ML072200616
| ML072200616 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 03/31/2003 |
| From: | US Dept of Commerce, National Marine Fisheries Service, US Dept of Commerce, National Oceanographic and Atmospheric Administration |
| To: | Office of Nuclear Reactor Regulation |
| Davis J NRR/DLR/REBB, 415-3835 | |
| References | |
| 03-06 | |
| Download: ML072200616 (468) | |
Text
Northeast Fisheries Science Center Reference Document 03-06 36th Northeast Regional Stock Assessment Workshop (36th SAW)
Stock Assessment Review Committee (SARC)
Consensus Summary of Assessments March 2003
Recent Issues in This Series 02-06 Report of the 34th Northeast Regional Stock Assessment Workshop (34th SAW): Stock Assessment Review Commit-tee (SARC) Consensus Summary of Assessments. [By Northeast Regional Stock Assessment Workshop No. 34.] April 2002.
02-07 Report of the 34th Northeast Regional Stock Assessment Workshop (34th SAW): Public Review Workshop. [By Northeast Regional Stock Assessment Workshop No. 34.] April 2002.
02-08 Description of the 2001 Oceanographic Conditions on the Northeast Continental Shelf. By M.H. Taylor, C. Bascunán, and J.P. Manning. May 2002.
02-09 A Compilation of Reported Fish Kills in the Hudson-Raritan Estuary during 1982 through 2001. By R.N. Reid, P.S.
Olsen, and J.B. Mahoney. July 2002.
02-10 Northeast Fisheries Science Center Publications, Reports, and Abstracts for Calendar Year 2001. By L. Garner and J.A. Gibson. August 2002.
02-11 Status of the Northeast U.S. Continental Shelf Ecosystem: A Report of the Northeast Fisheries Science Centers Ecosystem Status Working Group. By J.S. Link and J.K.T. Brodziak, editors, with contributions from (listed alphabeti-cally) J.K.T. Brodziak, D.D. Dow, S.F. Edwards, M.C. Fabrizio, M.J. Fogarty, D. Hart, J.W. Jossi, J. Kane, K.L. Lang, C.M.
Legault, J.S. Link, S.A. MacLean, D.G. Mountain, J. Olson, W.J. Overholtz, D.L. Palka, and T.D. Smith. August 2002.
02-12 Proceedings of the Fifth Meeting of the Transboundary Resources Assessment Committee (TRAC), Woods Hole, Massachusetts, February 5-8, 2002. By R.N. OBoyle and W.J. Overholtz, TRAC co-chairmen. [A report of Transboundary Resources Assessment Committee Meeting No. 5]. September 2002.
02-13 Report of the 35th Northeast Regional Stock Assessment Workshop (35th SAW): Public Review Workshop. [By Northeast Regional Stock Assessment Workshop No. 35.] September 2002.
02-14 Report of the 35th Northeast Regional Stock Assessment Workshop (35th SAW): Stock Assessment Review Commit-tee (SARC) Consensus Summary of Assessments. [By Northeast Regional Stock Assessment Workshop No. 35.]
September 2002.
02-15 Report of the Workshop on Trawl Warp Effects on Fishing Gear Performance, Marine Biological Laboratory, Woods Hole, Massachusetts, October 2-3, 2002. [By Workshop on Trawl Warp Effects on Fishing Gear Performance, Marine Biological Laboratory, Woods Hole, Massachusetts, October 2-3, 2002.] October 2002.
02-16 Assessment of 20 Northeast Groundfish Stocks through 2001: A Report of the Groundfish Assessment Review Meeting (GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, October 8-11, 2002. [By Ground-fish Assessment Review Meeting, Northeast Fisheries Science Center, Woods Hole, Massachusetts, October 8-11, 2002.] October 2002.
03-01 Manuscript/Abstract/Webpage Preparation, Review, & Dissemination: NEFSC Authors Guide to Policy, Process, and Procedure. By J.A. Gibson, T.L. Frady, E.L. Kleindinst, and L.S. Garner. January 2003.
03-02 Stock Assessment of Yellowtail Flounder in the Southern New England - Mid-Atlantic Area. By S.X. Cadrin. [A report of Northeast Regional Stock Assessment Workshop No. 36.] February 2003.
03-03 Stock Assessment of Yellowtail Flounder in the Cape Cod - Gulf of Maine Area. By S.X. Cadrin and J. King. [A report of Northeast Regional Stock Assessment Workshop No. 36.] February 2003.
03-04 Report of the 36th Northeast Regional Stock Assessment Workshop (36th SAW): Public Review Workshop. [By Northeast Regional Stock Assessment Workshop No. 36.] February 2003.
03-05 Description of the 2002 Oceanographic Conditions on the Northeast Continental Shelf. By M.H. Taylor, C. Bascunán, and J.P. Manning. March 2003.
Northeast Fisheries Science Center Reference Document 03-06 A Report of the 36th Northeast Regional Stock Assessment Workshop 36th Northeast Regional Stock Assessment Workshop (36th SAW)
Stock Assessment Review Committee (SARC)
Consensus Summary of Assessments U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Northeast Region Northeast Fisheries Science Center Woods Hole, Massachusetts March 2003
Northeast Fisheries Science Center Reference Documents This series is a secondary scientific series designed to assure the long-term documentation and to enable the timely transmission of research results by Center and/or non-Center researchers, where such results bear upon the research mission of the Center (see the outside back cover for the mission statement). These documents receive internal scientific review but no technical or copy editing. The National Marine Fisheries Service does not endorse any proprietary material, process, or product mentioned in these documents.
All documents issued in this series since April 2001, and several documents issued prior to that date, have been copublished in both paper and electronic versions. To access the electronic version of a document in this series, go to http://www.nefsc.noaa.gov/nefsc/publications/series/crdlist.htm. The electronic version will be available in PDF format to permit printing of a paper copy directly from the Internet. If you do not have Internet access, or if a desired document is one of the pre-April 2001 documents available only in the paper version, you can obtain a paper copy by contacting the senior Center author of the desired document. Refer to the title page of the desired document for the senior Center author's name and mailing address. If there is no Center author, or if there is corporate (i.e., non-individualized) authorship, then contact the Center's Woods Hole Laboratory Library (166 Water St., Woods Hole, MA 02543-1026).
This document may be cited as:
Northeast Fisheries Science Center. 2003. Report of the 36th Northeast Regional Stock Assessment Workshop (36th SAW): Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. Doc. 03-06; 453 p. Available from: National Marine Fisheries Service, 166 Water Street, Woods Hole, MA 02543-1026.
TABLE OF CONTENTS Meeting Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Agenda and Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 A. YELLOWTAIL FLOUNDER STOCK STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 RESEARCH RECOMMENDATIONS TO BE CARRIED FORWARD. . .11 A1. SOUTHERN NEW ENGLAND/MID-ATLANTIC YELLOWTAIL FLOUNDER INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Management History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Assessment History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 FISHERY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Commercial Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Discarded Catch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 ABUNDANCE AND BIOMASS INDICES . . . . . . . . . . . . . . . . . . . . . . 17 Stock Abundance and Biomass Indices . . . . . . . . . . . . . . . . . . . . 17 MORTALITY AND STOCK SIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Virtual Population Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Biomass Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Biological Reference Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Projections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 WORKSHOP DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Working Group Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Stock Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 SARC DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Sources of Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 iii
TABLES A1.1 - A1.10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 FIGURES A1.1 - A1.18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 A2. CAPE COD/GULF OF MAINE YELLOWTAIL FLOUNDER INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Management History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Assessment History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 FISHERY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Commercial Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Discarded Catch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 ABUNDANCE AND BIOMASS INDICES . . . . . . . . . . . . . . . . . . . . . . . 80 Stock Abundance and Biomass Indices . . . . . . . . . . . . . . . . . . . . . . . 80 MORTALITY AND STOCK SIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Virtual Population Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Biological Reference Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Projections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 WORKING GROUP DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Stock Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Stock Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 SARC DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Sources of Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 TABLES A2.1 - A2.9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 FIGURES A2.1 - A2.20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 B1. SOUTHERN NEW ENGLAND/MID-ATLANTIC WINTER FLOUNDER TERMS OF REFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 iv
STOCK STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Stock Boundaries and Associated Statistical Areas . . . . . . . . . . . . . 142 FISHERY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Sampling Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Landed Age Compositions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Commercial Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Recreational Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Discard Estimates and Age Compositions . . . . . . . . . . . . . . . . . . . . 145 Commercial Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Recreational Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Mean Weights at Age in the Catch . . . . . . . . . . . . . . . . . . . . . . . . . 147 Total Catch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 RESEARCH SURVEY ABUNDANCE AND BIOMASS INDICES . . . . . . . 147 NEFSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Rhode Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Delaware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 ESTIMATES OF MORTALITY AND STOCK SIZE . . . . . . . . . . . . . . . . . . . 151 Natural Mortality and Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Total Mortality from Mark and Recapture Data . . . . . . . . . . . . . . . 152 Virtual Population Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Exploitation Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Fishing Mortality, Spawning Stock Biomass, and Recruitment 154 Retrospective Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Precision of Stock Size, F, and SSB Estimates . . . . . . . . . . . . . 155 BIOLOGICAL REFERENCE POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Yield and SSB per Recruit: Stock Recruitment Model . . . . . . . . . . 155 PROJECTIONS FOR 2002-2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 POTENTIAL SENSITIVITY OF VPA ESTIMATES TO HYPOTHETICAL NEFSC SURVEY ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 v
SARC COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 SOURCES OF UNCERTAINTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 RESEARCH RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 TABLES B1.1 - B1.28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 FIGURES B1.1 - B1.15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 B2. GULF OF MAINE WINTER FLOUNDER TERMS OF REFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 STOCK STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Stock Boundaries and Associated Statistical Areas . . . . . . . . . . . . . . . . . . . . 224 FISHERY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Landed Age Compositions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Commercial Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Recreational Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Discard Estimates and Age Compositions . . . . . . . . . . . . . . . . . . . . 226 Commercial Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Recreational Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 Mean Weights at Age in the Catch . . . . . . . . . . . . . . . . . . . . . . . . . 229 Total Catch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 RESEARCH SURVEY ABUNDANCE AND BIOMASS INDICES . . . . . . . 228 Research Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 ESTIMATES OF MORTALITY AND STOCK SIZE . . . . . . . . . . . . . . . . . . . 229 Natural Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 Virtual Population Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 VPA Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Fishing Mortality, Spawning Stock Biomass, and Recruitment . . . 231 vi
Retrospective Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 Precision of Stock Size, F, and SSB Estimates . . . . . . . . . . . . . . . . 232 BIOLOGICAL REFERENCE POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 Yield and Spawning Biomass per Recruit . . . . . . . . . . . . . . . . . . . . 232 Empirical Nonparametric Approach . . . . . . . . . . . . . . . . . . . . . . . . 233 Parametric Model Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 PROJECTIONS FOR 2002-2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 Parametric Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 SARC COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 SOURCES OF UNCERTAINTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 RESEARCH RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 TABLES B2.1 - B2.49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 FIGURES B2.1 - B2.31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 C. NORTHERN SHRIMP TERMS OF REFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317 Fishery Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 Habitat Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Commercial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Data Collection Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 vii
Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Commercial Discards and Bycatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322 Commercial Catch Rates and Fishing Effort . . . . . . . . . . . . . . . . . . . . 322 Fishery Selectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Recreational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Fishery-Independent Survey Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Maine Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Groundfish Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 NSTC Shrimp Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 Biomass Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 ABUNDANCE AND FISHING MORTALITY ESTIMATES . . . . . . . . . . . 327 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 Retrospective Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 Confirmatory Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 Biological Reference Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 Recommendation and Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 Evaluation of Current Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334 ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334 SARC COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 Sources of Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 SARC Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 TABLES C1a - C11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 FIGURES C1 - C23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355 D. STRIPED BASS CATCH-AGE BASED VPA ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 Commercial Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 Recreational Fishery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388 Total Catch at Age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388 Indices of Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 Fishery Independent Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 viii
Fishery Dependent Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 Weight at Age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 VIRTUAL POPULATION ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 Catch at Age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 ADAPT Model Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 Model Fit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 Fishing Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Partial Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Population Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Spawning Stock Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Retrospective Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 TAGGING PROGRAM ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Description of Tagging Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Analysis Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394 Trends in Encounter and Exploitation Rates . . . . . . . . . . . . . . . . . . . . 396 STATUS OF INDIVIDUAL STOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 Chesapeake Bay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 Fishing Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 Spawning Stock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Hudson River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Fishing Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Spawning Stock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Delaware Bay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Fishing Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Spawning Stock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 VPA Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 Tag Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 Tag-VPA F Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 CONCERNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 ix
SARC COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 VPA Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 Tag Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402 Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403 VPA TABLES AND FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 TABLES D1 - D19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 FIGURES D1 - D23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418 TAGGING SEGMENT TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431 TABLES D20 - D35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431 FIGURES D24 - D26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 x
MEETING OVERVIEW The Stock Assessment Review Committee (SARC) meeting of the 36th Northeast Regional Stock Assessment Workshop (36th SAW) was held in the Aquarium Conference Room of the Northeast Fisheries Science Centers Woods Hole Laboratory, Woods Hole, MA December 2-6, 2002. The SARC Chairman was Dr. Andrew Payne, CEFAS, UK (CIE). Members of the SARC included scientists from the NEFSC, the NMFSs Northeast Regional Office, the New England Fishery Management Council (MAFMC), Atlantic States Marine Fisheries Commission (ASMFC), State of Maryland, Canadas Department of Fisheries and Oceans (DFO), and the SEFSCs Beaufort NC laboratory (Table 1). In addition, 39 other persons attended some or all of the meeting (Table 2). The meeting agenda is presented in Table 3.
Table 1. SAW-36th SARC Composition.
Andrew Payne (CEFAS, Lowestoft, UK; CIE), Chairman Northeast Fishery Science Center:
Jon Brodziak Chris Legault Richard Pace Anne Richards Regional Fishery Management Councils:
Andy Applegate, NEFMC Atlantic States Marine Fisheries Commission/States:
Laura Lee, ASMFC Paul Piavis, MD Other experts:
Jerome Hermsen, NMFS, Gloucester Heath Stone, DFO, St. Andrews John Wheeler, DFO, Newfoundland; CIE Erik Williams, SEFSC, Beaufort 36th SAW Consensus Summary 1
Table 2. List of Participants.
NMFS, Northeast Fisheries Science Center MAFMC/ASMFC/States/Industry Almeida, Frank Carmichael, John - NC DMF Boreman, John Caruso, Paul - MA DMF Burnett, Jay Correia, Steve - MA DMF Cadrin, Steve Gamble, Megan - ASMFC Col, Laurel Glenn, Bob - MA DMR Idoine, Josef Hunter, Margaret - Maine DMR Jearld, Ambrose Kelly, Steve - REMSA Mayo, Ralph King, Jeremy - MA DMF McHugh, Nancy Kuzirian, Alan - MBL Moser, Joshua Lazar, Najih - RI DFW Murawski, Steve Lewis, Michael - ASMFC Nitshcke, Paul Lovett, Katie - NMFS O'Brien, Loretta McNamee, Jason - RI DEM Serchuk, Fred Munger, Lydia - ASMFC Shepherd, Gary O'Shea, Vincent - ASMFC Smith, Pie Quinlan, John - Rutgers IMCS Smith, Terry Sharov, Alexei - MD DNR Sosebee, Katherine Welch, Stuart - U.S.G.S Sutherland, Sandra Terceiro, Mark Thompson, Michele 2 36th SAW Consensus Summary
Table 3. Agenda of the 36th Northeast Regional Stock Assessment Workshop (SAW-36) Stock Assessment Review Committee (SARC) Meeting Aquarium Conference Room - NEFSC Woods Hole Laboratory Woods Hole, Massachusetts 2 - 6 December, 2002 TOPIC WORKING GROUP SARC LEADER RAPPORTEUR
& PRESENTER(S)
MONDAY, 2 December (1:00 - 5:00 PM)..................................................................................
Opening Welcome Terry Smith, SAW Chairman P. Smith Introduction Andy Payne, SARC Chairman Yellowtail flounder (A) SAW Southern Demersal Working Group S. Cadrin H. Stone R. Mayo TUESDAY, 3 December (8:30 AM - 5:00 PM)..........................................................................
SNE/MA winter flounder (B1) ASMFC winter flounder technical committee M. Terceiro J. Wheeler P. Nitschke Gulf of Maine winter flounder (B2) ASMFC winter flounder technical committee P. Nitschke E. Williams M. Terceiro Northern shrimp (C) ASMFC northern shrimp technical committee M. Hunter L. Lee R. Glenn Informal reception (6:00 PM) at SWOPE Building (Marine Biological Laboratory)
WEDNESDAY, 4 December (8:30 AM - 5:00 PM).....................................................................
SNE/MA yellowtail flounder (A1) SAW Southern Demersal Working Group S. Cadrin H. Stone S. Wigley Cape Cod yellowtail flounder (A2) SAW Southern Demersal Working Group S. Cadrin A. Applegate J. King Atlantic striped bass (D) ASMFC striped bass technical committee A. Sharov/ P. Piavis M. Gamble S. Welch THURSDAY, 5 December (8:30 AM - 5:00 PM).........................................................................
Review Advisory Reports and Consensus Summary Sections for the SARC Report FRIDAY, 6 December (8:30 AM - 5:00 PM)..............................................................................
SARC comments, research recommendations, and 2nd drafts of Advisory Reports Other business P. Smith 36th SAW Consensus Summary 3
The Process The Northeast Regional Coordinating Council, which guides the SAW process, is composed of the chief executives of the five partner organizations (NMFS/NEFSC, NMFS/NER, NEFMC, MAFMC, ASMFC). Working groups assemble the data for assessments, decide on methodology, and prepare documents for SARC review. The SARC members have a dual role n panelists are both reviewers of assessments and drafters of management advice. As products of the meeting, the Committee prepares two reports: a summary of the assessments with advice for fishery managers known as the Advisory Report on Stock Status; and a more detailed report of the assessment, results, discussions and recommendations known as the Consensus Summary of Assessments (this report).
Assessments for SARC review were prepared at meetings listed in Table 4.
Table 4. SAW-36 Working Group meetings and participants.
Working Group and Participants Stock/Species Meeting Date SAW Southern Demersal Subcommittee Yellowtail flounder August 29, 2002 stock structure Frank Almeida NEFSC Jon Brodziak NEFSC Steve Cadrin NEFSC Hemant Chikarmane MBL Laurel Col NEFSC Alexandra Hangsterfer MBL Jeremy King MADMF Alan Kuzirian MBL Chris Legault NEFSC Ralph Mayo NEFSC Tom Nies NEFMC Loretta O'Brien NEFSC Bill Overholtz NEFSC Paul Rago NEFSC Tim Sheehan NEFSC Vaughn Silva NEFSC Sandy Sutherland NEFSC Mark Terceiro, chair NEFSC Michelle Thompson NEFSC Susan Wigley NEFSC 4 36th SAW Consensus Summary
Table 4. (cont.) SAW-36 Working Group meetings and participants.
Working Group and Participants Stock/Species Meeting Date SNE/MA yellowtail flounder Sept. 30 - October 4, 2002 CC/GOM yellowtail flounder Steve Cadrin NEFSC Steve Correia MA DMF Jeremy King MA DMF Gary Shepherd NEFSC Kathy Sosebee NEFSC Mark Terceiro, chair NEFSC ASMFC Winter Flounder Technical Committee SNE/MA winter flounder September 24-25, GOM winter flounder 2002 Jay Burnett NEFSC Steve Cadrin NEFSC Steve Correia MA DMF, Chair Laura Lee ASMFC, RIDMF Chris Legault NEFSC Anne Mooney NY DEC Lydia Munger ASMFC Paul Nitschke NEFSC Sally Sherman ME DMR David Simpson CT DEP Kathy Sosebee NEFSC Mark Terceiro NEFSC Susan Wigley NEFSC ASMFC Northern Shrimp Technical Committee Northern Shrimp May 15, 2002 September 23-24, 2002 Robert Glenn MA DMF Margaret Hunter, chair ME DMR Josef Idoine NEFSC Clare McBane NH F&G 36th SAW Consensus Summary 5
Table 4. (cont.) SAW-36 Working Group meetings and participants.
Working Group and Participants Stock/Species Meeting Date ASMFC Atlantic Striped Bass Tagging. Committee Linthicum, MD July 23-24, 2002 Robert Beal ASMFC Megan Gamble ASMFC Bob Harris VIMS Desmond Kahn DE DFW Tina McCrobie USFWS Kim McKown NYS DEC Vic Vecchio NYS DEC Beth Versak MD DNR Stuart Welch USGS, WVU ASMFC Striped Bass Technical Committee Linthicum, MD September 10-12, 2002 Mike Armstrong MA DMF Tom Baum NJ DFW Robert Beal ASMFC John Carmichael NC DMF Vic Crecco CT DMF Megan Gamble ASMFC Mark Gibson RI DFW Doug Grout NH DFW Phil Jones MD DNR Desmond Kahn DE DFW Kim McKown NYS DEC Gary Nelson MA DMF Rob OReilly VRMC Alexi Sharov MD DNR Gary Shepherd NEFSC Tom Squiers ME DMR 6 36th SAW Consensus Summary
Agenda and Reports The 36th SARC included presentations on assessments for yellowtail flounder (two stocks), winter flounder (two stocks), and northern shrimp as well as a presentation on assessment methodologies for striped bass. Prior to the presentation and discussion of individual yellowtail flounder stock assessments, the SARC discussed the issue of stock identification for the species. Information was offered by the SAW southern demersal group that led the SARC to conclude that, for assessment purposes, three stocks be classified: Southern New England/Mid-Atlantic (SNE/MA), Georges Bank, and Cape Cod/Gulf of Maine (CC/GOM). Assessments for the SNE/MA and CC/GOM stocks were then reviewed by the panel. The two winter flounder stocks assessed and reviewed by the panel are the Southern New England/Mid-Atlantic stock (SNE/MA) (as previously defined) and the Gulf of Maine stock (previously defined). The GOM winter flounder assessment was the first analytical assessment (VPA via ADAPT) offered for the stock. The winter flounder assessments were prepared by the ASMFCs winter flounder technical committee as was the assessment for northern shrimp.
The striped bass information reviewed by the SARC was not an assessment, per se, but rather materials to address a set of questions (Terms of Reference) which related to specific issues of assessment methodology offered by the ASMFC.
SARC documentation includes two reports: one containing the assessments, SARC comments, and research recommendations (the Consensus Summary Report), and another produced in a standard format which includes information on stock status and management advice (Advisory Report). The draft reports were provided to the NEFMC, MAFMC and ASMFC in January. Presentations to the Councils and Commissions took place in January and February 2003 (MAFMC, 23 January, Atlantic City; NEFMC, 29 January, Portsmouth NH; ASMFC, 25 February, Crystal City VA). Following review by the Councils and Commission, the documents are finalized and published in the NEFSC Reference Document series as the 36th SARC Consensus Summary of Assessments (this report) and the 36th SAW Public Review Workshop Report (which includes the final version of the Advisory Report).
A chart of US commercial statistical areas used to report landings in the Northwest Atlantic is presented in Figure 1. A chart showing the sampling strata used in NEFSC bottom trawls surveys is presented in Figure 2.
36th SAW Consensus Summary 7
Figure 1. Statistical areas used for catch monitoring in offshore fisheries in the Northeast United States.
8 36th SAW Consensus Summary
Figure 2. Offshore sampling strata used in NEFSC bottom trawl surveys.
36th SAW Consensus Summary 9
A. YELLOWTAIL FLOUNDER Stock Structure The SARC reviewed a summary of available information on stock structure of yellowtail flounder in the Northwest Atlantic, with a focus on resources off the northeastern United States.
Following an extensive review of the literature on stock identification, the SARC was presented with a summary of a series of studies covering spatial distribution patterns, geographic variation in growth and maturity, morphometric variation, and larval transport. At present, yellowtail flounder off the northeast coast of the United States are managed as four units: Georges Bank, Cape Cod, Southern New England, and Mid-Atlantic. In addition, the resource is distributed in the western Gulf of Maine, primarily in statistical area 513 adjacent to the Cape Cod management unit. Assessment of the Georges Bank, Southern New England, and Cape Cod stocks are carried out analytically through Virtual Population Analysis (VPA) and/or Biomass Dynamics Models (ASPIC), while the status of the Mid-Atlantic stock is evaluated using research survey index proxies. There has been no analytical assessment of the Gulf of Maine resource.
Most scientific evidence, including tagging studies, growth and maturity rates, and larval transport suggests that yellowtail flounder on Georges Bank are distinct from those in adjacent areas. However, there appears to be a considerable degree of mixing and similarities in biological characteristics between the southern New England and Mid-Atlantic stock units. In the past, the two units were considered to be a single stock, and were apparently split for ICNAF jurisdictional, rather than biological reasons. Although data on stock structure in the Gulf of Maine are sparse, the available information suggests that there is no basis to maintain a distinction between the Cape Cod stock unit and the remaining distribution of the resource in the Gulf of Maine.
The SARC then considered a proposal by the Southern Demersal Working Group to define three stock units: Georges Bank, Southern New England/Mid-Atlantic, and Cape Cod/Gulf of Maine.
Although the literature review and recent studies are comprehensive, there remain several areas of concern. Many conclusions were based on differences in biological characteristics that may simply reflect different environmental regimes in the various locations or changes in exploitation over time. Regardless of the mechanism, differences in growth and maturity are maintained because there is a significant degree of geographic isolation, particularly between the Georges Bank stock and those to the west. However, there are no such physical barriers between the southern New England and Mid-Atlantic areas and there appears to be substantial movement across the existing boundary between the management units for these two stocks.
The relevance of the historical tagging experiments is also an area of concern. The tag returns from these earlier studies were not adjusted for fishing effort, and the tag release sites (often on 10 36th SAW Consensus Summary
the boundary of the existing management units) and time at large was not considered in the original analyses by Royce et al. (1959) and Lux (1963) and in the recent review of stock structure. The available information on tagging is also somewhat dated and may not represent current environmental and stock conditions. In the case of the Mid-Atlantic tagging experiment, the number of tag returns was relatively low (n = 64 recaptures off Southern New England), and release sites may not represent the distribution of yellowtail flounder in the Mid Atlantic region, particularly off New Jersey and Delaware.
In all cases, there must be evidence that the proposed stock units are self-sustaining. This may be problematic for the Cape Cod stock unit, whether or not it is combined with the remaining Gulf of Maine area, because there appears to be little evidence of egg and larval production in this area.
The SARC endorsed the conclusions of the Southern Demersal Working Group to conduct assessments of yellowtail flounder based on the following stock units (Figure A1):
- Georges Bank
- Southern New England/Mid-Atlantic
- Cape Cod/Gulf of Maine.
Research Recommendations to be carried forward.
Further investigation should be carried out to evaluate the degree of mixing between the Georges Bank and Cape Cod stocks of yellowtail flounder.
Several suggestions were made to refine the analysis of stock boundaries, including: 1) evaluating the spatial scale at which data are presented for distribution of life history stages, 2) incorporating information on larval size composition to better delineate possible spawning areas, and 3) performing statistical tests for differences in biological characteristics.
36th SAW Consensus Summary 11
Figure A.1. Revised stock boundaries of yellowtail flounder off the northeastern U.S.
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A1. SOUTHERN NEW ENGLAND - MID ATLANTIC YELLOWTAIL FLOUNDER INTRODUCTION Yellowtail flounder, Limanda ferruginea, inhabit relatively shallow waters (20-100 m) of the northwest Atlantic from Labrador to Chesapeake Bay (Bigelow and Schroeder 1953, Scott and Scott 1988, Collette and Klein-MacPhee 2002). A fishery for yellowtail flounder developed off southern New England in the 1930s, coincident with the increased use of otter trawls, a decline in winter flounder abundance, and demand for food products during World War II (Scott 1954, Royce et al. 1959).
The available information on yellowtail flounder stock structure off the northeast U.S.
indicates separate stocks on Georges Bank, off Cape Cod, and from southern New England to the Mid-Atlantic Bight. Distributional analyses indicate a relatively continuous distribution from the Mid Atlantic Bight to Nantucket Shoals, a concentration on Georges Bank, and a relatively separate concentration off Cape Cod (Royce et al.
1959). Geographic patterns of landings over time suggest that yellowtail resources on Georges Bank on off southern New England are separate harvest stocks (McBride and Brown 1980). Geographic variation indicates that yellowtail off Cape Cod comprise a separate phenotypic stock than resources to the south (Begg et al. 1999). Tagging data indicate less than 3% dispersion from Cape Cod, Georges Bank and southern New England fishing grounds, but substantial movement from the Mid Atlantic to southern New England (Royce et al. 1959, Lux 1963). Descriptive information on early life history stages and circulation patterns suggest that yellowtail spawn in hydrographic retention areas, but there may be some advection of eggs and larvae from Georges Bank and Cape Cod to southern New England and the Mid Atlantic Bight (Sinclair 1988). In conclusion, yellowtail flounder on Georges Bank appear to be a separate harvest stock, yellowtail off Cape Cod can be considered a separate phenotypic stock (with some question on the northern boundary of the stock area), but there is little evidence supporting separate stocks in southern New England and the Mid Atlantic Bight.
Management History From 1950 to 1977, the International Commission for the Northwest Atlantic Fisheries managed yellowtail flounder resources in southern New England, Georges Bank and the Gulf of Maine (i.e., in ICNAF subarea 5). Gear restrictions and total allowable catch were the primary management strategies of ICNAF, but minimum fish size, fishing effort and closed area and season regulations were also regulated. Minimum trawl mesh size was 114 mm in the 1950s and 1960s. National catch quotas were implemented for southern New England yellowtail flounder from 1971 to 1976, but these were exceeded in most years.
Following the implementation of the Magnuson Fisheries Conservation and Management Act (FCMA) in 1976, U.S. yellowtail resources have been managed by the New England Fisheries Management Council (Table A1.1). Groundfish regulations included minimum cod end mesh size, minimum fish size, seasonal area closures, mandatory reporting, trip 36th SARC Consensus Summary 13
limits and annual quotas. Minimum size for yellowtail was increased from 28cm in 1982 to 30cm in 1986 and 33cm in 1989. Minimum mesh size increased from 140 mm in 1991 (diamond and square mesh) to 140mm diamond-152mm square in 1994 and to 165mm in 1999. A large area south of Nantucket Shoals was closed to fishing since December 1994. Scallop dredge vessels were limited to possession of 136kg of yellowtail flounder since 1996, and in 1999 minimum twine top mesh was increased from 203mm to 254mm to reduce yellowtail bycatch.
Assessment History The first quantitative stock assessment of yellowtail flounder was on the southern New England - Mid Atlantic resource and fishery. Royce et al. (1959) evaluated landings, length and age composition, effort, and tagging data to conclude that fishing mortality was approximately 0.30 in the 1940s. However, retrospective estimates of F during the 1940s were substantially greater (approximately 0.6, Lux 1969). Lux (1964) concluded that the stock was not overfished during the 1950s, but age-based mortality estimates for the 1960s were high (Lux 19671, 1969).
Subsequent assessments of yellowtail flounder in the southern New England area excluded Mid-Atlantic catch and survey data, but indicated increasing F and declining stock size in the late 1960s (Brown and Hennemuth 1971a, 1971b; Pentilla and Brown 1973). Starting in 1974, Mid Atlantic and southern New England yellowtail resources were treated as separate assessment and management units, but analyses for each area indicated high mortality and low stock size in the 1970s (Parrack 1974, Sissenwine et al.
1978, McBride and Sissenwine 1979, McBride et al. 1980, Clark et al. 1981). In the early 1980s, there was indication of strong recruitment of yellowtail from surveys and commercial catches in both southern New England and Mid Atlantic areas, but discard rates were high and F exceeded Fmax in southern New England (McBride and Clark 1983, Clark et al. 1984, NEFC 1986).
Assessment methods used for southern New England yellowtail progressed to a calibrated VPA in the late 1980s. The 1988 assessment indicated high F in the 1970s and early 1980s and a strong 1980 cohort (F=0.60-1.48; NEFC 1989). Later stock assessments showed another dominant cohort spawned in 1987, but F continually increased through the 1980s, and the stock was depleted to record low biomass in the early 1990s (Conser et al. 1991, Rago et al. 1994). The VPA-based assessment of southern New England yellowtail was updated annually from 1997 to 1999, and assessments indicated a reduction in F in the late 1990s, but little rebuilding of stock biomass (NEFSC 1997, 1998; Cadrin 2000). In 2000, an updated VPA was attempted, but was rejected as a basis for management advice because sampling in 1999 was inadequate to estimate catch at age reliably (Cadrin 2001b). Therefore, recent assessments of southern New England yellowtail have been based on projections of observed catch from the 1999 VPA (Cadrin 2001b, NEFSC 2002). An updated assessment of the southern New England yellowtail flounder stock was prepared 1
Although Lux (1967) is titled, Landings per unit effort, age composition and total mortality of yellowtail flounder (Limanda ferruginea) in subarea 5Z, the southern New England analyses also include catch and effort data from statistical area 6.
14 36th SAW Consensus Summary
concurrently with this assessment for the Groundfish Assessment Review Meeting (Cadrin 2002b).
An analytical assessment of Mid Atlantic yellowtail flounder has not been developed, and management advice has been based on descriptive summaries of landings and survey data. Assessments of the Mid Atlantic yellowtail resource indicated similar trends in catch and survey indices as in southern New England (NEFC 1987, 1988; NEFSC 1991, 1992, 1993; Rago 1995; Overholtz and Cadrin 1998). Based on survey biomass and exploitation ratios, the Mid Atlantic yellowtail resource was 2% of the BMSY proxy, and the exploitation rate greatly exceeded the FMSY proxy (Cadrin 2001a). An updated assessment of the Mid Atlantic yellowtail flounder stock was prepared concurrently with this assessment for the Groundfish Assessment Review Meeting (Cadrin 2002a).
FISHERY DATA Commercial Landings Commercial statistics for southern New England yellowtail flounder are from statistical areas 526, 537, 538, and 539, and mid Atlantic yellowtail are from statistical areas 611-623 (Figure A1.1). U.S. commercial landings of yellowtail flounder were derived from dealer weighout reports and canvas data according to historical assessment reports (Royce et al. 1959, Brown and Hennemuth 1971, Sissenwine et al. 1978, McBride et al.
1980, McBride and Clark 1983, NEFC 1986, McBride 1989, Rago et al. 1994). Total Mid Atlantic landings from canvas data were allocated to market category according to annual proportions in the weighout database. Previous to 1994, landings were allocated to statistical area, month, and gear type according to interview data collected by port agents (Burns et al. 1983). For 1994, landings reported by dealers were allocated to stock area using fishing vessel logbook data, by fishing gear, port, and season (Wigley, et al.
1998). For 1995-1997, dealers reported landings were prorated to stock area using a modified proration that included dealer codes (NEFSC 1998).
Landings generally increased in southern New England during the 1930s and early 1940s and the fishery expanded to the Mid Atlantic in the early 1940s, with landings of 28,000mt in 1942 (Table A1.2, Figure A1.2). Annual landings were around 10,000mt from 1943 to 1948 with approximately 10% from the Mid Atlantic. A domestic industrial fishery developed in the late 1940s. Landings decreased to less than 2,000mt in the mid 1950s. Landings increased in southern New England in the late 1950s and again expanded to the Mid Atlantic in the 1960s. A distant water fishery developed in the 1960s and total annual landings were greater than 20,000mt from 1963 to 1970. The industrial and foreign fisheries were discontinued in the early 1970s. Landings generally decreased since the 1970s, with temporary increases in the early 1980s and early 1990s.
Landings in 1995 were a record low 200 mt, and the proportion of landings from the Mid Atlantic generally increased from approximately 10% in the early 1990s to greater than 20% (e.g., in 1997, 70% of landings in the stock area came from the Mid Atlantic).
Landings slightly increased to greater than 1,000mt per year since 1999.
36th SARC Consensus Summary 15
A summary of port samples (each consisting of approximately 100 lengths and 1 age sample per cm) are listed in Table A1.3. Landings at age were derived by geographic region, half-year and market category, when possible. Landings at age of southern New England yellowtail flounder are described in previous assessment documents (Conser et al. 1991; Rago et al. 1994; NEFSC 1997, 1998; Cadrin 2000; Cadrin 2002b). Mid Atlantic landings were not sampled in several half-year periods, and age distributions of southern New England landings were assumed for Mid Atlantic landings in those periods by quarter and market category (2nd half of 1975, 2nd half of 1981, 2nd half of 1986, 2nd half of 1987, 2nd half of 1988, 1st half of 1989, 2nd half of 1990), or by half and market category for 2000 and 2001. Landings at age and landed mean weights at age are reported in Table A1.4. In the early 1970s a substantial portion of landings were from older fish (e.g., 17% of 1973 landings were age-6 or older), but the age distribution of landings rapidly truncated, and the portion of age 6+ fish has generally been less than 3%
since 1977.
Discarded Catch Estimates of discards for the southern New England - Mid Atlantic yellowtail fishery for 1963-1969 were derived from interviews with vessel captains; historical discards were approximated by Brown and Hennemuth (1971a) from the 1963-1969 average discard rate (Table A1.5). Discards for 1970-1977 were also based on interview data, however yellowtail interview data were suspect from 1978 to 1982 when trip limits were imposed (McBride et al. 1980, Clark et al. 1981). Discards during 1978-1982 were estimated from observer data when available (Sissenwine et al. 1978), derived directly from field selectivity studies (McBride et al. 1980), or from application of selectivity estimates to survey size frequencies (McBride and Clark 1983). Discards for 1983 were from interview data (Clark et al. 1984). Discards at age from southern New England, 1984-1993 were from a combination of sea sampling, interviews and survey data (Conser et al.
1991, Rago et al. 1994). Discards for 1994-2001 were derived from vessel logbooks (NEFSC 1997, 1998; Cadrin 2000). Updated discard estimates for southern New England are listed in Table A1.5a. Discards of Mid Atlantic yellowtail were from interview data for 1984-1993. Mid Atlantic discards for 1994-2001 were derived from logbook data by gear for all trips that reported discards of any species (NEFSC 1998, Table A1.5b).
Discarded catch accounted for an average of 30% of total catch annually, but appears to have decreased to approximately 10% since 1995. In 1969, discards peaked at 24,000mt, 40% of the total catch that year. A substantial portion of recent discards are from the scallop dredge fishery.
Discards at age were estimated from observer lengths (Table A1.3) and survey ages 1994-2001. Discards at age of southern New England yellowtail flounder are described in previous assessment documents (Conser et al. 1991; Rago et al. 1994; NEFSC 1997, 1998; Cadrin 2000; Cadrin 2002b). Age distribution of discards in southern New England were assumed for Mid Atlantic discards for 1973 to 1993 (Table A1.6).
Discards were primarily ages 1 and 2 during from the 1970s through the early 1990s, but shifted to age 2 and 3 in the early 1990s, coincident with regulated mesh size increases.
16 36th SAW Consensus Summary
Estimates of total catch at age reflect the landings at age in that they indicate a relatively wide age distribution in the catch in the early 1970s (e.g., approximately 10% of the catch was age-6 or older from 1973 to 1975; Figure A1.3, Appendix A). Subsequent catch at age was dominated by the 1980 and 1987 cohorts, but few fish older than age-6 contributed to the catch. Mean weights at age of older fish (age 4+) generally increased in the mid 1970s, were relatively light during the mid 1980s, and generally increased in recent years (Figure A1.4). Mean weight of age-1 yellowtail generally decreased in the 1990s, presumably from discards of small yellowtail in the scallop fishery.
ABUNDANCE AND BIOMASS INDICES Stock Abundance and Biomass Indices The NEFSC spring and autumn bottom trawl surveys have sampled offshore strata since 1963 and 1968, respectively (Despres et al. 1988). However, the southern-most offshore strata (61-76) were not sampled until 1967. Therefore southern strata were included in the spring survey index, 1968-2002 and the winter survey index 1992-2002 (strata 1, 2, 5, 6, 9, 10, 69, 73, 74; Figure A1.5), but excluded from the fall survey index, 1963-2001 (strata 1, 2, 5, 6, 9, 10). Nearly all yellowtail caught by the survey in the southern New England - Mid Atlantic stock area (99%) are in the spring and winter strata sets. The strata set for the NEFSC scallop survey was determined as all strata that were consistently sampled in the stock area (14, 15, 18, 19, 22-28, 30, 31, 33, 35, and 46).
Indices of abundance and biomass indicate relatively high stock size in the 1960s and early 1970s, followed by a rapid decrease in the mid 1970s (Table A1.6, Figure A1.6).
Stock biomass increased temporarily in the early and late 1980s with the recruitment of the strong 1980 and 1987 cohorts. Recent distributions of yellowtail catches in surveys are illustrated in Figure A1.7. The average portion of yellowtail biomass in the Mid Atlantic region has been 45% of the total southern New England - Mid Atlantic yellowtail biomass (Figure A1.8). Age distribution of yellowtail in surveys indicates abundant cohorts in the 1960s and early 1970s, strong year classes in 1980 and 1987, and relatively truncated age structure since the early 1970s (Table A1.7, Figure A1.9).
Correspondence among survey indices was assessed using correlations among normalized observations for the VPA time series 1973-2001 [Ln(x/mean); Table A1.8].
Normalized indices of catch per tow at age are illustrated in Figure A1.10. Correlations among survey series were generally low for the winter survey, particularly for older ages, presumably because it is a short series with little contrast. Correlations between spring and fall survey series were strongest at ages 2-4 (r=0.71-0.82).
36th SARC Consensus Summary 17
MORTALITY AND STOCK SIZE Virtual Population Analysis Abundance estimates from virtual population analysis of catch at age of age-1 to age-7+,
1973-2001, were calibrated using an ADAPT algorithm (Gavaris 1988) that estimated age 2-5 survivors in 2002 and survey catchability coefficients (q) using nonlinear least squares of survey observation errors. Abundance at age was calibrated with survey indices of abundance: spring survey indices (age-1 to age-7+) and winter indices (age-1 to age-5) were calibrated to January abundance, and fall survey indices (age-1 to age-7+)
were calibrated to mean abundance. The instantaneous rate of natural mortality (M) was assumed to be 0.2 based on tag returns (Lux 1969), relationships of Z to effort (Brown and Hennemuth 1971a), and the oldest individual sampled in the stock area (age-14).
Although catches of yellowtail older than age-8 are rare in commercial or research catches, the stock has been heavily exploited for seven decades. Maturity at age for southern New England yellowtail flounder was reported by OBrien et al. (1993) from 1985-1990 NEFSC spring survey samples. Model Residuals are plotted in Figure A1.11.
Results show that the stock was abundant in the early 1970s with a relatively wide age structure (11% of the population in 1973 was age 6 or older), but was quickly truncated by the late 1970s (<2% age 6+ from 1978 to 2001; Table A1.9, Figure A1.12c). Fishing mortality generally increase in the 1970s and 1980s to a peak of 2.3 in 1991 and 1992, averaged 1.6 during the 1990s, and appears to have decreased to 0.68 in 2000 and increased to 0.91 in 2001 (Figure A1.12a). Recruitment was generally strong in the 1970s and moderate during the 1980s, with two exceptional year classes in 1980 and 1987. Recruitment has been low during the 1990s. Spawning biomass was high in the early 1970s, decreased in the late 1970s, and increased briefly in the early and late 1980s with recruitment of the 1980 and 1987 cohorts. Spawning biomass decreased to a record low 622mt in 1994, gradually increased to 2,100mt in 2000, and decreased to 1,900mt in 2001. Retrospective analysis indicates a strong pattern of underestimating F, and overestimating SSB in recent years (Figure A1.13).
Biomass Dynamics Given the problems in estimating recent catch at age in the southern New England area (Cadrin 2000) an age-aggregated production model (ASPIC, Prager 1994) was fit to total catch and survey biomass indices. Initial trials did not fit the winter survey biomass series, presumably because it is relatively short and does not have much contrast, nor did the model fit the catch rate data from Lux (1969). Alternative analyses that assumed that stock biomass was at the carrying capacity in 1935 had very similar results.
Results of the biomass dynamics model indicate that biomass decreased during the 1960s and early 1970s to about 10% of the biomass estimated for the early 1960s (Figure A1.14). Similar to the age-based analysis, the biomass dynamics model indicates brief periods of rebuilding in the early and late 1980s and a further decrease to extremely low biomass in the mid 1990s. However, the biomass dynamics model indicates a slightly faster rate of rebuilding in recent years than indicated by the age-based analysis.
18 36th SAW Consensus Summary
Biological Reference Points Yield and biomass per recruit were calculated assuming the observed partial recruitment and mean weight at age for 1994-2001 (Thompson and Bell 1934). Results are reported in Table A1.10 and illustrated in Figure A1.15. Applying the approach used to estimate MSY proxies for southern New England yellowtail (NEFSC 2002), FMSY is approximated as F40% (0.26). The SSBMSY proxy is 69,500mt, calculated as the product of 40%MSP (1.129 kg spawning biomass) and average long-term recruitment (61.57 million). The average long-term recruitment was derived as the fall survey age-1 index divided by the catchability coefficient estimated by ADAPT (8.08E-5). The MSY proxy is 14,200mt, derived as the product of yield per recruit at F40% (0.230 kg) and average recruitment.
Alternatively, SSBMSY and MSY were estimated using stochastic long-term projections assuming recent average weights at age and partial recruitment (1994-2001), and the distribution of long term recruitment. Results suggest that at an F of 0.26, the long-term average catch is 13,100mt, and long-term average SSB is 64,500mt (Figure A1.16) .
For comparison, the estimate of BMSY from biomass dynamics analysis is 104,700mt of total biomass, FMSY is 0.19 on total biomass, and MSY is 20,300mt. The Working Group accepted the deterministic estimates of MSY reference points based on consistency with estimates for other groundfish stocks (NEFSC 2002): FMSY=0.26, SSBMSY= 69,500mt and MSY=14,200mt.
Projections Stochastic age-based projections that assume a 15% reduction in F from 2001 to 2002 and recruitment similar to that experienced in the last decade suggest that the stock cannot rebuild to BMSY by 2009 even if F in 2003-2010 is zero. If the same hindcast recruitment values used to derive the reference points are assumed for projections, there stock is expected to have approximately a 50% chance of rebuilding to SSBMSY by 2009 with an F of 0.08 (Figure A1.17, Appendix A). However, long-term recruitment levels are not likely in the short-term, because SSB is extremely low, and retrospective patterns indicate that projections may be overly optimistic. For comparison, stochastic projections from the biomass dynamics model at status quo F in 2002 and F=0 for 2003-2009 indicate a 25% probability of rebuilding to the ASPIC estimate of BMSY by 2009 (Appendix B).
WORKSHOP DISCUSSION Working Group Discussion Stock Structure - The WG reviewed seven working papers/presentations on yellowtail stock structure. With respect to spatiotemporal patterns of abundance, the WG noted that recruitment trends of Cape Cod and southern New England yellowtail indicated possible autocorrelation, as evidenced by a common series of several years of poor recruitment that might be indicative of a common stock. The WG noted that historical tagging data indicate weak movement between the Cape Cod, Georges Bank, and other areas, but strong mixing between Mid Atlantic and southern New England areas, that might be 36th SARC Consensus Summary 19
indicative of a common Mid Atlantic-southern New England stock. The WG also noted that the fish from the Mid Atlantic and southern New England have concurrent spawning seasons, comparable lengths of 50% Maturity, and similar growth rates, and that detailed distribution plots indicated that most of the Mid Atlantic fish are found in areas closest to the boundary with the Southern New England stock (i.e., area 613). The WG noted that the Mid Atlantic and Southern New England areas were grouped together prior to the early 1970s, when they were separated to conform with ICNAF reporting conventions.
The WG noted limited evidence in the literature to separate Gulf of Maine fish from the Cape Cod stock. The WG supported the major conclusion of working paper A1 that information available from the literature indicates separate yellowtail flounder stocks on Georges Bank, off Cape Cod, and in the Southern New England-Mid Atlantic Bight area.
The WG noted that NEFSC survey stratum 13 (southwestern Georges Bank) appears to be an Aoverlap@ or Atransition@ zone, with peaks in abundance over time that are characteristic of both the Georges Bank and southern New England stocks, and may be inhabited by fish from both stocks during times of abundance. The WG noted that a similar situation may exist in NEFSC stratum 10, adjacent to the Great South Channel.
The WG supported the conclusions of working paper A2 that 1) there are two major groups of NEFSC survey strata based on patterns of abundance over time, with a boundary on southwestern Georges Bank, and 2) the current analyses confirm earlier conclusions of separate Aharvest stocks@ on Georges Bank and off southern New England.
A correlation analysis of survey and catch data by management area generally confirmed the multivariate analysis by stratum. Survey indices and landings were strongly correlated between southern New England and the mid-Atlantic, not correlated between southern New England and Cape Cod or southern New England and Georges Bank, and moderately correlated between Georges Bank and Cape Cod.
The WG noted that previous investigators (e.g., Lux 1963) found no significant differences in meristics (e.g., fin and ray counts) among U.S. stocks, supporting the current morphometric work. The WG also noted that the results of the morphometric work coincides with the differences in growth noted between U.S. and Newfoundland stocks. The WG supported the working paper A4 conclusion that morphometric variation among U.S. yellowtail flounder groups is not sufficient for accurate classification to stock area.
The WG noted that the number of migrants per generation between the yellowtail stock areas, although probably low, is likely sufficient to prevent detection of significant genetic differences using RAPD-PCR. The WG noted that the expression of phenotypic differences may not be evident in the genome, or Mid Atlantic be very difficult to detect (many different primers may have to be tested to find one that isolates the gene responsible for a given phenotypic expression). The WG supported the conclusion of presentation A6 that, at this time, yellowtail flounder stock differentiation must be based on factors other than genetics.
The WG noted that historical stock area determinations included the mid Atlantic area as a part of the southern New England stock (e.g., Royce et al. 1959, Lux 1969) . Mid 20 36th SAW Consensus Summary
Atlantic landings were excluded from assessments of AICNAF Area 5" yellowtail beginning in the early 1970s (e.g., Brown and Hennemuth 1971), apparently to conform to ICNAF jurisdictions and to respond to the concerns of Mid Atlantic fishermen of being subject to the ICNAF regulatory regime. The Mid Atlantic resource was assessed as a separate stock beginning in the mid 1970s/early 1980s (e.g., Parrack 1974, McBride and Brown 1980).
