety of anthro-pogenic impacts on fish stocks and to explore the impacts that various management options will have on these stocks. These models will continue to be refined as more data are collected and as more fisheries managers and biologists become familiar with not only the power, but the limitations of these models. Fisheries management can facilitate adoption of new approaches by supporting research into model development, testing their robustness and usefulness as applied to fisheries issues and adopting those models that are cost-effective. The opportunity exists for innovative approaches that will invigorate fisheries management. ADAPTIVE MANAGEMENT Adaptive management is a scientific approach that decision-makers can use for a variety of environmental problems (Costanza et al., 1998). It is a process whereby managers repeatedly modify their management decisions based on targeted col-lection of new data and reassessment of the situa-tion. It is akin to scientists stating a hypothesis, and then collecting data that either refutes or supports the hypothesis. Based on the results of initial experiments, scientists may modify the initial hypothesis, and then devise additional experiments to address the new hypothesis. The scientific pro-cess is a continuous one. However, managers are usually constrained by regulations and a vague sense of how to incorporate scientific data into management decisions. Adaptive management is a particularly useful technique for managing when uncertainty is high. The recent round of assessments, limiting days at sea, stock reassessments, and area closures in the Georges Bank groundfish fishery by the New England Fishery Management Council is an adap-tive management strategy. When it Was obvious that stocks could not be restored first by increasing mesh size and then by limiting the number of days at sea and catch quotas (NEFMC, 1994a), more drastic measures were implemented (NEFMC, 1994b, 1996). Areas throughout the Gulf of Maine were closed to fishing. Depending on the results of new stock assessments, additional closures and restrictions are contemplated. Recent results indi-cate that total biomass of cod has increased in the closed areas, but that it is too early to see an increase in either the number of juvenile cod or in recruitment (NEFSC, 1998, but see also Murawski, Chapter 2 this volume). It is predicted that rebuild-ing Georges Bank groundfish stocks will take many years (Murawski, Chapter 2; Myers et al., 1995). Fisheries managers revise their management decisions repeatedly, as new data are available. This adaptive approach needs to be applied to other fisheries. A suite of management options, (e.g., days at sea, total allowable catch, closed areas, mesh size, gear modifications, limited entry, quota systems), offer managers tools for employing adap-tive management approaches, but not all are avail-able to New England managers (e.g., individual take quotas or ITQs that have been successful in selected fisheries). To learn from management decisions, each option should be scientifically ana-lyzed to evaluate its effectiveness. Socio-economic data that link management decisions to long-term sustainability and conversely over-exploitation to long-term impacts on fishing communities are scarce (Hall-Arber, Massachusetts Institute of Technology, Cambridge, MA, pers. comm.) Adaptive management is not effective without a mechanism for gathering new data. Similarly, unpopular restrictions are difficult to enforce with-out first gaining the confidence of the fishing community that such restrictions are based on good
MNA..6.(E\\IENU INII'LICAAl[ONS 171 information and can be modified as additional information becomes available. As an example, under the SFA, fishery managemnent plans (FMPs) had to be modified by October 1998 to include identification and protection of essential fish habitat. Habitat data were extremely uneven and spotty. For New England groundfish, there were some rel-ative abundance data for several life stages (eggs to adults), but there was a paucity of information on spawning adults and other detailed life history data. Management decisions still needed to be made, regardless of the detail and extent of the data on each species. When only presence/absence data were available, fishery councils, applied a pre-cautionary approach and generally designated a larger area of habitat as essential to fish than they might have if more precise habitat information were accessible. Adaptive management provides the framework to routinely review the size of essential fish habitat, as more habitat and life history data become available. The adaptive management approach could eas-ily be applied to a broader spectrum of fishery issues (Table 10.2). For example, temporary