ML061420174

Marine Ecology Studies Related to Operation of PNPS, Report 65 Report Period: January 2004 - December 2004, Issued April 30, 2005

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ALICIA WILLIAMSON 301-415-1878
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6 MARINE ECO LOGY STU DIES 6 PILGRIM NUCLEAR POWER STATION REPORT No. 65 Report Period: January 2004 - December 2004 Date of Issue: April 30, 2005 Compiled and Reviewed by:

Environmental Protection Group Entergy Nuclear - Pilgrim Station Plymouth, Massachusetts 02360

TABLE OF CONTENTS SECTION

1. INTRODUCTION

2.

SUMMARY

3. MARINE BIOTA STUDIES 3.1 Marine Fisheries Monitoring Winter Flounder Area-Swept Estimate: Western Cape Cod Bay 2004

[Marine Research, Inc.]

3.2 Entrainment Monitoring Ichthyoplankton Entrainment Monitoring at Pilgrim Nuclear Power Station; January - December 2004 [Marine Research, Inc.]

3.3 Impinaement Monitoring Impingement of Organisms on the Intake Screens at Pilgrim Nuclear Power Station; January - December 2004 [Marine Research, Inc.]

3.4 Hatchery Release & Collection Study Hatchery Production Study, Young-of-the-Year Winter Flounder, Post-Release Collections 2000-2004 [Marine Research, Inc.]

3.5 Larval Transport Study Study of Winter Flounder Larval Transport inCoastal Cape Cod Bay and Entrainment at Pilgrim Nuclear Power Station-February 2005 [Marine Research, Inc.]

Pilgrim Station I Entergy Nuclear

MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 1 Introduction ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

INTRODUCTION A. Scone and Oblective This is the sixty-fifth (65) report, provided semi-annually, on the status and results of environmental surveillance and monitoring programs related to the operation of Pilgrim Nuclear Power Station (PNPS). The monitoring efforts discussed in this report relate specifically to the Western Cape Cod Bay ecosystem with particular emphasis on the Rocky Point area. This report is submitted in accordance with the environmental monitoring and reporting requirements of the PNPS NPDES Permit from the U.S. Environmental Protection Agency (#MA0003557) and Massachusetts Department of Environmental Protection (#359).

The objectives of the Environmental Surveillance and Monitoring Program are to determine whether the' operation of PNPS results in measurable effects on the marine ecology and to evaluate the significance of any observed effects. If an effect of potential significance is detected, corrective steps are taken to address the issue.

The efforts described in this report represent a continuation of monitoring conducted atVPNPS In the past by Entergy (and before that, by Boston Edison Company). This program was submitted to U.S. EPA and MA DEP for review in December 2003 and was subsequently approved. Note that in March 2002, Entergy Nuclear Operations, Inc. became the operator of Pilgrim Station, although Entergy Nuclear Generation Co. is still the owner. This change had virtually no effect on the Marine Environmental Monitoring Programs at PNPS or the personnel associated with them.

B. Marine Blota Studies

1. Marine Fisheries Monitoring Marine Fisheries studies in 2004 focused on winter flounder population parameters to develop an understanding of any PNPS impact on this indicator species. Population estimates and adult equivalency analyses are conducted on this key species to help assess the impact of PNPS entrainment.

Env Mar-Eco(-65 Introduction Entergy Nuclear

Results of the marine fisheries monitoring during the reporting period are presented in Section 3.1. Winter flounder are studied by trawling techniques. L Entergy has conducted efforts to support fisheries enhancement starting in L 2000 and continuing through 2004. Winter flounder were spawned and reared in a hatchery from January to May, and then released near the Plymouth Harbor Yacht Club in mid-May 2004.

Field results have been very favorable. In 2004, 312 tagged fish were U recaptured. Long-term survival experiments (pen studies) were conducted from June to October. The results of these studies are presented in Section 3.4.

2. Entrainment Monitoring -

PNPS has been monitoring entrainment of fish eggs and larvae, and lobster larvae in the plant's cooling water for more than twenty-five years (in 1973-1975 phytoplankton and zooplankton were also studied). Information generated through these studies has been utilized to make periodic modifications in the L sampling program to more efficiently address the question of the effect of entrainment. These modifications have been developed by Marine Research, L Inc. (MRI) in conjunction with Pilgrim environmental personnel, and reviewed and approved by U.S. EPA and MA DEP on the basis of the program results. L Plankton monitoring in 2004 emphasized consideration of ichthyoplankton L entrainment and selected species adult equivalency analyses. The software L program RAMAS Metapop was also used to further explore the potential effects of entrainment on the winter flounder population. Model runs were completed L with fishing mortality and with and without entrainment losses. C Results of the ichthyoplankton entrainment monitoring for 2004 are discussed in Section 3.2. L

3. Impingement Monitoring The PNPS impingement monitoring and survival program identifies, quantifies and determines viability of the organisms carried onto the four intake traveling screens. Results of the impingement monitoring conducted in 2004 by Marine Research, Inc. are discussed in Section 3.3. L Env / Mar-Ecol-65 Introduction Entergy Nuclear .

4. Larval Transport Study In spring 2004, a-modified larval transport study was conducted in coastal Cape Cod Bay. The program was designed to update similar studies conducted in 2000 and 2002, based on the suggestions and comments of federal and state agency reviewers. The results of the 2004 Larval Transport Study are discussed in Section 3.5

5. Benthic Monitoring No benthic monitoring was performed during this period.

C. Station Operation History The annual capacity factor for 2004 was 98.53%, the best annual capacity factor in Pilgrim's history. Monthly average capacity factors (mean electric generation) for 2004 are shown in Figure 1.

In 2004,' there were five (5) minor power reductions associated with thermal backwashes (March 22, June 4, July 30, September 21 and November 16), during which heat-treatment of the intake structure was performed for biofouling control.

The monthly average amount of sea water used for plant cooling water as well as the average discharge water temperatures are given in Figure 2. Discharge flow is shown as percent of total possible flow volume - based on pump run times - from both the circulating water and salt service water systems.

Env / Mar-Ecol-65 Introduction Entergy Nuclear

Electricity Generated - 2004 UoW" Averag 101 100 100 go 100 100 100 I0

.1 0 leo jOt 40 MAY JUN JUL AUG SEP OCT NOV DEC JAN FES MAR APR Figure 1. Monthly Electrical Output from P~igr Station for 2004 (avg. percent capacity factor).

- '-Fbw VoduneI Seawater Discharged -2004 Mwnfthl AverageI 90 100%

so C

tI 70%

701 j60%

a 0 1t I IC

• - 40%

Is APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEM MAR flow).

Figure 2. Seawater Discharged from Pilgrim Station - 2004 (temperature and Introduction Entergy Nuclear Env / Mar-Ecol 65

MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 2 Summary ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

SUMMARY

Results of the January-December 2004 Environmental Surveillance and Monitoring Program at Pilgrim are highlighted below.

Section 3.1 - Marine Fisheries Monitoring:

1. Trawls for winter flounder stock assessment were performed for the tenth consecutive year. The uarea-swept" study consisted of 84 tows in northwestern Cape Cod Bay to estimate this species' population (instantaneous abundance).

2. Winter flounder population size (instantaneous abundance) was estimated using an area/density approach, based on the area-swept densities over the entire study area.

3. Adjusted estimates of winter flounder abundance in the study area for 2004 were 157,532 adults and 247,411 total winter flounder.

Section 3.2 - Entrainment Monitoring:

1. A total of 39 species of fish were represented in the January-December 2004 samples, equal to the 29-year mean.

2. Winter-early spring samples were dominated by Atlantic cod, American plaice eggs along with sand lance, rock gunnel and grubby larvae.

3. Late spring-summer collections, taken from May through July, were dominated by the Labridae-Pleuronectes, Atlantic mackerel, and Paralichthys-Scophthalmus eggs along with radiated shanny, winter flounder, and Labridae-Pleuronectes larvae.

4. Late summer-autumn collections (August-December) were dominated by the Labridae-Pleuronectes, and Paralichthys-Scophthalmus eggs, along with cunner, Atlantic herring, tautog and northern pipefish larvae.

5. Nine (9) lobster larvae were collected in entrainment samples for the January-December 2004 period.

Env / Mar-Ecolu65 Summary Entergy Nuclear

6. Comparisons of ichthyoplankton densities over the 1975-2004 time series suggested that, in most cases, numbers in 2004 were consistent with those L recorded since sampling began at PNPS.

Section 3.3 - Impingement Monitoring:

1. In 638.3 collection hours, a total of 33,591 fish consisting of 35 species were collected off the screens in 2004. L

2. The impingement rate for 2004 was 2.85 fish per hour.

3. Atlantic silverside, Atlantic menhaden, grubby, blueback herring, winter flounder, and rainbow smelt accounted for 39, 31, 7, 6, 6, and 3%, respectively, of the l annual total.

4. From January to December 2004, 20,566 invertebrates representing 12 species U were sampled yielding an impingement rate of 2.63 invertebrates per hour.

Sevenspine bay shrimp (Crangon septemspinosa) were dominant accounting for 78% of the annual total.

Section 3.4 - Hatchery Release & Collection Study L

1. A total of 312 tagged hatchery winter flounder were collected in the beach seine survey in 2004. These fish were collected over 17 sampling events, following release on May 10 and May 11.

2. Fish were successfully maintained in the pens from May 12 until September 2, a total of 114 days.

L

3. The 2004 monthly (84%) and cumulative (80%) survival rates were higher than U the 2003 survival rates. L

4. Assessments from 2000 through 2004 demonstrated that released hatchery fish survival approximates wild fish survival. L L

Env / Mar-Ecol.65 Summary Entergy Nuclear

Section 3.5 - Larval Transport Study 1 This was the third larval transport study performed in Cape Cod Bay to examine the key conditions (net water flow and density of winter flounder larvae) affecting the entrainment of winter flounder larvae.

2. The results of the 2004 study are similar to those of the previous studies performed in 2000 and 2002.

3. There is a consistent net flow of water and winter flounder larvae to the south along coastal Cape Cod Bay in the vicinity of Pilgrim Station.

4. Less than 0.1 % of the net volumetric flow of water in Cape Cod Bay passes through Pilgrim Station.

5. The amount of winter flounder larvae in northwestern Cape Cod Bay that is entrained by Pilgrim Station is conservatively estimated at less than 1% of the net larval transport.

Env / Mar-Ecol-65 Summary Entergy Nuclear

MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 3.1 Marine Fisheries Monitoring

-ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

WINTER FLOUNDER AREA-SWEPT ESTIMATE WESTERN CAPE COD BAY 2004 Submitted to Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station Plymouth, Massachusetts by Marine Research, Inc.

Falmouth, Massachusetts October 20, 2004 Marine Research Inc.

Introduction Field studies around Pilgrim Nuclear Power Station (PNPS) have demonstrated the water withdrawal aspects of plant operations, i.e., entrainment of fish eggs and larvae, and impingement of adult and juvenile fish. The environs around PNPS serve as spawning, nursery, and feeding grounds for winter flounder (Pseudopleuronectes amencanus) and this species is valuable both commercially and recreationally. From 1995 through 1999 the Massachusetts Division of Marine Fisheries estimated the size of the winter flounder population in waters off Pilgrim Station. This study has been continued by Marine Research, Inc. (MRI since 2000, the 2004 work being presented here.

Methods and Materials The study area, sampling methodology, and analytical calculations were the same as those used in the Massachusetts Division of Fisheries (MDMF) studies conducted in 1999 and by Marine Research, Inc. (MRI) from 2000 through 2003. Consistent with the past four years, tow duration was 30 minutes and tows less than 20 minutes were not included in calculations. Eight-four tows were planned for 2004. -The sampling area extended from Humarock, Marshfield southeastward to the Mary Ann buoy, Manomet, from nearshore (9.2 m MLW) out to the 36.6 m (MLW) depth contour (Figure 1; Lawton et al. 2000). Since there is spatial variation in winter flounder abundance by depth (Lawton et al. 1995), stratified estimates of abundance were used to improve precision.

The 55-foot FNV Frances Elizabeth was contracted to sample winter flounder using a Yankee otter trawl with 18.3 m sweep and 14.6 m headrope with 15.2 cm stretch mesh body and a -7.6 cm square mesh cod end with a 4.5 cm mesh liner; it was fished with 12.8 m legs and 73.2 m ground cables. The trawl doors were steel measuringl.8 m x 1.2 m and weighing 205 kg each.

Beginning and end latitude and longitude, start and end times, and boat speed were recorded during each tow. Tow tracks were plotted with Nobeltec Visual Navigation Suite. All winter flounder were measured to the nearest centimeter total length (TL), sexed by assessing the reproductive state and maturity. This included checking for the presence of ripe eggs or sperm and for the presence of ctenoid scales on the left (blind) side of the caudal peduncle. Ctenoid scales often occur on mature males.

Prior to being released all fish were examined for tags (MDMF tagging study 1994 to 1998; Lawton et al. 2000).

Winter flounder population size (instantaneous, absolute abundance) was estimated using an area/density approach, based on the area-swept densities over the entire study area. Calculations were completed using the same procedures employed in 1999 by Lawton et al. (2000). Trawl gear efficiency was unknown and assumed to be 50% consistent with previous estimates. Density was determined by dividing the number of winter flounder per tow by the area of bottom covered. Bottom area was based on tow length and tow width. Tow length was taken from the tracks generated by the Nobeltec Marine Research, Inc.

NmiUGI Ml" o NOTUSEFCR KAVwGA1oPftmPo3E 1 VS-1414 a -2

• yCh4 *am Nak: acbwa Figure 1. "Area-Swept" sampling boundary, Northwest Cape Cod Bay.

- 2 Marine Research Inc.

software. Tow width was estimated using the trawl doors' spread on the bottom. Spread was determined by measuring the between-wire width at the blocks and at six feet aft of the blocks and extrapolated to account for the wire out (usually 450 feet) yielding a typical door spread of 175 feet (54 meters). Door spread was used because of the "herding" action caused by the sediment cloud generated by the doors and legs while towing (Somerton 2003, Somerton and Weinberg 2001, Lawton et al. 2000, Ramm and Ziao 1995, Dickson 1993a and Dickson 1993b). Catch per unit area was calculated for each tow. Computed estimates for adult winter flounder (Ž280 mm TL; Witherell and Burnett 1993) and for all sizes pooled were doubled to account for assumed catch efficiency. Density estimates were multiplied by total acreage (2.674 x 108 m2 ) in the study area to calculate absolute abundance.

Results and Discussion In 2004, 7,387 winter flounder were taken in 84 tows completed between April 19 and May 13 yielding a mean catch of 88 fish per tow (catch per unit effort, CPUE). The CPUE for 2004 was lower than the previous four years but greater than 1995, 1996, and 1999 (Figure 2). The lower relative abundance prior to 2000 may be attributed to the use of a different fishing vessel with possibly different catch efficiencies (Figure 3).

Unadjusted estimates of winter flounder abundance in the study area for 2004 were 78,766 adults and 123,706 total winter flounder. These estimates were doubled to account for trawl efficiency (assumed to be 50%c); the adjusted numbers were 157,532 and 247,411, respectively (Table 1). Winter flounder absolute abundance estimates for adults and total winter flounder were below average in 2004 based on the 1995 - 2003 time series, 80% and 65% of their respective means of 328,284 and 615,222.

3 Marine Research, Inc.

L Winter Flounder CPUE Spring 1995 - 2004 L

200 1.

.. L 50 0

5 by 1,

1995 1996 1997 1998 1999 2000 2001 2002

' Year l,=28OTL EAIiFlounder I Fl gure 2. CPUE for winter flounder caught in Western Cape Cod Bay, 1995-2004.

I L

Winter Flounder - Annual Abundance Estimates Spring 1995 - 2004 L

~1000

~800 - - - - - - - - - - - - - -

L L

200-L Li 400 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 L

Year l6lTotal Abundance -_dult Abundance] L Figure 3. Estimated annual abundance of winter flounder in Western Cape Cod Bay, 1995-2004.

Recent estimates of fishing mortality suggest that it is relatively low with an L

estimated exploitation rate of 12% in 2001 and 2002. The Gulf of Maine stock is not 4

l Marine Research, Inc.

L

considered to be in an overfished state and overfishing is not believed to be taking place at the present time (NEFSC 2003). The lower 2004 area swept estimate relative to 2000 and 2002 is likely the result, at least in part, to the natural and fishing induced decline in the strong 1997 and 1998 year classes. A review of the MDMF resource assessment program has shown a steady decline in the northern stock of winter flounder from 2000 to 2003 consistent with trends found in this study. The MDMF defines the northern stock as extending from the New Hampshire border to Cape Cod (Howe et al. 1994).

It is important to note that the assumed trawl efficiency value of 50% almost certainly varies from year to year and was selected to be conservative. It is probably lower than 50% particularly for small fish which would result in higher population estimates than those presented. For example, Kuipers (1975) reported efficiency of 28%

for a beam trawl which is typically more efficient than an otter trawl. Harden-Jones et al.

(1977) cited in Gunderson (1993) used sonar to estimate that 44% of plaice positioned between the trawl doors were captured. Mearns and Allen (1978) reported efficiencies of 10 to 50% for a small otter trawl. Kjelson and Colby reported a range of efficiencies from 9 to 51%, Grosslien and Laurec (1982) efficiencies of 26 to 38%, and Walsh (1992) values that ranged from as low as 5% for small flounder to 75% for adults.

The Coastal Lobster Investigations Project of the Massachusetts Division of Marine Fisheries maintains temperature monitors in the vicinity of Plymouth at three depth strata (40, 60 and 110 feet). These data along with surface water temperature from National Buoy Data Center Station 44013 (Boston Buoy; available at http://www.ndbc.noaa.gov/station.page.php?station=44013) were plotted from April 1 through May 15 for 2000 to 2004 (Figure 4). Included on these plots was the daily catch per tow for each sampling day. Boston Buoy water temperature data for 2004 was plotted along with the 2000 to 2003 mean in Figure 5. These figures show that 2004 was colder than the previous four years. From April 29 to May 3 there was a 2 degree drop in temperature at the 40-foot and 60-foot monitors. Strong winds on May 3 and 4 were probably responsible for the 2 degree C drop in surface temperature that occurred from May 3 to May 5. This reduction in water temperature may have delayed the inshore migration of mature winter flounder.

Length frequency data for 2004 exhibited a bimodal distribution (Figure 6). The majority of fish sampled were age 2 (Witherell and Burnett 1993). The second mode was age 3 and 4 fish. As in previous years, due to the selectivity of the net and the 4.5 mnm cod-end liner, the number of age 2 and younger fish was probably under sampled (Lawton et al. 2000).

Marine Research, Inc.

Water Temperature 2000 Water Temperature 2001 For The Depth Surata in Cape Cod Bay For The Depth Strata in Cape Cod Bay I. . .

'1--1--- -- -- - - -- - - -- _i .---- - - - - - -

---

, ------ L kk~~~~~ f k Water Temperature 2002 Water Temperature 2003 Fohree= Depth Srt in Cape Cod Day Fohree Depth Stata in Cape Cod Day Water Temperature 2004 For Thre Depth Stra= inCap Cod Day CCB40P6tf ffBII CCCBwa& II* UP^W. lZ *

-- - 00.-. -- -. - - -.-.. - -

Figure 4. Mean daily water temperatures (April 1 to May 15) for three depth strata, Boston Buoy surface and daily catch per tow, 200 to 2004.

. ."z. ."

L L

Marine Research, Inc.

Boston Buoy (NBDC Station 44013)

Surface Water Temperature 15 300 10 -- ------

--- - --- ----- -- -- --- - 2-50 7f__200mZ 5 ------- - -,-1------------- 100

• O 0 SArd 10ApI 15Aprd 20Apt 25 Ad 30 AptI May tomay IsMay Dame 1-00o4 -,1000-2003 Mean UFlounderl Figure 5. Boston Buoy 2004 surface water temperature and 2000 to 2003 mean with 2004 daily catch per tow.

Cape Cod Bay Area Swept 2004 Winter Flounder Length Frequency 0.1 n7,387 I.

0 0.08 0.06 0.04

---

Ji-------- -------

..li d 0.02 0

IIIIIIII....

. ... I 0 5 10 15 20 25 ( 30 35 40 45 50 Length (cm)

Figure 6. Length frequency for winter flounder caught in Western Cape Cod Bay, 2004.

7 MarineResearch, Inc.

fLl 1

Table 1. Estimated abundance (stratified by depth) of winter flounder in the study area I (2.674 x108 m2 at MLW) with 95% confidence limits. Snriny 1995-2004.

L 2280 mm TL All Flounder 444,850 437,438 452,261 1996 Flounder 316,986 314,365 319,607

>280mm TL All Flounder 510,306 506,378 :514,235 4 .,

1997 Flounder 313,959 308,896 319,021 2280 mm TL All Flounder 882,889 887,834 887,945 1998 Flounder 264,812 242,779 286,825

>280 mm TL 1999 All Flounder Flounder 588,450 176,271 553,330 172,306 623,570 180,236 L

>280 mm TL All Flounder 367,908 360,826 374,989 L 2000 Flounder 464,176 450,222 478,126

>280 mm TL All Flounder 826,548 807,952 845,144 L

2001 Flounder 2280 mm TL 400,812 330,709 471,109 470,914 648,316 L

All Flounder 559,713 2002 Flounder

2. 280mm TL 476,263 429,430 523,096 L

741,108 725,285 756,932 2003 All Flounder Flounder

>280mmTL 262,604 223,957 301,247 L 2004 All Flounder Flounder 398,528 157,532 387,156 154,555 409,898 160,509 L

>280 mm IL All Flounder 247,411 242,226 252,596 L l

L Marine Research, Inc.

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Literature Cited Dickson, W. 1993a. Estimation of the capture of trawl gear. I: Development of a theoretical model. Fisheries Research, 16:239-253.

Dickson, W. 1993b. Estimation of the capture efficiency of trawl gear. II. Testing a theoretical model. Fisheries Research, 16:255-272.

Grosslien, M.D. and A, Laurec. 1982. Bottom trawl surveys design, operation and analysis. FAO, CECAF/ECAF SERIES 81/22. 25p.

Gunderson, D.R. 1993. Surveys of Fisheries Resources. John Wiley & Sons, Inc. New York. 248 p.

Harden-Jones, F.R., A.R. Margetts, M. Greer Walker, and G.P. Arnold. 1977. The efficiency of the Garnton otter trawl determined by sector-scanning sonar and acoustic transponding tags. Tapp. P.-v. Reun. Cons. Int. Explor. Mer. 170:45-51.

Kjelson M.A. and D.R. Colby, 1978, The evaluation and use of gear efficiencies in the estimation of estuarine fish abundance. Estuarine Research. pp. 416-424.

Kuipers , B. 1975, On the efficiency of a two-meter beam trawl for juvenile plaice. Neth.

J. Sea Res. 9(1):69-85 Lawton, R.P. B.C. Kelly, V.J. Malkoski, and J. Chisholm. 1995. Final Report on Bottom Trawl Survey (1970-1982) and Impact Assessment of the Thermal Discharge from Pilgrim Station on Groundfish. Pilgrim Nuclear Power Station Marine Environmental Monitoring Program Report Series - Number 7. 56 pp.

Lawton, R.P., B.C. Kelly, J. Boardman, and M. Camisa. 2000. Annual Report on assessment and Mitigation of Impact of the Pilgrim Nuclear Power Station on Finfish Populations in Western Cape Cod Bay. Project Report No. 68 (Jan.-Dec.

1999). In: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-annual Report No. 55. Entergy Nuclear Generation Company, Plymouth, MA.

MRI (Marine Research, Inc.). 2001. Ichthyoplankton entrainment monitoring at Pilgrim Nuclear-Power Station January-December 2000. In: Marine Ecology Studies Related to Operation of Pilgrim Station, Semi-annual Report No. 59. Entergy Nuclear Generation Company, Plymouth, MA.

Mearns, A.J. and M.J. Allen. 1978. Use of Small Otter trawl in coastal biological surveys. EPA- 600/3-78-083, 34p Ramm, D. C. and Y. Xiao. 1995. Herding in groundfish and effective pathwidth of trawls. Fisheries Research. 24:243-259.

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Somerton, D. A. 2003. Bridle efficiency of a survey for flatfish: measuring the length of the bridles in contact with the bottom. Fisheries Research, 60: 273-279. (iI Somerton, D. A. and K. L. Weinberg. 2001. The effect of speed through the water on footrope contact of a survey trawl. Fisheries Research. 53:17-24. L' Walsh.SJ. 1992. Size dependent selection at the footgear of a groundfish survey trawl.

North American Journal 'of Fisheries Management, 12:625-633. l Witherell, D.B., and J. Burnett. 1993. Growth and maturation of winter flounder, Pleuronectesamericanus,in Massachusetts. Fishery Bulletin, U.S. 91:816-820. L L"

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MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 3.2 Entrainment Monitoring ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

ICHTHYOPLANKTON ENTRAINMENT MONITORING AT PILGRIM NUCLEAR POWER STATION JANUARY - DECEMBER 2004 Submitted to Entergy Nuclear Generation Company Pilgrim Nuclear Power Station Plymouth, Massachusetts by Marine Research, Inc.

Falmouth, Massachusetts April 2005

U TABLE OF CONTENTS L SECTION PAGE

SUMMARY

1 L INTRODUCTION 3 HI METHODS AND MATERIALS 3 U IV RESULTS AND DISCUSSION A. Ichthyoplankton Entrained - 2004 11 V B. Unusual Entrainment Values 16 C. Multi-year Ichthyoplankton Comparisons 17 l D. Ichthyoplankton Entrainment Effects - Specific 55 E Lobster Larvae Entrained 93 L V LITERATURE CITED 95 APPENDICES A and B (available upon request) L L

L L

L L

L L

L L

LIST OF FIGURES FIGURE PAGE 1 Entrainment sampling station in PNPS discharge canal. 7 2 Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the winter-early summer season. Percent of total and summed monthly means for all species are also shown. 12 3 Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the late spring-early spring season. Percent of total and summed monthly means for all species are also shown. 14 4 Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the late summer-autumn season. Percent of total and summed monthly means for all species are also shown. 15 5 Mean monthly densities per 100 m3 of water in the PNPS discharge canal for the eight numerically dominant egg species and total eggs, 2004 (bold line). Solid lines encompassing shaded area show high and low values over the 1982-2003 period. 33-38 6 Mean monthly densities per 100 m3 of water in the PNPS discharge canal for the thirteen numerically dominant larval species and total larvae, 2004 (bold line). Solid lines encompassing shaded area show high and low values over the 1982-2003 period. 39-46 7 Numbers of equivalent adult winter flounder estimated to have been lost to entrainment at PNPS using two sets of survival rates, 1980-2004. 82 8 Population size estimated by a Ramas model with and without PNPS entrainment, fishing mortality rates, and population size estimated by 82 bottom trawl in western Cape Cod Bay.

9 Numbers of equivalent adult cunner estimated to have been lost to entrainment at PNPS, 1980-2004. 83 10 Numbers of equivalent adult Atlantic mackerel estimated to have been lost to entrainment at PNPS, 1980-2004. 83 11 Numbers of equivalent adult Atlantic menhaden estimated to have been lost to entrainment at PNPS, 1980-2004. 84

LIST OF FIGURES l FIGURE PAGE 12 Numbers of equivalent adult Atlantic herring estimated to have been lost to entrainment at PNPS, 1980-2004. 84 13 Numbers of equivalent adult Atlantic cod estimated to have been lost to entrainment at PNPS, 1980-2004. 85 LIST OF TABLES TABLE PAGE 1 PNPS ichthyoplankton entrainment values for 2004 by species category, and month used to determine unusually high densities. See text for details. 8-10 2 Species of fish eggs (E) and larvae (L) obtained in ichthyoplankton collections from the Pilgrim Nuclear Power Station discharge canal, L

January-December 2004. 47 1 3 Ichthyoplankton densities (number per 100 m3 of water) for each samp-ling occasion during months when notably high densities were recorded, January-December 2004. Densities marked by + were unusually high L based on values in Table 1. Number in parentheses indicates percent of all previous values during that month which were lower. 48-50 C 4 Species of fish eggs (E) and larvae (L) collected in the PNPS discharge canal, 1975-2004. 51-54 l 5 Numbers of larval winter flounder entrained at PNPS annually by stage, 1980-2004. Number and weight of equivalent age 3 adults calculated by two methods is also shown. Estimates based on full-load flow except where indicated. 86 L

6 Numbers of winter flounder eggs and larvae impinged at PNPS annually, L 1980-2004. Numbers and weight of equivalent age 3 adults calculated by two methods is also shown. 87 L 7 Numbers of cunner eggs and larvae entrained at PNPS annually, 1980-2004. Numbers of equivalent adults are also shown. Estimates based on full-load flow except where indicated. 88 L

• L

LIST OF TABLES (continued)

TABLE PAGE 8 Numbers of Atlantic mackerel eggs and larvae entrained at PNPS annually, 1980-2004. Numbers of equivalent age 1 and age 3 fish are also shown.

Estimates based on full-load flow. 89 9 Numbers of Atlantic menhaden eggs and larvae entrained at PNPS annually, 1980-2004. Numbers of equivalent age 1 and age 3 fish are also shown.

Estimates based on full-load flow. 90 10 Numbers of Atlantic herring larvae entrained at PNPS annually, 1980-2004.

Numbers of equivalent age 1 and age 3 fish are also shown. 91 11 Numbers of Atlantic cod eggs and larvae entrained at PNPS annually, 1980-2004. Numbers of equivalent age 1 and age 3 fish are also shown. 92 LIST OF APPENDICES APPENDIX A* Densities of fish eggs and larvae per 100 &3 of water recorded in the PNPS discharge canal by species, date, and replicate, January-December 2004.

B* Geometric mean monthly densities and 95% confidence limits per 100 m3 of water for the dominant species of fish eggs and larvae entrained at PNPS, January-December 1981-2004.

• Available upon request.

SECTION I

SUMMARY

Sampling of entrained ichthyoplankton at PNPS in 2004 followed the revised protocol initiated in April 1994. -In January, February, and October through December three samples were taken every other week each month, weather permitting, for a total of six per month. From L March through September single samples were taken three times every week in conjunction with the impingement monitoring study. (

A total of 39 species of fish were represented in the January-December samples, equal to the 29-year mean. Winter-early spring samples were dominated by Atlantic cod and American plaice eggs along with sand lance, rock gunnel, and grubby larvae. Late spring-sumner collections, taken from May through July, were dominated by the Labridae-Pleuronectes, L Atlantic mackerel, and Paralichthys-Scophthalmuseggs along with radiated shanny, winter flounder, and Labridae-Pleuronecteslarvae. Late summer-autumn collections (August- L December) were dominated by Labridae-Pleuronectesand Paralichthys-Scophthalmuseggs, along with cunner, Atlantic herring, tautog, and northern pipefish larvae. L Comparisons of ichthyoplankton densities over the 1975-2004 time series suggested that, in most cases, numbers in 2004 were consistent with those recorded since sampling began at L PNPS. Species that appeared abundant in 2004 compared with past years included Atlantic cod and American plaice eggs, and larval radiated shanny and winter flounder. In contrast, Atlantic mackerel eggs, and larval Atlantic menhaden and rock gunnel densities were relatively low. No consistent trends were identified for any species over the complete time series.

Unusually high entrainment densities, as defined under PNPS's sampling plan, were identified on 41 occasions in 2004 and involved four species of eggs and six species of larvae. £ Episodes of high abundance were generally scattered among species and over time and of short duration.

Entrainment and impingement of winter flounder, cunner, Atlantic mackerel, Atlantic menhaden, Atlantic herring, and Atlantic cod were examined in some detail dating back to 1980 using the equivalent adult (EA) procedure. These estimates were compared to commercial and c

recreational landings and local stock size estimates where available. Equivalent adult estimates -

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for winter flounder eggs and larvae lost to entrainment in 2004 were 29,019 age 3 adults compared with a time series average of 8,336 based on three sets of survival values. An average of 99 age 3 equivalent adults (range = 5 to 271) weighing 48 pounds (range = 2 to 132 pounds) was also estimated to have been lost to impingement dating back to 1980. The software program RAMAS Metapop was used to explore further the potential affects of entrainment on the local winter flounder/population. Model runs were completed with fishing mortality and with and without entrainment losses. Results indicated that a 1% decrease in age 0 survival attributable to entrainment could reduce the local adult population by less than 1% to 3% depending on the rate of fishing. Larval entrainment rates as high as 20 and 30%, equivalent to more than 20 or 30 times the rate suggested by the empirical data have little affect on adult stocks when fishing mortality is low (F.= 0.12 to 0.25).

The EA estimate for cunner lost to entrainment in 2004 was 188,107 fish. A total of 206 cunner was impinged in 2004 amounting to 206 additional equivalent adults. Atlantic mackerel equivalent adult losses attributable to entrainment for 2004 amounted to 740 age 1 fish weighing 148 pounds or 304 age 3 fish weighing 213 pounds. Corresponding age 1 values over the 1980 through 2003 time series ranged from 808 (1982) to 19,667 (1989) fish with an average of 5,777.

Age 3 values ranged from 332 to 8,086 with an annual average of 2,375 individuals. Atlantic mackerel are swift swimmers and are not often impinged at PNPS. Mean equivalent adult totals for mackerel amounted to 0.4% of the estimated area 514 commercial and recreational landings.

EA values for menhaden were 50 age 2 fish in 2004, with an additional 749 age 2 equivalents estimated to have been lost to impingement in 2004. These totals appear very low when compared with commercial landings or an estimate of the number of menhaden that spawned in Cape Cod Bay. For Atlantic herring entrainment of larvae in 2004 was equivalent to the loss of 6,922 age I sardines or 3,107 age 3 adults. With the exception of one year (1991) impingement contributed little to losses of herring at PNPS. Lastly, EA values for Atlantic cod in 2004 were very small at 63 age 2 fish which compared with a time series mean of 47. Few Atlantic cod are impinged at PNPS.

Nine lobster larvae were found during the January-December 2004 entrainment sampling period. Previously, a total of 37 lobster larvae have been collected at PNPS dating back to 1974.

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SECTION II INTRODUCTION This report summarizes results of ichthyoplankton entrainment sampling conducted at the Pilgrim Nuclear Power Station (PNPS) from January through December 2004 by Marine Research, Inc. (MRI) for Entergy Nuclear Generating Company, under Contract No.. L 4500528757, in compliance with environmental monitoring and reporting requirements of the PNPS NPDES Permit (U.S. Environmental Protection Agency and Massachusetts Department of L Environmental Protection). Included here is a brief summary of the dominant taxa collected over the course of the year, a review of long-term time trends for the dominant fish eggs and larvae, L and an assessment of numbers entrained for six key species, winter flounder (Pleuronectes americanus),cunner (Tautogolabrusadspersus), Atlantic mackerel (Scomber scombrus), .

Atlantic menhaden (Brevoortiatyrannus), Atlantic herring (Clupea harengus), and Atlantic cod (Gadus morhua). L L

SECTION m METHODS AND MATERIALS Monitoring Entrainment sampling at PNPS, begun in 1974, was originally completed twice per month during January and February, October-December; weekly during March through September; in triplicate at low tide. Following a PNPS fisheries monitoring review workshop in L early 1994, the sampling regime was modified beginning in April 1994. The revised program exchanged replication for improved temporal coverage and has been followed every year since l then. In January, February, and October through December during two alternate weeks each month single samples were taken on three separate occasions. Beginning with March and L continuing through September single samples were taken three times every week. During autumn and winter months when sampling frequency was reduced, sampling was postponed L during onshore storms due to heavy detrital loads. The delayed sample was taken during the subsequent week; six samples were ultimately taken each month. L 3 V Marine Research, Inc. L

To minimize costs, sampling was linked to the impingement monitoring program so that collections were made Monday morning, Wednesday afternoon, and Friday night regardless of tide (see Impingement Section). All sampling was completed with a 60-cm diameter plankton net streamed from rigging mounted approximately 30 meters from the headwall of the discharge canal (Figure 1). Standard mesh was 0.333-mm except from late March through late May when 0.202-mm mesh was employed to improve retention of early-stage larval winter flounder.

Sampling time in each case varied from 8 to 30 minutes depending on tide, higher tide requiring a longer interval due to lower discharge stream velocities. In most cases, a minimum quantity of 100 m3 of water was sampled although at astronomically high tides it proved difficult to collect this amount even with long sampling intervals since the net would not inflate in the low current velocity near high tide. Exact filtration volumes were calculated using a General Oceanics Model 2030R digital flowmeter mounted in the mouth of the net. Near times of high water a 2030 R2 rotor was employed to improve sensitivity at low velocities.

All samples were preserved in 10% Formalin-seawater solutions and returned to the laboratory for microscopic examination. A detailed description of the analytical procedures appears in MRI (1988j. As in past years, larval winter flounder were enumerated in four developmental stages as follows:

Stage 1 - from hatching until the yolk sac is fully absorbed (2.3-2.8 mm TL).

Stage 2 - from the end of stage 1 until a loop or coil forms in the gut (2.6-4 mm TL).

Stage 3 - from the end of stage 2 until the left eye migrates past the midline of the head during transformation (3.5-8 mm TL).

Stage 4 - from the end of stage 3 onward (7.3-8.2 mm TL).

Similarly larval cunner (Tautogolabrusadspersus) were enumerated in three developmental stages:

Stage 1 - from hatching until the yolk sac is fully absorbed (1.6-2.6 mm TL).

Stage 2 - from the end of stage 1 until dorsal fin rays become visible (1.8-6.0 mm TL).

Stage 3 - from the end of stage 2 onward (6;5-14.0 mm TL).

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Samples were examined in their entirety for larval American lobster (Homarus americanus). When collected these were staged following Herrick (1911).

Unusual Entrainment Levels When the Cape Cod Bay ichthyoplankton study was completed in 1976, provisions were added to the entrainment monitoring program to identify unusually high densities of fish eggs and larvae. Once identified and, if requested by regulatory personnel, additional sampling could be conducted to monitor the temporal and/or spatial extent of the unusual occurrence. An offshore array of stations was established which could be used to determine whether L circumstances in the vicinity of Rocky Point, attributable to PNPS operation, were causing an abnormally large percentage of ichthyoplankton populations there to be entrained or, alternatively, whether high entrainment levels simply were a reflection of unusually high population levels in Cape Cod Bay. The effect attributable to any large entrainment event would L clearly be greater if ichthyoplankton densities were particularly high only close to the PNPS shoreline. In past years when high densities were identified, additional entrainment sampling was requested by regulatory personnel and the unusual density in most cases was found to be of short duration (<2 days). With the change in 1994 to Monday, Wednesday, Friday sampling the L temporal extent of any unusual density can be more clearly discerned without additional sampling effort.

Until 1994 "unusually abundant" was defined as any mean density, calculated over three replicates, which was found to be 50% greater than the highest mean density observed during the L same month from 1975 through to the current year. Restricting comparisons to monthly periods damped the large seasonal variation so readily apparent with ichthyoplankton and allowed l tracking densities as each species' season progressed. Starting with 1994 "unusually abundant" was redefined. On a month-by-month basis for each of the numerically dominant species all L previous mean densities over three replicates (1974-1993) were examined and tested for normality following logarithmic transformation. Single sample densities obtained from 1994- L 2003 were added to the pool~within each month. Where data sets (for example, mackerel eggs taken in June) fit the lognormal distribution, then "unusually large" was defined by the overall L 5

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log mean density plus 2 or 2.58 standard deviations. Log densities were back-transformed to make them easier to interpret thus providing geometric means. In cases where data sets did not fit the lognormal distribution (generally months when a species was frequently but not always absent, i.e., many zeros occurred), the mean and standard deviation was computed using the delta-distribution (see for example Pennington 1983). The same mean plus standard deviation guideline was applied.

The decision to rely on 2 standard deviations or 2.58 standard deviations was based on the relative importance of each species. The more critical criterion was applied to species of commercial, recreational, or biological interest, the less critical to the remaining species (i.e.,

relatively greater densities were necessary to flag a density as unusual). Species of commercial, recreational, or biological interest include Atlantic menhaden, Atlantic herring Atlantic cod, tautog and cunner (the labrids; ,Tautoga onitis and Tautogolabrusadspersus), sand lance (Ammodytes sp.), Atlantic mackerel, windowpane (Scophthalmus aquosus), American plaice (Hippoglossoidesplatessoides), and winter flounder. Table I provides summary data for each species of egg and larva by month within these two categories showing the 2004 "unusually high" levels.

A scan of Table 1 will indicate that, in cases where the long-term mean amounts to 1 or 2 eggs or larvae per 100 W3 , the critical level is also quite small. This situation occurred during months when a given species was obviously uncommon and many zeros were present in the data set with an inherent small standard deviation. The external reference distribution methodology of Box et al. (1975) was also employed. This procedure relies on a dotplot of all previous densities for a species within each month to produce a reference distribution. Densities exceeding either 97.5 or 99.5% of the reference set values were considered unusually high with this procedure.'

1Normal distribution curve theory states that 2.5% of the measurements in a normally distributed population exceed the mean plus 1.96 standard deviations ("' s, we rounded to 2 for simplicity), 2.5% lie below the mean minus 1.96 standard deviations. Stated another way 95% of the population lies within that range and 97.5% lies below the mean plus 1.96s. Likewise 0.5% of measurements exceed the mean plus 2.58s, 99% lie withiin the range of the mean

+/- 2.58s, 99.5% lie above the mean + 2.58s.

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i Figure 1. Aerial photograph of the entrainment sampling station in PNPS discharge canal.

r~-- r_- rT7, r-7 r"-I r-, r-i" r-7 r7 r-Ir-1, r-, r. V=

r__ ir r r77 r- 9

Table 1. PNPS ichthyoplankton entrainment values for 2004 by species category and month used to determine unusually high densities. See text for details.

Densities per Long-term Mean + Mean + Previous High 100 m 3

of water: Mpf2n!i 1) CtAl A,.,E

.  ;;uWI.

I zip 9 Wo~u Atox{re v (Year)

A, _,

• svW]

January LARVAE Atlantic herring 2 0.2 1 38.0 (1999)

Sculpin 0.9 2 9.7 (1999)

Rock gunnel 4.0 7 78.1 (2002)

Sand lance 2 5 11 337.0 (1996)

February LARVAE Atlantic herring 2 0.5 0.7 8.0 (2002)

Sculpin 2 65 183.1 (1998)

Rock gunnel 5 177 133.0 (1999)

Sand lance2 16 29 372.9 (1995)

March EGGS American plaice 2 2 3 19.0 (1977)

LARVAE Atlantic herring 2 1.4 2 28.5 (1997)

Sculpin 17 608 454.1 (1995)

Seasnails 0.6 1 14.4 (1980)

Rock gunnel 10.7 723 882.2 (1997)

Sand lance 2 7 164 511.4 (1994)

Winter flounder 2 0.4 0.7 16.2 (1997)

April EGGS American plaice 2 3 32 70.3 (1978)

LARVAE Atlantic herring 2 2 3 38.3 (1999)

Sculpin 15 391 386.2 (1985)

Seasnails 6 10 98.1 (1974)

Radiated shanny 5 7 59.6 (1974)

Rock gunnel 4 142 121.1 (1992)

Sand lance 2 21 998 2590.6 (1994)

Winter flounder" 7 12 198.3 (1994)

May EGGS Labrids 2 36 3514 34050.0 (1974)

Atlantic mackerel2 18 4031 19203.0 (1995)

Windowpane 2 9 147 319.0 (2000)

American plaice 2 2 15 52.6 (1998) 8 Marine Research, Inc.

L Table 1 (continued).

Densities per Long-term Mean + Mean + Previous High L 100 m 3 Of water: Meani 2 Std-dev. 2.58 std.dev. (Year)

May LARVAE Atlantic herring 0.7 1.1 10.5 (1975)

Fourbeard rockling 4.1 8 104.5 (1997)

Sculpin 3 4 78.3 (1997) L Seasnails 7 208 164.4 (1974)

Radiated shanny 7 236 266.9 (1998)

Sand lance 2 37 59 639.1 (1996)

Atlantic mackerel 2 4 377.6 (1998)

Winter flounder2 9 123 573.8 (1998)

June EGGS Atlantic menhaden 2 14 22 799.7 (1998)

Searobins 2 3 128.0 (1987)

Labrids2 Atlantic mackerel 2 958 63 21599 3515 37282.0 (1995) 8193.2 (1990)

L Windowpane 2 27 261 355.5 (1998)

American plaice2 LARVAE Atlantic menhaden 2 6 1

10 3 35.0 (1980) 495.9 (1981)

L Fourbeard rockling .9 634 224.0 (1992)

Hake 0.3 1 50.6 (1998)

Cunner 2 Radiated shanny Atlantic mackerel 2 54.

91 7

87 155 10 2215.6 (1998) 262.2 (1996) 2700.0 (1981)

L Winter flounder' 10 106 813.5 (1998)

July EGGS Atlantic menhaden 2 2 4 59.1 (1978)

Labrids2 615 - 13349 12917.0 (1981)

Atlantic mackerel 2 9 16 119.0 (1981)

Windowpane 2 July 12 156 257.1 (1978) L LARVAE Atlantic menhaden 2 Fourbeard rockling Hake 2

6 0.7 3

9 1

124.2 (1974) 115.8 (1999) 248.4 (1998)

L Tautog 2 2 2 268.6 (1998)

Cunner 2 Atlantic mackerel 2 7

2 318 3

2162.5 (1981) 60.1 (1996)

L L

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Table 1 (continued).

Densities per Long-term Mean + Mean + Previous High 100 m 3 of water: XV1wl ID O ActdA Aa

.1V.