The current work reviewed by the WG indicates a single homogeneous genetic stock of yellowtail flounder on U.S. fishing grounds. Patterns over time in landings and survey indices suggest two harvest stocks with a boundary between Georges Bank and Southern New England. Differences in life history characteristics suggest two phenotypic stocks with a boundary off Cape Cod. The WG noted that the most important potential Amisalignments@ with respect to current or proposed stock definitions are in areas 521, 525, and 526 (and associated NEFSC survey strata 10, 13 and 25), where fish from adjacent stocks may overlap during times of abundance. However, the WG found no strong evidence in patterns of fishery landings, survey abundance indices, or life history parameters to suggest that revision of the current assignment to stock areas of these particular statistical areas or survey strata is appropriate. The WG concluded that current evidence indicates that three stock areas are appropriate for yellowtail flounder: 1) a Georges Bank stock including fish landed from NEFSC statistical areas 522, 525, 551-552, and 561-562, and associated NEFSC survey strata (i.e., the current stock definition used in U.S. and Canadian assessments), 2) a southern New England - Mid Atlantic stock including fish landed from areas 526, 533-539, 541, and 611-639, and associated NEFSC survey strata, and 3) a Cape Cod - Gulf of Maine stock including fish landed from areas 511-521, and associated NEFSC survey strata. Finally, the WG recommends that assessment scientists explore the potential to classify yellowtail in fishery and survey samples to stock in the Aoverlap/transition@ areas based on age structure characteristics.
Stock Assessment The Working Group discussed the quality of historical canvas data and questioned if historical catch may be underreported in the Mid Atlantic region or misallocated from the Mid Atlantic to the southern New England region.
The Group examined three criteria for choosing indices of abundance for the VPA calibration: correlation with other indices, partial variance in an initial calibration that included all indices, and residual patterns. During the time series of the winter survey, 1992-2002, few age 6 and 7+ yellowtail were caught and those two indices accounted for a disproportionately large portion of the total model variance. The Working Group excluded those two indices from the calibration, because they were adding noise to the calibration. However, it was noted that the survey is designed to catch flatfish, and the indices may become useful as age structure rebuilds.
The Working Group discussed the recruitment assumptions for projections. Previous studies found significant effects of temperature on survival ratios, but the reference point working group (NEFSC 2002) found no trend in temperatures for the last decade which would suggest a reason why recruitment has been extremely low since 1987. The Group 36th SARC Consensus Summary 21
noted that the ASPIC model was more optimistic than the VPA in terms of current status, but was not optimistic in terms of projections. ASPIC projections indicate that biomass does not rebuild to Bmsy in 2009 at F=0. By comparison, age-based projections do not rebuild to target in 2009 at F= 0 unless the whole time series of recruitment values, including the hind-cast estimates are used.
The Working Group adopted the approach of the Reference Point Working Group (NEFSC 2002) for estimating MSY reference point proxies. The Group also noted that mean weights at age seem to show density dependence. Therefore, weights may decrease as the stock rebuilds. The Group also decided to account for sampling problems in recent years by averaging mean weights and partial recruitment from as many years as possible (1994-2001) to represent the current fishery in reference point calculations and projections.
SARC DISCUSSION The poor sampling of commercial landings in 1999 for the entire area was considered.
While there is a systematic problem in collecting a biological sample without knowledge of the statistical area from which it came (e.g. the area fished is acquired from the VTR and not from an interview with the captain at the time of landing), in this situation the lack of samples is due to the hit-or-miss nature of sampling low-volume landings (in 1999 the MA landings were just 240 mt). Throughout the entire time period (1973-2001) 15% of the MA cells did not have samples and SNE samples were used to characterize the catch at age. As SNE samples were applied to MA landings in some years, the SARC suggested evaluating the impact of pooling areas using years where adequate samples exist for both areas.
The SARC noted that the discard ratio used to estimate yellowtail flounder discards in the scallop fishery may not be suitable. As the scallop fishery has had trip limit regulations, the discard/kept ratio may not be as appropriate as an effort-based ratio. However, an effort-based ratio, if applied resource-wide, would overestimate discards in areas where scallop effort and yellowtail distribution do not overlap. It was suggested that an effort-based ratio be applied in the MA area, where scallop effort and yellowtail flounder distributions overlap, and a discard/kept ratio in the SNE area, where these distributions do not overlap as much.
The SARC commented on the declining mean weights at age in the commercial catch in recent years. Mean weights at age from the NEFSC survey would be informative in confirming the commercial trends observed.
The spatial coverage of the NEFSC autumn survey was not consistent over the entire time series; from 1963 to 1967 the southernmost strata used to assess the stock were not sampled. Although the restricted spatial coverage will not impact the VPA because the VPA begins in 1973, other analyses, such as hindcast estimates of recruitment and ASPIC, may be impacted. The SARC evaluated the NEFSC autumn survey indices (with 22 36th SAW Consensus Summary
and without strata 69, 73 and 74) and concluded that the trend and magnitude were similar between the two series. The SARC accepted the analyses conducted with the spatially restricted series to gain the benefits of the longer time series.
The SARC discussed the VPA retrospective analysis, which revealed a consistent pattern of underestimating F and overestimating SSB since 1995. It was agreed that the retrospective pattern was a key element to the stock assessment results and that this information should be included in the management advice because the direction of the retrospective pattern changes perspective of stock biomass and fishing mortality from year to year. However, the overfished and overfishing status is not affected by the retrospective bias.
The SARC felt that the YPR-SPR approach was appropriate for estimating biological reference points for this stock. The discussion focused on establishing the most appropriate time series of recruitment. The SARC reviewed SSBMSY and MSY estimates derived from four possible recruitment time series: 1) long-term (1963-2001) average; 2)
VPA time-series (1973-2001) average; 3) last ten years (1992-2001) VPA average; and
- 4) pre-VPA hindcast (1963-1972) average. The average recruitment from the four time series ranged between 6.4 million (last ten years) and 193 million (pre-VPA hindcast) and caused a wide range in the point estimates of SSBMSY and MSY (Figure A1.18). Given the lack of evidence of an ecological regime shift, the SARC concluded that the most credible recruitment time series was the long-term (1963-2001) series. It was also concluded that a range of biological reference points would be useful in providing boundaries about the most credible estimate.
The SARC reviewed a stock-recruitment trajectory plot where estimates from the VPA and the hindcast analysis were represented. It was noted that what appeared to be two outliers in the VPA series would not be considered outliers when the hindcast recruitment estimates were included.
Sources of Uncertainty o Although sampling improved in 2000 and 2001, estimates of previous catch at age (particularly 1999) may be imprecise due to poor sampling intensity. Therefore, VPA- and age-based projections may also be imprecise. Retrospective patterns may indicate inadequate sampling and misallocation of catch at age.
o Retrospective patterns indicate that VPA estimates of biomass and F are likely to be optimistic. Future VPAs may indicate a lower level of SSB and a higher F for 2001 than reported here.
o Estimates of landings and discard ratios since 1994 are based on preliminary logbook data applied on a pro rata basis, and are subject to change.
Research Recommendations o Explore the use of effort-based and discard/kept ratios for the scallop fisheries o Analyze the impacts of applying SNE samples to MA landings for years where adequate samples exists for both areas.
o Consider using a forward projection model that allows for error in catch at age, because of 36th SARC Consensus Summary 23
the extremely poor sampling in 1999 and more flexible assumptions about selectivity.
o Investigate changes in maturity at age over time.
o Examine mean weights at age from surveys to confirm trends observed in the commercial mean weights.
o Incorporate data from the entire stock area for the fall survey calibration index.
o Improve sea sampling coverage for otter trawl and scallop vessels to allow for better estimation of discards.
o Increase the sampling frequency of SNE-MA yellowtail flounder during the bottom trawl surveys.
o Collect adequate numbers of quarterly commercial samples for length and age composition.
REFERENCES Begg, G.A., J.A. Hare, and D.D. Sheehan 1999. The role of life history parameters as indicators of stock structure. Fish. Res. 43: 141-163.
Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fish. Bull. 53: 1-577.
Brown, B.E. and R.C. Hennemuth. 1971a. Assessment of the yellowtail flounder fishery in subarea
- 5. ICNAF Res. Doc. 71/14.
Brown, B.E. and R.C. Hennemuth. 1971b. Prediction of yellowtail flounder population size from pre-recruit catches. ICNAF Res. Doc. 71/115.
Cadrin, S.X. 2000. Southern New England yellowtail flounder. In Assessment of 11 Northeast Groundfish Stocks through 1999. NEFSC Ref. Doc. 00-05: 65-82.
Cadrin, S.X. 2001a. Mid Atlantic yellowtail flounder. In Assessment of 19 Northeast Groundfish Stocks through 2000. NEFSC Ref. Doc. 01-20: 190-194.
Cadrin, S.X. 2001b. Southern New England yellowtail flounder. In Assessment of 19 Northeast Groundfish Stocks through 2000. NEFSC Ref. Doc. 01-20: 54-66.
Cadrin, S.X. 2002a. Mid Atlantic yellowtail flounder. Groundfish Assessment Review Meeting Working Paper Q.
Cadrin, S.X. 2002b. Southern New England yellowtail flounder. Groundfish Assessment Review Meeting Working Paper D.
Clark, S.H., L. OBrien, and R.K. Mayo. 1981. Yellowtail flounder stock status. NEFC Lab. Ref.
Doc. 81-10.
Clark, S.H., M.M. McBride and B. Wells. 1984. Yellowtail flounder assessment update - 1984.
NEFC Lab. Ref. Doc. 84-39.
24 36th SAW Consensus Summary
Collette, B.B. and G. Klein-MacPhee. 2002. Bigelow and Schroeders Fishes of the Gulf of Maine.
Smithsonian Press, Washington, D.C.
Conser, R.J., L. OBrien, and W.J. Overholtz. 1991. An assessment of the southern New England and Georges Bank yellowtail flounder stocks. Appendix to NEFSC Ref. Doc. 91-03.
Despres, L. I., T. R. Azarovitz, and C. J. Byrne. 1988. Twenty-five years of fish surveys in the northwest Atlantic: the NMFS Northeast Fisheries Centers bottom trawl survey program. Mar.
Fish. Rev. 50(4): 69-71.
Gavaris, S. 1988. An adaptive framework for the estimation of population size. CAFSAC Res.
Doc. 88/29.
Lux, F.E. 1964. Landings, fishing effort, and apparent abundance in the yellowtail flounder fishery. ICNAF Res. Bull. No. 1: 5-21.
Lux, F.E. 1967. Landings per unit effort, age composition, and total mortality of yellowtail flounder (Limanda ferruginea) in subarea 5Z. ICNAF Res. Doc. 67/28.
Lux, F.E. 1969. Landings per unit effort, age composition, and total mortality of yellowtail flounder, Limanda ferruginea (Storer), off New England. ICNAF Res. Bul. 6:47-69.
McBride, M.M. and B.E. Brown 1980. The status of the marine fishery resources of the northeastern United States. NOAA Tech. Mem. NMFS-F/NEC-5.
McBride, M.M. and S.H. Clark. 1983. Assessment status of yellowtail flounder (Limanda ferruginea) stocks off the northeastern United States. NEFC Lab. Ref. Doc. 83-32.
McBride, M.M. and M.P. Sissenwine. 1979. Yellowtail flounder (Limanda ferruginea) status of the stocks, February 1979. NEFC Lab. Ref. Doc. 79-06.
McBride, M.M., M.P. Sissenwine, B.E. Brown and L.M. Kerr. 1980. Yellowtail flounder (Limanda ferruginea) status of the stocks, March 1980. NEFC Lab. Ref. Doc. 80-20.
NEFC (Northeast Fisheries Center) 1986. Report of the second NEFC stock assessment workshop (second SAW). NEFC Ref. Doc. 86-09.
NEFC (Northeast Fisheries Center) 1987. Status of the fishery resources off the northeastern United States for 1987. NOAA Tech. Mem NMFS-F/NEC-50.
NEFC (Northeast Fisheries Center) 1988. Status of the fishery resources off the northeastern United States for 1988. NOAA Tech. Mem NMFS-F/NEC-63.
NEFC (Northeast Fisheries Center) 1989. Report of the seventh NEFC stock assessment workshop (seventh SAW). NEFC Ref. Doc. 89-04.
36th SARC Consensus Summary 25
NEFC (Northeast Fisheries Center) 1991. Status of the fishery resources off the northeastern United States for 1990. NOAA Tech. Mem NMFS-F/NEC-81.
NEFSC (Northeast Fisheries Science Center) 1991. Status of the fishery resources off the northeastern United States for 1991. NOAA Tech. Mem NMFS-F/NEC-86.
NEFSC (Northeast Fisheries Science Center) 1992. Status of the fishery resources off the northeastern United States for 1992. NOAA Tech. Mem NMFS-F/NEC-95.
NEFSC (Northeast Fisheries Science Center) 1993. Status of the fishery resources off the northeastern United States for 1993. NOAA Tech. Mem NMFS-F/NEC-101.
NEFSC (Northeast Fisheries Science Center) 1997. 24th northeast regional stock assessment workshop (24th SAW). NEFC Ref. Doc. 97-12.
NEFSC (Northeast Fisheries Science Center) 1998. 27th northeast regional stock assessment workshop (27th SAW). NEFC Ref. Doc. 98-15.
NEFSC (Northeast Fisheries Science Center). 2002. Final report of the Working Group on Re-Evaluation of Biological Reference Points for New England Groundfish. 19 March, 2002.
OBrien, L., J. Burnett, and R.K. Mayo. 1993. Maturation of nineteen species of finfish off the northeast coast of the United States, 1985-1990. NOAA Tech. Rep. NMFS 113.
Overholtz, W. and S.X. Cadrin. 1998. Yellowtail flounder. NOAA Tech. Rep. NMFS-NE-115:
70-74.
Parrack, M. 1974. Status review of ICNAF subarea 5 and statistical area 6 yellowtail flounder stocks. ICNAF Res. Doc. 74/99.
Pentilla, J.A. and B.E. Brown 1973. Total mortality estimated from survey cruise data for two groups of yellowtail flounder in the southern New England and Georges bank Areas (ICNAF Subarea 5). ICNAF Res. Bul. 10: 5-14.
Prager, M.H. 1994. A suite of extensions to a nonequilibrium surplus-production model. Fish.
Bull. 92: 374-389.
Rago, P. 1994. Yellowtail flounder. NOAA Tech. Rep. NMFS-NE-108: 64-68.
Rago, P.J., W.L. Gabriel, and M.C. Lambert. 1994. Assessment of southern New England yellowtail flounder (Pleuronectes ferrugineus), 1993. NEFC Ref. Doc. 94-02.
Royce, W.F., R.J. Buller, and E.D. Premetz. 1959. Decline of the yellowtail flounder (Limanda ferruginea) off New England. Fish. Bull. 146: 169-267.
26 36th SAW Consensus Summary
Sinclair, M. 1988. Marine populations: an essay on population regulation and speciation. Univ.
Washington Press, Seattle.
Sissenwine, M.E., B.E. Brown, and M.M. McBride. 1978. Yellowtail flounder (Limanda ferruginea): status of the stocks. NEFC Lab. Ref. Doc. 78-02.
Thompson, W. F. and F. H. Bell. 1934. Effect of changes in intensity upon total yield and yield per unit of gear. Report of the International Fisheries Commission 8:7-49.
36th SARC Consensus Summary 27
Table A1.1. Management history of southern New England - Mid Atlantic yellowtail flounder.
Year Comments FCMA implemented March 1 1977 Groundfish plan adopts quotas for cod, haddock, yellowtail flounder Interim Groundfish Plan adopted:
1982 11 inch minimum size for yellowtail Scallop FMP implemented Northeast Multispecies FMP adopted:
Minimum size for yellowtail flounder: 12 inches 1986 Seasonal yellowtail closure, March - May, between 69-30 and 72-30W Closed area I and II continued as spawning closures on GB Amendment 2:
1989 Yellowtail minimum size increased to 13 inches Seasonal large mesh area off Nantucket Shoals to protect cod Amendment 4:
Tightened restrictions on carrying small mesh while in Regulated Mesh Areas 1991 Minimum mesh size of 5 1/2 inches in Southern New England yellowtail area Amendment 5 and emergency regulations:
December: NLCA closed year round, including to scallop dredges DAS limits for most vessels West of 72-30W. Mesh determined by mesh requirements of summer flounder fishery (5 1/2 inch 1994 diamond or 6 inch square)
Established Southern New England RMA, mesh of 5 1/2 inch diamond square, to increase to 5 1/2 inch diamond or 6 inch square in year 2. Area from approximately 69-40W to 72-30 W.
Scallop Amendment 4: adopted permit moratorium, effort control/DAS program, 5.5 inch twine top minimum, and crew limits Amendment 7 Extended DAS limits to most vessels Limited possession of groundfish by scallop vessels to 300 pounds of regulated multispecies 1996 Established criteria for exempted fisheries Mid-Atlantic regulated mesh area fisheries exempt from bycatch certification Framework 27: (May 1) 1999 Increased square mesh minimum size to 6 1/2 inches in GOM/GB/SNE Regulated mesh areas Framework 29: (June)
Amendment 9: (November): Revised overfishing definitions Scallop Framework 11: 10 inch minimum twine top mesh Scallop Framework 13: Scallop vessel closed area access programs with yellowtail bycatch limits Adopted management measures for small-mesh multispecies, establishing minimum mesh sizes and 2000 trip/possession limits to reduce mortality on silver, red, and offshore hake 28 36th SAW Consensus Summary
Table A1.2. Southern New England-mid Atlantic yellowtail flounder catch (kt).
Mid-Atlantic Southern New England U.S. U.S. foreign U.S. U.S. industrial foreign year landings discards catch landings discards landings landings total 1960 0.0 0.0 0.0 8.3 3.2 0.5 0.0 12.0 1961 0.0 0.0 0.0 12.3 4.7 0.7 0.0 17.7 1962 0.0 0.0 0.0 13.3 5.3 0.2 0.0 18.8 1963 0.0 0.0 0.0 22.3 5.4 0.3 0.2 28.2 1964 1.8 0.0 0.0 19.5 9.5 0.5 0.0 31.3 1965 2.1 0.0 0.0 19.4 7.0 1.0 1.4 30.9 1966 2.2 0.0 0.0 17.6 5.3 2.7 0.7 28.5 1967 5.3 0.0 0.0 15.3 7.7 4.5 2.8 35.6 1968 3.3 0.0 0.0 18.2 6.3 3.9 3.5 35.2 1969 3.9 0.0 0.7 15.6 2.4 4.2 17.6 44.4 1970 4.1 0.0 0.1 15.2 4.5 2.1 2.5 28.5 1971 6.9 0.0 1.0 8.6 2.2 0.4 0.3 19.3 1972 8.8 0.0 0.1 8.5 1.8 0.3 3.0 22.5 1973 4.9 0.2 0.2 7.2 1.5 0.3 0.2 14.5 1974 1.9 0.0 0.0 6.4 8.7 0.0 0.1 17.1 1975 0.6 0.0 0.0 3.2 1.9 0.0 0.0 5.7 1976 0.3 0.0 0.0 1.6 1.6 0.0 0.0 3.4 1977 0.5 0.0 0.0 2.8 1.9 0.0 0.0 5.2 1978 0.8 0.0 0.0 2.3 5.0 0.0 0.0 8.1 1979 0.2 0.0 0.0 5.3 4.4 0.0 0.0 9.9 1980 0.3 0.0 0.0 6.0 1.7 0.0 0.0 8.0 1981 0.7 0.0 0.0 4.7 1.2 0.0 0.0 6.6 1982 0.4 0.0 0.0 10.3 5.0 0.0 0.0 15.8 1983 1.5 0.2 0.0 17.0 3.5 0.0 0.0 22.2 1984 2.2 0.0 0.0 7.9 1.1 0.0 0.0 11.2 1985 0.9 0.0 0.0 2.7 1.2 0.0 0.0 4.8 1986 0.2 0.0 0.0 3.3 1.1 0.0 0.0 4.6 1987 0.2 0.0 0.0 1.6 0.9 0.0 0.0 2.7 1988 0.1 0.0 0.0 0.9 1.8 0.0 0.0 2.8 1989 0.4 0.0 0.0 2.5 5.5 0.0 0.0 8.3 1990 0.2 0.0 0.0 8.0 9.7 0.0 0.0 17.9 1991 0.2 0.0 0.0 3.9 2.3 0.0 0.0 6.4 1992 0.2 0.0 0.0 1.4 1.1 0.0 0.0 2.7 1993 0.2 0.0 0.0 0.5 0.1 0.0 0.0 0.8 1994 0.2 0.1 0.0 0.2 0.1 0.0 0.0 0.6 1995 0.0 0.0 0.0 0.2 0.1 0.0 0.0 0.3 1996 0.2 0.0 0.0 0.3 0.1 0.0 0.0 0.5 1997 0.5 0.0 0.0 0.2 0.0 0.0 0.0 0.8 1998 0.2 0.0 0.0 0.4 0.1 0.0 0.0 0.7 1999 0.5 0.0 0.0 0.7 0.1 0.0 0.0 1.3 2000 0.2 0.0 0.0 0.7 0.0 0.0 0.0 1.0 2001 0.2 0.0 0.0 0.8 0.0 0.0 0.0 1.1 36th SARC Consensus Summary 29
Table A1.3. Commercial samples of southern New England - Mid Atlantic yellowtail flounder by geographic region, half-year and market category (values in italics are Mid Atlantic observer lengths).
Southern New England Mid Atlantic uncl. large small uncl. large small discard year half lengths lengths lengths ages lengths lengths lengths ages lengths 1969 1 5059 0 0 991 950 0 0 143 0 1969 2 5730 0 0 951 1120 0 0 159 0 1970 1 6313 0 0 2515 1238 0 0 377 0 1970 2 9554 0 0 3149 707 0 0 197 0 1971 1 5421 0 0 2165 1212 0 0 387 0 1971 2 3414 0 0 577 1305 0 0 250 0 1972 1 2817 479 741 1483 1132 252 420 442 0 1972 2 1761 364 515 968 395 0 0 99 0 1973 1 1441 675 777 1085 923 0 0 249 0 1973 2 2757 248 362 1035 1293 0 0 299 0 1974 1 2568 112 319 1296 327 251 741 383 0 1974 2 3767 0 299 1396 498 0 0 149 0 1975 1 767 633 1257 1039 220 345 898 456 0 1975 2 321 100 149 189 0 0 0 0 0 1976 1 412 717 843 824 235 157 0 173 0 1976 2 149 190 192 192 426 0 0 161 0 1977 1 0 707 803 572 520 379 340 497 0 1977 2 162 370 275 339 283 0 0 103 0 1978 1 0 747 1222 680 223 85 0 146 0 1978 2 431 433 472 427 322 0 0 104 0 1979 1 249 444 348 379 451 0 0 164 0 1979 2 2050 377 735 1073 164 0 0 54 0 1980 1 1664 1313 1559 1984 214 90 281 228 0 1980 2 916 365 961 803 129 0 0 52 0 1981 1 888 270 151 530 1155 0 0 465 0 1981 2 377 109 1111 554 0 0 0 0 0 1982 1 1071 608 1374 1108 821 0 0 319 0 1982 2 266 401 3361 1210 139 0 188 101 0 1983 1 205 750 2281 1060 578 90 0 197 0 1983 2 252 601 2411 915 0 0 174 50 0 1984 1 416 558 1469 520 1544 0 1244 532 0 1984 2 0 932 2976 832 469 0 161 120 0 1985 1 138 822 2524 833 842 0 260 235 0 1985 2 443 620 2725 759 172 0 154 60 0 1986 1 422 326 1753 537 380 107 410 269 0 1986 2 299 498 1517 472 0 0 0 0 0 1987 1 0 662 964 391 765 0 0 201 0 1987 2 0 586 1042 347 0 0 0 0 0 1988 1 0 800 1272 536 240 0 0 54 0 1988 2 0 381 692 294 0 0 0 0 0 1989 1 0 759 1274 559 0 0 0 0 432 1989 2 0 504 971 351 316 0 0 75 183 1990 1 0 776 1155 504 565 0 0 0 1311 1990 2 0 693 956 389 0 0 0 0 0 1991 1 0 619 932 384 151 0 0 25 273 1991 2 0 671 1034 434 456 0 0 0 209 1992 1 0 524 895 400 376 0 0 50 1 1992 2 0 520 660 326 35 0 0 0 0 1993 1 0 348 625 265 45 0 0 0 7 1993 2 0 72 234 0 7 0 0 0 0 1994 1 0 102 133 58 3 0 0 0 10 1994 2 0 252 254 128 0 94 134 0 7 1995 1 78 234 240 143 17 0 0 0 70 1995 2 0 94 146 50 3 0 0 0 57 1996 1 0 0 0 0 21 0 0 0 255 1996 2 0 469 691 305 28 0 0 60 479 1997 1 215 813 803 468 473 0 0 78 433 1997 2 78 328 679 238 67 91 0 17 253 1998 1 0 283 596 275 27 0 0 0 41 1998 2 0 0 127 37 101 100 0 0 8 1999 1 262 408 333 154 281 77 111 83 61 1999 2 0 0 0 0 0 0 0 0 0 2000 1 114 589 94 170 0 85 0 14 537 2000 2 300 715 598 80 0 0 0 0 26 2001 1 0 263 710 249 0 0 117 48 14 2001 2 222 626 1028 526 0 0 0 114 33 30 36th SAW Consensus Summary
Table A1.4a. Landings at age (thousands) of yellowtail flounder in southern New England.
Age Year 1 2 3 4 5 6 7 8+ Total 1973 28 2570 7169 4630 1716 1517 257 55 17,942 1974 130 1766 3922 5053 2500 950 1021 196 15,538 1975 170 2352 1496 973 1257 549 308 163 7,268 1976 0 1396 898 245 337 391 167 188 3,622 1977 66 2039 3931 392 205 253 123 160 7,169 1978 21 3209 1488 1025 165 34 44 28 6,014 1978 19 4972 8252 1033 428 96 24 0 14,824 1980 119 4557 6324 3619 472 117 19 12 15,239 1981 0 2732 6418 2449 884 128 14 0 12,625 1982 56 17414 12788 1741 404 78 7 0 32,488 1983 57 13823 33242 3347 376 129 35 7 51,016 1984 45 2624 13902 6587 740 244 7 14 24,163 1985 166 3984 1496 1312 774 135 27 4 7,898 1986 39 5926 2882 561 324 119 21 1 9,873 1987 72 1370 2014 803 139 47 8 1 4,454 1988 0 1154 504 407 101 17 6 0 2,189 1989 0 5213 1269 280 41 3 0 0 6,806 1990 0 415 18476 1352 68 5 0 0 20,316 1991 0 253 2230 6606 81 1 17 0 9,188 1992 0 301 896 1687 246 10 3 0 3,143 1993 0 211 361 417 124 4 0 0 1,117 1994 0 15 187 136 120 48 1 0 507 1995 0 154 125 182 18 1 3 0 483 1996 0 224 439 122 15 10 5 1 816 1997 0 33 319 146 14 2 2 1 517 1998 0 300 364 139 25 2 0 0 830 1999 0 9 1231 158 45 11 5 0 1,458 2000 0 420 805 323 12 2 1 1 1,563 2001 0 201 1086 297 83 18 9 0 1,694 36th SARC Consensus Summary 31
Table A1.4b. Landed weight (kg) at age of yellowtail in southern New England.
Age Year 1 2 3 4 5 6 7 8+
1973 0.210 0.298 0.381 0.420 0.430 0.506 0.611 -
1974 0.203 0.308 0.359 0.429 0.477 0.476 0.518 -
1975 0.218 0.290 0.385 0.439 0.436 0.469 0.515 -
1976 - 0.303 0.427 0.528 0.533 0.568 0.603 -
1977 0.215 0.284 0.385 0.521 0.529 0.484 0.612 -
1978 0.234 0.296 0.402 0.543 0.710 0.791 0.677 -
1979 0.189 0.301 0.366 0.476 0.590 0.684 0.679 -
1980 0.206 0.281 0.384 0.499 0.690 0.891 1.182 -
1981 0.140 0.262 0.343 0.484 0.619 0.664 0.476 -
1982 0.226 0.263 0.354 0.502 0.661 0.821 0.956 -
1983 0.175 0.262 0.341 0.499 0.671 0.829 0.838 -
1984 0.182 0.239 0.298 0.388 0.497 0.652 0.724 -
1985 0.183 0.264 0.370 0.428 0.541 0.620 0.867 -
1986 0.186 0.285 0.335 0.470 0.598 0.617 0.804 -
1987 0.247 0.268 0.361 0.412 0.542 0.595 0.905 -
1988 - 0.293 0.398 0.501 0.664 0.936 0.937 -
1989 - 0.337 0.389 0.546 0.736 0.959 1.278 -
1990 - 0.327 0.378 0.461 0.800 0.884 0.781 -
1991 - 0.336 0.379 0.426 0.715 1.530 0.599 -
1992 - 0.347 0.386 0.460 0.631 0.802 1.432 -
1993 - 0.358 0.430 0.471 0.645 1.040 1.040 -
1994 - 0.319 0.349 0.416 0.556 0.717 0.876 -
1995 - 0.317 0.410 0.460 0.668 0.883 0.863 -
1996 - 0.363 0.399 0.476 0.602 0.680 0.780 -
1997 - 0.347 0.435 0.494 0.677 0.847 0.926 -
1998 - 0.284 0.399 0.528 0.694 0.790 0.707 -
1999 - 0.334 0.440 0.574 0.763 1.106 1.104 -
2000 - 0.371 0.477 0.604 0.690 0.979 1.040 -
2001 - 0.393 0.441 0.617 0.743 0.919 0.948 -
32 36th SAW Consensus Summary
Table A1.4c. Landings at age (thousands) of yellowtail in the Mid Atlantic.
Age Year 1 2 3 4 5 6 7 8+ Total 1973 0 80 3426 3297 3510 3788 660 8 14,769 1974 0 87 838 2272 1187 648 453 80 5,565 1975 6 340 387 147 340 243 108 81 1,652 1976 0 78 269 82 112 86 63 1 690 1977 2 221 917 115 73 51 44 18 1,441 1978 0 880 669 445 82 27 26 20 2,149 1979 0 142 296 29 10 5 5 1 488 1980 18 217 253 210 40 12 3 4 757 1981 0 284 841 477 227 33 3 5 1,869 1982 0 566 665 114 11 1 0 0 1,357 1983 0 593 3914 237 9 17 2 2 4,773 1984 2 434 5136 1467 138 1 9 0 7,188 1985 0 1046 659 656 335 69 11 0 2,775 1986 1 289 405 74 32 8 0 0 808 1987 4 33 335 123 28 8 1 0 532 1988 0 59 28 99 33 9 0 0 229 1989 0 705 244 51 1 0 0 0 1,001 1990 0 8 446 184 11 0 0 0 649 1991 0 0 113 208 75 33 0 0 429 1992 0 0 115 393 18 4 1 0 532 1993 0 34 71 285 21 0 0 0 411 1994 0 7 79 103 164 77 3 0 432 1995 0 45 14 7 1 2 1 2 73 1996 0 117 105 92 32 5 0 0 353 1997 0 35 751 378 46 3 1 2 1,217 1998 0 96 133 117 46 7 3 0 401 1999 0 18 835 100 44 0 0 0 998 2000 0 74 252 110 3 1 0 0 440 2001 32 200 111 43 14 10 0 409 36th SARC Consensus Summary 33
Table A1.4d. Landed weight (kg) at age of yellowtail in the Mid Atlantic.
Age Year 1 2 3 4 5 6 7 8+
1973 - 0.184 0.267 0.310 0.358 0.382 0.421 0.830 1974 - 0.210 0.311 0.323 0.358 0.364 0.386 0.450 1975 0.218 0.283 0.342 0.385 0.432 0.430 0.478 0.524 1976 - 0.265 0.342 0.409 0.397 0.429 0.404 0.621 1977 0.201 0.268 0.364 0.447 0.469 0.466 0.511 0.553 1978 - 0.241 0.339 0.520 0.566 0.553 0.568 0.605 1979 - 0.249 0.317 0.424 0.586 0.461 0.344 0.830 1980 0.202 0.269 0.373 0.509 0.581 0.712 0.760 0.696 1981 0.140 0.261 0.337 0.421 0.504 0.687 0.473 0.649 1982 - 0.263 0.325 0.458 0.636 0.863 - -
1983 0.175 0.238 0.315 0.455 0.523 0.707 0.765 0.765 1984 0.144 0.215 0.287 0.387 0.436 0.704 0.614 -
1985 - 0.235 0.355 0.367 0.419 0.494 0.450 -
1986 0.185 0.258 0.305 0.408 0.476 0.563 0.720 -
1987 0.260 0.282 0.303 0.350 0.409 0.536 0.619 -
1988 - 0.303 0.369 0.459 0.449 0.539 - -
1989 - 0.359 0.458 0.606 0.700 0.882 - -
1990 - 0.330 0.351 0.386 0.509 - - -
1991 - 0.234 0.392 0.426 0.680 0.881 - -
1992 - - 0.382 0.459 0.636 0.808 1.048 -
1993 - 0.302 0.431 0.422 0.614 - - -
1994 - 0.323 0.362 0.494 0.602 0.715 0.913 -
1995 - 0.222 0.315 0.350 0.494 0.480 0.594 0.769 1996 - 0.378 0.412 0.471 0.580 0.687 - -
1997 - 0.296 0.416 0.474 0.552 0.952 1.128 1.941 1998 - 0.344 0.457 0.626 0.827 1.007 1.048 -
1999 - 0.360 0.458 0.548 0.563 - - -
2000 - 0.371 0.472 0.616 0.931 1.173 1.040 1.040 2001 - 0.366 0.464 0.643 0.817 0.968 1.030 34 36th SAW Consensus Summary
Table A1.5a. Discard estimates for southern New England yellowtail flounder for 2000 and 2001 from logbook (VTR) data (observer data, OB, also listed for comparison).
2000 logbook data half kept disc landings discards year gear (mt) (mt) d/k (mt) (mt) 1 trawl 69.0 2.1 0.031 343.9 10.5 dredge 0.1 3.3 23.102 0.6 13.6 2 trawl 97.7 2.5 0.026 402.6 10.5 dredge 0.1 3.5 38.696 0.1 2.2 total 36.8 2000 observer data half kept disc discard year gear (mt) (mt) d/k trips lengths 1 trawl 0.20 0.21 1.069 2 90 dredge 0 2 trawl 1.57 0.37 0.237 2 82 dredge 0.04 0.63 17.859 1 22 total 194 2001 logbook data half kept disc landings discards year gear (mt) (mt) d/k (mt) (mt) 1 trawl 162.0 3.9 0.024 602.9 14.5 dredge 0.1 2.2 40.907 0.0 0.4 2 trawl 42.7 1.3 0.029 225.0 6.6 dredge 0.0 2.5 280.478 0.1 20.1 total 41.7 2001 observer data half kept disc discard year gear (mt) (mt) d/k trips lengths 1 trawl 11.15 0.75 0.067 1 72 dredge 0.00 0.28 1 0 2 trawl 1.46 0.21 0.142 3 82 dredge 0 0 total 154 36th SARC Consensus Summary 35
Table A1.5b. Discard estimates for Mid Atlantic yellowtail flounder, 1994-2001 from logbook (VTR) data (observer data, OB, also listed for comparison).
Trawl Discards OB OB OB VTR VTR VTR year half kept discard d/k kept discard d/k landings discards 1994 1 0.054 0.004 0.07 0.292 0.062 0.2127 63.1 13.4 1994 2 0.001 0.024 47.20 0.675 0.043 0.0639 93.3 6.0 1995 1 0.000 0.001 1.436 0.692 0.4817 5.2 2.5 1995 2 2.994 0.170 0.0568 11.1 0.6 1996 1 0.001 0.000 0.00 24.362 1.442 0.0592 83.3 4.9 1996 2 0.000 0.345 22.607 0.815 0.0361 66.0 2.4 1997 1 1.925 0.133 0.07 84.408 3.500 0.0415 451.7 18.7 1997 2 0.000 0.381 9.887 0.714 0.0723 71.3 5.1 1998 1 0.001 0.000 0.00 29.147 2.302 0.0790 117.5 9.3 1998 2 0.018 0.002 0.13 12.033 0.765 0.0636 86.0 5.5 1999 1 0.000 0.009 103.788 4.402 0.0424 409.9 17.4 1999 2 9.022 0.484 0.0536 57.7 3.1 2000 1 0.001 0.030 21.36 46.856 0.968 0.0206 152.8 3.2 2000 2 6.269 0.424 0.07 14.233 0.467 0.0328 65.3 2.1 2001 1 0.079 0.000 0.00 38.375 0.956 0.0249 206.5 5.1 2001 2 0.000 0.003 4.040 0.175 0.0433 27.7 1.2 Dredge Discards 1994 1 0.045 0.037 0.82 0.320 0.445 1.392 69.1 96.2 1994 2 0.001 0.006 4.57 0.091 0.068 0.747 12.6 9.4 1995 1 0.030 0.245 8.24 0.889 0.494 0.556 3.2 1.8 1995 2 0.014 0.361 25.62 0.439 0.426 0.971 1.6 1.6 1996 1 0.081 0.856 10.54 0.859 0.370 0.430 2.9 1.3 1996 2 0.054 0.674 12.57 0.529 1.150 2.174 1.5 3.4 1997 1 0.211 0.863 4.10 1.179 0.628 0.533 6.3 3.4 1997 2 0.095 0.200 2.11 0.894 0.284 0.317 6.4 2.0 1998 1 0.023 0.103 4.48 1.410 1.281 0.909 5.7 5.2 1998 2 0.000 0.058 144.50 0.839 0.578 0.689 6.0 4.1 1999 1 0.015 0.126 8.37 1.126 0.166 0.147 35.1 5.2 1999 2 0.052 0.009 0.175 0.0 0.0 2000 1 0.000 0.211 0.122 0.227 1.859 2.0 3.8 2000 2 0.000 0.033 0.077 0.261 3.387 0.1 0.4 2001 all 0.079 0.000 0.00 0.062 1.699 27.398 0.9 24.6 36 36th SAW Consensus Summary
Table A1.6a. Discards at age (thousands) of yellowtail flounder in southern New England.
Age Year 1 2 3 4 5 6 7 1973 160 2486 1130 43 0 0 0 1974 728 26568 793 45 0 0 0 1975 8670 1427 1 10 0 0 0 1976 214 5203 14 0 0 0 0 1977 5376 2732 42 0 0 0 0 1978 8677 10102 7 0 0 0 0 1979 185 14253 119 0 0 0 0 1980 869 5441 18 0 0 0 0 1981 38 4013 319 0 0 0 0 1982 113 17716 905 3 0 0 0 1983 2469 4607 5373 17 0 0 0 1984 465 3107 941 74 0 0 0 1985 2064 3031 20 0 0 0 0 1986 423 3754 39 0 0 0 0 1987 1518 2034 19 0 0 0 0 1988 5899 896 4 0 0 0 0 1989 24 14002 1834 131 6 0 0 1990 192 1633 23709 673 11 0 0 1991 445 1354 2820 2883 12 0 0 1992 477 1152 1086 659 33 0 0 1993 13 212 15 9 0 0 0 1994 9 134 35 29 12 2 0 1995 7 94 38 27 12 3 0 1996 21 81 56 29 13 2 0 1997 1 23 32 4 1 0 0 1998 0 88 114 40 9 3 1 1999 3 64 215 22 11 2 0 2000 31 35 29 13 0 0 0 2001 1 35 75 3 2 0 0 36th SARC Consensus Summary 37
Table A1.6b. Discarded weight at age of southern New England yellowtail flounder.
Age Year 1 2 3 4 5 6 7 1973 0.210 0.298 0.381 0.420 1974 0.203 0.308 0.359 0.429 1975 0.218 0.290 0.385 0.439 1976 0.228 0.303 0.427 1977 0.215 0.284 0.385 1978 0.234 0.296 0.402 1979 0.189 0.301 0.366 1980 0.206 0.281 0.384 1981 0.140 0.262 0.343 1982 0.226 0.263 0.354 0.502 1983 0.175 0.262 0.341 0.499 1984 0.182 0.239 0.298 0.388 1985 0.183 0.264 0.370 1986 0.186 0.285 0.335 1987 0.247 0.268 0.361 1988 0.270 0.293 0.398 1989 0.311 0.337 0.389 0.546 0.736 1990 0.301 0.327 0.378 0.461 0.800 1991 0.206 0.248 0.302 0.387 0.413 1992 0.167 0.308 0.351 0.354 0.344 1993 0.122 0.358 0.430 0.471 1994 0.108 0.323 0.349 0.416 0.556 0.358 1995 0.123 0.317 0.410 0.477 0.668 0.883 1996 0.147 0.404 0.495 0.424 0.610 0.922 1997 0.143 0.220 0.325 0.532 0.722 1998 0.020 0.284 0.399 0.528 0.694 0.790 0.707 1999 0.208 0.272 0.389 0.565 0.767 0.586 1.183 2000 0.020 0.314 0.473 0.572 2001 0.153 0.327 0.363 0.568 0.528 38 36th SAW Consensus Summary
Table A1.6c. Discards at age (thousands) of Mid Atlantic yellowtail flounder.
Age Year 1 2 3 4 5 6 1973 32 496 225 9 0 0 1974 3 98 3 0 0 0 1975 64 11 0 0 0 0 1976 0 0 0 0 0 0 1977 69 35 1 0 0 0 1978 0 0 0 0 0 0 1979 1 52 0 0 0 0 1980 0 0 0 0 0 0 1981 0 0 0 0 0 0 1982 0 0 0 0 0 0 1983 142 265 309 1 0 0 1984 5 34 10 1 0 0 1985 9 13 0 0 0 0 1986 0 1 0 0 0 0 1987 0 0 0 0 0 0 1988 0 0 0 0 0 0 1989 0 0 0 0 0 0 1990 0 1 12 0 0 0 1991 1 3 6 6 0 0 1992 0 0 0 0 0 0 1993 0 0 0 0 0 0 1994 145 592 11 13 13 0 1995 0 15 3 3 0 1 1996 1 5 26 5 0 0 1997 1 11 64 10 0 0 1998 3 27 24 10 1 2 1999 3 15 39 8 3 0 2000 4 38 5 2 0 0 2001 0 7 51 13 2 0 36th SARC Consensus Summary 39
Table A1.6d. Discarded weight at age of Mid Atlantic yellowtail flounder.
Age Year 1 2 3 4 5 6 1973 0.210 0.298 0.381 0.420 1974 0.203 0.308 0.359 0.429 1975 0.218 0.290 0.385 0.439 1976 0.228 0.303 0.427 1977 0.215 0.284 0.385 1978 0.234 0.296 0.402 1979 0.189 0.301 0.366 1980 0.206 0.281 0.384 1981 0.140 0.262 0.343 1982 0.226 0.263 0.354 0.502 1983 0.175 0.262 0.341 0.499 1984 0.182 0.239 0.298 0.388 1985 0.183 0.264 0.370 1986 0.186 0.285 0.335 1987 0.247 0.268 0.361 1988 0.270 0.293 0.398 1989 0.311 0.337 0.389 0.546 0.736 1990 0.301 0.327 0.378 0.461 0.800 1991 0.206 0.248 0.302 0.387 0.413 1992 0.167 0.308 0.351 0.354 0.344 1993 0.122 0.358 0.430 0.471 1994 0.065 0.171 0.348 0.407 0.377 1995 0.146 0.233 0.318 0.385 0.506 0.507 1996 0.163 0.220 0.347 0.358 0.652 0.810 1997 0.133 0.230 0.347 0.399 0.567 0.876 1998 0.162 0.267 0.389 0.507 0.627 0.499 1999 0.234 0.251 0.399 0.501 0.608 0.899 2000 0.149 0.137 0.447 0.570 0.765 2001 0.153 0.278 0.385 0.590 0.621 0.765 40 36th SAW Consensus Summary
Table A1.7. NEFSC Survey indices of abundance and biomass of southern New England
- Mid Atlantic yellowtail flounder.
Fall Survey year age-0 age-1 age-2 age-3 age-4 age-5 age-6 age-7 age-8 age-9 sum kg/tow 1963 0.030 14.778 12.274 9.972 4.944 0.683 0.059 0.082 0.000 0.000 42.822 14.023 1964 0.000 13.900 19.067 3.381 5.356 2.643 0.543 0.036 0.000 0.000 44.925 13.972 1965 0.166 22.272 12.835 4.327 1.489 1.184 0.146 0.000 0.000 0.000 42.418 10.228 1966 0.569 34.899 10.656 2.342 0.902 0.175 0.000 0.000 0.000 0.000 49.542 9.033 1967 0.177 23.579 29.045 12.719 1.212 0.260 0.047 0.124 0.000 0.000 67.164 14.018 1968 0.000 13.882 21.622 24.639 1.571 0.263 0.325 0.069 0.000 0.000 62.370 13.038 1969 0.056 10.440 11.316 33.936 4.454 0.049 0.019 0.019 0.000 0.000 60.288 14.472 1970 0.067 4.414 8.047 29.866 18.927 3.305 0.359 0.047 0.000 0.000 65.032 16.211 1971 0.000 14.540 12.485 6.886 12.452 1.909 0.162 0.123 0.000 0.000 48.556 8.975 1972 0.000 3.245 32.938 33.089 33.080 18.618 2.305 0.101 0.000 0.000 123.376 31.543 1973 0.000 1.779 1.747 4.086 2.318 1.564 0.768 0.162 0.000 0.000 12.422 3.125 1974 0.132 0.695 1.185 0.433 1.640 0.687 0.297 0.146 0.014 0.042 5.271 1.545 1975 0.000 1.533 0.416 0.136 0.217 0.213 0.048 0.070 0.000 0.000 2.634 0.602 1976 0.000 1.964 4.204 0.350 0.046 0.073 0.190 0.220 0.099 0.000 7.147 1.954 1977 0.028 2.289 1.439 0.519 0.044 0.040 0.035 0.065 0.000 0.000 4.459 1.125 1978 0.000 2.080 4.771 0.296 0.236 0.024 0.006 0.048 0.000 0.021 7.481 2.004 1979 0.000 1.493 3.283 1.579 0.241 0.026 0.026 0.000 0.000 0.000 6.646 1.818 1980 0.000 1.153 2.908 0.757 0.313 0.000 0.000 0.000 0.000 0.000 5.130 1.354 1981 0.000 9.511 9.498 1.251 0.198 0.103 0.037 0.000 0.000 0.000 20.597 4.046 1982 0.000 2.040 17.794 4.392 0.535 0.215 0.000 0.000 0.000 0.000 24.976 5.706 1983 0.000 1.920 11.278 5.593 0.458 0.038 0.000 0.026 0.000 0.000 19.314 4.490 1984 0.000 1.444 1.275 1.529 0.334 0.000 0.000 0.000 0.000 0.000 4.582 1.033 1985 0.000 0.869 0.375 0.134 0.080 0.000 0.000 0.000 0.000 0.000 1.458 0.298 1986 0.000 0.606 1.826 0.523 0.123 0.025 0.000 0.000 0.000 0.000 3.104 0.754 1987 0.073 1.067 0.451 0.359 0.030 0.024 0.000 0.024 0.000 0.000 2.028 0.401 1988 0.000 4.370 0.310 0.141 0.156 0.021 0.034 0.000 0.000 0.000 5.032 0.510 1989 0.000 0.198 10.492 1.370 0.072 0.000 0.000 0.000 0.000 0.000 12.132 2.359 1990 0.000 0.539 1.847 3.117 0.194 0.000 0.000 0.000 0.000 0.000 5.696 1.305 1991 0.000 0.588 0.243 1.516 0.367 0.000 0.000 0.000 0.000 0.000 2.713 0.755 1992 0.000 0.168 0.024 0.072 0.285 0.000 0.000 0.000 0.000 0.000 0.548 0.147 1993 0.000 0.332 0.028 0.130 0.104 0.000 0.000 0.000 0.000 0.000 0.594 0.116 1994 0.000 0.732 0.448 0.107 0.129 0.066 0.025 0.000 0.000 0.000 1.507 0.308 1995 0.000 0.139 0.645 0.257 0.115 0.000 0.000 0.025 0.028 0.000 1.209 0.304 1996 0.000 0.448 0.161 0.320 0.000 0.000 0.000 0.000 0.000 0.000 0.929 0.208 1997 0.000 0.822 0.519 1.459 0.271 0.024 0.000 0.000 0.000 0.000 3.095 0.851 1998 0.023 0.890 1.620 0.124 0.049 0.000 0.023 0.000 0.000 0.000 2.728 0.655 1999 0.000 1.238 0.392 0.279 0.028 0.028 0.000 0.000 0.000 0.000 1.964 0.468 2000 0.000 0.049 1.669 0.303 0.171 0.000 0.000 0.023 0.000 0.000 2.215 0.718 2001 0.000 0.390 0.611 0.158 0.071 0.000 0.000 0.000 0.000 0.000 1.231 0.419 36th SARC Consensus Summary 41
Table A1.7 cont.