closed areas are being used to help build up groundfish stocks, and the possible need for permanent refuges is being discussed. Because this is a rela-tively new approach, many questions are raised. Do refuges where no fishing is allowed lead to increased spawning biomass both within and out-side the refuge? Is there an optimal size, number, and distance for protected areas to provide safe refuge? When are seasonal or permanent closures appropriate? How should refuges be managed? Fisheries scientists in collaboration with marine ecologists can conduct the necessary studies to fill in the data gaps. Using adaptive management, the results of this ongoing research and monitoring could be incorporated into management review and management decisions modified accordingly. DATA NEEDS One recommendation deserves to be highlighted again - the need for more current data on each commercially important species (e.g., population, recruitment, habitat) and on the various impacts on these species (e.g., predation, competition, habitat alteration, contamni-nation, climate, seasonal weather pat-terns, episodic events). This need has been emphasized repeatedly over the years: All of the participating agencies agreed that the number one priority in any effort to protect/restore the environ-mental integrity of our coastal waters is the development and implementation 0/f a research and monitoring program. -MA MRCC (Marine Resources Coordinating Committee), 1987 The relative impact of fishing, contami-nants, and estuarine habitat degradation on marine fisheries needs to be evaluat-ed. This complex issue ultimately needs to draw on several data sources, such as the semiannual MDMF [Massachusetts Division of Marine Fisheries] stock assessment and site specific estuarine surveys.... -Buchsbaium et al.. 1991 The absence of adequate data is the pri-mary factor constraining accurate stock assessment. -NRC, 1998 Because the cry for 'more data' has been raised so often, some managers, legislators and the public have grown insensitive to the call and no longer acknowledge it as a vital need. This is unfortunate because there is a genuine need for specific data to answer pragmatic and practical questions raised by fisheries managers. There are several good exam-ples of projects with well-defined goals that have implemented research and monitoring programs to address issues (MWRA, 1991; MBP, 1996). The process identified for developing monitoring pro-grams outlined in Managing Troubled Waters: The Role of Marine Environmental Monitoring (NRC, 1990) should be adapted by fisheries managers in developing observing systems that address data needs. Effective programs evolve from planning and involvement of stakeholders. The process,
1 72 V'IL)IKSON.K, R' fflNSO\\ which is easily adapted to identitying research needs, involves identifying the goals, reviewing what data exist, developing a monitoring strategy, analyzing results andreviewing the information produced with respect to the initial goals. The resource assessment program, established in 1974 in Massachusetts, has a specific goal - sound scientific and statistical input for stock assessment, and is considered a valuable contribu-tion to the National Oceanic and Atmospheric Administration (NOAA) database for groundfish (Howe et al., 1979). To its credit, the program has changed very little since 1979. It provides over 20 years of data using consistent methods with NOAA effort. To its detriment, the program has changed very little since 1979. Lack of resources has limited adding research components or additional monitor-ing activities to any significant degree. In addition to the data used for stock assess-ments, food preference data has been collected by NMFS from 1973 to the present. These data were summarized and synthesized in analyses and mod-els that range from basic descriptions and statisti-cally analyses to predictive and theoretical models (NEFSC 1998). A FINAL WORD What :' gone and what s past help should be past grief -William Shakespeare, 1623, The Winter ' Tale ...you better start swimmin' Or you'll sink like a stone For the times they are a changin'. -Bob Dylan, 1963 Today, there is an extraordinary need for a more scientific management of our fisheries. By recognizing that species do not exist in isolation from other species, and that each species has adapted to its own specific habitat, the need for ecosystem-based management of our fisheries becomes apparent. A similar recommendation for "ecosystem approach" in the management of our world's resources has been made in a recent publi-cation of the World Resources Institute (2000). Single-species management can no longer be relied upon to address the fishing pressure on wild stock. Considering only single stressors (fishing mortality, contaminant toxicity, habitat alteration) limits man-agement options and may lead to erroneous deci-sions that have negative effects on other fisheries. Because pollution has had an impact on some fish (e.g., various anadromous fish; winter flounder (Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus), striped bass (M sax-atilis), mussels (Mytilus edulis), and lobsters (Homarus americanus)) and habitat modifications have affected some species (e.g., anadromous fish and winter flounder), these factors may be having some effect on all of our fish stocks. A variety of well-established ecological tenets must now be incorporated into our management decisions - the finite limitation of marine productivity; the impor-tance of biodiversity for maintenance of ecosystem health and vigor; and the reliance on habitat at crit-ical life history stages. It is time to move towards a more holistic, ecosystem-based paradigm for scien-tific fisheries management. In practical terms, however, the fishing com-munity, including the industry, mainagers, and sci-entists) is not ready to make this paradigm shift. Neither the data nor the tools (conceptual and pre-dictive models) are available which would allow us to manage any ecosystem. Developing these mod-els, even though the parameters involved are numerous and the overall system complex, should be a high priority. In addition to collecting data and refining our existing models, the use of these mod-els will eventually evolve into the holistic tools that we need. Many data needs have been identified (e.g., population and recruitment dynamics, predator-prey and competition relationships, identification of essential habitat for all life history stages, con-taminant impacts on populations, socio-economic effects on fishing communities). In general, the majority of these parameters are neglected because of the complexity involved and our inability to manage complexity. Applying a precautionary approach to actions that may have adverse effects is a management option that offers the opportunity to incorporate scientific information and new data. Pilot projects and adaptive management approaches
NIANAGHiMIENI' I M LICA-1tONS 1 73 should be used to evaluate an action before it is adopted on a broad scale. Investing in obtaining data that supports holistic approaches to managing fisheries within an ecosystem framework-will pro-vide a basis for an integrative strategy toward man-aging all species. Our observation is that fisheries managers have not effectively used new sources of information (e.g., research and monitoring data from the National Estuarine Program, Sea Grant College Programs, US Geological Survey, and Massachusetts Water Resources Authority). This occurs, in part, because fisheries models are cur-rently population based and the data have not been distributed effectively. Although not discussed explicitly, the need for improved data management and distribution remains key to successful integra-tion of research data and models into management decisions. Scientifically-based fisheries management can only be achieved through multidisciplinary collab-oration. Fisheries managers will need to actively promote discussion and exchange among practi-tioners from a variety of disciplines (e.g., fisheries science, marine ecology, aquatic toxicology, sociol-ogy). In addition, fishermen's knowledge is now being actively solicited and is recognized as an important source of data that had previously been ignored. Scientific insights into ecosystem dynam-ics and management constraints are less than ideal, but with a long-term research plan, information can be gathered to improve ecosystem-level under-standing. The vision for the future is the integration of information from all sources, the development of holistic models that realistically represent ecosystems, and the wise use of knowledge for improved management decisions. With committed individuals in the planning process, the goal of sus-tainable fisheries in New England waters for the next generation is at hand. Are we up to the challenge? LITERATURE CITED Alexander, A. B. 1914. Otter-trawl Fishery. pp. 1-97. In: Report of the U.S. Commnissioner of Fisheries, Appendix VI. Applegate, A., S. Cadrin, J. Hoenig, C. Moore, S. Murawski, and E. Pikitsch. 1998. Evaluation of Existing Overfishing Definitions and Recommendations for New Overfishing Definitions to Comply with the Sustainable Fisheries Act. Final Report of the Overfishing Definition Review Panel, June 17, 1998, U.S. Dept. of Commerce. NMFS. Auster. 1'..J. and R. W. Langton. 1999. The effects of fishing on fish habitat. pp. 150-187 In: Benaka. l..R. (ed.) Fish Habitat: Essential Fish tlabitat and Rehabilitation. Am. Fish. Soc. Symp.
- 22. Bethesda. MD.