I J SR CtA

>t.wV APU (Year)

August EGGS Searobins 4 6 89.2 (1995)

Labrids 2 23 936 3500.0 (1984)

Windowpane 2 15 136 194.0 (1989)

LARVE Atlantic menhaden 2 0.4 1 47.0 (1997)

Fourbeard rockling 6 10 204.6 (1983)

Silver hake 1 2 78.0 (1999)

Hake 2 4 196.1 (1995)

Tautog 2 1.6 2.2 41.5 (1997)

Cunner 2 10 15 254.0 (1997)

September EGGS Atlantic menhaden 2 42 112 73.2 (1993)

Labrids 2 2 3 112.8 (1993)

Windowpane 11 159 288.8 (1993)

LARVAE Atlantic menhaden 2 1 2 81.0 (1999)

Fourbeard rockling 4 6 68.6 (1993)

Silver hake 2 1 2 46.2 (1999)

Hake 5 9 327.2 (1997)

Tautog 2 1 2 19.3 (1996)

Cunner 2 1 2 42.1 (1993)

October EGGS Atlantic menhaden 2 2 6 163.6 (2002)

Windowpane 2 1 2 30.3 (1997)

LARVAE Atlantic menhaden 2 2.3 4 70.3 (1997)

Fourbeard rockling 1 16 67.9 (1994)

Hake 1 2 13.7 (1985)

November LARVAE Atlantic menhaden 2 0.4 1 57.1 (1997)

Atlantic herring2 4 8 124.8 (1995)

December LARVAE Atlantic herrinf2 2 3 216.7 (1995)

'Geometric or Delta Mean.

2 Species of commercial, recreational, or biological interest for which more critical unusual event level will be used.

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SECTION IV RESULTS L A. Ichthyoplankton Entrained - 2004 Population densities per 100 m3 of water for each species listed by date, station, and L replicate are presented for January-December 2004 in Appendix A (available upon request). The occurrence of eggs and larvae of each species by month appears in Table 2. Ichthyoplankton collections are summarized below within the three primary spawning seasons observed in Cape Cod Bay waters: winter-early spring, late spring-early summer, and late summer-autumn. L Winter-early spring spawners (Januarv-April!

Ichthyoplankton entrained during January through April generally represent winter-early spring spawninig fishes. Many of these species employ a reproductive strategy that relies on demersal, adhesive eggs not normally entrained. As a result, more species are typically represented by larvae than by eggs during the early portion of the year. Over both life stages the, number of species represented in the catch increased from 5 in January to 17 in April. Egg collections in winter-early spring were numerically dominated by the Atlantic cod and witch flounder egg group (gadidae-Glyptocephalus),and American plaice eggs (Figure 2). These -

species accounted for 45 and 41% of the total egg catch during this period, respectively. Eggs in the Atlantic cod and witch flounder group were entrained each month from January through April with monthly geometric mean densities of 0.7, 0.5, 0.05, and 6.9 eggs per 100 m3 of water, 3L respectively. American plaice eggs were found only in April with a monthly geometric mean density of 8.7 eggs per 100 rn3 of water.

In the winter-early spring 16 species of larval fish were collected from the discharge canal. The sand lance, grubby (Myoxocephalus aenaeus), and rock gunnel (Pholisgunnellus) made up the majority of the larval fish collected at this time, contributing 63, 24, and 9% of the L seasonal total, respectively. Sand lance, the predominant larval species throughout the time period, were most abundant during March and April, with monthly geometric mean densities of L 9.8 and 45.7 larvae per 100 m3 of water, respectively. At their peak in April they accounted for 74% of the monthly larval total. The grubby also had peak numbers in April with a monthly i 11 L Marine Research, Inc.

mean density of 12.5 per 100 m3 comprising an additional 17% of the monthly total. For rock gunnel, collected each month, peak density occurred in March with a geometric mean density of 6.1 fish per 100 m3 accounting for 13.5% of the monthly total.

Winter - Early Spring January - April 2004 Eggs Larvae Cod/Witch flounder 62.5%

hoAtlantic cod I 28.9%

tAIothers ck gunnel American plaice 6.1% 8.8%

41.4%

Yellowtail flounder 24.3%

7.9%

Sum of monthly means = 23.23 Sum of monthly means = 119.14 Figure 2: Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the winter-early spring season, 2004. Percent of total and summed monthly mean densities for all species are also shown.

Late Spring-Early Summer (Mav-Julvy May through July represents the late spring-summer ichthyoplankton season, typically the most active reproductive period among temperate fishes. Considering both eggs and larvae, 32 species were represented in the May-July collections, 20 species represented by eggs and 26 species represented by larvae. Numerical dominants represented by eggs included the tautog-cunner-yellowtail flounder egg group (Labridae-Pleuronectes),Atlantic mackerel, and fourspot 12 Marine Research, Inc.

flounder-windowpane egg group (Figure 3). Tautog/cunner/yellowtail flounder eggs accounted for 90% of the late spring-early summer egg catch, peaking in the month of June at a geometric L mean density of 730 per 100 m3 . Labrid egg measurement studies completed at PNPS suggested that the majority of labrid eggs collected near PNPS are cunner (Scherer 1984). Labrid eggs far L exceed yellowtail eggs during the period when they are indistinguishable from each other.

Mackerel eggs accounted for 5% of the seasonal egg collection, peaking in May when they were collected at a mean density of 15.6 eggs per 100 m3. The fourspot flounder and windowpane egg L grouping (Paralichthys-Scopthalmus)accounted for 4% of the spring season egg collection with a seasonal peak of 27 per 100 m3 occurring in June. l Larval collections during late spring-summer contained 26 species with numerical dominants being winter flounder, radiated shanny (Ulvariasubbifurcata), fourbeard rockling, L Atlantic mackerel, and cunner (Figure 3). Winter flounder accounted for 40% of the seasonal total, radiated shanny for 21%, fourbeard rockling for 11%, mackerel for 8% and cunner for 8% L of the three-month total. Winter flounder larvae were observed from May through July (monthly means = 11.3, 5.9, and 0.4 per 100 m3 , respectively), with 69% of the larvae observed in May L decreasing to less than 1% in July. Radiated shanny larvae were recorded throughout the late spring-summer season, peaking in May with a mean density of 14.9 per 100 M3 . Fourbeard L rockling were most abundant in June (monthly mean =15.7 per 100 in3 ) making up 30% of the June larval collections. Atlantic mackerel were found throughout the late spring-summer season; peak seasonal abundance occurred in June with a monthly mean density of 7.6 per 100 n3.

Cunner larvae were observed in June and July (monthly means = 7.0 and 2.5 per 100 mn 3, respectively), and accounted for 48% of the July larval total.

L r

131 L

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Figure 3. Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the late spring-early summer season, 2004. Percent of total and summed monthly mean densities for all species are also shown.

Late Summer - Autumn Spawners (August - December)

This season is typically marked by a decline in both overall ichthyoplankton density and in the number of species collected. Considering egg and larval stages combined, 22 species were taken during the August through December period, 19 species in August declining to 2 species in December. Numerical dominants among the eggs included the tautog-cunner-yellowtail, and fourspot flounder-windowpane egg groups. Seasonal percentages for these eggs were 54% and 39%, respectively (Figure 4). Tautog-cunner-yellowtail flounder eggs were present August through October and peaked for the season in August with a mean density of 13.1 per 100 m3 of water. Fourspot flounder-windowpane eggs were present August through October and peaked in September (monthly mean density = 19.5 per 100 m3 of water).Larval dominants in this late 14 Marine Research, Inc.

summer-autumn season were cunner, Atlantic herring, tautog, norfthern pipefish (Syngnathus fiscus), and fourbeard rockling. Seasonal percentages for these species were 36, 17, 17, 12, and 7%, respectively. Cunner larvae were found from June through September with a seasonal peak during August (monthly geometric mean density of 3.3 per 100 m3 of water). Atlantic herring were present from October through December at geometric mean densities of 0.1, 0.5, and 1.6 per 100 m3 of water, respectively. The December catch accounted for 41% of this species' annual total. Tautog larvae were present from August through October at geometric mean densities of 1.6, 1.2, and 0. 1 per 100 m3 of water. Northern pipefish were recorded at geometric mean densities of 0.9 and 0.1 per 100 m3 in August and September, respectively. Fourbeard rockling were observed in August and October with geometric mean densities of 0.7 and 0.1 per L 100 i 3 , respectively.

L L

L L

L L

L Figure 4. Dominant species of fish eggs and larvae found in PNPS ichthyoplankton samples during the late L

summer-autumn season, 2004. Percent of total and summed monthly mean densities for all species are also shown.

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B. Unusual Entrainment Values Ichthyoplankton densities reaching the unusually high level, as defined under Methods, during the 2004 sampling season occurred on several occasions and involved a number of species. These included American plaice, labrid, Atlantic menhaden, and windowpane eggs as well as the larvae of six species - Atlantic herring, sand lance, winter flounder, hake, tautog, and cunner for a total of 10 species of eggs and larvae combined and 41 specific unusual densities (Table 3).

Several species recorded unusually high densities on either several occasions or during more than a single month. For example, Atlantic herring larvae reached unusually high entrainment numbers on eleven occasions in 2004, once in January, five times in April, once in November, and four times in December (Table 3). On January 7, a new high density of 2.9 herring larvae per 100 m3 was recorded compared with the previous high recorded in 1999 of 1.9 per 100 m3. This was the only case among the 41 observed that a previous high was exceeded.

Sand lance larvae appeared in unusually high numbers on only one occasion, March 31 (604.1 versus unusual level of 164 per 100 M3) exceeding 99% of all previous March values for the species (Table 3).

American plaice eggs reached an unusual level on four occasions in May (26.2, 18.0, 69.7, and 31.4 versus the unusual level of 15 per 100 in3 ); 69.7 per 100 m3 exceeded 99% of all previous May values (Table 3).

Winter flounder larvae reached unusual abundance on four occasions, three in May and one in June. These four occasions exceeded 98% of all previous values for May and June (Table 3). The density of 518 winter flounder larvae per 100 m3 recorded on May 31 approached but did not exceed the previous high of 574 per 100 m3 recorded in May 1998.

Unusual abundance for hake larvae was recorded on two occasions in July with 4.5 and 1.6 per 100 m3 of waterversus the unusual level of 1.0 per 100 m3 and previous high of 248 per 100 m3 .

Tautog larvae reached unusually high densities once during the month of July, on five occasions in August, and four occasions in September, none of which exceeded 7 individuals per 100 in3 or approached previous high values (Table 3). Cunner larvae reached an unusually high 16 Marine Research, Inc.

density once in August, (32.5 versus the unusual level of 15 per 100 in3 ). Labrid eggs attained unusually high densities on five dates in September, (6.8, 37.9, 3.2, 4.3, and 3.3 versus an L unusual level of 3 per 100 in3 ); 37.9 per 100 m3 exceeding 98% of all previous September values. The 1993 density of 42 per 100 m3 of water remains the record high. L Atlantic menhaden eggs were observed in unusual high numbers once in October, 11.6 versus an unusual level of 6 per 100 m3 but well below the previous high of 164 recorded in 2002.

Lastly, windowpane eggs reached unusually high densities twice in October, 7.0 and 4.9 L versus the species' unusual level criterion of 2 per 100 rn3 . Both densities were well below the previous high of 30 obtained in 1997.

C. Multi-year Ichthvoplankton Comparisons A master species list for ichthyoplankton collected from the discharge canal at PNPS L appears in Table 4 for the years 1975 through 2004. A total of 39 species was represented in the 2004 collections, the same as the 1975-2003 time series mean (39 species). l Appendix B (available upon request) lists geometric mean monthly densities along with 95% confidence limits for each of the numerical dominants collected over the January-December L period dating back to 1981. Geometric means are reported because they more accurately reflect the true population mean when the distribution of sample values are skewed to the right as is l commonly the case with plankton data. Generally low values obtained for both eggs and larvae during April-June 1984 and 1987, as well as May-June 1999, were shaded because low through- L plant watervolumes during those months probably affected densities of ichthyoplankton (MRI 1994). Entrainment data collected from 1975-1980 remain in an outdated computer format L requiring conversion before geometric mean densities can be generated. These years were therefore excluded from comparison. To help compare values over the 30-year period, egg data L were plotted in Figure 5 for those species whose combined total represented 99% of the 2004 egg catch. For this figure, cod and pollock eggs were combined in the Gadidae-Glyptocephalus L group; rockling, hake and butterfish made up the Enchelyopus-Urophycis-Peprilusgroup, and labrids and yellowtail flounder were combined in the Labridae-Pleuronectesgroup. For each L 17 L MarineResearch, Inc. L

category shown, the highest monthly geometric means obtained from 1981 through 2003 were joined by solid lines as were the lowest geometric means, and the area between was shaded, indicating the range of these values. Monthly geometric mean values for 2004 were joined by a solid line. Alongside each plot is a bar graph showing annual abundance indices for each year.

These were generated by integrating the area under each annual curve using trapezoidal integrations. One set of bars was based on geometric monthly means and the other, longer time series, on arithmetic monthly means (1975-2004). Appendix B and Figure 6 contain corresponding data for the 13 numerically dominant species of fish larvae, those accounting for 93% of the 2004 catch as well as total larvae (all species combined). As mentioned for eggs, low values obtained for both eggs and larvae during April through August 1984 and 1987 and May-June 1999 were flagged in these figures and omitted from the following discussion.

In many cases densities of fish eggs and larvae vary considerably from year to year. For example, over the 24-year geometric mean time series for Atlantic menhaden eggs, the highest annual abundance index (1,268 in 1982) divided by the lowest (10 in 1992) amounted to 127. In spite of such pronounced variation, no consistent upward or downward trend is apparent over the time series for many species including menhaden and windowpane eggs, sculpin and rock gunnel larvae. Following are noteworthy observations concerning the multi-year time series. Since densities of each ichthyoplankton species rise and fall to zero over the course of each representative occurrence season, inter-year comparisons are often conveniently made within monthly periods.

Atlantic menhaden eggs were relatively uncommon at PNPS during the month of June, reaching'a record low monthly mean-density (0.21 per 100 m3 ) for the 1981-2003 time series in 2004. The' 2004 annual geometric mean index of abundance for menhaden eggs (23) declined from the previous three years (69, 55, and 70 respectively), and ranked the third'lowest over the 1981-2003 time series. The arithmetic mean (71) also decreased compared to the'previous three years (249, 538, and 370 respectively), and ranked the 2Curve integration results in units of (Numbers x days) per 100 m 3 of water.

18 Marine Research, Inc.

eighth lowest over the 1975-2003 time series. In contrast menhaden eggs were entrained at an unusually high density on October 6, 2004 when 11.6 eggs per 100 m3 were L obtained. That density exceeded the unusual level of 6 eggs per 100 m3 and surpassed 97% of all previous October values (Table 3).

The overall seasonal peak abundance periods for menhaden eggs from 1981 to 2003 showed menhaden eggs to be most abundant in June and July followed by a secondary peak in September. The late season, secondary peak extended later in the 2004 season, peaking in October rather than September just as they did in 2002 and 2003. Menhaden eggs collected in October 2004 represented the fourth highest abundance for that month over the time series.

Atlantic cod eggs were typically collected in low numbers at PNPS during winter months L from 1975-1987 (5 per 100 m3 of water, for example). Following 1987 they became uncommon particularly during January and February. None were taken in either month L in 1993 or 1994 and only one was taken in 1995. In 1996 collections rose to three eggs, all taken in February. The gadidae-Glyptocephalusgroup in general showed a significant I decline from 1975 to 1993 (p<0.001), based on a nonparametric sign test (Sprent 1989),

which is consistent with the downward trend reported for Atlantic cod and witch flounder L (Glyptocephaluscynoglossus) stocks, apparently resulting, at least in part, from overexploitation (NOAA 1998, NFSC 1998). In 1998, the annual geometric mean L indices suggested that this decline had ended if not reversed, at least locally, since values for 1994 through 1997 (105, 103, and 112, respectively), appeared stable at about three l times the low values recorded in 1993 (39). The 1998 geometric index (149) was the highest since 1989 (158). In 1999 the geometric mean index dipped to 45, indicating a L possible reversal in the trend. However, for the years 2000 through 2003 the geometric mean indices increased to 194, 246,196, and 463, respectively. In 2004 the geometric L index decreased slightly to 318 but remained relatively strong, with collections representing traditional characteristic peaks for the months of January through February, L May, and November. Early-stage Atlantic cod and witch flounder eggs were collected at a record high density of 6.9 eggs per 100 m3 in April 2004. This is the second year that L 19 L MarineResearch, Inc. L

the April density has set a new record high. Overall an upward trend is apparent in these eggs from 1999 through 2004, which is consistent with an increase in stock biomass and spawning biomass since 1998 for Atlantic cod (NFSC 2001).

Rockling, hake, and butterfish eggs had two new record lows in July and August of 2004 when 1.1 and 1.0 eggs per 100 m3 , respectively were collected. Eggs of the fourbeard rockling and closely related hake (grouped in the early developmental stages with far less common butterfish as Enchelyopus-Urophycis-Peprilus;MRI 1988) have been uncommon in recent years. Trend analysis using the longer-term arithmetic time series indicated that a significant downward trend occurred from 1978 through 1996 (p = 0.05) even with a moderate catch in 1995. In spite of relatively high densities in April 1997, the 1997 indices (3,819 and 1,621) represented only a slight improvement over 1996 (2,889 and 1,299). The 1999 (4,715 and 2,366) and 2000 (7,946 and 4,301) indices indicated an upward trend could be underway. Although the 2001 arithmetic and geometric mean indices declined to 1,897 and 641, respectively, the 2002 arithmetic and geometric means improved slightly to 1,980 and 1,199, respectively. However, in 2003 geometric and arithmetic means declined somewhat to 585 and 1,915, respectively, and continued to decline in 2004 to 438 and 953, respectively.

Fourbeard rockling dominate within this egg grouping based on late-stage eggs as well as larval collections. Since they are a small bottom fish with little or no commercial value, stock size data are not available with which to compare trends. Hake on the other hand contribute to the commercial bottom fishery, and stocks in the Gulf of Maine and northern Georges Bank are both considered to be underexploited. Stock abundance of red hake on southern Georges Bank and in Massachusetts waters are relatively low according to the most recent Northeast Fisheries Science Center survey index (NFSC 2001) consistent with the low egg collections.

Searobin (Prionotusspp.) egg abundance indices increased slightly in 2004 (36 and 21) compared to the 2003 time series lows of 1.8 and 1.5, respectively. Searobin egg abundance indices increased in 1999 (258 and '123) and 2000 (452 and 290) suggesting an upward trend. However, abundance declined in 2001 (108 and 62), 2002 (57 and 33),

20 Marine Research, Inc.

and reached a 1981-2003 time series low in 2003, showing an alternating, intermittent rise and fall in abundance between years since 1987. Massachusetts Division of Marine L Fisheries resource survey trawls showed relatively high abundance during the late 1970's through the mid-1980's followed by a sharp decline through the early 1990's (McBride et l al. 1998). The decline in the 1990's appears to be reflected in the PNPS egg data. l Tautog/cunner eggs, believed to be composed primarily of cunner (Scherer 1984) 6 appeared to be in a downward trend from the late 1970's through 1994 although a sign test failed to confirm it using the conventional 95% significance level (p - 0.055). In L contrast, the arithmetic and geometric indices both showed an increase in density in 1995, the geometric index continuing to rise in 1996. The 1995 arithmetic index appeared exceptionally high and disproportionate to the geometric value due to a single highL density in June (37,282 per 100 m3 of water), which greatly skewed the arithmetic mean for that month. The 1997 arithmetic index (83,356) declined from 1996 (135,791) but remained well above the low values observed in 1990 (58,254), 1991 (36,008), and 1994 (66,078). Indices rose again in 1998, the geometric mean value (50,705) nearly equaling E the 1996 (51,652) index. The arithmetic index was disproportionately high due to two high densities in June 1998. The 1999 and 2000 annual values (29,900 and 28,200, L respectively) were quite similar to each other but represented a decline from 1998. The 2001 geometric index (40,600) represented an increase from 1999 and 2000 and was L comparable to the 1997 value (38,900). However, the 2002 geometric index of 14,709 was the lowest since recording began in 1981 with only thel994 index of 15,263 being L nearly as low. The 2003 arithmetic and geometric mean indices (38,755 and 15, 438) rose slightly from 2002 but both were the third lowest values recorded in the time series. L The 2004 abundance indices increased (77,815 and 32,693) compared to the 2002 and 2003 indices, however, they remain below both time series averages, 138,543 and L 45,330 respectively. In September, labrid eggs were entrained at an unusually high density on five occasions (Table 3); the 37.9 per 100 in3 recorded on September 6 L exceeded 98% of all previous September values.

L 21 L Marine Research, Inc. L

The downward trend noted through 1994 is consistent with observations of finfish in the PNPS area as well as impingement collections at the Station (Lawton et al. 1995).

Changes in sampling protocols at PNPS have negated the ability to monitor general cunner population trends beyond 1994, which in the past were sampled by gill net, trawl, and diver surveys. Numbers impinged appeared to systematically decline from 1980 through 1992 (annual totals dropped from 116 to as low as 2 in 1988), then increased from 1993 (104) through 1995 (288). They remained high in 1996 (211), which appeared to roughly parallel the egg abundance data. The impingement total for 1997 (39) and 1998 (76) represented a substantial drop relative to the preceding four years and appeared out of step with the ichthyoplankton collections. Cunner impingement in 2000 (294) and 2001 (117) was comparable to impingement numbers from 1993 through 1995 (104-288; see Impingement Section). In 2002, the cunner impingement total dropped to 53 and rose in 2003 to 221.

Cunner larval abundance dropped considerably from 2001(geometric mean index

= 1,406) in both 2002'and 2003. The geometric mean index when averaged for 1997-2001 was 2,373 and dropped to 303 (2002) and 115 (2003). Arithmetic mean indices for cunner larvae over the time series (1975-2004) show no apparent trends in entrainment collections, but rather, fluctuate between a few years of relative abundance followed by an occasional year or two in which cunner larvae are less common. For instance, in 1981 the arithmetic mean index for cunner was 10,701 but then declined sharply to 437 in 1982 and climbed to 2,067 in 1983 (Figure 6). This general fluctuation pattern is repeated throughout the time series and likely reflects a localized, dynamic recruitment pattern for this 'temperate wrasse.

Eggs of the yellowtail flounder were relatively abundant in April 1999, 2001, and 2002, but declined somewhat in 2003 and 2004. While early stage eggs of this species are similar to and grouped with the'labrids, they are believed to account for all eggs of that type collected in April since the labrids are not likely to spawn until May. The geometric mean density for-that month in 1999 was 2.4 per 100 3m

, increasing to'4.0 in 2001 and 3.9 in 2002. The April yellowtail flounder eggs' geometric mean index was 1.1 per 100 22 Marine Research, Inc.

m3 in 2003 and 1.6 per100lm 3 in 2004. Stock assessment information shows a slight increase since 1994, perhaps explaining the increase in egg abundance (NFSC 1998).  !

Spawning stock biomass of yellowtail in southern New England has increased since 1998 and they are now listed as overfished according to a first-ever assessment for yellowtail L flounder combining abundance data for both Cape Cod and the Gulf of Maine area (NFSC 2003). l Mackerel eggs typically display a sharp peak in their seasonal abundance curve often with one or two very high densities. For example, in May 1995 a single density of 19,203 eggs per 100 m3 was recorded on May 26, dropping to 557 eggs per 100 M 3 on the 29th. The second highest density occurred on June 9 that year with 4,754 eggs per 100 I 3. Due to these brief sharp peaks, arithmetic and geometric indices are often quite far apart (Figure 5). Mackerel eggs were more abundant from 1988 to 1998 when compared to the 1975 through 1987 period. A sign test using the arithmetic index time series L supported this upward trend (p < 0.006). In 1999 and 2001 however, the numbers decreased significantly to: 1,135 and 727, respectively. This is likely due to the fact that L the main seawater pumps were off for extended periods during the month of May, the peak season for mackerel eggs. In 2002, the geometric mean index climbed to the second highest value in 10 years (11,850) but in 2003 the index dropped 71% to 3,411. In 2004 the geometric mean index dropped 81% to 661, the lowest value in the 1981-2003 time series. The May 2004 monthly mean of 16 eggs per 100 m3 ranked below all other years dating back to 1985, and amounted to less than 2% of the peak observed in 1993 (1,042 per 100 m3 ). Entrainment of high densities of mackerel eggs over the past decade, 1999 and 2001 aside, is consistent with a dramatic rise in stock biomass attributable to l reductions in foreign fishing and underexploitation by U.S. fishermen (Overholtz 1993, NOAA 1998, NFSC 1998). l

• Windowpane eggs, assuming based on larval collections, that they predominate within the Paralichthys-Scophthalmusegg group, increased from 1994 through 2001 which for 2001 l represented the highest geometric mean index (6,377) since 1989 (8,674). In 2002, the same index dropped to 1,396 but rose again in 2003 (1,973) and 2004 (2,843). Over the L 23 L Marine Research, Inc.

entire 30-year time series the arithmetic index for 2004 (5,190) ranked in the middle (13'h) and above the 1975-2003 time series average (4,785). Over the 23-year 1981-2003 geometric mean time series 2004 (2,843) ranked 10th overall, slightly below the series average of 2,923. Windowpane eggs were entrained in the highest numbers during the month of June at a geometric mean density of 27 per 100 m3 of water, consistent with the seasonal peak of past years.

In general these eggs have not shown wide variations in number, at least compared with other species regularly entrained. Massachusetts Division of Marine Fisheries spring and fall trawl surveys, suggest that stocks gradually increased from 1978 to 1995 but then decreased more or less steadily through 2003 (Matthew Camisa, MDMF, personal communication). Over that time series catch did not swing over a very wide range, the low being 2 fish per tow and the high 14 (average of spring and fall surveys).

American plaice eggs' geometric mean index in 2004 (450) was the highest for the 198 1-2003 time series, surpassing the 2001 mean of 414. The 2004 geometric mean index was 2.5 times the series average of 182. American plaice eggs were abundant in April with a mean density of 8.7 per 100 m3 , ranking second behind 2001 (11.8 per 100 in3 ). They were also relatively abundant in May with a geometric mean density of 5.9 per 100 m3 that equaled the 2003 value and exceeded all other May values. American plaice eggs exceeded the level considered to be notable on four occasions in May (Table 3) consistent with the annual ranking.

Plaice egg abundance at PNPS appears to generally follow trends in adult stock size. Entrainment was low in the mid 1980's when stock size was known to be low (NFSC 1998), increased from 1987 through 1992, and decreased slightly through 1996 although remaming above the low of 1990; then rose again through 2001, tapered off in 2002, and increased in 2003 and 2004. A strong year class was produced in 1992 in addition to a subsequent drop in fully recruited fishing mortality from 1992 to 1999 perhaps accounting for the relatively strong egg production near PNPS since then (NFSC 2001). Spawning stock biomass is predicted to increase over the ten-year forecast period from 2000 to 2010 (NEFSC 2001).

24 MarineResearch, Inc.

The total eggs collected, all species pooled together in 2004 (Figure 5), reflects normal peak abundance occurring from April to September. The total egg geometric mean l abundance index for the 2004 year (44,820) was the eighth lowest for the 1981-2003 time series, and well below the series mean of 84,723. The arithmetic mean index increased in U 2004 (88,734) compared to the previous two years, 57,805 in 2002, and 65,881 in 2003.

However, the 2004 arithmetic mean was less than half the time series average of 205,290.

The relatively low indices in 2004 likely reflect to a large extent below average numbers of cunner and mackerel.

Larvae

• Abundance of menhaden larvae dipped noticeably during 2000 and 2001 after four years L of relatively high larval abundance from 1996-1999, climbing slightly in 2002 and dropping again in 2003 and 2004. The 2004 annual geometric mean abundance index (10) was the lowest of all the years sampled, as was the arithmetic mean index (12). The annual geometric mean abundance index for 2000 (21) ranked second for all years D

sampled as did the arithmetic index (44). During 2001 through 2003, the geometric mean L indices rose to 53, 115, and 51, respectively, all below the series average of 240. The arithmetic index rose to 85, 308, and 109, respectively, also below the 1975-2003 time L series average of 369.

Menhaden are coastal migrants that travel in schools that can often be quite dense. L The great variability in numbers of eggs taken at PNPS probably reflects not only numbers of adults in the surrounding waters but variability in the distance from PNPS at L which spawning takes place. Spawning stock biomass increased from 1993 through 1995 (Cadrin and Vaughan 1997), which is consistent with the observed increase in egg and L larval densities in 1997 and larval densities alone in 1997-1999. Currently the stock is believed to be healthy (ASFMC 2004). In addition to traveling in dense schools L menhaden are often attracted to both intake and discharge currents at industrial facilities.

• Atlantic herring larval abundance indices have proven valuable in management of herring U stocks on Georges Bank, Nantucket Shoals, and in the Northeast Atlantic in general (see for example, Smith and Morse 1993). The stock was seriously depleted by distant-water L 25 L Marine Research, Inc. L

fleets during the 1960's and 1970's to the point where no larval herring were found on Georges Bank for a decade (Anthony and Waring 1980, Smith and Morse 1993, Overholtz and Friedland 2002). The stock has increased more or less steadily since 1986 following reductions in fishing pressure to the point where they are abundant on Nantucket Shoals and in the Gulf of Maine-Georges Bank region. Larval collections at PNPS from 1994 through 2002 reflect the general increase in stock size, the geometric mean index for those seven years ranking among the top six. In 2003, however, the geometric mean index (32) fell relative to the 2002 index of 147, and represented a fourteen-year low dating back to 1989. In 2004 the geometric mean index (116) rose relative to the 2003 index, and ranked in the middle (13th) of the 1981-2003 time series.

The 2004 arithmetic mean also increased relative to the 2003 index. Atlantic herring larvae reached unusually high levels on 11 occasions in 2004, (Table 3) suggesting that successful spawning occurred. On January 7, a density of 2.9 per 100 m3 of water set a new January monthly high.

Larval Atlantic herring abundance in 2004 peaked in both April (1.6 per 100 i 3 ) and December (1.6 per 100 i 3 ) consistent with the historical pattern. Peak abundance indices shift somewhat from year to year from the long-term trend most likely due to such abiotic factors as water temperature. For example, the major spawning for Atlantic herring in the NW Atlantic traditionally occurs from late August through November (Collette and Klein-MacPhee, 2002), but during unseasonably cold winters this spawning seasonality usually shifts later into December.

Fourbeard rockling larvae were abundant in 1998 and 1999 particularly in July when the monthly geometric means of 32 and 30 per 100 m3 respectively exceeded the previous July high of 6 per 100 m3 dating back to 1981 (Figure 6). In 2000, the annual geometric mean index dropped precipitously (50) and represented the lowest index dating back to 1981. In 2001, the geometric mean index rebounded to 607, the fourth highest since 1990. However, the geometric mean index for 2002 dropped to its third lowest over the 24-year sampling period. In 2003, the geometric mean index dropped to a time series low of 47, under one tenth the series average (509). In 2004, the geometric mean index 26 Marine Research, Inc.

increased relative to the 2002 and 2003 indices to 528, ranking 10 th highest in the time series and above the series average. The September monthly mean (0.0 per 100 m3) set a X new monthly low for the time series, and was the first time that no rockling larvae were collected during this month. In spite of these swings in abundance, no consistent trend over the times series is evident.

As mentioned above under eggs, the rockling is a small bottom fish with little or l no commercial value and stock size data are not available with which to compare trends.

Abundance indices for larval hake increased slightly in 2004 (47 and 23) compared to the 2003 time series lows of 16 and 9, which were far below the series averages of 847 and L 229. In spite of generally low abundance hake larvae reached unusually high densities on two occasions in July 2004. The 4.5 per 100 m3 recorded on July 5 exceeded 91% of all L previous July values (Table 3). Data available through 1999 suggest that hake stocks in southern New England have declined by about 50% since the late 1960's, and surveys in L Massachusetts waters confirm that, with the possible exception of 1999, abundance is relatively low (NFSC 1998, Robert Johnston, Massachusetts Division of Marine [

Fisheries, personal communication). Although increased recruitment has helped the southern stocks of red hake (NFSC 2001), the status of white hake is currently listed as l overfished (NFSC 2001). Time series highs in larval abundance at PNPS in 1997 (994) and 1998 (932) may indicate production of strong year classes or simply reflect a localized spawning aggregation, especially since the trend did not continue for the last several years.

• Sculpin abundance has remained relatively stable over the 30-year arithmetic mean time series (Figure 6). A slight increasing trend occurred from 1977 through 1989 and a L secondary peak in 1997 (geometric mean index = 2,249, arithmetic mean index = 5,058).

After dropping in 1998 to 1,086, the geometric mean index climbed to 1,668 in 1999 and L 1,528 in 2000 before declining to 958 in 2001. The sculpin geometric mean index for 2002 (2,428) rebounded to the third highest since 1981 and the highest since 1988. In L 2003 and 2004, the means fell to 988 and 766, respectively, both below the time series average of 1,393. A new monthly low was set in February when no larvae were collected L 27 L Marine Research, Inc.

for the first time during this month. The major species within this genus entrained at PNPS is the grubby. Since these fish are small and have no commercial or recreational significance, no stock size data are available with which to compare the larval abundance patterns.

• For larval seasnail the geometric mean index rose to a 7-year high in 2004 (233),

exceeding the 2002 five-year high of 202. In 2003, these larvae dropped to a 1981-2002 time series low geometric mean index of 27. The arithmetic mean index also reached a 1975-2003 time series low of 30. Since these fish typically reach a length of less than 6 inches and they have no commercial or recreational significance, no stock size data are available with which to compare the larval abundance patterns.

• Tautog abundance in 2004 (geometric mean index 172) increased relative to the 2003 abundance (64) which declined slightly from that of 2002 (73) and more significantly from the 2001 five-year high of 268. Tautog larvae in 2004 exceeded the unusual density level once in July, five occasions in August, and four occasions in September (Table 3).

On two occasions in September, the 1 st and 8th, the mean densities of 6.2 and 7.1 respectively, exceeded 96% of all previous densities for September. The arithmetic mean index (1975-2003) extends over a longer time series than the geometric mean index and historically shows peaks and ebbs from year to year with no apparent long-term trend.

• Cunner larvae were more common in 2004 (geometric mean index = 373) than the previous year (115), however their abundance was still below the time series average of 1,144. No consistent long-term abundance trends are apparent for this species. Cunner reached an unusually high abundance in 2004 on August 6t at a mean density of 32.5 per 100 i 3, exceeding 93% of all previous August values (Table 3). Current stock size data for cunner are not available but tautog are believed to be 'overfished and at very low levels (NFSC 1998). However, recent data indicate that fishing mortality rates have declined from 1993 to 2000 and recreational landings have decreased from 1987-2001 (Stirratt 2002). Hopefully the stock will rebuild.

• Larval radiated shanny were relatively common in 2004 with a geometric mean index of 574 continuing a 4-year increase in abundance since a 12-year low in 1999 (geometric 28 Marine Research, Inc.

mean index = 73; Figure 6). Radiated shanny larval abundance rebounded in 2000 (geometric mean index = 239), 2001 (geometric mean index = 604), and.in 2002 (651),

the highest in seven years and the second highest for the time series. The geometric mean indices for 2001 and 2002 were both above the mean over the 1981-2003 time U series average of 395 per 100 m3 . The geometric mean index for shanny in 2003 (452) represented a reversal in the upward trend but remained above the 23-year average. May l is typically the month of highest larval abundance for shanny. The monthly geometric mean for May 2004 (14.9 per 100 M 3 ) was above the time series average for the month of 9.8 per 100 in3 . During June, radiated shanny larval abundance typically ebbs and in 2004 the geometric mean of 3.5 remained above the series average for this month (2.2 per 100 m3 ). The June 2004 monthly geometric mean was the fourth highest recorded over the time series 1981-2003; the previous high values were 9.7, 6.3, and 3.6 recorded in 1996, 1994, and 2003, respectively. The arithmetic mean index for 2004 (1,594) was above the 1975-2003 time series mean index of 817. Since this is a small, rather inconspicuous bottom fish, relatively little is known of its habits and data are not L available concerning population trends.

Larval rock gunnel abundance declined in 2003 and 2004 from the previous three years L when they were collected in above average numbers. The 2004 annual geometric mean of 289 amounted to 73% of the 1981-2003 time series average (1,073), and was the third j lowest value in the time series. The arithmetic mean index (638) was 66% of the 1975-2003 arithmetic mean index time series average of 1,892, and ranked eighth lowest. For L 2002, the geometric mean abundance index of 3,040 was appreciably greater than the 23-year average. Overall, however, there was no obvious or statistically significant trend from 1975 to 2004, although there appeared to be intermittent highs in relative abundance followed by one or two-year declines with the peak abundance indices generally L increasing over the 1981-2004 time series. The appearance of rock gunnel larvae from February through April, the three months when they typically are most abundant, fell L below the time series mean for these months in 2004 consistent with the overall annual 29L Marine Research, Inc.

index. Because the rock gunnel is a small bottom fish with no commercial or recreational value, abundance data are not available with which to compare the entrainment estimates.

For sand lance the 2004 geometric mean index (1,824) fell only slightly below the time series average of 1,859. The arithmetic mean index (5,029) remained above the time series average of 3,631 (Figure 6). Sand lance reached an unusually high density on March 31, with 604 per 100 m3 exceeding 99% of all previous March values. Overall geometric mean indices peaked in 1996 (6,156) and the arithmetic index peaked in 1994.

The geometric mean index has increased three-fold in the last II years (1994-2004, mean index = 2,820) compared with the first 13 years (1981-1993 mean index = 1,054) indicating a general increase in abundance that began in 1991 after the relatively poor showing of sand lance from 1987-1990.

The 2004 abundance curve generally mirrored the curve for the historical record with highest abundance during the months of March, April, and May. Historically, April represents the peak month for sand lance larval abundance in Cape Cod Bay and data for 2004 follow this trend with an April geometric mean of 46 per 100 m3. A single sand lance larva was collected in November representing the beginning of the 2005 spawning season. The November appearance of sand lance suggested that the 2005 spawning season may have started earlier than in previous years with larvae typically appearing first in December.

Unfortunately the sand lance has little to no commercial or recreational value, and therefore abundance data are unavailable to compare to the entrainment estimates.

However, sand lance do play an important role in community ecology in that they are an important prey source for a number of finfish species including several of the dominant species discussed above: mackerel, cod, hake, plaice, and yellowtail flounder (Winters 1983). Adult sand lance are also an important key prey species in the diet of several baleen whales that migrate to or through Massachusetts and Cape Cod Bays seasonally such as humpback (Megaptera novaeangliae) and finback whales (Balaenopteraphysalis) and influence these whales' seasonal migrations (Weinrich et al 1997; Hain et al 1995).

Traditionally, other dominant prey sources for humpback whales have been Atlantic 30 Marine Research, Inc.

herring and Atlantic mackerel and, as both these prey sources declined in abundance during the late 1970's and early 1980's, humpback whales began targeting sand lance as U their main prey source for our region (Kenney et al 1996). The tourism industry generated from commercial whale watching has grown since the end of industrial whaling L and has developed to where it plays an important economic role in the New England inshore waters.

Mackerel larvae and eggs, as mentioned above, typically display a sharp peak in their abundance curve often with one or two very high densities. Due to these brief sharp peaks, arithmetic and geometric indices are often quite far apart (Figure 6). Mackerel larvae geometric mean index reached a 5-year high in the 2004 collections at 251. The geometric mean index for 2003 (36) represented a decline from the previous three years, 2002 (70), 2001 (159), and 2000 (131). The arithmetic mean index was high in 1981 (10,030) and again in 1995 (12,086). In general, the arithmetic mean indices increased L from 1975 until 1995 and then declined. The 2004 value (726) ranked in the middle (15'h) for the 1975-2003 time series; however, it was well below the time series mean of l 1,864. The peak abundance months for larvae over the historical time series are May and June with geometric mean averages of 0.8 and 9.9, respectively. During 2004, the May l and June geometric means were below these averages at 0.09 for May and 7.6 per 100 m3 of water for June.

• Winter flounder larvae, a species of considerable recreational and commercial interest and value, are typically among the numerically dominant members of the larval fish -

community around PNPS in May and the first part of June. The annual geometric mean index for 2004 (539) increased from the 195 recorded in 2003. The 2003 index was L lower than the previous two years, 575 for 2002 and an all-time high of 2,307 for 2001.

The 2004 index was slightly higher than the 1981-2003 time series mean of 523. Winter L flounder larvae reached unusually high densities on three occasions in May and on one occasion in June (Table 3). On all four occasions the densities exceeded 98% of all L previous May and June values. Although the 2004 May collections had unusually-high-density events, the monthly geometric mean of 11.3 per 100 m3 was below the monthly L 31 Marine Research, Inc. L

time series average of 13 per 100 rn3. The 2004 arithmetic index was 3,047, which ranked fourth over the 1975-2003 times series, and was more than 2.5 times the time series arithmetic mean of 1,107.

The most recent stock assessment for winter flounder in Southern New England/Mid-Atlantic stocks, including offshore Cape Cod catch data through 2001, shows winter flounder are currently overexploited (NFSC 2003). This most recent stock assessment also estimated the 2001 year class to be the smallest in 22 years. However, winter flounder stocks in the Gulf of Maine are doing better than the Southern New England stock, are currently listed as not being overfished, and are considered to have been rebuilding since 1995 (NFSC 2003).

The total for larvae collected in 2004, all species pooled together (Figure 6), mirrors the time series (1981-2003) abundance curve, showing major peak abundances from April to June. Data collected over the 1981-2003 time series have shown April as the traditional peak in larval abundance (average geometric mean of 90 per 100 n3 ) when several species are abundant including: winter flounder sand lance, rock gunnel, seasnail, and sculpin. The 2004 abundance curve differed from the historical curve in February when larval density set a time series low at 1.0 per 100 m3 . The total larval arithmetic and geometric mean indices for 2004 (16,322 and 8,897, respectively) increased from 2003 (10,727 and 6,614), however, both were below the time series averages of 21,629 and 11,827, respectively.

32 Marine Research, Inc.

Figure 5. Geometric mean monthly densities per 100 m3 of water in the PNPS discharge canal for the eight numerically dominant egg species and total eggs, 2004 (bold line).

L Solid lines encompassing shaded area show high and low values over the 1981-2003 period. L Brevoortia tyrannus Labridae-Pleuronectes Gadidae-Glyptocephalus Scomber scombrus Enchelyopus-Urophycis-Peprilus Paralichtys-Scopthalmus L

Prionotusspp. Hippoglossoidesp latessoides l Total eggs L

To the right are plotted integrated areas under the annual entrainment abundance curves for 1975-2004. An asterix above 1984, 1987 and 1999 marks the three years when values may have been low due to low through-plant water volumes from April-August. An asterix above 1976 indicates abundance value may be low due to absence of sampling during January - late April; see text for clarification. Light bars represent indices based on monthly means arithmetic means, L solid bars (1981-2004) indices based on monthly geometric means.

Occasionally bars were rescaled to improve readability. The actual value in those cases is L printed above the bar.

L 33 MarineResearch, Inc.

L

Brevoortia tyrannus Eggs 100 _ _-2000 z 67.000

--- 23.232 10 15 0 --- - - -- -

3,023 50 0.01 Year 0103 30204 J F M A M I I A S O N D ( Abundanc Indexbasedon:

Month 6Arimetic mans *Geometric means

[ciligh/Low .w204 Gadidae - Glyptocephalus AS Ei~

20-I l0t I 0.1 5t 30 75

• 0.01 75 77 79 *1 83 85 87 89 91 93 95 97 99 01 03 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 Year J1 F M A M J I A S ON D Abundance Index based on:

II month

{PArthmetic meansINGeometric mean)~

[OHigldaow **200 Inluld.+/-sG. mwinhw. P.,i-wts, a d 0 weg at n Figure 5 (continued).

34 Marine Research, Inc.

L Enchelyopus - Urophycis - Peprilus Eggs A 1000 e~ee_-_--__

e-e

-E__-

L

- - - - - - - - - --5A - - - - - - - - -E 300 I -_- - m I

8 .1 0.1 0.01 L

0.001 I F M A M 1 J A S O N D 75 77 79 8S 93 S5 87 89 91 93 95 97 99 Ot 03 76 78 80 82 4 86 88 90 92 94 96 96 Year Abundance Indcx Waed on:

90 02 04 L

Month L

Ip Altmaic meaw ftGoomettic ien.)

[OllightLow 004)

Includes.P.ambrimto~l spp.,and P. Mnldauvdn L

Prionotusspp.

,00 L

,0

---

s----------

L I ---

--- I 0.1

- - - - - -- N - - -- --

0.01 I

75 77 79 8S 83 85 87 89 91 93 95 97 9 01 03 76 7S 80 82 84 86 88 90 92 94 96 98 00 02 04 Year 0.001 J F M A M

([3High/Low I

Month q

J A 2004 S 0 N D Abundmnc, Index b~sd on: MJ tpArithmetic mcans WGeometric c1 L

Figure 5 (continued).

L 35 L MarineResearch, Inc.

Labridae - Pleuronectes Eggs IODDO 1000 100 I

10 I

8 1 0.I I

0.1 0.01 75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 76 78 So S2 84 86 8890 92 94 96 98 00 02 04 0.001 Year JF PM AM J J A S ON D f bidneIndes based on: )

Mouth 6pArithmetic means Swacmeti. meW frHfigh/Lo. -2004 Includes LaIbridae and P.fti'rughtezta Scomber scombrus 1oa IEgos I 0 200 1000 100 I ----------

10

• 1 a EE 0o - --

A

0. aM 10 0.01 75 77 79 1S83 85 87 89 91 93 95 97 99 01 03 76 78 S0 S2 84 86 88 90 92 94 96 98 00 02 04 Year 0.001 y 4 M A' M iIw I -,A S 0 N" D" {Abundance Index based on:)

6OArthmertc means NGeomweic av Month Figure 5 (continued).