Spring Survey year age-1 age-2 age-3 age-4 age-5 age-6 age-7 age-8 age-9 age-10 age-11 sum kg/tow 1968 1.014 29.910 38.854 13.103 1.076 0.040 0.184 0.000 0.000 0.000 0.000 84.181 18.645 1969 2.941 18.796 29.464 14.069 1.599 0.147 0.048 0.000 0.000 0.000 0.000 67.064 14.311 1970 1.045 7.311 18.942 16.237 3.518 0.656 0.123 0.005 0.022 0.000 0.000 47.860 12.066 1971 0.447 7.616 8.124 20.765 3.713 0.371 0.004 0.000 0.000 0.004 0.000 41.043 9.552 1972 0.196 12.355 11.201 5.986 9.887 2.394 0.303 0.000 0.000 0.000 0.000 42.321 10.815 1973 0.838 5.467 14.753 8.335 6.432 7.987 0.852 0.230 0.083 0.000 0.000 44.977 12.115 1974 0.511 2.188 2.607 5.016 2.891 1.154 1.291 0.145 0.027 0.000 0.000 15.830 4.918 1975 0.358 1.171 0.406 0.665 0.709 0.531 0.156 0.197 0.000 0.000 0.000 4.193 1.307 1976 0.016 4.182 0.536 0.256 0.245 0.338 0.096 0.031 0.000 0.000 0.000 5.699 1.666 1977 1.618 1.557 2.758 0.242 0.154 0.189 0.093 0.080 0.006 0.046 0.000 6.743 1.963 1978 2.681 10.302 1.791 0.778 0.253 0.126 0.123 0.158 0.010 0.000 0.000 16.221 3.513 1979 1.002 2.967 1.601 0.255 0.124 0.018 0.018 0.014 0.000 0.000 0.012 6.009 1.318 1980 0.683 6.353 4.298 2.684 0.261 0.070 0.005 0.009 0.015 0.001 0.005 14.384 4.830 1981 0.810 18.598 4.817 2.502 0.580 0.113 0.000 0.000 0.000 0.000 0.000 27.420 6.930 1982 0.149 17.329 5.610 1.406 0.467 0.135 0.017 0.000 0.000 0.000 0.000 25.114 5.865 1983 0.016 5.329 8.803 0.598 0.191 0.000 0.000 0.000 0.000 0.000 0.000 14.938 4.097 1984 0.038 0.453 0.902 2.110 0.354 0.262 0.000 0.000 0.000 0.000 0.000 4.119 1.302 1985 0.267 1.613 0.406 0.480 0.714 0.135 0.019 0.000 0.000 0.000 0.000 3.634 0.948 1986 0.016 2.893 0.916 0.237 0.124 0.016 0.000 0.000 0.000 0.000 0.000 4.201 1.052 1987 0.000 0.086 0.701 0.167 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.954 0.319 1988 0.285 0.357 0.125 0.174 0.294 0.029 0.000 0.000 0.000 0.000 0.000 1.263 0.378 1989 0.162 11.211 0.537 0.113 0.000 0.000 0.000 0.000 0.000 0.000 0.000 12.022 2.090 1990 0.090 0.485 15.349 2.194 0.079 0.000 0.000 0.000 0.000 0.000 0.000 18.197 5.064 1991 0.228 0.611 2.509 4.156 0.539 0.060 0.000 0.000 0.000 0.000 0.000 8.103 2.508 1992 0.036 0.051 0.571 1.597 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.255 0.794 1993 0.016 0.253 0.112 0.441 0.071 0.000 0.000 0.000 0.000 0.000 0.000 0.894 0.341 1994 0.016 0.269 0.016 0.000 0.068 0.019 0.000 0.000 0.000 0.000 0.000 0.389 0.136 1995 0.016 1.169 0.068 0.092 0.019 0.037 0.000 0.016 0.016 0.000 0.000 1.433 0.329 1996 0.000 0.398 1.303 0.566 0.072 0.000 0.000 0.000 0.000 0.000 0.000 2.339 0.747 1997 0.053 0.885 1.144 0.327 0.067 0.000 0.000 0.000 0.000 0.000 0.000 2.475 0.789 1998 0.068 3.016 0.386 0.161 0.036 0.021 0.000 0.000 0.000 0.000 0.000 3.688 0.848 1999 0.036 0.651 1.930 0.349 0.074 0.000 0.023 0.000 0.000 0.000 0.000 3.062 1.138 2000 0.019 1.245 1.006 0.559 0.043 0.000 0.000 0.000 0.000 0.000 0.000 2.873 0.990 2001 0.000 0.069 1.158 0.240 0.082 0.023 0.000 0.000 0.000 0.000 0.000 1.572 0.657 2002 0.049 1.191 0.235 0.200 0.067 0.000 0.000 0.000 0.000 0.000 0.000 1.742 0.510 42 36th SAW Consensus Summary
Table A1.7 continued.
Winter Survey year age-1 age-2 age-3 age-4 age-5 age-6 age-7 age-8 sum kg/tow 1992 0.011 1.619 3.477 8.063 0.959 0.000 0.000 0.000 14.129 5.264 1993 0.596 1.924 1.057 2.487 0.292 0.000 0.000 0.000 6.357 2.118 1994 0.366 8.654 0.742 1.654 0.966 0.353 0.118 0.000 12.854 3.924 1995 0.090 10.681 2.698 0.597 0.253 0.185 0.016 0.000 14.519 3.464 1996 0.041 1.285 8.235 0.851 0.140 0.065 0.015 0.015 10.648 3.346 1997 0.156 2.380 9.785 2.958 0.529 0.000 0.038 0.000 15.846 5.720 1998 0.118 7.841 1.596 1.158 0.112 0.000 0.018 0.000 10.843 2.780 1999 0.243 2.909 10.176 0.777 0.311 0.056 0.023 0.000 14.494 5.226 2000 0.109 4.917 3.006 1.160 0.073 0.100 0.000 0.000 9.364 3.025 2001 0.028 0.895 8.542 1.615 0.254 0.096 0.046 0.000 11.475 4.786 2002 0.012 2.735 2.578 2.047 0.100 0.020 0.000 0.000 7.492 2.589 Scallop Survey year all age-1 1982 3.123 0.362 1983 0.858 0.255 1984 0.309 0.180 1985 0.577 0.465 1986 0.199 0.015 1987 0.150 0.054 1988 7.482 7.359 1989 3.774 0.579 1990 0.370 0.158 1991 0.230 0.151 1992 0.169 0.108 1993 0.192 0.170 1994 0.732 0.573 1995 0.507 0.072 1996 38.479 0.120 1997 0.886 0.736 1998 0.567 0.253 1999 0.456 0.357 2000 0.432 0.082 2001 0.106 0.063 2002 0.152 0.020 36th SARC Consensus Summary 43
Table A1.8. Correlation among abundance indices by age.
Age 1 Fall Spring Winter Scallop Fall 1.00 Spring 0.45 1.00 Winter 0.25 0.00 1.00 Scallop 0.49 0.40 0.47 1.00 Age 2 Fall Spring Winter Fall 1.00 Spring 0.82 1.00 Winter 0.45 0.65 1.00 Age 3 Fall Spring Winter Fall 1.00 Spring 0.71 1.00 Winter 0.45 0.86 1.00 Age 4 Fall Spring Winter Fall 1.00 Spring 0.74 1.00 Winter 0.46 0.57 1.00 Age 5 Fall Spring Winter Fall 1.00 Spring 0.36 1.00 Winter -0.46 0.54 1.00 Age 6 Fall Spring Winter Fall 1.00 Spring 0.57 1.00 Winter -0.49 -0.55 1.00 Age 7+ Fall Spring Winter Fall 1.00 Spring -0.18 1.00 Winter -0.07 -0.31 1.00 44 36th SAW Consensus Summary
Table A1.9c. Results of virtual population analysis of southern New England - Mid Atlantic yellowtail flounder.
Abundance (thousands) age-1 age-2 age-3 age-4 age-5 age-6 age-7+ sum 1973 43532 17681 27907 16078 8927 11005 2006 127136 1974 10627 35442 9380 12035 5945 2580 2769 78778 1975 31562 7921 3212 2653 3185 1531 1256 51320 1976 14634 17779 2749 925 1149 1162 1009 39407 1977 50316 11788 8514 1182 462 535 596 73393 1978 54165 36207 5103 2545 509 126 243 98898 1979 32034 36476 16803 2220 754 193 57 88537 1980 44493 26042 12293 5915 856 221 64 89884 1981 138470 35518 12078 4097 1378 238 32 191811 1982 64223 113335 22719 3032 707 123 11 204150 1983 16726 52429 60492 5609 801 203 62 136322 1984 19164 11280 25473 10766 1334 308 36 68361 1985 20993 15223 3625 2767 1459 298 60 44425 1986 7315 15161 5158 1000 485 191 32 29342 1987 15044 5570 3392 1213 244 75 13 25551 1988 124008 10875 1450 634 155 49 11 137182 1989 17769 96192 6995 702 61 6 0 121725 1990 8083 14526 60731 2699 157 7 0 86203 1991 3934 6444 10032 11136 211 47 23 31827 1992 2267 2817 3819 3537 338 21 6 12805 1993 2041 1425 992 1229 417 8 0 6112 1994 2953 1660 753 407 363 210 7 6353 1995 3392 2278 682 334 79 18 20 6803 1996 1988 2771 1586 395 75 37 13 6865 1997 5951 1608 1882 732 98 8 9 10288 1998 3377 4871 1223 486 113 25 7 10102 1999 5753 2762 3525 427 121 19 7 12614 2000 1889 4705 2166 786 89 6 4 9645 2001 3060 1515 3339 786 239 59 35 9033 2002 --- 2504 991 1455 260 79 31 ---
average 25854 19827 10635 3259 1032 646 281 62582 36th SARC Consensus Summary 45
Table A1.9b.
Fishing Mortality age-1 age-2 age-3 age-4 age-5 age-6 age-7+ ages 4-6 1973 0.01 0.43 0.64 0.79 1.04 0.76 0.76 0.86 1974 0.09 2.20 1.06 1.13 1.16 1.15 1.15 1.15 1975 0.37 0.86 1.04 0.64 0.81 0.85 0.85 0.77 1976 0.02 0.54 0.64 0.50 0.57 0.60 0.60 0.56 1977 0.13 0.64 1.01 0.64 1.10 0.99 0.99 0.91 1978 0.20 0.57 0.63 1.02 0.77 0.76 0.76 0.85 1979 0.01 0.89 0.84 0.75 1.03 0.86 0.86 0.88 1980 0.03 0.57 0.90 1.26 1.08 1.04 1.04 1.13 1981 0.00 0.25 1.18 1.56 2.22 1.38 1.38 1.72 1982 0.00 0.43 1.20 1.13 1.05 1.24 1.24 1.14 1983 0.19 0.52 1.53 1.24 0.76 1.58 1.58 1.19 1984 0.03 0.94 2.02 1.80 1.30 2.12 2.12 1.74 1985 0.13 0.88 1.09 1.54 1.83 1.41 1.41 1.59 1986 0.07 1.30 1.25 1.21 1.67 1.33 1.33 1.40 1987 0.12 1.15 1.48 1.86 1.41 1.66 1.66 1.64 1988 0.05 0.24 0.53 2.13 3.06 0.89 0.89 2.03 1989 0.00 0.26 0.75 1.30 1.99 0.82 0.82 1.37 1990 0.03 0.17 1.50 2.35 1.00 1.62 1.62 1.66 1991 0.13 0.32 0.84 3.29 2.13 1.60 1.60 2.34 1992 0.26 0.84 0.93 1.94 3.55 1.40 1.40 2.30 1993 0.01 0.44 0.69 1.02 0.48 0.81 0.81 0.77 1994 0.06 0.69 0.61 1.44 2.82 1.10 1.10 1.79 1995 0.00 0.16 0.34 1.29 0.57 0.58 0.58 0.81 1996 0.01 0.19 0.57 1.19 2.11 0.71 0.71 1.34 1997 0.00 0.07 1.15 1.67 1.19 1.33 1.33 1.40 1998 0.00 0.12 0.85 1.19 1.58 1.00 1.00 1.26 1999 0.00 0.04 1.30 1.37 2.84 1.40 1.40 1.87 2000 0.02 0.14 0.81 0.99 0.21 0.85 0.85 0.68 2001 0.00 0.22 0.63 0.91 0.91 0.91 0.91 0.91 average 0.07 0.55 0.97 1.35 1.46 1.13 1.13 1.31 46 36th SAW Consensus Summary
Table A1.9c.
Spawning Biomass (mt) age-1 age-2 age-3 age-4 age-5 age-6 age-7+ sum 1973 1091 2974 6704 3983 2033 3082 652 20519 1974 248 2970 1912 2739 1483 633 758 10743 1975 704 1090 705 809 910 452 414 5084 1976 396 2933 773 345 417 451 414 5729 1977 1226 1742 1922 420 138 157 216 5821 1978 1397 5701 1354 822 225 58 104 9661 1979 722 5164 3879 709 267 84 23 10848 1980 1085 3932 2927 1612 342 115 42 10055 1981 2318 5716 2276 934 300 82 8 11634 1982 1734 16980 4388 869 278 56 6 24311 1983 323 7496 9789 1529 359 79 25 19600 1984 412 1233 2920 1816 348 76 5 6810 1985 436 1866 758 547 315 88 21 4031 1986 158 1707 915 257 131 62 13 3243 1987 422 630 583 208 65 20 5 1933 1988 3916 1962 416 118 24 25 7 6468 1989 661 19864 1816 208 18 4 0 22571 1990 288 3013 11096 424 73 3 0 14897 1991 92 1005 2146 1075 54 20 6 4398 1992 41 426 859 630 43 8 4 2011 1993 30 286 288 333 201 5 0 1143 1994 23 172 185 91 59 87 3 620 1995 50 433 214 82 38 9 10 836 1996 35 651 460 103 17 18 7 1291 1997 100 306 435 161 32 4 6 1044 1998 65 926 318 154 41 13 4 1521 1999 152 536 815 125 23 10 4 1665 2000 8 1062 661 290 57 4 3 2085 2001 56 355 1014 308 115 35 22 1905 average 627 3211 2156 748 290 198 96 7327 36th SARC Consensus Summary 47
Table A1.10. Yield and spawning biomass per recruit of southern New England - Mid Atlantic yellowtail flounder.
The NEFC Yield and Stock Size per Recruit Program - PDBYPRC PC Ver.1.2 [Method of Thompson and Bell (1934)] 1-Jan-1992 Run Date: 17- 9-2002; Time: 09:41:39.27 SNE-MA YELLOWTAIL FLOUNDER - 1994-2001 INPUT Proportion of F before spawning: .4167 Proportion of M before spawning: .4167 Natural Mortality is Constant at: .200 Initial age is: 1; Last age is: 8 Last age is a PLUS group; Original age-specific PRs, Mats, and Mean Wts from file:
==> snemayt.dat Age-specific Input data for Yield per Recruit Analysis Age l Fish Mort Nat Mort l Proportion l Average Weights l Pattern Pattern l Mature l Catch Stock 1 l .0100 1.0000 l .1300 l .131 .131 2 l .1700 1.0000 l .7400 l .310 .310 3 l .6400 1.0000 l .9800 l .418 .418 4 l 1.0000 1.0000 l 1.0000 l .525 .525 5 l 1.0000 1.0000 l 1.0000 l .671 .671 6 l 1.0000 1.0000 l 1.0000 l .869 .869 7 l 1.0000 1.0000 l 1.0000 l .940 .940 8+ l 1.0000 1.0000 l 1.0000 l 1.026 1.026 Summary of Yield per Recruit Analysis for:
SNE-MA YELLOWTAIL FLOUNDER - 1994-2001 INPUT Slope of the Yield/Recruit Curve at F=0.00: --> 2.5485 F level at slope=1/10 of the above slope (F0.1): -----> .246 Yield/Recruit corresponding to F0.1: -----> .2265 F level to produce Maximum Yield/Recruit (Fmax): -----> .739 Yield/Recruit corresponding to Fmax: -----> .2581 F level at 40 % of Max Spawning Potential (F40): -----> .261 SSB/Recruit corresponding to F40: --------> 1.1288 48 36th SAW Consensus Summary
Table A1.10 continued.
Listing of Yield per Recruit Results for:
SNE-MA YELLOWTAIL FLOUNDER - 1994-2001 INPUT FMORT TOTCTHN TOTCTHW TOTSTKN TOTSTKW SPNSTKN SPNSTKW % MSP
.000 .00000 .00000 5.5167 3.2532 4.0669 2.8223 100.00
.100 .21897 .15373 4.4270 2.2137 2.9720 1.8000 63.78
.200 .33004 .21222 3.8766 1.7151 2.4167 1.3144 46.57 F0.1 .246 .36506 .22653 3.7037 1.5648 2.2416 1.1691 41.42 F40% .261 .37497 .23015 3.6548 1.5231 2.1921 1.1288 40.00
.300 .39788 .23774 3.5420 1.4281 2.0776 1.0374 36.76
.400 .44405 .24951 3.3154 1.2441 1.8470 .8612 30.51
.500 .47780 .25494 3.1508 1.1173 1.6786 .7405 26.24
.600 .50373 .25727 3.0249 1.0251 1.5492 .6531 23.14
.700 .52444 .25804 2.9249 .9552 1.4461 .5872 20.80 Fmax .739 .53153 .25809 2.8908 .9321 1.4108 .5654 20.03
.800 .54146 .25801 2.8432 .9005 1.3615 .5357 18.98
.900 .55578 .25759 2.7747 .8565 1.2904 .4943 17.51 1.000 .56805 .25698 2.7164 .8203 1.2297 .4603 16.31 1.100 .57874 .25630 2.6658 .7899 1.1769 .4318 15.30 1.200 .58817 .25559 2.6214 .7640 1.1304 .4075 14.44 1.300 .59657 .25490 2.5819 .7416 1.0891 .3865 13.69 1.400 .60414 .25424 2.5465 .7219 1.0521 .3682 13.04 1.500 .61100 .25361 2.5145 .7046 1.0185 .3519 12.47 1.600 .61728 .25301 2.4854 .6891 .9880 .3374 11.96 1.700 .62305 .25245 2.4586 .6752 .9600 .3244 11.49 1.800 .62838 .25191 2.4340 .6625 .9342 .3126 11.08 1.900 .63334 .25140 2.4112 .6510 .9103 .3018 10.69 2.000 .63796 .25091 2.3899 .6404 .8880 .2920 10.34 36th SARC Consensus Summary 49
Figure A1.1. Statistical areas for southern New England - Mid Atlantic yellowtail flounder.
50 36th SAW Consensus Summary
Figure A1.2. Catch of southern New England- Mid Atlantic yellowtail flounder.
50 45 SNE foreign SNE Industrial 40 SNE discards SNE landings 35 MA foreign MA discards 30 MA landings Catch (kt) 25 20 15 10 5
0 35 39 43 47 51 55 59 63 67 71 75 79 83 87 91 95 99 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 36th SARC Consensus Summary 51
Figure A1.3. Total catch at age of southern New England - Mid Atlantic yellowtail flounder (size of circle indicates relative magnitude).
-1970
-1972
-1974
-1976
-1978
-1980
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002 0 1 2 3 4 5 6 7 8 Age 52 36th SAW Consensus Summary
Figure A1.4. Mean weight at age of yellowtail flounder in the catch.
1.2 1.0 Age-6 0.8 Age-5 Mean Weight (kg)
Age-4 0.6 Age-3 0.4 Age-2 0.2 Age-1 0.0 73 75 77 79 81 83 85 87 89 91 93 95 97 99 01 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 36th SARC Consensus Summary 53
Figure A1.5. Survey strata for southern New England - Mid Atlantic yellowtail flounder.
54 36th SAW Consensus Summary
Biom ass Index (kg/tow ) Biom ass Index (kg/tow ) Biom ass Index (kg/tow )
19 0 1 2 3 4 5 6 7 8 63 19 63 0 5 10 15 20 25 19 63 0 5 10 15 20 25 30 35 19 19 19 65 65 65 19 19 19 67 67 67 19 19 19 69 69 69 19 19 71 -2SE +2SE mean 71 19 71 19 19 19 73 73 73 19 19 75 75 19 75 36th SARC Consensus Summary 19 19 77 77 19 77 Figure A1.6. Survey indices of southern New England - Mid Atlantic yellowtail 19 19 79 79 19 79 19 19 81 81 19 81 19 19 83 83 19 Fall Survey 83 Winter Survey Spring Survey 19 19 85 85 19 85 19 19 87 87 19 87 19 19 89 89 19 89 19 19 91 91 19 91 19 19 93 93 19 93 19 19 95 95 19 95 19 19 97 97 19 97 19 19 99 99 19 flounder biomass.
20 99 20 01 01 -2SE +2SE mean 20 -2SE +2SE mean 01 55
Figure A1.7a. Distribution of yellowtail flounder in recent NEFSC surveys.
2001 56 36th SAW Consensus Summary
Figure A1.7b.
36th SARC Consensus Summary 57
Figure A1.7c.
58 36th SAW Consensus Summary
Figure A1.8. Area-swept biomass of southern New England - Mid Atlantic yellowtail flounder, by geographic region.
5000 4500 4000 Mid-Atlantic 3500 Southern New England Survey Biomass 3000 2500 2000 1500 1000 500 0
8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 0 36th SARC Consensus Summary 59
Figure A1.9a. Age distribution of southern New England - Mid Atlantic yellowtail flounder from NEFSC surveys (circle size indicates relative abundance).
Fall Survey
-1960 0 1 2 3 4 5 6 7 8 9
-1965
-1970
-1975
-1980
-1985
-1990
-1995
-2000
-2005 Age 60 36th SAW Consensus Summary
Figure A1.9b.
Spring Survey
-1960
-1965
-1970
-1975
-1980
-1985
-1990
-1995
-2000
-2005 0 1 2 3 4 5 6 7 8 9 Age 36th SARC Consensus Summary 61
Figure A1.9c.
Winter Survey
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004 0 1 2 3 4 5 6 7 8 9 Age 62 36th SAW Consensus Summary
Figure A1.10a. Normalized indices of abundance of southern New England - Mid Atlantic yellowtail flounder, by age.
A ge-1 A ge-2 Fall Spring Winter Sc allop Fall Spring Winter 3 3 2
2 1
1 0
0 -1 Z Z
-1 -2
-3
-2
-4
-3
-5
-4 -6 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 A ge-3 A ge-4 Fall Spring Winter Fall Spring Winter 3 3 2
2 1
0 1
-1 Z Z 0
-2
-3 -1
-4
-2
-5
-6 -3 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 36th SARC Consensus Summary 63
Figure A1.10b.
A ge-5 A ge-6 Fall Spring Winter Fall Spring 3 3 2 2 1 1 0 0 Z Z
-1 -1
-2 -2
-3 -3
-4 -4 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 A ge-7+
Fall Spring 2
1.5 1
0.5 0
-0.5 Z
-1
-1.5
-2
-2.5
-3
-3.5 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 64 36th SAW Consensus Summary
Figure A1.11a. Calibration residuals from southern New England - Mid Atlantic yellowtail flounder ADAPT analysis.
A ge-1 A ge-2 Fall Spring Winter Sc allop Fall Spring Winter 6 6 4 4 2
2 0
E 0 E
-2
-2
-4
-4
-6
-6 -8 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 A ge-3 A ge-4 Fall Spring Winter Fall Spring Winter 6 4 5
3 4
3 2 2
1 E 1 E 0
0
-1
-1
-2
-2
-3
-4 -3 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 36th SARC Consensus Summary 65
Figure A1.11b.
A ge-5 A ge-6 Fall Spring Winter Fall Spring 4 4 3 3 2 2 1 1 E E 0 0
-1 -1
-2 -2
-3 -3 73 76 79 82 85 88 91 94 97 00 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 19 20 A ge-7+
Fall Spring 4
3 2
1 E 0
-1
-2
-3
-4 73 76 79 82 85 88 91 94 97 00 19 19 19 19 19 19 19 19 19 20 66 36th SAW Consensus Summary
Figure A1.12a. VPA results for southern New England - Mid Atlantic yellowtail flounder.
2.5 2.0 Fishing Mortality (ages 4-6) 1.5 1.0 0.5 0.0 73 75 77 79 81 83 85 87 89 91 93 95 97 99 01 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 30 160 recruitment SSB 140 25 Spawning Biomass ('000s mt) Age-1 Abundance (millions) 120 20 100 15 80 60 10 40 5
20 0 0 19 19 19 19 1972 74 76 78 80 19 19 19 19 1982 84 86 88 90 19 19 19 19 2092 94 96 98 00 SSB Year; Recruitment Yearclass 36th SARC Consensus Summary 67
Figure A1.12b. Spawning stock and recruitment of southern New England - Mid Atlantic yellowtail flounder (points labeled by yearclass).
160 1980 140 1987 120 Recruitment (millions age- 1) 100 80 60 40 20 1991-1999 1972 0
0 5 10 15 20 25 30 Spawning Biomass ('000s mt) 68 36th SAW Consensus Summary
Figure A1.12c. Abundance at age of southern New England - Mid Atlantic yellowtail flounder.
-1970
-1975
-1980
-1985
-1990
-1995
-2000
-2005 0 1 2 3 4 5 6 7 Age 36th SARC Consensus Summary 69
70 Ag e -1 Ab und an ce ('000s )
SSB (m t)
F (4-6) 0 19 20000 40000 60000 80000 100000 120000 140000 160000 0 5000 10000 15000 20000 25000 30000 73 19 73 19 73 0 0.5 1 1.5 2 2.5 19 19 19 75 75 75 19 19 19 77 77 77 19 19 19 79 79 79 19 19 19 81 81 81 Figure A1.13. Retrospective analysis of the southern New England - Mid Atlantic 19 19 19 83 83 83 19 19 19 85 85 85 19 19 19 87 87 87 19 19 19 89 89 89 19 19 19 91 91 91 19 19 19 93 93 93 19 19 19 95 95 95 19 19 19 97 97 97 19 19 19 99 99 99 yellowtail flounder VPA.
20 20 20 36th SAW Consensus Summary 01 01 01
Figure A1.14. Results from biomass dynamics model (ASPIC) of southern New England
- Mid Atlantic yellowtail flounder, with age-based estimates (ADAPT) for comparison.
200 ASPIC 180 ADAPT 160 140 Stock Biomass (kt) 120 100 80 60 40 20 0
1935 1938 1941 1944 1947 1950 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 1.4 ASPIC ADAPT 1.2 Fishing Mortality on Biom ass 1.0 0.8 0.6 0.4 0.2 0.0 1935 1938 1941 1944 1947 1950 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 36th SARC Consensus Summary 71
Figure A1.15. Yield and biomass per recruit of southern New England - Mid Atlantic yellowtail flounder.
0.30 3.00 0.25 2.50 Yield per Recruit (kg) SSB per Recruit (kg) 0.20 2.00 0.15 YPR 1.50 SPR 0.10 1.00 0.05 0.50 0.00 0.00 0 0.5 1 1.5 2 Fishing Mortality 72 36th SAW Consensus Summary
Figure A1.16. Stochastic projection of southern New England - Mid Atlantic yellowtail flounder spawning biomass (top panel) and landings (bottom panel) at F=0.26, assuming long-term recruitment (dotted lines indicate 90% confidence limits, and the dashed horizontal line indicates SSBMSY).
140 120 100 80 S S B (kt) 60 40 20 0
02 04 06 08 10 12 14 16 18 20 22 24 26 20 20 20 20 20 20 20 20 20 20 20 20 20 30 25 20 Tota l Ca tch (kt) 15 10 5
0 02 04 06 08 10 12 14 16 18 20 22 24 26 20 20 20 20 20 20 20 20 20 20 20 20 20 36th SARC Consensus Summary 73
Figure A1.17. Stochastic projection of southern New England - Mid Atlantic yellowtail flounder spawning biomass (top panel) and landings (bottom panel) at a 2002 F of 0.77 and 2003-2009 F of 0.08, assuming long-term recruitment (dotted lines indicate 90%
confidence limits, and the dashed horizontal line indicates SSBMSY).
160 140 120 100 S S B (kt) 80 60 40 20 0
2002 2003 2004 2005 2006 2007 2008 2009 9
8 7
6 La ndings (kt) 5 4
3 2
1 0
2002 2003 2004 2005 2006 2007 2008 2009 74 36th SAW Consensus Summary
Figure A.1.18. Sensitivity analysis of MSY reference proxies for southern New England-Mid Atlantic yellowtail flounder, assuming different periods of recruitment (with 80%
confidence intervals).
350 300 250 SSBmsy (kt) 200 150 100 50 0
1963-2001 1973-2001 1992-2001 1963-1972 Recruitment Period 70 60 50 MSY (kt) 40 30 20 10 0
1963-2001 1973-2001 1992-2001 1963-1972 Recruitment Period 36th SARC Consensus Summary 75
A2. CAPE COD - GULF OF MAINE YELLOWTAIL FLOUNDER INTRODUCTION Yellowtail flounder, Limanda ferruginea, inhabit the continental shelf of the northwest Atlantic from Labrador to Chesapeake Bay (Bigelow and Schroeder 1953, Collette and Klein-MacPhee 2002). Off the U.S. coast, commercially important concentrations are found on Georges Bank, off southern New England, and off Cape Cod (statistical areas 514 and 521; Figure A2.1). Cape Cod yellowtail inhabit shallow water (10-60 m) relative to offshore yellowtail stocks (Lux 1964). Spawning occurs during spring and summer, peaking in late May. Larvae are pelagic for a month or more, then develop demersal form and settle to the bottom. Yellowtail flounder on the Cape Cod grounds generally mature at age-3 (OBrien et al. 1993) and grow to 58 cm total length.
A New England fishery for yellowtail flounder developed in the 1930s, coincident with a decline in winter flounder abundance, and the fishery expanded from southern New England to Georges bank and the Cape Cod grounds in the late 1930s and early 1940s (Royce et al. 1959, Lux 1964). On the Cape Cod grounds, yellowtail are generally caught in multi-species groundfish fisheries (principally by otter trawls) from late fall to spring, with some landings by gillnets in the winter and spring, but may also be specifically targeted in certain seasons (Royce et al. 1959).
Historically, landings from the Cape Cod grounds were a small portion of the total U.S.
yellowtail landings. However, during the collapse of Georges Bank and southern New England stocks in the early 1990s (NEFSC 1994), the Cape Cod stock was the most productive of the U.S. yellowtail stocks (Overholtz and Cadrin 1998).
The available information on yellowtail flounder stock structure off the northeast U.S.
indicates separate stocks on Georges Bank, off Cape Cod, and from southern New England to the Mid-Atlantic Bight. Distributional analyses indicate a relatively continuous distribution from the Mid Atlantic Bight to Nantucket Shoals, a concentration on Georges Bank, and a relatively separate concentration off Cape Cod (Royce et al.
1959). Geographic variation indicates that yellowtail off Cape Cod comprise a separate phenotypic stock than resources to the south (Begg et al. 1999). Tagging data indicate low dispersion from Cape Cod, Georges Bank and southern New England fishing grounds (Royce et al. 1959, Lux 1963). Descriptive information on early life history stages and circulation patterns suggest that yellowtail spawn in hydrographic retention areas, but there may be some advection of eggs and larvae from Georges Bank and Cape Cod to southern New England and the Mid Atlantic Bight (Sinclair 1988). In summary, yellowtail on the Cape Cod grounds can be considered a separate phenotypic stock (with some question on the northern boundary of the stock area). There is little evidence supporting separate stocks on the Cape Cod grounds and in the northern Gulf of Maine.
76 36th SAW Consensus Summary
Management History Over the past 25 years, the fishery for yellowtail flounder in federal waters has been managed under several regimes. From 1971 to 1976, national quotas were allocated by the International Commission for Northwest Atlantic Fisheries. From 1977 to 1982, the New England Fishery Management Council Atlantic Groundfish Fishery Management Plan established optimum yield thresholds for yellowtail west of 69o longitude (which included Cape Cod and southern New England yellowtail stocks) and imposed minimum mesh size, spawning closures, and trip limits (Table A2.1). In 1982, the Council adopted an Interim Groundfish Plan, which established a minimum size limit of 28 cm (11 in) and a minimum mesh size of 130 mm (5 1/8"; with exemptions). In 1983, the minimum mesh size was increased to 140 mm (5.5"; with exemptions) In 1986, the Councils Multispecies Fishery Management Plan increased the minimum legal size to 30 cm (12 in) and imposed seasonal area closures. Amendment #4 to the Plan further increased the minimum legal size to 33 cm (13 in) in 1989. In 1993, finfish exclusion devices were required in the northern shrimp fishery to reduce groundfish bycatch. Amendments #5,
- 6, and #7 (1994-1996), limited days at sea, closed areas year-round, further increased minimum mesh size to 142 mm (6 in diamond or square; with fewer exemptions),
imposed trip limits for groundfish bycatch in the sea scallop fishery, and prohibited small-mesh fisheries from landing groundfish. Framework #25 was an annual adjustment to the Multispecies Plan which prohibited bottom trawling in two areas of yellowtail habitat on the Cape Cod grounds in 1998: Massachusetts Bay was closed in March, and the waters off Cape Ann were closed in April. Other sections of the western Gulf of Maine were closed in May and June. The western Gulf of Maine closure is too deep to protect yellowtail flounder. Amendment #9 was adopted in 1998 to revise the overfishing definition according to Sustainable Fisheries Act requirements. In 1999, minimum twine top mesh of scallop dredges was increased from 203mm to 254mm to reduce yellowtail bycatch.
The portion of the Cape Cod yellowtail stock found within the Massachusetts territorial sea is managed by the Massachusetts Division of Marine Fisheries under a suite of management measures. Since 1931, many coastal areas have been closed to bottom trawling year-round (e.g. Winthrop Head to Gloucester), or seasonally (e.g. Boston to Provincetown and Gloucester to New Hampshire). The state has had a succession of more stringent size limits beginning with a 11" minimum size in 1982. The size limit increased to 12" in 1986 and then to 13" in 1988. In 1986, 5" mesh codends were required for trawling within the 20 fathom contour in waters north of Cape Cod. In 1986, a winter flounder spawning closure to trawling and gillnetting extending approximately one to two miles from shore was established in waters from the New Hampshire border to Provincetown from February 1 to April 30 (extended to May 31 in 1990). In 1989, small mesh trawling was restricted to permitted fisheries targeting specific species. In 1991, minimum mesh size throughout the net was increased to 5 1/2" north and east of Cape Cod. Since November 1, 1992 a year-round night closure to mobile gear has abbreviated fishing effort by curtailing trip fishing. Beginning in 1993, a Coastal Access Permit was required to fish mobile gear. The mesh size was increased again in 1994 to 6". A moratorium on new applicants for this permit was enacted in 1994 stemming an increase in effort into state waters. In 1995, the size limit for vessels fishing mobile gear was 36th SAW Consensus Summary 77
reduced from 90' registered length to 72' length over all. From 1995-1999, small mesh trawling in state waters north of Cape Cod was limited to an experimental whiting fishery with drastic ground gear modifications for bycatch reduction, prohibitions on groundfish retention and intensive sea sampling. Scallop dredge fisheries have been limited to 10' combined maximum dredge width since 1990. Gillnet fisheries in Massachusetts have a permit moratorium, 2400' maximum net length, 6" minimum mesh size and seasonally closed areas.
Assessment History Yellowtail resources on the Cape Cod fishing grounds and in the northern Gulf of Maine have been assessed and managed separately. The Cape Cod yellowtail resource was initially assessed by descriptive summaries of catch, effort, catch samples, survey indices, yield per recruit modeling, and estimates of total mortality rate (Z) from survey and commercial age samples. The stock was more stable than the Georges Bank or southern New England stocks from the 1940s to the 1960s, based on patterns of landings and commercial catch rates (Royce et al. 1959, Lux 1964). However in the early 1970s, effort began to increase, and catch rates began to decline (Parrack 1974). Estimates of fishing mortality rate (F) during the 1970s were at or above the estimated level of maximum yield per recruit (Howe 1975). Although yield remained stable relative to offshore stocks, catch rates were at the lowest levels observed by the late 1970s (Sissenwine et al. 1978). For a brief period in the mid 1970s, the stock appeared to be stable (McBride and Sissenwine 1979). However, by the late 1970s, peak catches produced high mortality rates, the age structure appeared to be truncated, and catch rates continued to decrease (McBride et al. 1980, McBride and Sissenwine 1980, Clark et al.
1981). Despite some indications of good recruitment in early 1980s (McBride and Clark 1983, Clark et al. 1984), landings and relative abundance generally decreased in the 1980s (NEFC 1986). The 1987 year class was dominant and contributed to some rebuilding, however, the most recent descriptive assessment of Cape Cod yellowtail concluded that the stock was overexploited (Rago 1994). An age-based assessment indicated that F was high (>0.7) from 1985 to 1997 and biomass was much less than BMSY (Cadrin et al. 1999). Updated assessments in 1999 and 2000 each indicated a reduction in F in the last year of the assessment (Cadrin and King 2000, Cadrin 2001),
but the revised estimate of 1998 F remained high (1.0, Cadrin 2001). An updated assessment of the Cape Cod yellowtail flounder stock was prepared concurrently with this assessment for the Groundfish Assessment Review Meeting (Cadrin and King 2002).
Yellowtail flounder in the northern Gulf of Maine have not been analytically assessed.
Royce et al. (1959) compiled yellowtail landings statistics for the scattered shoals in the northern Gulf of Maine in the 1940s, and Lux (1964) updated landings statistics through 1961. McBride and Sissenwine (1980) reported a substantial increase in yellowtail flounder landings from the northern Gulf of Maine during the 1970s, and described the sparse survey information available for yellowtail in the northern Gulf of Maine. This assessment combines catch and survey information from the Cape Cod grounds and the northern Gulf of Maine for a single-stock analysis.
78 36th SAW Consensus Summary
FISHERY DATA Commercial Landings Commercial statistics for Cape Cod yellowtail flounder are from statistical areas 514 and 521, and northern Gulf of Maine yellowtail are from statistical areas 511, 512, 513 and 515 (Figure A2.1). U.S. commercial landings of yellowtail flounder were derived from dealer weighout reports and canvas data according to historical assessment reports (Royce et al. 1959, Lux 1964, Sissenwine et al. 1978, McBride et al. 1980, McBride and Clark 1983, NEFC 1986). Previous to 1994, landings were allocated to statistical area, month, and gear type according to interview data collected by port agents (Burns et al.
1983). For 1994, landings reported by dealers were allocated to stock area using fishing vessel logbook data, by fishing gear, port, and season (Wigley, et al. 1998). For 1995-1997, dealers reported landings were prorated to stock area using a modified proration that included dealer codes (NEFSC 1998).
Annual landings generally increased from less than 1,000mt in the mid 1930s to a peak of 5,600mt in 1980 (Table A2.2, Figure A2.2). Landings decreased to approximately 1,200mt per year in the late 1980s, but peaked again in 1990 at 3,200mt with recruitment of the strong 1987 yearclass. Landings decreased to 800mt in 1993 and remained low through the 1990s, but rapidly increased to greater than 2,400mt in 2000 and 2001.
Landings at age of Cape Cod yellowtail flounder are described in Cadrin et al. (1999),
Cadrin and King (2000, 2002) and Cadrin (2001), and sample sizes are reported in Table A2.3. Very few port samples are available for the northern Gulf of Maine yellowtail fishery (six samples from 1969, 1976, 1983, 1987, 1988 and 1991), and all market categories were not sampled in any year. Therefore, the age distribution of Cape Cod yellowtail landings, by half and market category, were assumed for northern Gulf of Maine landings. Landings at age, by region, are listed in Table A2.4.
Discarded Catch Discards were estimated using discard to kept observations from 1989-2001 sea sampling for the trawl and gillnet fisheries and discard per effort for the shrimp and scallop fisheries as described in Cadrin et al. (1999). Discards at age of Cape Cod yellowtail flounder for 1985-1997 are described in Cadrin et al. (1999), and for 1998-2001 by Cadrin and King 2002 (Table A2.5a). Discards for the northern Gulf of Maine averaged 38% of Gulf of Maine yellowtail landings, primarily from the trawl fishery and the shrimp fishery prior to the Nordmore grate requirement in 1993 (Table A2.5b). Discards for 1985-1988 were approximated by assuming a 38% annual discard ratio.
Discards at age of Cape Cod yellowtail flounder are described in Cadrin et al. (1999) and Cadrin and King (2002; Table A2.6a). Discards at age for yellowtail in the northern Gulf of Maine were estimated using length observations from sea sampling (Table A2.6b; using pooled-year samples by half and gear for unsampled discards) and survey age-length keys for 1989-2001, by half-year. The proportion discard at age from the Cape Cod grounds were assumed for 1985-1988 discards in the northern Gulf of Maine. Total catch at age is dominated by age-3 and indicates a strong 1987 yearclass (Appendix A, 36th SAW Consensus Summary 79
Figure A2.3). Mean weight at age of catch was relatively stable from 1985 to 1996, but has increased for ages 2+ in recent years (Figure A2.4).
ABUNDANCE AND BIOMASS INDICES Stock Abundance and Biomass Indices NEFSC survey strata for the Cape Cod grounds are offshore strata 25-27 and inshore strata 56-66 and strata for the northern Gulf of Maine are offshore strata 39 and 40 (Figure A2.5). The NEFSC spring and autumn bottom trawl surveys have sampled offshore strata since 1963 and 1968, respectively (Despres et al. 1988). However, sampling of inshore strata north of Cape Cod began in 1977. Yellowtail are consistently sampled in offshore stratum 27 by the spring survey, but were only caught in 4 years since 1963 by the fall survey. Therefore, the spring index includes offshore stratum 27, but the fall survey does not.
Survey biomass indices are somewhat noisy, but generally indicate high biomass in the late 1970s and early 1980s, a decline in the 1980s and a rapid increase in the late 1990s (Figure A2.6). The rapid increases in fall 1999 or spring 2000 do not appear to result from strong recruitment, because catches of all ages increased. Large survey catches were distributed throughout Cape Cod and Massachusetts Bays, Stellwagen Bank and Jeffreys Ledge (Figure A2.7).
The portion of survey biomass from northern Gulf of Maine is variable, but averages 11% throughout the survey time series (Figure A2.8). There appears to have been low abundance of yellowtail in the northern Gulf of Maine during the late 1960s, early 1970s, and middle 1980s. Age distribution of survey catches are potted in Figure A2.9 and listed in Table A2.8.
Correspondence among survey indices was assessed using correlations among normalized observations [Ln(x/mean); Table A2.7]. Correlations among survey series were weak to moderate with strongest correlations among indices for ages 2-4 (r=0.12 to 0.69). Normalized indices of catch per tow at age are illustrated in Figure A2.10.
MORTALITY AND STOCK SIZE Virtual Population Analysis Estimates of abundance from virtual population analysis of catch at age-1 to age-5+,
1985-2001, were calibrated using an ADAPT algorithm (Gavaris 1988) that estimated age 2-4 survivors in 2002 and survey catchability coefficients (q) using nonlinear least squares of survey observation errors. Abundance at age was calibrated with survey indices of abundance: spring and winter survey indices (age-1 to age-5+) were calibrated to January abundance, and fall survey indices (age-1 to age-4+) were calibrated to abundance for January of the next year. The instantaneous rate of natural mortality (M) was assumed to be 0.2 based on tag returns (Lux 1969), relationships of Z to effort 80 36th SAW Consensus Summary
(Brown and Hennemuth 1971), and the oldest individual sampled in the stock area (age-14). Although catches of yellowtail older than age-8 are rare in commercial or research catches, the stock has been heavily exploited for seven decades. Maturity at age for Cape Cod yellowtail flounder was reported by OBrien et al. (1993) from 1985-1990 NEFSC spring survey samples. Model Residuals are plotted in Figure A2.11.
Results indicate that F on ages 3+ decreased from a peak of 1.3 in 1988 to 0.28 in 1993, then increased to an annual average of 0.61 from 1995 to 2000 and was 0.75 in 2001 (Table A2.9, Figure A2.12). With the exception of the strong 1987 year class (29 million at age-1), recruitment has been stable, averaging 10 million at age 1. However, early indications are that the 2000 yearclass is well below average. Spawning biomass averaged 1,000mt during the late 1980s increased to a peak of 3,800mt in 1991 as the 1987 cohort matured, decreased to 1,600mt in 1998, and gradually increased to 3,200 mt in 2001. Retrospective analysis indicates a pattern of underestimating F, and overestimating SSB in the last five years (Figure A2.13).
Bootstrap analysis indicates that abundance estimates in 2002 were estimated with moderate precision (CVs=0.26-0.51). The 80% confidence limit for 2001 F is 0.59-0.95, and the 80% confidence limit for 2001 SSB is 2,500-4,000mt.
Biological Reference Points Yield and biomass per recruit were calculated assuming the observed partial recruitment and mean weight at age for 1994-2001 (Thompson and Bell 1934). Results are reported in Table A2.10 and shown in Figure A2.14. A comparison of recently observed age distributions with the age distribution expected at F40% shows a relative truncation in current age structure (Figure A2.15). Applying the approach used to estimate MSY proxies for Cape Cod yellowtail (NEFSC 2002), FMSY is approximated as F40%MSP (0.17).
The SSBMSY proxy is 12,600mt, calculated as the product of 40%MSP (1.192kg spawning biomass) and average recruitment (10.5 million). The MSY proxy is 2,300mt, derived as the product of yield per recruit at F40%MSP (0.213kg) and average recruitment.
Projections Stochastic projections at 85% of status quo F in 2002 and F=0.03 for 2003-2009 there is a 50% probability of rebuilding to SSBMSY by 2009 (Appendix A, Figure A2.16).
However, retrospective patterns indicate that projections may be optimistic.
WORKING GROUP DISCUSSION Stock Structure The WG reviewed seven working papers/presentations on yellowtail stock structure.
With respect to spatiotemporal patterns of abundance, the WG noted that recruitment trends of Cape Cod and southern New England yellowtail indicated possible autocorrelation, as evidenced by a common series of several years of poor recruitment that might be indicative of a common stock. The WG noted that historical tagging data 36th SAW Consensus Summary 81
indicate weak movement between the Cape Cod, Georges Bank, and other areas, but strong mixing between Mid Atlantic and southern New England areas, that might be indicative of a common Mid Atlantic-southern New England stock. The WG noted limited evidence in the literature to separate Gulf of Maine fish from the Cape Cod stock.
The WG supported the major conclusion of working paper A1 that information available from the literature indicates separate yellowtail flounder stocks on Georges Bank, off Cape Cod, and in the Southern New England-Mid Atlantic Bight area.
The Working Group reviewed the evidence available in the scientific literature for different assumptions about yellowtail flounder stock structure based on 1) geographic distribution of the fish and fishing patterns, 2) geographic variation of genetics, life history patterns, recruitment, and morphology, 3) movements and migration of ichthyoplankton and juvenile/adult fish, and 4) previous Amulti-approach@ assessments which considered many of these factors in developing stock structure assumptions for assessment. Geographic analyses indicate a relatively continuous distribution of yellowtail flounder from the Mid Atlantic Bight to Nantucket Shoals, a concentration on Georges Bank, and a relatively separate concentration off Cape Cod. Geographic variation in life history parameters indicates that yellowtail off Cape Cod comprise a separate phenotypic stock than resources to the south. Historical tagging data indicate less than 3% dispersion from Cape Cod, Georges Bank and southern New England fishing grounds. Descriptive information on early life history stages and circulation patterns suggest that yellowtail spawn in hydrographic retention areas, but that there may be some advection of eggs and larvae from Georges Bank and Cape Cod to Southern New England and the Mid Atlantic Bight.
The Working Group reviewed spatiotemporal patterns in the abundance of yellowtail for evidence of stock structure. The overwhelming pattern indicated by cluster analysis was a difference between northern and southern survey strata, with southern strata having peaks of abundance in the early and late 1980s and northern strata having a general increase abundance increasing in northern strata during the 1990s and having no trend in southern strata. The boundary between the two major clusters is between southwestern Georges Bank and Nantucket Shoals, particularly the southwestern part, where survey catches reflect both southern and northern peaks in abundance. The WG noted that the GIS and multivariate analyses did not provide strong evidence for separation of the CC and GOM stocks. The WG supported the major conclusions that 1) there are two major groups of NEFSC survey strata based on patterns of abundance over time, with a boundary on southwestern GB (northern: GOM, CC, and GB areas; southern: MA and SNE areas), and 2) the current analyses confirm earlier conclusions of separate Aharvest stocks@ on GB and off SNE. Correlation analysis of survey data generally confirmed the multivariate analysis by stratum. Survey indices and landings were strongly correlated between southern New England and the mid-Atlantic, not correlated between southern New England and Cape Cod or southern New England and Georges bank, and moderately correlated between Georges Bank and Cape Cod.
The Working Group reviewed geographic variation in growth and maturity of yellowtail as the basis for stock structure assumptions, using spatial and multivariate statistical 82 36th SAW Consensus Summary
analyses. A nineteen-year time series of NEFSC survey observations was analyzed to investigate patterns of variation in nine life history variables (male mean length at ages 2-4, female mean length at ages 2-4, male maturity at age-2, and female maturity at ages 2 and 3) among survey strata. Life history characters are strongly correlated and vary significantly among stock areas as well as 5-year time periods. The major pattern of variance was faster growth and maturation in southern stocks (GB, SNE, and MA) and slower growth and maturation in northern stocks (Scotian Shelf and CC). Life history characters are generally homogeneous within the southern areas and within the northern areas, with some intermediate observations in the CC area. One survey stratum east of Cape Cod was identified that had life history observations that were consistently more similar to observations in SNE than to other observations in the Cape Cod area. The WG supported the major conclusion that geographic patterns of variation in size at age and proportion mature at age indicate two phenotypic stocks of yellowtail flounder off the northeastern United States, with a boundary east of Cape Cod.
The Working Group reviewed information on morphometric (fish body measurement) variation of yellowtail flounder as the basis for stock structure assumptions, using image analysis and multivariate statistical analysis. Significant morphometric variation was found between sexes of yellowtail flounder and among eight geographic areas, from the Grand Bank to the Mid-Atlantic Bight. Yellowtail sampled off Newfoundland had relatively shorter bodies than those from south of Nova Scotia. Extrinsic classification accuracy of males and females to the correct Canadian area was 71-95%, but was lower for areas off the northeastern United States (43-76%). Females had relatively deeper abdomens and larger heads than males.
The WG noted that previous investigators (e.g., Lux 1963) found no significant differences in meristics (e.g., fin and ray counts) among U.S. stocks, supporting the current morphometric work. The WG also noted that the results of the morphometric work coincides with the differences in growth noted between U.S. and Newfoundland stocks. The WG supported the conclusion that morphometric variation among U.S.
yellowtail flounder groups is not sufficient for accurate classification to stock area.
The Working Group reviewed an exploratory analysis of patterns of yellowtail larval drift for evidence of stock structure. Changes in the geographic distribution of yellowtail flounder eggs and larvae over the course of the spawning season suggest broad-scale larval drift. Evidence of similar distributional changes from the location of the spawners to that of the eggs, however, is confounded by limitations in survey timing. The WG supported the conclusion of working paper A4 that qualitative spatial analyses indicate a general southwesterly movement of yellowtail flounder larvae along the continental shelf of the northeastern United States.
The Working Group reviewed genetic analyses that attempted to find evidence for yellowtail flounder stock structure. The objective of this work is to define stocks based on genetic markers, using methods (RAPD-PCR) which can resolve DNA Afingerprints@
from the sampled muscle tissue of individual fish. Frequency patterns of DNA Abanding@ are obtained which are examined for differences between fish from the MA, 36th SAW Consensus Summary 83
SNE, GB, CC, and GOM stocks. Results for two DNA primers, which provided 28 characteristic bands, provided no evidence of extensive population structure for yellowtail flounder sampled from the MA to GOM areas. Future work will attempt to use other methods, such as the examination of nuclear and/or mitochondrial DNA, to look for differences among groups of yellowtail flounder.
The WG noted that the number of migrants per generation between the yellowtail stock areas, although probably low, is likely sufficient to prevent detection of significant genetic differences using RAPD-PCR. The WG noted that the expression of phenotypic differences may not be evident in the genome, or may be very difficult to detect (many different primers may have to be tested to find one that isolates the gene responsible for a given phenotypic expression). The WG supported the conclusion of presentation A6 that, at this time, yellowtail flounder stock differentiation must be based on factors other than genetics.