Barnthouse, L.W., G.W. SLter II, A.E. Rosen and J.J. Beauchamp. 1987. Estimating responses of fish populations to toxic contami-nants. Environ. Toxicol. Chem. 6: 811-824. Barnthouse, L.W., G.W. Suter 11 and A.E. Rosen. 1989. Inferring pop-ulation-level significance from individual-level effects: An extrapolation from fisheries science to ecotoxicology. In: Aquatic Toxicology and Environmental Fate. I Ith Vol. STP 1007, M. Lewis and G.W. Suter 11, eds. American Society for Testing and Materials. Philidclphia, PA pp. 289-300. BarnthousC, L.W., G.W. Suter 11 and A.E. Rosen. 1990. Risks of toxic contaminants to exploited fish populations: Influence of life his-tory, data uncertainty and exploitation intensity. Environ, Toxicol. Chem. 9: 297-311. Bewers, J.M. 1995. The declining influence of science on marine environmental policy. Chem. Ecol. 10: 9-23. Buchsbaum, R.. N. Maciolek, A. McElroy, W. Robinson and J. Schwartz. 1991 1. Report of the I..ving Resources Committee of the Technical Advisory Group for Marine Issues. Report to the Secretary of Environmental Affairs, Massachusetts Executive Office of Environmental Affairs, Boston, MA. I5 pp. Casey, J.M. and R.A. Myers. 1998. Near extinction of a large, widely distributed fish. Science 281: 690-692. Caswell, H. 1989. Analysis of life table response experiments I. decomposition of effects on population growth rate. Ecological Modelling 46:221-237. Collie..I 1998. Studies in New England of fishing gear impacts on the sea floor. pp. 53-62. In: Dorsey, E and J. Pederson (eds.) Efflects of Fishing Gear on the Sea Floor of New England. Conservation Law Foundation, Boston, MA. Costanza, R., FAndrade, 1. Antunes, M. van den Belt, D. Boersma, D.F. Boesch, F. Catarino, S. Hanna, K. Limburg, B. Low, M. Molitor, J. G. Pereira, S. Rayner, R. Santos, J. Wilson and M. Young. 1998. Principles for sustainable governance of the oceans. Science 281: 198-199. Deegan. L. and R. Buchsbaum. This volume. Chapter 5. Daniels, R.E. and J.D.Allen. 1981. Life table evaluation of chronic exposure to a pesticide. Can. J, Fish. Aquat. Sci. 38:485-494. Dorsey, E.M. and J. Pederson (eds.). 1998. Effects of Fishing Gear on the Sea Floor of New England. Conservation Law Foundation, Boston, MA. 160 pp. FAO (UN Food and Agricultural Organization). 1994.;The Precautionary Approach to Fisheries with Reference to Straddling Fish Stocks and Highly Migratory Fish Stocks. FAO publication A/Conf 164/INF/8, 26 January 1994.25 pp. FAO (UN Food and Agricultural Organization). 1997. Review of the State of the World Fishery Resources: Marine Fisheries. FAO Fisheries Circular No. 920 FIRM/C920 (ISSN 0429-9329). Fisheries Dept, FAO, Rome, Italy. Gentile J.H., S.M. Gentile and G. Hoffman. 1983. The effects of chronic mercury exposure on survival, reproduction, and popula-tion dynamics of A'Iysidopsis bahia. Environ, Toxicol, Chem. 2: 61-68. Hall-Arber, M. and J. Pederson. 1999. Habitat observed from the decks of fishing vessels. Fisheries 26(6):6-13 Hofmann, E.E. and T.M. Powell. 1998. Environmental variability effects on marine fisheries: Four case histories. Ecol App2. 8 (Supplement): S23-S32. Holt, S.J. 1969. The food resources of the ocean. Sci. Amer. 221: 178-194. Howe, A.B., D.B. Maclsaac, B.T. Estrella, F. J. Germano. 1979. Massachusetts-Coastwide Fishery Resource Assessment. MA Division of Marine Fisheries, Boston, MA. HydroQual. 2000. Bays Eutrophication Model (BEM): modeling analysis for the period 1992-1994. Boston: Massachusetts Water