36 Marine Research, Inc.

Paralichthys- Scophthalmus L ooo EcreSL 1000 - - -- - - 12 1000 0.1 9 *I 03 75 77 79 81 3 85 7 8991 9395 97 9901 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 I.0 F M AM JI 1 A S O N D AbundanceGIndxbsmed on

. .0 Month .mL zTg WL. 2004) L Hippoglossoidesplatessoides Eggs 100 1600 10 - - - - - - - - - 1200 - - - - - - - - - - - - - - - - - - - - - - _

- - - S - - - -- - - - - - - -

0. 4 00 ---- --

U aa o *200 -

0.01 75 77 79 81 83 85 87 89 91 93 95 97 9901 03

-' 76 7889082 8486 8890 9294 96 9800 0204 Year

0.0 01AbnacIdebaeo

J1 F M A M I J A S 0 N D Audnenebsdn Month Arithmetic meansEGeometricme 3?

L DOligh/Low 0020D04 Figure 5 (continued).L 37L Marine Research, Inc.

Figure 5 (continued).

38 Marine Research, Inc.

L Figure 6. Geometric mean monthly densities per 100 m3 of water in the PNPS discharge canal for the thirteen numerically dominant larval species and total larvae, 2004 (bold line). Solid lines encompassing shaded area show high and low values over the 1981-2003 period.

Brevoortia tyrannus Tautogolabrus adspersus Clupea harengus Ulvariasubbifurcata Enchelyopus cimbrius Pholis gunnellus Urophycis species Ammodytes species Myoxocephalus species Scomber scombrus Liparis species Pleuronectesamericanus Tautoga onitis Total larvae To the right are plotted integrated areas under the annual entrainment abundance curves for 1975-2004. An asterix above 1984, 1987 and 1999 marks the three years when values may have been low due to low through-plant water volumes from April-August. An asterix above 1976 indicates abundance value may be low due to absence of sampling during January - late April; see text for clarification. Light bars represent indices based on monthly means arithmetic means, solid bars (1981-2004) indices based on monthly geometric means. L Occasionally bars were rescaled to improve readability. The actual value in those cases is printed above the bar. L L

39 I MarineResearch, Inc.

Figure 6 (continued).

40 Marine Research, Inc.

I Enchelyopus cimbrius Larvae L

10 2

L 0.001 0

75 77 79 SI83 85 1S7 89 91 93 95 97 99 01 03 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 year L

J P M AMJ J A S O N D lsneeIndex basd on:

Montb Mw:

i d/ oi l

LOAffmcdc nscans NGcomeric mau L

L Urophycis spp.

Larvae L

100 10 4

I _

L

11 I - - - - - - , -

I 3 L

II 0.1' IC --- -- - - - - - - - - - - - - - -

L 0.01

-- jj 75 77 79 Sl3 85 87 89 91 93 95 97 99 01 03 76 78 80 82 84 86 S8 90 92 94 96 98 00 02 04 L

0.001 J

F MA

. w M I Mouth rr3HgMk,.ow J A S

-200D4)

N D Year

. Abundance Index based on:

I6Arfitmeic means Geometric I

.J al L

Figure 6 (continued).

L

41. L Marine Research, Inc.

Myoxocephalus spp.

Larvae 100 ============== -- 7 10

~~--------

Cz 0.1 t; I 2 71

-7 - -- -

I 87 89 91 93 95 97 9 01 03 86 88 90 92 94 96 98 00 02 04 0.001 Year J F MA M J J A SO N D r Ab- idance Index based on:

Month LCArithmed icmeans 1111mmetnc maS f:lHigh/Low 200D4)

Liparisspp.

Larvae 00 2500 10 _ _ _ --- _-_-_---

- -- -- -- 2000

~~ --- -*

0.02 -

0 757779818385878991939597990203 767880828486889092949698000204 0.002 Year F M A M J J A S O N D Month 6ritfimetic means 111Geomeetrc

[3High/Low 4*2 Figure 6 (continued).

42 Marine Research, Inc.

I Tautoga onitis I Larvae 100 2000 1500

_ 1000 75 77 79 t183 S5 87 S9 91 93 95 97 99 01 03 76 722 0 22 84 S6 88 90 92 94 96 98 00 02 04 0.001 Year I F M A Mf I I A S O N D Abundance Index based on:

Monlth lnrimetic mean Gcornetic m DHNighLow *2004)

L Tautogolabrusadspersus

,000 - - -= - - - -=

Larvae L 100 L I

,0 I0 II i -iii----* --- -I-0.1 Ii I 0.01 75 77 79 St S3 S5 87 29 91 93 95 97 99 01 03 76 78 80 82 84 26 28 90 92 94 96 9S 00 02 04 L

0.001 Year J F M AM J JA SO0 D f Abundance Index basd on:

Month 6pArthmetic meauzWGeometric mean Figure 6 (continued).

43 L

Marine Research, Inc.

Figure 6 (continued).

44 Marine Research, Inc.

Ammodytes spp.

,000 Larvae

====== = = = = = = = ==

EEEEEEEEEEEEEEEEEEEEE too 10 _ i___----------

I I

I I

.0l 0.01 7577798183SS878991 939597990103 76 78 80 82 84 86 88 90 92 94 96 9 00 02 04 0.001 - Year J F M Abnac Ine bsd on:

Month 6CAridunctic man lGoomelicumel ED1-igh/-L-Ow O20-04 Scomber scombrus Larvae 100 - . .0 12,086 10,030 II 8

.0 I 6 I I

.i 8 0.1 EE~

---

---- E---E 4 2 -----; --I1.1--n tt 0.01 o ' jI4.L4.L4.'M

'1 i JLJ L 11! 44 . . . .

75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 L

0.00l _e *

• l - -. Year I F M A M J J A S O N D Abundance Index based on:

Month tpArifnctic means INGoomcuic me1 (CWgh3F/w 4,2004)

Figure 6 (continued).

L 45 L MarineResearch, Inc.

Pleuronectesamericanus 100

,0 I E~~~~~~ - - - - -A - - --

I I, 0.1 __-!,f- - - - - - - -- -

0.01 75 77 79 81 83 85 87 89 91 93 95 97 99 Of 03 76 78 82 s0 84 86 so 90 92 94 96 98 00 02 04 0.001 _ Yau j F M AM~ IJA SON Dl Abudance Index basedon:

Mooth p6ritfmedc means =Geometricm CC~gh/L~ow 002OD4 Total Larvae 1000 I I 8

.S I

i: -::::

-=g- g ijrw44

-17iA-75 77 79 St 83 85 87 89 91 93 95 97 99 01 03 II I I I , I K' 76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 0.001 Year J P M A M I I A S 0O N D Abundance Index bisd on:

Month p6rithmetic means Geomeutic mea41 (CiighLow r 2004 Figure 6 (continued).

46 MarineResearch, Inc.

Table 2. Species of fish eggs (E)and larvae (L) obtained in ichthyoplankton collections from the Pilgrim Nuclear Power Station discharge canal, January-December 2004.

2004 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Species American eel Anguilla rostrata Atlantic menhaden Brevoortiatyrannus E/L L L L E E/L Anchovy Anchoa spp. E E E/L L L L E/L Atlantic herring Rainbow smelt Cusk Clupea harengus Osmerus mordax Brosme brosme L I L L E

L L E

L L. L L E

L Fourbeard rockling Enchelyopus cimbrius E E E/L E/L EIL E/L E E/L EL Atlantic cod Gadus morhua E/L M E/L E/L E ML E E/L E/L Pollock Pollachiusvirens L L L Haddock Melanogrammus aeglefinus E/L EIL L E/L Silver hake Atlantic tomcod Hake Merluccius bilinearis Microgadustomcod Urophycis spp L

E E

E E/L EIL E

E/L E

E E

E E

L E/L L

Goosefish Lophius americanus E E Silversides Northern pipefish Searobins Men idia spp.

Syngnathusfuscus Prionotusspp.

L L

E L

L E

L E

L L

L E

L Grubby Myoxocephalus aenaeus L L L L Longhorn sculpin M octodecemspinosus L L L Shorthorn sculpin M scorpius L L L Alligatorfish Asidophoroidesmonopterygius Seasnail Liparis adanticus L L L L Gulf snailfish Black sea bass L coheni Centropristisstriata L L L

Scup Stenotomus chrysops L L Weakfish Wrasses Tautog Cynoscion regalis Labridae Tautoga onitis E

E/L E

E/L L

E L

E L

E L

E L

L E

EAL I

Cunner Tautogolabrus adspersus E/L L L L E/L Snakeblenny Radiated shanny Rock gunnel Lumpenus lumpretaeformis Utvaria subbifurcata Pholis gunnellus L L L L

L L

L L L L L L

I Wrymouth Crytacanthodesmaculatus L L L Sand lance Ammodytes sp. L L L L L L L Seaboard goby Gobiosomaginsburgi L L Atlantic mackerel &omber scombrus E/L E/L L L E E/L Lumpfish Cyclopterus lumpus Butterfish Peprilus triacanthus n Smallmouth flounder Etropus microstomus E E E E Windowpane Scophthalmus aquosus E/L EAL E/L E/L E/L E/L E/L Summer flounder Paralichthysdentatus Fourspot flounder P. oblongus EIL E/L E/L E/L Hogchoker Trinectes maculatus Witch Flounder Glyptocephalus cynoglossus EIL E EIL E EI/L American plaice Hippoglossoidesplatessoides E/L E/L E E/fL Winter flounder Pleuronectesamericanus E E/L E/L L L L E/L Yellowtail flounder P.ferrugineus E L E/L Smooth flounder P. putnami L L Number of species 5 3 11 17 20 22 22 19 12 9 4 2 39 L

I 47 i

Table 3. Ichthyoplankton densities (number per 100 m? of water) for each sampling occasion during months when notably high densities were recorded, January - December, 2004. Densities marked by + were unusually high based on values in Table 1. Numbers in the last column indicate percent of all previous values during the month which were lower.

Atlantic Herring Larvae January 2 0 7 2.9 + 100 16 0 19 0 21 0 26 0 Previous high: 1.9 (1999)

Notice level: 1.0 Sand Lance Larvae Atlantic Herring Larvae March 1 16.2 April 2 7.3 + 92 3 3.4 5 1.2 5 3.3 7 0.0 8 5.6 9 5.8 + 89 10 18.4 12 9.2 + 95 12 26.4 14 0.9 15 0.0 17 0.0 17 0.8 19 4.7 + 85 19 9.5 21 0.6 22 19.9 23 1.3 24 2.2 26 2.6 26 42.5 28 0.0 29 1.7 30 3.3 + 80 31 604.1 + 99 Previous high: 38.3 (1999)

Previous high: 708 (2002) Notice level: 3.0 Notice level: 164.0 American Plaice Eggs Winter Flounder Larvae May 3 12.2 May ,3 3.5 5 26.2 + 97 5 0.6 7 18.0 + 94 7 0.9 10 7.9 10 0.0 12 4.8 12 0.5 14 14.3 14 18.7 17 13.6 17 8.5 19 69.7 + 99 19 0.6 21 31.4 + 97 21 0.0 24 0.0 24 6.5 26 1.2 26 164.8 + 98 28 1.3 28 289.0 + 99 31 518.4 + 99 Previous high: 87.2 (2003)

Notice level: 15.0 Previous high: 573.8 (1998)

Notice level: 123.0 48

Table 3 (continued).

Winter Flounder Larvae Hake Larvae June 2 88.6 July 5 4.5 + 91 4 219.9 + 99.5 7 1.6 + 86 7 50.3 9 0.0 9 2.1 12 0.0 11 12.1 14 0.0 14 2.9 16 1.0 16 18.2 19 0.0 18 9.2 21 0.0 21 23 25 16.4 2.7 17.4 23 26 28 0.0 0.0 0.0 L

28 0.0 30 0.7 Previous high: 248.4 (1998)

Notice level: 1.0 Previous high: 814 (1998)

Notice level: 106 L

Tautog Larvae July 5 7

Tautog Larvae 1.3 0.0 August 2 4

0.0 0.0 L

9 7.6 + 86 6 0.0 12 14 16 0.0 0.7 2.0 9

11 13 3.2 0.0 5.3

+

+

85 89 L

19 0.5 16 5.6 + 89 21 0.0 18 3.8 + 87.5 23 1.6 20 3.1 + 85 26 0.0 23 1.5 28 1.9 Previous high: 268.6 (1998) 25 27 30 1.2 0.0 0.0 L

Notice level: 2.0 Previous high:

Notice level:

41.5 (1997) 2.2 L August 2 Cunner Larvae 11.7 September 1 Labrid Eggs 6.8 + 91 L

4 9.0 3 0.5 6

9 32.5 14.2

+ 93 6 8

37.9 3.2

+

+

98 81 L 11 11.5 10 1.0 13 1.8 13 2.6 16 4.2 15 4.3 + 86 I 18 3.8 17 3.3 + 81 20 3.1 22 0.0 23 25 1.5 1.2 0.0 24 27 0.0 0.6 E 27 30 0.0 Previous high: 254.0 (1997)

Previous high:

Notice level:

112.8 (1993) 3.0 L Notice level: 15.0 L

49 L

Table 3 (continued).

l Tautog Larvae Atlantic Menhaden Eggs September 1 6.2 + 96 October 4 0.0 3 0.0 6 11.6 + 97 6 1.5 8 0.0 8 7.1 + 96 18 0.0 10 0.0 27 0.0 13 0.6 29 0.0 15 1.6 17 3.3 + 90 Previous high: 163.6 (2002) 22 0.0 Notice level: 6.0 24 2.4 + 85 27 0.0 Previous high: 19.3 (1996)

Notice level: 2.0 Windowpane Eggs Atlantic Herring Larvae October 4 1.6 November 3 0.0 6 7.0 + 93 8 0.0 8 4.9 + 88 10 0.0 18 0.0 12 0.0 27 0.0 17 0.7 29 0.0 19 1.6 22 0.9 Previous high: 30.3 (1997) 24 0.0 Notice level: 2.0 26 9.0 + 76 Previous high: 124.8 (1995)

Notice level: 8.0 Atlantic Herring Larvae December 3 2.6 6 0.0 8 11.6 + 90 10 0.0 15 2.2

- 17 10.1 + 89 20 4.3 + 83 22 i 12.0 + 90 24 0.0 Previous high: 216.7 (1995)

Notice level: 3.0 50

Table 4. Species of fish eggs (E) and larvae (L) collected in the PNPS discharge canal, 1975-2004. General periods of occurrence for eggs and larvae combined are shown along the right side; for the dominant species, periods of peak abundance are also shown in parentheses.

Species 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 Anguilla rostrata J' J J J J i Alosa spp. L L J L L Brevoortiatyrannus E/L E/L E/L E/L E/L E1L E/L E/L E/L E E/L EIL El E/L E/L Clupeas harengus L L L L L L L L L L L L L L L Anchoa spp. L L L L L L L L L L L L L A. mitchilli E E E E EIL E E E Osmerus mordax L L L L L E/L L L L L L L E/L Brosme brosme E/L E/L Ei.L E/L EIL E E E Enchelyopus cimbrius EaL E/L E E/L E/L E/L E/L EaL EaL EaL E/L EdL E/L E/L E/L Gadus morhua E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L El E/L ElL E/L Melanogrammus aeglefinus L E/L E/L E/L L L E E Merluccius bilinearis E/L E/L E/L E/L E/L E/L E/L EIL EIL E/L E/L E/L E/L E/L E/L Microgadus tomcod L L L L L L L L L L L L Pollachiusvirens E/L E/L E E/L E/L EIL L L E/L L E/L L L Urophvcisspp. E/L E/L E/L E/L E E/L E/L E/L E/L E' E/L E/L E/L E/L E/L Ophidion marginatum Lophius americanus E/L E E/L E/L EML L ELL E/L E E l E E E E/L.

Strongylura marina L Fundulus spp. E E F. heteroclitus E F. majalis J Menidia spp. L L ii E/L E/L E E/L L L L L L L M. menidia E/L E/L E L Syngnathusfuscus L L L. L L L L L L L L L L L L Sebastes norvegicus L Prionotusspp. E/L E E E E/L E/L E E/L E/L E/L E/L E/L E/L E Hemitripterusamericanus Myoxocephalus spp. L L L L L L. L L E/L L E/L L L L E/L

i. . i. L L.

M. aenaeus L. L. L L L L L L L M octodecemspinosus L. L. L L L L L L.

L L E/L M. scorpius L L. L L L L L L Aspidophoroides monopterygius L L L L L Cyclopterus lumpus L L E L L L. L L.

Liparis spp. L L L L L L L L L L L L L L. L.

L. atlanticus L L L L L L L L 51 r, r - r ." I - r pI"- rp--4 W- r-"P-"r-- F- r-- r- ~ w- El- F

W7--- Ir E7 r_,_. UL -- U- r U_ ' E - -E c2 - _ I _ IL. a* -

Table 4 (continued).

Species 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 L. coheni L L L L L L L L L Centropristisstriata L L L L L L L L L Cynoscion regalis L L L Stenotomuw chrysops L L L E Menticirrhussaxatilis L L Labridae E E E E E E E E E E E E E E E Tautoga onitis L L L L L L L L L L L L L L L Tautogolabrus adspersus L L L L L L L L L L L L L L L Lumpenus lumpretaeformnis L L L L L L L Ulvaria subbifurcata L, L~ L L L L L L L L L L L L L Pholis gunnellus L L L L .L L L L L L L L L L L Cryptacanthodesmaculatus L L L L L L L L L Ammodytes sp. L L L L E/L L L L L L L L L L L Gobiosomaginsburgi L L L L Scomber scombrus E/L E/L EIL E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Peprilustriacanthus E/L E/L E/L E E E/L E/L L E/L E/L L E E/L E/L Etropus microstomus L L E E/L E E Paralichthysdentatus E/L E/L L E/L E P. oblongus 3 E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Scophthalmus aquosus3 E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Glyptocephalus cynoglossus EBL EiL E/L E/L E/L E/L E/L E/L E/L E E/L E/L E/L E/L E/L Hippoglossoidesplatessoides E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L EIL Pleuronectesamericanus E/L E/L L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L EBL P.ferrugineus E/L E/L E/L E/L E/L E/L E/L E/L E/L E E/L E/L E/L E/L EIL P. putnami L E/L Trinectes maculatus E E E E E E E/L Sphoeroides maculatus L Number of Species 4 41 36 43 35 37 35 40 38 37 34 42 37 36 41 40 1J = juvenile.

2Absent August and September; peaks = March-May and November-December.

3Although these eggs were not identified specifically, they were assumed to have occurred as shown based on the occurrence of larvae.

4 For comparative purposes three species of Myoxocephalus were assumed for 1975-1978 and two species of Liparis for 1975-1980.

52

Table 4 (continued).

Species 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Period of Occurrence Anguilla rostrata J J J J J J L L L L Feb- Sep Congeroceanicus L Jul Alosa spp. 1 L May - Jul Brevoortiatyrannus E/L E/L E/L EIL EIL E/L E/L E/L E/L EIL E/L EIL E/L E/L E/L Apr(Jun) - (Oct)Dec Clupeas harengus L L L L L L L L L L L E/L L L L Jan-Dec2 Anchoa spp. L L L L L L L L L L E/L E E/L Jun- Sep A. mitchilli E E E E L E E/L E/L Jun- Sep Osmerus mordax L L L L L L EIL L E L L Mar-Jul Brosme brosme E/L E Apr-Jul Enchelyopus cimbrius E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Apr(Jun) - (Sep)Dec Gadus morhua E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Jan(Nov) - (Dec)Dec Melanogrammus aeglefinus E E E L E/L E/L E/L E E/L E/L Mar - Jul Merluccius bilinearis E/L E/L E/L E/L E/L E/L E/L E/L E/L EIL E/L EIL E/L E/L E May(May) - (Jun)Nov Microgadustomcod L L L L L L L L L L L L L L Jan -Jun Pollachiusvirens L L E/L L L E L I E L Jan-JunNov,Dec Urophycis spp. E/L E/L E/L E/L E/L E/L E/L E/L E EIL E/L IL E/L EIL EIL E/L Apr(Aug) - (Sep)Nov Ophidion marginatum L L L L L Aug - Sep Lophius americanus E/L E/L E/L E/L EIL E/L E/L EIL EIL E/L EIL E/L E/L E E May - Oct Strongylura marina Jul Fundulus spp. Jul F. heteroclitus Jun F. majalis E Oct Menidia spp. L L L L L L L L :L E/L L E/L L L May - Sep M. menidia .E E E/L May - Sep Syngnathusfuscus L L L L L L L L L L L L L L L Apr - Nov Sebastes norvegicus L Jun Prionotusspp. E E E E/L E E E E/L E/L E/L E/L E E/L E/L E May(Jun) - (Aug)Sep Hemitripterusamericanus L L L Feb- Mar Myoxocephalus spp. L E/L L L L L L L L L Dec(Mar) - (Apr)Jul M. aenaeus L E/L L L L L L L L L L L L L L Jan(Mar) - (Apr)Jul M. octodecemspinosus L L L L L L L L L L L L L L L Jan(Mar) - (Apr)May M. scorpius L L L L L L L L L L L L L L L Feb - Apr Aspidophoroidesmonopterygius L Mar - Apr Cyclopterus lumpus E/L E/L L L L L L L Apr- Jul Liparis spp. L L L L L L L L L L L Jan(Apr) - (Jun)Jul L. atlanticus L L L L L L L L L L L L L L L Mar(Apr) -(Jun)Jul Number of Species 4 27 22 25 26 24 26 23 24 27 25 28 23 24 25 22 53 ff r- r- r-- r W -, V- , r"-" r r- r - r F- r- r- r- r-E .EL rrrF r r r r r Table 4 (continued).

Species 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Period of Occurrenc(

L.coheni L L L L L L L L L L L L Jan(Feb)-(Mar)Apr Centropristisstriata L L L L L L L L L L L Jul - Oct Cynoscion regalis'. L E/L L May- Sep Stenotomus chrysops L-. L L L L L L E/L E/L L L E/L L Jun - Oct(Sep)

Menticirrhussaxatilis Jul - Aug Labridae E E E E E E E E E E/L E E/L E E E Mar(May) - (Aug)Nov Tautogaonitis L L L L L L L L L L E/L E/L L E/L E/L May(Jun)-(Aug)Oct Tautogolabrusadspersus L L L L L L L L L L EIL E/L L E/L E/L May(Jun) - (Aug)Oct Lumpenus lumpretaeformis L L L L L Jan - Jun Ulvariasubbifurcata L L L L L L L L L L L L L L L Feb(Apr) - (Jun)Oct Pholisgunnellus L L L L L L L L L L L L L L L Jan(Feb)-(Apr)Jul Cryptacanthodesmaculatus L L L L L L L L L L L L Feb - Apr Ammodytessp. L L L L L L L, L -L L L L L L L Jan(Mar) - (May)Dec Gobiosoma ginsburgi L L L L L L L L Jul- Sep Scomberscombrus E/L E/L E/L E/L E/L E/L EAL EIL EIL E/L E/L E/L E1L E/L E/L Apr(May) - (Jul)Sep Peprflustracanthus L E/L L L E/L L L E/L L E/L E/L May - Oct Etropus microstomus E E E E/L EIL E/L E/L E/L E/L E Jul- Oct Paralichthysdentatus L E/L E E/L L L L E/L E E/L May - Nov P. oblongus3 E/L EL E\L. E\L E/L E/L E/L E/L E/L L EIL E/L L E/L E/L May - Oct Scophthalmus aquosus3 E/L E/L E/L E/L E/L EIL E/L E/L E/L E/L En, E/L E/L EdL E/L Apr(May) - (Sep)Oct Glyptocephalus cynoglossus E/L E/L E/L E/L E/L EIL E/L E/L EIL E/L E EIL E/L Mar(May) - (Jun)Nov Hippoglossoidesplatessoides- EAL EUL E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L Jan(Mar) - (Jun)Nov Pleuronectesamericanus E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L E/L EJL E/L EAL EAL Jan(Apr) - (Jun)Sep P. ferrugineus E/L E/L E/L E/L E/L E/L E/L E/L EIL E/L E/L E/L E/L E/L E/L Feb(Apr) - (May)Nov P. putnami L L Mar-Jun Trinectes maculatus E/L E E/L E E/L May - Sep Sphoeroides maculatus L Jul - Aug Number of Species4 42 34 36 38 39 42 37 37 40 38 41 37 42 43 39 54

D. Ichthlvolankton Entrainment - Specific Estimated numbers of eggs and larvae entrained annually at PNPS were examined in some detail for six species of fish using the equivalent adult (EA) procedure (see Horst 1976, l Goodyear 1978, Saila et al 1997, for example). Numbers potentially lost to impingement were also considered. This review dates back to 1980 so that, with the addition of 2004, 25 years of L analyses are included. The adult equivalent methodology applies estimated survival rates to numbers of eggs and larvae lost to entrainment and numbers of fish lost to impingement to obtain l a number of adult fish which might have entered the local population had entrainment not occurred. The consequences, if any, of the loss can then be considered if the size of the extant l population is known or numbers can be compared with commercial or recreational landings.

Many assumptions are associated with the EA procedure. The fish population is L assumed to be in equilibrium, therefore in her lifetime each female will replace herself plus one male. It is assumed that no eggs or larvae survive entrainment. In assessing potential losses the I assumption is also made that no density-dependent compensation occurs among non-entrained individuals, i.e. the approach assumes that non-entrained individuals do not benefit from reduced L competition as a direct result of lower densities. The later two assumptions result in an overestimation of plant impacts. Survival has been demonstrated for some species of fish eggs at L PNPS such as the labrids (45%; MRI 1978a) and winter flounder (73%, n = 11; MRI 1982) and among larvae at other power plants (0-100% initial survival depending on species and size; L Ecological Analysts 1981). More recently LMS (2001) used induced-flow larval sampling tables to assess initial and latent survival among entrained winter flounder and other species. They L determined that larval flounder mortality was high and statistically similar in both intake and discharge samples. In spite of high natural mortality they reported that survival increased with L increasing larval length and decreasing through-plant temperature change.

Numbers of eggs and larvae entrained were determined using the full-load-flow capacity [

of Pilgrim Station. This value was used even if the station was out of service and less than full capacity was being circulated. In those cases the adult equivalents are overestimated further. L Assuming full-load flow for each year was a particular exaggeration for 1984 and 1987 because L both circulating seawater pumps were shut down from April through August yet sampling 55 L Marine Research, Inc. d

continued using the salt service water system. Estimated numbers entrained for species present during those months often appear low for those two years because there is some indication that estimates of ichthyoplankton entrainment is disproportionately low when only the salt service water pumps were in operation (MRI 1994). Using estimates obtained with only salt service water pumps operating to predict what entrainment would have been with the plant operating at capacity would probably be heavily biased on the low side. During an outage in 1999 extending from May 9 to June 11 sampling also occurred only with salt service water pumps running so a similar, but less extensive, bias resulted.

Since plankton densities are notorious for deviating from a normal distribution but do generally follow the lognormal, geometric mean densities more accurately reflect the true population mean. The geometric mean is always less than the arithmetic mean particularly for data which are skewed to the right such as plankton densities (see Figures 5 and 6). In calculating total entrainment values for the adult equivalent methodology we chose to use the larger arithmetic mean for all sampling dates preceding April 1994 when three replicate samples were taken per sampling occasion to lend additional conservatism to the assessments. Beginning with April 1994 each individual sample density was utilized so that no averaging was necessary.

In summary, four opportunities were chosen to overestimate the impact of PNPS

• All eggs and larvae were assumed killed by plant passage regardless of thermal load.

• No density-dependent survival compensation was assumed to occur.

• PNPS was assumed to operate at full-flow capacity year round.

• Mean entrainment densities were overestimated by the arithmetic mean for sampling dates when three replicates were taken.

The six species selected for review were winter flounder, cunner, Atlantic mackerel, Atlantic menhaden, Atlantic herring, and Atlantic cod. Flounder were chosen because of their commercial and recreational value as well as their importance in PNPS ecology studies. Cunner were selected because they are abundant in entrainment samples and in the local nearshore area potentially subject to thermal effects. Mackerel and menhaden were included because they are abundant among the ichthyoplankton entrained, both eggs and larvae being removed from the 56 Marine Research, Inc.

local population, and they are commercially and recreationally valuable. Atlantic herring and cod are not entrained in great numbers but they are valuable species in New England waters. l Winter Flounder L In 2004 an estimated total of 246,468 eggs and 62,178,004 winter flounder larvae were entrained by PNPS (Table 5). The number of larvae ranked second among the 25 totals recorded over the 1980 - 2004 time series ahead of all past years except 1998. The high ranking in 2004 resulted from high densities over a brief period at the end of May and the beginning of June. The brief period of high abundance is reflected in the annual indices discussed above. Based on monthly mean densities, 2004 ranked 4 hand 7h, respectively. The average number entrained from 1980-2003 excluding 1984, 1987, and 1999 when the main pumps were out of service for a L month or more during the egg and larval flounder season amounted to 4,599,422 eggs and 22,493,023 larvae (s.e. = 4,412,756). Values ranged from 28,600 in 2002 to 32,717,500 in 1985 L for eggs and 5,595,000 in 2000 to 86,850,000 in 1998 for larvae.

The relatively high number entrained in 2004 was consistent with recent trends in the L northern winter flounder stock (see USGen New England, Inc. 2004, for example) and the cold winter that likely promoted production of a strong year class (NUSCO 1988, Buckley et aL 1990, L Keller et al. 1999, Keller and Klein-MacPhee 2000). The 1997 and 1998 year classes appeared to be large ones also based on the PNPS ichthyoplankton results, and subsequent area-swept I surveys completed in 2000 and 2001 suggested that increased numbers of reproductive age fish resulted (see Section III, this volume). These fish would have entered the reproductive age pool in 2000 and would have fully recruited to the adult stock by 2002. While the area-swept estimates dropped in 2003 and again in 2004, these fish would have been six and seven years old L in 2004 and highly fecund.

The annual larval entrainment estimates were converted to equivalent numbers of age 3 L adults, the age at which flounder become sexually mature (Witherell and Burnett 1993, NOAA 1995). Numbers of eggs collected from 1980 - 1994 when 0.333-mm mesh was used on all L sampling occasions were scaled upward by 1.24 to correct for mesh extrusion. While no direct mesh extrusion information is available for winter flounder eggs in the PNPS discharge stream, L 57 [

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the value for similar sized cunner eggs was used. Numbers of stage 1 and 2 larvae collected prior to 1995 were likewise scaled upward by 1.62 to adjust for mesh extrusion (MRI 1995). Three sets of survival values were used. The first set followed NEP (1978) using data from Pearcy (1962) and Saila (1976). Briefly, this consisted of dividing the total number of entrained larvae by 0.09 to estimate the number of eggs which hatched to produce that number of larvae. NEP (1978) did not specifically account for entrained winter flounder eggs. While they are demersal and adhesive, numbers of them are entrained each year. A survival rate of 0.058 for entrained winter flounder eggs was assumed based on Rose et al (1996) and assuming that the entrained eggs were 15 days from hatching. The number of newly hatched eggs derived from the number of eggs entrained was then added to the number of hatched eggs derived from the larvae entrained. The combined number of eggs was then multiplied in succession by 0.004536, an estimate of survival from a newly hatched egg to day 26; 0.2995, survival from day 27 to metamorphosis; 0.03546, survival ofjuveniles from 3 to 12 months; 0.3491, survival from 13 to 24 months; and finally 0.33, survival from 24 to 36 months.

The second approach followed larval stage-specific survival rates (S) derived from Niantic River data (Crecco and Howell 1990) as modified by Gibson (1993). These are as follows:

S (stage 1) = 2.36E-0.

S (stage 2) = 1.08E-01 S (stage 3) = 0.154 S (stage 4) = 0.623 S (age 0) = 0.0730 S (age 1) = 0.250 S (age 2) - 0.477 A survival rate of 0.058 was assumed for winter flounder eggs as indicated for the unstaged approach. In using the stage-specific rates it is recognized that NUSCO employs different morphological stage criteria than those used at PNPS (NUSCO 2001). However a comparison of samples from both studies showed stages to be quite comparable until larvae approach metamorphosis, a size not often collected because these individuals begin to assume a benthic life style.

58 Marine Research, Inc.

The third set of survival values obtained from PG&E (2001) was as follows:

Eggs - 0.75 S (stage 1) 0.1286 S (stage 2) = 0.0328 S (stage 3) = 0.0296 X S (stage 4) = 0.8377 S (age 0) 0.0927 S (age 1) = 0.3291 L

S (age 2) = 0.3654 L Numbers of age 3 fish were converted to weight based on 0.49 pounds per fish. This was derived from the length-weight equation presented in NEFSC (1998) using mean length at age 3 ,

for males (262 mm TL) and females (267 mm TL). Mfean length at age was obtained using the gender specific, north of Cape Cod growth equations provided by Witherell and Burnett (1993). L These relationships gave mean weights of 0.47 and 0.50 pounds for males and females, respectively; these were averaged. L The general, unstaged larval survival values produced an adult equivalent value of 3,834 age 3 fish for 2004. The stage-specific values produced EA totals that were higher at 53,153 and i 32,373 age 3 individuals, respectively. Based on a weight of 0.485 pounds per fish, these values convert to 1,859, 24,663, and 15,701 pounds, respectively and average 14,074 pounds. L Comparable values for 1980 - 2003 ranged from 262 to 5,356 fish (mean = 1,388 fish, 680 pounds) for the general approach, 2,632 to 77,394 (mean = 14,663 fish and, 7,112 pounds) for L the Niantic staged approach and 1,040 to 62,171 (mean = 8,956 fish, 4,343 pounds) for the USGen staged approach (Figure 7, Table 5).

EA totals for 1984, 1987, and 1999 based on full load flow were omitted from the estimated means because both circulating seawater pumps were off for much of the larval winter flounder seasons during maintenance outages. As mentioned above there is strong evidence indicating that estimates of ichthyoplankton entrainment are disproportionately low when the salt:

service water pumps are on but the circulating seawater pumps are not. Based on that, entrainment sampling was not conducted during the portion of the 2001 and 2003 outage periods in which both main seawater pumps were shut down. Based on actual flow rates entrainment l L

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was understandably low during those three years with staged EA values ranging from 53 to 447 and 12 to 141, pounds respectively and unstaged values ranging from 10 to 107 pounds.

The differences between unstaged and staged EA totals clearly show how relatively small variations in survival values when applied to large numbers of larvae can result in relatively large variations in adult numbers (see Vaughan and Saila 1976 for example). The USGen survival rates were greater for eggs and stage 4 larvae than the Niantic based rates therefore years when eggs and or stage 4 larvae were prevalent reflected higher EA values.

In addition to entrainment losses small numbers of winter flounder were impinged on the intake screens each year (Table 6, see also the impingement section). Annual totals ranged from 42 in 1984 to 2,301 in 2001 and averaged 838 fish over the time series. The 2004 estimated total was above average at 1,647. Based on mean length data most impinged fish each year were young-of-the-year. Assuming all fish 'would have completed their first year and applying the average age 1 and age 2 survival rates from the entrainment EA procedures, these totals would be equivalent to an annual average of 99 age 3 adults (range = 5 to 276) weighing 48 pounds (range = 2 to 134 pounds). Although winter flounder typically survive impingement quite well, particularly under continuous screen wash operation (see for example MRI 1982, 1984, 1997), no further adjustment was made to the equivalent adults resulting from impingement.

Over the 1982 through 2003 period an annual average of 1,136,454 pounds (s.e.

248,639 pounds) of flounder were landed commercially from NOAA statistical area 514 which covers Cape Cod Bay and Massachusetts Bay. Based on a weight of 0.485 pounds per fish, the average estimated loss of 4,091 pounds of equivalent adults due to PNPS entrainment and impingement over a similar time frame based on the three sets of survival calculations (720, 7,161, 4,392, Table 5,6) represents 0.4% of those landings. Area 514 commercial landings declined sharply after 1993 from 1,057,211 pounds that year to 16,788 pounds in 1995, 1,798 pounds in 1997, and only 221 pounds in 1999. Catch rebounded in 2000 to 40,000 pounds but dropped again each of the next three years to 4,742 pounds in 2003. The precipitous drop from 1993 to 1999 is attributable to increased fishing restrictions and stock declines. EA values for 1994 through 1998 and 2001 alone appear quite high compared to the reduced commercial 60 MarineResearch, Inc.

f landings and in fact the lower unstaged values for both 1997 and 1998 exceeded the commercial landings for those two years indicating that commercial landings are no longer a realistic L measure of the scale of equivalent adult values for heavily fished and regulated stocks.

Winter flounder also have considerable value as a recreational species. Based on NOAA L records' an annual average of 783,062 fish (s.e. = 246,525) weighing an average of about 0.9L pound each were landed from Massachusetts inland waters and within 3 miles of shore over the 198 1-2003 period. Over the course of the past decade or so (1990-2003) recreational landings were well below 1980's levels because of stock declines and catch limits consistent with commercial landings; an annual average of 113,882 fish (s.e. = 10,433) were reported landed in the state from inland waters and within 3 miles of shore since 1993. These fish were also apparently smaller, weighing an average of 0.6 pounds each. Unfortunately recreational landings are compiled by state within distance from shore areas (inland, <3 miles from shore, > 3 miles from shore) and the number of fish taken from a more appropriate area such as Cape Cod Bay L are not available. Arbitrarily adding 20,000 pounds of recreationally-caught flounder to the depressed 1994-2003 Area 514 commercial landings would bring the respective totals for those L ten years to an average of 63,440 pounds (s.e. = 31,970). The average PNPS EA entrainment and impingement values based on the three parameter sets for the same years (6,434) would [

amount to 10%. Clearly the decline in commercial landings after 1994 considered along with the stick abundance data suggest that those values even when combined with the recreational L landings are no longer a realistic measure of PNPS EA losses.

Massachusetts Division of Marine Fisheries (DMF) personnel made estimates of the I number of adult winter flounder (>280 mm TL - age 3+) in a 106 square mile area in the vicinity of PNPS using area swept by a commercial trawl each year from 1997-1999 (Lawton et al. E 2000). In 1997 and 1998 they also completed estimates of stock size using several mark and recapture models. Marine Research, Inc. completed comparable surveys from 2000 through L 2004 (see section 3.1 of this volume). While reliable estimates of local population size are difficult to make, they can provide more realistic numbers with which to compare EA values L relative to commercial and recreational landings which are difficult if not impossible to pinpoint Recreational landings data were obtained via the internet at http://remora.ssp.nmfs.gov/mrfss.

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to the actual impact area. Landings data typically represent numbers caught over a very large area or as displayed by the most recent commercial landings can be subject to catch restrictions or changes in fishing effort which make them less useful.

The MRI area swept estimate for 2004 equaled 157,532 adults based on gear efficiency of 50% with confidence limits ranging from 154,555 to 160,509 fish. Over the past three years estimates averaged 298,800. The relatively high estimates over the previous three years are consistent with the large numbers of larval flounder entrained in 1997, 1998, and 2004.

Members of the 1997-1998 year classes would have reached ages 6 and 7, respectively in 2004.

Natural and fishing mortality would be expected to reduce their numbers over time consistent with the drop observed in 2003 and 2004. Comparing the age 3 equivalent adults estimated for 1997 through 2001 with the corresponding area-swept estimates provided the following percentages:

Equivalent Age 3 Adults (Number of Fish) Area-Swept Percent Of Area-Swept Estimate Entrainment and Impingement Estimate 3 Years Hence

.t 1997 27,398 464,176 5.9 1998 48,483 400,812 12.1 1999 1,615 476,263 0.3 2000 2,275 262,604 0.9 2001 16,883 157,532 10.7 Note that equivalent adult totals shown are averages of the three sets of survival rates.

The current 2004 estimated equivalent adult loss of 29,214 fish based on the three sets of survival rates amounted to 9.8% of the average area-swept estimate for the previous three years.

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RAMAS Winter Flounder Model, The computer software program entitled RAMAS (Risk Analysis Management Alternative System; Ferson 1993) was used from 1999 - 2001 to further assess the possible, effects of PNPS on the western Cape Cod Bay winter flounder population (MRI 2000, NAI l 2001, MRI 2002). A stage-structured model was developed using an empirically derived Ricker stock-recruitment (s-r) function for winter flounder. Each model run included 50 time steps and L 500 to 750 replications. Results obtained with the RAMAS\Stage model, suggested stock reductions from 2.3 to 5.2% might occur as the direct result of entrainment at PNPS. The model based on mean numbers entrained suggested population reductions of 4.3 or 4.5% depending upon the size of the existing adult population. To simulate one possible future with biannual outage periods during the winter flounder larval period suggested modest population reductions of 2.1 to 3.4% might be expected.

During 2002 RAMAS Metapop (version 4.0, Akcakaya 2002) was used to explore L possible consequences of entrainment. Like RAMAS Stage, Metapop utilizes matrix algebra to simulate changes in population size but, in addition to being MS- Windows based, it is a more versatile program. A model was established to represent a winter flounder population near its carrying capacity. Carrying capacity for adults (K) was defined by the relationship K = L 12387.9366AA0.9440498 where A represents habitat area in square kilometers (ASFMC 1992, LMS 2001). Using the area of western Cape Cod Bay from the winter flounder area-swept study (267.4 kin2 ; see this volume, Section 3.1) a carrying capacity of 1,463,000 adult flounder would be expected from the bottom area relationship. Since Metapop was modeled with females only L and an even sex ratio was assumed the expected virgin population size was 730,300 adult females.

Initial simulations were performed with an unfished population. Entrainment was accounted for using the dispersal feature in Metapop. Three identical populations were simulated, numbers of larvae entrained were "grown" to age 0 using stage-specific mortality rates and these individuals emigrated from population 1 to population 2. Emigration in the L reverse direction was set to zero. Population 3 did not experience emigration or immigration and 63 L Marine Research, Inc.

so represented a virgin stock. Numbers of age 0 fish and numbers of adults (age 3+) were compared between population 1 and 3 to measure the effects of entrainment.

The dispersal rate corresponding to numbers removed from the population as a result of entrainment at PNPS was calculated using the stage-specific survival rates. Each year from 1980 through 2002 numbers of winter flounder eggs and larvae entrained were equated to age 0 juveniles consistent with the first time step in Ramas. The average of these values (48,862 females) along with the observed coefficient of variation (0.26) amounted to 1.9% of the number of age 0 female fish in the model population (2.622 million). This was the dispersal value.

Density dependence was-included in the model using the Beverton and Holt (1957) function. The modeled virgin population responded to the withdrawal of 1.9% of its age 0 individuals with a compensatory increase in vital rates consistent with density dependence. As a result the increase in fecundity and survival produced somewhat more adult fish than the population with no entrainment loss since plant losses affected only age 0 individuals. Multiple model runs with intrinsic rates of increase ranging from 1.0 to 1.6 indicated that a notable decrease in adult stock would not begin as a result of entrainment unless the intrinsic rate of increase was 1.20 or less.

Results suggested that with even small intrinsic rates of increase a winter flounder population can readily compensate for entrainment losses on early life history stages of 2% or more in the absence of fishing.

Model runs completed with varying dispersal rates indicated that a population with density-dependent survival and reproductive rates along with intrinsic rates of increase equal to 1.57 can thrive'with the removal of most of its'age 0 individuals. The adult population does not begin to decline in the absence of fishing until entrainment reaches 0.9. Without density dependence the population steadily declines since there is no biological mechanism to compensate for losses to entrainment or fishing. With density dependence, as the number removed increases, survival and fecundity of the remaining individuals increase to offset the loss.

Model runs were next completed with various levels of fishing effort. A four-population model was used to simultaneously compare a population with dispersal or entrainment maintained at 1.9% (coefficient of variation = 0.26), a population with fishing, a population with 64 Marine Research, Inc.

entrainment and fishing, and a virgin population. To determine the level of fishing mortality necessary to reduce the virgin population to around 240,000 adult females, consistent with area l swept estimates of the local adult population (see Section 3.1). Runs were made with fishing mortality between 10 and 45% (instantaneous fishing mortality F = 0.11 to 0.58). Under fishing, pressure alone an annual harvest rate of 0.43 (F = 0.56) reduced the average number of adults at the end of the simulation to 244,100. With fishing mortality and entrainment the average number of adults at the end of the simulation was 241,700 consistent with the most recent area swept estimate and 1% below the adult population size without entrainment. These runs suggested that the intrinsic rate of increase and fishing mortality have a much more dramatic influence on population size since both act upon all adult age classes while entrainment acts upon only the first month or two of early life. v Ramas metapop was used in 2003 to further explore potential effects of PNPS on local winter flounder. The ability of Ramas to incorporate trends in vital rates was used to examine more closely the role of fishing mortality. Since Ramas cannot incorporate both trends in vital rates and density dependence in the form of Ricker or Beverton and Holt relationships, a simpler D "ceiling" density dependence function was used with a carrying capacity of 3,000,000 total female fish. The model population could therefore grow to a maximum of 370,000 adult [

females. While that was lower than the area-based carrying capacity defined above, population size was consistent with the area-swept estimates obtained by bottom trawl (see Section 3.1). L These rates provided an annual growth rate of 1.25, less than the maximum rate of 1.57 (Rmax) but consistent with a heavily fished stock. A heavily fished stock should have relatively high L natural survival rates because of reduced competition but since the population is not at extremely low levels growth at the maximum rate would not be expected. L Gulf of Maine fishing mortality rates from 1982 to 2002 were incorporated with and without entrainment losses. Fishing mortality rates were available for 1982-2002 (NFSC 2003). '

The simulation began with 1976 and ran for 30 years, a reasonable length of time for a power station. During the first five years no fishing or entrainment mortality was applied so the L population remained around 367,000 adult females. Incorporating actual fishing mortality 65 Marine Research, Inc. (1

beginning with 1982 resulted in a decline in the population particularly since fishing pressure increased rapidly in the mid 1980's and early 1990's.