The current work reviewed by the WG indicates no genetic difference among yellowtail flounder on U.S. fishing grounds. Patterns over time in landings and survey indices suggest two harvest stocks with a boundary between Georges Bank and Southern New England. Differences in life history characteristics suggest two phenotypic stocks with a boundary off Cape Cod. The WG noted that the most important potential Amisalignments@ with respect to current or proposed stock definitions are in areas 521, 525, and 526 (and associated NEFSC survey strata 10, 13 and 25), where fish from adjacent stocks may overlap during times of abundance. However, the WG found no strong evidence in patterns of fishery landings, survey abundance indices, or life history parameters to suggest that revision of the current assignment to stock areas of these particular statistical areas or survey strata is appropriate. Further, the WG did not find significant justification for the inclusion of fish caught in area 4 (i.e., Canadian landings) to the CC-GOM stock. The WG concluded that current evidence indicates that three stock areas are appropriate for yellowtail flounder: 1) a GB stock including fish landed from NEFSC statistical areas 522, 525, 551-552, and 561-562, and associated NEFSC survey strata (i.e., the current stock definition used in U.S. and Canadian assessments), 2) a SNE-MA stock including fish landed from areas 526, 533-539, 541, and 611-639, and associated NEFSC survey strata, and 3) a CC-GOM stock including fish landed from areas 511-521, and associated NEFSC survey strata. Finally, the WG recommends that assessment scientists explore the potential to classify yellowtail in fishery and survey samples to stock in the Aoverlap/transition@ areas based on age structure characteristics.
Stock Assessment The Working group discussed the sharp increase in catch and survey indices from 1999 to 2001. The Group speculated that rolling closures may have increased both survey and fishery catchability. Surrounding closures may have redirected effort onto Stellwagen Bank. The Group noted that sharp increases also occurred in historic landings (Figure A2.2).
The Working Group noted that sampling improved since last assessment, with samples in each market category and season. The mean weight at ages 3-5 increased in the catch.
84 36th SAW Consensus Summary
The Group considered the possibility that mean weights were poorly estimated in early part of time series when sampling coverage was poor. Therefore, the Group agreed that as many years as possible should be included to derive the mean weights and partial recruitment at age for reference point estimation and projections.
The Working group agreed to revise the calibration configuration from previous assessments by including all age 5 and 6+ indices. The change was made to reduce the substantial positive bias in the age-5 abundance estimate when those indices were excluded.
The Working Group was concerned that projections may not be reliable because of retrospective error. They noted that retrospective inconsistencies are worst for older ages, but could not determine if the source of the errors was in the catch data or assumptions such as M or F on the oldest age. Although estimates from the assessment are imprecise and perhaps biased, the Group concluded that F is high. The truncated age structure in the surveys and catch confirm that mortality is high.
Despite the high F, stock size appears to be increasing. However, the same impression was given by recent assessments, only to have stock size estimates decrease when the assessments were updated. The Group noted that the problems in the assessment may result from the relatively short time series of catch at age and little contrast in the data.
The Group investigated the possibility that older fish are moving from the fishing and survey areas, giving the false impression of high mortality. Size distributions from the longest time series of survey data (fall survey, offshore strata 25, 26, 39 and 40; Figure A2.17) show that larger fish were sampled in the assessment strata in the 1960s, but recent length distributions are considerably smaller. More large fish were also sampled in the earliest years of the Massachusetts survey (Figure A2.18). The Gulf of Maine summer survey, which sampled the inshore strata of the western Gulf of Maine (1977-1981, inshore strata 68-90; Figure A2.19) caught a similar size distribution of yellowtail as the assessment strata. Survey catches in the central and eastern Gulf of Maine also caught a similar size distribution of yellowtail as the assessment strata (Figure A2.20),
but inconsistently and at much lower densities than those in the assessment strata (e.g.,
since 1963, yellowtail were only caught twice in stratum 28, six surveys in stratum 29, six surveys in stratum 37 and once in stratum 38). Therefore, the assessment strata appear to reflect the size distribution throughout the Gulf of Maine, and no large yellowtail were sampled anywhere in the Gulf of Maine in recent years.
SARC DISCUSSION The original ADAPT run used age 1-6+ catch at age formulation and exhibited a severe retrospective pattern for SSB and F. A comparison of ADAPT retrospective patterns from Cape Cod-Gulf of Maine and Cape Cod only exhibited little difference. The low numbers of age 5 in the catch and surveys did not appear to be sufficient to reliably estimate F on age 5. The GARM noted that the high F seems inconsistent with level or increasing SSB and increasing survey indices. A lot of discussion centered on how this could be possible, 36th SAW Consensus Summary 85
without a consensus regarding cause. It was suggested that the high F means that the tuning is actually only working on the oldest age group. Similarly, the estimated catchabilities increase without reaching an asymptote with increasing age. Also, the SARC observed that F (4-5) may not be a good estimator of F on the population since a large portion of the catch is age-3 As a result, an alternate ADAPT run which truncated the catch at age to age-5+ was considered. Estimation of abundance for the truncated catch at age required that age 3 be considered fully recruited for calculation of F on the oldest true age. The alternate Adapt run reduced the magnitude of the retrospective patterns for fully recruited F and spawning biomass. The results revealed a high sensitivity to the calibration change. The fully recruited F decreased while spawning stock biomass increased.
Including a flat-topped selectivity pattern at age 3+ could mask high Fs at true fully recruited ages. The original formulation, which estimated F on age 3, suggested that age 3 yellowtail were partially recruited. A comparison of observed length distribution at age-3 and length selectivity at various mesh sizes indicated only partial retention of age-3 yellowtail. However, mesh selectivity is only one component of fishery selectivity and other factors, such as temporal-spatial elements of the fishery, also influence fishery selectivity. In addition, the mean weights of a plus group at age-5 and older may be difficult to characterize because they continue to grow substantially after age 5.
Age determination does not seem to be a problem with this stock, especially for the young ages in the catch. However, the sampling of catch could be causing a problem, particularly in the Gulf of Maine. The lack of contrast in the VPA time series may lead to imprecise estimate of survey catchability. The time series begins in 1985 due to few commercial samples prior to 1985.
The possibility of contributions from the Georges Bank and/or Southern New England stocks of yellowtail flounder to the Cape Cod-Gulf of Maine stock was discussed in terms of both adult movement and recruitment impacts. Given the relative sizes of the stocks, especially the Georges Bank and Cape Cod stocks, any transfer among stocks could overwhelm the signal from Cape Cod.
The revised ADAPT formulation, which uses average fully recruited F on ages 3 and 4 required re-estimating yield per recruit and biological reference points. Several concerns about including the partially recruited age 3 in the average of fully recruited F were raised. However, the YPR and biological reference points were re-estimated using age 3 as fully recruited in order to be consistent with the revised Adapt configuration.
An examination of stock-recruit observations for Cape Cod-Gulf of Maine yellowtail and fishing mortality rates at various levels of replacement suggests that the stock can replace itself at F greater than F40% (i.e.Fmed > F40% MSP) and F40% may be a conservative proxy for FMSY. However, extrapolating recruitment at high stock sizes from the VPA time series may overestimate productivity of the stock at higher SSB. The stock recruitment relationship is similar to the Georges Bank stock prior to recovery, in that most stock 86 36th SAW Consensus Summary
recruitment points were above the F40% replacement line. This suggests that a short-term perspective of the stock recruitment relationship may not represent the potential productivity of the Cape Cod-Gulf of Maine stock. The SARC concluded that there is currently no justification for changing theF40% reference point.
Sources of Uncertainty o Very few length samples were available from the relatively small Gulf of Maine catch.
o There was an apparent increase in survey availability in Fall 1999 and Spring 2000 surveys. These recent observations have a large influence on the ADAPT calibration.
o Relative yearclass strengths are not tracked well over time by the surveys, indicating that survey availability has been variable throughout the time series.
o Spawning stock biomass calculations are based on a constant maturity at age assumption. Changes in maturity at age have not been investigated.
o The degree of mixing between Cape Cod-Gulf of Maine yellowtail and adjacent stocks is not precisely known. Substantial mixing may confound population estimates.
o Estimation of the very small 2000 year class may change in future assessments.
Previous estimates of recruitment in the most recent year have changed substantially as assessments were updated.
o Lack of contrast in the recruitment time series limits the perception of SSBMSY.
Research Recommendations o Tagging studies should be planned to examine movements and to independently estimate F. Early tagging studies may have been conducted during different temperature regimes.
o Commercial length and age samples from the Gulf of Maine region are needed.
o The use of parametric models to estimate MSY based reference points should be explored.
o Consider using a forward-projection statistical catch at age model.
o Incorporate the State of Maine inshore survey data in the assessment.
o Alternative indices of abundance should be explored, such as industry surveys, study fleets, and a flatfish survey.
o Increase observer sampling on the exempted whiting fishery, particularly to confirm low bycatch observations for the recently required raised footrope.
o Sample inshore NEFSC survey strata more consistently.
o Continue investigation of geographic patterns in sex ratios and maturity at age.
Evaluate possible revisions of survey sampling and data processing protocol to obtain abundance indices by sex.
o Evaluate information on dimorphic growth rates.
o Explore stock identification techniques for additional information on stock boundaries and rates of movement among stock areas.
o Unique gear codes for small-mesh fisheries (similar to negear=058 or gearcode=OTS for shrimp trawls) would greatly benefit estimation of discards.
36th SAW Consensus Summary 87
o Continue processing archived age samples from MADMF surveys to eliminate using NEFSC age keys as noted and process NEFSC observer age samples.
o Revise historical small-mesh discard estimates so that the shrimp and whiting fisheries are treated separately.
o Investigate information available on discard mortality of yellowtail flounder.
o Explore post-stratification of survey data in NEFSC stratum 24 and inshore strata.
REFERENCES Begg, G.A., J.A. Hare, and D.D. Sheehan 1999. The role of life history parameters as indicators of stock structure. Fish. Res. 43: 141-163.
Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fish. Bull. 53: 1-577.
Brown, B.E. and R.C. Hennemuth. 1971a. Assessment of the yellowtail flounder fishery in subarea 5. ICNAF Res. Doc. 71/14.
Burns, T.S., R. Schultz, and B.E. Brown. 1983. The commercial catch sampling program in the northeastern United States. Can. Spec. Pub. Fish. Aquat. Sci. 66.
Cadrin, S.X. 2001. Cape Cod yellowtail flounder. In Assessment of 19 Northeast Groundfish Stocks through 2000. NEFSC Ref. Doc. 01-20: 67-79.
Cadrin, S.X. and J. King. 2000. Cape Cod yellowtail flounder. In Assessment of 11 Northeast Groundfish Stocks through 1999. NEFSC Ref. Doc. 00-05: 83-98.
Cadrin, S.X. and J. King. 2002. Cape Cod yellowtail flounder. Groundfish Assessment Review Meeting Working Paper E.
Cadrin, S.X., J. King and L. Suslowicz. 1999. Status of the Cape Cod yellowtail flounder stock for 1998. NEFSC Ref. Doc. 99-04.
Clark, S.H., L. OBrien, and R.K. Mayo. 1981. Yellowtail flounder stock status. NEFC Lab. Ref. Doc. 81-10.
Clark, S.H., M.M. McBride and B. Wells. 1984. Yellowtail flounder assessment update -
1984. NEFC Lab. Ref. Doc. 84-39.
Collette, B.B. and G. Klein-MacPhee. 2002. Bigelow and Schroeders Fishes of the Gulf of Maine. Smithsonian Press, Washington, D.C.
Despres, L. I., T. R. Azarovitz, and C. J. Byrne. 1988. Twenty-five years of fish surveys in the northwest Atlantic: the NMFS Northeast Fisheries Centers bottom trawl survey program. Mar. Fish. Rev. 50(4): 69-71.
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Gavaris, S. 1988. An adaptive framework for the estimation of population size. CAFSAC Res. Doc. 88/29.
Howe, A.B. 1975. Yellowtail flounder yield dynamics in the north shore closure area.
MADMF unpublished report.
Lux, F.E. 1963. Identification of New England yellowtail flounder groups. Fish. Bull. 63:
1-10.
Lux, F.E. 1964. Landings, fishing effort, and apparent abundance in the yellowtail flounder fishery. ICNAF Res. Bull. No. 1: 5-21.
Lux, F.E. 1969. Landings per unit effort, age composition, and total mortality of yellowtail flounder, Limanda ferruginea (Storer), off New England. ICNAF Res. Bul.
6:47-69.
McBride, M.M. and B.E. Brown 1980. The status of the marine fishery resources of the northeastern United States. NOAA Tech. Mem. NMFS-F/NEC-5.
McBride, M.M. and S.H. Clark. 1983. Assessment status of yellowtail flounder (Limanda ferruginea) stocks off the northeastern United States. NEFC Lab. Ref. Doc. 83-32.
McBride, M.M. and M.P. Sissenwine. 1979. Yellowtail flounder (Limanda ferruginea) status of the stocks, February 1979. NEFC Lab. Ref. Doc. 79-06.
McBride, M.M. and M.P. Sissenwine. 1980. Yellowtail flounder of the Cape Cod area and northern Gulf of Maine. NEFC Lab. Ref. Doc. 80-16.
McBride, M.M., M.P. Sissenwine, B.E. Brown and L.M. Kerr. 1980. Yellowtail flounder (Limanda ferruginea) status of the stocks, March 1980. NEFC Lab. Ref. Doc. 80-20.
NEFC (Northeast Fisheries Center) 1986. Report of the second NEFC stock assessment workshop (second SAW). NEFC Ref. Doc. 86-09.
NEFSC (Northeast Fisheries Science Center) 1994. 1994. Special advisory on groundfish status on Georges Bank. In: Report of the 18th Northeast Regional Stock Assessment Workshop (18th SAW) the plenary.
NEFSC (Northeast Fisheries Science Center) 1998. 27th northeast regional stock assessment workshop (27th SAW). NEFC Ref. Doc. 98-15.
NEFSC (Northeast Fisheries Science Center). 2002. Final report of the Working Group on Re-Evaluation of Biological Reference Points for New England Groundfish. 19 March, 2002.
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OBrien, L., J. Burnett, and R.K. Mayo. 1993. Maturation of nineteen species of finfish off the northeast coast of the United States, 1985-1990. NOAA Tech. Rep. NMFS 113.
Overholtz, W. and S.X. Cadrin. 1998. Yellowtail flounder. NOAA Tech. Rep. NMFS-NE-115: 70-74.
Parrack, M. 1974. Status review of ICNAF subarea 5 and statistical area 6 yellowtail flounder stocks. ICNAF Res. Doc. 74/99.
Rago, P. 1994. Yellowtail flounder. NOAA Tech. Rep. NMFS-NE-108: 64-68.
Royce, W.F., R.J. Buller, and E.D. Premetz. 1959. Decline of the yellowtail flounder (Limanda ferruginea) off New England. Fish. Bull. 146: 169-267.
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Table A2.1. Summary of management of Cape Cod-Gulf of Maine yellowtail flounder.
Year Comments FCMA implemented March 1 1977 Groundfish plan adopts quotas for cod, haddock, yellowtail flounder Interim Groundfish Plan adopted:
Georges Bank and Gulf of Maine minimum mesh size of 5 1/8 inches, increasing to 5 1/2 inches in 1983 11 inch minimum size for yellowtail 1982 Scallop FMP implemented Northeast Multispecies FMP adopted:
Minimum size for yellowtail flounder: 12 inches Minimum mesh size in GB/GOM: 5 1/2 inch cod end (no minimum size in SNE/MA)
Seasonal yellowtail closure, March - May, between 69-30 and 72-30W Small mesh fisheries in GOM/GB area only restricted to specific seasons with limits on landings (not 1986 catch) of groundfish and inshore area of GOM Amendment 2:
1989 Yellowtail minimum size increased to 13 inches Amendment 4:
Tightened restrictions on carrying small mesh while in Regulated Mesh Areas 1991 Mandated use of selective gear in shrimp fishery, leading to implementation of the Nordmore grate in 1993 Amendment 5 and emergency regulations:
DAS limits for most vessels West of 72-30W. Mesh determined by mesh requirements of summer flounder fishery (5 1/2 inch diamond or 6 inch square)
GOM/GB mesh of 6 inches (diamond or square)
Eliminated seasonal restrictions on small mesh fisheries in Small Mesh Exemption Area of inshore GOM Adopted Nordmore grate requirement into FMP Scallop Amendment 4: adopted permit moratorium, effort control/DAS program, 5.5 inch twine top 1994 minimum, and crew limits Amendment 7 Extended DAS limits to most vessels Limited possession of groundfish by scallop vessels to 300 pounds of regulated multispecies Established criteria for exempted fisheries Established exempted whiting fisheries in GOM/GB in three areas (Small Mesh Areas I and II in inshore 1996 GOM, Cultivator Shoals area on GB)
Framework 27: (May 1)
Increased square mesh minimum size to 6 1/2 inches in GOM/GB/SNE Regulated mesh areas 1999 Framework 29: (June)
Amendment 9: (November): Revised overfishing definitions Scallop Framework 11 mandates 8 inch twine top, authorizes scallop access program for Closed Area II, with yellowtail flounder bycatch limits Scallop Framework 13: Scallop vessel closed area access programs with yellowtail bycatch limits Adopted management measures for small-mesh multispecies, establishing minimum mesh sizes and trip/possession limits to reduce mortality on silver, red, and offshore hake Framework 35:
2000 Established exempted whiting fishery in upper Cape Cod Bay using raised footrope trawl 36th SAW Consensus Summary 91
Table A2.2. Cape Cod - Gulf of Maine yellowtail flounder catch.
Cape Cod Cape Cod Gulf of Maine Gulf of Maine Landings Discards Landings Discards Total 1960 1,500 500 39 --- 2,039 1961 1,800 600 22 --- 2,422 1962 1,900 600 0 --- 2,500 1963 3,600 1,000 0 --- 4,600 1964 1,851 600 6 --- 2,457 1965 1,498 500 8 --- 2,006 1966 1,808 300 26 --- 2,135 1967 1,542 800 50 --- 2,391 1968 1,569 600 13 --- 2,181 1969 1,346 300 75 --- 1,722 1970 1,185 400 125 --- 1,710 1971 1,662 700 56 --- 2,418 1972 1,364 300 156 --- 1,821 1973 1,662 0 63 --- 1,724 1974 2,054 200 104 --- 2,358 1975 2,027 0 194 --- 2,220 1976 3,587 100 258 --- 3,945 1977 3,469 0 252 --- 3,722 1978 3,683 400 388 --- 4,471 1979 4,163 500 276 --- 4,939 1980 5,106 600 461 --- 6,167 1981 3,149 600 425 --- 4,174 1982 3,150 400 486 --- 4,035 1983 1,884 300 324 --- 2,509 1984 1,121 20 244 --- 1,385 1985 967 77 205 77 1,326 1986 1,041 305 164 62 1,572 1987 1,159 198 194 73 1,624 1988 1,085 283 190 72 1,630 1989 909 390 209 47 1,555 1990 2,984 1,141 238 98 4,461 1991 1,472 405 265 110 2,251 1992 828 637 203 78 1,746 1993 628 90 158 31 907 1994 978 192 321 89 1,580 1995 1,207 233 124 111 1,674 1996 1,064 182 108 51 1,405 1997 1,040 257 74 20 1,392 1998 1,169 259 73 39 1,540 1999 1,089 107 121 40 1,357 2000 2,279 163 133 33 2,609 2001 2,362 447 143 35 2,988 92 36th SAW Consensus Summary
Table A2.3. Samples of Cape Cod yellowtail flounder.
unclass. small large Year half trips lengths lengths lengths ages 1985 1 5 109 304 196 292 2 12 0 825 543 357 1986 1 4 0 608 206 217 2 6 0 321 172 240 1987 1 6 0 300 352 353 2 5 0 284 269 207 1988 1 6 0 477 267 286 2 5 0 291 364 252 1989 1 6 10 261 314 305 2 4 97 262 173 200 1990 1 8 536 532 374 339 2 6 636 429 276 137 1991 1 8 811 501 332 610 2 7 109 531 242 277 1992 1 4 707 126 254 339 2 7 136 262 457 268 1993 1 3 170 145 182 177 2 3 273 244 74 114 1994 1 4 100 261 170 273 2 3 0 106 144 149 1995 1 4 39 276 201 196 2 6 998 392 275 157 1996 1 1 2560 0 87 196 2 12 118 495 640 485 1997 1 7 343 388 483 556 2 17 317 996 869 634 1998 1 7 4781 0 508 195 2 6 165 0 600 165 1999 1 4 2501 278 60 49 2 4 1024 268 116 57 2000 1 46 521 723 2775 903 2 15 0 566 1057 395 2001 1 8 3502 251 570 192 2 16 1950 393 774 436 36th SAW Consensus Summary 93
Table A2.4a. Landings at age of Cape Cod yellowtail flounder.
Landings at age (thousands) age 1 2 3 4 5 6 7 8+ sum 1985 5 738 700 522 268 89 3 7 2,332 1986 0 1,998 579 223 32 6 0 1 2,838 1987 0 609 1,786 268 100 29 12 5 2,808 1988 1 802 1,043 625 172 36 0 0 2,679 1989 0 726 989 231 31 3 2 2 1,986 1990 0 692 6,191 416 32 16 7 3 7,357 1991 0 311 903 1,455 249 33 27 1 2,978 1992 0 338 807 514 150 6 5 1 1,821 1993 0 25 684 573 90 24 15 7 1,418 1994 0 87 1,023 650 236 65 38 9 2,109 1995 0 233 1,730 808 152 78 5 0 3,006 1996 0 150 1,097 798 287 11 5 2 2,349 1997 0 481 1,086 702 160 13 0 1 2,443 1998 0 257 1,681 472 141 41 3 0 2,595 1999 0 328 1,134 646 106 43 1 0 2,258 2000 0 942 2,625 1,152 138 18 13 3 4,891 2001 0 807 2,933 1,058 152 24 13 1 4,987 mean 0 518 1,429 594 147 33 8 3 2,732 Landed weight at age (kg) age 1 2 3 4 5 6 7 8+
1985 0.19 0.32 0.37 0.49 0.60 0.73 1.20 1.39 1986 0.32 0.46 0.57 0.73 0.90 --- 1.40 1987 0.31 0.42 0.55 0.65 0.81 1.03 1.18 1988 0.11 0.31 0.37 0.53 0.70 0.85 --- ---
1989 0.38 0.45 0.65 0.92 1.41 1.24 1.24 1990 0.31 0.41 0.56 0.82 0.90 0.99 1.17 1991 0.35 0.39 0.54 0.74 0.99 1.06 1.01 1992 0.32 0.41 0.53 0.61 0.73 1.53 1.91 1993 0.31 0.38 0.43 0.74 0.95 1.01 1.17 1994 0.29 0.38 0.50 0.62 0.68 1.04 1.11 1995 0.35 0.36 0.43 0.61 0.78 1.11 ---
1996 0.32 0.42 0.50 0.53 0.91 1.19 1.18 1997 0.39 0.41 0.47 0.57 0.78 1.30 1.31 1998 0.33 0.41 0.55 0.63 1.00 1.62 ---
1999 0.36 0.45 0.56 0.58 0.88 1.62 ---
2000 0.38 0.44 0.56 0.61 0.82 0.87 1.12 2001 0.38 0.44 0.59 0.74 1.07 0.92 1.93 mean 0.15 0.33 0.41 0.52 0.67 0.89 1.23 1.28 94 36th SAW Consensus Summary
Table A2.4b. Landings at age of northern Gulf of Maine yellowtail flounder.
Landings at age (thousands) age year 1 2 3 4 5 6 7 8+ sum 1985 1 138 139 112 61 20 1 1 474 1986 0 235 116 49 8 1 0 0 409 1987 0 75 315 41 17 5 2 1 456 1988 0 115 239 119 27 5 0 0 505 1989 0 112 295 55 6 1 0 0 469 1990 0 26 472 56 3 2 0 0 559 1991 0 50 162 263 43 6 7 0 531 1992 0 72 223 130 38 1 1 0 465 1993 0 9 184 150 20 5 3 1 372 1994 0 42 344 200 74 36 11 1 708 1995 0 20 196 90 15 7 0 0 329 1996 0 7 83 93 39 2 1 0 225 1997 0 12 78 66 13 0 0 0 169 1998 0 12 106 31 8 3 0 0 160 1999 0 28 119 85 12 7 0 0 251 2000 0 62 163 70 4 0 0 0 299 2001 0 35 153 100 15 5 0 0 307 mean 0 62 199 101 24 6 2 0 393 Landed weight at age (kg) age year 1 2 3 4 5 6 7 8+
1985 0.19 0.31 0.37 0.49 0.60 0.72 1.17 1.39 1986 0.32 0.46 0.58 0.74 0.93 1.40 1987 0.31 0.41 0.56 0.67 0.86 1.10 1.25 1988 0.11 0.29 0.33 0.48 0.64 0.76 1989 0.37 0.41 0.69 0.95 1.41 1.24 1.24 1990 0.31 0.41 0.54 0.90 0.99 0.99 1.79 1991 0.34 0.37 0.54 0.76 0.95 1.07 1.53 1992 0.32 0.40 0.50 0.58 0.80 1.49 1.89 1993 0.31 0.38 0.42 0.72 0.94 1.00 1.14 1994 0.28 0.38 0.49 0.60 0.67 1.04 1.12 1995 0.32 0.34 0.40 0.60 0.80 1.18 1996 0.31 0.43 0.50 0.53 0.91 1.19 1.19 1997 0.38 0.40 0.47 0.56 0.93 1.30 1.30 1998 0.33 0.41 0.54 0.63 1.00 1.62 1999 0.35 0.42 0.58 0.58 0.85 1.62 2000 0.37 0.42 0.55 0.59 0.97 0.87 1.06 2001 0.35 0.41 0.56 0.57 0.69 1.62 mean 0.15 0.33 0.40 0.52 0.66 0.89 1.23 1.36 36th SAW Consensus Summary 95
Table A2.5a. Discard estimates for Cape Cod yellowtail flounder, by fishery.
Large-mesh Trawl Fishery observed total discards discard year half kept (mt) discard (mt) d/k landings (mt) lengths 1998 1 0.1551 0.0095 0.061 355 21.8 6 2 0.1810 0.0230 0.127 426 54.1 7 1999 1 0.0091 0.0014 0.150 282 42.3 48 2 2.2226 0.0945 0.043 564 24.0 0 2000 1 10.6743 0.4195 0.039 871 34.2 608 2 1.1785 0.0431 0.037 1079 39.4 45 2001 1 5.9789 0.6183 0.103 789 81.6 42 2 6.3832 1.6209 0.254 1311 332.8 890 Gillnet Fishery observed total discards year half kept (mt) discard (mt) d/k landings (mt) 1998 1 33.6627 0.5355 0.016 360 5.7 5101 2 1.1959 0.0290 0.024 23 0.5 159 1999 1 16.6555 0.3622 0.022 207 4.5 521 2 3.3086 0.0174 0.005 36 0.2 5 2000 1 29.5608 0.4748 0.016 295 4.7 426 2 0.1919 0.0095 0.050 32 1.6 3 2001 1 13.1767 0.1202 0.009 223 2.0 63 2 1.2431 0.0095 0.008 35 0.3 0 Small-mesh Trawl Fishery observed total discards year half effort (d) discard (mt) mt/d effort (mt) 1998 1 0.0000 0.0000 0.046
- 74 3.4 0 2 0.0000 0.0000 0.046
- 308 14.0 0 1999 1 0.0000 0.0000 0.046
- 39 1.8 0 2 0.4583 0.0209 0.046 214 9.7 0 2000 1 0.0000 0.0000 0.009
- 27 0.2 0 2 9.0417 0.0794 0.009 201 1.8 0 2001 1 0.8125 0.0123 0.015 51 0.8 0 2 1.0792 0.0014 0.001 121 0.2 0 Scallop Dredge Fishery observed total discards year half effort (d) discard (mt) mt/d effort (mt) 1998 1 0.6250 0.0302 0.048 1019 49.2 19 2 7.0833 0.5643 0.080 1379 109.8 296 1999 1 2.7917 0.0372 0.013 1092 14.6 23 2 6.7500 0.0445 0.007 1478 9.7 11 2000 1 0.0000 0.0000 0.045
- 772 34.6 0 2 0.0000 0.0000 0.045
- 1045 46.8 0 2001 1 0.2583 0.0116 0.045 284 12.7 0 2 0.0000 0.0000 0.045
- 384 17.2 0
- assumed from adjacent cell 96 36th SAW Consensus Summary
Table A2.5b. Discard estimates for the northern Gulf of Maine yellowtail flounder, by fishery.
Trawl Fishery observed observed discard year half kept discard d/k landings discards lengths 1989 1 0.097 0.010 0.103 121 12 26 2 0.029 0.005 0.186 45 8 0 1990 1 0.034 0.010 0.294 117 34 8 2 0.007 0.002 0.265 80 21 0 1991 1 0.273 0.063 0.231 152 35 10 2 0.122 0.047 0.387 86 33 0 1992 1 0.196 0.055 0.282 129 36 0 2 0.720 0.017 0.024 56 1 0 1993 1 0.036 0.002 0.050 71 4 0 2 0.681 0.082 0.120 72 9 2 1994 1 0.000 0.000 0.235 220 52 0 2 0.000 0.000 0.501 55 28 0 1995 1 0.014 0.006 0.454 70 32 5 2 0.002 0.006 2.478 26 63 14 1996 1 0.013 0.004 0.311 82 26 11 2 0.000 0.060 0.501 13 7 147 1997 1 0.003 0.001 0.185 46 9 1 2 0.000 0.000 0.501 10 5 0 1998 1 0.038 0.012 0.314 45 14 38 2 0.000 0.000 0.501 17 8 0 1999 1 0.000 0.000 0.235 69 16 0 2 0.000 0.000 0.501 23 12 0 2000 1 0.660 0.079 0.119 78 9 102 2 0.186 0.066 0.353 44 15 27 2001 1 0.158 0.039 0.247 103 25 190 2 0.206 0.041 0.199 32 6 64 36th SAW Consensus Summary 97
Table A2.5b, continued.
Shrimp Fishery observed observed discard year half effort discard d/e effort discards lengths 1989 1 11 0.017 0.002 8200 13 18 2 4 0.014 0.004 1361 5 8 1990 1 19 0.067 0.004 8647 31 83 2 2 0.003 0.002 1111 2 0 1991 1 35 0.171 0.005 7402 36 222 2 5 0.020 0.004 566 2 0 1992 1 62 0.322 0.005 7413 39 175 2 3 0.002 0.001 385 0 2 1993 1 45 0.127 0.003 5666 16 394 2 1 0.003 0.003 492 1 0 1994 1 35 0.047 0.001 4777 6 86 2 4 0.010 0.002 1213 3 70 1995 1 34 0.052 0.002 8494 13 212 2 6 0.008 0.001 1971 3 29 1996 1 13 0.020 0.002 9656 15 88 2 2 0.004 0.002 2135 4 14 1997 1 6 0.003 0.000 9648 4 9 2 0 0.000 0.002 1086 3 0 1998 1 0 0.000 0.002 6295 15 0 2 0 0.000 0.002 311 1 0 1999 1 0 0.000 0.002 3811 9 0 2 0 0.000 0.002 0 0 0 2000 1 0 0.000 0.002 3382 8 0 2 0 0.000 0.002 0 0 0 2001 1 2 0.002 0.001 2963 3 0 2 0 0.000 0.002 0 0 0 98 36th SAW Consensus Summary
Table A2.5b, continued.
Gillnet Fishery observed observed discard year half kept discard d/k landings discards lengths 1989 1 0.000 0.000 0.323 25 8 0 2 0.013 0.004 0.323 2 1 0 1990 1 0.049 0.012 0.249 29 7 0 2 0.004 0.012 2.878 1 3 0 1991 1 0.074 0.011 0.147 12 2 1 2 0.069 0.075 1.099 1 1 3 1992 1 0.968 0.095 0.098 11 1 40 2 0.065 0.026 0.403 1 0 7 1993 1 1.292 0.098 0.076 13 1 31 2 0.010 0.003 0.308 1 0 1 1994 1 0.662 0.005 0.007 44 0 4 2 0.222 0.003 0.011 2 0 1 1995 1 2.794 0.015 0.005 27 0 36 2 0.083 0.001 0.008 1 0 1 1996 1 2.775 0.004 0.001 11 0 3 2 0.055 0.001 0.026 0 0 1 1997 1 7.112 0.008 0.001 17 0 7 2 0.067 0.000 0.000 1 0 0 1998 1 0.031 0.002 0.075 11 1 0 2 0.003 0.000 0.000 0 0 0 1999 1 0.076 0.000 0.000 23 0 0 2 0.003 0.002 0.500 6 3 0 2000 1 0.267 0.000 0.000 10 0 2 2 0.002 0.000 0.000 1 0 0 2001 1 0.047 0.007 0.145 6 1 0 2 0.003 0.000 0.000 2 0 0 36th SAW Consensus Summary 99
Table A2.6a. Discards at age of Cape Cod yellowtail flounder.
Discards at age (thousands) age 1 2 3 4 5 6 1985 340 184 34 0 0 0 1986 79 1,657 75 26 0 0 1987 14 877 168 0 0 0 1988 360 1,328 177 0 0 0 1989 114 1,405 396 1 0 0 1990 81 2,047 2,501 19 0 0 1991 460 895 561 100 7 0 1992 1,688 3,543 731 29 3 0 1993 138 324 173 30 0 0 1994 60 383 279 49 4 1 1995 453 469 652 50 2 0 1996 7 397 327 94 11 0 1997 1 399 351 117 22 1 1998 56 393 420 46 11 0 1999 11 153 188 22 3 3 2000 3 81 219 76 15 4 2001 19 837 700 26 3 1 mean 228 904 468 40 5 1 Discarded weight at age (kg) age 1 2 3 4 5 6 1985 0.13 0.15 0.15 1986 0.10 0.17 0.19 0.18 1987 0.06 0.19 0.19 1988 0.12 0.15 0.20 1989 0.13 0.21 0.25 0.36 1990 0.08 0.24 0.27 0.33 1991 0.12 0.19 0.27 0.37 0.54 1992 0.05 0.11 0.22 0.31 0.36 1993 0.09 0.15 0.27 0.33 0.63 1994 0.08 0.20 0.29 0.32 0.38 0.34 1995 0.07 0.16 0.23 0.33 0.48 1996 0.04 0.15 0.28 0.36 0.50 1997 0.03 0.21 0.29 0.39 0.54 0.65 1998 0.03 0.23 0.33 0.37 0.46 0.59 1999 0.03 0.25 0.29 0.45 0.48 0.99 2000 0.03 0.29 0.38 0.57 0.61 0.80 2001 0.03 0.26 0.30 0.46 0.80 1.13 mean 0.07 0.19 0.26 0.37 0.53 0.75 100 36th SAW Consensus Summary
Table A2.6b. Discards at age of northern Gulf of Maine yellowtail flounder.
Discards at age (thousands) age 1 2 3 4 5 6 7 sum 1985 341 185 34 0 0 0 0 560 1986 16 336 15 5 0 0 0 372 1987 5 324 62 0 0 0 0 391 1988 91 336 45 0 0 0 0 472 1989 4 53 132 10 0 0 0 199 1990 3 134 236 2 0 0 0 375 1991 5 116 139 134 0 0 0 394 1992 21 26 200 58 0 0 0 305 1993 21 67 33 43 0 0 0 164 1994 15 22 7 132 53 41 30 300 1995 5 29 175 120 70 0 0 400 1996 0 38 84 92 2 0 0 216 1997 2 20 58 4 0 0 0 84 1998 52 46 92 14 3 0 0 207 1999 6 55 108 17 1 0 0 187 2000 7 58 52 12 0 0 0 130 2001 1 26 26 78 4 0 0 134 mean 35 110 88 43 8 2 2 288 Discarded weight at age (kg) age 1 2 3 4 5 6 7 1985 0.13 0.15 0.15 1986 0.10 0.17 0.19 0.18 1987 0.06 0.19 0.19 1988 0.12 0.15 0.20 1989 0.13 0.21 0.24 0.39 1990 0.09 0.20 0.29 0.41 1991 0.08 0.22 0.28 0.32 1992 0.06 0.11 0.27 0.32 1993 0.08 0.12 0.25 0.30 1994 0.09 0.12 0.18 0.27 0.31 0.36 0.54 1995 0.04 0.14 0.25 0.32 0.34 1996 0.10 0.25 0.28 0.43 1997 0.12 0.09 0.30 0.35 1998 0.06 0.15 0.26 0.31 0.27 1999 0.19 0.13 0.24 0.32 0.49 2000 0.06 0.14 0.33 0.49 0.30 2001 0.07 0.19 0.23 0.29 0.37 mean 0.09 0.15 0.24 0.33 0.36 0.36 0.54 36th SAW Consensus Summary 101
Table A2.7a. Indices of Cape Cod - Gulf of Maine yellowtail flounder abundance at age and biomass.
MADMF Spring Survey age 1 2 3 4 5 6 7 8+ sum kg/tow 1978 2.71 20.69 11.82 1.60 0.63 0.54 0.10 0.13 38.22 10.16 1979 2.63 22.58 13.85 3.68 0.86 0.00 0.17 0.00 43.77 11.38 1980 2.68 17.62 10.10 2.30 0.15 0.00 0.00 0.00 32.85 10.03 1981 5.61 58.83 9.00 2.26 1.59 0.27 0.00 0.00 77.56 16.35 1982 0.69 17.06 17.04 4.45 0.94 0.06 0.04 0.00 40.28 12.85 1983 3.13 8.50 11.51 4.28 0.04 0.17 0.03 0.00 27.66 9.00 1984 0.43 18.13 7.56 2.29 0.85 0.00 0.00 0.00 29.26 7.37 1985 1.97 8.27 7.15 1.52 0.59 0.39 0.05 0.05 19.99 5.21 1986 1.73 15.39 1.74 0.24 0.21 0.04 0.00 0.00 19.36 4.52 1987 2.53 4.95 5.31 0.97 0.27 0.11 0.08 0.00 14.22 3.67 1988 3.10 14.46 2.52 0.60 0.05 0.02 0.00 0.00 20.74 3.83 1989 0.67 22.26 3.18 1.08 0.06 0.00 0.00 0.00 27.25 4.73 1990 0.63 11.77 15.57 0.63 0.14 0.01 0.02 0.01 28.77 6.60 1991 0.06 5.34 3.31 2.15 0.48 0.12 0.05 0.00 11.50 3.32 1992 1.30 11.03 9.71 2.38 1.45 0.03 0.03 0.00 25.94 6.54 1993 0.63 7.99 6.31 1.94 0.23 0.06 0.20 0.03 17.38 4.60 1994 2.67 24.02 7.53 1.49 0.33 0.12 0.00 0.00 36.15 6.23 1995 7.51 14.64 24.96 2.88 1.20 0.02 0.02 0.00 51.22 10.38 1996 1.17 18.03 14.70 6.78 1.74 0.00 0.04 0.00 42.46 9.25 1997 0.52 16.94 12.22 4.04 0.54 0.00 0.00 0.00 34.26 7.55 1998 0.55 4.96 13.50 1.25 0.19 0.02 0.00 0.00 20.46 5.17 1999 0.10 6.34 10.90 1.28 0.08 0.00 0.00 0.00 18.70 5.08 2000 0.83 21.92 33.29 11.28 1.30 0.52 0.00 0.00 69.14 20.37 2001 0.22 10.21 38.20 10.39 1.68 0.00 0.00 0.00 60.71 19.34 2002 0.36 1.29 13.84 5.34 0.26 0.17 0.00 0.00 21.27 7.43 mean 1.78 15.33 12.19 3.08 0.63 0.11 0.03 0.01 33.16 8.44 102 36th SAW Consensus Summary
Table A2.7b.
MADMF Fall Survey age 0 1 2 3 4 5 6 7 8+ sum kg/tow 1978 0.04 7.13 7.74 1.45 0.11 0.00 0.01 0.00 0.00 16.48 2.80 1979 0.03 24.11 22.82 1.78 0.06 0.00 0.00 0.00 0.00 48.80 7.33 1980 0.03 26.54 12.38 2.70 0.35 0.00 0.00 0.00 0.00 42.00 5.90 1981 0.00 2.93 6.54 1.54 0.23 0.17 0.00 0.00 0.00 11.41 2.76 1982 0.00 9.58 3.36 5.54 0.30 0.08 0.00 0.00 0.00 18.86 4.20 1983 0.00 9.68 6.68 1.60 0.13 0.00 0.00 0.00 0.00 18.09 3.39 1984 0.04 1.91 3.00 0.86 0.39 0.10 0.02 0.00 0.04 6.37 1.18 1985 0.04 5.70 1.63 1.03 0.00 0.00 0.00 0.00 0.02 8.42 1.17 1986 0.01 2.60 4.95 0.20 0.03 0.01 0.00 0.00 0.00 7.80 1.36 1987 0.44 5.85 2.30 0.49 0.07 0.02 0.00 0.00 0.00 9.17 1.09 1988 0.00 8.96 11.24 2.27 0.15 0.00 0.00 0.00 0.00 22.62 3.71 1989 0.00 2.64 5.22 0.96 0.10 0.00 0.00 0.00 0.00 8.92 1.52 1990 0.00 5.20 11.93 4.84 0.01 0.00 0.00 0.00 0.00 21.98 4.16 1991 0.00 3.76 5.14 5.03 0.86 0.00 0.00 0.00 0.00 14.78 3.23 1992 0.20 7.18 3.62 2.08 0.47 0.20 0.00 0.00 0.00 13.75 2.00 1993 0.00 8.39 7.29 5.80 1.43 0.00 0.00 0.00 0.00 22.91 3.99 1994 0.00 2.36 11.79 1.79 0.15 0.00 0.00 0.00 0.00 16.09 3.27 1995 0.00 8.38 15.16 5.85 0.00 0.00 0.00 0.00 0.00 29.40 5.75 1996 0.01 1.87 3.94 2.18 0.17 0.00 0.00 0.00 0.00 8.17 1.56 1997 0.00 1.01 7.38 1.14 0.16 0.10 0.00 0.00 0.00 9.79 2.10 1998 0.00 7.05 6.74 2.25 0.00 0.00 0.00 0.00 0.00 16.05 2.68 1999 0.15 4.73 11.94 4.10 0.65 0.08 0.00 0.00 0.00 21.66 4.71 2000 0.00 1.36 8.25 3.53 0.22 0.10 0.00 0.03 0.00 13.48 3.46 2001 0.00 0.57 8.06 4.23 0.14 0.00 0.00 0.00 0.00 13.00 3.55 mean 0.04 6.65 7.88 2.63 0.26 0.04 0.00 0.00 0.00 17.50 3.20 36th SAW Consensus Summary 103
Table A2.7c.
NMFS Spring Survey year 1 2 3 4 5 6 7 8+ sum kg/tow 1977 0.775 0.329 0.185 0.049 0.093 0.000 0.000 0.000 1.431 0.566 1978 0.000 0.057 0.247 0.036 0.088 0.000 0.000 0.000 0.427 0.209 1979 0.228 0.315 0.748 0.770 0.068 0.021 0.000 0.019 2.169 0.795 1980 0.000 4.150 2.189 0.828 0.167 0.000 0.000 0.000 7.334 2.426 1981 0.041 2.921 2.198 1.143 0.584 0.473 0.179 0.000 7.538 2.468 1982 0.016 1.195 3.009 1.519 0.416 0.232 0.219 0.099 6.705 2.814 1983 1.190 3.203 2.093 1.298 0.092 0.064 0.000 0.000 7.939 2.340 1984 0.039 1.020 0.606 0.394 0.257 0.023 0.032 0.069 2.440 0.809 1985 0.047 0.806 0.865 0.205 0.123 0.043 0.000 0.000 2.089 0.615 1986 0.024 1.786 0.198 0.137 0.100 0.000 0.000 0.000 2.245 0.470 1987 0.062 1.599 2.356 0.637 0.538 0.570 0.611 0.304 6.676 2.971 1988 0.896 3.781 0.922 0.513 0.268 0.097 0.057 0.000 6.533 1.077 1989 0.177 2.179 1.442 0.372 0.274 0.038 0.038 0.038 4.559 0.863 1990 2.285 6.144 0.210 0.000 0.099 0.000 0.000 0.000 8.739 1.948 1991 0.421 3.554 2.834 1.049 0.222 0.000 0.047 0.000 8.128 1.783 1992 0.155 0.915 1.835 0.498 0.018 0.000 0.000 0.000 3.421 0.764 1993 0.064 0.656 1.045 0.563 0.000 0.000 0.000 0.000 2.327 0.501 1994 0.347 2.631 1.578 0.951 0.593 0.208 0.000 0.000 6.308 1.201 1995 0.182 1.040 3.978 2.991 0.432 0.048 0.000 0.000 8.670 2.036 1996 0.015 0.547 1.430 2.009 0.335 0.000 0.000 0.000 4.336 1.108 1997 0.021 0.934 2.025 1.545 0.288 0.000 0.000 0.000 4.813 1.311 1998 0.000 0.748 2.934 0.887 0.144 0.000 0.000 0.000 4.712 1.155 1999 0.018 0.848 3.633 1.853 0.332 0.147 0.000 0.000 6.831 1.977 2000 0.238 3.931 17.630 5.837 0.953 0.715 0.000 0.000 29.305 9.506 2001 0.000 1.201 4.878 1.030 0.216 0.000 0.000 0.000 7.324 2.292 2002 0.015 1.568 7.092 3.271 0.213 0.026 0.000 0.026 12.211 4.554 average 0.279 1.848 2.622 1.169 0.266 0.104 0.046 0.021 6.354 1.868 104 36th SAW Consensus Summary
Table A2.7d.
NMFS Fall Survey year 1 2 3 4 5 6 7 8+sum kg/tow 1977 4.882 9.330 4.987 0.788 0.197 0.053 0.062 0.123 20.421 7.526 1978 0.354 3.540 2.383 0.152 0.168 0.015 0.015 0.015 6.642 2.047 1979 4.003 4.072 1.227 0.306 0.075 0.016 0.000 0.000 9.698 2.596 1980 10.534 8.937 4.115 1.556 0.340 0.000 0.037 0.000 25.518 6.557 1981 1.596 4.965 1.330 0.532 0.266 0.177 0.000 0.000 8.866 1.881 1982 0.572 2.743 2.593 0.313 0.379 0.000 0.000 0.000 6.599 2.056 1983 0.285 0.546 0.312 0.020 0.000 0.000 0.000 0.000 1.162 0.264 1984 0.320 1.124 0.443 0.763 0.546 0.151 0.075 0.075 3.497 1.380 1985 4.609 1.778 1.352 0.068 0.068 0.068 0.000 0.000 7.943 1.583 1986 1.308 3.613 0.297 0.019 0.019 0.000 0.000 0.000 5.257 0.970 1987 0.564 1.357 0.476 0.057 0.049 0.000 0.000 0.000 2.503 0.556 1988 3.128 4.587 0.443 0.134 0.000 0.000 0.000 0.000 8.292 1.126 1989 1.657 5.338 2.008 0.417 0.146 0.066 0.000 0.000 9.631 2.202 1990 3.500 6.201 2.874 0.046 0.010 0.000 0.000 0.000 12.630 2.345 1991 1.840 1.643 1.639 0.332 0.000 0.000 0.000 0.000 5.453 1.202 1992 2.537 2.758 1.878 0.948 0.183 0.142 0.000 0.000 8.447 1.932 1993 4.445 4.507 0.601 0.099 0.000 0.000 0.000 0.000 9.652 1.106 1994 2.472 7.368 2.596 0.824 0.354 0.000 0.000 0.000 13.615 2.701 1995 0.516 0.713 1.068 0.297 0.171 0.000 0.000 0.000 2.765 0.783 1996 1.058 2.907 4.928 1.179 0.133 0.000 0.000 0.000 10.205 2.614 1997 1.049 2.440 2.945 1.223 0.670 0.115 0.000 0.000 8.441 2.277 1998 1.022 2.984 1.197 0.986 0.234 0.000 0.000 0.000 6.422 1.637 1999 4.147 8.090 5.532 1.697 0.698 0.027 0.000 0.000 20.191 5.983 2000 0.955 6.729 4.455 0.260 0.000 0.000 0.000 0.000 12.399 3.472 2001 0.117 3.835 2.231 0.114 0.019 0.000 0.000 0.000 6.316 1.889 average 2.299 4.084 2.156 0.525 0.189 0.033 0.008 0.009 9.303 2.347 36th SAW Consensus Summary 105
Table A2.8. Correlation among indices of abundance at age for Cape Cod - Gulf of Maine yellowtail flounder.
Age-1 MASS_F MASS_S NMFS_S MASS_F 1.00 MASS_S 0.07 1.00 NMFS_S 0.48 -0.10 1.00 Age-2 MASS_F MASS_S NMFS_F NMFS_S MASS_F 1.00 MASS_S 0.33 1.00 NMFS_F 0.17 0.59 1.00 NMFS_S 0.16 0.59 0.63 1.00 Age-3 MASS_F MASS_S NMFS_F NMFS_S MASS_F 1.00 MASS_S 0.45 1.00 NMFS_F 0.58 0.37 1.00 NMFS_S 0.64 0.45 0.54 1.00 Age-4 MASS_F MASS_S NMFS_F NMFS_S MASS_F 1.00 MASS_S 0.56 1.00 NMFS_F 0.69 0.56 1.00 NMFS_S 0.43 0.48 0.63 1.00 Age-5 MASS_F MASS_S NMFS_F NMFS_S MASS_F 1.00 MASS_S 0.00 1.00 NMFS_F -0.04 0.28 1.00 NMFS_S -0.08 0.50 0.24 1.00 Age-6+ MASS_F MASS_S NMFS_F NMFS_S MASS_F 1.00 MASS_S 0.10 1.00 NMFS_F -0.01 0.04 1.00 NMFS_S -0.44 0.52 0.27 1.00 106 36th SAW Consensus Summary
Table A2.9. Results of virtual population analysis of Cape Cod - Gulf of Maine yellowtail flounder.