174 'EiiERSiiN & KRI iiNSO.' Resources Authority. Report ENQIJUAD 2000-02. 158 p. Incze. L.S. and CE. Naimie. 2000. Modeling the transport of lobster (Homarus anmericanus) larvae and postlarvae in the Gulf of Maine. Fish. Oceanoor. 9:99-113. Kurland, J.M. 1998. Implications of the essential fish habitat provi-sions of the Magnuson-Stevens Act. In: Effects of Fishing Gear on the Sea Floor of New England. E.M. Dorsey and J. Pederson (eds.). Conservation Law Foundation, Boston, MA. Pp. 104-106. Langton, R.W., PJ. Auster and D.C. Schneider. 1995. A spatial and temporal persepctive on research and management of groundfish in the northwest Atlantic. Rev. Fish. Sci. 3: 201-229. Langton, R.W., R.S. Steneck, V. Gotceitas, F. Juanes and P. Lawton. 1996. The interface bet\\\\wcn fisheries research and habitat mail-agement. N. Atn. J. Fish. Manatte. 16: 1-7. Lauck, T., C.W. Clark, M. Mangel and G.R. Munro. 1998. Implementing the Precautionary Principle in fisheries manage-ment through marine reserves. Ecol. ArnI. 8 (Supplement): S72- $78. MA DMF (Division of Marine Fisheries). 1985. Assessment at Mid-Decade: Economic, Envirionmental, and Management Problems Facing Massachusetts Commercial and Recreational Marine Fisheries. Massachusetts Division of Marine Fisheries, Boston, MA. MDMF PubI. # 14224-65-500-10-85-C.R. 31 pp. MA MRCC (Marine Resources Coordinating Committee). 1987. Action Plan of the Marine Resources Coordinating Committee to Address Marine Fisheries and Water Quality Problems in Massachusetts. Executive Summary. MRCC, Boston, MA. 9 pp. Mann, K. 1-1. 1982. Ecology of"Coastal Waters: A Systems Approach. Blackwell Scientific Puib., Boston, MA. 322 pp. Mann, K. H. and J.. R. N. Lazier. 190 1. Dynamics otv Marine Ecosystems: Biological-Physical Interactions in the Oceans. Blackwell Scientific 'ubl., Boston, MA. Pp. 466. MBP (Massachusetts Bays Program) 1996. Massachusetts 13 avs 1996 Comprehensive Conservation & Management Plan: An Evolving Plan lor Action. Boston, MA. Mirarchi, F. 1998. Bottom trawling on soft substrates. pp. 80-84 Ir: Dorsey, E. and J. Pederson (eds.) Effects of Fishing Gear on the Sea Floor of New England. Conscrvation Law Foundation, Boston, MA. Murawski, S. Chapter 2. This volume. MWRA (Massachusetts Water Resources Authority) 199 1. Efll uent Outfall Monitoring Plan [hase 1: Baseline Studies. MWRA Environmental Quality Department Misc. Report No. Ms-2. Boston, MA. 95pp. Myers, R.A., N.J. Barrowman, J.A. Hutchings and A.A. Rosenberg. 1995. Population dynamics of exploited fish stocks al low popu-lation levels. Science 269: 1106-1108. Myers, R.A. and G. Mertz. 1998. The limits of exploitation: A precau-tionary approach. Eol.Appl. 8 (Supplement): S 165-S 169. NEFMC (New England Fishery Management Council). 1994a1 Northeast Multispecies Fishery Management Plan. Amendment
- 5. 50 CFR Part 651. Implemented I March 1994.
NEFMC (New England Fishery Management Council). 1994b. Northeast Multispecies Fishery Management Plan. Amendment
- 6. 50 CFR Part 651. Implemented 30 June 1994.
NEFMC (New England Fishery Management Council). 1996. Northeast Multispecies Fishery Management Plan. Amendment
- 7. 50 CFR Part 651. Inplemented I July 1996.