Entrainment losses were also incorporated based on information obtained from the 2000 and 2002 larval flux studies. Based on the average proportion of winter flounder larvae passing by PNPS that were estimated to be entrained (0.004925, ENSR and MRI 2001, 2003) age 0 survival was reduced by a conservativel% each year or approximately twice the estimated value.

The 1% rate change also overstated entrainment because it was applied to age 0 fish when in fact entrainment only influences flounder during the first three months of their first year (small rates of impingement not withstanding). Entrainment reduced the number of adult females by from less than 1% to 3% depending on the prevailing fishing mortality rate. The greater the losses to fishing the greater the reduction in population size due to entrainment because winter flounder or any fish population has a diminishing ability to compensate for losses to both adults and larvae.

The 2003 and 2004 area swept estimates suggest that the number of adult winter flounder in the survey area has declined recently consistent with stock assessment estimates for the Gulf of Maine (Paul Nitschke, personal communication). The larval flux study completed in 2004 suggested that the proportion of winter flounder drifting based PNPS that was entrained in 2004 was consistent with estimates made in 2000 and 2002 i.e, less than 1%. The most recent stock assessment data indicates that fishing mortality rates are far below peak estimates observed in the 1990's. That raises the question of why the local adult stock appears to be declining at least short term.

There are a great number of variables operating on the"winter flounder stock and it is not possible to pinpoint a single parameter or even a subset of variables to explain the lack of correspondence between the trawl data and the estimates of entrainment and fishing mortality.

Those variables having the largest potential affect would be underestimated fishing mortality (F) and under estimated area-swept trawl efficiency because they influence all age classes. As indicated in Figure 8 using the Ramas model larval entrainment rates as high as 20 and 30%,

equivalent to more than 20 or 30 times the rate suggested by the empirical data have little affect on adult stocks when fishing mortality is low (F = 0.12 to 0.25). Model parameters for the 2004 runs were the same as the ones used in 2003 (MRI 2004) with the exception that age 1 survival 66 MarineResearch, Inc.

was reduced by 5% starting with 2002 to reflect cormorant predation (French-McKay and Rowe 2003). These results suggest that local fishing mortality rates are likely higher than the Gulf of Maine in general consistent with ASMFC (2005).

Cunner As described above, cunner eggs are among the most abundant fish eggs in PNPS L entrainment samples and in the waters surrounding the Station (Scherer 1984). Total numbers entrained ranged from 675,000,000 in 1991 to 6,576,000,000 in 1981 with a time series mean of 2,608,806,000 (s.e. = 331,760,000). For cunner larvae annual totals ranged from 2,792,000 in 1992 (1984 excluded) to 576,300,000 in 1981 with a time series average of 78,331,000 (s.e. =

26,934,000). Totals for 2004 increased relative to 2003 but were relatively low amounting to 1,452,433,000 eggs and 16,759,000 larvae. These values equaled 56% of the times series mean for eggs and 21% of the times series mean for larvae.

Goodyear's (1978) basic procedures were used to estimate equivalent adult values for cunner. This method converts numbers of eggs and larvae to numbers of fish at age of sexual.

maturity which occurs for approximately half the population at age 1 (P. Nitschke, University of Massachusetts, Amherst, personal communication). Assuming all labrid eggs were cunner eggs L in PNPS entrainment samples (Scherer 1984), cunner larva/egg ratios were determined from PNPS samples to provide an estimate of survival from spawned egg to entrained larva. Mesh L correction values were first applied to both eggs and larvae. Presented in MRI (1998) these were 1.24 for eggs taken from 1980-1995, 1.14 for eggs taken in 1995, and 1.10 for eggs taken in L 1997. The mean of 1995 and 1997 values was used for 1998 through 2004 except in early-season cases where cunner eggs occurred in 0.202-mm mesh samples. Larval cunner mesh L values applied were 1.16 for stage 1 and 1.28 for stage 2, irrespective of year. From 1980 to 2004 the larva/egg ratio ranged from 0.001284 to 0.128812 and averaged 0.029184; 1984, 1987, L and 1999 were excluded because of extended circulating seawater pump shutdown during the cunner spawning season. Average lifetime fecundity was calculated from fish collected in the L PNPS area by Nitschke (1997) and Nitschke et al. (2001a, b). He provided numbers of eggs produced at age in the second order form: L 67 1!

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Log F = [2.891 log A] - [1.355 log A2] + 3.149 where F = fecundity at age A Age-specific instantaneous mortality necessary for calculation of average lifetime fecundity was calculated from fish trap collections made from 1992 - 1997 (Brian Kelly, Massachusetts Division Of Marine Fisheries, personal communication, MRI 1998). Average instantaneous mortality rates for the PNPS area collections from 1992 through 1997 using this approach were as follows:

Age 3 = 0.286 Age 7 = 0.653 Age 4 = 0.342 Age 8 = 1.463 Age 5 = 0.645 Age 9 = 0.728 Age 6= 1.260 Utilizing data from Serchuk and Cole (1974) for age 1 through 5 cunner collected with assorted gear, a survival rate of S = 0.605 was obtained (Z = 0.5025) which appears comparable to the PNPS values. Age 1 and 2 fish appeared less abundant in the PNPS collections than age 3 fish (MRI 1998), suggesting they were not fully recruited to the trap collections, perhaps due to their small size or behavior. Fish older than age 10 were rarely taken both because they are uncommon and because they can exceed the maximum size susceptible to the fish traps. In the absence of additional information an overall mean value of Z =0.831 was substituted for age 2 and age 10.

Based on the PNPS area fecundity study (Nitschke 1997, Nitschke et al. 2001), 50% of age 1 females were assumed to be mature; complete recruitment was assumed by age 2.

Following Goodyear (1978), an average lifetime fecundity of 21,656 eggs per female at age 1 was calculated (MRI 1998). Utilizing the survival estimate for eggs to larvae assuming most eggs were recently spawned and average lifetime fecundity, a survival estimate for larvae to adult of 3.084E-3 was obtained. Converting numbers of eggs to larvae utilizing the larva/egg ratio and then converting numbers of larvae to adults produced an estimate of 188,107 cunner potentially lost to entrainment effects in 2004. 'Comparable values for 1980-2003 ranged from 113,960 in 1991 to 2,384,804 adults in 1981 averaging 482,537 (s.e. = 103,699) over the 24-year period (Figure 9, Table 7). The high value of 2,308,039 recorded in 1981, attributable to high egg and exceptionally high larval densities skewed the mean EA value. As mentioned for winter 68 Marine Research, Inc.

flounder, estimates made in 1984 and to a lesser extent those made in1987 and 1999 were biased on the low side apparently due to reduced flow during outage periods. Table 8 presents estimates i for 1984, 1987, and 1999 based on both full-load flow rates and those actually recorded.

Without those three values and without the 1981 extreme a mean of 407,913 (s.e. - 73,997) was obtained.

In addition to numbers of eggs and larvae entrained cunner were impinged on the intake screens (see impingement section). Annual estimated totals ranged from 33 in 1988 to 1,683 in 1980 with a time series average of 295 fish. A total of 206 fish was impinged in 2004 somewhat L below average. Since cunner mature at a young age no equivalent adult adjustment was made to the number impinged. No adjustment was made for impingement survival although numbers of cunner do survive being impinged at PNPS (MRI 1984).

Cunner have no commercial value and little recreational importance (although many may be taken unintentionally by shore fishermen) so that current landing records are not available.

To shed some light on their abundance in the PNPS area, calculations were performed to estimate the number of adult cunner which would be necessary to produce the number of eggs found there. The PNPS area was defined by Cape Cod Bay sampling stations 2,3,4,7,8 (MRI 1978b), the half-tide volume of which was estimated by planimetry from NOAA chart 1208 at L 22,541,000 100 m3 units. Labrid egg densities were obtained at those stations on a weekly basis in 1975 and they were integrated over time (April-December) using the mean density of the five L stations. The integrated values were multiplied by 1.40 to account for extrusion through the 0.505-mm mesh used in that survey (MRI unpublished data), then by the sector volume. Based L on the 0.333/0.202-mm mesh data collected from the PNPS discharge stream from 1994 through 1997, additional upward scaling might be appropriate; however specific data for towed samples with 0.202-mm mesh are not available and an estimated value was not applied. Omitting this step likely led to an underestimate of the number of eggs produced and therefore to an L underestimate of the number of adults spawning in the area. The resulting value was divided by 2.2, the estimated incubation time in days for cunner eggs (Johansen 1925), then divided by L 30,230, an estimate of mean annual fecundity per female derived from Nitschke (1997) and Nitschke et al. (2001); see also MRI (1998). Lastly the resulting value was multiplied by 2 l 69 MarineResearch, Inc.

assuming an even sex ratio. These calculations resulted in an estimated production of 6.899E12 eggs by an estimated 207,473,000 adult fish. The loss of 188,313 adults in 2004 due to PNPS operation represents 0.090/O of the estimated spawning stock. The annual mean loss of 482,832 fish to entrainment and impingement, including all years, represents 0.2% of the stock estimate.

In earlier studies MDMF personnel chose cunner as an indicator species for PNPS impact investigations. Tagging studies were conducted during the 1994 and 1995 seasons to estimate the size of the cunner population in the immediate PNPS area. Minimum tagging size and therefore the minimum size fish enumerated was 90 mm TL. Estimates were highly localized since individual cunner have a very small home range measured on the order of 100 m2 or less (Pottle and Green 1979). Very young cunner may spend their first year within a single square meter (Tupper and Boutilier 1995, 1997). Estimated population size for the outer breakwater and intake areas combined were 7,408 and 9,300 for the two respective years. Combining upper 95%

confidence limits for breakwater and intake produced totals of 10,037 and 11,696 fish, respectively. Since the upper confidence limit total is only 0.003% of the egg based population estimate, it is clear that eggs must arrive at PNPS from areas removed from the immediate vicinity of the Station. A hydrodynamic modeling study completed by Eric Adams of MIT predicted that 90% of the cunner eggs and larvae entrained at PNPS come from within about 5.5 miles of PNPS to the north down to White Horse Beach, about one mile to the south of PNPS.

This area extends further to the north than the area 2,3,4,7,8 used in the above egg estimates and would presumably provide an even greater adult population estimate. The number of eggs entrained indicated that'cunner must be very abundant in these waters.

Atlantic'Mackerel

'Numbers of mackerel eggs entrained at PNPS'ranged from'81,599,000 in 1981 to 4,674,000,000 in 1989 with an average of 996,572,500 (s.e. = 254,943,000; excluding 1984, 1987, and 199). Totals for larval'mackerel ranged from 2,790,400 in 2003 (again 1984, 1987, and 1999 were omitted) to 320,135,596 in 1981 with an average of 49,310,700 (s.e. -

16,643,900). Corresponding values for 2004 were 70,228,000 for eggs and 10,895,000 for larvae based on actual station flow, both well below time series average values.

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i Procedures outlined by Vaughan and Saila (1976) were used to derive a survival rate for spawned mackerel eggs to age 1 fish. This procedure utilizes the Leslie matrix algorithm to estimate early survival from proportion mature, fecundity, and survival within each age class assuming a stable population. Fecundity for Atlantic mackerel was obtained from Griswold and L Silverman (1992) and Neja (1992). Age-specific instantaneous natural mortality (M = 0.20) was obtained from Overholtz et al. (2000) and NOAA (1995). A low fishing mortality rate of F =

0.02 was used consistent with the current low exploitation rate. A maximum age of 14 and maturity schedules were obtained from NFSC (1996). Since two fecundity profiles provide two L egg to age 1 survival values: 2.2772E-6 for Griswold and Silverman, 2.3039E-6 for Neja, values were averaged (2.2906E-6).

To account for the fact that all eggs entrained were not recently spawned and the Vaughan and Saila estimate begins at time of spawning an estimate of daily mortality was derived from Pepin (1991). Based on an average late-spring summer water temperature of 15 C daily mortality was estimated to be M, = 0.074. At 15 C mackerel eggs require approximately 4 days to hatch assuming an average diameter of 1.15 mm (Colton and Marak 1969, Pepin 1991). l Entrained eggs were therefore assumed to average one day old with a corresponding mortality rate of M = 0.446 (survival rate S = 0.640). The number of entrained eggs was therefore divided L by 0.640 to estimate the equivalent number of newly spawned eggs entrained.

To back calculate from entrained larvae to spawned eggs so the spawned egg to age 1 L survival rate could be applied the observed average ratio of eggs to larvae for PNPS of 0.07984 (1980-2004) was used. In calculating larvae/egg ratios 1981, 1984, 1987, and 1999 were L omitted, 1981 because larvae were more abundant then eggs, 1984, 1987, and 1999 because both circulating seawater pumps were off for all or an important portion of the mackerel egg and L larval seasons during maintenance outages. A mesh adjustment factor of 1.12 was applied to the egg data obtained with 0.333-mm mesh nets based on mesh comparison collections completed l from 1994 through 1997 (MRI 1998). No mesh adjustment was justified for larvae. Numbers of entrained larvae were divided by 0.07984 then by the age adjustment factor of 0.640 and the L back calculated total was then added to the age-adjusted egg total. The age 0 survival rate of 2.2906E-6 was then applied to the combined egg total to derive the number of age 1 fish L 71 Marine Research, Inc.

According to NOAA (1995, 1998) and Overholtz (2000) stock biomass consists of fish age 1 and older while fish completely recruit to the spawning stock by age 3. Therefore, juvenile and adult equivalent values are shown for both respective age groups (Figure 10, Table 8). Age 3 individuals were estimated using an instantaneous mortality rate of M = 0.52 for age 1 fish and M = 0.37 for age 2 fish (Overholtz et al. 1988). These values provided annual survival rates of S

= 0.595 and 0.691, respectively. Numbers of age 1 and 3 mackerel were expressed on a weight basis using 0.2 and 0.7 pounds per fish, respectively (Clayton et al. 1978).

PNPS equivalent age 1 juveniles attributable to entrainment for 2004 amounted to 740 age 1 fish weighing 148 pounds or 304 age 3 fish weighing 213 pounds. Corresponding age 1 values over the 1980 through 2003 time series ranged from 808 (1982) to 19,667 (1989) fish with an average of 5,777 (s.e. = 1,185). Age 3 values ranged from 332 to 8,086 with an annual average of 2,375 (s.e. = 487) individuals. Data from 1984, 1987, and 1999 were omitted here because values were unusually low as described above for the larvae/egg ratio calculations.

Converting numbers of fish to weight resulted in an estimated average annual loss through 2003 of 1,155 pounds (s.e. = 237 pounds) or 1,663 pounds (s.e. = 341), respectively (1984, 1987, and 1999 excluded). The number of eggs and larvae entrained in 2004 and therefore the number of equivalent juveniles and equivalent adults was quite low amounting to 11% of the time series mean (Table 9). This follows 2001, 2002, and 2003 when numbers ranged from only about 13 to 23% of the time series average. The below average totals suggest that mackerel egg and larval production in the waters near PNPS were not particularly high during the last four years. The last stock assessment for mackerel was completed in 1999 (Overholtz 2000). At that time stock biomass was believed to be at historic high levels. Whether recent entrainment data reflect a recent downward trend in abundance or a shift in spawning location is unknown at this time.

Atlantic mackerel are swift swimmers and are not often impinged at PNPS. They occurred during only six years from 1980 to 2004 with an average of five individuals annually.

Based on their mean size most were adult fish and therefore included with the EA totals.

According to NOAA statistical records, an annual average of 272,900 pounds (s.e. =

73,265) of mackerel were taken commercially from statistical area 514 over the years 1982-2003. For PNPS the loss of an average of 1,155 pounds of age 1 fish (1980-2003; 1984, 1987, 72 Marine Research, Inc.

and 1999 omitted) amounts to 0.4% of those landings and the loss of an average of 1,666 pounds of age 3 fish, 0.6%. In addition to commercial landings, mackerel have considerable recreational value. For example, over the years 1981-2003 an average of 879,863 fish (s.e. = 124,833) were landed in Massachusetts by fishermen working inland waters and within three miles of shore.

These fish had an average weight of about one pound. Unfortunately these landings are available only by state and therefore the portion attributable to Cape Cod Bay is not known. Arbitrarily adding 200,000, 1 pound fish to the commercial landings brings the harvest total to 472,900 pounds. The mean PNPS age 1 loss estimate amounts to 0.2% of those landings and the mean age 3 equivalent adult total to 0.4% of the landings.'

Calculations performed to estimate the number of adult cunner~which would be necessary to produce the number of eggs found in the PNPS area were also completed for Atlantic mackerel. Mackerel eggs occurred at Cape Cod Bay stations 2, 3, 4, 7, and 8 from early May through early July in 1975. Integration over time using the mean density of the five stations produced an estimate of 1.3529E12 eggs. This total included a mesh correction factor of 1.95 to account for extrusion through 0.505-mm mesh (MRI unpublished data). The resulting value was divided by 4, the estimated incubation time in days for mackerel eggs (Sette 1950), then divided by 319,978, an estimate of mean annual fecundity per female for age 3 fish from Griswold and Silverman (1992) and Neja (1992). Lastly the resulting value was multiplied by 2 assuming an even sex ratio. These calculations resulted in an estimated production of 3.382EI 1 eggs by an L estimated 2,114,052 adult fish. The annual mean loss (1980-2003; 1984, 1987, 1999 omitted) of 2,048 age 3 fish due to PNPS entrainment represents 0.1% of that value. L Atlantic Menhaden t Total numbers of Atlantic menhaden eggs entrained at PNPS dating back to 1980 ranged from 393,000 in 1992 (1984, 1987, and 1999 omitted) to 947,800,000 in 1993, with an overall L average of 74,620,700 (s.e. = 46,859,000). Corresponding totals for menhaden larvae ranged from 512,000 in 1991 (1984, 1987, and 1999 omitted) to 48,300,000 in 1997 averaging L 9,976,467(s.e. = 2,957,894) over the 1980 - 2003 time series. Totals for 2004 amounted to 613,682 eggs and 176,011 larvae 0.8% and 2% of the respective time series means (Table 9). L 73 Marine Research, Inc.

Numbers of eggs and larvae entrained each year at PNPS were converted to numbers of equivalent adults using the Vaughan and Saila (1976) approach. This procedure requires an estimate of the ratio of larvae to eggs plus fecundity and mortality for each age class. To provide an estimate of survival from spawned egg to entrained larva (Se) the ratio of larvae to eggs at PNPS was calculated. In some years more larvae were entrained then eggs so that estimates were not obtained for all cases. Estimates ranging from 0.005 to 0.890 were obtained in 1980, 1982, 1985, 1986,1988-1991,1993, 1994, 1998,and2001-2004. Ageometricmeanof 0.224was obtained over those 16 estimates. In the Mount Hope Bay section of Narragansett Bay from 1973-1991 a geometric mean ratio of 0.066 was obtained providing a second estimate based on extensive data. An average of the two estimates, 0.145 was used to approximate survival from egg to larva. Since Se is defined as survival from spawned egg to entrained larva an adjustment to the average larvae/egg ratio was necessary. To derive this estimate, collected menhaden eggs were estimated to average one day old, one-quarter their incubation period at 15C, assuming that spawning takes place nearby. A 4-day incubation period was obtained from Pepin (1991) who related incubation duration to water temperature and egg diameter. A mean diameter of 1.6 mm was obtained from Colton and Marak (1969). Pepin (1991) also related daily egg mortality to water temperature (I = 0.030e 0.18T)* Assuming an average spring-early summer water temperature of 15C menhaden eggs would experience a daily mortality rate of Me = 0.4464. The mean egg/larvae ratio of 0.145, equivalent to an instantaneous mortality rate of 1.931 was added to 0.4464 to derive the mortality rate from spawned egg to entrained larva of Ze = 2.3774 (Se =

0.093).

The procedure of Vaughan and Saila (1976) using the Leslie matrix algorithm provided an estimate of survival from spawned egg to age i of 5.419E-05. Fecundity for ages 3 through 5 was obtained from Dietrich (1979). All females were assumed to spawn first at age 3 based on Ahrenholz et al. (1987) who reported that all age 2 fish mature by the fourth quarter. Since fall spawning does occur but is uncommon in Cape Cod Bay (Scherer 1984), we assumed initial spawning at age 3. Dietrich's (1979) age 5 fecundity was assumed for ages 6 through 9 as well since direct counts were not available. Instantaneous natural mortality rates (M) were obtained from ASFMC (2004); these were 0.98, 0.56, and 0.55 for ages 1,2, and 3-9, respectively.

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Fishing mortality (F) of 0.14 for age 1 and 0.79 for older individuals was also used (ASFMC 2004). To account for the fact that all eggs entrained were not recently spawned and the Vaughan L and Saila estimate begins at time of spawning the estimate of daily mortality rate for menhaden eggs described above was used. Numbers of entrained larvae were back calculated to spawned L eggs using Se and that total added to the number of entrained eggs.

These parameters provided an estimate of 155 age 1 individuals potentially lost as a result l of egg and larvae entrainment in 2004. Since menhaden enter the fishery at age 2 (Durbin et al.

1983), the annual natural mortality rate of M = 0.98 and F = 0.14 (S = 0.376) was applied to the L age 1 value to arrive at an estimate of 50 age 2 fish potentially lost to the fishery. Based on a wet weight of 0.6 pound for age 2 individuals (ASFMC 2005), this estimate equals 30 pounds.

Corresponding age 2 values for the 1980-2003 time series ranged from 107 pounds in 2000 to 17,063 pounds in 1993 with an average value of 2,375 (s.e. = 853).,

Age 2 natural (M = 0.56) and fishing mortality (F 0.79) rates were then applied to the numbers of age 2 fish to estimate the number of age 3 adults potential lost to the population. For 2004 the estimate was 13 adults. Corresponding age 3 values for the 1980-2003 time series ranged from 46 to 7,371 with an average value of 1,026 (s.e. = 369; Figure 11, Table 9).

In addition to numbers entrained 4,597 young menhaden were estimated to have been L impinged in 2004 (see impingement section). That compares with an average of 11,604 annually from 1980-2003 (s.e. = 6,501) and a range from 0 in 1981 and 1987 to 149,390 in 2003. The L majority of fish were impinged from late summer through autumn. Since menhaden are sensitive to impingement and handling in general (see for example Tatum et al. 1977, MRI 1984) all were L assumed to have died. Assuming conservatively that 50% would have survived to the end of their first year and 32.6% would then survive to age 2 an additional 749 fish might have been lost to the fishery and 194 adults might have been lost to the spawning stock from impingement losses in 2004. This compares with a time series average of 1,891 age 2 and 490 age 3 fish L potentially lost to impingement. Combined potential entrainment and impingement losses totaled 799 age 2 and 207 age 3 fish in 2004 and averaged 5,807 age 2 and 1,505 age 3 fish over L the 1980-2003 time series.

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The Atlantic menhaden resource has supported one of the largest fisheries in the United States since colonial times and is believed to consist of a single population based on tagging studies (Dryfoos et al. 1973; Nicholson 1978, ASMFC 2004). The menhaden fishery has two components, a reduction fishery that produces fishmeal and fish oil and a bait fishery. As bait, menhaden are collected in pound nets, trawls, haul seines, purse seines and gill nets. Obtaining data from the bait fishery is difficult to obtain but the bulk of the landings in New England are used by the lobster fishery. Bait landings along the Atlantic coast averaged approximately 81,364,500 pounds from 1985-2002 and that represented only about 9% of the total landings from 1985 to 1997, 16% since 1998 (ASMFC 2004). The potential loss of an average of 3,484 pounds of menhaden to entrainment and impingement at PNPS would represent a very small portion of the fishery landings.

Numbers of menhaden eggs were re-examined from 1975 when ichthyoplankton sampling was completed through out Cape Cod Bay (see for example Scherer 1984). At that time menhaden eggs were found from' late May into July and again in October. To determine an approximation of the number of menhaden which might have spawned in the Bay that year mean densities were integrated over time. The integrated total was multiplied by 2.0 to adjust for extrusion through the 0.505-mm mesh-used in those studies (MRI unpublished), then divided by 3 an estimate of the incubation period for menhaden eggs. This value was then divided by the mean fecundity for menhaden used in calculation of average lifetime fecundity (493,343 eggs) and assuming an even sex ratio, multiplied by 2 to account for males. The resulting value was then multiplied by the volume of Cape Cod Bay (4.5E10 m3 Collings et al. 1981). This procedure produced an estimate of 3.4 million adults spawning in the Bay at that time. To be conservative' that number was divided in half assuming that eggs were present in only half the volume of Cape Cod Bay. Using this rough approximation and assuming that numbers of menhaden spawning in the Bay in 1975 were similar to current levels the average loss of 1,505 age 3 menhaden (1980-2003, 1984, 1987; 1999 omitted) would amount to 0.04% of the estimated spawning stock in Cape Cod Bay.

MRI completed estimates of the number of menhaden eggs and larvae passing through the Cape Cod Canal during the 1999 spawning season (TRC 2000). Estimates were based on 76 Marine Research, Inc.

ichthyoplankton sampling completed in the Canal near the eastern end as well as a near-canal station in Buzzard's Bay and in Cape Cod Bay. The seasonal total passing through the Canal l amounted to 520 million eggs and 258 million larvae. The number of menhaden eggs and larvae entrained by PNPS in 1999 amounted to 2.8 and 4.6% of those estimates, respectively.

Atlantic Herring Since Atlantic herring spawn demersal, adhesive eggs primarily on offshore banks they are not subject to entrainment at PNPS. Larvae entrainment based on full load circulating water L flow at the station ranged from 468,800 in 1984 to 43,248,000 in 1995 and averaged 6,797,414 (s.e. = 2,248,644) over the 1980-2003 period. For the 2004 season the number entrained was estimated to be 4,722,708 larvae. Since they are relatively large, no mesh adjustment factor was, applied to the estimated values. Larval herring have typically been entrained from autumn to early spring so total numbers entrained in 1987 when no sampling was conducted in April during an outage period and in 1984 when sampling occurred but the circulating water system was shutdown in April may have been underestimated slightly as mentioned earlier (Table 10).,

The Vaughan and Saila procedure was used to derive an estimate of survival from spawned egg to age 1. For this estimate fecundity was obtained from Messieh (1976); age- L specific mortality of M = 0.2 was obtained from NOAA (1998) and NFSC (1998). A maximum age of 11 was assumed following (NFSC 1998) and fishing mortality was set at F = 0.2 L beginning at age 1. These values provided an estimated survival rate of 5.1004E-5 for a spawned herring egg to age 1. To estimate the number of eggs which must have been spawned to produce L the number of larvae entrained, individuals were assumed to average 45 days of age. This was based on their relatively long larval period (see for example Jones et al. 1978, Folkvord et al.

1997) and the fact that spawning occurs on offshore banks. Over that 45-day period larvae were assumed to experience a mortality rate of 5.75% per day. . This value equals the median L summarized from various authors by Dragesund (1970). A mortality rate of 50% was assumed among spawned eggs (Lough et al. 1985). The mortality rate among eggs coupled with a 5.75% L daily mortality rate over 45 days provided a mortality rate of Se = 0.034804 from spawned egg to entrained larva. L 77 1 Marine Research, Inc.

Dividing the number of entrained larvae by the egg to larva mortality rate and multiplying by 5.1004E-5 provided an estimate of 6,922 age 1 herring potentially lost to entrainment effects in 2004; these might have entered the sardine fishery. Based on an annual survival rate of 0.67 (M = 0.20, F = 0.20, see above), 6,922 age 1 fish would produce 3,107 age 3 adults, the age at which 50% of fish recruit to the spawning stock (NOAA 1995, Overholtz 2000). Assuming age 1 (sardines) weigh 0.03 pounds and age 3 adults, 0.4 pounds, 212 pounds of sardines or 1,268 pounds of adults would have been lost due to entrainment in 2004. These values are 58% of the long-term average for age 1 (366 pounds) and age 3 (2,191 pounds) equivalent fish based on the 1980-2003 time series (Figure 12, Table 10).

In addition to numbers entrained an estimated annual total of 137 young herring were impinged in 2004. That compares with an average of 2,239 annually from 1980-2003 (s.e. =

1,967) and a range from 0 in 1984 and 1996 to 41,419 in 1991. Over the time series fish were most often impinged from late winter to spring although a relatively large number were impinged in July 1991. While some adults appeared in the catch from time to time the majority of fish were small, ranging in length from 25 to 75 mm total length. Converting to equivalent age 3 adults using the annual mortality rate given above would add an annual average of 1,005 age 3 fish.

Atlantic herring have long been an important component of the commercial fishery off the northeast coast of the United States (see for example Matthiessen 2004) They were severely overfished by distant-water fleets during the 1960's and 1970's to the point where no larval herring were found on Georges Bank for a decade (Overholtz and Friedland 2002). They have since recovered and are currently abundant on Nantucket Shoals and in the Gulf of Maine-Georges Bank region. Although likely to increase, landings remain low. For example, while 1.1 million pounds were landed from Statistical Area 514 in 1997, none were reported for that area from 1999 through 2003. Based on the most recent assessment (1997; Overholtz 2002a) spawning stock biomass in the northeast was estimated at 1.8 metric tons or 4 billion pounds of adult fish. Based on the recovery status it is likely that subsequent estimates will show similar or greater abundance then in 1997. If spawning stock biomass in the 514 statistical area equals only one percent of the northeast stock, then the 2004 equivalent adult losses to entrainment and 78 Marine Research, Inc.

impingement at PNPS (1,268 pounds) would amount to about 0.003%. The time series average of 2,191 pounds would amount to about 0.006%. L Atlantic Cod Estimated numbers of Atlantic cod eggs entrained at PNPS dating back to 1980 ranged from 1,268,748 in 1993 to 20,388,850 in 1980 averaging 6,062,556 (s.e. = 1,039,155) over the L 24-year time series from 1980-2003. For cod larvae corresponding estimates ranged from 119,436 in 1989 to 4,215,642 in 2001 averaging 1,058,475 (s.e. = 200,264) over the time series. l Corresponding estimates for 2004 amounted to 5,231,113 eggs and 1,550,052 larvae 86 and 146% of the long term mean, respectively (Table 11). Using the Vaughan and Saila procedure L numbers of eggs and larvae were converted to equivalent age 2 fish, the age at which 50% of the stock reaches maturity and the age at which they enter the fishery. To calculate age 0 survival l using the Vaughan and Saila procedure fecundity at age was obtained by averaging values from May (1967) and Kjesbu (1996). A natural mortality rate of M= 0.20 was obtained from NOAA (1998) along with a fishing mortality rate of F = 0.2 beginning at age 2. A maximum age of 6 was assumed based on their high exploitation rate (Serchuk et al 1994). Using these variables an 1 age 0 survival rate of 1.5506E-6 was obtained.

Survival from spawned egg to entrained larva (Se) was estimated by averaging three i values:i v The average larvae/egg ratio obtained at PNPS from 1980-2004 following adjustment for I the average age of entrained eggs; this equaled 0.0900. To derive this estimate, cod eggs were assumed to average 6 days old, half their incubation period at SC. A 12-day X incubation period was obtained from Pepin (1991) who related incubation duration to water temperature and egg diameter. A mean diameter of 1.5 mm was obtained from Colton and Marak (1969). Pepin (1991) also related daily egg mortality to water L temperature. Assuming an average winter water temperature of SC cod eggs would experience a daily mortality rate of Me = 0.074 or 0.443 over six days. The observed L geometric mean egg/larvae ratio at PNPS from 1980-2004 of 0.1402, equivalent to an instantaneous mortality rate of 1.9648 was added to 0.443 to derive the mortality rate L from spawned egg to entrained larva of Ze = 2.4078 (Se = 0.090).

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• The second estimate relied on daily mortality rates given for the closely related pollock by Saila et al (1997; 0.0068). They estimated egg mortality for pollock eggs from spawning to hatch to be Ze = 0.922 and larval mortality at Z = 1.358 per mm of growth.

Assuming cod larvae entrained at PNPS average 6 mm in length and that they hatch at 3 mm (Colton and Marak 1969) they would be expected to experience a mortality rate of Z

= 4.074. Combined these estimates equal 2.4184 = Z corresponding to a survival rate from spawned egg to entrained larva of S = 0.0068.

• The third value (Se = 0.0077) was derived as follows. Larvae entrained at PNPS were assumed to average 10 days old. Eggs were assumed to require 20 days to hatch with a daily mortality rate of 10% per day (Serchuk et al. 1994). Larval mortality from hatch to day 10 was assumed to be 4% per day (Serchuk et al. 1994) providing a survival rate of 0.0077 from spawned egg to entrained larva.

The average of those three values, Se = 0.0348, was used to estimate the number of eggs necessary to yield the number of entrained larvae at PNPS.

Applying the average Se value to the number of larvae entrained each year, adding the result to the number of eggs entrained and applying the value of age 0 survival to the total provided estimated equivalent adult values of 63 age 2 fish in 2004. This compared with the time series mean of 47 (s.e. = 8). Numbers of fish were converted to weight in pounds using an estimate of 2.0 pounds per fish (Bigelow and Schroeder 1953). For 2004 a weight of 126 pounds was obtained which compares with the overall mean of 94 pounds (s.e. = 16 pounds; Figure 13, Table 11).

In addition to the numbers entrained 137 Atlantic cod were estimated to have been impinged on the PNPS intake screens in 2004. That compares with an average of 25 annually from 1980-2003 (s.e. = 7) and a range from zero to 122 in 1991; no cod were impinged during 12 years (see impingement section). Based on size the majority of impinged cod were young fish ranging in size from 50 to 100 mm total length. Assuming most were age 1 fish the number impinged would account for an additional 112 equivalent adults in 2004 and an average of 20 additional adults over the 1980-2003 time series.

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These totals were considered low relative to any recent landings information for the Cape Cod Bay area. For reference Area 514 landings averaged 41,339 pounds (s.e. = 13,742) over the L past nine years and Massachusetts inland and near shore (< 3 miles) recreational landings averaged 535,409 pounds (s.e. = 212,670) over the same period.

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Winter Flounder PNPS Equivalent Adult Summary 1980 : - , - I 1982 Age 3 Fish 1984 1986 1988 1990 1992 '

1994 s 1996 1998 2000 g',-,f 2002 2004 _

0 10 20 30 40 50 Numbers Of Fish (Thousands)

Annual Mean - 7,636 Figure 7. Numbers of equivalent adult winter flounder estimated to have been lost to entrainment at PNPS, 1980-2004.

Winter Flounder Assessment C

r~.

a 4 6 sr I

E iz

-a-Trawl Estimate 1% PNPS 20% PNPS

- 30°/. PNPS Is 0% PNPS -4* Fishing Rate I Figure 8. Population size estimated by a Ramas modelmwith and without PNPS entrainment, fishing mortality rates, and population size estimated by bottom trawl in western Cape Cod Bay.

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,6 Cunner 'I PNPS Equivalent Adult Summary 1980 1982 _

1984 Age I 1986 1988 _

l, 1990 _

11992 .

1996 1998 2000 2002 B

'; , l' 0 500 1000 1500 2000 2500 Numbers Of Fish (Thousands)

Annual Mean = 486,572 Figure 9. Numbers of equivalent adult cunner estimated to have been lost to entrainment at PNPS, 1980-2004.

Atlantic Mackerel I PNPS Equivalent Adult Summary-1980

.1984 I 1 L

1986 1988 1990 1992 1994 1996 1998 L

2000 2002 2004 0 5 10 15 20 L

Numbers Of Fish (Thousands)

Annual Mean= 4,379 Age I or 1,800 Age 3 Figure 10. -Numbers of equivalent adult Atlantic mackerel estimated to have been lost to entrainment at PNPS, 1980-2004.

83 Marine Research, Inc.

Atlantic Menhaden PNPS Equivalent Adult Summary 1980 _ .

1982 - Age 3 Fish 1984 X ,

1986 , ,

1988 1990

• 1992 1994 ; -

1996 '

I 1998 I 2000 _

2002 2004 0 2 4 6 8 Numbers Of Fish Cl(housands)

Annual Mean - 1,437 Figure 11. Numbers of equivalent adult Adantic menhaden estimated to have been lost to entrainment at PNPS, 1980-2004.

Atlantic Herring PNPS Equivalent Adult Summary 1980 I

1982 Age 33FFish 1984 1986 I 1988 1990 1992 1994 I, 1996 1998 m 2000 - , .

2002 2004 I 0 5 10 15 20 25 30 Numbers Of Fish (Thousands)

Annual Mean - 5,260 Figure 12. Numbers of equivalent adult Atlantic herring estimated to have been lost to entrainment at PNPS, 1980-2004.

84 Marine Research, Inc.

Figure 13. Numbers of equivalent adult Atlantic cod estimated to have been I

Atlantic Cod PNPS Equivalent Adult Summuary 1980 - r 1982 I I :Age 2 Fish 1984 _ X 1986 1988 1990 1992 1994 1996 - .

1998 2000

____ ___ ___ ___ ___ l 2002 -

2004 0 50 100 150 200 250 Numbers Of Fish Annual Mean -67 Figure 13. Numbers of equivalent adult Atlantic cod estimated to have been L

lost to entrainment at PNPS, 1980-2004.

L l

85 l~

MarineResearch, Inc.

l

-' Ur 11 r r , r' _ M-_ EL Table 5. Numbers of winter flounder eggs and larvae entrained at PNPS annually by stage, 1980 - 2004. Numbers and weight of equivalent age 3 adults calculated by three methods is also shown. Estimates based on full-load flow except where indicated.

Number Number Of Larvae Entrained Equivalent Age 3Adults Of Stage Year Eggs 1 2 3 4 Total General Staged Suite I Staged Suite 2 Average Entrained Number Pounds Number Pounds Number Pounds Number Pounds 1980 3,513,717 8,694,456 12,714,822 7,317,129 0 28,726,407 1,773 860 7,448 3,612 2,151 1,043 3,791 1,838 1981 9,674,954 7,606,942 19,133,121 3,073,126 43,304 29,856,494 1,844 894 4,701 2,280 1,445 701 2,663 1,292 1982 7,001,776 2,706,834 6,724,795 11,583,134 425,011 21,439,774 1,324 642 12,652 6,136 7,241 3,512 7,072 3,430 1983 1,305,735 1,933,453 2,246,172 7,558,534 260,350 11,998,508 740 359 7,970 3,865 4,544 2,204 4,418 2,143 1984 341,424 248,082 0 7,570,145 516,247 8,334,475 514 249 9,128 4,427 6,914 3,353 5,519 2,677 1985 32,717,535 1,039,001 2,312,789 8,025,452 130,786 11,508,028 720 349 7,683 3,726 3,490 1,693 3,964 1,923 1986 5,118,035 5,397,403 5,783,669 3,963,747 77,005 15,221,823 940 456 4,371 2,120 1,878 911 2,396 1,162 1987 20,857,334 0 437,608 3,088,405 0 3,526,013 224 109 2,644 1,282 876 425 1,248 605 1988 3,494,771 1,995,968 1,656,376 15,079,960 511,009 19,243,314 1,188 576 15,562 7,548 8,961 4,346 8,570 4,157 1989 6,423,987 1,668,823 5,755,240 2,224,675 39,114 9,687,851 599 291 2,632 1,277 1,040 504 1,424 691 1990 48,501 643,683 1,155,404 6,846,718 33,002 8,678,807 535 260 6,016 2,918 2,212 1,073 2,921 1,417 1991 1,217,178 3,471,022 3,908,488 5.188,056 37,717 12,605,283 778 377 4,967 2,409 1,827 886 2,524 1,224 1992 4,124,308 873,660 876,914 7,034,690 26,192 8,811,456 545 264 6,119 2,968 2,202 1,068 2,955 1,433 1993 3,078,941 1,595,700 3,540,750 4,934,952 88,617 10,160,019 627 304 4,962 2,407 2,228 1,081 2,606 1,264 1994 2,530,707 1,034,617 6,433,716 13,060,373 172,606 20,701,312 1,277 620 12,450 6,038 5,284 2,563 6,337 3,073 1995 2,766,716 1,632,907 2,820,023 8,826,496 375,857 13,655,283 843 409 9,703 4,706 5,979 2,900 5,508 2,672 1996 4,896,687 504,810 5,818,499 11,329,855 995,127 18,648,292 1,151 558 15,401 7,469 12,482 6,054 9,678 4,694 1997 3,609,393 2,225,634 9,537,788 41,484,016 2,126,280 55,373,718 3,416 1,657 47,091 22,839 31,415 15,236 27,307 13,244 1998 1,035,001 3,111,891 20,282,772 58,546,916 4,904,482 86,846,061 5,356 2,597 77,394 37,536 62,171 30,153 48,307 23,429 1999 1,409,453 2,031,988 588,974 1,936,648 123,103 4,680,713 289 140 2,383 1,156 1,694 822 1,455 706 2000 1,693,672 33,482 170,475 5,391,088 0 5,595,045 346 168 4,521 2,193 1,493 724 2,120 1,028 2001 330,283 4,638,546 13,093,697 37,019,304 263,144 55,014,691 3,393 1,645 33,626 16,309 12,814 6,215 16,611 8,056 2002 28,637 1,389,319 6,911,151 14,802,848 1,232,865 24,336,183 1,501 728 19,703 9,556 15,669 7,599 12,291 5,961 2003 1,977,333 722,030 480,190 2,966,524 76,394 4,245,138 262 127 2,951 1,431 1,540 747 1,584 768 Mean 4,966,503 2,300,010 5,515,976 12,035,533 519,092 20,370,612 1,258 610 13,420 6,509 8,231 3,992 7,636 3,704 s.C. 1,498,148 460,591 1,171,783 2,842,935 215,744 4,026,136 248 120 3,501 1,698 2,727 1,323 2,141 1,038 Minimum 28,637 0 0 1,936,648 0 3,526,013 224 109 2,383 1,156 876 425 1,248 605 Maximum 32,717,535 8,694,456 20,282,772 58,546,916 4,904,482 86,846,061 5,356 2,597 77,394 37,536 62,171 30,153 48,307 23,429 1984,1987,1999 Omitted Mean 4,599,422 2,520,009 6,255,088 13,155,123 562,803 22,493,023 1,388 673 14,663 7,112 8,956 4,343 8,336 4,043 s.e. 1,503,601 503,594 1,259,228 3,174,721 245,079 4,412,756 272 132 3,927 1,905 3,085 1,496 2,409 1,168 2004 246,468 159,859 10,431,901 49,597,823 1,988,421 62,178,004 3,834 1,859 50,851 24,663 32,373 15,701 29,019 14,074 Plant outage years recalculated with actual circulating waterflow.

1984 341,424 166,925 0 164,036 15,729 346,690 21 10 226 11 193 94 45 22 1987 20,782,324 0 5,613 23,555 0 3,534,685 218 107 109 53 25 12 6 3 1999 1,409,453 2,030,743 496,056 977,373 1,345 3,505,517 216 106 912 447 291 141 68 33 Notes: Mesh factor -1.24 applied to eggs prior to1995. Mesh factor - 1.62 applied to StagesI and 2 prior to 1995.

Larval densites recorded in 1984,1987, and 1999 are believed to be low relative to densities in surrounding waters. See text for details.

86

Table 6. Numbers of winter flounder impinged at PNPS annually, 1980 - 2004.

Number and weight of equivalent age 3 adults calculated by two methods is also shown.

Estimated Annual Equivalent Adults L Number General Staged Impinged Number Pounds Number Pounds 1980 218 25 12 26 13 1981 229 26 13 27 13 L 1982 344 40 19 41 20 1983 1984 1985 230 42 735 26 5

85 13 2

41 28 5

88 13 43 2 L 1986 653 75 36 78 '38 1987 166 19 9 20 10 1988 184 21 10 22 11 1989 595 69 33 71 35 1990 295 34 16 35 17 1991 1,171 135 65 140 68 -

1992 817 94 46 98 48 1993 1994 1995 1,171 1,069 1,326 135 123 153 65 60 74 140 128 159 68 62 77 L

1996 866 100 48 104 51 1997 770 89 43 92 45 1998 1,493 172 83 179 87 1999 1,353 156 76 162 79 2000 1,313 151 73 157 .77 2001 2,301 265 129 276 134 L 2002 1,347 155 75 161 79 2003 1,435 165 80 172 84 Mean 838 97 47 100 49 L

s.e. 116 13 7 14 7 Min 42 5 2 5 2 Max 2,301 265 129 276 134 2004 1647 190 92 197 96 Values shown for the staged survival suite are the average of both parameter sets.) They did not differ by more than one fish. 'I l.

87

Table 7. Numbers of cunner eggs and larvae entrained at PNPS annually, 1980 - 2004. Numbers and equivalent adults are also shown. Estimates based on full-load flow except where indicated.