Abundance (thousands) age-1 age-2 age-3 age-4 age-5+ sum 1985 12302 3195 1696 1168 814 19175 1986 6030 9451 1489 568 88 17626 1987 8083 4851 3915 509 273 17631 1988 28844 6601 2266 1096 345 39152 1989 11325 23207 3068 495 75 38170 1990 11634 9166 16922 872 111 38705 1991 13071 9449 4883 5349 1008 33760 1992 9639 10281 6495 2401 668 29484 1993 10404 6346 4817 3543 731 25841 1994 7177 8375 4811 2972 1710 25045 1995 6380 5808 6372 2443 745 21748 1996 9625 4809 4076 2725 898 22133 1997 8590 7874 3402 1896 442 22204 1998 10724 7031 5621 1361 504 25241 1999 13439 8682 5117 2522 575 30335 2000 10047 10988 6598 2788 411 30832 2001 1939 8218 7961 2634 447 21199 2002 --- 1569 5185 3069 1188 ---
average 10544 8106 5261 2134 613 26958 Fishing Mortality age-1 age-2 age-3 age-4 age-5+ age 3-4 1985 0.06 0.56 0.89 0.92 0.92 0.90 1986 0.02 0.68 0.87 0.90 0.90 0.88 1987 0.00 0.56 1.07 1.11 1.11 1.07 1988 0.02 0.57 1.32 1.39 1.39 1.34 1989 0.01 0.12 1.06 1.09 1.09 1.06 1990 0.01 0.43 0.95 0.98 0.98 0.95 1991 0.04 0.17 0.51 0.52 0.52 0.52 1992 0.22 0.56 0.41 0.41 0.41 0.41 1993 0.02 0.08 0.28 0.28 0.28 0.28 1994 0.01 0.07 0.48 0.48 0.48 0.48 1995 0.08 0.15 0.65 0.66 0.66 0.65 1996 0.00 0.15 0.57 0.57 0.57 0.57 1997 0.00 0.14 0.72 0.73 0.73 0.72 1998 0.01 0.12 0.60 0.61 0.61 0.60 1999 0.00 0.07 0.41 0.41 0.41 0.41 2000 0.00 0.12 0.72 0.73 0.73 0.72 2001 0.01 0.26 0.75 0.75 0.75 0.75 average 0.03 0.28 0.72 0.74 0.74 0.73 36th SAW Consensus Summary 107
Table A2.9 continued.
Spawning Stock Biomass (mt) age-1 age-2 age-3 age-4 age-5+ sum 1985 0 50 313 359 332 1055 1986 0 131 332 191 43 696 1987 0 65 728 162 115 1070 1988 0 81 331 294 128 834 1989 0 439 559 188 44 1230 1990 0 141 3138 293 60 3633 1991 0 155 1000 2063 591 3810 1992 0 78 1308 931 331 2648 1993 0 72 1149 1216 490 2926 1994 0 132 1087 1028 836 3083 1995 0 88 1159 700 312 2260 1996 0 63 912 928 364 2267 1997 0 164 715 592 177 1647 1998 0 128 1272 514 255 2169 1999 0 192 1319 1095 303 2909 2000 0 277 1567 1058 184 3087 2001 0 174 1777 992 234 3177 average 0 143 1098 741 282 2265 108 36th SAW Consensus Summary
Table A2.10. Yield and biomass per recruit of Cape Cod - Gulf of Maine yellowtail flounder.
The NEFC Yield and Stock Size per Recruit Program - PDBYPRC PC Ver.1.2 [Method of Thompson and Bell (1934)] 1-Jan-1992 Run Date: 4-12-2002; Time: 14:49:47.35 CC_GOM YELLOWTAIL FLOUNDER - 1994-2001 INPUT Proportion of F before spawning: .4167 Proportion of M before spawning: .4167 Natural Mortality is Constant at: .200 Initial age is: 1; Last age is: 8 Last age is a PLUS group; Original age-specific PRs, Mats, and Mean Wts from file:
==> CCGOMYT.DAT Age-specific Input data for Yield per Recruit Analysis Age l Fish Mort Nat Mort l Proportion l Average Weights l Pattern Pattern l Mature l Catch Stock 1 l .0200 1.0000 l .0000 l .043 .043 2 l .2200 1.0000 l .0800 l .273 .273 3 l .9800 1.0000 l .8100 l .387 .387 4 l 1.0000 1.0000 l 1.0000 l .501 .501 5 l 1.0000 1.0000 l 1.0000 l .588 .588 6 l 1.0000 1.0000 l 1.0000 l .845 .845 7 l 1.0000 1.0000 l 1.0000 l 1.176 1.176 8+ l 1.0000 1.0000 l 1.0000 l 1.328 1.328 Summary of Yield per Recruit Analysis for:
CC_GOM YELLOWTAIL FLOUNDER - 1994-2001 INPUT Slope of the Yield/Recruit Curve at F=0.00: --> 3.0044 F level at slope=1/10 of the above slope (F0.1): -----> .195 Yield/Recruit corresponding to F0.1: -----> .2205 F level to produce Maximum Yield/Recruit (Fmax): -----> .437 Yield/Recruit corresponding to Fmax: -----> .2432 F level at 40 % of Max Spawning Potential (F40): -----> .174 SSB/Recruit corresponding to F40: --------> 1.1917 36th SAW Consensus Summary 109
Table A2.10 cont.
FMORT TOTCTHN TOTCTHW TOTSTKN TOTSTKW SPNSTKN SPNSTKW % MSP
.000 .00000 .00000 5.5167 3.5367 3.3453 2.9798 100.00
.100 .23532 .16955 4.3458 2.1815 2.1818 1.6643 55.85 F0.1 .195 .34935 .22052 3.7809 1.5853 1.6236 1.0959 36.78 F40% .174 .32915 .21343 3.8808 1.6866 1.7221 1.1917 39.99
.200 .35385 .22197 3.7586 1.5630 1.6017 1.0748 36.07
.300 .42566 .23872 3.4049 1.2250 1.2549 .7584 25.45
.400 .47407 .24300 3.1678 1.0191 1.0246 .5688 19.09 Fmax .437 .48838 .24322 3.0981 .9623 .9573 .5172 17.36
.500 .50912 .24277 2.9975 .8838 .8607 .4462 14.97
.600 .53579 .24102 2.8687 .7896 .7383 .3622 12.15
.700 .55687 .23890 2.7677 .7210 .6436 .3018 10.13
.800 .57404 .23682 2.6861 .6691 .5682 .2567 8.62
.900 .58834 .23493 2.6186 .6286 .5067 .2221 7.45 1.000 .60050 .23325 2.5617 .5962 .4557 .1947 6.53 1.100 .61099 .23175 2.5128 .5696 .4128 .1725 5.79 1.200 .62018 .23041 2.4704 .5473 .3762 .1543 5.18 1.300 .62832 .22919 2.4330 .5284 .3446 .1390 4.67 1.400 .63560 .22807 2.3998 .5120 .3171 .1261 4.23 1.500 .64217 .22702 2.3699 .4977 .2929 .1150 3.86 1.600 .64814 .22604 2.3429 .4851 .2715 .1054 3.54 1.700 .65361 .22511 2.3182 .4738 .2525 .0970 3.25 1.800 .65865 .22422 2.2956 .4636 .2355 .0895 3.00 1.900 .66332 .22337 2.2746 .4544 .2201 .0830 2.78 2.000 .66766 .22254 2.2552 .4459 .2063 .0771 2.59 110 36th SAW Consensus Summary
Figure A2.1. Statistical areas for Cape Cod - Gulf of Maine yellowtail flounder.
36th SAW Consensus Summary 111
Figure A2.2. Cape Cod - Gulf of Maine yellowtail flounder catch.
7000 CC landings CC discards GOM landings GOM discards 6000 5000 4000 Catch (mt) 3000 2000 1000 0
19 19 19 19 19 1935 39 43 47 51 19 19 19 19 1955 59 63 67 71 75 19 19 19 19 19 1979 83 87 91 95 99 112 36th SAW Consensus Summary
Figure A2.3. Total catch at age of Cape Cod - Gulf of Maine yellowtail flounder.
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002 0 1 2 3 4 5 6 7 8 Age 36th SAW Consensus Summary 113
Figure A2.4. Mean weight at age of Cape Cod - Gulf of Maine yellowtail flounder catch.
1.4 1.2 Age-6 1.0 Mean Weight (kg) 0.8 Age 5 0.6 Age-4 0.4 Age-3 Age-2 0.2 Age-1 0.0 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 114 36th SAW Consensus Summary
Figure A2.5. NEFSC survey strata used for Cape Cod - Gulf of Maine yellowtail flounder.
36th SAW Consensus Summary 115
Figure A2.6a. Survey indices of Cape Cod - Gulf of Maine yellowtail flounder biomass.
MAD MF S pring Survey 30 k g/tow
+ 2S E
-2S E 25 Survey Biom as s (kg/tow )
20 15 10 5
0 78 80 82 84 86 88 90 92 94 96 98 00 02 19 19 19 19 19 19 19 19 19 19 19 20 20 MAD MF Fall Survey 10 k g/tow
+ 2S E 9
-2S E 8
Surve y Biom a ss (kg/tow )
7 6
5 4
3 2
1 0
78 80 82 84 86 88 90 92 94 96 98 00 19 19 19 19 19 19 19 19 19 19 19 20 116 36th SAW Consensus Summary
Survey Biom a ss (k g/tow ) S urve y Biom a ss (kg/tow )
19 0 2 4 6 8 10 12 14 19 0 2 4 6 8 10 12 14 16 18 77 77 Figure A2.6b.
19 19 79 79 19 19 -2S E + 2S E 81 k g/tow 81 19 19 83 83 36th SAW Consensus Summary 19 19 85 85 19 19 87 87 19 19 89 89 19 19 91 N MFS Fall S urvey 91 N MFS S pring Survey 19 19 93 93 19 19 95 95 19 19 97 97 19 19 99 99 20 20 01 01
-2S E + 2S E k g/tow 117
Figure A2.7a. Distribution of yellowtail flounder from recent surveys.
118 36th SAW Consensus Summary
Figure A2.7b.
36th SAW Consensus Summary 119
Figure A2.8. Geographic distribution of area-swept biomass of Cape Cod - Gulf of Maine yellowtail flounder from the NEFSC fall survey (offshore strata only).
2000 1800 1600 Cape Cod 1400 Gulf of Maine Survey Biomass 1200 1000 800 600 400 200 0
63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 01 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 120 36th SAW Consensus Summary
Figure A2.9a. Survey age distributions of Cape Cod - Gulf of Maine yellowtail flounder.
MADMF Spring Survey
-1976
-1978
-1980
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004 0 1 2 3 4 5 6 7 8 Age 36th SAW Consensus Summary 121
Figure A2.9b.
MADMF Fall Survey
-1976
-1978
-1980
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004
-1 0 1 2 3 4 5 6 7 Age 122 36th SAW Consensus Summary
Figure A2.9c.
NMFS Spring Survey
-1976
-1978
-1980
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004 0 1 2 3 4 5 6 7 8 Age 36th SAW Consensus Summary 123
Figure A2.9d.
NMFS Fall Survey
-1972
-1974
-1976
-1978
-1980
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004 0 1 2 3 4 5 6 7 8 Age 124 36th SAW Consensus Summary
Figure A2.10. Normalized indices of abundance of Cape Cod - Gulf of Maine yellowtail flounder.
M A S S _F A ge-1 A ge-2 M A S S _F M A S S _S M A S S _S 3 NM FS _F NM FS _S NM FS _S 1.5 1
2 0.5 1
0
- 0.5 0
-1
-1
- 1.5
-2 -2
- 2.5
-3
-3
-4 - 3.5 A ge-3 M A S S _F M A S S _S A ge-4 M A S S _F M A S S _S NM FS _F NM FS _S NM FS _F NM FS _S 2 2 1.5 1.5 1
1 0.5 0.5 0 0
- 0.5 - 0.5
-1
-1
- 1.5
- 1.5
-2 -2
- 2.5
- 2.5
-3
-3 A ge-5 M A S S _F M A S S _S A ge-6+ M A S S _F M A S S _S NM FS _F NM FS _S NM FS _F NM FS _S 2 2
1 1 0
0
-1
-1
-2
-2
-3
-3
-4
-4
-5 36th SAW Consensus Summary 125
Figure A2.11. Residuals of the Cape Cod - Gulf of Maine yellowtail flounder ADAPT calibration.
Age-1 MASS_S Age-2 MASS_F MASS_S NMFS_F NMFS_S 4 4 3 3 2 2 1 1 E 0 E 0
-1 -1
-2 -2
-3 -3
-4 -4 19 19 19 19 19 19 19 19 20 85 87 89 91 93 95 97 99 01 85 87 89 91 93 95 97 99 01 19 19 19 19 19 19 19 19 20 Age-3 Age-4 MASS_F MASS_S NMFS_F NMFS_S MASS_F MASS_S NMFS_F NMFS_S 6 5 4
4 3
2 2 0 1 E E
-2 0
-1
-4
-2
-6
-3
-8 -4 19 19 19 19 19 19 19 19 20 19 19 19 19 19 19 19 19 20 85 87 89 91 93 95 97 99 01 85 87 89 91 93 95 97 99 01 Age-5 MASS_F MASS_S NMFS_F NMFS_S 10 8
6 4
2 E 0
-2
-4
-6
-8
-10 19 19 19 19 19 19 19 19 20 85 87 89 91 93 95 97 99 01 126 36th SAW Consensus Summary
SSB (mt)
Fishing Mortality (3-4 wtd) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 19 0 500 1000 1500 2000 2500 3000 3500 4000 4500 19 84 84 19 19 85 85 19 19 86 86 19 19 87 87 19 19 88 88 19 19 89 89 36th SAW Consensus Summary 19 19 90 90 19 19 91 91 19 19 92 92 19 19 93 93 19 19 94 94 19 19 95 95 19 19 Figure A2.12. Results of the Cape Cod - Gulf of Maine VPA.
96 96 SSB Year; Recruitment Yearclass 19 19 97 97 19 19 98 98 19 19 99 99 20 20 00 00 20 20 01 01 0 5 10 15 20 25 30 35 127 Age-1 Abundance (mil.)
Figure A2.12b. Stock and recruitment of Cape Cod - Gulf of Maine yellowtail flounder (extreme points labeled by yearclass).
35 30 1987 25 Age-1 Recruits (mil) 20 15 1990 10 1985 5
2000 0
0 500 1000 1500 2000 2500 3000 3500 4000 4500 Spawning Biomass (mt) 128 36th SAW Consensus Summary
Figure A2.12c. Abundance at age of Cape Cod - Gulf of Maine yellowtail flounder.
-1982
-1984
-1986
-1988
-1990
-1992
-1994
-1996
-1998
-2000
-2002
-2004 0 1 2 3 4 5 Age 36th SAW Consensus Summary 129
Figure A2.13. Retrospective analysis of the Cape Cod - Gulf of Maine yellowtail flounder VPA.
1.6 1.4 1.2 Fis hin g M o r tality (3-4) 1.0 0.8 0.6 0.4 0.2 0.0 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 4500 4000 3500 Spaw n in g Biom as s (m t) 3000 2500 2000 1500 1000 500 0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 30000 25000 A ge -1 Re cr u itm e n t (m illio n s )
20000 15000 10000 5000 0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 130 36th SAW Consensus Summary
Figure A2.14. Yield and spawning biomass per recruit of Cape Cod - Gulf of Maine yellowtail flounder.
0.25 3.0 2.5 0.20 Yield per Recruit (kg) SSB per Recruit (kg) 2.0 0.15 YPR SPR 1.5 0.10 1.0 0.05 0.5 F40%
0.00 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 36th SAW Consensus Summary 131
Figure A2.15. Observed and expected age distribution of spawning biomass at F40% for Cape Cod-Gulf of Maine yellowtail flounder.
0.60 1992-1999 0.50 Percent of Total SSB 0.40 0.30 0.20 0.10 0.00 1 2 3 4 5+
0.60 2000 0.50 Percent of Total SSB 0.40 0.30 0.20 0.10 0.00 1 2 3 4 5+
0.60 2001 0.50 Percent of Total SSB 0.40 0.30 0.20 0.10 0.00 1 2 3 4 5+
0.60 Long term at Fmsy 0.50 Percent of Total SSB 0.40 0.30 0.20 0.10 0.00 1 2 3 4 5+
132 36th SAW Consensus Summary
Figure A2.16. Stochastic projection of Cape Cod- Gulf of Maine yellowtail flounder spawning biomass (upper panel) and landings (lower panel) at 2002 F = 0.64 and 2003-2009 F=0.03; dotted lines indicate 90% confidence limits and the horizontal dashed line indicates SSBMSY).
18 16 14 12 SSB (kt) 10 8
6 4
2 0
2002 2003 2004 2005 2006 2007 2008 2009 2.5 2.0 1.5 Landings (kt) 1.0 0.5 0.0 2002 2003 2004 2005 2006 2007 2008 2009 36th SAW Consensus Summary 133
Figure A2.17. Length distribution of Cape Cod - Gulf of Maine yellowtail flounder by decade, from offshore survey strata 25, 27, 39 and 40.
0.18 1960s 0.16 0.14 Re lative Fr e que ncy 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.18 Le n gth (cm )
1970s 0.16 0.14 Re lative Fr e qu e ncy 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 1980s L e ng th (cm )
0.18 0.16 Re lative Fr e q ue n cy 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.18 1990s 0.16 L e ng th (cm )
0.14 Re lative Fr e q ue n cy 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.18 2000-2001 L e ng th (cm )
0.16 0.14 Re lative Fr e qu e ncy 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 Le ngth (cm )
134 36th SAW Consensus Summary
Figure A2.18a. Length distribution of Cape Cod - Gulf of Maine yellowtail flounder by decade, from the Massachusetts spring survey.
0.15 S P R IN G 1 9 7 8 - 1 9 7 9 0.12 REL ATIVE FR EQ UEN CY 0.09 0.06 0.03
- 00. .0105 2 4 6 8 10 12 S P R IN G 1 9 8 0 ' s 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 L E N G T H (C M )
0.12 R ELA TIV E FREQ U ENC Y 0.09 0.06 0.03
- 00. .1050 2 4 6 8 10 S P R IN G 1 9 9 0 ' s 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 L E N G T H (C M )
0.12 REL ATIVE FR EQ UEN CY 0.09 0.06 0.03
- 00. .0105 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 S P R IN G 2 0 0 0 - 2 0 0 2 L E N G T H (C M )
0.12 R ELA TIVE FREQU ENC Y 0.09 0.06 0.03 0.00 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 L E N G T H (C M )
36th SAW Consensus Summary 135
Figure A2.18b. Length distribution of Cape Cod - Gulf of Maine yellowtail flounder by decade, from the Massachusetts fall survey.
0.15 A U T U M N 1 9 7 8 -1 9 7 9 0.12 REL ATIVE FR EQ UEN CY 0.09 0.06 0.03 0
0 .. 0 105 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 A U T U M N 1 9 8 0 'S L E N G T H (C M )
0.12 REL AT IVE FR EQ UEN CY 0.09 0.06 0.03 0
0 .. 0 105 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 A U T U M N 1 9 9 0 'S L E N G T H (C M )
0.12 REL ATIVE FR EQ UEN CY 0.09 0.06 0.03 0.15 0.00 A U T U M N 2 0 0 0 -2 0 0 1 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 L E N G T H (C M )
0.12 REL ATIVE FR EQ UEN CY 0.09 0.06 0.03 0.00 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 L E N G T H (C M )
136 36th SAW Consensus Summary
Figure A2.19. Size distribution of yellowtail flounder sampled from the inshore Gulf of Maine (NEFSC summer surveys, 1978-1981).
Inshore Gulf of Maine 0.18 0.16 0.14 Relative Frequency 0.12 0.10 0.08 0.06 0.04 0.02 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 Length (cm) 36th SAW Consensus Summary 137
Figure A2.20. Size distribution of yellowtail flounder sampled from the NEFSC survey in the central and eastern Gulf of Maine, by decade.
0.10 1960s 0.09 0.08 Re lative Fr e q u e n cy 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.10 L e n g th (cm )
1970s 0.09 0.08 Re lative Fr e q u e n cy 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.10 L e n g th (cm )
1980s 0.09 0.08 Re lative Fr e q u e n cy 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.10 L e n g th (cm )
1990s 0.09 0.08 Re lative Fr e q u e n cy 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 0.10 L e n g th (cm )
2000-2001 0.09 0.08 Re lative Fr e q u e n cy 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 L e n g th (cm )
138 36th SAW Consensus Summary
B1. SOUTHERN NEW ENGLAND/MID-ATLANTIC (SNE/MA) WINTER FLOUNDER TERMS OF REFERENCE The following terms of reference were addressed for the Southern New England/Mid Atlantic (SNE/MA) stock complex of winter flounder:
- 1) Update the status of SNE/MA winter flounder stock through 2001 providing estimates of fully recruited fishing mortality rate, biomass weighted fishing mortality rate, stock size, mean biomass, spawning stock biomass, and recruitment as appropriate. Characterize uncertainty in SSB and fishing mortality rates.
- 2) Provide short-term (2003) and medium term projections (2009) of catch and biomass (mean biomass, SSB) under status quo F, and ASMFCs F40% target, and NEFMCs FMSY.
- 3) Develop research recommendations for improving the assessment of SNE/MA winter flounder.
- 4) Comment on and revise, where necessary, the ASMFC and the NEFMC overfishing definitions for this stock. (Note: Currently ASMFC and the NEFMC have different overfishing definitions. The ASMFC Board had recommended that the Winter Flounder Technical Committee develop a single overfishing definition for this stock).
INTRODUCTION The current assessment of the SNE/MA stock complex of winter flounder is an update of the previous assessment completed in 1998 at SARC 28 (NEFSC 1999). The SARC 28 assessment included catch through 1997, research survey abundance indices through 1998, catch at age analyzed by Virtual Population Analysis (VPA) for 1981-1997, and biological reference points based on a production model conditioned on VPA results. The SARC 28 assessment concluded that the stock complex was fully exploited and at a medium level of biomass. Total biomass in 1997 was estimated to be 17,900 mt, spawning stock biomass was estimated to be 8,600 mt, and the fully recruited fishing mortality rate was estimated to be F = 0.31. Subsequent to the SARC 28 assessment, the status of SNE/MA winter flounder has been evaluated annually by projection methods to provide advice to the New England Fishery Management Council (NEFMC). The last such status update was provided in 2001, and projected total biomass to be 25,300 mt, spawning stock biomass to be 13,800 mt, and fully recruited F = 0.29, in 1999 (NEFSC 2001).
The current assessment updates landings and discard estimates, research survey abundance indices, and assessment models through 2001-2002, as applicable.
36th SAW Consensus Summary 139
Winter flounder (Pleuronectes americanus) is a demersal flatfish species commonly found in estuaries and on the continental shelf. The species is distributed between the Gulf of St.
Lawrence and North Carolina, although it is not abundant south of Delaware Bay. Within the SNE/MA stock complex, winter flounder undergo migrations from estuaries, where spawning occurs in the late winter and spring, to offshore shelf areas of less than 60 fathoms. Winter flounder reach a maximum size of around 2.25 kg (5 pounds) and 65 cm, with the exception of Georges Bank where growth rate is higher and fish may reach a maximum weight up to 3.6 kg (8 pounds; Bigelow and Schroeder 1953).
Current fishery management is coordinated by the Atlantic States Marine Fisheries Commission (ASMFC) in state waters and the NEFMC in federal waters. Winter flounder fisheries in state waters have been managed by Interstate Agreement under the auspices of the ASMFC Fishery Management Plan (FMP) for Inshore Stocks of Winter Flounder since approval in May, 1992.
The plan includes states from Delaware to Maine, with Delaware granted de minimus status (habitat regulations applicable but fishery management not required). The Plan's goal is to rebuild spawning stock abundance and achieve a fishing mortality-based management target of F40% (fishing rate that preserves 40% of the maximum spawning potential of the stock) in three steps: F25% in 1993-1994, F30% in 1995-1998, and F40% in 1999 and later years through implementation of compatible, state-specific regulations. Coastal states from New Jersey to New Hampshire have promulgated a broad suite of indirect catch and effort controls. State agencies have set or increased minimum size limits for recreationally and commercially landed flounder (10-12 inches and 12 inches, respectively); enacted limited recreational closures and bag limits; and instituted seasonal, areal, or state-wide commercial landings/gear restrictions. Minimum codend mesh regulations have been promulgated in directed winter flounder fisheries: 5 inch for NJ and NY, 5.5 inch for CT, 5 inch for RI, and 6 inch for MA.
Winter flounder in the Exclusive Economic Zone (EEZ) are managed under the Northeast Multispecies Fishery FMP developed by the NEFMC. The principle catch of winter flounder in the EEZ has recently occurred as bycatch in directed trawl fisheries for Atlantic cod, haddock, and yellowtail flounder. The management unit encompasses the multispecies finfish fishery that operates from eastern Maine through Southern New England (72°30'). At least one offshore stock, on Georges Bank, has been identified. The FMP extends authority over vessels permitted under the FMP even while fishing in state waters if federal regulations are more restrictive than the state regulations.
The Multispecies FMP was implemented in September, 1986, imposing a codend minimum mesh size of 5.5 inches (previously 5.1 inches) in the large-mesh regulatory area of Georges Bank and the offshore portion of Gulf of Maine. There were closed areas and seasons for haddock and yellowtail flounder. In the western Gulf of Maine, vessels were required to enroll in an Exempted Fisheries Program in order to target small-mesh species such as shrimp, dogfish, or whiting. The bycatch restrictions specified area and season and limited groundfish bycatch to 25% of trip and 10% for the reporting period. In southern New England waters, the groundfish bycatch on vessels fishing with small mesh was not limited in any way. There was a 11 inch 140 36th SAW Consensus Summary
minimum size for winter flounder which corresponded with the length at first capture (near zero percent retention) for 5.5 inch diamond mesh. Although the Multispecies FMP was amended four times by 1991, it was widely recognized that many stocks, including winter flounder, were being overfished.
Time-specific stock rebuilding schedules were a part of Multispecies FMP Amendment 5 which took effect in May, 1994. The rebuilding target for winter flounder, a so-called "large-mesh" species, was F20% within 10 years. Along with a moratorium on issuance of additional vessel permits, the cornerstone of Amendment 5 was an effort reduction program that required "large-mesh" groundfish vessels to limit days at sea, which would be reduced each year. There was an exemption from effort reduction requirements for groundfishing vessels less than 45 feet in length and for "day boats" (from 2:1 layover day ratio requirement). Draggers retaining more than the "possession limit" of groundfish (10%, by weight, up to 500 lbs) were required to fish with either 5.5 inch diamond or square mesh in Southern New England or 6 inch throughout the net in the regulated mesh area of Georges Bank/ Gulf of Maine, respectively. The possession limit was allowed when using small mesh within the western Gulf of Maine (except Jeffreys Ledge and Stellwagon Bank) and in Southern New England. Vessels fishing in the EEZ west of 72° 30' (the longitude of Shinnecock Inlet, NY) were required to abide by 5.5 inch diamond or 6 inch square codend mesh size restrictions consistent with the Summer Flounder FMP. The minimum landed size of winter flounder increased to 12 inches, appropriate for the increased mesh size in order to reduce discards. There were many additional rules including time/area closures for sink gillnet vessels, seasonal netting closures of prime fishing areas on Georges Bank (Areas I and II), and on Nantucket Shoals to protect juvenile yellowtail flounder.
At the end of 1994, the NEFMC reacted to collapsed stocks of Atlantic cod, haddock, and yellowtail flounder on Georges Bank by recommending a number of emergency actions to tighten existing regulations reducing fishing mortality. Prime fishing areas on Georges Bank (Areas I &
II), and the Nantucket Lightship Area were closed. The NEFMC also addressed expected re-direction of fishing effort into Gulf of Maine and Southern New England while, at the same time, developing Amendment 7 to the Multispecies FMP. Under Amendment 7, days-at-sea controls were extended, and any fishing by an EEZ-permitted vessel required use of not less than 6 inch diamond or square mesh in Southern New England east of 72° 30'. Framework 27 in 1999 increased the square mesh minimum size to 6.5 inches in the Gulf of Maine, Georges Bank, and Southern New England mesh areas. Amendment 9 revised the overfishing definitions for New England groundfish, and new overfishing definitions for SNE/MA winter flounder were recommended by SARC 28 (NEFSC 1999).
STOCK STRUCTURE Although stock groups consist of an assemblage of adjacent estuarine spawning units, the ASMFC FMP originally defined three coastal management units based on similar growth, 36th SAW Consensus Summary 141
maturity and seasonal movement patterns: Gulf of Maine, Southern New England and Mid-Atlantic. Boundaries for a total of four winter flounder stock units as originally defined in the ASMFC management plan (Howell et al., 1992) were:
Gulf of Maine: Coastal Maine, New Hampshire, and Massachusetts north of Cape Cod Southern New England: Coastal Massachusetts east and south of Cape Cod, including Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, Block Island Sound, Rhode Island Sound, Rhode Island coastal ponds and eastern Long Island Sound to the Connecticut River, including Fishers Island Sound, NY.
Mid-Atlantic: Long Island Sound west of the Connecticut River to Montauk Point, NY, including Gardiners and Peconic Bays, coastal Long Island, NY, coastal New Jersey and Delaware.
Georges Bank In the current and three previous assessments (e.g., NEFSC 1996, ASMFC 1998, NEFSC 1999) the Southern New England and Mid-Atlantic units have been combined into a single stock complex for assessment purposes. A review of tagging studies for winter flounder (Howell 1996) indicates dispersion (and hence mixing) has occurred between the previously defined Southern New England and Mid-Atlantic units. Howell (1996) noted that differences in growth and maturity among samples from Southern New England to the Mid-Atlantic may reflect discrete sampling along a gradient of changing growth and maturity rates over the range of a stock complex. Differences in growth rates within the Mid-Atlantic unit were observed to be greater than differences between Mid-Atlantic and Southern New England units (Howell, 1996).
In offshore waters, the length structure of winter flounder caught in NEFSC research surveys is similar from Southern New England to New Jersey. Most commercial landings are obtained in these offshore regions (greater than 3 miles from shore).
Stock Boundaries and associated Statistical Areas The Gulf of Maine stock complex extends along the coast of eastern Maine to Provincetown, MA, corresponding to NEFSC commercial fishery statistical division 51. Recreational landings from Maine, New Hampshire and northern Massachusetts (northern half of Barnstable County and north to New Hampshire border) are associated with this stock complex.
The Southern New England/Mid-Atlantic stock complex extends from the coastal shelf east of Provincetown, MA southward along the Great South Channel (separating Nantucket Shoals and Georges Bank) to the southern geographic limits of winter flounder. NEFSC commercial fishery statistical areas within this boundary are 521 and 526, and statistical divisions 53, 61, 62, and 63.
The corresponding recreational areas are southern Massachusetts (the southern half of Barnstable County; Dukes, Nantucket and Bristol counties), Rhode Island, Connecticut, New York, New 142 36th SAW Consensus Summary
Jersey, Delaware, Maryland and Virginia. NEFSC survey strata included for this stock extend from the waters of outer Cape Cod to the south and west.
The Georges Bank stock extends eastward of the Great South Channel, including statistical areas 522, 525, and 551-562.
FISHERY DATA Landings After reaching an historical peak of 11,977 metric tons (mt) in 1966, then declining through the 1970s, total U.S. commercial landings again peaked at 11,176 mt in 1981, and then steadily declined to a record low of 2,159 mt in 1994. Landings have increased since 1994 to 4,448 mt in 2001 (Table B1.1, Figure B1.1). During 1989-1996, an average of 43% of commercial landings were taken from statistical area 521, 13% from area 526, 13% from area 537, and 11% from area 539, with the remaining landings (20%) obtained from area 538 and divisions 61-62 (Table B1.
2). Since 1993, a larger percentage of the commercial landings has been taken from area 521.
An unusually high proportion of the commercial landings for the stock complex was reported from NEFSC statistical area 521 in 1997 and 2001, with 62% in 1997 and 56% in 2001. When considered along with the distribution of survey catches, this factor indicates that the commercial fishery is focused on winter flounder along the western side of the Great South Channel. The primary gear in the fishery is the otter trawl which accounts for an average of 95% of landings since 1989. Scallop dredges account for 4%, with handlines, pound nets, fyke nets, and gill nets each accounting for about 1% of total landings.
Recreational landings reached a peak in 1984 of 5,772 mt but declined substantially thereafter (Table B1.3, Figure B1.1). Landings have been less than 1,000 mt since 1991, with the lowest estimated landings in 1998 of 290 mt. Landings in 2001 from the Southern New England/Mid Atlantic stock complex were 552 mt. The principal mode of fishing is private/rental boats, with most recreational landings occurring during January to June.
Sampling Intensity Length samples of winter flounder are available from both the commercial and recreational landings. In the commercial fishery, annual sampling intensity varied from 63 to 264 mt landed per 100 lengths measured during 1981-1997 (Table B1.4). Overall sampling intensity was 90 mt per 100 lengths in 1998, 75 mt per 100 lengths in 1999, 59 mt per 100 lengths in 2000, and 71 mt per 100 lengths in 2001 (Table B1.5). In the recreational fishery, annual sampling intensity varied from 36 to 231 mt landed per 100 lengths measured during 1981-1997 (Table B1.6).
Overall sampling intensity was 47 mt per 100 lengths in 1998, 81 mt per 100 lengths in 1999, 519 mt per 100 lengths in 2000, and 109 mt per 100 lengths in 2001 (Table B1.7).
36th SAW Consensus Summary 143
Landed Age Compositions Commercial fishery In the SARC 21 assessment (NEFSC 1996), numbers at age were estimated for 1985-1993 for commercial landings, recreational landings, commercial discards, and recreational discards.
Quarterly or half-year commercial age-length samples were applied to corresponding commercial market category landings at length. Unsampled unclassified landings and landings not represented in the weighout database (i.e., state canvas landings) were assumed to have the same age composition as the initial weighout commercial landings at age. Landings at lengths with no associated age data within the quarter were assigned ages based on age at length from adjacent quarters. A comparison was undertaken among age data collected from inshore regions (where the recreational fishery is prosecuted), to determine if all age data were comparable within the stock complex. Data for ages 3-5 from New Jersey, Connecticut, Massachusetts and NEFSC were compared for 1993-1994. Distributions of length at age from New Jersey and Connecticut were similar, while distributions of length at age from Massachusetts lacked smaller fish at age (Howell 1996).
In the ASMFC 1998 assessment (ASMFC 1998), the Technical Committee attempted to update the catch at age matrix for VPA for 1994-1996. Two key market categories of commercial landings were found to lack port samples: medium fish in the second half of 1995 and large fish in the first half of 1996. In addition, several market categories were poorly sampled: medium fish in the first and second half-year of 1996, and large fish in the second half of 1995. The Technical Committee concluded then that the port sampling was insufficient to characterize the length and age frequency of the commercial landings for 1995-1996, and elected to use a non-age dependent model (ASPIC) to assess the stock complex (ASMFC 1998).
In the SARC 28 assessment (NEFSC 1999), commercial fishery port samples for 1995 and 1996 were supplemented with commercial fishery sea sample length data for the second half of 1995 and 1996, to continue the catch at age series. For the second half-year of 1995, 2,979 sea sample lengths (unclassified by market category) were used in place of the available 702 port sample lengths to construct an unclassified length frequency for the second half-year of 1995 landings.
For the first half-year of 1996, 55 sea sample lengths were combined with 752 port sample lengths to create an unclassified frequency of 807 lengths for the first-half year of 1996 landings.
Also, archived NEFSC research survey and commercial fishery age samples were aged, allowing extension of the NEFSC survey catch at age series back to 1980 and of the fishery catch at age matrix back to 1981 (Table B1.4). Since 1997, port sampling has been adequate to develop the commercial fishery landings at age on a half-year, market category basis across all statistical areas (Tables B1.5 and B1.10).
Recreational fishery Recreational landings at length were estimated seasonally (January-June and July-December) and geographically. Landings were divided into two geographic regions; 1) Massachusetts and Rhode Island (SNE) and 2) Connecticut and south (MA). For the 1981-1984 period, NEFSC spring age-length keys were used to age both area length frequencies. For 1985-1996, MADMF 144 36th SAW Consensus Summary
survey age-length keys were applied to MA-RI data while CTDEP age-length keys were applied to CT-south data, with the exception of 1993 landings which used a combined NJ/CT age-length key. Since 1997, NEFSC spring and fall keys have been used to age all length frequencies (Tables B1.6, B1.7, and B1.10). For the 1998-1999 recreational catch at age, sample lengths were applied to catch numbers on an annual basis for the two regions, due to low samples size.
For the 2000-2001 recreational catch at age, sample lengths were applied to catch numbers on an annual basis for the regions combined, due to low sample sizes in the SNE region (Table B1.7).
Discard estimates and age compositions Commercial fishery In the SARC 21 assessment (NEFSC 1996), the Working Group and the SARC concluded that there were too few Fishery Observer sampled trips in which winter flounder were caught to adequately characterize the overall ratio of discards to landings in the commercial fishery. The Fishery Observer sample length frequency data, however, were judged adequate to help characterize the proportion discarded at length. In the SARC 21 assessment, commercial discards for 1985 to 1993 were estimated from length frequency data from NEFSC and the Massachusetts Division of Marine Fisheries (MADMF) bottom trawl surveys, commercial port sampling of landings at length and Fishery Observer sampling of landings and discard at length.
The method follows an approach described by Mayo et al. (1992). The year was divided into half year periods. Survey length frequency data (MADMF survey in spring and NEFSC in fall) were smoothed using a three point moving average, then filtered through a mesh selection ogive (Simpson 1989) for 4.5 inch mesh (1984-1989), 5 inch mesh (1990-1992, fall 1993) or 5.5 inch mesh (spring, 1993). The 5.5 inch mesh selection curve was calculated using the 5 inch curve adjusted to an L50 for 5.5 inch mesh. The choice of mesh sizes was based on sizes used in the yellowtail assessment for southern New England (Rago et al. 1994) and comparison to length frequencies of commercial landings. The mesh filtering process resulted in a survey length frequency of retained winter flounder. A logistic regression was used to model the percent discarded at length from 1989-1992 sea sampling data, and the resulting percentages at length were applied to the survey numbers at length data to produce the survey-based equivalent of commercial kept and discarded winter flounder. The 1989-1992 average percentage discard at length was applied to 1985-1988. The survey numbers per tow at length "kept" were then regressed against commercial (weighout) numbers landed at length. The linear relationship was calculated for those lengths common to both length frequencies and fitted with an intercept of zero. The slope of the regression provided a conversion factor to re-scale the survey "discard" numbers per tow at length to equivalent commercial numbers at length. The resulting vector of number of fish discarded at length was multiplied by a discard mortality rate of 50% (as averaged in Howell et al., 1992) to produce the vector of fish discarded dead at length per half year. The number of dead discards at length was adjusted by the ratio of weighout landings to total commercial landings and summed across seasons and lengths (and corresponding weight at length) to produce the annual total number and weight of commercial fishery discards for 1985-1993 (Tables B1.10-11, Figure B1.1). In the SARC 28 assessment (NEFSC 1999), this same method using the 4.5 inch mesh ogive and 1989-1992 average discard percentage at length was 36th SAW Consensus Summary 145
used to estimate commercial fishery discards for 1981-1984. NEFSC spring and fall survey age-length keys were applied to convert discard length frequencies to age.
During ASMFC Winter Flounder Technical Committee meetings since 1995, the group has considered the SARC 21 survey length-mesh selection method, NEFSC Fishery Observer data (OB), and NER Vessel Trip Report (VTR) data as sources of information to use in the estimation of commercial fishery discards, with a focus on the latter two sources. The Committee examined the characteristics of both the Fishery Observer and VTR discard data (number of trip samples, frequency distributions of discards to landings ratio per trip, mean and variance of annual half-year discards to landings ratio), and concluded that the VTR mean discard to landed ratio aggregated over all trips in annual half-year season strata (January to June, July to December) provided the most reliable data from which to estimate commercial fishery discards. VTR trawl gear fishery discards to landings ratios on a half-year basis (January to June; July to December) were applied to corresponding commercial fishery landings (all gears) to estimate discards in weight (Table B1.8, Figure B1.1). The Fishery Observer length frequency samples were judged adequate to directly characterize the proportion discarded at length (Table B1.9). The sample proportion at length, converted to weight, was used to convert the discard estimate in weight to numbers at length. As in the SARC 28 assessment (NEFSC 1999), the resulting number of fish discarded at length was multiplied by a discard mortality rate of 50% (as averaged in Howell et al., 1992) to produce the number of fish discarded dead at length. For 1998, discard estimates at length were made by half-year; for 1999-2001, samples length were applied on an annual basis due to low sample sizes (Table B1.9). NEFSC Spring and Fall survey age-length keys were used to convert the discard length frequency to age (Table B1.10).
Recreational fishery A discard mortality of 15% was assumed for recreational discards (B2 category from MRFSS data), as assumed in Howell et al. (1992). Discard losses peaked in 1984-1985 at 0.7 million fish Discards have since declined reaching a low in 1999 of 62,000 fish. In 2001, 81,000 fish were estimated to have been discarded (Table B1.3). In the SARC 21 assessment (NEFSC 1996),
recreational discards for 1985-1993 were assumed to have the same average weight per fish as spring commercial discards, providing estimates of the total weight of recreational discards ranging from 15 mt in 1992 to 230 mt in 1985. Estimates of recreational discard at age for 1985-1993 were developed using state survey length and age data in a manner similar to that for the commercial discard estimates (Tables B1.10-11; see Gibson (1996) for complete description of computation of 1985-1993 recreational discard numbers at length and age).
The SARC was unable to apply the 1985-1993 method to the 1994-1997 or 1981-1984 periods for the SARC 28 assessment, due to data availability problems (NEFSC 1999). Instead, for 1994-1997, the average proportion at age in the 1991-1993 recreational discard was used to apportion the recreational fishery estimate of discard in numbers to length and age. These discards at age were assumed to have the same mean weight as the landed portion at the same ages, and so this method probably slightly overestimates the discard in weight. For 1981-1984, before implementation of the 12 inch (30 cm) minimum landing size in most states (which 146 36th SAW Consensus Summary
encompasses fish up to age 3), it was assumed that all recreational discard would be age 1 and age 2 fish, and so the discard was allocated to ages 1 and 2 in the same relative proportion as those in the landings, and assumed to have the same mean weight at age. SARC 28 (NEFSC 1999) concluded that since the magnitude of the recreational discard is relatively small compared to the total landings and commercial discards, error in estimation of recreational discard at age due to different methods over the time series and/or error is allocation among ages 1 and 2 would have a minimal effect in terms of estimation of population sizes in the VPA.
Since 1997, irregular sampling of the recreational fisheries by state fisheries agencies has indicated that the discard is usually of fish below the minimum landing size of 12 inches (30 cm).
For 1998-2001, the recreational discard has been assumed to have the same length frequency as the landed portion of the catch below 12 inches, and so is still predominantly ages 1, 2, and 3 fish. As with the recreational landings, sample lengths were applied to catch numbers on an annual basis for the two regions for 1998-1999, and on an annual basis for the regions combined for 2000-2001. The recreational discard for 1998-2001 is aged using NEFSC survey spring and fall keys (Table B1.10).
Mean Weights at Age in the Catch Mean weights at age were determined for the landings and discards in the commercial and recreational fisheries. Length frequencies (cm) for each component were converted to weight (kg) using length-weight equations derived from NEFSC survey samples:
Spring surveys: wt = 0.00000997
- length 3.055236 Fall surveys: wt = 0.00000925
- length 3.095188 The equations from the spring and fall surveys were applied to catches during the corresponding time periods. The annual mean weights at age from the commercial and recreational fisheries were used in the virtual population analysis and yield per recruit calculations.
Total Catch Estimates of the total catch of winter flounder during 1981-2001 are presented in Table B1.11.
These estimates include commercial and recreational landings and discards. The total catch during this period has varied from a high of 15,788 mt (34.6 million fish) in 1984 to a low of 3,095 mt (3.6 million fish) in 1994. The total catch has increased since 1995 to 5,102 mt (9.0 million fish) in 2001 (Table B1.11, Figure B1.1). Total catch and mean weights at age as aggregated for input to the VPA (ages 1-7+) are presented in Tables B1.12-13, and Figures B1.2-3.
RESEARCH SURVEY ABUNDANCE AND BIOMASS INDICES State and federal surveys were evaluated as fishery independent indices of winter flounder abundance and biomass. Survey methods (with the exception of Rhode Island and the young-of-36th SAW Consensus Summary 147
year surveys) are reviewed in the proceedings of a 1989 trawl survey workshop sponsored by the ASMFC (Azarovitz et al., 1989).
NEFSC Mean weight and number per tow abundance indices were determined from fall (1963-2001) and spring (1968-2002) NEFSC bottom trawl surveys. Indices from the spring and fall surveys were based on tows in offshore strata 1-12, 25, and 69-76 and inshore strata 1-29 and 45-56. Spring indices prior to 1973 and fall indices prior to 1972 do not include inshore strata. In addition, offshore surveys from 1963-1966 were not conducted south of Hudson Canyon.
A new series of NEFSC winter trawl surveys was begun in February 1992 specifically to provide improved indices of abundance for flatfish, including winter flounder. A modified 36 Yankee trawl is used in the winter survey that differs from the standard trawl employed during the spring and fall surveys in that 1) long trawl sweeps (wires) are added before the trawl doors, to better herd fish to the mouth of the net, and 2) the large rollers used on the standard gear are absent, and only a chain "tickler" and small spacing "cookies" are present on the footrope. This gear is intended to better target flatfish than the gear used in the spring and fall surveys. The geographical coverage of the winter survey is more limited than the spring and fall surveys, due to time limitations and the use of the flatfish net. Inshore strata and offshore deep strata are irregularly sampled, strata east of the Great South Channel are irregularly sampled, and the Gulf of Maine has never been sampled. For winter flounder, the winter survey indices include offshore strata 1-2, 5-6, 9-10, 69, and 73; generally the offshore between 27 to 110 meters depth (15 to 60 fathoms).
Mean weight per tow and number per tow indices for the spring, fall, and winter time series are presented in Table B1.14. Indices dropped from the beginning of the time series in the 1960s to a low point in the early to mid- 1970s, then rose to a peak by the early 1980s. Following several years of high indices, abundance once again declined to below the low levels of the 1970s.
NEFSC survey indices reached near- or record low levels for the time series in the late 1980s-1990s. Indices from the three survey series generally increased during 1993-1998/1999, but have since declined (Figure B1.4).
Massachusetts The Massachusetts Division of Marine Fisheries (MADMF) spring survey from 1978-2001 was used to characterize the abundance of winter flounder. Survey areas from east and south of Cape Cod were used in the analysis (strata 11-21). The MADMF mean number per tow indices steadily declined from a high value of 53.79 in 1979 to a low of 10.66 in 1991, and then increased to 30-40 fish per tow during 1995-1998, before falling again to 16.00 in 2001. Mean weight per tow indices have varied in a similar manner over the time series, ranging from 15-20 kg/tow in the early 1980s to about 5 kg/tow during 2000-2001 (Tables B1.15-16, Figure B1.4).
The MADMF also conducts an annual juvenile winter flounder seine survey during June. The survey has been conducted since 1975 in coastal ponds and estuaries. The index has shown a 148 36th SAW Consensus Summary
general decline in production, with a high of 0.60 fish per haul in 1977 to a low of 0.07 fish per haul in 1993. The 1997 value was 0.39 fish per haul, and has since declined to 0.10 in 2002 (Table B1.17, Figure B1.5).
Rhode Island The Rhode Island Division of Fish and Wildlife (RIDFW) conducts a number of research surveys in Narragansett Bay and Rhode Island coastal waters. A seasonal trawl survey was initiated in 1979 to monitor finfish stocks in Narragansett Bay, Rhode Island Sound and Block Island Sound. The survey employs a stratified random design and collects length, weight, and abundance information. Survey results are expressed as un-weighted catch per tow (Tables B1.15-16). Spring survey indices from 1979-2001 showed a steady decline from high values during 1979-1981 (12-13 kg per tow, 63-88 fish per tow) to a low of 0.22 kg per tow and 2.92 fish per tow in 1993. Spring indices increased to 5.83 kg per tow and 31.78 fish per tow in 1995, before declining again to 3.56 kg per tow and 12.49 fish per tow in 2001 (Figure B1. 4).
Fall survey indices show simliar trends, with peak abundance and biomass during the early and mid 1980s, a decline to low values in the mid-1990s, some rebound during 1995-1997, and a recent decline (Tables B1.15-16).
A juvenile finfish beach seine survey, conducted from June to October since 1986, takes monthly samples at 17 fixed stations in Narragansett Bay. This seine survey provides an index of young-of-year winter flounder. The index shows a great deal of annual variability, although in recent years there have been consistently high levels of recruitment. The index of the 2000 year class is the highest of the time series (Table B1.17, Figure B1.5).
Connecticut The Connecticut Department of Environmental Protection (CTDEP) Long Island Sound Trawl Survey (1984-present) uses a stratified-random design to sample Connecticut and New York waters of the Sound from Groton to Norwalk. Forty sites are sampled monthly (Apr-June, Sept-Oct) across three sediment (mud, sand , transitional) and four depth intervals (<30 ft, 30-60 ft, 60-90 ft, 90+ft). A 14 m otter trawl with 51 mm codend is towed for 30 min at 3.5 kts from a 15.2 m research vessel.
Winter flounder abundance indices are based on April and May sampling. Winter flounder are counted and measured from each tow. Since 1992 composite biomass (0.1kg) has also been recorded from each tow. Otoliths are collected for aging each spring. Aging samples are stratified by month, area (east/west) and size. Subsamples of 5-7 fish per centimeter are collected from fish up to 36 cm and all fish over 36 cm are retained for aging. Aged fish are measured and weighed in the lab and gonad condition is recorded. Gonad weights were also recorded in some years. In recent years approximately 800 flounder have been aged annually. Otoliths are generally aged whole, however larger fish and difficult bones are sectioned for reading. Indices at age are calculated as a proportion of the overall index. Age length keys are applied by area (east-west) 36th SAW Consensus Summary 149
and year where possible and any remaining unaged fish are aged using a pooled area/year key as necessary.
CTDEP indices exhibited several years of high values between 1988 and 1991, declined to a minimum in 1995, and have since increased to about one-half the time series average during 2000-2002 (Tables B1.15-16, Figure B1.4). A separate young of the year survey index shows above average recruitment during 1994-1996, and below average recruitement since. The 2001 year class index is the smallest of the time series (Table B1.17, Figure B1.5).