NEFMC (New England Fishery Management Council). 1998. Final Amendment #11 to the Northeast Multispecies Fishery Management Plan, Amendment #9 to the Atlantic Sea Scallop Fishery Management Plan, Amendment #1 to the Monkfish Fishery Management Plan, Amendment # 1 to the Atlantic Salmon Fishery Management Plan, Components of the Proposed Atlantic Herring Fishery Management Plan for Essential Fish Habitat incorporating the Environmental Assessment, Volume 1. October 7, 1998. 338 pp. NEFSC (Northeast Fisheries Science Center). 1998. Report of the 27th Northeast Regional Stock Assessment Workshop (27th SAW) Stock Assessment Review Committee (SARC) Consensus of Summary of Assessments. Northeast Fisheries Science Center Ref Doc. 98-03. National Marine Fisheries Service, Woods Hole, MA. NOAA (National Oceanographic and Atmospheric Administration). 1998. Status of the Fishery Resources off the Northeastern United States for 1997. NOAA Technical Memorandum NMFS-NE-108. National Marine Fisheries Service, Woods Hole, MA. NRC (National Research Council). 1990. Managing Troubled Waters: The Role of Marine Environmental Monitoring. NRC POD469. 136 pp NRC (National Research Council). 1998. Improving Fish Stock Assessments. National Academy Press, Washington D.C. 188 pp. NRC (National Research Council).. 1999. Sustaining. Marine Fisheries. National Academy Press, Washington D.C. 164 pp. Pauly, D., V. Christensen, J. Dalsgaard, R. Froese and F. Torres, Jr. 1998. Fishing down marine food webs. Science 279: 860-863. Pendleton, C. 1998. "The Edge of the Bottorn"-heavily trawled and consistently productive. pp. 138-139 In: Dorsey, E. and J. Pederson (eds.) Effects of Fishing Gear on the Sea Floor of New England. Conservation Law Foundation, Boston, MA. Pederson, J. and M. Hall-Arber. 1999. Fish habitat: a focus on New England fishermen's perspectives, pp. 188-2 11. In: Benaka, L.R. (ed.) Fish Habitat: Essential Fish Habitat and Rehabilitation. American Fisheries Society Symposium 22, Bethesda, MD. Russell-Hunter, W. D. 1970. Aquatic Productivity. Macmillan Publ., N.Y. 306 pp. Ryther, J.H. 1969. Photosynthesis and fish production in the sea. Science 166: 72-76. Steneck, R.S., R.W. Langton, F. Juanes, V. Gotceitas and 1. Lawton. 1997. Response: The interface between fisheries research and habitat management. N. Am. J. Fish Manage. 17: 596-598. Summers, J.K. and K. A. Rose. 1987. The role of interactions among environmental conditions in controlling historical fisheries vari-ability. Estuaries 10: 255-266. Sutcliffe, W I1. 1973. Correlations between seasonal river discharge and local landings of the American lobster (Honoar-is aniericanus) and Atlantic halibut (Hlippoglossus hippoglossrts) in the Gulf of St. Lawrence. J. Fish Res. Bd. Can. 30:856-859. VanderZwaag, D. 1994. CEIPA and the Precautionary Principle/Approach. Canadian Ministery of Supply and Services, ISBN 0-662-61202-7. 32 pp. Waller, W.T., ML. Dahlberg, R.E. Sparks and J. Cairns, Jr. 1971. A computer simulation of the effects of superimposed mortality due to pollutants on populations of fathead minnows (Pimnephales promelas). J. Fish. Res. Bd. Canada 28: 1107-1112. Wallis, I.G. 1975. Modeling the impact of waste on a stable fish pop-ulation. Wat. Res. 9: 1025-1036. Watling, L. 1998. Benthic fauna of soft substrates in the Gulf of Maine. pp. 20-29 In: Dorsey, E. and J. Pederson (eds.) Effects of Fishing Gear on the Sea Floor of New England. Conservation Law Foundation, Boston, MA. Weinberg, J.R., D. F. Leavitt, B. A. Lancaster, and J. McDowell Capuzzo. 1997. Experimental field studies with Mya arenaria (Bivalvia) on the induction and effect of hematopoictic neoplasia. J. of Invert. Pathol. 69:183-194. Weber, P. 1994. Safeguarding Oceans. pp. 41-59 In: State of the World 1994. A Worldwatch Institute Report on Progress Toward a Sustainable Society. W.W. Norton, New York. 265 pp. Williams, J.D and R. M. Nowak. 1986. Vanishing species in our own backyard: Extinct fish and wildlife of the United States and Canada. In: The Last Extinction. L. Kaufrnan and K. Mallory (eds.). The MIT Press, Cambridge, MA. Pp. 107-139. Witman, J.D. 1998. Natural disturbance and colonization on subtidal hard substrates in the Gulf of Maine. pp. 30-37 In: Dorsey, E.
XMAGEM TNI IMPLICATIONS 175 and 1. P'cdcrson (cds.) E'l'ects oi Fishing Gear on the Sea Floor of New England. Conservation Law Foundation, Boston. MA. World Resources Institute. 2000. A Guide to World Resources: 2000-2001. People and Ecosystems. The Fraying Web of Lille. World R*esourcs Institute, Washington, DC.
I I / t 3 iI A 4 j / N I I P~ N <1/4 1/2 ~ 'Ž4 IN 3< 'I}}