Cunner Eggs Larvae . Equivalent Adults Entrainment Impingement Combined Stage I Stage 2 Stage 3 Total Number Number Pounds 1980 3,257,891,776 76,282,260 40,480,032 4,229,248 120,991,540 674,056 1,683 81,089 1981 6,576,294,915 316,245,739 256,567,950 3,508,876 576,322,566 2,384,804 839 286,277 1982 2,010,779,150 6,351,445 3,187,760 597,356 10,136,561 216,988 803 26,135 1983 5,895,329,347 10,961,646 27,571,530 3,955,802 42,488,978 675,563 184 81,090 1984 1,766,764,864 0 176,682 1,029,352 1,206,034 166,908 50 20,035 1985 2,021,886,071 17,182,039 20,392,615 2,307,617 39,882,271 309,750 509 37,231 1986 1,493,653,289 4,419,092 22,197,318 297,368 26,913,778 220,965 224 26,543 1987 4,465,564,080 40,247,222 314,474 248,738 40,810,434 538,325 233 64,627 1988 1,539,089,318 2,290,972 2,624,077 2,461,452 7,376,502 164,908 33 19,793 1989 4,469,416,004 34,100,052 15,224,141 2,863,938 52,188,130 573,769 241 68,881 1990 1,336,048,112 65,705,970 62,378,298 44,014,528 172,098,797 654,158 210 78,524 1991 675,000,390 5,790,172 3,701,490 7,243,966 16,735,627 113,960 402 13,723 1992 2,174,661,078 0 1,186,819 1,605,055 2,791,875 209,474 34 25,141 1993 3,235,317,207 148,674 7,178,133 7,923,303 15,250,109 345,864 104 41,516 1994 1,558,253,667 0 5,545,977 4,440,095 9,986,072 174,726 83 20,977 1995 4,116,491,874 7,961,638 29,910,748 9,257,792 47,130,178 525,573 288 63,103 1996 2,807,124,109 3,765,455 8,094,509 5,558,849 17,418,813 313,002 211 37,586 1997 1,718,289,720 6,444,923 51,895,511 41,294,559 99,634,994 465,986 39 55,923 1998 4,341,664,826 104,908,332 211,248,501 54,060,618 370,217,451 1,542,772 76 185,142 1999 1,717,578,656 36,934,878 11,960,388 7,510,427 56,405,693 332,601 117 39,926 2000 1,349,685,330 22,411,361 39,293,994 1,388,620 63,093,975 319,247 '294 38,345 2001 2,744,377,803 1,044,260 34,542,919 35,707,859 71,295,038 473,361 143 56,820 2002 580,954,607 537,068 4,771,751 10,257,985 15,566,804 101,668 53 12,207 2003 759,226,058 352,721 1,783,511 1,865,231 4,001,463 82,467 221 9,923 Mean 2,608,805,927 31,836,913 35,926,214 10,567,860 78,330,987 482,537 295 57,940 s.e. 331,759,579 13,600,872 13,020,383 3,198,732 26,934,282 103,699 75 12,447 1981, 1984, 1987, 1999 Omitted.

Mean 2,404,256,987 18,532,904 29,660,482 12,066,562 60,259,948 407,913 292 48,985 s.e. 321,292,270 6,603,902 10,386,253 3,750,942 19,062,766 73,997 84 8,880 2004 1,452,433,321 462,728 7,927,232 8,369,181 16,759,141 188,107 206 22,598 Outage years recalculated with actual circulating water flow.

1984 56,209,029 0 33,596 10,105 43,701 5,324 50 639 1987 1,122,803,794 118,232 119,740 1,868 239,840 104,423 233 12,531 1999 1,098,618,436 30,161,622 8,878,633 7,510,427 46,550,682 242,511 117 29,101 Notes: -

Mesh adjustment factors incorporated as necessary.

Egg and larval densities recorded in 1984, 1987, and 1999 are believed to be low relative to densities in surrounding waters.

Applying full load flow values to those densities likely underestimates the numbers which would have been entrained.

1981 omitted from second block because entrainment was unusually high.

Weight based on 0.12 pound per fish.

See text for details.

88

J, i

Table 8. Numbers of Atlantic mackerel eggs and larvae entrained at PNPS annually, 1980 - 2004.

Numbers of equivalent age 1 and age 3 fish are also shown. Estimates based on fuill-load flow.

Equivalent Juveniles, Equivalent Adults L

Total Number Entrained Age I Age 3 Year Eggs Larvae Entrainment Entrainment Impingement Total Number Pounds - Number, Pounds 1980 81,599,432 22,293.108 1,291; 258 531 0 372 1981 1982 1983 183,959,791 108,234,931 186621 320,135,596 9,388,143 41,333,673 15,009 .

808 2,385 .

3,002 162 477 .

6,171 332 981.

46.

0 11 4,352 232 694 L

1984 1985 1986 1987 22,486,619

.1,867,648,438 219,488,066

.71,222,294 78,315 45,711,343 58,33,520 215,561 84 .

8,734 3,401

.265 17

.1,747 680 53 35 .0 3,591 1,398 109 0

0 0-25 2,514 979 76 fC 1988 2,663,608,568 3,401,4890 9,686 1,937 .,3,982 17 2,799 1989 4,673,915,938 65,562,469 19,667 3,933 8,086 14 5,670 1990 .2,313,416,455 4,627,282 . ,487. 1,697 3,490 10 2,450 1991 479,761,865 66,009,482 .4,676 . 935 1,923 '0. 1,346 1992 .377,610,764 8,086,393 1,714 343 705 0 494 1993 1,801,378,418 8,325,789 6,820 1,364 2,804 . 0 1,963 1994 520,917,221 3,419,299 2,018 404 830, 12 589 1995 1,,767,609,278 .197,689,693 ,15,188 3,038 .6,245 .0 4,372 1996 1,507,370,682 70,947,053 8,575 1,715 3,526 0 2,468 1997 316,969,390 25,778,062 2,290 458 942 0 659 1998 530,017,006 56,622,648 4,435 .. 887 1,824 0 1,277 1999 34,498,141 483,595 145 29 .60 . 042 2000 619,863,003 16,496,664 2,958 592 1260 851 2001 150,613,190 4,868,686, 756 151 311 0 218 2002 280,852,511 3,704,444 1,171 234 482 0 337 2003 314,571,725 2,790,425 1,251 250 514 0360 Mean 877,342,931 43,179,280 5,076 1,015 2,087 5 1,464 S.. 231,910,160 14,906,955, 1,104 221 454 , 2 318 L

Mean S.C.

996,572,538 254,943,108 49,310,727 16,643,887 5,777 1,185 1,155 237 2,375 487 5

2 1,666 342 L

2004 70,227,928 10,894,804 740 148 304 0 213 L

Outage years recalculated with actual circulating water flow.

1984 . 570,854 2,480 2 0 . 1 0 1 1987 2,397,224 107,727 12 2 5 0 4 1999 6,182,166 311,394 31 6 13 0 9 2001 134,385,477 4,839,176 698 140 287 0 201 Notes: .

Egg and larval densities recorded in198.4, 1987, and 1999 are believed tobe low relative todensities in L

surrounding waters. Applying full load flow values to those densities likely underestimates the numbers which would have been entrained.

See text for details.

L 89 L

Table 9. Numbers of Atlantic menhaden eggs and larvae entrained at PNPS annually, 1980-2004.

Numbers of equivalent age 2 and 3 fish are also shown including impingement losses.

Estimates based on full-load flow.

equivalent Adults

.Age A e22 Age 3 Year Total Number Entrained Entrainment Impingement Entrainment Impingement Number Number Weight Number Number Eggs Larvae of Fish of Fish (Ibs) of Fish of Fish 1980 16,468,408 12,060,791 2,748 47 1,677 712 12 1981 3,473,080 40,076,799 7,716 0 4,630 2,000 0 1982 365,091,471 1,845,849 10,439 31 6,282 2,706 8 1983 869,580 1,227,190 257 62 191 67 16 1984 4,751,607 0 131 3 80 34 1 1985 41,131,470 9,190,654 2,884 233 1,870 748 61 1986 21,112,802 3,654,854 1,278 158 862 331 41 1987 311,687 1,560,529 305 0 183 79 0 1988 9,273,771 2,713,857 772 11 470 200 3 1989 11,212,165 4,411,807 1,149 189 803 298 49 1990 7,057,041 3,263,718 816 536 811 211 139 1991 5,744,115 512,319 256 322 347 66 83 1992 392,533 1,117,881 223 4 136 58 1 1993 947,815,345 11,833,443 28,439 8 17,069 7,371 2 1994 10,221,752 2,361,834 732 10 445 190 2 1995 3,280,481 12,419,886 2,452 171 1,574 636 44 1996 4,861,265 8,660,874 1,781 258 1,224 462 67 1997 48,899,715 48,283,152 10,531 176 6,424 2,730 46 1998 44,730,447 33,280,806 7,564 161 4,635 1,961 42 1999 14,395,648 19,324,314 4,072 6,582 6,393 1,055 1,706 2000 882,086 809,127 178 6,255 3,860 46 1,621 2001 4,025,648 1,251,898 349 405 453 91 105 2002 14,464,446 5,164,308 1,382 5,421 4,082 358 1,405 2003 6,027,864 5,364,766 1,187 24,351 15,322 308 6,312 Mean 66,103,934 9,599,611 3,652 1,891 3,326 947 490 s.c. 41,145,547 2,667,901 1,259 1,060 923 326 275 1984, 1987, 1999 Omitted.

Mean 74,620,737 9,976,467 3,959 1,848 3,484 1,026 479 s.C. 46,859,009 2,957,894 1,422 1,186 1,023 369 307 2004 613,682 176,011 50 749 479 13 194 Plant outage years recalculated with actual circulating water flow.

1984 300,943 0 8 3 7 2 1 1987 135,755 731,741 143 0. 86 37 0 1999 10,385,304 18,939,526 3,888 6,582 6,282 1,008 1,706 Notes:

Egg and larval densities recorded in 1984, 1987, and 1999 are believed to be low relative to densities in surrounding waters. Applying full load flow values to those densities likely underestimates the numbers which would have been entrained.

Weight conversion based on 0.5 pound per fish.

See text for details.

90

I~

Table 10. Numbers of Atlantic herring larvae entrained at PNPS annually 1980-2004.

Numbers of equivalent age I and 3 fish are also shown.

Total Number Equivalent Juveniles\Adults Number Of Fish Year Larvae Entrainment Impingement Combined Weight(lbs)

Entrained Age I Age 3 Age I Age 3 1980 1,068,466 1,566 116 755 50 302 1981 2,471,492 3,622 30 1,640 110 656 1982 732,857 1,074 115 534 36 214 1983 5,880,315 8,618 23 3,879 259 1,552 1984 468,840 687 0 308 21 123 1985 1986 1987 1,580,435 1,811 ,101 5,142,045 2,316 2,654 7,536 38 3,760 17 1,057-2,879 3,391 71 192 227 423 1,152 1,356 L

1988 1989 1990 639,089 911,487 2,079,483 937 1,336 3,048 33 227 333 435 702 1,518 29 47 101 174 281 607 L

1991 1,280,273 1,876 41,419 19,435 1,299 7,774 1992 3,970,208 5,819 34 2,627 176 1,051 1993 2,098,952 3,076 130 1,439 96 576 1994 16,351,765 23,966 36 10,774 720 4,310 1995 43,247,883 L

63,385 144 28,518 1,906 11,407 1996 9,265,826 13,580 0 6,096 407 2,438 1997 24,445,056 35,827 19 16,091 1,075 6,436 1998 4,026,783 5,902 107 2,697 180 1,079 1999 2000 2001 11,379,446 12,306,502 4,062,977 16,678 18,035 5,955 70 52 61 7,518 8,120 2,701 502 543 180 3,007 3,248 1,080 I

2002 2003 3,468,890 1,045,853 5,084 1,533 319 25 2,425 699 162 47 970 280 L Mean s.e.

6,655,668 1,990,463 9,755 2,917 1,963 1,722 5,260 1,433 352 96 2,104 573 L 1984,1987, and 1999 Omitted Mean s.e.

6,797,414 2,248,644 9,962 3,296 2,239 1,967 5,477 1,618 366 108 2,191 647 L

2,004 4,722,708 6,922 137 3,169 212 1,268 L

Notes:

Outage periods in 1984 and 1987 may have affected entrainment estimates at the end L

of the spring larval herring period.

The outage in 1999 occurred after the larval herring season.

Separate averages are shown for consistency with the other species analyzed.

Weight conversion based on 0.03 for age 1, 0.4 pound per age 3 fish.

See text for details. L 91 L

Table 11. Numbers of Atlantic cod eggs and larvae entrained at PNPS annually, 1980-2004.

Numbers of equivalent age 2 fish are also shown.

Total Number Entrained Equivalent Adults Number Of Fish Combined Year Entrainment Impingement Weight (Ibs)

Eggs Larvae Age 2 Age 2 Age 2 1980 20,388,850 1,450,522 79 12 183 1981 11,620,588 2,173,076 95 100 389 1982 2,582,984 222,721 11 11 44 1983 9,349,728 142,136 17 0 34 1984 11,726,579 587,054 36 0 73 1985 5,071,151 1,441,442 59 0 119 1986 2,788,767 1,035,987 42 21 126 1987 5,623,282 122,579 12 0 23 1988 2,747,034 254,239 13 0 26 1989 3,395,726 119,436 9 0 17 1990 2,406,536 1,566,291 61 0 121 1991 3,668,649 239,746 13 29 84 1992 2,819,673 469,713 21 9 60 1993 1,268,748 446,489 18 43 121 1994 3,119,312 1,904,519 74 0 148 1995 2,549,370 602,594 25 59 169 1996 8,542,922 2,369,255 98 0 196 1997 1,800,711 1,101,118 43 0 86 1998 4,971,621 735,301 33 62 191 1999 1,932,894 464,125 20 38 116 2000 18,525,824 325,095 35 0 71 2001 6,869,977 4,215,642 164 66 460 2002 4,698,000 1,299,393 54 0 108 2003 7,032,420 2,114,930 88 40 256 Mean 6,062,556 1,058,475 47 20 134 s.e. 1,039,155 200,264 8 6 22 Min 1,268,748 119,436 9 0 17 Max 20,388,850 4,215,642 164 100 460 2004 5,231,113 1,550,052 63 112 350 Notes:

Weight conversion based on 2.0 pounds per fish.

See text for details.

92

Lobster Larvae Entrained Nine lobster larvae were found in the entrainment samples collected during 2004. This L represents the second highest number of lobster larvae collected in a single year, the record number collected of 16 occurred in 2003. Previously, only 37 larvae were collected at PNPS in total dating L back to 1974 including more intensive sampling directed specifically toward lobster larvae in 1976.

No direct relationship between prevailing winds or tide at the time of sampling and the number of entrained larval lobster is apparent. However, since night sampling was added to the protocol in 1995, 91% of the lobster larvae captured were collected during the Friday evening sampling period.

That represents 67% of the total larvae captured over the 30-year time period. The addition of a nighttime sample period has likely contributed to the increase in the observed number of lobster larvae entrained since adult female lobsters release larvae at night (Ennis 1975, Charmantier et al. 1991).

Additionally, Pilgrim Station established a protection zone around the plant extending seaward from the shorefront for a distance of approximately 1000 feet on September 11, 2001. Within this zone no lobster harvesting is permitted; as a result there may be an increase in nearshore lobster reproductive activity and successful larvae release.

Following is a tabulation of previous collections:

2004:9 larvae: 2 stage 1, June 4; 2 stage 1, June 11; 1 stage 1, July 5; 1 stage 1, July 23; 1 stage 1, L August 13; 1 stage 3, September 3; 1 stage 4, September 3.

2003: 16 larvae: 1 stage 2, June 2; 1 stage 3, June 6; 1 stage 3, June 13; 7 stage 3, June 20; 5 stage 3, July 4; 1 stage 1, July 11.

2002: none found l 2001: none found.

2000: none found. L 1999: 8 larvae: 4 stage 1, June 18; 1 stage 1, July 3; 1 stage 1, July 5; 1 stage 1, August 6, 1 stage 4, 26 August.

93 MarineResearch, Inc.

L

Lobster Larvae (continued).

1996 - 1998: none found.

1995: 1 larva - stage 4-5, July 28.

1994: none found.

1993: 1 larva -stage 4-5, July 21.

1991-1992: none found.

1990: 2 larvae - 1 stage 1, June 26; 1 stage 4, August 23.

1983-1989: none found.

1982: 1 larva - stage 1 on June 14.

1981: 1 larva - stage 4 on June 29.

1980: none found.

1979: 1 larva - stage 1 on July 14.

1978: none found.

1977: 3 larvae- Istage 1, June 10; 2 stage 1, June 17.

1976: 2 larvae - 1 stage 1, July 22; July 22; 1 stage 4-5, August 5.

1975: 1 larva - stage 1, date unknown.

1974: none found.

94 MarineResearch, Inc.

SECTION V LITERATURE CITED Akcakaya, H.R. 2002. RAMAS GIS. Linking Spatial Data with Population Viability Analysis. Applied Biomathematics, Setauket, New York. 203p.

Ahrenholz, D.W., W.R Nelson, and S.P. Eperly. 1987. Population and fishery characteristics of Atlantic menhaden, Brevoortia tyrannus. Fishery Bulletin U.S. 85(3):569-600.

Anthony, V. and G. Waring. 1980. The assessment and management of the GeorgesL Bank herring fishery. Rapp. P.-V. Reun. Cons. Int. Explor. Mer. 177:72-111.

ASMFC (Atlantic States Marine Fisheries Commission). 2005. ASMFC approves, winter flounder amendment I. Fisheries Focus.14 (2).

Beverton, RJ.H. and S.J. Holt. 1957. On the dynamics of exploited fish populations.

Great Britain Ministry of Agriculture, Fisheries and Food. Fishery Investigations (series 2):19:5-533.

Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin 74. 577p.

L Box, G.E.P., W.G. Hunter, and J.. Hunter. 1975. Statistics for Experimenters. John Wiley & Sons, New York.

L Cadrin, S.X. and D.S. Vaughan. 1997. Retrospective analysis of virtual population L estimates for Atlantic menhaden stock assessment. Fishery Bulletin U.S.

95:445-455. L Charmantier, G., M. Charmantier-Daures, and D.E. Aiken. 1991. Metamorphosis in the lobster Homarus (Decapoda): a review. Journal of Crustacean Biology 11(4):481-495.

Clayton, G., C. Cole, S. Murawski and J. Parrish. 1978. Common marine fishes of coastal Massachusetts. Massachusetts Cooperative Extension Service, Amherst, Massachusetts. 231p.

L Collette, B.B. and MacPhee, G. (Editors). 2002. Bigelow & Schroeder's Fishes of the Gulf of Maine. 3rd Ed. Simthsonian Institution Press. Washington and London.

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MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 3.3 Impingement Monitoring ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

IMPINGEMENT OF ORGANISMS on the INTAKE SCREENS at PILGRIM NUCLEAR POWER STATION JANUARY - DECEMBER 2004 Submitted to Entergy Nuclear Generation Company Pilgrim Nuclear Power Station Plymouth, Massachusetts ma MARINE RESEARCH. INC.

By Marine Research, Inc.

Falmouth, Massachusetts April 2005

Introduction Pilgrim Nuclear Power Station (PNPS) is located on the northwestern shore of Cape Cod Bay (Figure 1) with a licensed capacity of 670 megawatts. The unit has two circulating water pumps with a capacity of approximately 345 cfs (155,500 gallons per minute) each and five service water pumps (2,500 gallons per minute each) with a combined capacity of 23 cfs. Water is drawn under a skimmer wall, through vertical bar racks spaced approximately three inches on center, and finally through vertical traveling screens of l/ x %inch mesh (Figure 2). There are four vertical screens, two for each circulating water pump.

This report provides documentation of environmental monitoring and reporting requirements of NPDES Permit No. 0003557 (USEPA) and No. 359 (MA DEP) at PNPS. This report describes the monitoring of impinged organisms at Pilgrim Station based on screen wash samples taken from January to December 2004.

Methods and Materials Three scheduled screen wash periods were monitored each week from January to December 2004. These included the 0830 wash on Monday, the 1630 wash on Wednesday, and the 0030 wash on Saturday. Each sampling period thus represented a separate, distinct eight-hour period. Prior to each sampling period, the time of the previous screen wash was obtained from a strip chart recorder located in the screen house to permit the current sampling interval to be calculated. Whenever the screens were static upon arrival, a 30-minute sample was collected and, whenever the screens were operating continuously, a 60-minute sample was obtained.

Water nozzles directed at the screens washed impinged organisms and debris into a sluiceway which was sampled by inserting a collection basket made of stainless steel mesh. All fauna were identified and noted as being alive, dead, or injured. Fish were determined to be alive if they showed opercular movement and no obvious signs of injury. Fauna determined to be alive were measured for total length (mm), then released. Those determined to be dead or injured were preserved. In the lab, the weights (grams) and total lengths (mm) were recorded for up to 20 specimens of each species. The impingement rate was calculated by dividing the number of fish collected by the number of hours in the collection period. Couns made at each collection during a month were extrapolated to estimate a monthly total (X number of fish v sample hours) x 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> x number day per month) These monthly totals were sunmed to derive an annual total adjusted for number of collection hours.

If an impingement rate of 20 fish per hour was obtained for static washes, an additional one-hour sample was taken. If at least 20 fish were taken in the extra 60-minute period or immediately following a continuous wash, the Operator and Shift Manager were immediately informed and advised to leave the screens operating until further notice. In the interim, other communication typically occurred in order to keep all appropriate individuals updated. The contractor then collected two additional one-hour screenwash periods at four-hour intervals. If 20 or more fish/hour were taken in the fourth sample, screenwashes were monitored for one hour at eight-hour intervals until impingement rates declined to less man 20 fish per hour.

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. Figure 1. L-oeatonof Pilgrim Nuclear Power Station

'  : '- ' :r :'- .' .,

W-- E5. W aU i- r:-1IC C. r K f F r Fi -U W 1 It 4

I W

Figure 2. Crosssection of intake structure of Pilgrim Nuclear Power Station.

Results and Discussion Fish In 638.3 collection hours, an estimated total of 33,591 fish consisting of 35 species was collected during sampling from January - December 2004 (Table 1, Figure 3). Atlantic silversides (Menigd menidia), Atlantic menhaden, (Brevoortia tyrannius), grubby (yoxocephalus aenaeus), blueback herring (Alosa aesvivalis), winter flounder (Pseudopleuronectesanericamu), and rainbow smelt (Osmerus mordax) accounted for 92% of the annual total. The impingement rate for 2004 was 2.85 fish per hour (Table 1). Impingement of all fish was highest in November (17.79 fish/hour) and lowest in June (0.04 fish/hour).

Pilgrim Station Impingement L January - December 2004 31.1.

39.0%s L

6.00 6.1%

%-ih Ras 7 29Ee0gsm L

6.1nl _Rihnbow Smeft 6PS Gu3.31 33

• . L Fgure 3. Percent of total for numerically dominant species of fish Impinged on the Pilgrim Nudear Power Station Intake screens, January to December 2004.

L Atlantic silversides, histoncally one of the most numerous fish impinged at PNPS, ranked first with an estimated annual total of 13,107 fish, Silversides were most abundant in April (7,393 fish), when 56% of the annual total was collected C(able 1). Impinged silversides were young-of-the-year and age 1 fish ranging in size from 52 to 175 mm, and had a mean length of 94 mm (Table 2; Conover and Murawski 1982). L Atlantic menhaden ranked second in the 2004 catch with 10,431 extrapolated total fish collected and were most abundant in November when 58% of the annual total was impinged (Table 1). Most of the menhaden impinged were young-of-the-year between 30 and 97 mm, L

averaging 65 mm in length (Table 2).

L 4 Maine Research, Inc.

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Grubby ranked third accounting for 6.7% of the annual catch (2,257 fish, Table 1).

Grubby were most abundant in November and ranged in size from 39 to 120 mm with a mean length of 70 mm.

Blueback herring ranked fourth with 2,045 fish and were most abundant in December (1,552 fish) when 76% of the annual estimated total was obtained (Table 1). Blueback herring averaged 89 mmn in length and ranged from 56 to 137 mm suggesting they were young-of-the-year CTable 2).

Winter founder ranked fifth accounting for 6% of the annual catch (2,021 fish; Table 1).

Young-of-1he-year winter flounder dominated the catch which ranged in size from 35 to 340 mm with a mean of 70 mm (Table 2). There were only three fish greater than 150 mm (age 2 and older) sampled Winter flounder were most abundant in November with 36% of the estimated annual catch.

Rainbow smelt (1,092 fish) ranked sixth in 2004. Smelt were most abundant in November and ranged from 40 to 220 mm and averaged 105 mm total length.

Annual extrapolated totals for typical dominants impinged from 1980 to 2004 along with their respective 1980 to 2003 long-term means are shown in Table 3 and Figure 4. These fish typically account for greater than 90% of the annual total collected on the screens, averaging 91% from 1990 to 2003. In 2004, these species accounted for 95% of the annual total. The 2004 impingement total for all fish was 61% of the 14-year mean of 3,329 fish collected.

'Atlantic silverside were impinged in numbers slightly greater than their 24-year mean of 11,306 fish collected while Atlantic menhaden were taken in numbers just below their long-term mean of 11,226 fish. These two species typically ranked either first or second each year from 1980 to 2004 (Table 3). Grubby, blueback herring and winter flounder were also sampled in numbers 4, 2.6 and 2.3 times their respective 24-year means of 558, 777, and 871 fish. All other species except Atlantic tomood (Microgadus tomcod) and hakes (Urophycis spp.) were sampled in below average numbers (Table 3 and Figure 4).

Tmvintement Rates In 2004 there was one impingement event (220 fish/hour) which occurred on November

1. The impingement rate for that event was 145 fish/hour and the dominant species was young of the year menhaden (mean total length =62 mm; range 48 to 97 mm). Three additional samples were taken yielding impingement rates between 0 and 3 fish/hour, demonsting that the event lasted only a short period.

Previous large impingement events (21.000 fish) at PNPS since 1973 are documented in Table 4. There were no large impingement events in 2004. These events often occur in the late summer and autuni when young fish are abundant, actively moving offshore for the winter and water temperatures are declining. As water temperatures decline metabolism declines along with swimming ability.

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Impingement rates (number of fish collected divided by number of collection hours) for each species and their respective estimated annual totals are presented in Table 5. Silverside and L menhaden yielded the highest impingement rates (1.51 and 0.52 fish/hour, respectively). For all species combined, the impingement tes were 2.85 fish/hour and 34,485 fish/year, ranking eighth over the 25-year time series from 1980 to 2004 (Table 6). The average annual impingemnut total for 1980 to 2003 was 34,485 fish per year, ranging from 1,1 12 (1984) to L

179,608(2003) fishper year. L Since 1980, 73 species of fish have been collected on the PNPS intake screens (Table 7).

Nine species of fish (alewife (Alosapseudoharengus),Atlantic silverside, Atlantic tomcod, blueback herring, cumner (Tautogolabrusadspersus), grubby, hakes, rainbow smelt, and winter flounder) were collected every year from 1980 to 2004. Six other species (Atlantic herring, L

Atlantic menhaden, lumpfish (Clyclopterus hlnbus), rock gunnel (Pholisgzunellus), tautog (Tautoga onins), and windowpane (Scophthabmus aquosus)were present at least 90Me of the time

(Ž23 annual occurrences).

Invertebrates L From January to December 2004, 20,566 invertebrates representing 12 taxa Crable 8) were sampled yielding an impingement rate of 2.63 invertebrates per hour. Sevenspine bay shrimp (Crangon septemspinosa) were dominant accounting for 78% of the annual estimated L

total. They were primarily impinged in February and April when 64% of the 16,056 estimated total were collected. Rock crab (Cancerirroratus)was sampled every month except June, and ranked second (2,485 crabs) accounting for 12% of the annual total of all invertebrates impingedX L

Twenty-two American lobsters (Flomarus americanus) were impinged during sampling periods in 2004 ranging in size from 34 to 98 mm, yielding an annual total of 434 lobsters. Of the 22 lobsters collected the largest was of legal size e 82 mm) and the rest were less that 75 mm and L likely juveniles.

Fish Survival L Initial survival among fish impinged was recorded immediately upon removal from the collection basket (Table 9). Initial survival rates (number of fish alive/number of fish collected) for continuous wash periods (34%) were greater than those for static wash periods (19%). This reduced survival for the static washes could be attributed to the poor survivability for the large numbers of Atlantic silverside impinged. Among the four most abundant fishes impinged, L Atlantic silverside, Atlantic menhaden, winter flounder, and blueback herring, survival during continuous wash periods was higher than in static wasli periods. As in previous years, initial survival raes were typically higher duing continuous wash periods presumably due to the reduced exposure time on the screens (MRI 1983, Anderson 2000).

L Combined initial survival rates for static and continuous wash periods for each species in -

which more than 20 fish were sampled in 2004 was greater than 50% in each case except for Atlantic silverside Atlantic menhaden, blueback herring, and rambow smelt (7, 11, 30 and 8%,

respectively). These four species are generally sensitive to impingement effects. The high l combined survival rates for winter flounder and grubby (85 and 83%, respectively) were not 6 Marine Research, Inc.

surprising since their respective static survival rates (83 and 82%) indicated their high tolerance of impingement That is consistent with observations at other surface water intake structures (MRI 1997, and 1982).

Conclusions

1. The average hourly impingement rate for 2004 at Pilgrim Station from January to December was 2.85.

2. Thirty-five species of fish were sampled in 638.3 collection hours-in 2004.

3. Atlantic silverside, Atlantic menhaden, grubby, blueback herring, winter flounder, and rainbow smelt accounted for 39, 31, 7, 6, 6, and 3%, respectively, of the extrapolated annual total of 33,591 fish.

4. The estimated annual impingement total of 33,591 fish was 97% of the 1980 to 2003 mean of 34,485 fish, ranking eigth for the 25-year time series.

5. Invertebrates were impinged at a rate of 2.63 per hour. Sevenspine bay shrimp and rock crabs accounted for 78 and 12% of the 2004 estimated annual total of 16,056 invertebrates.

Literature Cited Anderson, R D.. 2000. Impingement of organisms at Pilgrim Nuclear Power Station (Januaiy-December 1999). In: Environmental Protection, Entergy Nuclear Generation Company.

Marine Ecology Studies related to operation of Pilgrim Station. April 30, 2000.

Conover, D.O. and S.A. Murawski. 1982. Offshore winter migration of the Atlantic silverside, Medi~anmenida. Fishezy Bulletin U.S. 80(1):145-150 MRI (Marine Research, Inc.). 1982. Brayton Point Impingement Survival Study, 1981, 1982.

Submitted to New England Power Conpany, Westborough, MA July 29,1982. 15+

appendix.

MRI (Marine Research, Inc.). 1983. Assessment of Finfish Survival at Pilgrim Nuclear Power Station 1982. Submitted to Boston Edison Company, April 11, 1983. 38p.

MRI (Marine Research, Inc.). 1997. Post-impingement survival study Manchester Street Station January 1996-February 1997. Prepared for Narragansett Electric Company and New England Power Company April 1997.

Marine Research, Inc.

7 MarineResearch,Inc.

AL.

Figure 4. Extrapolated annual totals for typical numerical dominants impinged at Pilgrim Nuclear Power Station, 1980-2004.

crw r- ram r-_ e el m L -T ram r- r- R- r wr- A If--

W- c r: r -. r. r.r U-r-1 -- r-, 1, C7' r U:

C rf_

F C Atlantic tomcod Hakes (Red and White)

Pilgrim Nuclear Power Station Impingement Pilgrim Nuclear Power Station Impingement 1.800 1.00.

1.600 1.400 So s. ...._ ................

I. 8XII 90 .. ....._. C..

I-E 40 o 0 . _._._

..__r ;1 20

• 19 IS83196*999 1969 1990*992 *94 19*I99 2000 2002 00 I"

• 3913 *9~ LVOP *9l 1 19 *3 199I 199 2001 2003

• 96 19t 1963 7 1969 *99 1 92 19 *99920010 NOI 10TOta~I 2003 lmOI9020 3Tobl-bM 31903 Figure 4. (continued).

Blueback Herring Cunner, Pilgrim Nuclear Powver Station Impingement Pilgrim Nuclear Powver Station Impingement

,200 1

- 00 ~~~~. . ....... ..=:._-==__

F *....196 196 ,6 968 199 1_2 199 *=99.4..928 200 200 I ll l1tS 1"Il 1904 1"6 Ign 199o 1992 1994 W6 19" NOO >l0 2004 MG 1"2 914 196

• 0112 9 1994 19" 0" 2002 0 19*J 1AM1#1 196 19"1 *91 5 91W 7 1999 2001 2N0 I M1 636 M 167* 19 19MI93 19" 1*997 19S9 2001 2003

. lgTObl-IBan 19802003 1 UllTOt -I 190 Figure 4. (continued).

or- "Ir rr-I -r I - -11f r-n - r~ r T ~ IT I

W - U - U"--- r- , 1 27-7 V7--- - U - IT Fr WI, K r ~ , II- U C - 5 Figure 4. (continued).

Table 1. Monthly extrapolated totals for all fishes collected from Pilgrim Station Intake screens, January-December 2004.

20Cn Common Name Soecies ISummary Ilan Feb -Mar Apt May Jun Jul -Aug Sep Oct Nov Dec Atlantic Silverside Menidia menkida 13,107 127 2 87 3,011 7,393 1,113 75 953 146 Atlantic Menhaden Brevoortia tranmis 10,431 93 41 15 848 247 786 8,309 91 Grubby Myoxocephalus aenaeus 2,257 51 119 43 178 42 15 37 1,542 310 Blueback Herring Alosa aesItiai 2,045 17 43 123 53 257 1,552 Winter Flounder Pseudoplewroneciesamericanus 2,021 119 147 57 383 138 IS 12 75 728 347 Rainbow Smelt Osmerus mordax 1,092 8 15 43 137 27 514 347 Atlantic Tomood Microgadussomcod 304 17 14 53 19 128 73 Cunncr Tautogolabrusadspersus 240 8 14 42 59 37 43 37 Little Skate Leucorqaaerinacea 237 42 30 61 19 86 Hakes (Red and White) Uropys app. 202 12 19 171 Threespine Stickleback Gajierosetusaculeatus 158 128 14 16 Black Sea Bass Cntropriftfisstria$4 147 19 128 Alewife Alosa pnwdoharengus 145 41 86 18 Striped Bass Moron. saxadtlis 139 93 27 18 Atlantic Herring Cluea harengus 138 110 11 18 Fourspot Flounder Paralichlhysoblongus 122 25 8 43 27 18 Striped Killifish Fundulus maJalt 121 14 27 37 43 Atlantic Cod Gadusmorhua 99 34 8 42 15 White Perch Morone americana 86 86 Scup Stenotonrus chrysops 72 8 36 27 Pollock Pollachhusvirens 53 11 43 Northern Searobin Prionous carolinus 51 8 43 Tautog Tautoga onifis 43 43 Summer Flounder Paralichdthsdentatus 41 41 Sand Lance Ammodyte spp 38 27 11 Windowpane Scophthalmus aquosws 37 15 21 Yellowtail Flounder Limandafmeruginea -37 37 Butterfish Peprilusiriacanthus 31 12 19 Rock Ounnel Phoils guwnelhis 24 14 11 Smooth Dogfish Mwtelus canis 16 16 Radiated Shanny Ulvarla subb frcala 14 14 Northern Pipefish Syngnathusfuaus 14 14 Ocean Pout Zoarcesamericamat 14 14 Lumpfisbh Cyclopterus lumpus 8 8 Atlantic Seasnail Lfparis tdawicus 8 8 SpeciesCount 35 11 11 9 18 13 2 6 6 4 11 17 13 ExtrapolatedTotals 33,591 509 635 3.397 8,612 :1,591 31 148 981 329 1,142 13,203 3,013 Number of "Collection Hours" 638.3 87.7 89.8 52.1 54.3 70.2 47.5 50.3 61.4 27.1 39.8 17.4 40.8 Impingement Rate (#1fishfour) 2.85 0.68 0.91 4.57 11.91 2.14 0.04 0.20 132 0.44 1.53 17.79 4.05 Marine Rseaarch, Inc.

9_7 U-7 r-_ r-77", r Ir .9 V. r-" r- r__ r__ U_ U____ (__ __ r___ U-1 r-,-- t----

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.-- Ur Ti~ Ti_' . if a - I Table 2. Species, number, length and weight for all fish impinged at Pilgrim Station, January - December 2004.

Number Length (mm) Weight (g)

Common Name Species Collected n Mean Min Max n Mean Min Max Atlantic Silverside Menidla menidfa 961 331 94 52 175 268 4 9 Atlantic Menhaden Brevoortla yra7mus 335 189 65 30 97 126 3 0 8 Winter Flounder Pseudopleuronectesamericanus 120 120 70 35 340 22 2 1 8 Blueback Herring Alosa aestivalls 110 68 89 56 137 52 4 1 15 Grubby Myoxocephalus aenaeus 87 56 70 39 120 8 5 1 9 Rainbow Smelt Osmerus mod= 48 47 105 40 220 40 8 1 62 Atlantic Tomcod Microgadus tomcod 16 16 103 51 196 1 11 11 11 Striped Bass Morone saxatilis 15 15 460 315 538 0 Cunner Tautogolabrusadspersus 15 14 102 47 210 4 7 1 14 Little Skate Leucorajaerfnacea 14 14 398 200 501 0 Threespine Stickleback Gasterosteusaculeatus 11 11 56 47 65 1 2 2 2 Atlantic Herring Clupea harengus 10 10 91 30 290 1 121 121 121 Atlantic Cod Gadusmorhua 10 10 111 54 165 3 11 2 26 Fourspot Flounder Parallchthysoblongus 10 10 64 47 103 1 1 1 1 Alewife Alosa pseudoharengus 6 6 99 59 172 5 10 1 37 Red Hake Urophycis chuss 6 5 113 74 190 2 4 4 S Striped Killifish Fundulusmajalls 5 5 77 67 94 0 Scup Stenotomus chrysops 5 5 49 32 80 4 2 1 6 Black Sea Bass Centropristissilata 4 4 70 51 88 2 5 2 8 Windowpane Scophthalmus aquosus 4 4 120 103 140 2 10 10 11 Sand Lance Ammodytes sp. 3 3 140 129 147 0 Summer Flounder Paralichthysdentatus 3 3 57 46 63 0 Pollock PotlachiusVrens 2 2 134 74 193 0 Northern Searobin Prionotuscarolinurs 2 2 72 47 97 1 2 2 2 White Perch Morone americana 2 2 164 92 236 1 8 8 8 Rock Gunnel Pholis gunnellus 2 2 123 110 136 0 Butterfish Peprilhstriacanthus 2 2 61 60 61 2 2 2 3 Yellowtail Flounder Llmandaferruglnea 2 2 143 66 220 1 74 74 74 Smooth Dogfish Mustelus canis 1 1 166 166 166 I 20 20 20 Northern Pipefish Syngnathusfuscus 1 12 149 147 150 0 Lumpfish Cyclopterus lumpus 1 1 93 93 93 0 Atlantic Seasnail Liparls aslantius I 1 - 63 63 63 1 3 3 3 Tautog Tautoga onliis 1 1 86 86 86 0 Ocean Pout Zoarcesamerltanus 1 1 165 165 165 0 Radiated Shanny Ulvarlasubbiircata 1 1 78 78 78 1 3 .3 3 Umrne Reseaarch Inc.

Table 3. Annual extrapolated totals for typical dominants found on the Pilgrim Station Intake screens, 1980-2004.

Mean Species 1980 1981 1982 1983 1984' 1985 1986 1987' 1988 1989 1990 1991 1992 1993 1994' 19954 1996 1997 1998 1999' 2000 2001' 2002 2003' 1990-2003 2004 Atantic silverside 191 90,449 2,626 1,586 245 4,417 702 1.298 940 2,838 4.761 2.955 2.381 9.872 36,498 13,085 16,615 6,303 6,773 8.577 25.665 4.987 4,430 23.149 11,306 13,107 Atlanticmenhaden 226 0 171 522 11 1,491 953 0 177 2,020 3.135 1,117 32 46 58 1,560 2,168 1,329 1,423 42,686 34.354 3,599 53,304 119,041 11,226 10,431 Winterflounder 297 249 297 232 47 884 908 138 556 1.119 336 694 787 1,181 1,018 1,628 857 608 2,069 1,021 1.358 1,729 1.466 1.435 871 2,021 Blueback herring 46 230 251 754 34 791 63 7 222 207 1,194 298 110 295 269 1,244 2.462 424 134 550 5,919 229 943 196S 777 2,046 Grubby 107 448 340 490 114 932 359 200 124 684 585 468 507 640 1,094 648 1,347 405 335 628 1,105 517 1,087 237 558 2,257 Rainbow smelt 814 236 634 1.224 29 189 1.909 1,070 370 886 387 372 317 8,302 9.464 2,191 3.728 1,978 1.656 875 13 879 335 532 1.600 1.092 Atlantic tomcod 63 76 221 276 157 389 174 57 1,578 433 291 159 104 329 153 260 466 72 40 302 323 278 168 19 266 304 Cunner 1,043 870 610 196 45 580 270 115 97 199 210 182 28 93 77 346 332 41 101 153 348 140 59 172 263 240 Atlantic herring 83 53 156 22 0 35 3,009 6 51 138 408 24,238 51 169 28 108 0 13 108 181 77 48 301 51 1.222 138 Alewife 99 201 262 83 88 807 261 26 464 149 1,480 250 247 1,021 123 39,884 216 317 158 610 2,443 1,618 334 438 2,149 145 Hakes(Red andWhite) 93 101 125 0 8 34 27 53 23 55 0 55 14 166 23 182 113 196 106 682 182 1,158 192 128 155 202 Windowpane. 68 96 107 173 56 146 87 0 0 171 171 103 41 133 179 232 296 65 416 434 363 162 24 13 147 37 Tautog 0 69 18 41 11 83 26 113 82 159 52 175 93 275 50 73 488 172 129 119 157 92 289 46 117 14 Lumpfish 38 0 160 103 75 125 46 72 674 30 78 51 122 329 177 116 206 173 244 136 131 0 137 61 137 8 Total above species 3,168 93,078 5,978 5,702 920 10,903 8,794 3.155 5,358 9,088 13,088 31,117 4,834 22.851 49,211 61,557 29,294 12,096 13,692 56,954 72,438 15,436 63,069 147,290 30.795 32,042 Total all fish 4,030 95,336 8,411 6,558 1,112 12,499 9,259 3,782 6,675 10,289 15,939 32.080 5,397 24,105 50,439 62,616 30,264 14,230 14.303 58,318 103,986 15,636 64,606 179,608 34,562 33,591 Percent of toal 79%. 98% 71% 87% 83% 87% 95% 83% 80% 88% 82% 97% 90% 95% 98% 98% 97% 85% 96% 98% 70% 99% 98% 82% 89% 95%

Collection Time (bn.) 687 574.8 687 763 1,042 465 806 5 525 618 919.5 930.3 774.0 673.5 737.4 607.7 416 455 575 375.5 507 430.1 494.4 714.1 638 638.3 Impingement Rate (all fish)

I No CWS pumps were in operation April to August 1984.

2 No CWS pumps were in operation August 1987 3 No CWS pumps woe in operation 9 October- 14 November 1994.

4 No CWS pumps were in operation 30 March -15 May 1995.

5 No CWS pumps were in operation 10 May - 1O June 1999.

6 No CWS pumps were in operation 28 April . 9 May 2001.

7 No CWS pumps were in operation 21 April -I1 May 2003.

Manwtnmk Ihn

[-l -,I W_ rf' {a V- n, F V7 - V7, -- r K .- n- r : -I r - F. I .t a . A.

Table 4. Dominant species and annual estimated number impinged from high impingement events at PNPS, 1973-2004.

Estimated Number Date =

Species for all Species August-September, 1973 Clupeids 1,600 August 5, 1976 Alewife 1,900 November 23-28, 1978- Atlantic menhaden 10,200 December 11-29, 1978 Rainbow smelt 6,200 March/April, 1979 1 Atlantic silverside 1,100 September 23-24, 1981 Atlantic silverside 6,000 July 22-25, 1991 Rainbow smelt 4,200 December 15-28, 1993 Atlantic silverside 5,100 November 26-28,1994 Atlantic silverside 5,800 December 26-28, 1994 Atlantic silverside and Rainbow smelt 11,400 September 8-9, 1995 Alewife 13,100 September 17-18, 1999 Atlantic menhaden 4,910 November 17-20, 2000 Atlantic menhaden 19,900 August/September, 2002 Atlantic menhaden 33,300 November 1, 2003 Atlantic menhaden 2,500 November 12 - 17, 2003 Atlantic menhaden 63,900 November 19 - 21, 2003 Sand lance and Atlantic menhaden 17,900 November 29, 2003 Atlantic silverside 3,900

sampled from Pilgrim Table 5. Impingement rates per hour and year for all fishes operation).

Station intake screens, January-December 2004 (assuming 100%

Estimated Dominant month of species Atlantic Silverside Rate/Hr 1.51 Annual Rate 13,107 occurrence April November Total Collected 961 335 L

Atlantic Menhaden 0.52 10,431 Wmter Flounder Blueback Herring 0.19 0.17 2,021 2,045 November December 120 110 87

!II

%O 0.14 2,257 November Grubby 48 0.08 1,092 November Rainbow Smelt 16

.0.03 304 November Atlantic Tomcod 15 0.02 139 April Striped Bass 0.02 240 15 Cunner Little Skate Threespine Stickleback 0.02 0.02 237 158 November March 14 11 10 L

Atlantic Herring 0.02 138 April 0.02 99 May 10 Atlantic Cod 0.02 122 March 10 Fourspot Flounder 0.01 145 November 6 Alewife 0.01 202 November 6 Red Hake 5 Striped Killifish 0.01 121 November August 5 Scup 0.01 0.01 147 November 4 Black Sea Bass Windowpane Sand Lance 0.01 0.005 37 38 May April April 4

3 3

L Summer Flounder 0.005 41 Pollock Northern Searobin 0.003 0.003 0.003 53 51 86 November November November 2

2 2

I White Perch 2 Rock Gunnel Butterfish Yellowtail Flounder 0.003 0.003 0.003 24 31-37 April

-October December 2

2 L

0.002 16 June 1 Smooth Dogfish 1 Northern Pipefish 0.002 14 April Lumpfish 0.002 8 January 8 February I Atlantic Seasnail 0.002 Tautog Ocean Pout Radiated Shanny 0.002 0.002 0.002 43 14 14 November April March 1' L Total 2.85 33,591 1,817 6

6 Marine Resea ar h Inc.

6

Table 6. Hourly, daily, and estimated annual impingement rates for all species combined and annual dominants collected on the PNPS Intake screens, 1980-2004.