New York The New York Department of Environmental Conservation (NYDEC) has conducted a small-mesh trawl survey in Peconic Bay since 1985. Winter flounder indices for ages 0 and 1 were evaluated for trends in winter flounder abundance (Tables B1.16-17, Figure B1.5). Young of the year indices have increased in recent years from 0.7 in 1985 to the 1993 index of 4.7 and 1996 index of 3.80. The 1992 index indicated the strongest recent year class with an index of 11.4. The corresponding age 1 indices also indicated strong 1992, 1993, and 1996 year classes.
New Jersey The New Jersey Division of Fish, Game and Wildlife (NJDFW) has conducted a bottom trawl survey in near-shore ocean waters of the state since 1989, and in inshore waters in the Shark and Manasquan Rivers since 1995. Ocean survey samples are collected via a stratified random bottom trawl survey. Surveys are usually conducted in January, April, June, August, and October.
Inshore samples are collected via a random station trawl survey in the main channel of the Shark and Manasquan Rivers. Sampling is conducted in March, April and May and results are pooled to calculate mean number per tow indices. Aging of NJDFW samples started in 1993. During both surveys, a sub-sample of fish are aged(fish are aged from April ocean survey only). Age/length keys are constructed, and all lengths are transformed to ages by applying all lengths to the age/length keys. Number at each age are divided by the number of tows to derive catch at age per tow.
Ocean survey indices (mean number per tow in April) tended to decline between 1989 and 1993, and have been quite variable since 1994, with a time series low in 1996, increasing to above the time series mean in 2002 (Tables B1.15-16, Figures B1.4-5). River survey indices exhibit no trend over the short time series (Table B1.16, Figure B1.5).
Delaware The Delaware Division of Fish and Game (DEDFG) conducts monthly surveys from April to October using a 16 ft. semi-balloon otter trawl with a 0.5 inch stretch mesh liner. An index of young-of-year winter flounder was developed from stations sampled within Indian River and Rehoboth Bays. The re-transformed annual geometric means, presented in Table B1.17, indicate variable annual recruitment with a large year class in 1990. The 1994 index indicates above average recruitment (Table B1.17, Figure B1.5).
150 36th SAW Consensus Summary
ESTIMATES OF MORTALITY AND STOCK SIZE Natural Mortality and Maturity Instantaneous natural mortality (M) for winter flounder was assumed to be 0.20 and constant across ages. Commercial catch at age included fish to age 14, under conditions of relatively high fishing mortality. If M = 0.25, less than 5% of the population would reach age 12 under conditions of no fishing mortality. Therefore, the SARC judged that M = 0.20, which represents a maximum age of 15, was representative of the stock complex throughout its range.
In the SARC 28 review of the SNE/MA winter flounder stock assessment (NEFSC 1999), the SARC recommended re-examination of the maturity schedule used in the yield per recruit (YPR) and virtual population analyses (VPA) to incorporate any recent research results. The SARC 28 and previous assessments used the maturity schedule as published in OBrien et al. (1993) for winter flounder south of Cape Cod, based on data from the MADMF spring trawl survey for strata 11-21 (state waters east of Cape Cod, Nantucket sound, Vineyard Sound, and Buzzards Bay) sampled during 1985-1989 (n = 301 males, n = 398 females). Those data provided estimates of lengths and ages of 50% maturity of 29.0 cm and 3.3 yr for males, and 27.6 cm and 3.0 yr for females, and the following estimated proportions mature at age. The female schedule (with the proportion at age 2 rounded down to 0.00) was used in the SARC 28 assessment YPR and VPA (NEFSC 1999).
Age 1 2 3 4 5 6 7+
Males 0.00 0.04 0.32 0.83 0.98 1.00 1.00 Females 0.00 0.06 0.53 0.95 1.00 1.00 1.00 In response to the SARC 28 recommendation, the SARC has examined NEFSC spring trawl survey data over the 1981-2001 period in an attempt to better characterize the maturity characteristics of the SNE/MA winter flounder stock complex. Data from the NEFSC survey included those judged in the SARC 28 assessment to comprise the SNE/MA complex from Delaware Bay to Nantucket Shoals: NEFSC offshore strata 1-12, 25 and 69-76, and inshore strata 1-29, 45-46. Note that this is a much larger geographic area than that included in the MADMF survey data used in OBrien et al. (1993). Data were analyzed in 5-6 year blocks (1981-1985, 1986-1990, 1991-1995, and 1996-2001) and for the entire time period (1981-2001), for each sex and combined sexes. Observed proportions mature at age were tabulated, and from those data maturity ogives at length and age were calculated to provide estimated proportions mature at age.
In general, the NEFSC maturity data indicated earlier maturity than the MADMF data, with L50% values ranging from 22-25 cm, rather than from 28-29 cm, and with ~50% maturity for age 2 fish, rather than ~50% maturity for age 3 fish. To investigate the apparent inconsistency between the MADMF and NEFSC maturity data, the SARC compared the two data sets over the same time periods (1985-1989, 1990-1995, 1996-2001) for common/adjacent survey strata (MADMF strata 11-12; NEFSC inshore strata 50-56 and offshore strata 10-12 and 25). Note that 36th SAW Consensus Summary 151
the MAMDF data now have about 160 observations for the 1985-1989 period that were added subsequent to the OBrien et al. (1993) work. For comparable time periods and geographic areas, the NEFSC maturity data still consistently indicated a smaller size and younger age of 50%
maturity than the MADMF data. NEFSC L50% and A50% values range from 22-26 cm and about 2.0 yr, while the MADMF values range from 27-30 cm and about 3.0 yr. The difference in values from this comparison was not as large as for the full NEFSC data set extending southward to Delaware Bay, which incorporates components of the stock complex that mature at smaller sizes and younger ages. However, the difference is still nearly a full age class difference at 50%
maturity.
Given that both length and age vary in the same direction, it seems unlikely that the differences could be attributed to aging differences between the two data sets. Since the MADMF and NEFSC geographic areas in this comparison do not match exactly, the difference in maturity rates may be due to the extension of the NEFSC strata to somewhat deeper waters inhabited by fish that mature at a smaller size and younger age (inclusion of fish in offshore strata were necessary for sufficient sample size). Alternatively, for the size range of fish in question (20 to 30 cm length), it may be that immature and mature fish are segregated by area, with mature fish in that size interval tending to occupy inshore areas during the spring, with immature fish tending to remain offshore. Finally, there may be differences in the accuracy and consistency of interpretation of maturity stage between MADMF and NEFSC survey staff.
The SARC considered these data and analyses and the possible causes for the noted inconsistencies, and concluded that more detailed spatial and temporal analyses are needed before revisions to the maturity schedule can be adopted. Therefore, the maturity at age schedule used in the SARC 28 assessment (see above) has been retained for this assessment.
Total Mortality from Mark and Recapture Data Total mortality in two components of the stock were evaluated using recent tag and recapture data. Northeast Utilities Co. marked and recaptured winter flounder in eastern Long Island Sound from 1983-1998 and the RIDFW has conducted winter flounder tagging programs in Narragansett Bay from 1986-1990 and again from 1996-1998. Mortality estimates were made by maximum likelihood methods using the Brownie class of survivorship models (Brownie et al.
1985). Average estimates of fishing mortality for Long Island Sound averaged 0.59 from 1984-1988 and 0.77 from 1989-1993, and 0.65 from 1993-1996. Fishing mortality in 1996 was estimated to be 0.56. Narragansett Bay estimates of fishing mortality ranged from 0.81 to 1.92 and averaged 1.19 from 1986 to 1989. The most recent tag releases in Narragansett Bay indicate that F had dropped to 0.37 in 1996-1997.
Virtual Population Analysis Tuning The Virtual Population Analysis (VPA) was tuned (calibrated) using the NEFSC Woods Hole Fisheries Assessment Compilation Toolbox (FACT) version 1.50 of the ADAPT VPA (Conser and Powers 1990). Abundance indices at age (Tables B1.18-25) were available from several 152 36th SAW Consensus Summary
bottom trawl surveys: NEFSC spring bottom trawl ages 1-7+, NEFSC fall ages 1-5 (advanced to tune January 1 abundance of ages 2-6), NEFSC winter ages 1-5, MADMF spring ages 1-7+,
RIDFW fall seine age 0 (advanced to tune age-1), RIDFW spring ages 1-7+, CTDEP spring ages 1-7+, NYDEC age 0 (advanced to tune age-1) and age-1, MADMF summer seine index of age-0 (advanced to tune age-1), DEDFG juvenile trawl survey age-0 (advanced to tune age-1), NJDFW Ocean trawl survey ages 1-7+, and NJDFW River trawl survey ages 1-7+. The indices from the NEFSC winter trawl survey, NYDEC, and NJDFW were included in the VPA tuning for the first time. Survey indices were selected for inclusion in VPA tuning based on consideration of the partial variance in a VPA trial run including all indices, residual error patterns from the various trail runs, and on the significance of the correlation among indices and with VPA abundance estimates from the trial run including all indices.
The SARC considered eight different configurations of tuning indices. In general, tuning indices were excluded if they exhibited high partial variance (indicating a lack of fit within the VPA model) and low correlation with other indices with similar spatial and temporal characteristics and with the VPA estimates of 2002 stock size. Run W36ALL was the initial trial including all indices. Run W36_28 used the same suite of indices as that selected for the SARC 28 VPA (NEFSC 1999), and therefore did not include new indices available from the NEFSC Winter trawl survey, the NYDEC indices, or the two NJDFW index series. Run W36_1 excluded eight indices with high partial variance within the VPA and low correlation with other indices and/or the VPA estimates of stock size, resulting in improvements both in overall fit (Mean Square Residual (MSR) reduced by 14%) and in the precision of the stock size estimates, relative to the W36ALL configuration. Run W36_2 dropped an additional seven indices from the W36_1 configuration, resulting in further improvements in fit (21% improvement over run W36_1) and precision. This was the run adopted as final by the SARC, and is the basis for all further analyses (Table B1.26).
Run W36_3 dropped an additional two indices (from W36_2) to exam the trade-off between overall model fit (MSR) and the precision of the 2002 stock size estimates as degrees of freedom were further reduced. The SARC concluded that the improvement of run W36_3 in overall fit (7%) was balanced by the decrease in precision at ages 6 and 7+, and so retained run W36_2 as final. Two additional runs excluded all state agency indices (W36NEC) and excluded all NEFSC indices (W36STATE). The W36NEC exhibited a better fit than the W36_2 run, but much lower precision of the 2002 stock size estimates, reflecting the fewer degrees of freedom available. The W36STATE run exhibited the poorest fit of the eight considered, along with the lowest precision of the 2002 stock sizes at ages 4 and older. Run W36_28 provided results intermediate to those from the W36_2 and W36STATE runs. Finally, run W36_2IR was the same as run W36_2, but incorporated the iterative re-weighting option of the VPA tuning, which in a second step of tuning gives more influence to indices that fit best within the analysis (tuning weight in inverse proportion to initial fitted variance). The W36_2IR results were very similar to those of runs W36_2 and W36_3 (Figure B1.6).
36th SAW Consensus Summary 153
Stock size estimates for 2002 in the final W36_2 calibration were moderately precise (initial coefficients of variation ranged from 0.21 at age-3 to 0.38 at age-1). Nearly all surveys had years in which all observations deviated from predicted values in the same direction. For example, most surveys exhibited blocks of negative residuals during the late 1980s, and then blocks of positive residuals during the mid to late 1990s, when residuals for all ages are summed within year and survey series. Residuals by age exhibit a similar pattern of blocking, and a tendency for blocks of positive residuals at younger ages during the mid-1990s to move to older ages later in the VPA time series. This pattern of residuals (i.e., overestimation of stock size by the surveys during the mid-to late 1990s) is reflective of the retrospective pattern of VPA estimates evident for terminal years 1995-1999 (see the following Retrospective Analysis section). The correlation analysis of tuning indices also indicated that there are strong year effects in survey indices, due to annual distribution patterns or local recruitment events. However, in concert, the SARC concluded that the surveys appear to provide geographically balanced tuning.
Exploitation Pattern The exploitation pattern has been variable from year to year, but with the exception of 1996-1997, age-4 fish have been 80%-100% recruited since 1993 (Table B1.26). The SARC noted a recent tendency for partial recruitment at age to decrease substantially at ages 5 and 6 in the terminal year, but further noted that the retrospective analysis indicates that this tendency does not persist, with the expected, flat-topped partial recruitment pattern becoming evident as the VPA converges. For this reason, the average exploitation pattern to be used in yield per recruit analysis and stock projections was calculated as the geometric mean fishing mortality rates for 1998-2000, normalized to age 4. The resulting pattern indicates 1% recruitment at age-1, 27% at age-2 and 75% at age-3. For purposes of yield per recruit and stock projections, full (100%)
recruitment was assumed at ages 4 and older. For consistency with the partial recruitment averages, mean weights at age in the landings, discards, and spawning stock biomass were also averaged over 1998-2000.
Fishing Mortality, Spawning Stock Biomass, and Recruitment During 1981-1993, fishing mortality (fully recruited F, ages 4-5) has varied between 0.4 (1982) and 1.4 (1988), and was as high as 1.2 as recently as 1997. Fishing mortality has been in the range of 0.5-0.6 during 1999-2001 (Table B1.26, Figure B1.7). Accounting for the uncertainty of the 2001 estimate, there is an 80% probability that F in 1997 was between 0.44 and 0.58 (Figure B1.8).
SSB declined from 14,800 mt in 1983 to a record low of 2,700 mt in 1994. SSB has increased since 1994 to 7,600 mt in 2001 (Table B1.26, Figure B1.9). Accounting for the uncertainty of the 2001 estimate, there is an 80% probability that SSB in 2001 was between 6,800 mt and 8,400 mt (Figure B1.8). Recruitment declined from 62.9 million age-1 fish in 1981 to 7.8 million in 1992. Recruitment then averaged 14.7 million fish during 1993-2001, below the VPA time series average of 23.9 million. The 2001 year class is estimated to be the smallest in 22 years, at only 5.7 million fish (Table B1.26, Figure B1.9).
154 36th SAW Consensus Summary
Retrospective analysis A retrospective analysis of the VPA was conducted back to a terminal catch year of 1997.
The VPA exhibits a retrospective pattern of underestimation of F and overestimation of SSB during the late 1990s. The most likely cause of this pattern is a combination of factors including under-reporting of the landings, mis-classification of the landings by stock area, and underestimation of the discards. For 1995-1999, retrospective fishing mortality rates underestimate the current values by an average of 128%, ranging from 232% for 1997 to 44% for 1995. The pattern reversed for 2000 (i.e., F was overestimated), and fishing mortality appears to have been overestimated for 2000 by 7%. The retrospective pattern for spawning stock biomass has been a tendency for overestimation since 1991. The overestimation of SSB averaged 76%
from 1995-1999, and was largest for the 1997 and 1998 terminal years (115% and 98%
overestimation). The retrospective estimation of age-1 recruits indicated a tendency for overestimation during 1993-2000, with recruitment apparently underestimated for 2001 (2000 year class; Table B1.26, Figure B1.10).
Precision of Stock Size, F, and SSB estimates The precision of the 2002 stock size, fishing mortality at age in 2001, and SSB estimates from VPA was evaluated using bootstrap techniques (Efron 1982). Five hundred bootstrap iterations were realized in which errors (differences between predicted and observed survey values) were resampled. Estimates of precision and bias are presented in Table B1.27. Bootstrap estimates of stock size at age indicate low bias (<6%) for ages 1-7+ and bootstrap standard errors provide stock size CVs ranging from 18% at age 3 to 34% at age 1.
Bootstrapped estimates of spawning stock biomass indicate a CV of 9%, with low bias (bootstrap mean estimate of spawning stock biomass of 7,705 mt compared with VPA estimate of 7,643 mt; Table B1.27). There is an 80% probability that spawning stock in 2001 was between 6,800 mt and 8,400 mt (Figure B1.8).
The bootstrap estimates of standard error associated with fishing mortality rates at age indicate good precision. Coefficients of variation for F estimates ranged from 16% at age 3 to 21% at ages 1, 6 and 7+ (Table B1.27). There is an 80% probability that fully recruited F for ages 4-5 in 2001 was between 0.44 and 0.58 (Figure B1.8).
BIOLOGICAL REFERENCE POINTS Yield and Spawning Stock Biomass per Recruit; Stock-recruitment model NEFSC (2002) re-estimated the biological reference points for SNE/MA winter flounder in 2002 using yield and SSB per recruit (Thompson and Bell 1936) and Beverton-Holt stock-recruitment models (Beverton and Holt 1957, Brodziak et al. 2001, Mace and Doonan 1988) based on the SARC 28 assessment (NEFSC 1999). The yield and SSB per recruit analyses indicate that F40% =
36th SAW Consensus Summary 155
0.21 and F0.1 = 0.25 (Figure B1.11). The parametric stock-recruitment model indicated that MSY = 10,600 mt, Fmsy = 0.32, and SSBmsy = 30,100 mt (Figure B1.12).
Biological reference points estimated in NEFSC (2002) were updated by the SARC with the partial recruitment pattern and mean weights at age for 1998-2000 (as noted earlier, the 2001 estimates were not included in the averages due to the retrospective variability of the partial recruitment pattern in the terminal year of the VPA). Given the stability of the input data to these analyses and the consistency of the results with the previous work, the SARC elected to retain the NEFSC (2002) estimates of biological reference points for this assessment. The SARC recommends that these parametric stock-recruitment model reference points be adopted as the basis for the ASMFC and NEFMC FMP overfishing definitions.
PROJECTIONS FOR 2002-2013 Stochastic projections were made based on 500 bootstrapped VPA realizations of stock size in numbers at age in 2002. The stochastic forecasts only incorporate uncertainty in 2002 stock sizes due to survey variability, assume current discard to landings proportions, and are not adjusted for the retrospective pattern in VPA stock size estimates. Partial recruitment to the fishery and percentage discarded were estimated as the geometric mean of VPA estimates for 1998-2000. The 2001 estimates were not included in the averages due to the retrospective variability of the partial recruitment pattern in the terminal year of the VPA. For consistency with the partial recruitment averages, mean weights at age in the stock, landings, and discards were similarly estimated as the weighted (by number landed) geometric mean weight at age from 1998-2000. Age-1 recruitment levels in 2003 and later years are estimated from the stochastic, parametric stock-recruitment relationship estimated in NEFSC (2002). Projections were made through 2013 to respond both to the ASMFC terms of reference and more recent NEFMC Plan Development Team requirements.
If F in 2002 is assumed to be 15% less than F in 2001 (F2002 = 0.43), due to the impact of management measures implemented in response to court orders during 2002, then landings are expected to be about 3,000 mt in 2002. At this reduced F, spawning stock biomass is projected to fall to 5,900 mt in 2002. Given F = 0.43 in 2002, a fishing mortality rate of Freb = 0.24 will be necessary to rebuild the spawning stock to 30,100 mt by 2013 with 50% probability (Table B1.28, Figure B1.13).
POTENTIAL SENSITIVITY OF VPA ESTIMATES TO HYPOTHETICAL NEFSC SURVEY ADJUSTMENTS Acting on the advice of industry members, NEFSC staff inspected the trawl cables (warp) on the NOAA Ship Albatross IV' s sampling equipment on September 3, 2002. It was determined that the marks on the cable attaching scientific survey gear to the vessel were not at true 50 m length 156 36th SAW Consensus Summary
intervals they are intended to indicate. The marks are used by the vessel crew to determine how much cable is deployed. The cable was most recently replaced in February 2000, and used in eight bottom trawl surveys, beginning with Winter 2000 and ending with Spring 2002.
Therefore, it is likely that at times more cable was deployed on one side of the NEFSC trawl survey net than on the other. This is a matter of inches at shorter lengths, and more pronounced as more cable is deployed. For example, with 100 m (328 ft) of cable deployed, just under 1 inch more cable was out on one side; at 300 m (984 ft) the difference was just under 6 ft. Of all tows made in the surveys, 75% deploy 300 m of cable or less. As a result, the NEFSC trawl survey gear may have fished differently during the Winter 2000 through Spring 2002 survey compared to prior surveys, and the data collected (catch per tow, for example) may have been influenced in a way that should be accounted for.
During September 24-27, 2002, video and net sensor equipment were used in experimental tows to both directly and numerically document net performance. Individuals from the region's commercial industry and the fishery management councils were part of the scientific crew during these observations. During October 2-3, 2002, a workshop was convened to examine the data collected and produce a report. The workshop was open to the public, with invited members to include scientists familiar with fishery survey practices, commercial fishermen and gear providers, the region's fishery management councils. As of this writing, the workshop was in progress, and was expected to produce a report detailing correction factors that can then be used in adjusting the NEFRSC survey indices used in this assessment, if needed.
In the interim, to examine the potential sensitivity of the SNE/MA winter flounder VPA to such corrections, hypothetical adjustments have been applied to the NEFSC winter, spring, and fall survey indices used in the SNE/MA winter flounder VPA. NEFSC indices from the Winter 2000 through Spring 2002 surveys were increased by 10%, 25%, and 100% to explore a range of the potential positive adjustments to the indices that might be necessary to account for reduced catch efficiency of the NEFSC survey gear during those surveys. The effect is nearly linear, with F in 2001 ranging from 0.51 for the baseline, W36_2 VPA to 0.36 for the VPA with all NEFSC survey indices increased by 100% (doubled); SSB in 2001 ranged from 7,600 mt for the baseline to 11,300 mt for NEFSC indices increased 100%. In all cases, the fishing mortality rate remained above Fmsy, and SSB remained below one-half Bmsy (Figure B1.14).
CONCLUSIONS The Southern New England/Mid-Atlantic winter flounder stock complex is overfished and overfishing is occurring (Figure B1.15). Fully recruited fishing mortality in 2001 was 0.51 (exploitation rate = 37%), about 60% above Fmsy =0.32. The current VPA indicates there is an 80% chance that the 2001 F was between 0.44 and 0.58. Spawning stock biomass was estimated to be 7,600 mt in 2001, about 25% of SSBmsy = 30,100 mt. There is an 80% chance that the spawning stock biomass was between 6,800 mt and 8,400 mt in 2001.
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The current assessment provides a much more pessimistic evaluation of stock status than the SARC 28 assessment in 1998 (NEFSC 1999). This is mainly due to the retrospective pattern of underestimating F and overestimating SSB in the current VPA. However, while the SNE/MA winter flounder VPA provides uncertain estimates of current F and SSB, it provides a better determination of stock status than reliance on survey indices alone. Managers should recognize that given the estimation uncertainty in the assessment, current fishing mortality rates are likely much higher than the 2001 estimate of 0.51, potentially by nearly 100%. Current SSB may in turn be substantially overestimated.
Spawning stock biomass declined substantially from 13,000-14,000 mt during the early 1980s to 2,700 mt during 1994-1996. SSB has increased since the mid 1990s to about 7,600 mt in 2001 due to reduced fishing mortality rates since 1997. Recruitment to the stock has been below average since 1989, and early indications are that the 2001 year class is the smallest in 22 years.
Forecasts indicate that it will be necessary to reduce the fishing mortality rate to Freb = 0.24 in 2003 and later years to rebuild to spawning stock to the target (SSBmsy = 30,100 mt) by 2013 with 50% probability.
The SARC elected to retain the NEFSC (2002) estimates of biological reference points for SNE/MA winter flounder for this assessment. The SARC recommends that these parametric stock-recruitment model reference points be adopted as the basis for the ASMFC and NEFMC FMP overfishing definitions. These reference points are a technical improvement over the ASMFCs yield per recruit reference points, as they include the estimates of Bmsy, MSY, and Fmsy required by the Sustainable Fisheries Act of 1996.
SARC COMMENTS The SARC noted that while three of the major research recommendations from the SARC 28 assessment had been addressed, three more dealing mainly with the estimates of fishery discards remain unresolved, and should be addressed before the next assessment. The SARC discussed the use of surveys with different recent trends for tuning the VPA. A VPA run using only NEFSC surveys produced a more optimistic view of stock status than a run using only State indices. It was noted that the different trends among State surveys are likely tracking real trends in different portions of the stock complex. Therefore, combining the indices on a spatial scale or weighting them by survey area before tuning the VPA should be explored. The SARC reviewed a run using iterative re-weighting of the indices, which provided results very similar to the final, accepted VPA.
The SARC discussed the process of selecting indices used to tune the VPA, because the current VPA includes three new tuning series for ages 1-7+ (NEFSC winter, NJDFW river, and NJDFW ocean) and two more recruitment indices (NYDEC) not available for the SARC 28 assessment.
The SARC reviewed a VPA run using the same suite of indices as in the last assessment (SARC
- 28) to determine how the addition of the new series had influenced the VPA results. That run 158 36th SAW Consensus Summary
provided results similar to the final VPA. An examination of the utility of a randomization test on survey indices for determining the influence of the indices on VPA results could be informative.
The SARC noted that the current assessment provides a much more pessimistic evaluation of stock status than the SARC 28 assessment in 1998 (NEFSC 1999). This is mainly due to the retrospective pattern of underestimating F and overestimating SSB in the current VPA. It was noted that an increase in the catchability of the survey could produce the observed retrospective pattern. However, there was no reason to suspect an increase in the catchability of the NEFSC and State research surveys used in the VPA tuning. The mis-classification of landings by stock area could also be a cause of the retrospective pattern. However, the SARC noted a similar retrospective pattern in the Gulf of Maine winter flounder assessment, suggesting that significant SNE-MA landings had not been mis-classified into the Gulf of Maine stock area. An underestimation of the discarded proportion of the catch could also produce the observed retrospective pattern. The use of VTR data in estimating commercial fishery discards is a source of uncertainty. Possible significant discarding in the commercial scallop dredge fishery was noted, but current data provide generally small (less than the trawl fishery) and extremely variable estimates of winter flounder discards in the dredge fishery. Finally, the observed retrospective pattern might be caused by under-reporting or underestimation of the commercial or recreational landings. Given the retrospective pattern, the utility of the current SNE-MA winter flounder VPA was evaluated. The SARC concluded that, while the SNE-MA winter flounder VPA provides uncertain estimates of current F and SSB, it still provides the best available determination of stock status.
As one illustration of the possible magnitude of potential missing catch, the SARC noted that it would take roughly a trebling of the catch during the period 1996-1998 to significantly reduce the magnitude of the retrospective pattern in fishing mortality. The SARC noted that retrospective patterns are evident in several of the New England groundfish stock assessments (e.g. GOM winter flounder, SNE-MA, CC/GOM, and GB yellowtail flounder, GB and GOM cod, and witch flounder). Investigation to determine a common cause for this pattern should be pursued.
Alternative assessment methods for dealing with retrospective patterns, such as statistical catch at age models, should be explored.
SOURCES OF UNCERTAINTY
- 1) Stock-specific landings data for 1994 and later are derived by proration from Vessel Trip Report data and are considered provisional.
- 2) Length frequency sampling intensity of the commercial and recreational fishery landings has been low in some recent years, and likely increases the uncertainty of the estimated landings at age.
36th SAW Consensus Summary 159
- 3) Commercial fishery discard estimates are based on rates provided by fishers in the Vessel Trip Reports, owing to inadequate Fishery Observer sampling.
- 4) The SNE-MA winter flounder VPA exhibits a retrospective pattern of underestimating F and overestimating SSB during the late 1990s, increasing the uncertainty of current estimates of F and SSB.
RESEARCH RECOMMENDATIONS New
- 1) Evaluate the maturity at age of fish sampled in the NEFSC fall and winter surveys.
- 2) Consider fieldwork to record ovary weights along with maturity stage data from 20-30 cm fish in the NEFSC and State agency surveys for 1-2 years to help resolve age/size at maturity differences between State and NEFSC surveys.
- 3) Conduct periodic maturity staging workshops involving State and NEFSC trawl survey staff.
- 4) Examine sources of the differences between NEFSC, MA and CT survey maturity (validity of evidence for smaller size or younger age at 50% maturity in the NEFSC data). Compare NEFSC inshore against offshore strata for differences in maturity. Compare confidence intervals for maturity ogives. Calculate annual ogives and investigate for progression of maturity changes over time. Examine maturity data from NEFSC strata on Nantucket Shoals and near Georges Bank separately from more inshore areas. Consider methods for combining maturity data from different survey programs.
- 5) Increase the intensity of commercial fishery discard length sampling.
- 6) Consider post-stratification of NEFSC survey offshore stratum 23, to facilitate inclusion of survey catches from this stratum (east of Cape Cod) in the SNE-MA winter flounder assessment.
- 7) Incorporate State samples (e.g. NY DEC Party Boat Survey and CT DEP Volunteer Angler Survey) in the estimation of recreational fishery landings and discards, if possible.
- 8) Attempt use of a forward projection (statistical catch at age model) in the next assessment.
Old: Pending
- 1) Continue to consider the effects of catch-and-release components of recreational fishery on discard at age (i.e., develop mortality estimates from the American Littoral Society tagging database, if feasible).
160 36th SAW Consensus Summary
- 2) Compare commercial fishery discard estimates from the Mayo survey/mesh algorithm with those from VTR data for comparable time periods.
- 3) Maintain or increase sampling levels (currently supported by individual state funding) and collect age information from MRFSS samples.
- 4) Examine the implications of anthropogenic mortalities caused by pollution and power plant entrainment in estimating yield per recruit, if feasible.
- 5) Examine the implications of stock mixing from data from Great South Channel region.
- 6) Expand sea sampling for estimation of commercial discards.
- 7) Revise the recreational fishery discard estimates by applying a consistent method across all years, if feasible (i.e., the Gibson 1996 method).
Old: Work In Progress
- 1) Re-examine the maturity ogive to incorporate any recent research results.
- 2) Explore the feasibility of stratification of the commercial fishery discard estimation by fishery (e.g., mesh, gear, area).
Old: Completed
- 1) Further examine the comparability of age-length keys from different areas within the stock.
Current comparisons are based on two years and three ages. Conduct an age structure exchange between NEFSC, CT DEP, and MADMF, to ensure consistency in ageing protocol.
- 2) Age the archived MA DMF survey age samples for 1978-1989.
- 3) Compile NEFSC Winter Survey abundance indices for winter flounder and evaluate their utility.
- 4) Evaluate the utility of MADMF sea sample data for winter flounder in estimating commercial fishery discards.
36th SAW Consensus Summary 161
LITERATURE CITED ASMFC. 1998. Assessment of the Southern New England/Mid-Atlantic and Gulf of Maine Winter Flounder stocks: a report by the ASMFCs Winter Flounder Technical Committee. ASMFC WFTC Document 98-01. 31 p + app.
Azarovitz, T., J. McGurrin and R. Seagraves, eds. 1989. Proceedings of a workshop on bottom trawl surveys. Atlantic States Marine Fisheries Commission. Special Report No. 17.
August 1989.
Beverton, R.J.H., and S.J. Holt. 1957. On the dynamics of exploited fish populations.
Chapman and Hall, London. Facsimile reprint 1993.
Bigelow, H. and W. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin of the Fish and Wildlife Service. V. 53. Fishery Bulletin 74.
Brodziak, J.T.K., W.J. Overholtz, and P. Rago. 2001. Does spawning stock affect recruitment of New England groundfish? Can. J. Fish. Aquat. Sci. 58(2): 306-318.
Brownie, C., D. Anderson, K. Burnham and D. Robson. 1985. Statistical inference from band recovery data: a handbook. U.S. Fish and Wildlife Service, Res. Publ. No. 156. 305 pp.
Conser, R. and J. Powers. 1990. Extension of the ADAPT VPA tuning method designed to facilitate assessment work on tuna and swordfish stocks. Int. Comm. Conserv. Atlantic Tunas. Coll. Vol. Sci. Pap. 32: 461-467.
Efron, B. 1982. The jackknife, the bootstrap and other resampling plans. Phila. Soc. for Ind.
and Appl. Math. 38.
Gibson, M. 1996. Age structure of winter flounder B2 type recreational discards estimated from inshore trawl survey lengths, age-length keys, and minimum size regulations. NEFSC Res. Doc.96-05b.
Howe, A., and P. Coates. 1975. Winter flounder movements, growth, and mortality off Massachusetts. Trans. Am. Fish. Soc. 104: 13-29.
Howell, P. 1996. Identification of stock units. NEFSC Res. Doc.96-05b.
Howell, P., A. Howe, M. Gibson and S. Ayvasian. 1992. Fishery management plan for inshore stocks of winter flounder. Atlantic States Marine Fisheries Commission. Fisheries Management Report No. 21. May, 1992.
162 36th SAW Consensus Summary
Mace, P.M., and I..J. Doonan. 1988. A generalized bioeconomic simulation model for fish population dynamics. N.Z. Fish. Ass. Res. Doc. 88/4.
Mayo, R. K., L. O'Brien, and N. Buxton. 1992. Discard estimates of American plaice, Hippoglossoides platessoides, in the Gulf of Maine northern shrimp fishery and the Gulf of Maine-Georges Bank large-mesh otter trawl fishery. SAW 14 Res. Doc. 14/3, 40 pp.
NEFSC. 1996. Report of the 21st Northeast Regional Stock Assessment Workshop (21st SAW):
Stock Assessment Review Committee (SARC) consensus summary of assessments.
Northeast Fish. Sci. Cent. Ref. Doc.96-05d. 200 p.
NEFSC. 1999. Report of the 28th Northeast Regional Stock Assessment Workshop (28th SAW):
Stock Assessment Review Committee (SARC) consensus summary of assessments.
Northeast Fish. Sci. Cent. Ref. Doc. 99-08. 304 p.
NEFSC. 2001. Assessment of 19 Northeast Groundfish Stocks through 2000: a report to the New England Fishery Management Councils Multi-Species Monitoring Committee.
Northeast Fish. Sci. Cent. Ref. Doc. 01-20. 217 p.
NEFSC. 2002. Final report of the Working Group on re-evaluation of biological reference points for New England groundfish. Northeast Fish. Sci. Cent. Ref. Doc. 02-04. 123 p.
O'Brien, L., J. Burnett, and R. Mayo. 1993. Maturation of nineteen species of finfish off the northeast coast of the United States, 1985-1990. NOAA Tech. Rep. NMFS 113. 66 pp.
Rago, P., W. Gabriel, and M. Lambert. 1994. Assessment of yellowtail flounder Pleuronectes ferrugineus. NEFSC Ref. Doc. 94-02.
Simpson, D.G. 1989. Codend selection of winter flounder Pseudopleuronectes americanus.
NOAA Tech. Rpt. NMFS 75. 10 p.
Thompson, W. F. and F. H. Bell. 1934. Biological statistics of the Pacific halibut fishery. 2.
Effect of changes in intensity upon total yield and yield per recruit of gear. Rep. Int. Fish.
(Pacific halibut) Comm. 8: 49 p.
36th SAW Consensus Summary 163
Table B1.1. Winter flounder commercial landings (metric tons) for Southern New England/Mid-Atlantic stock complex area (U.S. statistical reporting areas 521, 526, divisions 53, 61-63) as reported by NEFSC weighout, state bulletin and general canvas data.
Year Metric Tons 1964 7,474 1965 8,678 1966 11,977 1967 9,478 1968 7,070 1969 8,107 1970 8,603 1971 7,367 1972 5,190 1973 5,573 1974 4,259 1975 3,982 1976 3,265 1977 4,413 1978 6,327 1979 6,543 1980 10,627 1981 11,176 1982 9,438 1983 8,659 1984 8,882 1985 7,052 1986 4,929 1987 5,172 1988 4,312 1989 3,670 1990 4,232 1991 4,823 1992 3,816 1993 3,010 1994 2,159 1995 2,634 1996 2,781 1997 3,441 1998 3,208 1999 3,444 2000 3,783 2001 4,448 164 36th SAW Consensus Summary
Table B1.2. Distribution of commercial landings (percentage of annual total) of winter flounder from Southern New England/Mid-Atlantic stock complex area by U.S. statistical reporting area.
Area Year 521 526 537 538 539 611 612 613 614-622 1989 33.2 10.8 18.9 7.0 12.1 7.1 5.5 4.2 1.2 1990 45.2 16.8 6.1 4.9 9.5 11.1 4.1 2.0 0.1 1991 46.4 14.7 10.8 1.7 13.7 5.7 3.6 2.9 0.4 1992 37.0 12.5 17.4 2.4 9.4 10.1 4.5 3.4 3.4 1993 46.6 10.0 10.8 2.4 8.2 7.7 4.2 8.0 2.1 1994 41.8 13.3 3.3 0.1 17.6 10.3 6.5 3.1 3.3 1995 43.3 9.1 6.7 1.6 15.7 10.8 9.3 2.1 1.4 1996 47.3 12.0 10.8 1.4 12.3 11.0 2.5 2.4 0.3 1997 62.8 3.1 7.5 1.5 12.3 8.5 2.0 2.1 0.2 1998 49.5 12.4 7.6 0.6 15.2 9.9 1.8 2.4 0.6 1999 48.7 12.3 6.9 0.4 13.2 8.2 6.4 2.4 1.5 2000 44.1 7.4 10.7 0.8 15.1 8.5 7.2 4.8 1.4 2001 55.8 7.2 7.4 0.1 9.7 7.7 7.4 3.1 1.6 36th SAW Consensus Summary 165
Table B1.3. Estimated number (N, 000's) and weight (mt) of winter flounder caught, landed, and discarded in the recreational fishery, Southern New England/Mid-Atlantic stock complex.
Year Catch N Landed N Released N 15% Release Landings (A+B1+B2) (A+B1) (B2) Mortality (A+B1; mt) 1981 11,006 8,089 2,916 437 3,050 1982 10,665 8,392 2,273 341 2,457 1983 11,010 8,365 2,645 397 2,524 1984 17,723 12,756 4,967 745 5,772 1985 18,056 13,297 4,759 714 5,198 1986 9,368 6,995 2,374 356 2,940 1987 9,213 6,900 2,313 347 3,141 1988 10,134 7,358 2,775 416 3,423 1989 5,919 3,682 2,236 335 1,802 1990 3,827 2,486 1,340 201 1,063 1991 4,325 2,795 1,530 230 1,214 1992 1,360 806 555 83 393 1993 2,211 1,180 1,031 155 543 1994 1,829 1,209 620 93 598 1995 1,850 1,390 461 69 661 1996 2,679 1,554 1,125 169 689 1997 1,901 1,207 694 104 621 1998 1,008 584 425 64 290 1999 1,071 658 412 62 320 2000 2,043 1,346 697 105 831 2001 1,441 901 540 81 552 166 36th SAW Consensus Summary
Table B1.4. Winter flounder commercial fishery landed sample lengths (number of fish measured) used for Southern New England/Mid-Atlantic stock complex, 1981-1997. Landings are in metric tons.
Year Landings Lengths Metric tons per measured 100 lengths 1981 11,176 4,230 264 1982 9,438 5,796 163 1983 8,659 5,601 155 1984 8,882 3,697 240 1985 7,052 6,407 110 1986 4,929 5,120 96 1987 5,172 5,271 98 1988 4,312 4,208 102 1989 3,670 3,525 104 1990 4,232 4,088 104 1991 4,823 3,058 158 1992 3,816 4,163 92 1993 3,010 2,354 128 1994 2,159 2,593 83 1995 2,634 4,153 63 1996 2,781 2,019 138 1997 3,441 4,005 86 36th SAW Consensus Summary 167
Table B1.5. Winter flounder commercial fishery landed sample lengths (number of fish measured) used for Southern New England/Mid-Atlantic stock complex, 1998-2001. Landings are in metric tons.
1998 Market Category Sample Type Season Unclass. Small Medium Large Total Port Jan-Jun 162 105 767 205 1239 Port Jul-Dec 780 794 558 210 2342 Total lengths used 942 899 1325 415 3581 Landings 644 1453 438 673 3208 Metric tons per 100 lengths 68 162 33 162 90 1999 Market Category Sample Type Season Unclass. Small Medium Large Total Port Jan-Jun 978 334 502 522 2336 Port Jul-Dec 1403 464 105 299 2271 Total lengths used 2381 798 607 821 4607 Landings 838 1566 290 750 3444 Metric tons per 100 lengths 35 196 48 91 75 2000 Market Category Sample Type Season Unclass. Small Medium Large Total Port Jan-Jun 808 377 1868 126 3179 Port Jul-Dec 845 565 1025 839 3274 Total lengths used 1653 942 2893 965 6453 Landings 848 451 1670 815 3784 Metric tons per 100 lengths 51 48 58 84 59 168 36th SAW Consensus Summary
Table B1.5 continued.
2001 Market Category Sample Type Season Unclass. Small Medium Large Total Port Jan-Jun 557 510 1067 636 2770 Port Jul-Dec 203 387 1234 1661 3485 Total lengths used 760 897 2301 2297 6255 Landings 908 1101 1475 962 4446 Metric tons per 100 lengths 119 123 64 42 71 36th SAW Consensus Summary 169
Table B1.6. Winter flounder recreational fishery landed sample lengths (number of fish measured) used for Southern New England/Mid-Atlantic stock complex, 1981-1997. Landings are in metric tons.
Year Landings Lengths Metric tons per measured 100 lengths 1981 3,050 1,725 177 1982 2,457 1,971 125 1983 2,524 2,587 98 1984 5,772 3,123 185 1985 5,198 2,357 221 1986 2,940 2,237 131 1987 3,141 1,360 231 1988 3,423 1,944 176 1989 1,802 2,810 64 1990 1,063 2,548 42 1991 1,214 1,755 69 1992 393 1,083 36 1993 543 1,288 42 1994 598 948 63 1995 661 767 86 1996 689 936 74 1997 621 752 83 170 36th SAW Consensus Summary
Table B1.7. Winter flounder recreational fishery sample lengths (number of fish measured) used for Southern New England/Mid-Atlantic stock complex, 1998-2001. SNE = MA & RI; MA =
CT and states south. Landings are in metric tons.
Season/area 1998 1999 2000 2001 Jan-Jun/SNE 105 77 7 80 Jan-Jun/MA 405 256 105 387 Jul-Dec/SNE 85 48 0 3 Jul-Dec/MA 21 14 48 38 Total lengths 616 395 160 508 Landings (A+B1.) 290 320 831 552 Metric tons per 100 Lengths 47 81 519 109 36th SAW Consensus Summary 171
Table B1.8. Winter flounder NEFSC Domestic Fishery Observer Program (OB) and NER Vessel Trip Report (VTR) data: number of OB trips with landed winter flounder (to estimate discards to landings ratio), OB discards to landings ratio, number of VTR trips with winter flounder landings that discarded any species, and VTR discards to landings ratio. VTR data available for 1994 and subsequent years.
Year Half-year OB trips OB ratio VTR Trips VTR ratio 1989 Jan-Jun 22 0.235 Jul-Dec 28 0.299 1990 Jan-Jun 21 0.069 Jul-Dec 18 0.227 1991 Jan-Jun 46 0.579 Jul-Dec 42 0.283 1992 Jan-Jun 17 0.021 Jul-Dec 21 0.076 1993 Jan-Jun 11 0.299 Jul-Dec 22 0.32 1994 Jan-Jun 13 0.304 1519 0.241 Jul-Dec 12 2.84 1488 0.091 1995 Jan-Jun 20 0.044 1484 0.072 Jul-Dec 36 0.289 764 0.028 1996 Jan-Jun 18 0.358 1002 0.088 Jul-Dec 38 0.115 576 0.05 1997 Jan-Jun 27 0.175 2138 0.145 Jul-Dec 18 0.021 1766 0.16 172 36th SAW Consensus Summary
Table B1.8 continued.
Year Half-year OB trips OB ratio VTR Trips VTR ratio 1998 Jan-Jun 6 0.306 2114 0.265 Jul-Dec 18 0.437 1424 0.292 1999 Jan-Jun 13 11.842 2570 0.102 Jul-Dec 7 0.005 1554 0.238 2000 Jan-Jun 20 0.095 2104 0.16 Jul-Dec 21 0.042 1586 0.043 2001 Jan-Jun 27 0.04 2508 0.061 Jul-Dec 22 0.069 2016 0.025 36th SAW Consensus Summary 173
Table B1.9. Winter flounder commercial fishery discard sample lengths (number of fish measured) used for Southern New England/Mid-Atlantic stock complex, 1994-2001. Discard estimates (before impact of 50% mortality rate) are in metric tons.
Season 1994 1995 1996 1997 Jan-Jun 111 73 358 412 Jul-Dec 196 646 245 556 Total lengths 307 719 603 968 Discard Estimate (before mortality) 608 242 346 534 Metric tons per 100 Lengths 198 34 57 55 Season 1998 1999 2000 2001 Jan-Jun 170 354 353 135 Jul-Dec 604 13 128 0 Total lengths 774 367 481 135 Discard Estimate (before mortality) 911 659 296 167 Metric tons per 100 Lengths 118 180 62 124 174 36th SAW Consensus Summary
Table B1.10. Winter flounder catch at age (number in 000s) for the Southern New England/Mid-Atlantic stock complex.
Commercial Landings Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1981 194 7154 9740 2750 606 178 42 32 0 0 9 0 0 1982 54 6897 8496 2715 488 187 78 59 21 17 7 7 0 1983 6 2795 7114 3957 1322 584 269 91 34 70 6 29 35 1984 0 4518 6367 3197 1503 768 355 158 67 86 27 33 37 1985 27 3936 5688 3052 1014 326 104 32 17 7 5 2 0 1986 0 2122 4187 2206 551 271 84 27 6 3 1 2 0 1987 0 2488 5465 1895 465 122 40 20 14 12 2 0 0 1988 0 2241 3929 1607 412 122 37 24 3 2 1 0 0 1989 0 1542 4057 1747 431 58 34 13 5 1 0 0 0 1990 0 1003 3977 1757 315 95 37 16 0 3 0 0 0 1991 0 1406 4756 2239 447 143 48 16 5 1 1 0 0 1992 0 484 3416 2127 574 111 32 11 3 0 0 0 0 1993 13 885 2516 1377 361 102 71 7 0 0 2 0 1 1994 0 629 804 401 90 14 10 0 0 0 0 0 0 1995 0 73 1537 587 95 24 5 0 0 0 0 0 0 1996 0 606 1146 470 122 17 11 0 0 0 0 0 0 1997 0 1418 2574 1370 356 70 28 12 5 1 0 0 0 1998 0 1021 3057 1483 450 83 60 63 7 0 0 0 0 1999 0 2009 3347 1538 386 59 11 6 0 0 0 0 0 2000 0 1073 2801 1942 592 135 35 12 0 0 0 0 0 2001 0 1727 3263 1851 620 148 53 23 2 3 0 0 0 36th SAW Consensus Summary 175
Table B1.10 continued Commercial Discards Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1981 322 2514 2186 101 0 0 0 0 0 0 0 0 0 1982 43 2817 1219 192 0 0 0 0 0 0 0 0 0 1983 260 2479 2000 467 45 0 0 0 0 0 0 0 0 1984 159 2102 1502 166 6 1 0 0 0 0 0 0 0 1985 22 1504 2516 442 43 4 0 0 0 0 0 0 0 1986 78 2220 2389 205 10 0 0 0 0 0 0 0 0 1987 11 1600 1755 170 9 0 0 0 0 0 0 0 0 1988 6 887 2540 276 20 0 0 0 0 0 0 0 0 1989 315 2724 2131 555 33 2 1 0 0 0 0 0 0 1990 16 781 1433 322 14 0 1 0 0 0 0 0 0 1991 17 1238 1205 227 12 1 0 0 0 0 0 0 0 1992 15 845 787 150 14 1 0 0 0 0 0 0 0 1993 201 849 467 57 6 0 0 0 0 0 0 0 0 1994 44 204 88 8 0 0 0 0 0 0 0 0 0 1995 15 47 41 4 0 0 0 0 0 0 0 0 0 1996 11 64 66 7 1 0 0 0 0 0 0 0 0 1997 373 580 210 31 6 0 0 0 0 0 0 0 0 1998 43 972 407 78 3 0 0 0 0 0 0 0 0 1999 63 583 314 54 23 22 15 0 0 0 0 0 0 2000 68 218 199 34 8 1 6 0 0 0 0 0 0 2001 11 127 111 33 3 0 0 0 0 0 0 0 0 176 36th SAW Consensus Summary
Table B1.10 continued.
Recreational Landings Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1981 776 4054 2426 742 59 4 28 0 0 0 0 0 0 1982 457 4235 2716 823 122 26 13 0 0 0 0 0 0 1983 289 1630 4194 1702 427 112 11 0 0 0 0 0 0 1984 294 4258 6224 1565 267 107 41 0 0 0 0 0 0 1985 219 1585 4270 2558 1895 1513 878 0 335 44 0 0 0 1986 106 1765 2432 1797 491 171 81 77 51 8 17 0 0 1987 16 926 1736 1023 2229 633 82 115 64 77 0 0 0 1988 21 534 2858 2078 775 857 128 51 37 20 0 0 0 1989 99 739 944 1200 385 161 91 36 16 8 3 1 0 1990 7 189 814 851 439 101 52 20 3 3 0 2 5 1991 13 232 1122 879 399 107 38 0 1 0 3 0 0 1992 3 123 235 303 85 50 7 0 0 0 0 0 0 1993 31 233 321 289 218 54 20 10 4 2 0 0 0 1994 5 203 240 303 220 149 89 0 0 0 0 0 0 1995 0 30 268 298 321 267 206 0 0 0 0 0 0 1996 0 106 200 630 220 240 157 0 0 0 0 0 0 1997 1 82 497 410 178 36 0 0 0 0 0 0 0 1998 2 89 191 235 58 7 1 0 0 0 0 0 0 1999 1 101 340 151 49 16 0 0 0 0 0 0 0 2000 0 113 440 472 262 44 14 0 0 0 0 0 0 2001 1 84 267 303 168 62 16 0 0 0 0 0 0 36th SAW Consensus Summary 177
Table B1.10 continued.
Recreational Discards Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1981 70 367 0 0 0 0 0 0 0 0 0 0 0 1982 33 308 0 0 0 0 0 0 0 0 0 0 0 1983 62 337 0 0 0 0 0 0 0 0 0 0 0 1984 48 697 0 0 0 0 0 0 0 0 0 0 0 1985 9 340 363 2 0 0 0 0 0 0 0 0 0 1986 32 222 93 9 0 0 0 0 0 0 0 0 0 1987 47 254 43 3 1 0 0 0 0 0 0 0 0 1988 57 279 76 3 0 0 0 0 0 0 0 0 0 1989 49 240 45 1 0 0 0 0 0 0 0 0 0 1990 12 136 51 2 0 0 0 0 0 0 0 0 0 1991 22 151 56 0 0 0 0 0 0 0 0 0 0 1992 7 51 19 1 0 0 0 0 0 0 0 0 0 1993 29 95 26 4 0 0 0 0 0 0 0 0 0 1994 12 60 21 0 0 0 0 0 0 0 0 0 0 1995 9 45 15 0 0 0 0 0 0 0 0 0 0 1996 21 110 37 0 0 0 0 0 0 0 0 0 0 1997 11 55 19 0 0 0 0 0 0 0 0 0 0 1998 5 49 8 1 0 0 0 0 0 0 0 0 0 1999 2 53 6 1 0 0 0 0 0 0 0 0 0 2000 0 38 60 7 0 0 0 0 0 0 0 0 0 2001 1 49 27 5 0 0 0 0 0 0 0 0 0 178 36th SAW Consensus Summary
Table B1.10 continued.