Year Fish/Hour Fish/Year Dominant Species (NumberNear) 1980 0.66 4,030 Cunner (1,043) 1981 10.02 95,336 Atlantic silverside (90,449) 1982 0.93 8,411 Atlantic silverside (2,626) 1983 0.57 6,558 Atlantic silverside (1,586) 1984 0.13 1,112 Atlantic silverside (245) 1985 1.14 12,499 Atlantic silverside (4,417) 1986 1.26 9,259 Atlantic herring (3,009) 1987 0.28 3,155 Atlantic silverside (1,298) 1988 0.27 6,675 Atlantic tomcod (1,578) 1989 0.80 9,088 Atlantic silverside (2,838) 1990 1.70 15,939 Atlantic silverside (4,761) 1991 3.38 32,080 Atlantic herring (24,238) 1992 0.63 5,397 Atlantic silverside (2,381) 1993 2.78 24,105 Atlantic silverside (9,872) 1994 5.97 50,439 Atlantic silverside (36,498) 1995 5.87 62,616 Alewife (39,884) 1996 3.11 30,264 Atlantic silverside (16,615) 1997 1.43 14,230 Atlantic silverside (6,303) 1998 1.30 14,303 Atlantic silverside (6,773) 1999 7.21 58,318 Atlantic menhaden (42,686) 2000 9.25 103,968 Atlantic menhaden (34,354) 2001 1.78 15,636 Atlantic silverside (4,987) 2002 4.93 64,606 Atlantic menhaden (53,304) 2003 25.58 179,608 Atlantic menhaden (119,041) 1980 to 2003 Mean 3.79 34,485 2004 2.85 33,591 Atlantic silverside (13,107)

MarineResearch Inc.

Table 7. Species collected on the Pilgrim Station Intake screens, 1980-2004.

Common Name Species 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 Alewife Alosa pseudoharengus x x x x x x x x x x x x x American Eel Anguila rostrata x x x x x x Amnerican Plaice Hippoglossoldesplatessoldes American Shad Alosa sapidissima K Atlantic Cod Gadus morhua x K K K K x x Atlantic Herring Clupeaharengus x K K K K K K K x x x K Atlantic Mackerel Scomber scombrus x Atlantic Menhaden Brevoortla tyrannus x K X K K x K -X K ~X K Atlantic'Moonfish Selene setapinnis K Kx K K Atlantic Silverside Menfdla menfida x x K X K K x x K K K K K Atlantic Tomcod Microgadustomood x x K K K K K K K Kx K K K Bay Anchovy Anchoa mitchif x K K K K K Bigeye Priacanthusarenatw K Black Ruff Centrolophorusniger x Black Sea Bass Centropristisstriata x K K x x x Black Spotted Stickleback Gasterosteuswheatlandi K Blueback Herring Alosa aestivalis K X K X K K x K x x x x x Bluefish Pomatomus saltatrix K Butterfish Peprilustriacanthus K K K K I K Cunner Tautogolabrusadspersus K K X K K K K K K X K K K Flying G(umard Dactylopterus volftans K Fourbeard Rockling Enchelyopus cimbrius Fourspine Stickleback Apeltes quadracus x x Fourspot Flounder Paralichthysoblongus K K X K K K K Gizzard Shad Dorosomacepedlanum Goosefish Lophius americanus Grubby My-oxocephalus aenaeus K K X K K K K K K K K K K Gulf Stream Flounder Citharichthysarcuifrons Hakes Urophycisspp. K K K K K K K K K K K K K Hogchoker 7Tinectes maculatus K Little Skate Leucorajaertnacea K K K K I K, K K K K x x Longhorn Sculpin Myoxocephalus octodecemspinosus Kx K Lumpfish Cyclopteruslumpus x K K K K X K K K K x x Mummichog Fundulusheteroclitus K x K K Northern Kingfish Menticirrhussaxadlls K Northern Pipefish Syngnathusfuscus K K K K K K x K K K K Northern Puffer Sphoeroides maculatus K K K

_- . r, l-. IFr .._. r-- r - U.- U~ r-

V_-

V-- ~V- r - ci FI r uF fr c Table 7. (continued).

Common Name Species 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 Northern Searobin Prionotus carolinus x x x x x x x x x x Ocean pout Zoarces americanus Orange Filefish Aluterus schoepfli K Weitzman's Pearlside : Maurolicus weitmani Planehead Filefish Monacanthus hispidus K Pollock Pollachius virens K K K K K K K K K Radiated Shanny UIvaria subbffmcatd K K K K K K K K K Rainbow Smelt Osmerus mordax K K K K K K K K K K K K K Rock Gunnel Pholls gunnellus K K K K K K X K K X K KC K Round Scad Etrumeus teres K K Sand Lance Ammodytes sp. K K K K K K K Sculpin sp. Myoxocephalus Jpp. K K Scup Stenotomus chrysops K K K K K K K K K Atlantic Seasnail Liparfs atlandacus K K K K K Sea Raven Hem tripterusamericanus K Shorthorn Sculpin Myxocephalus scorpfus K Silver Hake Merluccius blllnearus x x x x x x K Silver-rag Arlomma bondl x K Smallmouth Flounder Etropus microstomus x K K Smooth Dogfish Mustelus canis x x x K K K x Smooth Flounder Plevronectespunami Spiny Dogfish Squalus acanthus x x Spot Lelostomus xanthurus Striped Bass Morone saxatdfis Striped Cusk Eel Ophidfon marginalum Striped KillifishI Fundulus majalls x x K K K K K K K K Striped Searobins PrIonotus evolans x K Summer Flounder Paralichthys dentatus K K K K Tautog Tautoga ondtis K K K K K K K K K X K K Threespine Stickleback Gasterosteus aculeatus K K X K K K X K K X K K Weakfish Cynoscdon regalls White Perch Morone americana K K K K Windowpane Scophthalmus aquosus K K K K K K K K K K K Winter Flounder Pleuronectesamericanus K K K K K K K K K K K K K Winter Skate Leucoraja ocelata K K K K Yellowtail Flounder Limandaferruginea K X

Table 7. (continued).

Common Name Species 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Alewife Alosa pseudoharengus K K K K K K K K K K K K American Eel Anguilla rostrata K American Plaice Hippoglossoldesplatessoldes K American Shad Alosa sapidiusima Atlantic Cod Gadus morhua x x x x K K x x Atlantic Herring Clupea harengus x x x K K K K K K K K Atlantic Mackerel Scomber scombrus x Atlantic Menhaden Brevoortiatyrannus x x x x x x x x K x x x Atlantic Moonfish Sekne setapinnis x x x x Atlantic SlIverside Menidla menidla x x x x x x x x x x x x Atlantic Tomcod Microgadustomcod x x x x x x x x x x K K Bay Anchovy Anchoa mitchillt x x K Bigeye PrIacanthusarenatus Black Ruff Centrolophorusniger Black Sea Bass Centropristisstriata x x x x Black Spotted Stickleback Gasterosteuswheatlandt x x x Blueback Herring Alosa aestivalls x x x x x x x x x x x x Bluefish Pomatomussaltatrix x Butterfish Peprilustriacanthus x x x x x x x K Cunner Tautogolabrusadspersus x x x x x x x x x K K K Flying Gurnard Dactylopterus volitans x x Fourbeard Rockling Enchelyopus cimbrius x Fourspine Stickleback Apehtes quadracus K Fourspot Flounder Paralichthysoblongus x x X x x K K Gizzard Shad Dorosomacepedlanum x Goosefish Lophius americanus x Grubby , Myoxocephalus aenaeus x x x x x x x x K. K K K Gulf Stream Flounder Citharichthysarctlifrons x Hakes Urophycts spp. x x x x x x x x K K K K Hogchoker Trinectes maculatus Little Skate Leucorajaerinacea x x x x x x x x x x Longhorn Sculpin Ayoxocephalus octodecemspfnosus x x x x Lumpfish Cyclopterus lumpus x x x x x x x x x x x x Mummichog Fundulus heteroclltus x x x x x Northern Kingfish Mentfclrrhw saxatilis Northern Pipefish Syngnathusfuscus x X x x x x K x Kx x Northern Puffer xx Sphoeroldes maculatus x . x x or- r-. r-, r-. r r r_n 9 r, - r., r-. r r __ __ r-_ U----- F-- 7 ,- r__

W --.1 U 1 r- Urz- t- 9 Ir- -, V-- -- W Kl r 17 I rr I rr I IE-,

WI-r N- i Table 7. (continued).

Common Name .

Species 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Northern Searobin Prionotus carolfnus x x x x x x x x x Ocean pout Zoarces americanus x x Orange Filefish Aluterus schoepflf Weitzman's Peariside Maurolicus weilmani x x x Planehead Filefish Monacanthushispidus Pollock Pollachiusvirens x x x x x x Radiated Shanny UharIasubbfurcata x x x x x x x x x x x Rainbow Smelt Osmerus mordax x x x x x x x x x x x x Rock Gunnel Pholls ggnnellus x x x x x x x x x x Round Scad Etrumeus teres Sand Lance Ammodytes sp. x x x x x x Sculpin sp. aoxocephalus spp. x x Scup. Stenotomus chrysops x x x x x Atlantic Seasnail Liparis atlantdcus x x x x x Sea Raven Hemitripterusamericanus Shorthorn Sculpin M ocephalus scorplus Silver Hake Merlucchus bilinearus x Silver-rag Arlomma bondf Smallmouth Flounder Etropus microstomus x x Smooth Doghish Mustelus canis x x Smooth Flounder Plewronectesputnami x Spiny Dogfish Squalus acanthus x IC I Spot Lelostomus xanthurus x Striped Bass Morone saxatifis x x x x Striped Cusk Eel Ophidfon margfnatum x x Striped Killifish Fundulus majalls x x x x x X X X X X x Striped Searobins Prionotus evolans X X x x Summer Flounder Paralichthys dentatus X x X x Tautog Tautoga onifts x x x X X X X X X X X K Threespine Stickleback Gasterosteus aculeatus x X X X X X X X X K Weakfish Cynoscion regalis X X White Perch Morone americana x x x Windowpane Scophthalmus aquosus x X X X X X X X X X X x Winter Flounder Pleuronectesamericanus X X X X X X X X X X X x Winter Skate Leucoraja ocelata Yellowtail Flounder Limandaferruginea - x x x x

Table 8. Monthly extrapolated totals for Invertebrates impinged on the PNPS Intake screens, January - December 2004.

Common Name Jan Feb Mar Apr May Jun Jul Aue Sep Oct Nov Dec Total Nematode 8 8 Nereis 42 8 143 199 392 Squid 21 15 59 73 27 37 41 274 Sevenspine Bay Shrimp 1,282 3,069 2,512 7,221 1,538 124 310 16,056 American Lobster - 40 85 15 12 56 207 18 434 Hermit Crabs 19 19 Spider Crabs 41 41 Rock Crabs 85 70 371 66 42 59 182 27 562 912 110 2,485 IJapanese Shore Crab 8 13 22 Green Crabs 8 8 14 66 15 15 36 56 166 55 440 Lady Crabs 19 124 143 Starfish 26 24 19 166 18 254 Total 1,435 3,154 3,040 7,632 1,686 45 133 327 53 767 1,782 511 20,566 Number of Hours 87.65 89.81 52.13 54.34 70.16 47.5 50.3 61.42 27.14 39.75 17.37 40.75 638.3 Impingement Rate (#hour) 1.93 4.53 4.09 10.60 2.27 0.06 0.18 0.44 0.07 1.03 2.48 0.69 2.63 MarineResearch, Inc.

r-7 rr- r7- ir ] r- -r ra a r-m ran rr-r F r-_ r-

Table 9. Summary of initial survival rates for fish impinged on the PNPS intake screens, January-December, 2004.

Continuous Static Combined Number Percent Number Percent Number Percent Species Collected Survival Collected Survival Collected Survival Atlantic Silverside 64 35% 897 5% 961 7%

AtlnticMenhaden 165 13% 170 8% 335 11%

Winter Flounder 21 96% 99 83% 120 85%

BbuebackHerring 18 65% 92 23% 110 30%/e 3rubby I1 91% 76 82% 87 83%

RanbowSmelt II 18% 37 5% 48 8%

AtanticTomcod 5 60Ye 11 64% 16 63%

Cunner 8 50% 7 43% 15 47%/

Strped Bass 12 8% 3 100%/e 15 270/

ite Skate 5 100I% 9 100°/e 14 100%/e TheespineStickleback 6 100%KY S 80%/e 11 91%

tlanticoCd 3 33% 7 57% 10 50Ye tticHeating 1 100%/e 9 0%/ 10 10%

Foursot Flounder I 00/% 9 78% 10 70%/e lewife 1 0°/e 5 200% 6 17/6 RedHake 1 100°/e 5 40% 6 50C/

Scup 3 0°/e 2 5 0°h Sriped Kilifish 2 100°/e 3 100°h 5 100%

BckSea Bass 3 33% 1 0°/e 4 25%

Windowpane 4 75% 4 75%

Sand Lance 3 100°/. 3 100%/e Sunmnmer Flounder 3 100°/e 3 100%/e Buttefish 1 0 1 0%/a 2 0°/e NortnSearobin 2 50° 2 500%

Pohlock 2 100°/ 2 100%/e Rock Gunnel 2 100°h 2 100%/

White Perch 2 0°/e 2 0%/

Yellowtail Flounder 2 50% 2 50° Atlantic Seasnail 1 100%/e I I00%

1 Imipfsh 100°/e I IOP/0 othernPipefish 1 100°/e 1 IOOP/D Occan Pout 1 100%/e 1 100°/

Radiaed Shanny 1 100°0 1 100/

Smooth Dogfish 1 0°/. 1 0°/.

TautOg I 100%/ I 1000/.

Marine Research, Inc.

MARINE ECOLOGY STUDIES Pilgrim Nuclear Power Station Section 3.4 Hatchery Release & Collection Study ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

Hatchery Production Study Young-Of-The-Year Winter Flounder Post-Release Collections 2000 - 2004 Conducted For Entergy Nuclear - Pilgrim Station By Marine Research, Inc.

February 2005

2 Introduction Winter flounder, Pseudopleuronectes americanus, is an important commercial, recreational, and estuarine indicator species. Entergy's Pilgrim Nuclear Power Station (PNPS) monitors the local winter flounder population to assess potential impacts of plant operations on the Cape Cod Bay ecosystem. To assess the feasibility of contributing to the local winter flounder stock and mitigating potential entrainment impacts from PNPS tagged young-of-the-year (YOY) winter flounder were released into Plymouth Harbor annually from 2000-2004 and included Duxbury Bay in 2001. This report summarizes follow-up sampling and ancillary studies completed to determine growth and survival of L

hatchery-reared individuals released into the wild.

Briefly, assessments from 2000 through 2004 demonstrate: 1) released hatchery-reared fish not only survive, but convert to wild food sources and thrive after release; 2)

L released hatchery fish feeding behavior is similar to wild fish feeding behavior; 3) released hatchery fish survival approximates wild fish survival, consistent with the pen studies discussed herein. In short, the assessments support the continued use of and L

reasonable reliance on hatchery enhancement as a mitigation tool. L Methods 2000 to 2004 Release Methods To assess the feasibility of contributing to the local winter flounder stock and mitigating potential PNPS entrainment impacts approximately 104,450 hatchery-L produced winter flounder were released to Plymouth Harbor and Duxbury Bay from 2000-2004 (Table 1) by Marine Research, Inc. biologists. Hatchery fish were released in Plymouth Harbor in lots over 2 or 3 days, in the vicinity of the Plymouth Yacht Club L

(Figure 1, Site 1). This site was selected due the large numbers of wild YOY winter flounder at the location, ensuring suitable habitat for hatchery fish. In 2001, hatchery fish were also released in Duxbury Bay, just south of Powder Point (Figure 2). In general, methods for release and post-release sampling were similar from 2000-2004 although improvements to procedures were employed as experience was gained.

Winter flounder were reared by Llennoco, Inc., Chatham, MA, from Cape Cod L

Bay spawning stock. Prior to release, hatchery reared fish were implanted with a visible fluorescent implant elastomer mark (Figure 3) at the hatchery. Tag colors varied each year: 2000 tags were red, 2001 tags were green, 2002 tags were yellow, 2003 tags were L

green, and 2004 tags were orange. Tags were visible with an unaided eye, however, a 7-LED halogen dive light with a blue filter lens and amber glasses were employed to improve tag recognition.

L Hatchery fish were transported to the release site in aerated 15-gallon Rubbermaid plastic totes in 2000, 2001 and the first batch released in 2002. The remainder of the 2002 fish and all hatchery fish released in 2003 and 2004 were transported in plastic bags L

with oxygen added. Fish were released on a low incoming tide. In 2000, fish were allowed to acclimate for 1-2 hours prior to release in a 4 ft by 4 ft by 8 ft, 1/44-inch nylon L

Marine Research, Inc.

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3 mesh holding pen staked in shallow water at the release site. Hatchery fish were released directly into the water in subsequent years.

Hatchery-reared fish were released when wild YOY winter flounder were present from 2000-2002. In 2000, hatchery-reared flounder were released in late-July, at about half the size of the wild YOY fish collected at that time. Hatchery-reared fish were similar in size to wild YOY fish caught at the time of release in 2001 and 2002 (Table 1).

Fish were released earlier in 2003 and 2004 before wild YOY winter flounder had settled and disbursed to nearshore areas, as evidenced by seine collections. (Table 1).

2000 to 2004 Recapture Methods To gather information on the survival, distribution, and growth of hatchery-reared flounder beach seining was conducted in Plymouth Harbor near the release site (Figure 1, Site 1) from 2000-2004, on the west side of Plymouth Beach (Figure 1, Site 2) from 2002-2004, and at the Duxbury Bay release site (Figure 2) in 2001. Two beach seines were used in 2000 and 2001, each constructed of 1/4/4-inch mesh; one measured 50-ft x 6-ft and the other 100-ft x 6-ft. The hauls encompassed approximately a 214 m2 area with the 50-ft net or a 400 ni2 area with the larger 100-ft net. From 2002-2004 the larger net was employed exclusively, with one exception in 2004 where the smaller net was used (Tables 2 to 9).

Seine collections were conducted one hour before low tide through the slack and early flooding tide from 2000-2002. In 2003 it was found that large numbers of hatchery and wild fish were collected during the flood tide. Thereafter, seining started at or shortly after low tide and continued during the flooding tide. All winter flounder captured in each seine haul were counted and transferred to plastic buckets with aerated seawater or to floating mesh baskets. After all seine hauls were completed total length was measured to nearest nmm on all tagged, wild Age 1+, and up tolOO wild YOY fish.

As many as 20 fish were occasionally preserved for stomach content analysis, all other fish were released. The number of hauls conducted on each sampling date varied (Tables 2 to 9).

To determine the growth rate of wild YOY, wild Age 1+ and uncaged hatchery-reared flounder the' average size of fish collected in seine hauls was calculated and plotted against date' using linear regression for each group, where the slope represented the growth rate in millimeters per day.

DispersalSurvey:

To determine how far released fish might move from the release site seine sampling was carried out on one date at 4 stations in Plymouth Harbor (Figure 1, Site 1-

4) in '2003 and 5 stations in Plymouth Harbor (Figure 1, Site 1-5) in 2004. Flounder obtained in these seine hauls were checked for marks, counted, and measured as described above (Tables 6 to 9).

Additional Sampling:

To gather information on the survival and distribution of hatchery-reared flounder in bottom areas beyond the reach of seines a beam trawl was used in 2000. The beam Marine Research, Inc.

4 L trawl measured one meter across the mouth and was constructed of 1/44-inch mesh. Beam L trawl tows, conducted from a 14-ft, outboard-powered skiff, varied in length but start and end points were recorded with a GPS. Given the effort required to use the beam trawl, the relatively~small area it sampled, and its limited results, the approach was discontinued L after 2000; instead the effort was directed to holding pen studies.

To obtain insight on the efficiency of the 50-ft beach seine for collecting recently released hatchery fish, marked individuals were released in the path of the seine as it was L being deployed in 2001. This was done once in Plymouth Harbor and once in Duxbury Bay. In Plymouth Harbor the marked fish were released as the seine was being hauled while in Duxbury Bay the seine haul was not completed for 25 minutes following release of the marked fish. Flounder obtained in these seine hauls were checked for marks and U

counted. '

Stomach ContentAnalysis To determine whether hatchery and wild YOY winter flounder consume the same prey items, as many as 20 fish collected in selected beach seine hauls were preserved in L

10% formalin from 2001-2004. Wild and hatchery YOY were preserved on the same day when available so that stomach contents could be compared. In the laboratory winter L flounder total length was measured to the nearest mm, the stomachs were removed, sliced open and the contents flushed into a sieve. Prey items were sorted, identified to lowest possible taxonomic group, counted, and the percent stomach volume of each taxonomic L group was visually estimated (Stehlik and Meise 2000). Stomach content weights were unable to be obtained since entire stomach contents were less than 0.01 g. [

HoldingPen Methods 2001 To provide information on growth and survival wild and hatchery-reared flounder were transferred to holding pens in Plymouth Harbor and in Duxbury Bay under the L

Powder Point Bridge for various lengths of time (Table 10). With the exception of the first night, the pens used in Plymouth Harbor were cylindrical, constructed of 1-inch wire mesh lined with 1/4-inch plastic mesh, and measured 4 feet in diameter by 1 foot deep.

Due to shipment failure, a temporary holding pen was constructed of 1/8-inch nylon L

mesh, and measured 3 feet in diameter by 4 feet deep for the initial June 4 overnight period. The temporary holding pen was stocked with 50 hatchery flounder and 18 wild L YOY winter flounder and staked in subtidal water near shore adjacent to the Plymouth Harbor Yacht Club dock. Seven wire-mesh pens were set on June 19, two pens were placed in shallow water approximately 3 feet deep adjacent to the Yacht Club and four L were situated on the eastern side of Plymouth Harbor in water approximately 7.5 feet deep at low water. These pens were stocked with 18 hatchery fish and 18 wild YOY winter flounder. An additional pen was stocked with approximately 200 hatchery fish intended for used in Duxbury Bay pens.

The pens used in Duxbury Bay were circular, constructed of 1/8-inch rigid plastic mesh fitted to a 1-inch polyethylene pipe frame, and measured 36 inches in diameter by L 18 inches in height. These pens were deployed on June 22 and June 27. On June 22 two Marine Research, Inc.

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5 pens were set up containing 12 hatchery fish and 15 wild fish each. These pens were harvested on June 27. The pens were set up again with new fish on June 27, one with 25 hatchery fish and 14 wild YOY, and the other with 18 hatchery fish and 23 wild YOY.

2002 In 2002, wild and hatchery-reared flounder were transferred to holding pens following the same procedures and using the same hardware as in 2001. Seven wire-mesh pens were set in Plymouth Harbor on June 13, four in shallow water approximately 4 feet deep and three in water approximately 10 feet deep at low tide. Each pen was stocked with 15 wild and, 15 marked hatchery fish and were maintained for various lengths of time (Table 11).

2003 A new pen design was employed in 2003 for this study, which had proven effectiveness based on studies published by Meng et al. (2000). The pens were constructed. of welded metal frames and wood covered with 0.16 inch plastic mesh, measuring 4 feet long by 3 feet wide by 28 inches tall, with 9-inch long steel edges used to dig into the sediment (Figure 4). Edges were pushed into the sediment deep enough to prevent predators from burrowing into the pen from the bottom and fish within the pen from getting out. Pens had open-bottoms and removable tops secured by wing-nuts. The open bottom of these pens was the primary difference between this design and the mesh-bottom design previously used. The open bottom allowed flounder access to benthic food resources and natural substrate to burrow in. Pens were anchored in a silty-sand bottom substrate and rigorously cleared with a dipnet over a period of ten minutes to remove predators and other fish from the pens prior to stocking with young flounder. Naturally-occurring YOY winter flounder were found while clearing the pens for setup (10 flounder/m2 , in one case), confirmed that suitable substrate was selected for the experiment. Once it was determined the pens were clear, hatchery fish were measured and placed in the pens. This procedure was conducted during low tide, when the tops of the pens were exposed.

24-hour survival studies: To provide an estimate of the immediate, short-term survival of hatchery fish after transport and introduction into the bay, a 24-hr survival study was conducted. On each of two dates, May 15 and May 20, 2003, 50 fish were placed in a pen for a 24-hour period then removed and counted. The density of fish in the pen was extremely high and not meant to represent natural conditions.

Long-term (LT) survival studies: Eight growth and survival experiments were conducted from May 20 to September 30. The length of the experiments varied, from 49 to 86 days (Table 12). All pens were maintained just off the beach at Plymouth Yacht Club (Figure 1, Site 1). Pens were cleaned regularly during extreme low tides to prevent fouling. Once a month fish were removed from the pens, measured for total length, and moved to a clean pen placed over fresh substrate. To determine the growth rate of caged hatchery-reared flounder average size of fish was calculated and plotted over time; the slope provided the growth rate (mm/day).

For the first experiment 10 YOY hatchery winter flounder were placed in a 3 foot long by 3 foot wide by 17 inch tall pen, from May 20 to June 17. The pen used for this experiment was smaller than the pens described above used for experiments 2 thru 7. Six MarineResearch, Inc.

6 pens as described above were maintained from June 17-August 13 (Table 12), each was stocked with 5 hatchery-reared winter flounder. Five fish were used at the beginning of all but the first long-term experiment to prevent overstocking and the potential for reduced growth and survival due to limited food supply. One of the six pens set up on June 17 was stocked using 5 fish from the May 20-June 17 experiment. The remaining five pens were stocked with fish transported directly from the hatchery on June 19 and were maintained from-June 19-August 12 or 13 (55+ days). Two pens were maintained from August 13-September 30 (49 days) with 5 fish each, transferred from pens cleaned on August 13. One group of fish (Experiment 1) was held together from May 20 (the second release date) to August 13, and then transferred into another pen (Experiment 7) with fish held since June 19, then kept until September 30; cumulatively, these fish were penned for 134 days. On August 13 a second pen (Experiment 8) was setup with 5 tagged fish taken from experiments harvested on that date (LT#2-6), and was maintained L until September 30.

2004 '

In 2004, hatchery-reared flounder were transferred to holding pens following similar procedures and using the same hardware as in 2003.

24-hour survival studies: To provide an estimate of the immediate survival of hatchery fish transported and introduced into the bay, we placed 50 fish in a pen on the May 10 and May 11 release dates. We returned 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> later and counted the survivors.

Fish recovered on May 10 were preserved in 10% formalin for size analysis. Thirty fish recovered on May 11 were used in the long-term survival study, all remaining recovered fish were preserved for size analysis.

Long-term survival study: To provide an estimate of the long-term growth and survival of released hatchery fish six pens were set in Plymouth Harbor just off the beach at Plymouth Yacht Club near the release site (Figure 1, Site 1). Each pen was stocked with 5 hatchery winter flounder recovered from the May 11, I24-hr study. To minimize fouling, pens were cleaned once a month on neap tides. The fish were removed, measured for total length, and moved to a clean pen placed over fresh substrate. Pen condition, sediment, and predators were noted. The pens were maintained until September 29 (Table 13) at which time fish were preserved in 10% formalin for gut content analysis. To determine the growth rate of caged hatchery-reared flounder average size of fish was calculated and plotted over time.

Results:

Seine and recapturestudies 2000 Table 2 presents a summary of beach seine and beam trawl collections completedL in Plymouth Harbor during the summer and autumn of 2000 intended to determine if the hatchery fish survived. While a total of 1,887 wild young-of-the-year winter flounder were collected between July and November, no marked recaptures were identified. L MarineResearch, Inc.

7 2001 Beach seine collections completed during the summer and autumn of 2001 were tabulated separately below for the Plymouth Harbor and Duxbury Bay release sites (Table 3, 4).

An estimated total of 963 young-of-the-year winter flounder were collected on seven occasions in Plymouth Harbor adjacent to the Yacht Club (Table 3). The number is approximate because on June 18 some 200 young flounder were obtained in a single seine haul. These fish were intended for use in the holding pens and every effort was made to minimize stress by transferring them quickly from the seine to buckets of water.

While an accurate count was not obtained, the fish were carefully checked for marks.

Overall six recaptures were obtained, four on June 18, 14 days following release, one on August 2, 59 days following release, and the last on September 7, 95 days following release. Recaptured fish exceeded the mean length of wild fish collected on the same respective day. This was particularly true for the individuals collected on August 2 and September 7; they were 70 to 80% larger than the average wild fish (78 vs 43 and 88 vs 52 mm total length, respectively) and exceeded the length of the largest fish (68 and 85 mm, respectively) by 10 millimeters on August 2 and by 3 millimeters on September 7.

The number of recaptures (N = 6) was insufficient to calculate growth and survival rates.

In Duxbury Bay 426 young-of-the-year flounder were collected with one recapture being obtained on July 11, 27 days following release, assuming the marked fish was from the June 14 release (Table 4). In this case the recaptured fish was small (39 mm) relative to the average length of wild flounder collected on the same day (mean length = 46 mm), although wild fish as small as 25 mm were collected.

Trials in which marked flounder were released in front of the seine suggested that recapture efficiency at least immediately following release could be very low. On June 4 approximately 50 marked fish were released in the path of the seine in Plymouth Harbor.

A total of 19 winter flounder juveniles were captured, only one of which was marked.

On June 12 approximately 250 marked individuals were released in the path of the seine at the Duxbury site. Thirty marked fish were recaptured along with 15 wild flounder.

These results suggested that upon release young flounder drop to the bottom and likely remain motionless for an undetermined recovery period. With this. behavior the seine simply passed over them. This is consistent with repeated field observations where young hatchery flounder were found to drop passively to the bottom after being measured and released. Individuals have been observed landing on their eyed side where they remain inverted for several minutes. In contrast, wild fish appear more likely to rise from the bottom and dart short distances forward in "leap frog" fashion in advance of the lead line of the seine until it reaches shallow water. Others will rise from the bottom and turn into the net to be captured. Since wild flounder were collected in nearly every seine haul completed in both Plymouth Harbor and Duxbury Bay, they would have to be very abundant to account for the numbers taken if they behaved the same as recently released hatchery fish.

2002 Table 5 summarizes information on number and mean total length of YOY winter flounder captured in the seine survey for the summer and autumn sampling period of 2002. A total of 1,815 YOY winter flounder were collected over sixteen sampling events Marine Research, Inc.

8 in Plymouth Harbor adjacent to the Yacht Club and one sampling event on the eastern L side of the harbor (Figure 1, Site 2). Overall, 32 hatchery fish were recaptured from June 4 to September 12; 4 to 100 days after release. On 6 of the 7 days on which recaptures were collected, hatchery fish exceeded the mean length of wild fish collected on the same L day (Figure 5). Although sample size was small, growth among hatchery fish appeared comparable to that of wild fish (hatchery growth rate = 0.30 mm/day, R2= 0.77, p <

0.001; wild growth rate = 0.26 mm/day, R = 0.98, p < 0.001). L 2003 Abundance/density L A total of 144 tagged hatchery winter flounder were collected in the beach seine survey during 2003 (Table 6). These fish were collected over 14 sampling events, following release on May 15 and May 20.- Interestingly, hatchery' fish were not L recaptured during the first three sampling events (May 16-May 21) suggesting an initial, rapid dispersal from the release site perhaps in response to a spring tide. The fish clearly returned to the point of release however. 90% of the recovered hatchery fish were caught within 60 days of release. The remaining 10% were recaptured 64, 73, 78, 119, and 133 days after the May 20 release. The decrease in recaptures over time probably reflects a combination of mortality and dispersal. On August 1 a hatchery fish was recaptured at Site 2, approximately 1,650 m from the release site (Figure 1).

A total of 2,646 wild winter flounder were collected in the beach seine in 2003.

Of the total, 2,485 were young-of-the-year (age-0) and 160 were age 1 or 2 (Tables 6, 7). L In the initial seine collections completed on May 15, May 16, May 28, June 4 and June 6 age one and age two wild winter flounder were collected, but wild young-of-the-year were not. Wild YOY were first found in the seine on June 12: This is later than the first L appearance of YOY in 2001 and 2002 in Plymouth Harbor.

On June 6 seine samplingvwas carried out at three additional sites in an effort to determine the degree of dispersal of hatchery fish. Hatchery fish were collected at the release site on that date, but were not found at any other station (Table 6). This may have resulted from a relatively low density of fish once dispersed from the release site.

Vigorous sampling over a wide area in the days immediately following release would i help further clarify this issue.

Size/Growth -

Hatchery-raised YOY winter flounder averaged 34 mm (s.e. = 0.5, n = 133) at release. Growth of hatchery fish was rapid, 0.82 mm/day (p = 0.0000, R2 = 0.97) from U May 15 to August 6 based on linear regression analysis (Figure 6). Growth slowed somewhat later in the season, to 0.43 mm/day from September 16 to September 30. One hatchery fish was recaptured on September 30 measuring 106 mm. Wild YOY were about half that size on that date, averaging 51 mm total length.

Wild YOY winter flounder grew at the rate of 0.21 mm/day (p = 0.02, R2 = 0.44) from June 12 to August 6, a slower rate compared to hatchery fish (growth rate = 0.78 mm/day for June 12 to August 6). That represented a conservative estimate of the growth rate of wild YOY winter flounder since the protracted settling period of age-0 wild winter flounder results in small newly recruited fish being averaged with larger previously settled fish, reducing the overall average, and therefore the estimated growth rate.

L MarineResearch, Inc.

9 Hatchery and wild YOY overlapped in size range on three sampling dates in 2003; June 12, June 17, and July 9. However, throughout the study, mean total length of hatchery fish exceeded wild fish, ranging from 55-124% larger than wild YOY (Figure 6).

Age 1 wild winter flounder were caught from May 15 to September 16, 2003. Age 1 flounder grew at the rate of 0.67 mm/day from May 15 to August 6, slightly slower than hatchery fish over the same growth period.

2004 Abundance/density A total of 312 tagged hatchery winter flounder were collected in 17 sampling events during the 2004 beach seine survey (Table 8). 91% of the recovered hatchery fish were caught within 60 days of release. The remaining 9% were recaptured 72 to 172 days after release. The decrease in recaptures over time probably reflects a combination of mortality and dispersal.,

A total of 2,108 wild winter flounder were collected in the 2004 beach seine survey. Of the total, 1,692 were young-of-the-year (age-0) and 416 were age 1 or 2 (Tables 8,:9). In the initial seine collections (May 10 - June 3) only age one and two wild winter flounder were collected; wild young-of-the-year (YOY) were not found in the seine until June 7. This is later than the first appearance of YOY in Plymouth Harbor in 2001 and 2002, but slightly earlier than their appearance in 2003.

"On May 13 seine sampling was carried out at four additional sites in an effort to determine the degree of early dispersal of hatchery fish. Hatchery fish (n = 13) were collected at the release site and at Site 3 (n = 3) on that date (Table 8), showing limited dispersal. This result is consistent with the findings of Saucenman and Deegan (1991) which indicated minimum lateral and cross-channel movement of YOY winter flounder.

Size/Growth Hatchery-raised YOY winter flounder averaged 29, mm (s.e. = 0.5, n 92) at release between May 10 and May 12. Growth of hatchery fish was most rapid from May 13 to July 6, 0.64 mm/day (p = 0.00001, R2 = 0.97). It then slowed to 0.44 mm/day (p 0.04 ; R 0.92) from July 6 to September 2 based on linear regression analysis (Figure 7).

Wild YOY winter flounder appeared to grow at a much slower rate over the corresponding July 6 to September 2 period - 0.09 nmm/day and in ' fact the slope of the growth line was not significantly different from zero (p = 0.18). As indicated for 2003 those rates are likely biased by the continual influx of younger fish during the protracted settlement period.; Examining grow using only the 5 0 th,and 75h percentile lengths on each sampling date in an effort to focus on the largest fish in'the collections resulted in greater apparent growth (0.11 and 0416 mm/day, respectively) but slope parameters were not significantly different from zero.

'Age 1 wild winter flounder were caught from May. 10 to, October 1, 2004. Age 1 flounder grew at the rate of 0.88 mm/day (p = 0.00001, R -0.95) from May 10 to July 6.

Growth rate slowed to 0.24 mm/day (p 0.07, R2 = 0.86) from July 6 to August 18.

Only 1 Age 1+ flounder was collected after August 18, therefore further growth rates were unable to be calculated.

Marine Research, Inc.

10 Stomach Content Analysis 2001 A total of 37 young-of-the-year winter flounder were examined for stomach content analysis including 17 individuals from hatchery stock. None of the stomachs were empty. In general the diet of these fish consisted of a variety of juvenile infaunal and epibenthic species. Polychaete worms were the dominant food item generally comprising 50% or more of the gut contents. Bivalve mollusks and crustacea were also commonly eaten. A wide range of crustacean types were found including copepods, cumacea, ostracods, capellid and gammarid amphipods, and decapod larvae. No  :

indication of selectivity was noted. No remarkable differences in stomach contents were noted between hatchery fish and wild individuals nor between those marked and unmarked recovered from the holding pens and the seine. -

'2002 A total of 39 young-of-the-year winter flounder were examined for stomach content analysis including 16 individuals from hatchery stock and 23 wild fish. Five of L

the individuals examined had empty stomachs, four were wild fish. In general, the diet of these fish consisted of a variety of juvenile infaunal and epibenthic species as noted in l 2001. Polychaetes constituted the dominant food type consumed by tagged flounder averaging 24% of the volume of material in each gut (Table 14). Unidentifiable insect larvae remains followed accounting for 21%, and unidentified animal remains ranked third at 17%. Other prey items included terrestrial seeds, and a variety of crustaceans.

L Gut contents of wild fish were examined from the same dates at approximately the same lengths as tagged fish. Crustaceans formed the dominant prey type for wild fish accounting for an average of 57% of the volume followed by polychaete remains (23%)

L and polypoid cnidarin larvae (7%). A wide range of crustacean types were found including copepods, isopods, ostracods, amphipods, and decapod larvae.

The primary prey found in the guts of hatchery and wild winter flounder changed L

over time (Table 15). Given the small number of hatchery guts available for examination, and the absence of concurrent prey abundance data it is difficult to determine if this change represented a change in prey availability or prey choice. Overall, no indication of L

selectivity was noted consistent'with 2001 results. L 2003 Gut contents were examined for 37 hatchery YOY winter flounder and 26 wild YOY winter flounder captured in the seine. Two of the hatchery fish examined had empty stomachs. Stomach contents of hatchery fish caught in the seine from May 28 to L

June 17 were dominated by annelids (mostly polychaetes), averaging 91% of the'contents over that time (Table 16). Hatchery fish had a more mixed gut composition from July 3 U

to the last sampling date on September 30, perhaps reflecting a change in prey availability or improved foraging ability with age and increasing size. Stomach contents of wild YOY winter flounder caught in the seine were also strongly'dominated by L annelids on June 17 (85% of the gut contents). Gut contents thereafter were more mixed in composition similar to hatchery fish. When averaged for the period during which both hatchery and wild YOY winter flounder co-occurred, gut contents were relatively similar (Table 17). For hatchery YOY annelids made up the majority of the prey species, L

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11 followed by arthropods, and others and mollusks. Wild YOY guts were mostly composed of annelids, others, arthropods, and mollusks.

2004 Gut contents were examined for 60 hatchery YOY winter flounder, 24 wild YOY, and 34 Age 1+ winter flounder captured in the seine. There were no empty stomachs.

Stomach contents of recaptured hatchery fish from May 11 to June 3 were dominated by annelids, averaging 76.5% of the contents over that time (Table 18). Stomach contents of hatchery fish contained a more mixed composition from June 18 to the last sampling date of September 16. Stomach contents of wild Age 1+ captured from May 10 to June 3 were also dominated by annelids (72.4%). Wild YOY stomach contents from June 18 to September 16 contained a mixed composition (Table 18). Gut contents averaged for the period during which both hatchery and wild winter flounder co-occurred were relatively similar (Table 19). Hatchery flounder prey species were dominated by annelids, followed by others, and then arthropods. Wild winter flounder were dominated by annelids, followed by arthropods, others, and then mollusks.

Pen Studies 2001 The temporary holding pen set overnight during the Plymouth Harbor release on June 4 failed due to abrasion between the nylon mesh and the posts used to secure it. Of the 50 hatchery fish released into the pen, 13 (26%) were recovered alive, 4 were found dead, the remainder apparently escaped through tears in the sidewall of the pen. Of the 18 wild flounder released, 5 (28%) were recovered alive and 1 was found dead. In an effort to offer natural bottom to the fish and help anchor the pen, coarse sediment was added before the fish were released. The sediment proved troublesome when trying to recover the fish since individuals were'difficult to find. It is also likely that some fish were injured as the pen was moved to shallow water for recovery since gravel in the sediment rolled around in the pen.

The wire and plastic mesh pens set on June 19 were hauled on three different dates (Table 10).- One pen contained approximately 200 marked fish intended for use in holding pens in Duxbury Bay. -This pen, set in shallow water, was hauled on June 22 only three days after it was set. The number of marked fish, found in the pen was surprisingly low; 24 were recovered alive along with 3 partial flounder. Not only were 88% of the fish no longer alive but also all except three were missing. Small sevenspine bay shrimp (Crangon septemspinosa) and several periwinkles (Littorinaspp.) were found in the' pen and it is possible they consumed the flounder. The periwinkles apparently originated from two rocks used to weight the pen and the shrimp were small enough to move freely through the mesh. Whether they consumed the flounder before or after they died is unknown. Bay shrimp are known to prey on young winter flounder from the time they metamorphose to approximately 20 mm (Witting and Able 1993, 1995). Whilethe mean length of fish placed in the pen'exceeded 20 mm, being confined could have increased their susceptibility to predation.

The second pen set in shallow' water was retrieved on June 29, 10 days after it was set. Survival among marked individuals was 67% compared with 11% among wild Marine Research, Inc.

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flounder. Subsequently, two pens were retrieved on July 10, 21 days after being set.

Survival of marked fish averaged 61% and survival of wild fish averaged 20%. The remaining three pens were retrieved on August 2, 44 days after being set. Survival of marked hatchery fish averaged 29% compared with 43% among wild fish. L The pens employed in Duxbury Bay were found to be unsatisfactory in design.

Additionally, pen location was unsuitable given the large number of people in close proximity to the experimental area and the strong currents found there. When the pens '

were recovered to check for survivors, they were found opened,'flipped over, and one had holes in the mesh allowing fish to escape. No fish were recovered from the pens. These pens were not used after these experiment failures.

2002 The wire and plastic mesh pens set on the 13th of June were hauled on- three, different dates (Table 11). Two pens were recovered on each of the following dates: July 15, 33 days after deployment; August 13, 62 days after deployment; and August 26, 75 ¶ days post-deployment. One of the pens was not recovered because its marker buoy was, lost.

Recovery of marked and wild winter flounder juveniles from the pens was low.

Of the 90 marked fish placed in retrieved pens, only 3 were recovered. Of the 90 wild fish placed in the six pens, 4 were recovered. In three of the pens, no flounder were recovered. Low survival in the pens may be due to several factors. First, recovered pens were heavily fouled by the accumulation of settling organisms on the pen's top and sides L (Figure 8). This accumulation restricted water flow through the pens and could have resulted in mortality if water became stagnant particularly at slack tide, leading to hypoxic conditions. Another source of loss may have resulted from predation within the L

pens. Several pens contained crabs, shrimp, and other fish species. These animals apparently entered through the mesh as larvae or early stage juveniles and grew to considerable size within the pen. Careful scrutiny of each pen failed to indicate any other way for the predators to have entered other than through the mesh. The flounder in the pens were probably consumed, being more susceptible to predation by confinement. One l pen contained 8 green crabs (Carcinus maenas), 1 hermit crab (Pagurus longicarpus),

and 2 cunner (Tautogolabrus adspersus). Another pen held 6 spider crabs (Libinia spp.),

5 green crabs, and 2 cunner approximately 50 mm total length. The largest crab was 48 mm carapace length. Green crabs are a known predator of YOY winter flounder (Fairchild and Howell 2000).

2003 A major advantage of the new pens employed in the 2003 study was accessibility over the course of the study. Since the pens were set in relatively shallow water they could be examined on spring tide days when the covers were exposed, allowing fish to be recaptured, measured, and moved to a clean pen. Moving the fish was particularly important because the pens fouled quickly, reducing water flow through the mesh. Low L water turnover can limit the oxygen available to flounder during slack tides and may reduce prey abundance by decreasing the settlement of benthic organisms. Additionally, moving the fish to pens over 'fresh' sediment probably prevented the flounder from L consuming all of the prey resources within the confined area.

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13 A disadvantage to this new design was that the removal of all other fish and large invertebrates proved difficult at the start of each trial even though pens were vigorously cleaned. Invertebrate predators (large crabs) and other fish, including wild YOY winter flounder, were found in some pens (Table 20). The predation or competition of other organisms in the pens may have negatively impacted flounder survival.

Survival results Survival of hatchery flounder in the new pens employed in 2003 was the highest to date, with fish being successfully maintained in pens from May 20 (the second release date) until September 30, a total of 134 days. The first two experiments were short in duration, where 50 fish were placed in a pen on the first and second release date to determine short-term survival and the effects of transfer and release of the hatchery fish to the Harbor. In the absence of predators, 24-hour survival rates for these experiments were 90% on May 15 and 100% on May 20, indicating that hatchery fish successfully survived the transition to the wild (Table 12).

Survival of hatchery fish in long-term pen experiments varied over time (Table 12). The first experiment conducted from 5/20-6/17 had a relatively low 29-day survival rate (50%) compared to experiments conducted from 6/17-7/16 and 7/15-8/13. The low survival observed in -the first experiment is probably the result of overstocking in a smaller pen, where 10 fish were placed in a 3 ft by 3 ft pen. This may have resulted in some density-dependent effects such as food resource shortage. All other experiments were conducted in 4 ft by 3 ft pens. The average survival of hatchery flounder in pens from 6/17-7/16 was 63% (range 40-80%). Those fish that survived to July 16 (day 26-

28) were transferred to clean pens and had a high 30-day survival rate, averaging 90%.

The survival rate of tagged fish in the experiments conducted from 8/13-9/30 was 70%.

The increase in survival from the 6/17-7/15 experiments compared to the later experiments (63% vs. 90% for 7/15-8/13 and 70% for 8/13-9/30) suggests that fish that survived the first month of release have a greater likelihood of continued survival.

Cumulatively, survival for one experiment conducted for 86 days was 40% and averaged 52% for the five experiments set up on June 19 ending 55-56 days later on August 12 and 13 (Table 12).--

Although efforts were made to remove predators and other fish from the pens at setup, invertebrate predators and other fish were found in some pens (Table 20). The two experiments (LT#2 and LT#6) which had large crabs (>65mm carapace width), wild YOY winter flounder, and other finfish had the lowest survival for the 6/19-7/14 period, with only 40% of the hatchery fish surviving over that time. The 'survival in LT#4 was comparatively low at 60% from 6/19-7/14 although no predators were found in the pen.

With the exception of LT#4, it is likely that predation or competition were responsible for the experiments with the lowest observed survival.

Growth Rate Growth rate was-determined for the first caging experiment conducted from 5/20-6/17, the six experiments that took -place from 6117-8/13, and the two experiments conducted from 8/13-9/30. Focus was placed on comparing growth rate of caged hatchery fish with the uncaged hatchery population.

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14 The growth rate of experiment #1 conducted from 5/20-6/17 was 0.13 mm/day (Table 21). This growth rate was low compared to the 0.76 mm/day growth rate L

observed for hatchery fish recaptured in the' seine over the period of 5/15-6/17. The low growth rate observed in the first experiment is probably the result of overstocking in a smaller pen, where 10 fish were placed in 3-ft x 3-ft pen. This may have resulted in some L

density-dependent effects such as food resource shortage.

The average growth rate of caged hatchery fish from 6/17-8/13 was 0.43 mm/day (range 0.31-0.52 mm/day, s.e. = 0.03, Table 21). The growth rate of uncaged hatchery fish from 6/17-8/6 (no seine sampling was conducted on 8/13) was 0.74 mm/day. The average growth rate for experiments conducted from 8/13-9/30 was 0.13 mm/day (Table L 21).- This rate was significantly lower than that observed in cages from-6/17-8/13. The growth rate of hatchery fish collected in the seine from 8/6-9/30 was 0.19 mm/day (R2 =

0.88, p = 0.06). This rate was significantly less than that observed in the seine-collected L hatchery-fish from 6/17-8/6. 'Therefore, it is not surprising that the growth rate in the cages was reduced between these periods. Again, it is interesting to note that the growth rate of caged flounder was lower than that observed from seine-collected hatchery fish.

Gut Contents Gut contents were examined from 9 hatchery fish held in pens. The gut contents l of these fish were dominated by annelids (58.5% of total gut volume on August 13, and 44% of total gut volume on September 30). Other important taxa included arthropods, mollusks, chordates, and others (Table 16).

L 2004 Survival results The two 24-hr experiments were designed to determine short-term survival and the effects of transfer and release of the hatchery fish to Plymouth Harbor. In the absence of predators, 24-hour survival rates for these experiments were 90% on May 10 and L 100% on May 11, indicating that hatchery fish successfully survived transport and release (Table 13).

The long-term survival study successfully maintained fish in pens from May 12 L (the last release date) until September 2, for a total of 114 days. Survival of hatchery fish in the long-term experiment varied over time and between pens (Table 13). During the first month of the experiment (May 12 - June 7, 27 days) the survival rate was 90% and during the -second month (32 days) the survival rate was 84.5% with a cumulative survival rate of 80%. The monthly survival rates continued to hold at 84% or higher until September (Table 13). The 2004 monthly and cumulative survival rates were higher than the 2003 survival rates.

Growth Rate V Growth rates in the long-term survival study varied between pens and over time (Table 22). Growth rates from May 12 - July 5 (average: 0.44 mm/day) were notably greater in all six pens than the July 5-August 31 growth rates (average: 0.14 mm/day, Table 21). The growth rates of caged hatchery flounder where lower than the growth rates of hatchery fish collected in the seine from May 12- July 5 (0.64 mm/day) and July 5-August 31 (0.46 mm/day, Table 22). The 2004 average growth rates were very similar to the 2003 average growth rates. Growth rates may have been affected by the presence

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15 of anoxic conditions from July until the end of the experiment (Table 23). The pen bottoms and surrounding area sediment (deeper than a cm) was black, fine, and silty during this period. The pens denoted as anoxic in Table 23 had the sediment described above accompanied by a hydrogen sulfide smell.

Although pens were thoroughly cleared at the beginning of each trial some crabs and wild YOY winter flounder were found in them at the end (Table 23). No discernible effects on the survival and growth rates of the hatchery-reared flounder were observed with the presence of the crabs and wild YOY winter flounder in the pens.

Gut Contents Gut contents were examined from 6 hatchery fish held in pens. The gut contents of these fish were dominated by annelids, 60% of the total stomach volume. The next dominate group was others, followed by arthropods, and mollusks (Table 18).

Discussion:

The scale of the hatchery release provides a useful perspective when evaluating recapture rates particularly those in 2000 and 2001. The area of Plymouth Harbor is approximately 3,824 acres or 15,475,177 m2 (Frank Germano, Massachusetts Division of Marine Fisheries, personal communication). If 15,000 or 25,000 young flounder were released and dispersed evenly over 10% of the Harbor bottom, 1 to 1.6 individuals would be expected every 100 m2. Since fish typically demonstrate a contagious or patchy rather than a uniform distribution, it becomes clear that hatchery fish released may be difficult to find' once they disperse. An individual recaptured on August 1, 2003 nearly a mile from the release site, indicated that individuals may disperse over a wide area.

The recapture rate in Plymouth Harbor was similar in 2001 and 2002 (0.12 and 0.13% respectively). The rate increased in 2003, when 144 hatchery fish were recaptured (0.5 8%), and again in 2004, when 312 hatchery fish were recaptured (1.2%), representing large increases in recapture rates compared to previous years. The increased numbers of recaptured hatchery fish with each succeeding year is probably due to a combination of factors but release date was likely important since number of recaptures and initial release date were negatively'correlated. The particularly early release dates in 2003 and 2004 (May 15, 2003; May 10, 2004) may have been beneficial to introduced fish due to the relatively low predator abundance observed in the initial seine collections and the lack of wild YOY winter flounder, reducing intraspecific' competition for resources.

Wild YOY winter flounder were not collected in seine hauls until June 12, 2003 and June 7, 2004, 23 to 28 days after hatchery'release. The somewhat later first appearance of wild YOY winter flounder 'in Plymouth'Harbor in 2003 and 2004, compared to 2001 and 2002 can be explained by colder spring water temperatures (Figure 9). Sogard et al.

(2001) found that colder temperatures' delayed winter flounder larvae occurrence which resulted in corresponding later metamorphosis and settlement. In Plymouth Harbor delayed winter flounder settlement would result in the delayed arrival of wild YOY at sampling locations.

To take advantage 'of reduced predation and intraspecific competition continued early release may be a good strategic measure. However, it is important to consider that prey resource availability for newly released YOY winter flounder may vary in abundance and timing from year to year. Selecting release dates should consider both Marine Research, Inc.

16 predator abundance and prey abundance. Further study of these relationships (release date, prey abundance, predator' abundance, and intraspecific competition) would be L

helpful in defining the best time for release.

Growth'rates-calculated for hatchery-reared flounder collected in the seine for 2002 to 2004 were higher than the growth rates for wild YOY flounder during the same period. The difference in growth rates may be explained by the protracted settling period of age-0 wild winter flounder. Small newly'recruited fish are averaged with larger previously settled fish, reducing the overall average, and therefore the estimated growth rate. Larval winter flounder were collected at PNPS as late as July 4, 2003 and July 9, 2004 suggesting that wild YOY may continue to join the wild population for a very long time.

The stomach contents from 2001-2004 were similar across years and between hatchery and wild YOY winter flounder. The diets'consisted infaunal and epibenthic species. Plymouth Harbor young winter of a variety of juvenile flounder appeared to be opportunists feeding upon a wide array of prey items within a suitable size range for their small mouths. This is consistent with information from the literature Mulkana 1966, Klien-MacPhee 1978, Armstrong 1995, Stehlik and Meise 2000). (Pearcy 1962, Stehlik and Meise (2000) found a pronounced dietary shift occurred from calanoid copepods to a wider array of prey items when young winter flounder reached around 50 mm in'length consistent with our results.

The winter flounder growth rates observed in the pens in 2003 and 2004 (Tables 21, 22) are comparable to those observed in similar pens in Rhode Island estuaries.

Meng et al. (2000) reported mean growth rates of YOY winter flounder ranging from 0.32-0.43 mm/day based on experiments conducted from June 4 to July 7, 1997. The pen experiments conducted in 2003 found cumulative survival of hatchery fish penned for 55+ days ranged from 40 to 80%, averaging 52%. The long-term experiment conducted in 2004 found a cumulative survival of hatchery fish penned for 55+ days ranged from 40 to 100%, averaging 80%, and cumulative survival for 112+ days ranged from 40 to 80%,

averaging 64%.

The. lower growth rate observed in the 2003 and 2004 long-term pen survival experiments compared to the growth rates of the uncaged hatchery fish (Tables 21, 22) suggested that the caged flounder did not have an optimal habitat for development.

While pens may eliminate sources of stress and mortality from predation by piscivores (striped bass, bluefish, cormorants and shore birds), they also limit access to food resources and reduce water exchange potentially decreasing dissolved oxygen, 'and increasing metabolic wastes. Caged fish may experience suboptimal feeding since they are unable to move to microhabitats that have higher food concentrations. In addition, fouling on the pens could restrict both the recruitment of settling food resources and their survival. These factors may be compounded by increases in water temperature near to the upper lethal temperature for winter flounder, 300 C (Pearcy experiments have indicated that winter flounder growth can be 1962). Previous caging inhibited by increasing water temperatures and low oxygen levels in shallow waters during et al. 2001, Sogard 1992, Phelan et al. 2000). Olla et mid-summer (Sogard al (1969) observed that water L

temperatures higher than 22.20C caused winter flounder to bury into the sediment and cease to feed. In spite of these limitations, the pens provided survival information by eliminating dispersion and advection.

valuable growth and l Marine Research, Inc.

U

17 Conclusions Young-of-the-year winter flounder reared in the Chatham hatchery were easily transported to both Plymouth Harbor and Duxbury Bay at high densities. Post-release collections from 2001-2004 indicated that released fish do survive and grow particularly when released early in the season. The 2001 seine trials where hatchery fish were released in the path of the seine suggested that recently handled hatchery fish behave differently from undisturbed fish. They appear to settle to the bottom where they remain inactive for a period of time and during that period they are less susceptible to capture than wild fish. The 2003 dispersal study where 1 tagged flounder was recaptured nearly a mile from the release site indicated that significant dispersal can occur. Dispersion and mortality among hatchery fish may account for absent or low recapture numbers, especially when wild YOY are found in seine collections. Size and growth analysis of uncaged hatchery-reared fish indicate that there was successful growth. Stomach content analysis conducted in 2001 to 2004 suggested that there were not pronounced differences in hatchery fish feeding behavior compared to wild YOY winter flounder. This indicates that hatchery-reared fish successfully converted to wild food resources. The 2001, 2003 and 2004 pen studies further support this.

Pen studies may eliminate some sources of mortality such as predation, however, they may introduce others in the form of reduced water exchange and food resources.

These factors were reflected in reduced growth among caged fish relative to free-ranging hatchery fish. In spite of the limitations, pens do provide valuable growth and survival information by eliminating dispersion and advection. Pen studies strongly suggested that the survival rate is greater than the rate determined by seining. Assuming all hatchery fish adjusted quickly to being released, as the 2003 and 2004 pen studies suggested, survival among hatchery and wild fish is likely to be similar.

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18 Literature Cited Armstrong, M. P. 1995. A comparative study of the ecology of smooth flounder, Pleuronectesputnami, and winter flounder, Pleuronectesamericanus, from Great Bay Estuary, New Hampshire. Ph. D. Dissertation, University Of New Hampshire, Durham, L New Hampshire.

Klein-MacPhee, G. 1978. Synopsis of biological data for the winter flounder, Pseudopleuronectesameicanus(Walbaum). FAO Fisheries Synopsis No. 117. 43 pp.

Meng, L., C. Gray, B. Taplin, and E. Kupcha. 2000. Using winter flounder growth rates to assess habitat quality in Rhode Island's coastal lagoons. Marine Ecology Progress :5 Series 201: 287-299. -

Mulkana, M. S. 1966. The growth and feeding habits of juvenile fishes in two Rhode Island estuaries. Gulf Research Report 2: 97-167. -

Q11a, B. L., R. Wicklund, and S. Wilk. 1969. Behavior of winter flounder in a natural habitat. Trans. Am. Fish. Soc. 4: 717-720.

Pearcy, W. G. 1962. Ecology of an estuarine population of winter flounder, Pleuronectes americanus (Walbaum). Bulletin of the Bingham Oceanographic Collec-tion, Yale University 18(1).

U Plelan, B. A., R. Goldberg, A. J. Bejda, J. Pereira, S. Hagan, P. Clark, A. L. Studholme, A. Caslabrese, and K. W. Able. 2000. Estuarine and habitat-related differences in L

growth rates of young-of-the-year winter flounder (Pseudopleuronectesamericanus)and tautog (Tautoga onitis) in three northeastern US estuaries. J. Exp. Mar. Biol. Ecol. 247:

1-28.

L Saucerman, S. E., and L. A. Deegan. 1991. Lateral and cross-channel movement of L young-of-the-year winter flounder (Pseudopleuronectesamericanus) in Waquoit Bay, Massachusetts. Estuaries 14: 440-446. U Sogard, S. M. 1992. Variability on growth rates of juvenile fishes in different estuarine habitats. Mar. Ecol. Prog. Ser. 85: 35-53. L Sogard, S. M., K. W. Able, and S. M. Hagan. 2001. Long-term assessment of settlement and growth of juvenile winter flounder (Pseudopleuronectesamericanus) in New Jersey estuaries. Journal of Sea Research 45: 189-204.

Stehlik, L. L. and C. J. Meise. 2000. Diet of winter flounder in a New Jersey estuary:

Ontogenetic change and spatial variation. Estuaries 23(3): 381-391.

Witting, D. A. and K. W. Able. 1993. Effects of body size on probability of predation for juvenile summer and winter flounder based on laboratory experiments. Fish. Bull., U. S.

91: 577-581.

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19 Witting, D. A. and K. W. Able. 1995. Predation by sevenspine bay shrimp Crangon septemspinosa on winter flounder Pleuronectesamericanusduring settlement: laboratory experiments. Mar. Ecol. Prog. Ser. 123: 23-31.

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20 Figure 1. Plymouth Harbor release site.

Figure 2. Duxbury Bay release site. L L

21 Figure 3. Tagged hatchery winter flounder, left: green tag = 2003 and right: orange tag = 2004.

Note the left-eyed variant from the 2004 hatchery stock on the right.

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!Benjamin;,

Figure 4. Open-bottom pens employed in 2003 and 2004 growth and survival experiments.

22 U 2002 YOY Winter Flounder Growth L 100 0 hatchery E s I 01 ,V .....

46 -

~L Figure 5. Size of hatchery and wild YOY winter flounder over time, Plymouth Harbor, 2002. Bars represent range (min-max) of size and point represents mean.

L 2003 YOY Winter Flounder Growth 1201 0 hatchery E -e1wild rJ 0 0 180 NL 40 -I C .

o 20 0

Figure 6. Size of hatchery and wild YOY winter flounder over time, l Plymouth Harbor, 2003. Bars represent range (min-max) of size and point represents mean. I

23 2004 YOY Winter Flounder Growth 120 -

o hatchery I

. 6 100 - S wild i E- I o IIM 80 -

1 IM 1C i13 60 -

0 'I 1 .

i-a 40 - +d040;:!'f i1C0 120 20 -

0 - I I I I I I I I I I l I I 0~k4Z N clFN O Figure 7. Size of hatchery and wild YOY winter flounder over time, Plymouth Harbor, 2004. Bars represent range (min-max) of size and point represents mean.

Figure 8. Enclosed pen used in 2002 growth and survival studies showing fouling.

24 L 12 Cape Cod Bay Water Temperature L

6 ,. s I L1 i4 -- 2000 l- 2001 1 2 - 2002 I I- 2003

--- 2004 Figure 9. Cape Cod Bay water temperature 2000-2004 at 40-ft depth strata.

Coastal Lobster Project of the Massachusetts Division of Marine Fisheries, Rocky Point.

L i

I

h 6

6

s> r r. £1, r7>- e -u yr r a r rV 25 Table 1. Release details for 2000-2004 PNPS winter flounder stock enhancement program.

average average date ft of hatchery size (mm) of hatchery size (mm) of wild water Year of release fish released fish at release I yoy winter flounder ' release location temperature (0C) 2000 7/24 4,700 28.1 (0.7) Plymouth Yacht Club 19.3 7/28 10,600 29.9 (0.5) West side of Plymouth Beach 17.9 7/31 50.1 (1.9) total 15,300 2001 6/4-6/5 4,950 29.7 (1.1) 26.9 (2.2) Plymouth Yacht Club 15.4 6/12 1,000 Duxbury Bay 6/14 8,000 28.4 (0.9) Duxbury Bay 23.0 6/15 37.2 (1.1) total 13,950 2002 5/31 15,000 16.5 6/4 10,200 28.0 (1.6) Plymouth Yacht Club 15.4 6/13 32.6 (05) 31.0 (0.6) Plymouth Yacht Club total 25,200 2003 5/15 16,000 34.0 (0.8) no wild yoy at release Plymouth Yacht Club 16.0 5/20 9,000 33.0(0.9) no wild yoy at release Plymouth Yacht Club 14.0 total 25,000 2004 5/10 9,900 29.9 (0.4) no wild yoy at release Plymouth Yacht Club 14.0 5/11 10,100 28.39 (0.8) no wild yoy at release Plymouth Yacht Club 15.0 5/12 5,000 no wild yoy at release Plymouth Yacht Club 15.4 total 25,000 I The standard error is denoted in parentheses.

26 Table 2. Post-Release Sampling of Young-of-the-Year Flounder - 2000 number of surface number of age-0 Sampling date Location Gear hauls/tows water temp winter flounder collectec mean size (mm) s.e. n range (mm) 7/31 Plymouth Yacht Club, 50-ft beach seine 7 184 wild 50 1.9 51 33-87 8/4 Plymouth Yacht Club 50-ft beach seine 7 22 wild 48 2.1 22 34-67 beam trawl 7 19 wild 56 2.5 19 34-75 8/11 Plymouth Yacht Club 50-ft beach seine 7 267 wild 51 1.4 50 36-74 beam trawl 8 22.4 36 wild 55 2.5 36 36-90 8/18 Plymouth Yacht Club 50-ft beach seine 12 19.8 95 wild 58 2.0 50 40-97 beam trawl 14 19.2 14 wild 61 4.8 14 38-102 8/25 PlymouthYacht Club 50-ft beach seine 9 21.7 66 wild 57 2.1 50 38-100 beamtrawl 9 19.5 14wild 69 6.2 14 43-131 9/1 Plymouth Yacht Club 50-ft beach seine 7 17.6 238 wild 61 1.6 50 45-95 9/8 Plymouth Yacht Club 50-ft beach seine 13 18.0 237 wild 63 1.8 50 39-102 beam trawl 3 11 wild 65 4.3 11 45-96 9/18 Plymouth Yacht Club 50-ft beach seine 14 16.0 74 wild 60 1.3 50 44-96 beam trawl 2 3 wild 64 3.5 2 60-67 9/22 Plymouth Yacht Club 50-ft beach seine 13 17.1 112 wild 68 1.8 50 47-104 10/2 Plymouth Yacht Club 50-ft beach seine 16 14.2 135 wild 63, 1.2 81 46-95 beam trawl 3 10 wild 10/10 Plymouth Yacht Club 50-ft beach seine 11 13.2 7 wild 10/18 Plymouth Yacht Club 50-ft beach seine 12 12.7 19 wild 65 2.0 17 55-88 W7-_ r-I r-7 r-, r--I.I r-" r--,*. WI-n 9-1 r-n 4r-.. r' r-- U- r-- t-. F-. I-_

A:Alty d r> £i 1: IEl r> C: r Fr r 27 Table 2. Continued number of surface number of age-0 Sampling date Location Gear hauls/tows water temp winter flounder collectec mean size (mm) s.e. n range (mm) 11/1 Plymouth Yacht Club 50-ft beach seine 9 7.7 120 wild 68 1.4 34 55-85 11/3 Plymouth Yacht Club 50-ft beach seine 11 7.6 46 wild 78 2.0 44 52-101 11/9 Plymouth Yacht Club 50-ft beach seine

• 7.1 101 wild 71 1.9 50 46-98 11/16 Plymouth Yacht Club 50-ft beach seine

• 6.8 57 wild 72 2.6 50 48-115

• long hauls completed to cover similar portions of beach as on earlier dates Table 3. Plymouth Harbor Post-Release Sampling Young-of-the-Year Winter Flounder - 2001 number of surface number of age-0 Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/5 Plymouth Yacht Club 50-ft beach seine 6 15.6 46 wild 27 2.2 29 20-36 6/18 Plymouth Yacht Club I00-ft beach seine 4 228 wild 30 0.5 64 24-47 4 hatchery 36 0.4 4 35-37 6/29 Plymouth Yacht Club 100-ft beach seine 4 22.2 154 wild 39 0.4 145 24-50 7/10 Plymouth Yacht Club I00-ft beach seine 7 23.2 215 wild 39 0.7 132 27-67 8/2 Plymouth Yacht Club 100-ft beach seine 3 160 wild 43 1.1 64 30-68 1 hatchery 78 8/22 Plymouth Yacht Club 100-ft beach seine 5 59 wild 51 1.6 47 36-82 9/7 Plymouth Yacht Club 100-ft beach seine 7 96 wild 52 1.4 70 38-85 1 hatchery 88

28 Table 3. Plymouth Harbor Post-Release Sampling Young-of-the-Year Winter Flounder - 2001 number of surface .number of age-0 Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/5 Plymouth Yacht Club 50-ft beach seine 6 15.6 46 wild 27 2.2 29 20-36 6/18 Plymouth Yacht Club 100-ft beach seine 4 228 wild 30 0.5 64 2447 4 hatchery 36 0.4 4 35-37 6/29 Plymouth Yacht Club 100-ft beach seine 4 22.2 154 wild 39 0.4 145 24-50 7/10 Plymouth Yacht Club 100-ft beach seine 7 23.2 215 wild 39 0.7 132 27-67 8/2 Plymouth Yacht Club I00-ft beach seine 3 160 wild 43 1.1 64 30-68 1 hatchery 78 8/22 Plymouth Yacht Club 100-ft beach seine 5 59 wild 51 1.6 47 36-82 9/7 Plymouth Yacht Club 100-ft beach seine 7 96 wild 52 1.4 70 38-85 I hatchery 88 ff_~ r C- 111r71r__ rr_~ r__~ff- r-1 2111~ f~ r r_ I r- f_

r._ rc rr _

W -_, W ,.- W, - Ir- Ti U- W Z V r7. m - r>.- t. r . 3L 1I 29 Table 4. Duxbury Bay Post-Release Sampling Young-of-the-Year Winter Flounder - 2001 number of surface number of age-0 Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/15 Duxbury Bay 50-ft beach seine 7 25.1 43 wild 37 1.1 22 27-48 6/22 Duxbury Bay 100-ft beach seine 2 95 wild 41 1.0 60 24-60 6/27 Duxbury Bay 100-ft beach seine 10 55 wild 47 1.5 32 29-66 7/11 Duxbury Bay 100-ft beach seine 5 22.9 109 wild 46 1.0 103 25-75 1 hatchery 39 7/24 Duxbury Bay 100-ft beach seine 3 25.5 85 wild 48 1.6 67 30-80 9/20 Duxbury Bay 100-ft beach seine 2 38 wild 58 1.9 33 45-80

30 Table S. Post-Release Sampling Young-of-the-Year Winter Flounder - 2002 number of surface number of age-0 Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/4 Plymouth Yacht Club 100-ft beach seine 2 177 wild 28 1.6 6 24.35 18 hatchery 6/13 Plymouth Yacht Club 100-ft beach seine 3 14.0 261 wild 31 0.6 75 2246 6 hatchery 35 1.2 3 33-37 6/18 Plymouth Yacht Club 100-ft beach seine 4 38 wild 34 2.0 15 27-55 2 hatchery 37 7/2 Plymouth Yacht Club 100-ft beach seine 3 22.0 180 wild 34 1.0 63 21-54 2 hatchery 42 3.0 2 39-45 7/2 Site 2 100-ft beach seine 3 22.5 88 wild 36 1.2 60 21-66 7/15 Plymouth Yacht Club 100-ft beach seine 6 23.0 65 wild 42 1.7 65 25-96 7/30 Plymouth Yacht Club 100-ft beach seine 4 21.7 212 wild 45 1.8 50 29-78 2 hatchery 53 0.0 2 53 8/13 Plymouth Yacht Club 100-ft beach seine 5 23.0 95 wild 45 1.1 104 30-80 I hatchery 66 8/26 Plymouth Yacht Club 100-ft beach seine 4 19.5 34 wild 52 2.5 33 40-97 9/12 Plymouth Yacht Club 100-ft beach seine 5 17.5 79 wild 55 1.0 77 37-90 I hatchery 55 9/26 Plymouth Yacht Club 100-ft beach seine 5 17.0 .183 wild 61 1.5 62 42-98 10/3 Plymouth Yacht Club 100-ft beach seine 4 18.0 191 wild 61 1.1 50 47-85 aF V. -_- r- r- r-1 r- r i r-- r- C7 t r -- U r, r--r

r> 1 O f r r -_M '.l-w ; -Frat:

!t; F-a 31 Table 5. Continued number of surface number of age-O Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 10/10 Plymouth Yacht Club 100-ft beach seine 5 14.5 13 wild 65 2.6 13 43-84 10/17 Plymouth Yacht Club 100-ft beach seine 5 15.5 70 wild 60 1.3 50 45-80 10/30 Plymouth Yacht Club 100-ft beach seine 5 8.0 90 wild 64 1.8 30 42-87 11/12 Plymouth Yacht Club 100-fl beach seine 5 13.0 7 wild 73 3.4 7 60-85 11/26 Plymouth Yacht Club 100-ft beach seine 4 7.0 0 wild

32 Table 6. Post-Release Sampling Young-of-the-Year Winter Flounder - 2003 number of surface number of yoy Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 5/15 Plymouth Yacht Club 100-ft beach seine 2 16.0 0 wild 5/16 Plymouth Yacht Club 100-ft beach seine 3 10.5 0 wild 5/20 Plymouth Yacht Club 100-ft beach seine 5 14.0 0 wild 5/20 Site 2 100-ft beach seine 2 14.0 0 wild 5/21 Plymouth Yacht Club 100-ft beach seine 5 13.0 0 wild 5/28 Plymouth Yacht Club 100-ft beach seine 6 14.0 0 wild IIhatchery 44 1.5 11 37-52 6/4 Plymouth Yacht Club 100-ft beach seine 4 15.0 0 wild 3 hatchery 46 6.2 3 38-58 6/6 Plymouth Yacht Club 100-ft beach seine 2 16.0 0 wild 5 hatchery 48 4.1 5 33-56 6/6 Site 2 100-ft beach seine 2 0 wild 6/6 Site 3 100-ft beach seine 2 0 wild 6/6 Site 4 tO0-ft beach seine 1 0 wild 6/12 Plymouth Yacht Club 100-ft beach seine 5 18.0 10 wild 35 4.0 10 25-60 6/17 Plymouth Yacht Club 100-ft beach seine 6 16.0 42 wild 34 1.0 41 20-50 28 hatchery 60 1.3 28 43-75 6/18 Plymouth Yacht;Club 100-ft beach seine 3 15.0 10 wild 36 1.5 10 30-45 lOhatchery 63 1.5 10 57-70 la r--, # f=r rt=a_ ir fe a

ar r=

1-1

r_ t r Ir r WI 33 Table 6. Continued number of surface number of yoy Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/27 Plymouth Yacht Club 100-ft beach seine 5 20.0 13 wild 35 1.3 13 26-42 7/3 Plymouth Yacht Club 100-ft beach seine 5 18.0 114 wild 42 1.1 46 29-65 11 hatchery 76 1.2 9 72-81 7/9 Plymouth Yacht Club 100-ft beach seine 5 19.5 335 wild 49 1.2 49 30-70 33 hatchery 79 1.4 32 64-102 7/16 Plymouth Yacht Club 100-ft beach seine 5 19.0 205 wild 40 1.9 50 21-72 2 hatchery 89 3.0 2 86-92 7/23 Plymouth Yacht Club 100-ft beach seine 4 18.0 295 wild 48 1.8 48 25-72 8 hatchery 94 2.8 7 85-104 8/1 Plymouth Yacht Club 100-ft beach seine 3 18.0 279 wild 4 hatchery 98 5.4 4 86-112 8/1 Site 2 100-ftbeach seine 3 18.0 98 wild 47 1.3 98 15-78 1 hatchery 102 8/6 Plymouth Yacht Club 100-ft beach seine 4 18.0 284 wild 41 1.2 100 26-84 4 hatchery 92 3.7 4 85-102 9/2 Plymouth Yacht Club I 00-ft beach seine 4 17.5 509 wild 49 1.3 132 31-92 9/16 Plymouth Yacht Club 100-ft beach seine 5 20.0 290 wild 51 1.3 100 28-94 1 hatchery 100 9/30 Plymouth Yacht Club 100-ft beach seine 6 17.0 100 wild 51 2.0 78 35-139 I hatchery 106

34 Table 7. Post-Release Sampling Age-I Winter Flounder - 2003 number of surface number of age-I Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 5/15 Plymouth Yacht Club 100-ft beach seine 2 16.0 30 wild 75 2.6 30 47-108 5/16 Plymouth Yacht Club 100-ft beach seine 3 10.5 19 wild 78 2.3 19 64-97 5/20 Plymouth Yacht Club 100-ft beach seine 5 14.0 0 wild 5/20 Site 2 100-ft beach seine 2 14.0 19 wild 76 3.1 19 56-108 5/21 Plymouth Yacht Club 100-ft beach seine 5 13.0 0 wild 5/28 Plymouth Yacht Club 100-ft beach seine 6 14.0 4 wild 89 1.8 54 65-138 6/4 Plymouth Yacht Club 100-ft beach seine 4 15.0 6 wild 94 4.8 6 76-110 6/6 Plymouth Yacht Club 100-ft beach seine 2 16.0 3 wild 94 2.1 3 90-97 6/6 Site 2 100-ft beach seine 2 50 wild 90 67-125 6/6 Site 3 100-ft beach seine 2 0 wild 6/6 Site 4 100-ft beach seine 1 0 wild 6/12 Plymouth Yacht Club 100-ft beach seine 5 18.0 2 wild 110 10.5 2 99-120 6/17 Plymouth Yacht Club 100-ft beach seine 6 16.0 1 wild.1 99 2.0 88-110 6/18 Plymouth Yacht Club 100-ft beach seine 3 15.0 15 wild 104 2.5 15 85-124 6/27 Plymouth Yacht Club 100-ft beach seine 5 20.0 0 wild 7/3 Plymouth Yacht Club 100-ft beach seine 5 18.0 4 wild 118 3.5 4 110-125 V-_U7 977 - r-- t- - ,-I ur-"~V' r-- Vr7 trr- r- I(. (7 ITT I- 7

A r i 9 F FL) ' r5 ,r 1' wl- Or r Ur r. I W 35 Table 7. Contiiaued number of surface number of age-I Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 7/9 Plymouth Yacht Club 100-ft beach seine 5 19.5 1 wild 130 7/16 Plymouth Yacht Club 100-ft beach seine 5 19.0 0 wild 7/23 Plymouth Yacht Club 100-ft beach seine 4 18.0 6 wild 131 8.3 4 109-149 8/1 Plymouth Yacht Club 100-ft beach seine 3 18.0 3 wild 127 2.8 3 120-133 8/1 Site 2 100-ft beach seine 3 18.0 7 wild 118 4.5 7 103-133 8/6 Plymouth Yacht Club 100-ft beach seine 4 18.0 1 wild 129 9/2 Plymouth Yacht Club 100-ft beach seine 4 17.5 1 wild 140 9/16 Plymouth Yacht Club 100-ft beach seine 5 20.0 1 wild 145 9/30 Plymouth Yacht Club 100-ft beach seine 6 17.0 0 wild

36 Table 8. Post-Release Sampling Young-of-the-Year Winter Flounder - 2004 number of surface number of age-O Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 5/10 Plymouth Yacht Club 100-ft beach seine 2 14.0 0 wild 5/11 Plymouth Yacht Club 100-ft beach seine 14.0 0 wild 11 hatchery 30 2.1 11 20-44 5/12 Plymouth Yacht Club 100-ft beach seine 14.5 0 wild 5/13 Plymouth Yacht Club 100-ft beach seine 15.0 0 wild 13 hatchery 33 1.8 11 23-44 5/13 Plymouth Site 2 100-ft beach seine 15.0 0 wild 5/13 Plymouth Site 3 100-ft beach seine 15.0 0 wild 3 hatchery 36 4.4 3 27-41 5/13 Plymouth Site 4 100-ft beach seine 15.0 0 wild 5/13 Plymouth Site 5 100-ft beach seine 15.0 0 wild 5/19 Plymouth Yacht Club 100-ft beach seine 15.5 0 wild 5 hatchery 38 1.9 5 34-44 5/24 Plymouth Yacht Club 100-ft beach seine 14.5 0 wild 43 hatchery 43 0.7 43 30-53 6/3 Plymouth Yacht Club 100-ft beach seine 15.5 0 wild 48 hatchery 51 0.6 48 40-65

> 6/7 Plymouth Yacht Club 100-ft beach seine 14.5 5 wild 32 0.9 5 29-34 64 hatchery 54 0.7 64 41-65 6/18 Plymouth Yacht Club 100-ft beach seine 16.8 215 wild 34 0.5 99 23-44 43 hatchery 59 0.8 43 49-70 Ir_- C-7 V-7 r=., C-7i r-i r-111111 Ir-I W-1 r-I Irl-7 r.,-I W--7I V-1 [-,-- It= f-_-I W-7__ t-_-

IK r r r. cr:7. rd W r"- W r r- - r r- £ 37 Table 8. Continued number of surface number of age-0 Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) 6/23 Plymouth Yacht Club 1I00-ft beach seine 5 20.0 171 wild 33 0.7 100 ,22-52 31 hatchery 64 1.0 31 53-74 7/2 Plymouth Yacht Club 50-ft beach seine 19.0 42 wild 36 1.3 40 21-55 7 hatchery 65 1.2 7 60-70 7/6 Plymouth Yacht Club 100-ft beach seine 19.0 290 wild 35 0.7 104 21-54 17 hatchery 38 1.1 17 62-76 7/21 Plymouth Yacht Club 100-ft beach seine 25.0 184 wild 30 0.8 101 22-66 6 hatchery 82 2.4 6 74-90 8/3 Plymouth Yacht Club 100-ft beach seine 20.5 292 wild 39 1.5 100 24-77 11 hatchery 82 1.4 11 72-88 8/18 Plymouth Yacht Club 100-ft beach seine 20.0 185 wild 39 1.2 125 23-80 1 hatchery 93 93 9/2 Plymouth.Yacht Club 100-ft beach seine 18.0 80 wild 41 0.8 78 29-70 6 hatchery 96 1.1 6 92-100 9/16 Plymouth Yacht Club 100-ft beach seine 17.5 127 wild 49 1.3 101 34-90 2 hatchery 98 8.0 2 90-106 10/1 Plymouth Yacht Club 100-ft beach seine 16.5 23 wild 49 2.7 19 38-79 10/15 Plymouth Yacht Club 100-ft beach seine 14.0 50 wild 53 2.1 47 43-89 10/29 Plymouth Yacht Club 100-ft beach seine 11.0 20 wild 54 1.3 19 44-65 1 hatchery 90 11/18 Plymouth Yacht Club 100-ft beach seine 5 8.0 9 wild 52 4.4 9 41-80

38 Table 9. Post-Release Sampling Age-I Winter Flounder - 2004 number of surface number of age-I Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm) a* TV A A _ s PA Plymouth Yacht Club 100-ft beach seine 2 14.0

.. i 8.0 54-70

.. A 2 wild 62 5/10 2

- A s s j 5/11 Plymouth Yacht Club 100-ft beach seine 6 14.0 16 wild 63 1.6 16 54-75 5/12 Plymouth Yacht Club 100-ft beach seine 1 14.5 6 wild 64 3.3 6 50-75 5/13 Plymouth Yacht Club 100-ft beach seine 2 15.0 81 wild 69 1.2 42 56-85 5/13 Plymouth Site 2 100-ft beach seine 2 15.0 84 wild 5/13 Plymouth Site 3 100-ft beach seine 2 15.0 74 wild 67 0.9 67 51-85 5/13 Plymouth Site 4 100-ft beach seine 1 15.0 0 wild 5/13 Plymouth Site 5 100-ft beach seine 2 15.0 6 wild 68 3.4 6 58-82 5/19 Plymouth Yacht Club 100-ft beach seine 5 15.5 53 wild 70 1.2 52 55-94 5/24 Plymouth Yacht Club 100-ft beach seine 5 14.5 121 wild 72 0.8 97 60-98 6/3 Plymouth Yacht Club 100-ft beach seine 4 15.5 78 wild 81 1.1 78 55-110 6/7 Plymouth Yacht Club 100-ft beach seine 4 14.5 19 wild 82 1.9 18 68-98 6/18 Plymouth Yacht Club 100-ft beach seine 4 16.8 21 wild 91 1.8 21 70-102 6/23 Plymouth Yacht Club 100-ft beach seine 5 20.0 1 wild 109 7/2 Plymouth Yacht Club 50-ft beach seine 5 19.0 0 wild 7/6 Plymouth Yacht Club 100-ft beach seine 4 19.0 6 wild 113 7.4 6 92-141 7/21 Plymouth Yacht Club 100-ft beach seine 4 25.0 4 wild 113 3.0 4 106-119 a= ro c= r(7 v-= rrT r-rn r -Ii am

W~- r. -,U rr~ M K--' Ir af I F' K F I 39 Table 9. Post-Release Sampling Age-I Winter Flounder - 2004

,, m umber of surface number of age-I Sampling date Location Gear hauls water temp winter flounder collected mean size (mm) s.e. n range (mm)95-139 I 8/3 Plymouth Yacht Club 100-ft beach seine 4 20.5 2wild 117 22.0 2 8/18 Plymouth Yacht Club 100-ft beach seine 4 20.0 5 wild 123 2.6 5 115-130 9/2 Plymouth Yacht Club 100-ft beach seine 4 18.0 0 wild 9/16 Plymouth Yacht Club 100-ft beach seine 4 17.5 0 wild 10/1 Plymouth Yacht Club 100-ft beach seine 5 16.5 1 wild 135 10/15 Plymouth Yacht Club 100-ft beach seine 4 14.0 0 wild 10/29 Plymouth Yacht Club 100-ft beach seine 5 11.0 0 wild 11/18 Plymouth Yacht Club 100-ft beach seine 5 8.0 0 wild

40 Table 10. Summary of Pen Studies - 2001 Holding Period Number of tagged Number of wild Number of tagged Number of wild Experiment Date (days) age-O flounder introduced age-0 flounder introduced age-O flounder recovered age-0 flounder recovered LT#A 6/19-6/21 3 -200 0 24 (-12%)

LT#2 6/19-6/28 10 18 18 12 (67%) 2 (11%)

LT#3 6/19-7/9 21 18 18 10 (55%) 5 (28%)

LT#4 6/19-7/9 21 18 18 12 (67%) 2 (11%)

average survival 6/19-7/9 61% 20%

LT#5 6/19-8/1 44 18 18 8(44%) 13 (72%)

LT#6 6/19-8/1 44 18 18 8 (44%) 9 (50%)

LT#7 6/19-8/1 44 18 18 0(0%) 1 (6%)

average survival 29% 43%

Table 11. Summary of Pen Studies - 2002 Holding Period Number of tagged Number of wild Number of tagged Number of wild Experiment Date (days) age-f flounder introduced age-f flounder introduced age-f flounder recovered age-f flounder recovered LT#1 6/13-7/15 33 15 15 0 (0%) 2 (13%)

LT#2 6/13-7/15 33 15 15 2 (13%/6) 1 (7%)

average survival 7% 10%

LT#3 6/13-8/13 62 15 15 1 (7%) 1 (7%)

LT#4 6/13-8/13 62 15 15 0 (0%) 0 (0%)

average survival 4% 4%

LT#5 6/13-8/26 75 15 15 0 (0%) 0 (0%)

LT#6 6/13-8/26 75 15 15 0 (0%) 0 (0%)

LT#7 6/13 not recovered 15 15 average survival 0% 0%

r r.GC1 Or--, V a_ R t rim ram ri= n= rim r-

_ r_- . _ __ _ r-.--

r-7-- r!7- In r- r rC.. r-7 r . r r r vi I 41 Table 12. Summary of Pen Studies - 2003 Short-term experiments Experiment Holding period Number of tagged fish introduced Number of tagged fish recovered Survival (%)

ST#I 24hours- 50 45 90 ST#2 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 50 50 100 Long-term experiments Number of hatchery flounder Holding Cumulative holding Experiment Date Start- Finish period (days) Survival (%/6) period (days) Survival (%)

LT#I 5/20-6/17 10 5 29 50 LT#1 6/17-7/15 5 4 29 80 57 40 LT#2 6/19-7/14 5 2 26 40 LT#3 6/19-7/15 5 4 27 80 LT#4 6/19-7/14 5 3 26 60 LT#5 6/19-7/16 5 4* 28 80 LT#6 6/19-7/16 5 2 28 40 average 6/17-7/15 63.3 LT#I 7/15-8/13 4 4 30 100 86 40 LT#2 7/15-8/13 2 2 31 100 56 40 LT#3 7/15-8/15 4 3 32 75 58 60 LT#4 7114-8/12 3 2 30 67 55 40 LT#5 7116-8112 4 4 30 100 55 80 LT#6 7116-8/12 2 2 30 100 55 40 average 7/1548/13 90.3 cumulative average** 6/194/13 52.0 LT#7 8113-9130 5 4 49 80 LT#8 8/13-9/30 5 3 49 60 average 8/13-9/30 70.0

• I fish lost while measuring

• • average of experiments 2-6

42 Table 13. Summary of Pen Studies - 2004 Short-term experiments Experiment Holding period Number of tagged fish Introduced Number of tagged fish recovered Survival (%)

ST#I 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 50 45 90 ST#2 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 50 50 100 Long-term experiment Number of hatchery flounder Holding Cumulative holding Cumulative Experiment Date Start Finish period (days) Survival (%) period (days) Survival (%)

Pen #1 I 5112-613 5 4 23 80 Pen #2 5112-6/3 5 5 23 100 Pen #3 5/12-6/4 5 5 24 100 Pen #4 5/12-6/7 5 5 27 100 Pen #5 - 5112-614 5 3 24 60 Pen #6 5/12-6/7 5 5 27 100 average 5/12-6/4 90.0 Pen #1 6/4-7/5 3* 2 32 67 55 40 Pen #2 6/4-7/5 5 5 32 100 55 100 Pen #3 615-7/5 5 5 31 100 55 100 Pen #4 6/8-7/6 5 4 29 80 56 80 Pen #5 615-7/6 3 3 32 100 56 60 Pen #6 6/8-7/6 5 3 29 60 56 60 average 6/5-716 84.5 cumulative average 5/12-7/6 80.0 Pen #1 716-8/2 2 2 28 100 83 40 Pen #2 7/6-8/2 5 4 28 80 83 80 Pen #3 716-8/2 5 4 28 80 83 80 Pen #4 7/7-83 4 4 28 100 84 80 Pen #5 7/7-8/3 3 3 28 100 - 84 60 Pen #6 717-8/3 3 2 28 67 84 40 average 717-813 87.8 cumulative average 5/124/3 68.0 Pen#l 8/3-8/31 2 2 29 100 112 40 Pen #2 813-8/31 4 4 29 100 112 80 Pen #3 8/3-9/1 4 4 30 100 113 80 Pen #4 8/4-9/1 4 4 29 100 113 80 Pen #5 814-912 3 2 30 67 114 40 Pen #6 814-9/1 2 2 29 100 113 40 average 8/4-9/1 94.5 cumulative average 5/12-9/1 64.0

• I fish lost while measuring I-- r_- r=_- A-7r~n r=l r--1 fr= r.=- r-. I CZJ i 1,1--

43 Table 14. Gut contents expressed as percent volume (the volume of each species expressed as a percentage of the total volume of food from all stomachs) for hatchery and wild fish averaged over 6/4-8/13, 2002, Plymouth Harbor.