Total Catch Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 Total 1981 1362 14089 14352 3593 665 182 70 32 0 0 9 0 0 34354 1982 587 14257 12421 3730 610 213 91 59 21 17 7 7 0 32020 1983 617 7241 13308 6126 1794 696 280 91 34 70 6 29 35 30327 1984 501 11575 14093 4928 1776 876 396 158 67 86 27 33 37 34553 1985 277 7366 12836 6054 2953 1843 982 32 352 52 5 2 0 32753 1986 215 6327 9102 4216 1053 442 165 104 57 10 19 2 0 21712 1987 73 5268 8999 3091 2703 755 122 135 78 89 2 0 0 21315 1988 84 3941 9402 3964 1207 979 165 75 39 22 1 0 0 19880 1989 463 5246 7176 3503 849 222 126 49 21 9 3 1 0 17668 1990 36 2109 6275 2931 767 196 89 36 4 5 0 2 5 12455 1991 53 3027 7140 3344 858 251 87 16 6 1 4 0 0 14788 1992 25 1503 4457 2581 674 162 38 11 3 0 0 0 0 9455 1993 274 2062 3329 1728 585 157 91 17 4 2 2 0 1 8251 1994 61 1097 1152 713 311 162 99 0 0 0 0 0 0 3595 1995 24 195 1862 889 415 291 211 0 0 0 0 0 0 3887 1996 32 886 1450 1107 343 258 168 0 0 0 0 0 0 4244 1997 385 2135 3300 1811 540 106 28 12 5 1 0 0 0 8323 1998 50 2132 3663 1797 511 90 61 63 7 0 0 0 0 8374 1999 66 2746 4008 1744 458 97 26 6 0 0 0 0 0 9150 2000 69 1442 3500 2455 862 180 55 12 0 0 0 0 0 8575 2001 13 1987 3668 2191 790 211 69 23 2 3 0 0 0 8957 36th SAW Consensus Summary 179
Table B1.11. Total winter flounder recreational and commercial catch for the Southern New England/Mid-Atlantic stock complex in weight (mt) and numbers (000s).
Year Commercial Commercial Recreational Recreational Total %
Landings Discards Landings Discards Catch Discards/Total mt 000s mt 000s mt 000s mt 000s mt 000s mt 000s 1981 11,176 20,705 1,343 5,123 3,050 8,089 88 437 15,657 34,354 9.1 16.2 1982 9,438 19,016 1,149 4,271 2,457 8,392 66 341 13,110 32,020 9.3 14.4 1983 8,659 16,312 1,311 5,251 2,524 8,365 125 399 12,619 30,327 11.4 18.6 1984 8,882 17,116 986 3,936 5,772 12,756 148 745 15,788 34,553 7.2 13.5 1985 7,052 14,211 1,534 4,531 5,198 13,297 230 714 14,014 32,753 12.6 16.0 1986 4,929 9,460 1,273 4,902 2,940 6,994 66 356 9,208 21,712 14.5 24.2 1987 5,172 10,524 950 3,545 3,141 6,899 61 347 9,324 21,315 10.8 18.3 1988 4,312 8,377 904 3,728 3,423 7,359 69 416 8,708 19,880 11.2 20.8 1989 3,670 7,888 1,404 5,761 1,802 3,684 49 335 6,925 17,668 21.0 34.5 1990 4,232 7,202 673 2,567 1,063 2,485 31 201 5,999 12,455 11.7 22.2 1991 4,823 9,063 784 2,701 1,214 2,794 51 230 6,872 14,788 12.2 19.8 1992 3,816 6,759 511 1,811 393 802 15 83 4,735 9,455 11.1 20.0 1993 3,010 5,336 457 1,580 543 1,180 31 155 4,041 8,251 12.1 21.0 1994 2,159 1,948 304 344 598 1,210 34 93 3,095 3,595 10.9 12.2 1995 2,634 2,321 121 107 661 1,390 23 69 3,439 3,887 4.2 4.5 1996 2,781 2,372 173 149 689 1,555 64 168 3,707 4,244 6.4 7.5 1997 3,441 5,834 267 1,200 618 1,204 26 85 4,352 8,323 6.7 15.4 180 36th SAW Consensus Summary
Table B1.11 continued.
Year Commercial Commercial Recreational Recreational Total %
Landings Discards Landings Discards Catch Discards/Total mt 000s mt 000s mt 000s mt 000s mt 000s mt 000s 1998 3,208 6,224 456 1,503 290 584 13 64 3,967 8,375 11.8 18.7 1999 3,444 7,356 329 1,074 320 658 14 62 4,107 9,150 8.4 12.4 2000 3,783 6,590 148 534 831 1,346 30 105 4,792 8,575 3.7 7.5 2001 4,448 7,690 83 285 552 901 19 81 5,102 8,957 2.0 4.1 36th SAW Consensus Summary 181
Table B1.12. Total fishery catch at age used as input to Virtual Population Analysis (VPA) for the Southern New England/Mid-Atlantic winter flounder stock complex.
Year Age 1 2 3 4 5 6 7+
1981 1362 14089 14352 3593 665 182 111 1982 587 14257 12421 3730 610 213 202 1983 617 7241 13308 6126 1794 696 545 1984 501 11575 14093 4928 1776 876 804 1985 277 7366 12836 6054 2953 1843 1424 1986 215 6327 9102 4216 1053 442 357 1987 73 5268 8999 3091 2703 755 426 1988 84 3941 9402 3964 1207 979 303 1989 463 5246 7176 3503 849 222 209 1990 36 2109 6275 2931 767 196 141 1991 53 3027 7140 3344 858 251 115 1992 25 1503 4457 2581 674 162 53 1993 274 2062 3329 1728 585 157 116 1994 61 1097 1152 713 311 162 99 1995 24 195 1862 889 415 291 211 1996 32 886 1450 1107 343 258 168 1997 385 2135 3300 1811 540 106 46 1998 50 2132 3663 1797 511 90 131 1999 66 2746 4008 1744 458 97 32 2000 69 1442 3500 2455 862 180 67 2001 13 1987 3668 2191 790 211 97 182 36th SAW Consensus Summary
Table B1.13. Total fishery mean weights at age used as input to Virtual Population Analysis (VPA) for the Southern New England/Mid-Atlantic winter flounder stock complex.
Year Age 1 2 3 4 5 6 7+
1981 0.130 0.276 0.478 0.802 1.065 1.243 1.202 1982 0.090 0.261 0.438 0.694 1.048 1.253 1.837 1983 0.195 0.237 0.353 0.516 0.774 1.046 1.552 1984 0.146 0.258 0.366 0.542 0.693 0.913 1.282 1985 0.111 0.282 0.364 0.482 0.522 0.467 0.613 1986 0.129 0.292 0.398 0.480 0.685 0.879 0.961 1987 0.046 0.287 0.384 0.551 0.475 0.564 0.853 1988 0.039 0.279 0.351 0.508 0.634 0.517 0.827 1989 0.118 0.258 0.378 0.508 0.660 0.716 1.073 1990 0.082 0.295 0.394 0.525 0.672 0.808 0.990 1991 0.093 0.317 0.420 0.534 0.603 0.823 1.168 1992 0.079 0.287 0.427 0.599 0.802 0.945 1.395 1993 0.169 0.334 0.460 0.592 0.689 0.878 1.167 1994 0.156 0.347 0.448 0.597 0.741 0.692 0.818 1995 0.167 0.323 0.449 0.578 0.714 0.763 0.780 1996 0.193 0.407 0.507 0.569 0.705 0.826 0.853 1997 0.093 0.369 0.510 0.659 0.806 1.071 1.511 1998 0.202 0.332 0.438 0.580 0.665 0.892 1.241 1999 0.079 0.314 0.435 0.562 0.782 0.951 1.317 2000 0.100 0.396 0.484 0.613 0.738 0.915 1.144 2001 0.102 0.419 0.506 0.636 0.796 1.053 1.259 36th SAW Consensus Summary 183
Table B1.14. Winter flounder NEFSC survey index stratified mean number and mean weight (kg) per tow for the Southern New England- Mid-Atlantic stock complex. Spring and fall strata set (offshore 1-12, 25, 69-76 ; inshore 1-29, 45-56); winter strata set (offshore 1-2, 5-6,9-10,69,73).
Spring Fall Year Number N(CV) Weight W(CV) Number N(CV) Weight W(CV) 1963 8.554 33.2 3.284 41.4 1964 13.673 22.1 4.894 19.4 1965 15.537 32.5 4.435 28.7 1966 9.843 31.5 3.275 27.3 1967 9.109 20.6 2.745 18.7 1968 2.444 26.7 0.734 37.2 8.105 21 2.19 18.7 1969 5.64 34.3 3.414 53.7 6.841 34.9 1.939 29.7 1970 2.729 30.9 1.326 35.6 5.11 36.1 2.375 47.8 1971 2.035 32.9 0.756 36.2 3.861 17.5 1.231 19.1 1972 1.865 28.1 0.656 32.1 7.687 39.4 3.053 44.6 1973 7.458 19.9 2.013 20.6 2.691 26.9 0.775 25.8 1974 3.362 21.9 1.043 19.3 2.032 31.1 0.822 29.4 1975 1.135 22.6 0.354 20.8 2.196 20.3 0.688 22.1 1976 3.085 16.3 0.804 17.2 2.376 32.2 1.251 42.9 1977 4.209 17.2 1.189 18.6 4.722 22.5 1.735 25.2 1978 6.695 11.1 1.758 13.3 3.743 17.6 1.43 22.6 1979 2.966 16.8 1.069 25 10.058 18.4 2.606 15.4 1980 15.25 17.5 3.551 13.6 9.964 31 3.216 29.5 1981 18.234 20.9 4.762 16.9 10.206 20.3 3.11 19.9 1982 6.986 20.1 1.918 15.8 4.927 22.8 1.683 25.9 1983 6.262 18.4 2.469 28 8.757 37.6 2.69 31.7 1984 5.524 19 2.072 28.4 2.681 21.1 0.887 21 1985 5.36 17.4 1.983 16.5 2.727 21.5 0.991 21.5 1986 2.266 23.9 0.766 23.4 1.538 21.9 0.487 19.1 1987 1.763 21.3 0.568 17.9 1.167 28.9 0.419 37.8 1988 2.126 19.6 0.73 19.3 1.246 22.4 0.53 27.5 1989 2.485 33.5 0.582 29.6 1.435 40.7 0.341 30.4 1990 1.992 36.8 0.472 33.1 1.979 29.6 0.546 25.8 1991 2.473 15.6 0.692 14.7 1.95 23.6 0.708 25.6 184 36th SAW Consensus Summary
Table B1.14 continued.
Spring Fall Winter Year Number N(CV) Weight W(CV) Number N(CV) Weight W(CV) Number N(CV) Weight W(CV) 1992 1.579 23.4 0.435 22.1 2.963 32.4 0.829 31.8 3.68 27.3 0.928 26 1993 0.961 19.1 0.219 14.8 1.382 25 0.392 25.9 2.59 29.4 0.456 21.5 1994 1.51 26.4 0.329 21.9 4.134 24.8 1.482 27.3 3.797 30.8 1.183 35.5 1995 2.097 23.4 0.592 19.1 2.253 20.7 0.626 17.3 2.221 26.1 0.697 29.1 1996 1.517 14.3 0.428 15.2 3.186 39.8 1.063 45.3 3.778 28.4 0.734 25.2 1997 1.436 22.1 0.399 20 7.893 32.6 2.583 26.7 3.906 19.7 1.043 21.6 1998 2.774 20.6 0.845 22.1 6.597 13.6 2.232 9.9 7.169 21.6 1.83 24.1 1999 4.171 16.2 1.245 16.4 3.596 17 1.549 16.5 10.328 31.8 3.1 32.3 2000 3.172 26.6 1.123 31.9 6.168 25.5 2.143 26.2 5.571 32.9 1.525 29.5 2001 1.568 14.3 0.581 13.3 4.877 28.1 2.03 28.5 3.096 31.6 0.873 29 2002 2.043 15.7 0.782 16.3 2.901 27.7 1.188 38.3 NOTE: 1968-1972 spring index does not include inshore strata ; 1963-1971 fall index does not include inshore strata. All indices calculated with trawl door conversion factors where appropriate. Winter trawl survey began in 1992.
36th SAW Consensus Summary 185
Table B1.15. SNE/MA winter flounder mean weight per tow for annual state surveys.
Year MADMF RIDFW RIDFW CTDEP NJDFW Spring Spring Fall Ocean (April) 1978 18.12 1979 18.17 7.72 7.24 1980 15.18 13.57 4.88 1981 15.77 12.13 2.12 1982 14.82 5.23 1.30 1983 19.67 9.52 2.28 1984 14.68 8.43 3.38 15.68 1985 11.60 5.93 3.01 13.82 1986 10.36 6.47 3.12 10.33 1987 9.57 8.14 2.25 11.76 1988 6.64 6.02 1.45 18.29 1989 8.46 3.09 0.79 22.62 5.86 1990 5.38 3.07 0.71 29.02 4.78 1991 2.91 7.38 0.18 24.59 5.32 1992 7.99 0.95 0.42 12.29 2.48 1993 8.16 0.22 0.50 10.26 3.87 1994 12.59 1.67 0.33 12.20 3.25 1995 7.98 6.04 0.89 7.72 8.06 1996 9.78 4.45 0.91 20.41 3.73 1997 10.02 4.57 0.64 15.53 6.52 1998 7.99 5.00 0.32 14.66 4.17 1999 4.44 3.66 0.57 10.29 6.83 2000 6.52 4.52 0.56 12.63 5.24 2001 3.73 3.56 0.28 14.02 6.36 2002 10.90 8.80 Mean 10.44 5.71 1.66 15.11 5.38 186 36th SAW Consensus Summary
Table B1.16. Winter flounder mean number per tow for annual state surveys.
Year MADMF RIDFW RIDFW CTDEP NYDEC NJDFW NJDFW Spring Spring Fall (Age-1) Ocean Rivers (April) (March-May) 1978 51.62 1979 53.78 83.76 1980 38.94 63.10 1981 46.12 87.97 25.21 1982 40.23 31.39 18.55 1983 56.84 58.97 17.29 1984 37.36 41.64 19.02 111.96 1985 38.38 34.97 21.44 83.05 1.96 1986 36.27 41.02 31.28 63.64 1987 37.85 56.21 20.90 79.92 1.64 1988 27.91 34.44 10.64 153.08 1.32 1989 24.41 20.88 7.17 150.08 3.01 25.60 1990 25.86 20.33 8.83 226.17 1.79 17.47 1991 10.66 41.95 1.77 156.06 3.38 22.17 1992 28.83 4.40 10.60 75.09 1.11 9.88 1993 46.96 2.92 6.65 69.60 5.42 20.13 1994 48.55 10.25 2.21 101.60 3.16 14.16 1995 37.84 32.19 7.00 62.62 1.72 30.04 3.00 1996 30.18 20.67 7.79 129.82 1.32 9.60 3.30 1997 39.31 22.28 5.48 78.79 3.15 36.24 3.60 1998 34.63 19.22 2.02 82.21 3.80 18.05 4.90 1999 25.11 13.45 2.80 50.05 3.25 17.84 3.20 2000 26.23 16.32 2.58 49.74 1.56 10.13 2.60 2001 16.00 12.49 2.10 55.80 5.52 13.83 2.90 2002 43.74 22.72 Mean 35.83 33.51 11.02 95.95 2.69 19.13 3.36 36th SAW Consensus Summary 187
Table B1.17. State survey indices (stratified mean number per tow or haul) for young-of-year winter flounder in Southern New England/Mid-Atlantic stock complex.
Year MADMF RIDFW CTDEP NYDEC DEDFG Seine Seine 1975 0.30 1976 0.32 1977 0.60 1978 0.34 1979 0.49 1980 0.40 1981 0.32 1982 0.37 1983 0.23 1984 0.32 1985 0.34 0.75 1986 0.32 29.00 0.17 1987 0.27 11.60 0.97 0.09 1988 0.18 8.90 15.50 0.69 0.02 1989 0.42 18.90 1.90 1.67 0.29 1990 0.33 22.10 3.10 2.71 0.63 1991 0.27 12.00 5.80 2.57 0.03 1992 0.29 33.20 13.70 11.49 0.27 1993 0.07 5.50 6.00 4.73 0.04 1994 0.15 2.60 16.60 2.44 0.31 1995 0.16 5.30 12.50 0.91 0.10 1996 0.22 2.80 19.20 3.80 0.04 1997 0.39 4.40 7.47 4.42 1998 0.16 2.50 9.38 3.11 1999 0.19 14.60 8.70 7.49 2000 0.33 52.90 4.30 0.90 2001 0.21 12.90 1.30 2.31 2002 0.10 Mean 0.27 14.95 8.96 3.19 0.18 188 36th SAW Consensus Summary
Table B1.18. NEFSC Spring survey: stratified mean number per tow at age for winter flounder in the Southern New England/Mid-Atlantic stock complex (strata set: offshore 1-12, 5, 69-76; inshore 1-29, 45-56).
Age Year 1 2 3 4 5 6 7 8 9+ Total 1980 2.19 8.21 4.15 0.51 0.15 0.04 15.25 1981 2.00 8.08 6.89 0.95 0.26 0.02 0.03 18.23 1982 1.16 3.20 1.56 0.74 0.21 0.09 0.02 0.01 6.99 1983 0.58 0.97 2.14 1.23 0.81 0.37 0.08 0.08 6.26 1984 0.22 1.36 2.18 0.85 0.46 0.29 0.07 0.06 0.03 5.52 1985 0.41 1.21 2.16 0.72 0.51 0.20 0.14 0.01 5.36 1986 0.10 0.49 1.16 0.31 0.15 0.05 0.01 2.27 1987 0.14 0.54 0.70 0.28 0.06 0.02 0.01 0.01 1.76 1988 0.09 0.48 0.99 0.37 0.16 0.02 0.02 2.13 1989 0.14 0.95 0.90 0.34 0.11 0.02 0.02 0.01 2.49 1990 0.23 0.49 0.89 0.28 0.05 0.04 0.01 1.99 1991 0.14 0.60 1.22 0.41 0.05 0.02 0.02 0.01 2.47 1992 0.14 0.39 0.62 0.36 0.05 0.02 1.58 1993 0.14 0.35 0.26 0.12 0.07 0.01 0.01 0.96 1994 0.16 0.74 0.43 0.11 0.04 0.02 0.01 1.51 1995 0.22 0.75 0.87 0.22 0.03 0.01 2.10 1996 0.07 0.54 0.66 0.17 0.06 0.01 0.01 1.52 1997 0.13 0.50 0.56 0.18 0.06 0.01 1.44 1998 0.33 1.21 0.72 0.37 0.13 0.01 2.77 1999 0.41 1.89 1.35 0.36 0.11 0.04 0.01 4.17 2000 0.28 0.70 1.19 0.65 0.27 0.07 0.01 3.17 2001 0.17 0.26 0.47 0.44 0.20 0.02 0.01 1.57 2002 0.11 0.60 0.56 0.38 0.23 0.11 0.04 0.01 2.04 Mean 0.42 1.50 1.42 0.45 0.18 0.07 0.03 0.03 0.02 4.07 36th SAW Consensus Summary 189
Table B1.19. NEFSC Fall survey: stratified mean number per tow at age for winter flounder in the Southern New England/Mid-Atlantic stock complex (strata set: offshore 1-12, 5, 69-76; inshore 1-29, 45-56).
Age Year 0 1 2 3 4 5 6 7 8+ Total 1980 0.40 1.76 4.62 2.74 0.44 0.01 0.01 9.98 1981 0.01 2.06 5.05 2.30 0.31 0.06 0.08 0.03 9.90 1982 0.01 0.76 2.21 1.34 0.47 0.12 0.02 4.93 1983 1.63 3.82 2.06 0.62 0.35 0.11 0.07 0.10 8.76 1984 0.17 1.04 1.17 0.26 0.03 0.01 2.68 1985 0.16 1.18 0.99 0.30 0.09 0.01 2.73 1986 0.23 0.90 0.36 0.03 0.01 0.01 1.54 1987 0.03 0.64 0.36 0.12 0.02 1.17 1988 0.03 0.30 0.64 0.22 0.04 0.01 0.01 1.25 1989 0.28 0.83 0.26 0.05 0.01 0.01 1.44 1990 0.08 0.89 0.85 0.15 0.01 1.98 1991 0.07 1.02 0.73 0.12 0.01 1.95 1992 0.13 1.74 0.79 0.26 0.03 0.01 2.96 1993 0.43 0.52 0.35 0.08 1.38 1994 0.45 2.23 1.08 0.30 0.04 0.03 4.13 1995 0.58 0.93 0.63 0.09 0.01 0.01 2.25 1996 0.61 1.40 0.80 0.31 0.06 0.01 3.19 1997 1.48 3.58 2.20 0.55 0.08 7.89 1998 1.39 2.83 1.91 0.41 0.05 0.01 6.60 1999 0.43 0.95 1.46 0.54 0.18 0.04 3.60 2000 0.90 2.30 2.02 0.71 0.22 0.01 0.01 6.17 2001 0.49 1.79 1.61 0.63 0.30 0.02 0.04 4.88 2002 Mean 0.64 1.85 1.21 0.32 0.08 0.03 0.03 0.10 4.26 190 36th SAW Consensus Summary
Table B1.20. NEFSC Winter survey: stratified mean number per tow at age for winter flounder in the Southern New England/Mid-Atlantic stock complex (strata set: offshore 1-2, 5-6, 9-10,69, 73).
Age Year 1 2 3 4 5 6 7 8+ Total 1992 0.73 0.86 1.09 0.73 0.24 0.02 0.02 3.68 1993 0.56 1.16 0.54 0.18 0.12 0.02 0.01 2.59 1994 0.36 1.16 1.76 0.25 0.28 3.80 1995 0.04 0.75 1.26 0.17 2.22 1996 1.01 0.87 1.55 0.32 0.02 3.78 1997 0.43 1.49 1.32 0.54 0.13 3.91 1998 0.42 3.52 1.95 0.96 0.32 7.17 1999 0.84 5.94 2.23 0.96 0.20 0.16 10.33 2000 0.23 2.82 2.12 0.24 0.16 5.57 2001 1.04 0.55 0.70 0.54 0.22 0.05 3.10 2002 0.08 1.34 0.74 0.15 0.21 0.06 0.21 0.11 2.90 Mean 0.52 1.86 1.39 0.46 0.19 0.06 0.08 0.11 4.46 36th SAW Consensus Summary 191
Table B1.21. MADMF spring trawl survey mean number per tow at age for winter flounder in the Southern New England/Mid-Atlantic stock complex.
Age Year 1 2 3 4 5 6 7 8 9+ Total 1978 9.93 9.73 15.74 9.33 3.15 1.09 1.33 0.51 0.81 51.62 1979 4.63 12.92 21.14 8.90 2.93 1.00 0.95 0.46 0.85 53.78 1980 1.63 8.21 14.50 9.13 3.01 0.96 0.79 0.28 0.43 38.94 1981 8.35 8.75 13.17 9.38 3.68 1.16 0.75 0.32 0.56 46.12 1982 3.22 11.13 12.36 8.62 2.61 1.05 0.67 0.15 0.42 40.23 1983 1.68 14.84 17.42 13.87 4.08 2.31 1.18 0.56 0.90 56.84 1984 1.17 9.34 11.62 10.06 3.32 1.22 0.48 0.01 0.14 37.36 1985 2.96 9.53 16.09 6.30 2.44 0.73 0.24 0.02 0.07 38.38 1986 3.23 6.81 19.13 5.64 0.82 0.12 0.18 0.16 0.18 36.27 1987 9.29 7.44 11.68 6.46 2.02 0.43 0.35 0.08 0.10 37.85 1988 3.21 7.22 14.45 2.41 0.34 0.08 0.17 0.00 0.03 27.91 1989 2.09 5.41 11.39 4.52 0.96 0.28 0.27 0.12 0.37 25.41 1990 4.22 10.66 7.60 2.90 0.32 0.05 0.10 0.01 25.86 1991 1.64 2.79 4.68 1.15 0.23 0.12 0.02 0.03 10.66 1992 7.93 7.55 6.68 4.16 1.64 0.59 0.07 0.08 0.13 28.83 1993 14.17 17.56 11.70 2.71 0.62 0.14 0.02 0.04 46.96 1994 11.48 16.12 14.65 4.66 0.61 0.58 0.37 0.05 0.03 48.55 1995 13.82 12.05 8.17 1.92 0.60 0.80 0.28 0.14 0.06 37.84 1996 4.81 9.73 7.61 2.84 1.99 1.45 0.84 0.29 0.62 30.18 1997 10.34 10.06 10.38 4.26 1.32 1.01 0.49 0.75 0.70 39.31 1998 8.17 12.59 6.92 3.51 1.46 1.22 0.41 0.31 0.04 34.63 1999 9.23 7.91 5.59 1.79 0.20 0.23 0.13 0.03 25.11 2000 6.62 8.94 6.95 1.69 1.05 0.48 0.22 0.25 0.03 26.23 2001 5.21 5.17 2.46 2.03 0.63 0.19 0.14 0.13 0.04 16.00 Mean 6.21 9.69 11.34 5.34 1.67 0.72 0.44 0.22 0.30 35.87 192 36th SAW Consensus Summary
Table B1.22. CTDEP spring survey for winter flounder in the Southern New England/Mid Atlantic stock complex.
Age Year 0 1 2 3 4 5 6 7 8 9 10 11 12 Total 1984 - 8.21 44.50 31.47 20.83 4.23 1.23 0.67 0.74 0.04 0.01 0.03 0.00 111.96 1985 - 4.10 28.28 32.57 14.13 2.33 0.83 0.45 0.19 0.11 0.04 0.02 0.00 83.05 1986 - 6.69 25.91 15.62 12.27 2.04 0.50 0.25 0.24 0.09 0.01 0.02 0.00 63.64 1987 - 7.32 44.69 14.56 5.05 6.55 1.29 0.11 0.24 0.11 0.00 0.00 0.00 79.92 1988 15.50 14.49 71.87 39.10 8.60 1.82 1.45 0.17 0.04 0.02 0.02 0.00 0.00 153.08 1989 1.90 13.57 78.42 41.23 10.85 2.84 0.98 0.13 0.09 0.06 0.01 0.00 0.00 150.08 1990 3.10 11.31 131.52 64.97 8.97 4.08 1.96 0.19 0.05 0.00 0.02 0.00 0.00 226.17 1991 5.80 8.66 66.88 60.41 9.31 4.05 0.80 0.13 0.01 0.00 0.00 0.01 0.00 156.06 1992 13.70 6.80 31.32 12.78 8.98 1.10 0.36 0.05 0.00 0.00 0.00 0.00 0.00 75.09 1993 6.00 19.11 19.87 15.46 4.81 3.24 0.79 0.15 0.12 0.04 0.01 0.00 0.00 69.60 1994 16.60 9.54 64.06 5.90 3.06 1.15 0.50 0.17 0.06 0.01 0.01 0.00 0.00 101.06 1995 12.50 14.35 23.69 9.77 1.36 0.63 0.20 0.08 0.02 0.02 0.00 0.00 0.00 62.62 1996 19.20 11.46 59.07 24.17 14.41 0.98 0.29 0.13 0.06 0.04 0.01 0.00 0.00 129.82 1997 7.47 12.53 25.53 19.41 9.45 3.76 0.51 0.07 0.03 0.01 0.01 0.01 0.00 78.79 1998 9.28 11.30 32.48 12.18 12.60 3.09 1.05 0.15 0.01 0.07 0.00 0.00 0.00 82.21 1999 8.70 6.53 12.42 11.29 6.09 3.21 1.13 0.61 0.04 0.01 0.02 0.00 0.00 50.05 2000 4.30 7.11 16.66 8.40 7.70 3.44 1.53 0.31 0.26 0.01 0.01 0.00 0.01 49.74 2001 1.30 8.37 19.65 10.87 8.06 5.46 1.26 0.70 0.04 0.09 0.00 0.00 0.00 55.80 2002 0.00 Mean 8.95 10.08 44.27 23.90 9.25 3.00 0.93 0.25 0.12 0.04 0.01 0.01 0.00 100.81 36th SAW Consensus Summary 193
Table B1.23. RIDFW spring survey for winter flounder in the Southern New England-Mid Atlantic stock complex.
Age Year 1 2 3 4 5 6 7+ Total 1981 13.55 32.2 32.99 6.07 1.85 0.79 0.48 87.93 1982 10.59 10.28 6.24 3.21 0.74 0.12 0.14 31.32 1983 16.75 18.51 11.63 7.61 1.9 0.84 0.25 57.49 1984 3.31 21.97 10.46 4.17 1.19 0.3 0.08 41.48 1985 3.77 13.42 14.19 2.44 0.81 0.07 0.04 34.74 1986 9.65 14.16 12.5 3.79 0.57 0.04 0.08 40.79 1987 12.44 20.56 17.09 4.24 0.91 0.14 0.09 55.47 1988 7.33 12.05 10.97 2.94 0.36 0 0.02 33.67 1989 6.67 6.32 5.55 1.58 0.32 0.1 0.03 20.57 1990 5.73 7.63 4.51 2.09 0.19 0.03 0.05 20.23 1991 12.48 14.67 11.29 2.14 0.48 0.22 0.02 41.30 1992 1.19 1.36 1.13 0.51 0.18 0.03 0 4.40 1993 2.35 0.26 0.18 0.05 0.01 0 0 2.85 1994 2.87 4.74 1.9 0.59 0.08 0.02 0.01 10.21 1995 8.33 9.53 11.22 2.03 0.43 0.45 0.2 32.19 1996 2.11 6.45 4.07 1.42 0.53 0.25 0.11 14.94 1997 4.47 7.79 7.42 1.69 0.45 0.25 0.18 22.25 1998 1.5 4.16 8.43 3.87 0.7 0.46 0.11 19.23 1999 1.61 4.07 5.45 1.84 0.16 0.16 0.13 13.42 2000 2.99 4.91 6.09 1.32 0.65 0.20 0.12 16.28 2001 2.11 4.23 2.89 2.53 0.57 0.04 0.08 12.45 Mean 6.28 10.44 8.87 2.67 0.62 0.21 0.11 29.20 194 36th SAW Consensus Summary
Table B1.24. NJDFW Ocean survey (April) for winter flounder in the Southern New England/Mid-Atlantic stock complex. Lengths for 2002 aged with the 2001 age-length key.
Age Year 1 2 3 4 5 6 7+ Total 1993 5.1 6.5 2.5 2.4 1.7 0.4 0.57 19.17 1994 3.7 4.2 3.9 1.4 0.4 0.3 0.16 14.06 1995 8 10.1 8.6 2.4 0.9 0.3 0.11 30.41 1996 0.6 2.9 2.6 1.9 0.9 0.3 0.2 9.40 1997 16.6 5.4 6.1 6 1.5 0.3 0.12 36.02 1998 4.5 3.9 4.8 3.3 1.2 0.4 0.1 18.20 1999 2.40 2.20 5.90 3.10 2.90 0.70 0.59 17.79 2000 0.70 0.30 2.10 3.30 2.00 0.90 0.80 10.10 2001 3.90 0.60 1.30 2.70 3.80 0.70 0.83 13.83 2002 7.56 3.67 3.30 3.00 3.67 0.76 0.77 22.73 Mean 5.06 4.01 4.20 2.94 1.70 0.48 0.39 18.78 36th SAW Consensus Summary 195
Table B1.25. NJDFW Rivers survey (March-May) for winter flounder in the Southern New England/Mid Atlantic stock complex.
Age Year 1 2 3 4 5 6 7+ Total 1995 0.6 0.3 1.4 0.4 0.1 0.01 0.01 2.82 1996 0.3 0.9 0.7 0.7 0.2 0.1 0.15 3.05 1997 1.1 0.4 0.9 0.4 0.4 0.1 0.05 3.35 1998 1.9 0.9 0.4 0.7 0.2 0.1 0.05 4.25 1999 0.20 0.50 1.40 0.50 0.40 0.10 0.13 3.23 2000 0.40 0.20 0.40 0.80 0.20 0.10 0.01 2.11 2001 1.40 0.30 0.20 0.40 0.40 0.10 0.04 2.84 Mean 0.84 0.50 0.77 0.56 0.27 0.09 0.06 3.09 196 36th SAW Consensus Summary
Table B1.26. Virtual Population Analysis for SNE/MA winter flounder, 1981-2001.
Fisheries Assessment Toolbox SNE/MA Winter Flounder Run Number W36_2 9/25/2002 1:11:40 PM FACT Version 1.5.0 SNE/MA Winter Flounder 1981 - 2002 Input Parameters and Options Selected Natural mortality is a matrix below Oldest age (not in the plus group) is 6 For all years prior to the terminal year ( 21 ), backcalculated stock sizes for the following ages used to estimate total mortality (Z) for age 6 : 4 5 6 This method for estimating F on the oldest age is generally used when a flat-topped partial recruitment curve is thought to be characteristic of the stock.
Stock size of the 7 + group is then calculated using the following method: CATCH EQUATION Partial recruitment estimate for 2002 1 0.01 2 0.2 3 0.6 4 1 5 1 6 1 The Indices that will be used in this run are:
1 NEC_S1 2 NEC_S2 3 NEC_S3 4 NEC_S4 5 NEC_S5 6 NEC_S6 7 NEC_S7 8 NEC_F2 9 NEC_F3 10 NEC_F4 11 NEC_W1 12 NEC_W2 13 NEC_W3 14 NEC_W4 15 NEC_W5 16 MA_S2 17 MA_S3 18 MA_S4 19 MA_S5 20 RI_S1 21 RI_S2 22 RI_S3 23 RI_S4 24 CT_S1 25 CT_S2 26 CT_S3 27 CT_S4 28 CT_S5 29 CT_S6 30 CT_S7 31 MA_YOY1 32 CT_YOY1 33 NY_PB1.1 34 NJ_O3 35 NJ_O4 36 NJ_O5 37 NJ_O6 38 NJ_O7 39 NJ_R1 40 NJ_R2 41 NJ_R3 42 NJ_R4 43 NJ_R5 36th SAW Consensus Summary 197
Table B1.26 continued.
STOCK NUMBERS (Jan 1) in thousands 1981 1982 1983 1984 1985 1986 1987 1 62859 52020 56503 35617 34615 32795 25973 2 52566 50232 42060 45703 28708 28090 26656 3 27768 30289 28226 27884 26945 16839 17273 4 7146 9748 13560 11068 10077 10446 5551 5 1468 2600 4606 5559 4603 2773 4738 6 363 600 1577 2148 2944 1096 1317 7 218 564 1219 1949 2228 876 730 1+ 152388 146054 147751 129927 110120 92914 82238 1988 1989 1990 1991 1992 1993 1994 1 26726 23113 17366 11355 7808 8844 8315 2 21199 21806 18504 14185 9249 6370 6993 3 17057 13790 13106 13242 8875 6212 3350 4 6000 5458 4798 5053 4381 3233 2074 5 1748 1325 1299 1276 1111 1251 1084 6 1433 339 317 369 268 300 495 7 433 312 223 165 86 218 300 1+ 74596 66142 55613 45645 31778 26429 22611 1995 1996 1997 1998 1999 2000 2001 1 12647 17632 21154 18793 13372 12710 19011 2 6753 10333 14407 16971 15341 10889 10343 3 4733 5352 7658 9864 11966 10076 7610 4 1700 2190 3070 3284 4761 6170 5082 5 1053 588 791 875 1063 2320 2830 6 606 487 171 159 254 456 1120 7 433 312 73 228 83 168 512 1+ 27925 36893 47324 50174 46840 42788 46509 2002 1 5665 2 15553 3 6671 4 2912 5 2179 6 1602 7 1057 1+ 35639 198 36th SAW Consensus Summary
Table B1.26 continued.
FISHING MORTALITY 1981 1982 1983 1984 1985 1986 1987 1 0.02 0.01 0.01 0.02 0.01 0.01 0.00 2 0.35 0.38 0.21 0.33 0.33 0.29 0.25 3 0.85 0.60 0.74 0.82 0.75 0.91 0.86 4 0.81 0.55 0.69 0.68 1.09 0.59 0.96 5 0.69 0.30 0.56 0.44 1.23 0.54 1.00 6 0.81 0.50 0.67 0.60 1.18 0.59 1.00 7 0.81 0.50 0.67 0.60 1.18 0.59 1.00 1988 1989 1990 1991 1992 1993 1994 1 0.00 0.02 0.00 0.01 0.00 0.03 0.01 2 0.23 0.31 0.13 0.27 0.20 0.44 0.19 3 0.94 0.86 0.75 0.91 0.81 0.90 0.48 4 1.31 1.24 1.12 1.31 1.05 0.89 0.48 5 1.44 1.23 1.06 1.36 1.11 0.73 0.38 6 1.41 1.29 1.15 1.39 1.10 0.86 0.45 7 1.41 1.29 1.15 1.39 1.10 0.86 0.45 1995 1996 1997 1998 1999 2000 2001 1 0.00 0.00 0.02 0.00 0.01 0.01 0.00 2 0.03 0.10 0.18 0.15 0.22 0.16 0.24 3 0.57 0.36 0.65 0.53 0.46 0.48 0.76 4 0.86 0.82 1.06 0.93 0.52 0.58 0.65 5 0.57 1.04 1.40 1.04 0.65 0.53 0.37 6 0.76 0.88 1.16 0.98 0.55 0.57 0.23 7 0.76 0.88 1.16 0.98 0.55 0.57 0.23 Average F for 4,5 1981 1982 1983 1984 1985 1986 1987 4,5 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1988 1989 1990 1991 1992 1993 1994 4,5 1.38 1.23 1.09 1.34 1.08 0.81 0.43 1995 1996 1997 1998 1999 2000 2001 4,5 0.72 0.93 1.23 0.98 0.58 0.55 0.51 Biomass Weighted F 1981 1982 1983 1984 1985 1986 1987 0.47 0.42 0.38 0.47 0.61 0.44 0.58 1988 1989 1990 1991 1992 1993 1994 0.67 0.56 0.48 0.68 0.64 0.60 0.28 1995 1996 1997 1998 1999 2000 2001 0.30 0.23 0.42 0.31 0.36 0.37 0.39 36th SAW Consensus Summary 199
Table B1.26 continued.
BACK-CALCULATED PARTIAL RECRUITMENT 1981 1982 1983 1984 1985 1986 1987 1 0.03 0.02 0.02 0.02 0.01 0.01 0.00 2 0.41 0.62 0.29 0.40 0.27 0.31 0.25 3 1.00 1.00 1.00 1.00 0.61 1.00 0.85 4 0.96 0.91 0.94 0.83 0.88 0.65 0.95 5 0.82 0.50 0.76 0.53 1.00 0.60 0.99 6 0.95 0.82 0.91 0.73 0.95 0.65 1.00 7 0.95 0.82 0.91 0.73 0.95 0.65 1.00 1988 1989 1990 1991 1992 1993 1994 1 0.00 0.02 0.00 0.00 0.00 0.04 0.02 2 0.16 0.24 0.12 0.19 0.18 0.49 0.40 3 0.65 0.66 0.65 0.65 0.73 1.00 1.00 4 0.91 0.96 0.98 0.95 0.95 1.00 1.00 5 1.00 0.95 0.92 0.98 1.00 0.81 0.80 6 0.98 1.00 1.00 1.00 0.99 0.96 0.94 7 0.98 1.00 1.00 1.00 0.99 0.96 0.94 1995 1996 1997 1998 1999 2000 2001 1 0.00 0.00 0.01 0.00 0.01 0.01 0.00 2 0.04 0.10 0.13 0.14 0.34 0.27 0.31 3 0.66 0.34 0.46 0.51 0.71 0.84 1.00 4 1.00 0.79 0.75 0.89 0.80 1.00 0.85 5 0.66 1.00 1.00 1.00 1.00 0.91 0.48 6 0.88 0.85 0.83 0.94 0.85 0.99 0.31 7 0.88 0.85 0.83 0.94 0.85 0.99 0.31 MEAN BIOMASS (using catch mean weights at age) 1981 1982 1983 1984 1985 1986 1987 1 7320 4218 9928 4678 3468 3821 1081 2 11153 9965 8174 9159 6274 6496 6171 3 8228 9117 6470 6403 6338 4048 4094 4 3606 4760 4630 3994 2728 3465 1813 5 1033 2144 2494 2851 1276 1340 1313 6 284 541 1102 1350 747 666 432 7 165 745 1264 1720 742 582 362 1+ 31790 31490 34061 30156 21572 20418 15266 1988 1989 1990 1991 1992 1993 1994 1 943 2445 1289 955 558 1332 1171 2 4807 4409 4639 3590 2190 1570 2009 3 3573 3219 3329 3364 2386 1735 1090 4 1573 1472 1396 1390 1496 1164 899 5 544 465 497 390 497 562 609 6 369 126 140 152 142 162 252 7 178 174 121 97 67 157 180 1+ 11987 12310 11412 9937 7335 6682 6210 1995 1996 1997 1998 1999 2000 2001 1 1912 3081 1766 3436 955 1149 1757 2 1946 3634 4425 4755 3933 3624 3508 3 1482 2082 2635 3068 3806 3532 2475 4 605 782 1152 1142 1908 2627 2180 5 524 238 318 334 561 1216 1718 6 298 246 100 84 170 290 957 7 218 163 60 166 77 134 523 1+ 6984 10225 10456 12985 11410 12571 13118 200 36th SAW Consensus Summary
Table B1.26 continued.
SSB AT THE START OF THE SPAWNING SEASON -MALES AND FEMALES (MT) (using SSB mean weights) 1981 1982 1983 1984 1985 1986 1987 1 00 00 00 00 00 00 00 2 00 00 00 00 00 00 00 3 4739 4757 3771 3557 3615 2395 2482 4 3893 4592 5119 3855 3106 3541 1958 5 1205 2157 2899 2927 1838 1374 1779 6 341 603 1387 1540 1272 634 644 7 214 900 1590 2129 1037 718 489 1+ 10393 13009 14766 14008 10869 8662 7353 1988 1989 1990 1991 1992 1993 1994 1 00 00 00 00 00 00 00 2 00 00 00 00 00 00 00 3 2282 1923 1831 1980 1414 960 600 4 1863 1642 1556 1627 1626 1242 902 5 744 576 590 526 559 667 639 6 516 169 177 200 156 203 300 7 260 248 169 140 93 206 215 1+ 5663 4559 4323 4474 3848 3278 2656 1995 1996 1997 1998 1999 2000 2001 1 00 00 00 00 00 00 00 2 00 00 00 00 00 00 00 3 849 1028 1563 1817 2128 1756 2579 4 665 857 1311 1354 1990 2548 2103 5 589 293 389 452 563 1251 1692 6 376 301 113 107 170 296 715 7 279 214 84 224 73 169 553 1+ 2759 2693 3459 3954 4923 6021 7643 36th SAW Consensus Summary 201
Table B1.26 continued.
Fishing Mortality Terminal Year 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1997 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1.37 1.23 1.08 1.31 1.02 0.71 0.34 0.50 0.47 0.37 1998 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1.38 1.23 1.09 1.33 1.05 0.76 0.38 0.60 0.65 0.54 0.32 1999 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1.38 1.23 1.09 1.33 1.07 0.79 0.41 0.65 0.76 0.77 0.38 0.36 2000 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1.38 1.23 1.09 1.34 1.08 0.81 0.42 0.71 0.89 1.10 0.74 0.39 0.59 2001 0.75 0.42 0.63 0.56 1.16 0.57 0.98 1.38 1.23 1.09 1.34 1.08 0.81 0.43 0.72 0.93 1.23 0.98 0.58 0.55 0.51 Spawning Stock Biomass Terminal Year 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1997 10393 13009 14767 14009 10869 8663 7354 5666 4566 4343 4548 4038 3670 3273 3849 4826 7444 1998 10393 13009 14766 14008 10869 8662 7354 5664 4562 4331 4505 3929 3445 2919 3220 3833 6041 7845 1999 10393 13009 14766 14008 10869 8662 7354 5664 4561 4327 4488 3887 3355 2783 2969 3357 5233 6245 7280 2000 10393 13009 14766 14008 10869 8662 7354 5663 4560 4323 4477 3856 3295 2681 2807 2781 3971 4866 5537 6897 2001 10393 13009 14766 14008 10869 8662 7353 5663 4559 4323 4474 3848 3278 2656 2759 2693 3459 3954 4923 6021 7643 Population Numbers Age: 1 Terminal Year 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1997 62859 52021 56504 35618 34618 32804 26001 26802 23425 17857 12277 8527 11725 13557 19744 19471 31502 21889 1998 62859 52021 56504 35617 34617 32799 25985 26759 23243 17580 11733 8140 9992 12293 17810 18933 27084 31936 31205 1999 62859 52021 56504 35617 34616 32797 25979 26743 23169 17482 11501 8036 9204 11387 16304 17649 22197 21574 17992 15496 2000 62859 52020 56503 35617 34616 32795 25975 26729 23127 17384 11400 7826 8998 8449 15177 17596 20214 19212 13851 13085 15615 2001 62859 52020 56503 35617 34615 32795 25973 26726 23113 17366 11355 7808 8844 8315 12647 17632 21154 18793 13372 12710 19011 202 36th SAW Consensus Summary
Table B1.27. VPA Bootstrap results: precision of estimates.
The number of bootstraps: 500 Bootstrap Output Variable: N hat NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN N 1 5665 5960 1905 0.34 N 2 15553 15895 3191 0.21 N 3 6671 6691 1176 0.18 N 4 2912 2938 648 0.22 N 5 2179 2208 504 0.23 N 6 1602 1631 369 0.23 N 7 726 736 159 0.22 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI N 1 294 85 5.20 5371 0.354683 3746 8342 N 2 342 143 2.20 15211 0.209761 11856 19828 N 3 21 53 0.31 6650 0.176795 5097 8050 N 4 26 29 0.90 2886 0.224561 2114 3811 N 5 29 23 1.35 2149 0.234726 1611 2910 N 6 28 16 1.78 1574 0.234188 1158 2114 N 7 10 07 1.42 715 0.221624 534 937 Bootstrap Output Variable: F t NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN Age 1 0.0008 0.0008 0.0002 0.21 Age 2 0.2386 0.2440 0.0395 0.17 Age 3 0.7607 0.7755 0.1236 0.16 Age 4 0.6471 0.6599 0.1136 0.18 Age 5 0.3689 0.3773 0.0754 0.20 Age 6 0.2336 0.2397 0.0491 0.21 Age 7 0.2336 0.2397 0.0491 0.21 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI Age 1 0.0000137 0.0000070 1.815 0.0007423 0.21 0.0006 0.0010 Age 2 0.0053697 0.0017644 2.250 0.2332777 0.17 0.2014 0.3004 Age 3 0.0147454 0.0055258 1.938 0.7459918 0.17 0.6241 0.9413 Age 4 0.0128214 0.0050816 1.981 0.6342562 0.18 0.5193 0.8015 Age 5 0.0084273 0.0033716 2.285 0.3604493 0.21 0.2905 0.4802 Age 6 0.0061558 0.0021967 2.635 0.2274158 0.22 0.1853 0.3045 Age 7 0.0061558 0.0021967 2.635 0.2274158 0.22 0.1853 0.3045 Bootstrap Output Variable: SSB spawn t NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN 7642.6469 7705.3234 658.0444 0.09 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI 62.68 29.43 0.82 7579.97 0.09 6777.3392 8444.6451 36th SAW Consensus Summary 203
Table B1.28. Input parameters and stochastic projection results for winter flounder in the Southern New England/Mid-Atlantic stock complex. Starting stock sizes for ages 1 and older on January 1, 2002 are as estimated by SARC 36 VPA, and are not adjusted for the retrospective pattern. Age-1 recruitment levels in 2003 and later years are estimated from a parametric stock-recruitment relationship estimated in NEFSC (2002). Fishing mortality was apportioned among landings and discard based on the proportion landed at age during 1998-2000. Mean weights at age (kg; spawning stock, mean stock biomass, landings, and discards) are weighted (by fishery) geometric means of 1998-2000 values.
Proportion of F, M before spawning = 0.20 (spawning peak on 1 March).
Age Stock Size Fishing Proportion Proportion Mean Weights Mean Weights Mean Weights on 1 Jan Mortality Landed Mature Spawning Landings Discards 2002 Pattern Stock (000s) 1 5688 0.02 0.02 0 0.07 0.325 0.116 2 15592 0.27 0.7 0 0.196 0.383 0.242 3 6712 0.75 0.91 0.53 0.387 0.465 0.317 4 2908 1 0.97 0.95 0.52 0.59 0.417 5 2170 1 0.97 1 0.637 0.725 0.868 6 1612 1 0.97 1 0.793 0.916 0.853 7+ 1064 1 0.97 1 1.144 1.125 1.402 F2002 is assumed 0.85*F2001 (15% decrease in F from 2001 to 2002); F during 2003-2013 as indicated; Forecast Medians (50% probability level) 2002 2003 2013 000 Metric tons F Land Disc SSB F Land Disc SSB F Land Disc SSB P (%) SSB > 30.1 kmt 0.43 3.0 0.2 5.9 Fsq=0.43 3.3 0.1 7.0 Fsq=0.43 8.0 0.5 16.4 0%
Fmsy=0.32 2.6 0.2 7.2 Fmsy=0.32 8.3 0.5 23.3 6%
Freb=0.24 2.0 0.1 7.3 Freb=0.24 8.1 0.4 30.1 50%
204 36th SAW Consensus Summary
SNE/MA Winter Flounder Landings and Discards 16000 14000 12000 Metric tons 10000 8000 6000 4000 2000 0
1960 1965 1970 1975 1980 1985 1990 1995 2000 Year Comm Land Comm Disc Rec Land Rec Disc Total Catch 1981-2001 Figure B1.1. Commercial landings (1964-2001), commercial discards (1981-2001) recreational landings (1981-2001), recreational discards (1981-2001) and total fishery catch (198-2001) for the SNE/MA winter flounder stock complex.