Tagged Wild (n=15) (n=20)

Arthropod 34.0% 57.5% Total Arthropod Crustacean Decapod Brachyura decapod juvenile General 6.7% 2.5%

Paguridae juvenile 2.1% 3.5%

lsopoda 2.3% 5.4%

Copepod General 1.4% 2.6%

Calanoid 0.1% 38.1%

Unidentified 0.0% 4.9%

Insect larvae 21.2% 0.5%

Annelida 24.1% 23.0% Total Annelida Polychaete Spionidae 3.5% 5.0%

Orbinfidae 0.0% 4.5%

Unidentified 20.6% 13.6%

Mollusca Bivalve 3.5% 2.1% Total Mollusca Cnidaria Polypoid larvae 3.5% 6.5% Total Cnidarla Others 34.8% 10.8% Total Others Sand 3.7% 0.5%

Rock 0.0% 4.8%

Animal remains 16.9% 5.5%

Terrestrial seeds 14.2% 0.0%

Total 100% 100%

44 L Table 15. Gut contents from seine samples 2002 Hatchery Average % volume of gut contents Date 6/4/2002 n

7 Arthopoda Annelid 83.9% 16.1%

Cnidaria 0.0%

Mollusca 0.0%

Other 0.0%

L 6/13/2002 2 1.0% 0.0% 0.0% 25.0% 74.0%

6/18/2002 7/2/2002 1

2 60.0%

41.0%

40.0%

9.5%

0.0%

0.0%

0.0%

0.0%

0.0%

49.5%

L 7/30/2002 2 7.5% 66.5% 0.0% 0.0% 26.0%

8/13/2002 1 0.0% 50.0% 50.0% 0.0% 0.0%

15 Wild Date n Arthopoda Annelida Cnidaria Mollusca Other, L 6/4/2002 3 38.7% 38.0% 0.0% 0.0% 23.3%

6/13/2002 6/18/2002 7/2/2002 2

4 4

75.0%

90.0%

99.5%

25.0%

5.3%

0.0%

0.0%

0.0%

0.0%

0.0%

2.8%

0.0%

0.0%

2.0%

0.5%

LI 7/30/2002 3 10.0% 63.3% 3.3% 10.0% 13.3%

8/13/2002 4 25.3% 21.3% 29.8% 0.0% 23.8%

20 L

L L

L7 L

L

45 Table 16. Gut contents from seine samples 2003 Hatchery  % volume of gut contents Date n Arthopoda Annelida Mollusca Other 5/28/2003 5 0.6 99.4 0.0 0.0 6/4/2003 3 2.0 98.0 0.0 0.0 6/6/2003 5 30.0 70.0 0.0 0.0 6/12/2003 5 0.0 100.0 0.0 0.0 6/17/2003 7 11.4 87.1 0.0 1.4 7/3/2003 5 32.6 49.4 0.0 18.0 7/24/2003 5 33.7 66.0 0.0 0.3 9/16/2003 1 0.0 0.0 99.0 1.0 L 9/30/2003 1 95.0 5.0 0.0 0.0 37 Wild Date n Arthopoda Annefida Mollusca Other 5/28/2003 0 0 0 0 0 6/4/2003 0 0 0 0 0 L 6/6/2003 0 0 0 0 0 6/12/2003 0 0 0 0 0 6/17/2003 7 0.1 85.4 0 14.3 7/3/2003 5 38.8 40 0.2 21.4 7/24/2003 4 2.8 72.3 0 25 9/16/2003 5 30 10 10 50 L 9/30/2003 5 20 22 20 38 26 i, Caged Hatchery date n arthopoda annelida mollusca other 8/13/2003 5 39 58.5 0.5 2 hi 9/30/2003 4 4 44 7 45

46 L Table 17. Gut contents expressed as percent volume (the volume of each species expressed as a percentage of the total volume of food from all stomachs) for hatchery and wild fish averaged over 6/17-9/30, 2003, L

Plymouth Harbor. H W Hatchery Wild  : LJ n=17 n=26-Arthropod Crustacean 25.8% 17.6% Total Arthopod Decapod 1.5% 0.0%

Brachyura decapod juvenile 0.0% 0.0%

Paguridae juvenile 0.0% 3.8%

Caridea decapod 0.0% - 3.8%

Isopoda 0.6% 0.0% L Copepoda Harpactacoid 0.1% 2.1%

Amphipod Ampeliscidae 2.9% 3.5%

L Gammaridae 1.2% 0.4%

Lysianassidae 4.7% 0.0% -

Corophiurn 6.2% 2.5%

Unidentified Insect larvae 5.6%

2.9%

1.3%

0.1% L Annelida 62A% 47.8% Total Annelida Polychaete Spionidae 1.8% 9.2%

L Polydora ligni 9.9% 0.4%

Cirratulidae 1.2% 0.0% L Maldanidae 4.0% 4.8%

Nereidae 0.6% 0.4%

Phyllodocidae Unidentified 7.1%

37.9%

1.0%

32.1%

CL Mollusca Bivalve 5.8%

5.8%

5.8%

3.8%

Total Moliusca L Mya arenaria 0.0% 1.9% L Others 6.0% 28.8% Total Others Animal remains 5.6% 28.3% L Total 100% 100%

The volume of each species is expressed as a percentage of the total volume of food from all stomachs U

- L L

L

47 Table 18. Gut contents from seine samples 2004 I iatchery YU Y  % volume of gut contents date n arthopoda annelida mollusca other 5/11/2004 12 60.0 10.0 0.0 30.0 5/19/2004 5 0.2 99.0 0.0 0.8 5/24/2004 10 2.7 97.3 0.0 0.0 6/3/2004 11 0.1 99.9 0.0 0.0 6/18/2004 10 8.7 61.4 0.0 29.9 7/2/2004 5 0.8 74.3 0.0 25.0 9/1/2004 5 0.0 5.0 0.0 95.0 9/16/2004 2 0.0 45.0 0.0 55.0 60 Wild YOY date n arthopo da annelida mollusca other 5/10/2004 0 5/11/2004 0 5/19/2004 0 5/24/2004 0 6/3/2004 0 6/18/2004 12 96.9 2.1 0.0 1.0 7/2/2004 5 34.0 48.0 0.4 17.6 9/1/2004 5 0.0 20.0 0.0 80.0 9/16/2004 2 2.5 38.0 0.0 59.5 24 Wild Age 1+

date n arthopoda annelida mollusca other 5/10/2004 2 5.0 0.0 0.0 95.0 5/11/2004 5 8.6 91.4 0.0 0.0 5/19/2004 5 6.6 93.4 0.0 0.0 5/24/2004 10 12.1 78.3 0.0 9.6 6/3/2004 12 0.5 98.7 0.8 0.0 34 Caged Hatchery date n arthopoda annelida mollusca other 9/30/2004 6 1.8 60.2 1.3 36.7

48 Table 19. Gut contents expressed as percent volume (the volume of each species expressed as a percentage of the total volume of food from all stomachs) for hatchery and wild fish averaged over 5/10-9/16, 2004, Plymouth Harbor.

Hatchery Wild n60 n-58 L Arthropod 12.6% 25.0% Total Arthopod Crustacean Decapod L

Brachyura decapodjuvenile 0.0% 0.0%

Paguridae juvenile 0.0% 0.0%

Caridea decapod L

Crangonseptemspinosa 0.0°/O 0.1%

Isopoda 0.0% '0.5% V Copepoda L

Calanoid 12.4% 23.2%

Ostracod Amphipod 0.0% 0.1%

L Ampeliscidae 0.1% 0.6%

Gammaridae 0.0% 0.1%

Lysianassidae 0.0% 0.0% .

Corophium 0.0% 0.1%

Unidentified 0.0% 0.0%

Insect larvae Chironomidae 0.0% 0.4%

Annelida 64.8% 59.8% Total Annelida Polychaete Spionidae 6.8% 12.1%

Polydoraligni 39.2% 31.9%

Cirratulidae 0.0% 0.5%

Orbiniidae 0.0% 0.0%

Maldanidae Nereidae 3.8%

0.1%

5.1%

0.0%

1.1%

L Phyllodocidae 1.1%

Unidentified 13.9% 9.0% r Mollusca 0.0% 0.2% Total Mollusca Bivalve Mytilus sp. 0.00/% 0.2% L Mya arenaria 0.0% 0.0%

Others 22.6% 15.0% Total Others L Artemia sp. nauplii and eggs 1.8% 0.0%

Animal remains 15.1% 8.1%

Barnacle cirri 1.8% 1.5% L Fecal pellet 1.8% 0.0%

4.2%

Hydrozoa Sand 1.8%

0.4% 1.1% L Total 100% 100% L

_ a--

- W- ft I- r- - --- c-E C-- - r- - r r_ - Ir. Z a _- E.

49 Table 20. Pen experiment details - 2003 Hatchery YOY Wild YOY Hatchery Wild winter flounder winter flounder YOY YOY Experiment Date Start Finish Start Finish Crabs Other fish survival survival LT#I 5/20-6/17 10 5 50%

6/17-7/15 5 4 1 2 80%

7/15-8/13 4 4 100%

LT #2 6/19-7/14 5 2 2* I 2 40%

7/14-8/13 2 2 2 2 100% 100%

LT#3 6/19-7/15 5 4 3 1 80%

7/15-8/13 4 3 I 75%

LT#4 6/19-7/14 5 3 2* 60%

7/14-8/12 3 2 2 4 67% 100%

LT#5 6/17-7/16 5 4** 1* 80%

7/16-8/12 4 4 1 I*** 100% 0%

LT#6 6/19-7/16 5 2 2 4 2 40%

7/16-8/12 2 2 2 2 100% 100%

LT#7 8/13-9/30 5 4 2 1 80%

LT#8 8/13-9/30 5 3 5 7 12 60%

• wild YOY not found during pen setup

• • I fish lost while measuring

• • • Wild fish recovered smaller than wild fish introduced

50 L Table 21. Growth rates of caged and uncaged hatchery fish in 2003.

Experiment 1

uncaged date 5/20-6117 5/15-6/17 slope 0.13 0.76 RW 0.97 p-value

<0.001 L

hatchery fish 1 6/17-8/13 0.38 0.99 0.06 Average 6/17-8/13 0.43 2 6/17-8/13 0.52 0.99 0.04 n 6 3 6/17-8/13 0.31 0.90 0.20 st err 0.03 4 6/17-8/13 0.47 0.98 0.01 5 6/17-8/13 0.39 0.99 0.01 6

uncaged 6/174/13 6/17-8/6 0.49 0.74 0.99 0.92 0.01

<0.001 L

hatchery fish 7 8/13-9/30 0.13 Average 8/13-9130 0.13 8 8/13-9/30 0.13 uncaged 8/13-9/30 0.19 0.88 0.06 hatchery fish The p-value represents the probability that the slope is significant different from zero.

L L

L L

L i

I

51 Table 22. Growth rates of caged and uncaged hatchery fish in 2004.

Experiment date slope R;! D-value I Pen 1 5/12-7/5 0.61 0.99 0.05 Pen 2 5/12-7/5 0.37 0.99 0.05 Average 5/12-7/5 0.44 Pen 3 5/12-7/5 0.41 0.98 0.09 n 6 Pen 4 5/12-7/5 0.38 0.98 0.1 st err 0.04 Pen 5 5/12-7/5 0.43 0.99 0.02 Pen 6 5/12-7/5 0.41 0.99 0.03 uncaged 5/12-7/5 0.64 0.97 <0.001 Pen 1 7/5-8/31 0.18 0.99 0.02 Pen 2 7/5-8/31 0.1 0.68 0.38 Pen 3 7/5-8/31 0.08 0.99 0.01 Average 7/5-8/31 0.14 Pen 4 7/5-8/31 0.26 0.93 0.02 Pen 5 7/5-8/31 0.01 - 0.59 0.48 Pen 6 7/5-8131 0.23 0.98 0.09 uncaged 7/5-8/31 0.46 0.99 0.19 The p-value represents the probability that the slope is significant different from zero.

52 Table 23. Pen experiment conditions - 2004 Hatchery YOY Hatchery winter flounder Wild YOY YOY Experiment Date Start Finish Anoxic winter flounder Crabs survival Pen 1 5/12-6/3 5 4 80%

6/3-7/5 3* 2 X I 67%

7/5-8/2 2 2 X 100%

8/2-8/31 2 2 slightly 100%

8/31-9/30 2 0 X 0%

Pen 2 5/12-6/3 5 5 100%

6/3-7/5 5 5 2 100%

7/5-8/2 5 4 X 2 80%

8/2-8/31 4 4 100%

8/31-9/30 4 4 1 100%

Pen 3 5/12-6/4 5 5 100%

6/4-7/5 5 5 I I I . 100%

7/5-8/2 5 4 slightly 80 8/2-9/1 4 4 slightly 2 100%

9/1-9/30 4 lost 0%

Pen 4 5/12-6/7 5 5 100%

6/7-7/6 5 4 2 80%

7/6-8/3 4 4 slightly 1 100%

8/3-9/1 4 4 X 100%

9/1-9/30 4 2 50%

Pen 5 5/12-6/4 5 3 60%

6/4-7/6 3 3 2 1000%

7/6-8/3 3 3 100/0 8/3-9/2 3 2 :67%

9/2-9/30 2 lost .0%.

Pen 6 5/12-6/7 5 5 100%

6/7-7/6 5 3 3 60%

7/6-8/3 3 2 67%

8/3-9/1 2 2 slightly 100%

9/1-9/29 2 lost 0%

• I tag lost while measuring The X denotes the presence of anoxic conditions All wild YOY winter flounder were smaller than the hatchery-reared YOY flounder.

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MARINE ECOLOGY STUDIES Related to Operation of Pilgrim Station Section 3.5 Larval Transport Study ANNUAL REPORT No. 65 JANUARY 2004 THROUGH DECEMBER 2004 Environmental Protection Group Entergy Nuclear-Pilgrim Station

Entergy Nuclear Generation Company Plymouth, MA Study of Winter Flounder Larval Transport in Coastal Cape Cod Bay and Entrainment at Pilgrim Nuclear Power Station Spring 2004 ENSR Corporation Marine Research, Inc.

February 2005 Document Number 10658-001

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CONTENTS 4 n IKIT'rDfl 1.u Al's I f f.%

ItrTflMI 90' ................................................................. 1-1 i'

2.0 FIELD SAMPLING PROGRAM .................................... 2-1 2.1 Sampling Program Design ................................... 2-1 2.2 Winter Flounder Larvae Sampling ................................... 2-1 2.3 Hydrodynamic Measurements ................................... 2-3 2.4 Water Column Monitoring ................................  ; 2-4 3.0 STUDY RESULTS .................................... 3-1 3.1 Winter Flounder Larvae Sampling Results ................................ 3-1 3.2 Hydrodynamic Monitoring Results .... . 4..................

3.3 Water Column Monitoring Results ................................ 3-6 4.0 DATA ANALYSIS AND ASSESSMENT .................................... 4-1 4.1 Volumetric Water Flowrate Analysis ................................... 4-1 4.2 Net Larval Transport and Entrainment Analysis ...................................4-3 4.3 Entrainment Analysis by Tidal Flushing ................................... 4-5

5.0 CONCLUSION

S ....................................... 6-1 L

6.0 REFERENCES

................... 6 L 6

L i February, 2005 PigrmO4%reporLNrvTransRepourO(W.doc

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M77MIP LIST OF TABLES Table 2-1 Long-Temi Hydrodynamic Survey Deployment Description ................................................. 2-5 Table 3-1 Larval Density and Proportion By Depth Strata .................................................................... 3-3.

Table 3-2 Larval Stage Percentages of Total At Each Station Summarized For Each Survey ........... 3-3 Table 4-1 Analysis of Net Volumetric Flowrate in Bay Study Area Compared to PNPS Wthdrawal ...4-3 Table 4-2 Larval Flux and Entrainment Results Transect A-D ............................................................ 4-4 Table 4-3 Larval Flux and Entrainment Results by Tidal Flushing ....................................................... 4-5 JAlWateriPmjecFiLes~P1OOktOB58a~_R11OB58Q1- ii February, 2005 PilgiimOeport~arvTransReportO4f.doc

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LIST OF FIGURES Figure 2-1 Locations of Larvae Sampling and ADCP Deployment Stations ........................................ 2-2 Figure 3-1 Total Larval Densities For Sampling Survey I .................... ............................... -1 Figure 3-2 Total Larval Densities For Sampling Survey 2................................................... 3-2 Figure 3-3 Velocity Normal to Transect A-D: Flood Tide June 17, 2004 ......................................... ...... 3-5 Figure 3-4 Velocity Normal to Transect A-D: Ebb Tide June 17, 2004 ................................................. 3-5 Figure 3-5 Velocity Normal to Transect B-C: Flood Tide June 17, 2004 .............................................. ;3-6 Figure 3-6 Velocity Normal to Transect B-C: Ebb Tide June 17, 2004 ................................................ 3 Figure 4-1 Water Velocities During Sampling Survey 1................................................. 4-2 Figure 4-2 Water Velocities During Sampling Survey 2........................................................................4-2 Figure 4-3 Tidal Flushing Analysis Areas .................................................. 4-6 J:\Wat\PrcjectFiLes\P1OO\1065_MRI\1065S001- i iii February, 2005 PilgrbimO4\report~larTransReportOW.doc

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1.0 INTRODUCTION

Winter flounder (Pseudopleuronectesamercanus)are commercially important inCape Cod Bay and are a dominant species collected by the entrainment monitoring program at Pilgrim Nuclear Power Station (PNPS). The objective of this study was to evaluate the impact of winter flounder larvae entrainment at PNPS through direct field measurements. An approach was applied whereby field measurements were collected to determine the relative amount of net volumetric flow and winter flounder larvae entrained into the PNPS cooling water system compared to the net volumetric flow and amount of winter flounder larvae passing PNPS in offshore Cape Cod Bay waters.

This program was designed to update the similar studies completed in2000 (ENSR and MRI, 2000) and 2002 (ENSR and MRI, 2003), based on the suggestions and comments of federal and state agency reviewers. The results of this study confirmed those of the prior studies inthat:

• PNPS withdraws a relatively small percentage of the available net volumetric flow of water-generally less than 0.1%.

• The number of winter flounder larvae entrained by PNPS is a relatively small percentage of the net larval transport-conservatively estimated at less than one percent.

The field program was designed to collect sufficient measurements to determine the flux of winter flounder larvae moving along the Plymouth coast and the flux of winter flounder entering PNPS. To determine larvae flux, larvae concentration and volumetric flowrate of water were required. The field program featured determination of larval densities and water velocity measurements along the Plymouth coast inCape Cod Bay and determination of larval densities inthe PNPS cooling water system.

The field program was conducted between late May and late June and consisted of the following elements:

• Winter flounder larvae sampling -

o in Cape Cod Bay at five offshore stations, and o inthe PNPS discharge canal (entrained inthe cooling water flow).

• Water velocity measurements -

o at four offshore stations in Cape Cod Bay, using bottom-mounted Acoustic Doppler Current Profiler (ADCP) units, and o along transects using boat-based ADCPs.

Larvae and water velocity measurements were collected concurrently inlate May and early June 2004 to support determination of larval flux. Larvae sampling was conducted along the Plymouth coast and at

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PNPS during two surveys, between May 26 and June 4, 2004. For each survey, larval samples were obtained four times, twice during the day, and twice during the night, during a one-day period. Water velocity measurements were collected continuously from fixed stations between May 20 to June 20,2004 U and from boat-based transects on June 17, 2004.

The ichthyoplankton data were combined with the current measurements to determine the flux of larvae L

along the coast of Cape Cod Bay, for each of the two daily surveys. These values were then compared to the number of larvae entrained by the PNPS cooling system, as determined from the entrainment study, during the same two daily measurement periods.

Section 2 of this report describes the field sampling program. Section 3 provides the field study results. L Section 4 provides an analysis of the study results. Section 5 provides the study conclusion and an overall assessment of the entrainment by PNPS on winter flounder larvae from Cape Cod Bay.

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2.0 FIELD SAMPLING PROGRAM 2.1 Sampling Program Design The field program was designed in part based on the results of the similar studies performed in 2000 and 2002. In particular.

• The sampling stations were deployed in a pattern that would provide the ability to capture currents flowing in any direction, as variable currents were observed during the 2002 study, as well as to perform an alternative analysis of tidal flushing (see Section 4.3).

• Two larvae sampling surveys were performed, as this was deemed sufficient to capture the changes in larval densities observed as the season progressed.

2.2 Winter Flounder Larvae Sampling 2.2.1 Cape Cod Bay Larval winter flounder were collected at five stations in Cape Cod Bay (Figure 2-1). The stations were established in a diamond-shaped patter. Three of the five stations (A,E, and D)were established along a single transect extending from just south of Rocky Point northeast into the 120' depth contour of Cape Cod Bay. The total transect length was approximately five nautical miles. Stations B and C were located approximately one nautical mile northwest and southeast, respectively, of Station E.The close proximity of the larvae sampling stations to the hydrodynamic measurements facilitated correlation of the acquired hydrodynamic data with biological sample data to formulate an estimate of the population of winter flounder contained in Cape Cod Bay coastal waters flowing towards and past PNPS.

The five sampling stations were identified as Stations A through E. The approximate low-water depth at each station was as follows: Station A: 25'; Station B: 98'; Station C: 70'; Station D: 123'; Station E: 90'. As shown on Figure 2-1, the stations were positioned such that station Ewas centrally located between the other stations.

Two field surveys were completed during the spring of 2004: May 26 - 27, and June 3 - 4. Each survey was structured to capture the ebb and flood tides of two tidal cycles on each sampling day (4 sampling events per survey, 2 predominately during the day and 2 predominately during the night). Sampling was conducted at each station using 60-cm diameter ubongo" nets rigged with 0.202-mm and 0.333-mm nylon mesh plankton nets and with an epibenthic bottom sled rigged with a 0.333-mm nylon mesh net. The sled was constructed of PVC pipe identical to the one used for ichthyoplankton sampling near PNPS in 2002 (ENSR and MRI 2003). Tow duration for each sample was approximately six to eight minutes, which provided sample volumes ranging from 85 to 150 cubic meters and an overall average of 120 cubic meters.

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M701-M-Mm the entrainment section 3.3 of this document). Only the 0.202-mm mesh samples were analyzed; the 0.333-mm mesh samples were archived. Due to the abundance of zooplankton, 50% of the samples were split in half using a plankton splitter patterned after Motoda 1959 (see also Van Guelpin et al. 1982).

Counts were converted to larvae per 100 cubic meters of water (density) based on the flow-meter readings.

2.2.2 PNPS Discharge In conjunction with each offshore sampling series, ichthyoplankton samples were also taken from the PNPS cooling water discharge to assess the entrainment of winter flounder larvae. Sampling was conducted near the center of the discharge canal, approximately 30 meters downstream from the headwall, which is the same location used for the routine entrainment monitoring. Samples were collected using a 60-cm diameter plankton net constructed of 0.202-mm nylon mesh. On each survey, samples were scheduled to be taken every three hours for a total of eight samples per 24-hour sampling event. A backwash performed at the Station during the night of June 4 resulted in the collection of seven samples instead of eight. Each collection was made by streaming the net for 10 minutes. Exact filtration volumes were determined using a General Oceanics 2030R2 flowmeter mounted in the mouth of the net.

After sample collection, the net was rinsed from the outside using seawater to wash all plankton into the cod end of the net. The sample was then transferred into a 1-liter, wide mouth bottle and preserved using sufficient buffered Formalin to obtain a 10% solution. A waterproof tag listing the station, date, time of collection, and the flow-meter readings was placed into each sample container. Samples were returned to the laboratory and processed as described above for the offshore samples.

2.3 Hydrodynamic Measurements The hydrodynamic measurement component of the field program was designed to support determination of the total volumetric flowrate of water along the Plymouth coast. The long-term, fixed-base hydrodynamic monitoring program was scheduled to include the time of the two winter flounder larvae sampling surveys.

The hydrodynamic field program consisted of two components, a long-term survey and a synoptic survey.

The long-term and synoptic surveys successfully collected the data required to support the study and are described below.

2.3.1 Long-term Hydrodynamic Survey Hydrodynamic measurements were continuously collected at four locations (A, B, C, and D see Figure 2-1). At each hydrodynamic sampling location, the following measurements were collected for a period of one month.

-- ------- ---- --- 2-3 February, 2005 RilgrtmO4XreportNLarvTransReportO4f .doc

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• Water velocity measurements were recorded throughout the water column using a bottom-based acoustic Doppler current profiler (ADCP). The ADCP measures the magnitude and direction of water movement through transmission of acoustic signals and interpretation of L

Doppler frequency shifts in acoustic retums. ADCP measurements were acquired at one-meter intervals throughout the full depth of the water column.

• Sea surface elevation using a tide gauge (pressure transducer).

A description of long-term survey deployments, equipment, and data collection is provided in Table 2-1 for each location. U The long-term hydrodynamic survey achieved the 100% data collection goal. Processing, analysis and application of the long-term hydrodynamic measurement data is described in Section 3.

2.3.2 Synoptic Hydrodynamic Survey Synoptic, boat-based water velocity measurements were collected using an ADCP instrument on 17 June 2004. The boat-based ADCP survey featured measurement of water velocities (direction and magnitude) at one-meter intervals throughout the water column. Two transits of Transect A-D and Transect B-C were performed, once each during an ebb and flood tide. The ADCP unit was rigidly mounted in a frame suspended over the side of the survey vessel. Published tidal information for this date at Gumet Point L

indicated low tide at 06:00, high tide at 12:11 and low tide at 18:02.The synoptic survey transits were performed at the times indicated below: L

• Flood tide: Transect B-C 08:55 to 09:41 and Transect A-D 10:03 to 11:18

• Ebb tide: Transect A-D 14:04 to 15:19 and Transect B-C 15:42 to 16:20 The synoptic survey achieved the 100% data collection goal. Processing, analysis and application of synoptic hydrodynamic measurement data is described in Section 3. L 2.4 Water Column Monitoring Measurements of water temperature (+/- 0.10 C), salinity (+/- 0.1 oloo), and dissolved oxygen ( 0.1 ppm) l were recorded at each station immediately preceding the surface ichthyoplankton tow using a Hydrolab Quanta multiparameterwaterquality instrument. Readings were recorded at surface, mid-depth and at a depth of within one meter of the bottom (Station A) or up to a maximum depth of 23 meters, the length of L

cable available. Bottom temperatures were also recorded by both the tide gauges and ADCPs. The water quality instrument failed during the first survey after the first samples were collected at Stations A and B, i for 10% data capture during the first survey. All water quality observations were successfully made for the second survey. U J:\WaterPrjectFikesP1010658jMRI1 0658001-PephO4 aNvTransReporto4fdoc February, 2005 L

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Table 2-1 Long-Tenn Hydrodynamic Survey Deployment Description Station:A >-Staton B-- StationG`-.'I Station D i, 410 56' 56.50" N 410 58' 42.19" N 410 56' 24.00" N 410 58' 27.94" N i 700 34' 15.20" W 70°32' 45.40" W 700 31' 11.40" W 70°28' 11.13" W instrument-C g o 27 feet 104 feet 88 feet 132 feet I tl.

t 5119/2004 at 13:10 5119/2004 at 12:19 5/19/2004 at 12:45 5/19/2004 at 11:24 R e 6/22/2004 at 09:00 6/17/2004 at 12:23 6/17/2004 at 13:07 6/17/2004 at 11:40 34 days, 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> 30 days 30 days 30 days D 34 days, 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> 30 days 30 days 30 days X iduratz n

- RD Instruments, RD Instruments, RD Instruments, RD Instruments, Wi ,Workhorse Sentinel Workhorse Sentinel Workhorse Sentinel Workhorse Sentinel meA < ADCP, 1200kHz ADCP, 600kHz ADCP, 600kHz ADCP, 600kHz frequency (serial frequency (serial frequency (serial frequency (serial

1. 0256) #2355) #1302) #1301) e Recorded every 15 Recorded every 15 Recorded every 15 Recorded every 15

.8. eolt~ati minutes throughout minutes throughout minutes throughout minutes throughout t the water column the water column the water column the water column y Coastal Macrowave Coastal Macrowave Coastal Macrowave Coastal Macrowave Non-directional Non-directional Non-directional Non-directional Wave Gauge Wave Gauge Wave Gauge Wave Gauge (seria #10215) (serial #10377) (serial #10301) (serial #10222)

Water level Water level Water level Water level gaug measurements measurements measurements measurements o recorded every 15 recorded every 15 recorded every 15 recorded every 15 t minutes minutes minutes minutes A--}v- -,- , Xk e s<:.

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L 3.0 STUDY RESULTS I

3.1 Winter Flounder Larvae Sampling Results Densities of larval flounder per 100 m3 of water by developmental stage for each sample appear in U

Appendix A. Larval flounder were present on each sampling occasion (Figure 3-1 and Figure 3-2).

I Survey I L

L L

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26-May11:30 26-May17:30 26-May23:30 27-May05:30 27-May11:30 Figure 3-1 Total Larval Densities For Sampling Survey I l

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50 00 03-Jun 00:00 03-Jun 06:'00 03-Jun 12:00 Figure 3-2 Total Larval Densities For Sampling Survey 2 3.1.1 Cape Cod Bay The distribution of winter flounder larvae among developmental stage is shown in Table 3-1 pooled over both collection dates within sampling strata and including the PNPS discharge. All four developmental stages were found in the collections although stage 2 and 3 larvae accounted for 80 to 90% of the total within each strata. The low contribution of early stage 1 larvae likely reflected, at least in part, the late May, early June sampling dates, relatively late in the spawning season. The low numbers of stage 4 larvae probably reflected their lower numbers in general as a result of natural mortality and gear avoidance as a result of their benthic life style.

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ENR. U k-RkZAROWC rM77TIMMMr~yr Table 3-1 Larval Density and Proportion By Depth Strata L

- ,. UppStrata., Lower Strata Bottom Str PNPS Discharge..

I Stage Denisity..%~ofTotal ~'Density ~~%of!Total .,Density %o~4'fTotal~~ [ensity" of Total" It 2

7.4 31.2 14.8%

61.9%

9.3 44.7 11.5%

55.0%

8.4 183.0 2.0%

43.3%

1.9 33.4 1.2%

20.9% L 7 11.7 23.2% 27.1 33.4% 231.3 54.7% 123.7 77.2%

Totat 0.1 50.4 0.2% 0.1 81.2 0.1% 0.4 423.1 0.1% 1.2 160.2 0.8%

U Overall, larval densities in Cape Cod Bay averaged higher near bottom. Densities in the upper half of the U

water column collected with the bongo net averaged 50.4 per 100 m3 of water compared with 81.2 per 100 m3 in the lower portion and 423.1 per 100 m3 near bottom as determined with the sled. Densities averaged 160.2 per 100 m3 in the PNPS discharge.

L Summarized across stations and events for each survey, the percentages of each larval stage observed L are given in Table 3-2. In general, larval densities in Cape Cod Bay were higher near shore and lower farther off shore and in deeper water, and larval densities in the PNPS discharge were within the range observed in the Bay. During the first survey, stage 2 larvae were most abundant in Cape Cod Bay, except L

at Station A, where like the PNPS discharge, stage 3 larvae were most abundant. Inthe second survey, stage 2 and 3 larval densities in Cape Cod Bay were found in about equal proportion, except at Station D, where stage 2 was most abundant and stage 1was still significant. Stage 3 was fully three-quarters of the larvae observed in the PNPS discharge during the second survey.

Table 3-2 Larval Stage Percentages of Total At Each Station Summarized For Each Survey L

.. e

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AE

~rveyi s E PNPS ISCD A 'B

- ure CD X

E X

PNPS

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_ 3 9 11 16 20 1 1 2 6 16 4 1 i  ;%' 42 63 62 66 60 19 41 43 49 60 53 23 54 28 27 18 20 79 58 55 45 25 43 75 4 _ 0.1 0 0 0 0 1.3 0.2 0 0.2 0.5 0 0.3 Totai Denslty 431 133 123 31! 114 151 514 123 701 16 108 172 L 3.1.2 PNPS Discharge L Mean densities of flounder larvae observed in the PNPS discharge were 149.8 and 172.0 per 100 m3 of water for the May 26 and June 3 series, respectively.

The percentages of larval stages observed in the PNPS discharge are summarized above in Table 3-2.

Stage 3 larvae were observed at a much higher percentage compared to the three other stages. Stage I L

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.,..,, ,........r larvae were approximately one percent of the total observed, suggesting that the spawning season ended earlier in May. Stage 4 larvae made up one percent or less of the total in both surveys.

3.2 Hydrodynamic Monitoring Results 3.2.1 Long-term Hydrodynamic Survey Hydrodynamic data from each of the three locations were inspected, processed, and exported for further analyses using RD Instruments WnADCP software. The conversion of the water velocity vectors (magnitude and direction) to velocity normal to a transect results in velocities and water flowrates being reported such that positive values are flowing North and/or West, and negative values are flowing South and/or East.

Over the duration of the ADCP deployment, the observed extremes of velocity averaged over the entire water column were, in meters per second:

IStation North POPt st A 0.185 -0.352 0.145 -0.406 B 0.188 -0.282 0.118 -0.172 C 0.320 -0.356 0.140 -0.196 D 0.234 -0.302 0.121 -0.157 Hydrodynamic data are provided in electronic form as Appendix C.

3.2.2 Synoptic Hydrodynamic Surveys Data from the four boat-based ADCP tows were inspected using RD Instruments WinRiver software, and exported for further analysis. The ADCP transect tows of June 17, 2004 are presented in Figure 3-3 to Figure 3-6. These figures show the velocity normalized perpendicular to the A-D and B-C transects, with positive values flowing northwest, and negative values flowing southeast. The results of the synoptic surveys show that the current profiles vary across the transect, however, the placement of the fixed ADCP stations should capture the major flow regimes. The synoptic survey also shows that the variation in currents is predominantly with depth rather than distance along the transect. As expected flow is mostly to the South (negative velocities across the transect in Figure 3-3) during flood tide and mostly to the North (positive velocities across the transect in Figure 3-4) during ebb tide.

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WPn7-rf.rff?-rM-341W Projected Velocity [ms] (Ref: Btm

• 4_ 4a'%

L 8 1078 2148 3219 4289 Length [n]

. . 5360 6430 : 7500 0571 U I Figure 3-3 Velocity Normal to Transect A-D: Flood Tide June 17,2004 3410 ProJected Velocity Ws] (Ref: BMM) 4s - aid J

~ ggr e ~i' , , C 31 1105 2179 3253 4327 5402 6476 7550 8624

. Length [m] -

Figure 3-4 Velocity Normal to Transect A-D: Ebb ide June 17, 2004 LI L

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study was intemperature values. Bottom water temperature obtained from the ADCP instruments for the May survey ranged from 4.2° C at Station B to 10.60 C at Station A. Based on average readings for each station on the June survey, surface water temperatures ranged from 11.30 C at Station B to 15.0 .C at U Station A. Bottom readings ranged from 4.00 C at Station B to 11.40 C at Station A. Along the sampling transect both surface and bottom water averaged higher at inshore Station A than further offshore, the.

difference between locations being more pronounced in bottom water due to the increasing depth along L

the transect. Averaging all bottom temperatures for each survey, the May survey (6.20 C)was coolerthan the June survey (6.80 C). L L

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4.0 DATA ANALYSIS AND ASSESSMENT The data discussed above were analyzed for (1)the percentage of net volumetric flow in nearby coastal Cape Cod Bay waters withdrawn by PNPS and (2) the percentage of winter flounder larvae in the net coastal flow entrained by PNPS. This allows an evaluation of the overall effect of winter flounder larvae entrainment at PNPS.

A separate calculation of the percentage of coastal flow withdrawn and larvae entrained by PNPS was performed for each of the two sampling surveys conducted. In addition, the volumetric flow analysis was performed over the entire monthly period that the hydrodynamic measurements were conducted. The larval analysis was performed for each of the four winter flounder larvae life stages and for total larvae.

Details of the analysis procedures and results are discussed below.

4.1 Volumetric Water Flowrate Analysis Inorder to correlate the four continuous-depth ADCP stations with the five discrete-depth larvae sampling stations, the ADCP water velocity data was processed in the following manner:

• The flow across the transect A-D (from southwest to northeast) was analyzed. At each ADCP station, the water column was divided into three segments based on total depth at the time of the reading: the upper half from half to three meters above the bottom, and the bottom three meters. The component of the ADCP velocity normal to the transect was averaged over each depth segment of the water column, for each 15-minute ensemble of data. Figure 4-1 and Figure 4-2 contain plots of water depth and the average velocities normal to the transect for ADCP stations A and D and for each depth interval during the two larvae sampling surveys.

• For larvae sampling station E, velocities were estimated by taking the average of the transect normal velocities at the adjacent stations ie., E is average of B and C.

• The flowrate of water across the transect was then calculated by multiplying each of the transect velocity series by the estimated cross-sectional area of the transect represented by that value. The cross-sectional areas were determined for each segment by multiplying the appropriate water depth interval at the station for that time by one-half of the combined distance to the two adjacent stations.

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• Inorder to correlate the ADCP time series with the discrete larvae sampling events, the ADCP-based water flowrate data was averaged over the duration of each tidal phase. The tidal phase was defined as the time between the maximum and minimum tide heights at the station.-The sum of the flowrates during the four tidal phases also was the basis for daily estimates of water flowrate across the study transect.

Table 4-1 compares the daily water flowrates during the sampling events with the average daily water flowrate during the study period. The percentage of the volumetric flow withdrawn by PNPS (with both pumps operating at the rated total maximum of 19.56 m3/s)ranges from 0.02% to 0.03% for the two larvae sampling days.

Table 4-1 Analysis of Net Volumetric Flowrate inBay Study Area Compared to PNPS Withdrawal May 26-27 June 34r 72,587 86,141 0.03% 0.02%

4.2 Net Larval Transport and Entrainment Analysis 4.2.1 Larval Transport Analysis The flux or transport of winter flounder larvae flowing along the coast was determined for each of the two surveys using larvae density and hydrodynamic measurements. This approach integrated current velocity, water depth and larval stage density over the cross-sectional area of the transect during the time of each tidal phase.

The calculation was performed for each of the four winter flounder larval stages and the total winter flounder larval density at each of the four 6-hour tidal periods that constituted one 24-hour "day". The net larval flux over a given 8-hour tidal period was determined by multiplying the density of larvae (larvae/m 3) times the flowrate of water (m3Is) to yield larvae/second over the 6-hour period. The water column depth intervals were assigned corresponding larvae samples: surface by net, bottom by net, and sled. As noted in Section 2,the sled larvae sampling was incomplete for the first survey, so the bottom net samples were used for the deepest water column interval when sled data was missing. For each study day, the net larval flux was determined by taking the sum of the net larval flux over all the 6-hour tidal periods.

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L 4.2.2 Larval Entrainment Analysis The number of winter flounder larvae entrained by PNPS during both surveys was determined from the U

station flow rate and the eight larval entrainment samples collected during the day specifically for this study. The calculation was performed for each of the four winter flounder larval stages, by multiplying the I number of larvae for each stage entrained by the station by the station flow rate for the 6-hour tidal cycle over which the ambient flounder samples were collected. The sum of each of the 6-hour periods became U U

the total entrainment per day.

The percentage of each larval stage entrained was determined by dividing the number of larvae entrained during the day by the number of larvae carred past the station in the net longshore current (and then multiplying by 100 to obtain a percentage). The larval entrainment results are presented in Table 4-2. for the major transect in the study area, A-D.

L In general, the results in Table 4-2 indicate that PNPS entrains a very small percentage of the winter flounder larvae in the coastal flow of Cape Cod Bay. These results are similar to those of the larvae transport studies performed in 2000 (ENSR and MRI, 2000) and 2002 (ENSR and MRI, 2003).

L Table 4-2 Larval Flux and EntraInment Results Transect A-D L L

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492,234 547,780,748 182,815,242 705,010 C Er < 0.09 0.39 TV dPNPSi Sta Bay3 e iday 2,106,405 115,972,069 93,189,196 2,270,584 L ti 1.82 2.44 NPOS Larvaei t air E

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Eiad 0.32 0.99 Based on this analysis, it is concluded that the percentage of winter flounder larvae transported in coastal Cape Cod Bay waters that is entrained by PNPS may be conservatively estimated at less than one percent. Though the results in Table 4-2 indicate higher entrainment percentages for Stages 3 and 4 L

larvae, it is likely that the actual entrainment rate for these larval Stages is similar to the total larvae entrainment rate of one percent or less. During Survey 1,the loss of the sled meant that two stations were L J:%WatrProecFilesP100 )10658..MRI%10658001-Pilgrfim4 eport~LazTransReport04t~doc 4-14 February, 2005 U I

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not sampled during two of the four tidal periods, and the rest were not sampled for one of the tidal periods.

Since the sled samples routinely yielded the highest larvae counts, results for Survey 1 likely underestimate larval flux in the Bay. Also, for Stage 4, since the densities are so low, the change incount by one individual has a disproportionately high effect on densities, and thus on the percent entrained. For example, in Survey 1, 18 total Stage 4 individuals were counted inthe PNPS samples, and two total Stage 4 individuals were counted in the net and sled samples in the Bay.

4.3 Entrainment Analysis by Tidal Flushing The spatial arrangement of sampling stations used for the 2004 study enabled an alternative method of calculating larval flux and entrainment. This method was used to determine the total amount of larvae transported by tidal currents into and out of an area defined by one tidal excursion near PNPS, thereby providing a measure of the tidally induced flushing of larvae in the region subject to entrainment by the station. The amount of larvae entrained by PNPS was then compared to this value to obtain an assessment of the entrainment rate compared to larval transport by tidal flushing.

The analysis was performed by the following method:

• Determine total volume of water, entering the study area only (i.e., flowing in a southerly direction), across the B-D transect for each of the three depth segments over the two tide cycle "day-.

• Apportion this total flow volume to each of the five stations according to the area it represents when Thiessen polygons (borders are equidistant from adjacent points) are constructed about the stations, as shown in Figure 4-3.

• Multiply each station's fraction of the total flow by the larval density to get number of larvae flushed from the area during the day.

Results of this analysis are presented in Table 4-3 and generally are one to two orders of magnitude less than the transect method presented in Section 4.2.

Table 4-3 Larval Flux and Entrainment Results by Tidal Flushing

_____ 0 i5s-_ "' Sdrvey1- Isurvey 2 PNPS Larvaelda 31,042 1 37,634 StG Bay LarvaedY 5,370,497,708 81563,085127 UEntraine0.001 0.002 PNPS Larvae/day' 492,234 705,010 Stage 2 Bay LarvaedayM 19,950,035,353 6,724,111,167

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5.0 CONCLUSION

S This was the third larval transport study performed in Cape Cod Bay to examine the key conditions (net water flow and density of winter flounder larvae) affecting the entrainment of winter flounder larvae. These three studies-conducted adjacent to Pilgrim Station in 2000, 2002 and 2004 by ENSR and MRI-were designed to complement each other and were modified as needed, based on the suggestions and comments of federal and state agency reviewers.

They are intended to provide an empirical basis for the conclusion stated in the March 2000 316 Demonstration Report that "there have been no adverse impacts to the integrity of the winter flounder population due to the PNPS thermal discharge or CWIS." (ENSR, 2000)

The results of the 2004 study are similar to those of the previous studies performed in 2000 and 2002.

When viewed together, the significant conclusions are:

• There is a consistent net flow of water and winter flounder larvae to the south along coastal Cape Cod Bay in the vicinity of PNPS.

• A very small amount - less than 0.1% - of the net volumetric flow of water in Cape Cod Bay passes through PNPS.

• The amount of winter flounder larvae in northwest Cape Cod Bay that is entrained by PNPS is conservatively estimated at less than 1% of the net larval transport.

These findings are consistent with the 316 Demonstration Report, which stated that Pilgrim's potential entrainment impact to the winter flounder population is less than 5%. Infact, based on these results, the potential impact to the winter flounder population (less than one percent) is even smaller than the assessment provided inthe 316 Demonstration Report. The clear conclusion is that entrainment at PNPS is minimal, and does not adversely impact the integrity of the winter flounder population.

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6.0 REFERENCES

ENSR and MRI, 2000. Study of Winter Flounder Transport in Coastal Cape Cod Bay and Entrainment at Pilgrim Nuclear Power Station. Prepared for Entergy Nuclear Generation Company.

L ENSR and MRI, 2002. Study of Winter Flounder Larval Transport in Coastal Cape Cod Bay and Entrainment at Pilgrim Nuclear Power Station. Prepared for Entergy Nuclear Generation Company.

L Motoda, S., 1959. Devices of simple plankton apparatus. Memoirs of the Faculty of Fisheries, Hokkaido L University 7: 73-94.

II 6I ii1 Marine Research, Inc., 1986. Winter Flounder early life history studies related to operation of Pilgrim Station-a review 1975-1984. Pilgrim Nuclear Power Station Marine Environmental Monitoring Program Report Series No. 2. 111 pp. + appendix.

L Van Guelpen, L., D.F. Markie, and D.J. Duggan, 1982. An evaluation of accuracy, precision, and speed of several zooplankton subsampling techniques. International Council for the Exploration of the Sea 40: 226-236.

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