36th SAW Consensus Summary 205
SNE/MA winter flounder Total Catch Age Composition 1978 1980 1982 1984 1986 1988 Year 1990 1992 1994 1996 1998 2000 2002 0 1 2 3 4 5 6 7 8 Age Figure B1.2. Total catch age composition: 1981-2001 206 36th SAW Consensus Summary
2.0 1.8 1.6 1.4 Mean weight (kg)
Age 7+
1.2 Age 6 1.0 0.8 Age 5 Age 4 0.6 Age 3 0.4 Age 2 0.2 Age 1 0.0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year Figure B1.3. Trends in mean weight at age in the total catch of SNE/MA winter flounder.
36th SAW Consensus Summary 207
S N E /M A W in te r F lo u n d e r S u rv e y B io m a s s In d ic e s 6
N E F S C F a ll 5 N E F S C S p rin g 4 N E F S C W in te r 3
2 1
0 1960 1970 1980 1990 2000 Stratified mean kg/tow 20 M A D M F S p rin g R ID F W S p rin g 15 R ID F W F a ll 10 5
0 1960 1970 1980 1990 2000 30 C T D E P S p rin g 25 N JDFW O cean 20 15 10 5
0 1960 1970 1980 1990 2000 Year F ig u re B 1 .4 . T re n d s in re se arc h su rv ey b io m ass in d ice s fo r S N E /M A w in ter flo u n d er.
208 36th SAW Consensus Summary
S N E /M A W in te r F lo u n d e r R e c r u itm e n t In d ic e s 3
1 0
1975 1980 1985 1990 1995 2000 2005 Stratified mean no/tow 20 MA S1 RI S1 15 CT S1 10 5
0 1975 1980 1985 1990 1995 2000 2005 20 NJ O1 NY 1 15 NJ R1 10 5
0 1960 1970 1980 1990 2000 Year F ig u re B 1 .5 . T re n d s in su rv e y re c ru itm e n t in d ic e s fo r S N E /M A w in te r flo u n d e r.
In c lu d e s s p rin g s u rv e y a g e -1 in d ic e s a n d fa ll Y O Y in d ic e s a d v a n c e d o n e y e a r 36th SAW Consensus Summary 209
SNE/MA Winter Flounder Recruitment Indices 1.0 60 MA YOY no/tow MA YOY RI YOY no/tow 0.8 RI YOY 50 40 0.6 30 0.4 20 0.2 10 0.0 0 1975 1980 1985 1990 1995 2000 2005 Stratified mean no/tow 20 0.8 CT YOY DE YOY no/tow NY YOY 15 DE YOY 0.6 10 0.4 5 0.2 0 0.0 1975 1980 1985 1990 1995 2000 2005 Figure B1.5 continued.
210 36th SAW Consensus Summary
SNE/MA winter flounder VPA Sensitivity to Tuning Indices 1.0 W36_2 Final W36ALL Indices W36NEC Only 0.8 Fishing Mortality2001 W36STATE Only W36_1 W36_3 0.6 W36_28 W36_2IR 0.4 0.2 0.0 4 6 8 10 12 14 Spawning Stock Biomass2001 (thousand, mt)
Figure B1.6. Sensitivity of the SARC 36 VPA for SNE/MA winter flounder to alternative combination of survey tuning indices. Run W36_2 was selected as the final run.
36th SAW Consensus Summary 211
SNE/MA Winter Flounder Total Catch and Fishing Mortality 20 1.5 F (age 4-5) 15 Total Catch F (age 4-5) 1.0
'000 mt 10 0.5 5
Comm. Land.
0 0.0 1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B1.7. Total catch (landings and discards, '000 mt), commercial landings('000 mt), and fishing mortality rate (F, ages 4-5, unweighted) for SNE/MA winter flounder.
212 36th SAW Consensus Summary
SNE/MA Winter Flounder Precision of 2001 Estimates for SSB and F 100 15 90 Cumulative Probability Percent Frequency 80 70 10 60 50 40 5
30 20 10 0 0 0 5 10 15 Spawning Stock Biomass ('000 mt) 100 20 Cumulative Probability 90 Percent Frequency 80 15 70 60 50 10 40 30 5
20 10 0 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Fishing Mortality Rate Figure B1.8. Precision of estimates of spawning stock biomass (ages 3-7+, '000 mt) and fishing mortality rate (F, ages 4-5, unweighted) in 2001 for SNE/MA winter flounder.
Vertical bars display the range of the bootstrap estimates and the probability of individual values in the range. The solid curve gives the probability of SSB that is less or fishing mortality that is greater than any value along the X axis.
36th SAW Consensus Summary 213
SNE/MA Winter Flounder SSB and Recruitment 20 70 Recruitment (age 1, millions)
SSB 60 50 SSB ('000 mt) 40 10 Recruitment 30 20 10 0 0 1980 1985 1990 1995 2000 Recruitment Year Class, Biomass Year Figure B1.9. Spawning stock biomass (SSB, ages 3-7+, '000 mt) and recruitment (millions of fish at age-1) for SNE/MA winter flounder.
214 36th SAW Consensus Summary
SN E/M A w inter flounder retrospective V PA s 1.5 F (ages 4-5) 1.0 0.5 0.0 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 20 SSB (000s mt) 15 10 5
0 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Age-1 recruits (millions) 70 60 50 40 30 20 10 0
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Figure B1.10. Retrospective V PA s for SN E/M A w inter flounder.
36th SAW Consensus Summary 215
SNE/MA Winter Flounder Yield and SSB per Recruit 0.4 3.5 SSB per Recruit (kg)
YPR 3.0 Yield per Recruit (kg) 0.3 2.5 2.0 0.2 1.5 1.0 0.1 F40% SSB/R 0.5 0.0 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Fishing Mortality (F, age 4-5)
Figure B1.11. Yield per recruit (YPR) and spawning stock biomass per recruit (SSB/R) for SNE/MA winter flounder.
216 36th SAW Consensus Summary
SNE/MA Winter Flounder SSB - RECRUIT DATA FOR 1981-2001 YEAR CLASSES 100 90 80 70 60 82 MILLIONS 81 OF AGE 1 FISH 50 40 83 85 84 30 87 88 86 96 97 20 95 98 89 00 94 90 10 93 99 92 01 91 0
0 5 10 15 20 25 30 SSB ('000 mt)
Figure B1.12. SNE/MA winter flounder SARC 36 VPA SSB and recruit data for the 1981-2001 year classes. Curved line is the S-R function estimated by NEFSC (2002).
36th SAW Consensus Summary 217
SNE/MA Winter Flounder 35000 F2002 = 0.85*F2001 = 0.43 30000 SSBmsy = 30,100 mt 25000 Freb = 0.24 Fmsy = 0.32 SSB (mt) 20000 15000 10000 5000 0
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Year Figure B1.13. Median (50% probability) of forecast spawning stock biomass (SSB, mt) for SNE/MA winter flounder under Fmsy and Frebuild fishing mortality rates during 2003-2013. Assumes F2002 = 0.85*F2001 = 0.43.
218 36th SAW Consensus Summary
SNE/MA winter flounder sensitivity to hypothetical NEFSC survey index adjustments, 2000-2002 1.0
0.9 W36_2
Baseline 10% Increase 0.8 25% Increase 100% Increase 0.7 Fishing Mortality 0.6 0.5 0.4 0.3 Fmsy = 0.32 0.2 0.1 1/2 Bmsy = 15,050 mt 0.0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Spawning Stock Biomass2001 (thousand mt)
Figure B1.14. SNE/MA winter flounder VPA sensitivity to hypothetical NEFSC winter, spring, and fall survey index adjustments.
36th SAW Consensus Summary 219
SNE/MA Winter Flounder 1.4 91 88 1/2 SSBmsy SSBmsy 97 89 1.2 85 92 90 Fishing Mortality (F) 1.0 98 87 96 0.8 93 81 95 83 0.6 99 86 84 00 01 94 82 0.4 02 Fmsy 0.2 0.0 0 10 20 30 40 SSB ('000 mt)
Figure B1.15. SSB and F for SNE/MA winter flounder. NEFSC (2002) biological reference points (Fmsy = 0.32, SSBmsy = 30,100 mt) are also shown.
220 36th SAW Consensus Summary
B2. GULF OF MAINE (GOM) WINTER FLOUNDER TERMS OF REFERENCE The following terms of reference were addressed for Gulf of Maine winter flounder stock:
- 1) Characterize status of GM winter flounder using the analytical tools that are most appropriate for available data. These may include sequential population analysis, surplus production, survey indices and relative exploitation indices, or length based models.
- 2) Where possible provide best estimates of exploitation rates (fishing mortality, relative exploitation), mean biomass, spawning stock biomass and characterize uncertainty associated with these estimates.
- 3) Develop yield per recruit and biological reference points.
- 4) Where possible, provide short-term and medium term projections of catch and stock size under status quo F and various proposed target fishing mortality rates (F20%, F25%, F30%,
F40%, F0.01, Fmax, Fmsy) as appropriate.
- 5) Develop and recommend an overfishing definition for Gulf of Maine winter flounder that meets the standards of the Sustainable Fishery Act.
- 6) Develop research recommendations for improving assessment of winter flounder.
INTRODUCTION The last assessment for Gulf of Maine winter flounder was an index based assessment reviewed at SARC 21 (NEFSC 1996). Low indices and the absence of large fish in the survey led SARC 21 to conclude that the stock was overexploited in the mid 1990s. The current benchmark assessment is based on a Virtual Population Analysis (VPA) with commercial/recreational landings and discard estimates from 1982-2001 and research survey abundance indices from 1982-2002.
Winter flounder (Pleuronectes americanus) is a demersal flatfish species commonly found in estuaries and on the continental shelf. The species is distributed between the Gulf of St.
Lawrence and North Carolina, although it is not abundant south of Delaware Bay. Within the Gulf of Maine, winter flounder undergo migrations from estuaries, where spawning occurs in the late winter and spring, to offshore shelf areas of less than 60 fathoms. Winter flounder reach a maximum size of around 2.25 kg (5 pounds) and 65 cm, with the exception of Georges Bank where growth rate is higher and fish may reach a maximum weight up to 3.6 kg (8 pounds; Bigelow and Schroeder 1953).
36th SAW Consensus Summary 221
Current fishery management is coordinated by the ASMFC in state waters and the NEFMC in federal waters. Winter flounder fisheries in state waters have been managed by Interstate Agreement under the auspices of the ASMFC Fishery Management Plan (FMP) for Inshore Stocks of Winter Flounder since approval in May, 1992. The plan includes states from Delaware to Maine, with Delaware granted de minimus status (habitat regulations applicable but fishery management not required). The Plan's goal is to rebuild spawning stock abundance and achieve a fishing mortality-based management target of F40% (fishing rate that preserves 40% of the maximum spawning potential of the stock) in three steps: F25% in 1993-1994, F30% in 1995-1998, and F40% in 1999 and later years through implementation of compatible, state-specific regulations.
Coastal states from New Jersey to New Hampshire have promulgated a broad suite of indirect catch and effort controls. State agencies have set or increased minimum size limits for recreationally and commercially landed flounder (10-12 in and 12 in, respectively); enacted limited recreational closures and bag limits; and instituted seasonal, areal, or state-wide commercial landings/gear restrictions. Minimum codend mesh regulations have been promulgated in directed winter flounder fisheries: 6 in MA. New Hampshire prohibits the use of mobile gear in state waters with the exception of small mesh trawling in the shrimp fishery.
Winter flounder in the Exclusive Economic Zone (EEZ) are managed under the Northeast Multispecies Fishery FMP developed by the NEFMC. The principle catch of winter flounder in the EEZ has recently occurred as bycatch in directed trawl fisheries for Atlantic cod, haddock, and yellowtail flounder. The management unit encompasses the multispecies finfish fishery that operates from eastern Maine through Southern New England (72° 30'). At least one offshore stock, on Georges Bank, has been identified. The FMP extends authority over vessels permitted under the FMP even while fishing in state waters if federal regulations are more restrictive than the state regulations.
The Multispecies FMP was implemented in September, 1986, imposing a codend minimum mesh size of 5.5 in (previously 5.1 in) in the large-mesh regulatory area of Georges Bank and the offshore portion of Gulf of Maine. There were closed areas and seasons for haddock and yellowtail flounder. In the western Gulf of Maine, vessels were required to enroll in an Exempted Fisheries Program in order to target small-mesh species such as shrimp, dogfish, or whiting. The bycatch restrictions specified area and season and limited groundfish bycatch to 25% of trip and 10% for the reporting period. In southern New England waters, the groundfish bycatch on vessels fishing with small mesh was not limited in any way. There was a 11 in minimum size for winter flounder which corresponded with the length at first capture (near zero percent retention) for 5.5 in diamond mesh. Although the Multispecies FMP was amended four times by 1991, it was widely recognized that many stocks, including winter flounder, were being overfished.
Time-specific stock rebuilding schedules were a part of Multispecies FMP Amendment 5 which took effect in May, 1994. The rebuilding target for winter flounder, a so-called "large-mesh" species, was F20% within 10 years. Along with a moratorium on issuance of additional vessel permits, the cornerstone of Amendment 5 was an effort reduction program that required 222 36th SAW Consensus Summary
"large-mesh" groundfish vessels to limit days at sea, which would be reduced each year. There was an exemption from effort reduction requirements for groundfishing vessels less than 45 feet in length and for "day boats" (from 2:1 layover day ratio requirement). Draggers retaining more than the "possession limit" of groundfish (10%, by weight, up to 500 lbs) were required to fish with either 5.5 in diamond or square mesh in Southern New England or 6 in throughout the net in the regulated mesh area of Georges Bank/ Gulf of Maine, respectively. The possession limit was allowed when using small mesh within the western Gulf of Maine (except Jeffreys Ledge and Stellwagon Bank) and in Southern New England. Vessels fishing in the EEZ west of 72° 30' (the longitude of Shinnecock Inlet, NY) were required to abide by 5.5 in diamond or 6 in square codend mesh size restrictions consistent with the Summer Flounder FMP. The minimum landed size of winter flounder increased to 12 in, appropriate for the increased mesh size in order to reduce discards. There were many additional rules including time/area closures for sink gillnet vessels, seasonal netting closures of prime fishing areas on Georges Bank (Areas I and II), and on Nantucket Shoals to protect juvenile yellowtail flounder.
At the end of 1994, the NEFMC reacted to collapsed stocks of Atlantic cod, haddock, and yellowtail flounder on Georges Bank by recommending a number of emergency actions to tighten existing regulations reducing fishing mortality. Prime fishing areas on Georges Bank (Areas I &
II), and the Nantucket Lightship Area were closed. The NEFMC also addressed expected re-direction of fishing effort into Gulf of Maine and Southern New England while, at the same time, developing Amendment 7 to the Multispecies FMP. Under Amendment 7, days-at-sea controls were extended, and any fishing by an EEZ-permitted vessel required use of not less than 6 in diamond or square mesh in Southern New England east of 72° 30'. Framework 27 in 1999 increased the square mesh minimum size to 6.5 in in the Gulf of Maine, Georges Bank, and Southern New England mesh areas. Amendment 9 revised the overfishing definitions for New England groundfish, and new overfishing definitions for SNE/MA winter flounder were recommended by SARC 28 (NEFSC 1999).
STOCK STRUCTURE Although stock groups consist of an assemblage of adjacent estuarine spawning units, the ASMFC FMP originally defined three coastal management units based on similar growth, maturity and seasonal movement patterns: Gulf of Maine, Southern New England and the Mid-Atlantic. Boundaries for a total of four winter flounder stock units as originally defined in the ASMFC management plan (Howell et al., 1992) were:
Gulf of Maine: Coastal Maine, New Hampshire, and Massachusetts north of Cape Cod Southern New England: Coastal Massachusetts east and south of Cape Cod, including Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, Block Island Sound, Rhode Island Sound, Rhode Island coastal ponds and eastern Long Island Sound to the Connecticut River, including Fishers Island Sound, NY.
Mid-Atlantic: Long Island Sound west of the Connecticut River to Montauk Point, NY, 36th SAW Consensus Summary 223
including Gardiners and Peconic Bays, coastal Long Island, NY, coastal New Jersey and Delaware.
Georges Bank In the current and previous assessments (e.g., NEFSC 1996, ASMFC 1998, NEFSC 1999) the Southern New England and Mid-Atlantic units have been combined into a single stock complex for assessment purposes. A review of tagging studies for winter flounder (Howell 1996) indicates dispersion (and hence mixing) has occurred between previously defined Southern New England and Mid-Atlantic units. Howell (1996) noted that differences in growth and maturity among samples from Southern New England to the Mid-Atlantic may reflect discrete sampling along a gradient of changing growth and maturity rates over the range of a stock complex.
Differences in growth rates within the Mid-Atlantic units were observed to be greater than differences between Mid-Atlantic and Southern New England units (Howell, 1996). In offshore waters, the length structure of winter flounder caught in NEFSC research surveys is similar from Southern New England to New Jersey. Most commercial landings are obtained in these offshore regions (greater than 3 miles from shore).
Stock Boundaries and associated Statistical Areas The Gulf of Maine stock complex extends along the coast of eastern Maine to Provincetown, MA, corresponding to NEFSC commercial fishery statistical division 51 (Figure B2.1).
Recreational landings from Maine, New Hampshire and northern Massachusetts (northern half of Barnstable County and north to New Hampshire border) are associated with this stock complex.
The Southern New England/Mid-Atlantic stock complex extends from the coastal shelf east of Provincetown, MA southward along the Great South Channel (separating Nantucket Shoals and Georges Bank) to the southern geographic limits of winter flounder. NEFSC commercial fishery statistical areas within this boundary are 521 and 526, and statistical divisions 53, 61, 62, and 63.
The corresponding recreational areas are southern Massachusetts (the southern half of Barnstable County; Dukes, Nantucket and Bristol counties), Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland and Virginia. NEFSC survey strata included for this stock extend from the waters of outer Cape Cod to the south and west.
The Georges Bank stock extends eastward of the Great South Channel, including statistical areas 522, 525, and 551-562.
FISHERY DATA Landings Commercial landings from 1964-1981 was taken directly from the SARC 21 assessment (NEFSC 1996). Landings from 1981-1993 was estimated from the weighout data and landings from 1994-2001 comes from a proration of dealer and vessel trip report (VTR) data (Table B2.1).
224 36th SAW Consensus Summary
Commercial landings were near 1,000 mt from 1964 to the mid 1970s. Thereafter commercial landings increased to a peaked of 2,793 mt in 1982, and then steadily declined to a record low of 253 mt in 1999. Landings have remained near 500 mt since 1999 (Table B2.1, Figure B2.2).
Otter trawl was the primary gear use during 1964-1985; > 95% of the landings (Table B2.2, Figure B2.2). Since 1985 the proportion of landings coming from gillnets has increased, and has averaged 25% since 1990. Over 95% of the landings came from Massachusetts since 1997 (Table B2.3, Figure B2.3). The proportion of winter flounder commercial landings taken in Maine has decrease from an average of 25 percent of the landings in the early 1980s to less than 5% of the landings from 1995-2001. Over 90% of the commercial landings came from statistical area 514 since 1996 (Table B2.4, Figure B2.4). Commercial landings are taken relatively constant over the year (Table B2.5, Figure B2.5). There has been a decrease in the proportion of the landings in the large market category in the last few years (Table B2.6, Figure B2.6).
Recreational landings reached a peak in 1981 of 2,554 mt but declined substantially thereafter (Table B2.7, Figure B2.7). Landings have been less than 100 mt since 1995, with the lowest estimated landings in 1998 of 30 mt. Landings in 2001 for the Gulf of Maine winter flounder were 43 mt. The proportion of recreational landings from Maine has decreased similarly to the commercial landings (Tables B2.8-9). The proportion of recreational landings taken by halfyear has fluctuated from 1981 to 2001 (Tables B2.10-11).
Landed Age Compositions Commercial fishery Length samples of winter flounder are available from both the commercial and recreational landings. In the commercial fishery, annual sampling intensity varied from 4 to 310 mt landed per sample during 1982-2001. Overall sampling intensity was adequate, however temporal and market category coverage in some years was poor (Table B2.12). Samples were pooled to halfyear when possible. In 1982 mediums were pooled with unclassified by halfyear; in 1985 and 1995 smalls were pooled with mediums; the large sample from 1998 was also used to characterize 1999; and the 2001 large samples were used to characterize the 1999 large market category. Sampling coverage may have been poor but length frequency samples appeared relatively constant over time and there was a substantial amount of overlap between market categories which helped justify the pooling used in the assessment. Length data from the obsever data was used to supplement length data of unclassified fish. The large number of lengths sampled in the observer data for gillnet trips were used to characterize the gillnet proportion of the landings from 1990-2001 (Table B2.13). There has been a slight shift in the commercial catch at length to larger fish since 1982. The total amount of fish aged in the commercial landings varied from 130 to 1,182 ages (Table B2.14).
Recreational fishery Recreational landings at length were estimated seasonally (January-June and July-December) from 1982-2001 using the Marine Recreational Fisheries Statistics Survey (MRFSS).
Recreational length sampling intensity varied from poorly sampled years in the beginning of the time series (1982-1987 average of 375 mt per 100 lengths) to relatively good sampling from the late 1980s to early 1990s (1988-1997 average of 109 mt per 100 lengths), and more recently 36th SAW Consensus Summary 225
(1998-2001) the sampling intensity has decreased to an average of 179 mt per 100 lengths.
Combined Massachusetts Division of Marine Fisheries (MADMF) spring and NEFSC spring surveys and the NEFSC fall survey were used to age recreational length frequencies by halfyear from 1982-2001.
Discard estimates and age compositions Commercial fishery Discards were estimated for the large mesh otter trawl (1982-2001), gillnet (1986-2001), and northern shrimp fishery (1982-2001; Table B2.15). Discard data for the small mesh trawl fishery was judged inadequate for estimating discards (Tables B2.15-16). Discard rates in the small mesh trawl fishery were assumed to be the same as for large mesh trawls and to have the same size distribution.
The survey culling ogive method was used in estimating both the discard magnitude and discard proportion at length for the large mesh trawl fishery on a yearly basis from 1982-1993 (Mayo et al. 1992). VTR data was used to estimate the discard magnitude from 1994-2001, and the survey method used to estimate only the discard proportion at length for these years (Table B2.17).
Survey length frequency data (MADMF survey spring and fall) were smoothed using a three point moving average, then filtered through a mesh selection ogive (Simpson 1989) for 5 in mesh (1982), 5.5 in mesh (1983-1993), and a 6 in mesh (1994-2001). The 5.5 and 6 in mesh selection curve were calculated using the 5 inch curve adjusted to an L50 for 5.5 and 6 in mesh respectively. The choice of mesh sizes was based on sizes used in the American Plaice assessment for the Gulf of Maine (OBrien and Esteves 2001). The mesh filtering process resulted in a survey length frequency of retained winter flounder. A logistic regression was used to model the percent discarded at length (culling ogive) from 1989-2000 observer data (Figures B2.8-9), and the resulting percentages at length were applied to the survey numbers at length data to produce the survey-based equivalent of commercial kept and discarded winter flounder. The 1989-1993 average percentage discard at length was applied to 1982-1993. The 1995-2000 average percentage discard at length was applied to 1994-2001. The survey numbers per tow at length "kept" were then regressed against commercial numbers landed at length. The linear relationship was calculated for those lengths common to both length frequencies and fitted with an intercept of zero. The slope of the regression provided a conversion factor to re-scale the survey "discard" numbers per tow at length to equivalent commercial numbers at length. The resulting vector of number of fish discarded at length was multiplied by a discard mortality rate of 50% (as averaged in Howell et al., 1992) to produce the vector of fish discarded dead at length per year. The number of dead discards at length was summed across lengths (and corresponding weight at length) to produce the annual total number and weight of commercial fishery discards for 1982-1993. NEFSC combined spring and fall survey age-length keys were applied to convert discard length frequencies to age.
The ASMFC Winter Flounder Technical Committee has considered NEFSC Fishery Observer data (OB), and NER Vessel Trip Report (VTR) data as sources of information to use in the estimation of commercial fishery discards (Tables B2.15-18). The Committee examined the characteristics of both the Fishery Observer and VTR discard data (number of trips/tows 226 36th SAW Consensus Summary
sampled, frequency distributions of discards to landings ratio per trip, mean and variance of annual/half-year discards to landings ratios), and concluded that the VTR sum discard to landed ratio aggregated over all trips provided the most reliable data from which to estimate large mesh trawl discards. VTR large mesh trawl gear discards to landings ratios were applied to the total commercial trawl fishery landings to estimate discards in weight from 1994 to 2001. The Fishery Observer length frequency samples were judged inadequate to characterize the proportion discarded at length for the trawl fishery and the length proportion from the survey method (described above) was used to characterize the size distribution of discarded fish (Table B2.16).
Fishery Observer discarded to landing ratios (annual total discards for all trips to annual total landings for all trips) were used for estimating gillnet discard rates, and observer discarded to days fished ratios (shrimp season total discards for all trips to total shrimp fishery days fished for all trips) were used for estimating shrimp discards, since landings of winter flounder in the shrimp fishery is prohibited (Table B2.18). Estimated annual total days fished in the shrimp fishery was calculated as in Wigley et al. 1999. Discard estimates in the shrimp fishery were based on a shrimp fishery season (December-April). The shrimp season catch at age was then adjusted to the appropriate calendar year and age using the proportion of calendar year landings.
The average ratio for shrimp discards from 1989 to 1992 (before Nordmore grate requirement) was used for years (1982-1988) when observer data were not available. The 1989-1993 average gillnet ratios were used for 1986 to 1988.
The observer length frequency samples for gillnet and the northern shrimp fishery were used to characterize the proportion discarded at length. Total lengths from shrimp fishery observer discard data from 1989-1992 were used to characterize years 1982-1988 and total lengths from 1993-1997 were used for years 1998 to 2001. Total gillnet lengths from 1990-1993 were used to characterize years 1986 to 1989. Gillnet lengths in 1990 and 1992 were used to supplement lengths in 1991. The sample proportion at length, converted to weight, was used to convert the discard estimate in weight to numbers at length. As in the southern New England stock (NEFSC 1999), the resulting number of fish discarded at length was multiplied by a discard mortality rate of 50% (as averaged in Howell et al., 1992) to produce the number of fish discarded dead at length for all estimated commercial discard sources. Ages were determined using NEFSC/MADMF spring and NEFSC fall survey age-length keys.
Recreational fishery A discard mortality of 15% was assumed for recreational discards (B2 category from MRFSS data), as assumed in Howell et al. (1992). Discard losses peaked in 1982 at 140,000 fish.
Discards have since declined reaching a low in 1999 of 7,000 fish. In 2001, 15,000 fish were estimated to have been discarded (Table B2.7, Figure B2.7). Since 1997, irregular sampling of the recreational fisheries by state fisheries agencies has indicated that the discard is usually of fish below the minimum landing size of 12 inches (30 cm). For 1982-2001, the recreational discard has been assumed to have the same length frequency as the catch in the MADMF survey below the legal size and above an assumed hookable fish size (13 cm). When a size limit did not exist from 1982-1984 it was assumed that all fish discard were below 23 cm based on some length frequency information of discarded fish from the American Littoral Society tagging data.
The recreational discard for 1982-2001 is aged using NEFSC/MADMF spring and NEFSC fall 36th SAW Consensus Summary 227
survey age-length keys.
Mean Weights at Age in the Catch Mean weights at age were determined for the landings and discards in the commercial and recreational fisheries (Figure B2.10). Length frequencies (cm) for each component were converted to weight (kg) using length-weight equations derived from NEFSC survey samples:
Spring surveys: wt = 0.00000997
- length 3.055236 Fall surveys: wt = 0.00000925
- length 3.095188 The equations from the spring and fall surveys were applied to catches during the corresponding time periods. The annual mean weights at age from the commercial and recreational fisheries were used in the virtual population analysis and yield per recruit calculations.
Total Catch Estimates of the individual catch and mean weights at age components which made up the total catch are present in Tables B2.19 through B2.30 and Figure B2.11. The total catch during this period has varied from a high of 5,034 mt (14.2 million fish) in 1982 to a low of 300 mt (0.6 million fish) in 1999 (Tables B2.31-32). The total catch estimates include commercial and recreational landings and discards (Figure B2.12). Total catch and mean weights at age as aggregated for input to the VPA (ages 1-8+) are presented in Tables B2.33 and B2.34 (Figure B2.13). A summary of how the catch at age is was constructed can be seen in Table B2.35.
RESEARCH SURVEY ABUNDANCE AND BIOMASS INDICES Research surveys Mean weight and number per tow abundance indices were determined from spring (1979-2002) and fall (1979-2002) NEFSC and MADMF bottom trawl surveys (Table B2.36). Winter flounder are not found in the central Gulf of Maine and these strata (24, 28, 29, 37, and 36) were dropped from the index (Figures B2.14-15). Indices from the NEFSC spring and fall surveys were based on tows in offshore strata 26, 27, 38 to 40 and inshore strata 58 to 61, 65, and 66 (Figures B2.16-19). A longer spring (1968-2002) and fall (1963-2002) NEFSC survey index was also calculated which was limited to just offshore strata (26,27,38,39,40) since inshore strata were not sampled prior to 1979 in the Gulf of Maine (Figures B2.18-19). All MADMF strata sampled north of Cape Cod (25-36) were included in the index (Figures B2.20-21).
Survey trends by individual strata in the NEFSC survey suggests a decreasing trend in the northern part of the stock off the coast of Maine and an increasing trend in the southern stock component off Massachusetts which mirrors the trend seen in the landings by state and statistical area (Figures B2.16-17). Higher catches of winter flounder are seen in the MADMF survey with individual strata following similar trends. All of the indices generally dropped from the beginning of the time series in the early 1980s to a low point in the early to mid- 1990s, then increase slightly in the late 1990s (Table B2.36). All of the indices generally show increases 228 36th SAW Consensus Summary
during 1998 and 1999. Similar trends were seen between the inshore/offshore index and the index limited to just the offshore strata regardless of the increased variability in the offshore series due to less fish inhabiting the deeper waters of the offshore strata (Figures B2.18-19).
The Seabrook Nuclear Power Plant in New Hampshire has conducted a monthly bottom trawl survey at 3 fixed stations in Southern New Hampshire since 1975. Four replicate tows using a shrimp trawl were made at each station once per month from 1975-1983. Sampling changed to two replicate tows twice per month in 1985. Length data was collected from 1985-2001 with the exception of 1993. The monthly survey was broken down to a spring and fall survey. The Fall survey index was not used for tunning due to a lack of sampling in more recent years at one of the three stations because of the presence of lobster gear. In addition, appropriate age data in the fall does not exist for aging the smaller fish caught in this survey. MADMF spring survey ages were used to age the Seabrook spring index. This survey also shows an increase in the number of fish in the late 1990s (Figure B2.22).
MADMF catches a larger proportion of smaller fish than the NEFSC surveys. Survey numbers at age is summarized in Tables B2.37 through B2.41. No MADMF age data are currently available for the fall survey or for 2002 in the Spring. The NEFSC age data was used to age missing ages in the MADMF survey.
ESTIMATES OF MORTALITY AND STOCK SIZE Natural Mortality Instantaneous natural mortality (M) for winter flounder was assumed to be 0.20 and constant across ages as in the SNE winter flounder stock. Commercial catch at age included fish to age 13, under conditions of relatively high fishing mortality. If M = 0.25, less than 5% of the population would reach age 12 under conditions of no fishing mortality. Therefore, the SARC felt that M = 0.2, which represents a maximum age of 15, was representative of the stock.
Maturity The VPA assessment uses the maturity schedule as published in OBrien et al. (1993) for winter flounder north of Cape Cod, based on data from the MADMF spring trawl survey for strata 25-36 (state waters east and north of Boston and Cape Cod Bay) sampled during 1985-1989 (n = 215 males, n = 320 females). Those data provided estimates of lengths and ages of 50% maturity of 27.6 cm and 3.3 yr for males, and 29.7 cm and 3.5 yr for females, and estimated proportions mature at age as follows:
Age 1 2 3 4 5 6 7+
Males 0.00 0.04 0.34 0.87 0.99 1.00 1.00 Females 0.00 0.01 0.16 0.86 0.99 1.00 1.00 36th SAW Consensus Summary 229
The female schedule (with the proportion at age 2 rounded down to 0.00 and the proportion at age 5 rounded up to 1.00) was used in the present VPA and YPR assessment.
The SARC has examined NEFSC spring trawl survey data over the 1981-2001 period in an attempt to better characterize the maturity characteristics of the Gulf of Maine winter flounder.
Data were analyzed in 5-6 year blocks (1981-1985, 1986-1990, 1991-1995, and 1996-2001) and for the entire time period (1981-2001), for each sex and combined sexes (Tables B2.42-43).
Observed proportions mature at age were tabulated, and from those data maturity ogives at length and age were calculated to provide estimated proportions mature at age.
In general, the NEFSC maturity data for the sexes combined indicated earlier maturity than the MADMF data, with L50% values ranging from 21-24 cm, rather than from 28-29 cm, and with 50% maturity for age 2.5 fish, rather than 50% maturity for age 3.3 fish (Table B2.42). To investigate the apparent inconsistency between the MADMF and NEFSC maturity data, the SARC compared the two data sets over the same time periods (1981-1985, 1986-1990, 1991-1995, 1996-2001, and 1981-2001) and area of survey coverage (MADMF strata 25-36; NEFSC inshore strata 58-66). For comparable time periods and geographic areas, the NEFSC maturity data still consistently indicated a smaller size and younger age of 50% maturity than the MADMF data. NEFSC L50% and A50% values range from 21-25 cm and about 2.5 yr, while the MADMF values range from 28-29 cm and about 3.3 yr (Table B2.44, Figure B2.23). The difference is still nearly a full age class difference at 50% maturity. These results are very similar to the differences seen between the MADMF and NEFSC surveys for the southern New England winter flounder stock.
Given that both length and age vary in the same direction, it seems unlikely that the differences could be attributed to aging differences between the two data sets. The comparison of MADMF and NEFSC maturity estimates over the same time period and location suggests the observed difference is not due to immature and mature fish in the 20 - 30 cm size-class being segregated by area e.g., mature fish in that size interval tending to occupy inshore areas during the spring with immature fish tending to remain offshore. The difference between MADMF and NEFSC surveys is consistent over time. The differences may be due to differences in interpretation of maturity stage for fish sizes between 20-30 cm between MADMF and NEFSC survey staff.
The SARC considered these data and analyses and the possible causes for the noted inconsistencies, and concluded that more detailed spatial and temporal analyses and/or a maturity workshop on the interpretation of maturity stages is needed before revisions to the maturity schedule can be adopted. Therefore, the maturity at age schedule published by OBrien et al.
1993 was used for this assessment.
Virtual Population Analysis Tuning The Virtual Population Analysis (VPA) was tuned (calibrated) using the NEFSC Woods Hole Fisheries Assessment Compilation Toolbox (FACT) version 1.50 of the ADAPT VPA (Conser 230 36th SAW Consensus Summary
and Powers 1990). Abundance indices at age were available from several research surveys:
NEFSC spring bottom trawl ages 1-8+, NEFSC fall ages 1-8+ (advanced to tune January 1 abundance of ages 2-8+), 1-5, Massachusetts spring ages 1-8+, Massachusetts fall ages 0-8+
(advanced to tune January 1 abundance of ages 1-8+), and Seabrook spring trawl survey ages 1-8+. Survey indices were selected for inclusion in VPA tuning based on consideration of the partial variance in a VPA trial run including all indices, residual error patterns from the various trail runs, and on the significance of the correlation among indices and with VPA abundance estimates from the trail run including all indices. A conditional non-parametric bootstrap procedure (Efron 1982) was used to evaluate the precision of fishing mortality and spawning stock biomass. A retrospective analysis was performed for terminal year fishing mortality, spawning stock biomass, and age 1 recruitment.
VPA diagnostics The SARC considered 6 different configurations of tuning indices with the catch at age estimated to 8+ from 1982 to 2001. Run GOMWFS36_ALL was the initial trial including all indices. The results of the VPA were not sensitivity to the method used in estimating large mesh discards i.e.
using the survey method only or using the survey method and vtr data to estimate discards (run GOMWFS36_survey). In addition, VPA result were not sensitivity to excluding all discards from the catch at age (GOMWFS36_no_dis). In general, tuning indices were excluded if they exhibited high partial variance (indicating a lack of fit within the VPA model) and low correlation with other indices with similar spatial and temporal characteristics and with the VPA estimates of stock size.
Run GOMWFS36_2 excluded six indices with high partial variance within the VPA and low correlation with other indices and/or the VPA estimates of stock size, resulting in improvements both in overall fit (Mean Square Residual (MSR) reduced by 25%) and in the precision of the stock size estimates. Run GOMWFS36_3 dropped an additional five indices from the GOMWFS36_2 configuration, resulting in some improvements in fit but this run also resulted in a decrease in the precision around age-1 stock numbers at age. Run GOMWFS36_no_age1 has the same survey indices as GOMWFS36_3, but did not estimate stock size at age 1, and provided virtually the same results. Therefore, GOMWFS36 _2 was the run adopted as final by the SARC, and is the basis for all further analyses (Table B2.45).
Fishing Mortality, Spawning Stock Biomass, and Recruitment During 1982-1995, fishing mortality (fully recruited F, ages 5-6) has varied between 0.5 (1983) and 1.9 (1995). Fishing mortality has declined to a range of 0.06-0.14 during 1999-2001 (Figure B2.24). Accounting for the uncertainty of the 2001 estimate, there is an 80% probability that F in 2001 was between 0.12 and 0.16 (Table B2.46, Figure B2.25). Spawning stock biomass (SSB) declined from 4,790 mt in 1982 to a record low of 666 mt in 1995. SSB has increased since 1995 to 5,866 mt in 2001 (Figure B2.26). Accounting for the uncertainty of the 2001 estimate, there is an 80% probability that SSB in 2001 was between 5,203 mt and 6,581 mt (Figure B2.25).
Recruitment declined continuously from 11.8 million age-1 fish in 1982 to 3.2 million in 1993.
Recruitment then averaged 7.8 million fish during 1995-2002 (Figure B2.26).
36th SAW Consensus Summary 231
Retrospective analysis A retrospective analysis of the VPA was conducted back to a terminal catch year of 1995 (Table B2.45b, Figure B2.27). The Gulf of Maine winter flounder VPA does exhibit a retrospective pattern in F from 1993 to 1998. Retrospective fishing mortality rates underestimate the current values by an average of 56% from 1993-1998. The most likely cause of this pattern is a combination of factors including under-reporting of the landings, mis-classification of the landings by stock area, and underestimation of the discards. There is a tendency for an overestimation of SSB during the late 1990s. For 1993-1998, retrospective SSB levels overestimate current values by an average of 92%.
Precision of Stock Size, F, and SSB estimates The precision of the 2002 stock size, fishing mortality at age in 2001, and SSB estimates from VPA was evaluated using bootstrap techniques (Efron 1982). Five hundred bootstrap iterations were realized in which errors (differences between predicted and observed survey values) were resampled. Bootstrap estimates of stock size at age indicate a bias of less than 5% for age 1-2 and a bias less than 4% for ages 3-8+. Bootstrap standard errors provide stock size CVs ranging from 16% at age 7 to 48% at age 1 (Table B2.46).
Bootstrapped estimates of spawning stock biomass indicate a CV of 9%, with low bias (bootstrap mean estimate of spawning stock biomass of 5,945 mt compared with VPA estimate of 5,866 mt). There is an 80% probability that spawning stock in 2001 was between 5,203 mt and 6,581 mt (Figure B2.25).
The bootstrap estimates of standard error associated with fishing mortality rates at age indicate good precision. Coefficients of variation for F estimates ranged from 16% at age 7 to 37% at ages 1. There is an 80% probability that fully recruited F for ages 5-6 in 2001 was between 0.12 and 0.16 (Figure B2.25).
BIOLOGICAL REFERENCE POINTS The ASMFC Winter Flounder Technical Committee followed the parametric modeling approach done for SNE winter flounder by the NEFSC Working Group on the Re-Evaluation of Biological Reference Points for New England Groundfish (RPWG; NEFSC 2002) in estimating biological reference points for Gulf of Maine winter flounder. The RPWG (NEFSC 2002) estimated biological reference points using yield and SSB per recruit (Thompson and Bell 1934) and Beverton-Holt/Ricker stock-recruitment models (Beverton and Holt 1957, Brodziak et al. 2001, Mace and Doonan 1988).
Yield and Spawning Stock Biomass per Recruit The yield and SSB per recruit analyses was estimated by the Technical Committee for Gulf of Maine winter flounder. Natural mortality was assumed to be 0.2. The proportion mature was taken from OBrien et. al (1993). The average partial recruitment pattern form 1999-2001 was used for ages 1 to 4. Full recruitment was assumed for 5 and older. The average catch weight 232 36th SAW Consensus Summary
from 1999-2001 was used for ages 1 to 7 and the Rivard weights were used for the stock weights for ages 1 to 7. An estimated von bertalanffy model for female Gulf of Maine winter flounder using MADMF data from Witherell and Burnett (1993) was used to estimate catch and stock weights for ages 8 to 15. The von Bertalanffy model for females was used since survey data indicates a skewed sex ratio for older ages. The yield and SSB per recruit analyses indicate that F40% and F0.1 = 0.26 (Table B2.47, Figure B2.28). Fmax was estimated to be 0.69.
Empirical Nonparametric approach If F40% is assumed to be an adequate proxy for Fmsy, then the fishing mortality threshold is 0.26.
This fishing mortality rate produces 0.8333 kg of spawning stock biomass per recruit and 0.1977 kg of yield per recruit (including discards). Since the VPA estimates of recruitment does not increase greatly with increasing spawning stock size, the mean of the time-series of recruitments (1982-2001) is assumed to be representative of recruitment levels expected at maximum sustainable yield (MSY). Thus, recruitment of 6.705 million fish results in an estimate of 5,587 mt of spawning stock biomass (SSBmsy proxy) and 1,326 mt of MSY.
Parametric Model Approach Maximum likelihood fits of the 10 parametric stock-recruitment models to the Gulf of Maine winter flounder VPA estimates for 1982-2001 are listed below (Table B2.48). The model acronyms are: BH = Beverton-Holt, ABH = Beverton-Holt with autoregressive errors, PBH =
Beverton-Holt with steepness prior, PABH = Beverton-Holt with steepness prior and autoregressive errors, PRBH = Beverton-Holt with recruitment prior, PRABH = Beverton-Holt with recruitment prior and autoregressive errors, RK = Ricker, ARK = Ricker with autoregressive errors, PRK = Ricker with slope at the origin prior, PARK = Ricker with slope at the origin prior and autoregressive errors. The six hierarchical criteria are applied to each of the models to determine the set of candidate models (NEFSC 2002).
- 1. Parameter estimates must not lie on the boundary of their feasible range of values.
- 2. The estimate of MSY lies within the range of observed landings.
- 3. The estimate of Smsy is not substantially greater than the nonparametric proxy estimate.
- 4. The estimate of Fmsy is not substantially greater than the value of Fmax.
- 5. The dominant frequencies for the autoregressive parameter, if applicable, lie within the range of one-half of the length of the stock-recruitment time series.
- 6. The estimate of recruitment at Smax, the maximum spawning stock size proxy input to the stock-recruitment model, is consistent with the value of recruitment used to compute the nonparametric proxy estimate of Smsy.
The fifth criterion is not satisfied by the ABH, PABH, PRABH, ARK, and PARK models. The RK, and ARK models do not satisfy criterion 4. The stock-recruitment data does not support overcompensatory effects at SSB predicted by the PRK model (Ricker model with slope at the origin prior). The three remaining models are BH, PBH, and PRBH. All three models estimated 36th SAW Consensus Summary 233
a high steepness parameter. The AIC assigns the greastest probability to the BH model (Figure B2.29). However similar point estimates of MSY, Fmsy, and Smsy are estimated by all three models. The standardized residual plot of the fit of the BH model to the stock-recruitment data shows that the standardized residuals generally lie within + two standard deviations of zero.
The SARC selected the parametric Berverton-Holt (BH) model for estimating biological reference points for Gulf of Maine winter flounder; MSY = 1,543 mt, Fmsy = 0.43, SSBmsy =
4,104 mt. The SARC concluded that the high steepness estimates from the Beverton-Holt models were within the feasible biological range and therefore estimating Fmsy using the (BH) parametric approach was preferred over assuming Fmsy = F40% in the empirical nonparametric approach. The high steepness estimate also likely resulted in similar estimates of SSBmsy between the empirical and parametric approach.
PROJECTIONS FOR 2002-20012 Stochastic projections were made based on 500 bootstrapped VPA realizations of stock size in numbers at age in 2002. The stochastic forecasts only incorporate uncertainty in 2002 stock sizes due to survey variability and assume current discard to landings proportions. Partial recruitment to the fishery and percentage discarded were estimated as the mean of VPA estimates for 1999-2001. For consistency with the partial recruitment averages, mean weights at age in the stock, landings, and discards were similarly estimated as the weighted (by number landed) geometric mean weight at age from 1999-2001.
Parametric approach Assuming F in 2002 will be equal to F in 2001 (F2002 = 0.14), landings are expected to be about 961 mt in 2002. At this status quo F, spawning stock biomass is projected to continue to increase to 7,623 mt in 2002. If fishing mortality rate is increased to Fmsy = 0.43 in 2003 spawning stock will decrease to 4,258 mt by 2013 with 50% probability which is slightly above the Bmsy = 4,104 mt estimate (Table B2.49).
If F in 2002 is assumed to be 15% less than F in 2001 (F2002 = 0.12), due to the impact of management measures implemented in response to court orders during 2002, then landings are expected to be about 831 mt in 2002. At this reduced F, spawning stock biomass is projected to continue to increase to 7,655 mt in 2002. If fishing mortality rate is increased to Fmsy = 0.43 in 2003 spawning stock will decrease to 4,260 mt by 2013 with 50% probability which is slightly above the Bmsy = 4,104 mt estimate (Table B2.49, Figure B2.30).
CONCLUSIONS The Gulf of Maine winter flounder stock is not overfished and overfishing is not occurring (Figure B2.31). Fully recruited fishing mortality in 2001 was 0.14 (exploitation rate = 12%),
about 67% below Fmsy = 0.43. There is an 80% chance that the 2001 F was between 0.12 and 234 36th SAW Consensus Summary
0.16. Spawning stock biomass was estimated to be 5,900 mt in 2001, about 44% above Bmsy =
4,100 mt. There is an 80% chance that the spawning stock biomass was between 5,200 mt and 6,600 mt in 2001.
Spawning stock biomass declined substantially from 4,800 mt in 1982 to700 mt in 1995, but has increased to about 5,900 mt in 2001 due to reduced fishing mortality rates since 1996.
Recruitment to the stock has been near or above average since 1995.
For 1993-1998 retrospective fishing mortality rates underestimate the current values by an average of 56%. The most likely cause of this pattern is a combination of factors including under-reporting of the landings, mis-classification of the landings by stock area, and underestimation of the discards. For 1993-1998, retrospective SSB levels overestimate current values by an average of 92%. While the GOM winter flounder VPA provides uncertain estimates of current F and SSB, it provides a better determination of stock status than reliance on survey indices alone. However, recent spatial distribution of both commercial landings and survey catches indicates that most of the recent stock rebuilding has taken place off the Massachusetts coast, with little evidence of rebuilding off the Maine coast.
Biological reference points for Gulf of Maine winter flounder were estimated using empirical, non-parametric and parametric stock-recruit modeling approaches. The yield and SSB per recruit analyses indicate that F40% = F0.1 = 0.26 and Fmax = 0.69. A parametric Beverton-Holt stock-recruitment model estimated values of Fmsy = 0.43, Bmsy = 4,100, and MSY = 1,500 mt. The SARC recommends that the parametric model reference points be adopted as the basis for the ASMFC and NEFMC FMP overfishing definitions.
SARC COMMENTS The SARC noted that a single survey length-weight relationship has been used for SNE-MA, GOM and GB winter flounder stocks, and suggested stock-specific parameters be explored in the next assessment.
The VPA indicates substantial rebuilding of the stock since 1995. The stock status of GOM winter flounder is somewhat unique among GOM groundfish stocks, as it is currently at a relatively high stock biomass and apparently subject to relatively low fishing mortality. The recent spatial distribution of commercial landings and survey catches indicates that most of the recent stock rebuilding has taken place off the Massachusetts coast, with little evidence of rebuilding off the Maine coast. This situation may be attributed to the restrictive regulations imposed in recent years in the areas where much of the current biomass is concentrated (e.g. area closures and gear and vessel restrictions in statistical areas 513 and 514).
The GOM winter flounder VPA, like the SNE-MA analysis, exhibits a retrospective pattern of underestimating fishing mortality (averaging 56%) and overestimating SSB (averaging 92%)
during the period 1993-1998. The observed retrospective pattern is likely caused by under-reporting or under-estimating the catch. The SARC concluded that, while the GOM winter flounder VPA provides uncertain estimates of current F and SSB, it provides a better 36th SAW Consensus Summary 235
determination of stock status than would reliance on survey indices alone.
As this is a new, benchmark analytical assessment for GOM winter flounder, biological reference points based on the analytical results have been estimated for the first time. The SARC discussed options for the analyses to be used as the basis for defining overfishing. It was noted that the ASMFC Winter Flounder Technical Committee preferred the empirical non-parametric approach, based on concerns over the relatively high stock resilience (i.e. relatively high estimates of the model steepness parameter, and therefore the estimated FMSY) of the stock inferred from the stock-recruitment models. The SARC agreed with the Technical Committee's conclusion to reject the Ricker stock-recruitment model estimates of reference points, based on:
- 1) the lack of evidence of population dynamics (e.g. cannibalism, high degree of spatial interference among adults and recruits) that would justify a high degree of density-dependent compensation in recruitment; and 2) the lack of VPA or hindcast stock-recruitment estimates at biomass levels where there might be such compensation. The SARC concluded that the Beverton-Holt stock-recruitment model provided reasonable reference points for the stock, and recommended that they be adopted as the basis for the ASMFC and NEFSC FMP overfishing definitions.
SOURCES OF UNCERTAINTY
- 1) Stock-specific landings data for 1994 and later are derived by proration from Vessel Trip Report data and are considered provisional.
- 2) The lack of a long time series of survey coverage in inshore New Hampshire and Maine waters, where winter flounder are abundant, is a source of uncertainty. The small number of survey tows in inshore Massachusetts strata in the NEFSC survey results in uncertainty in the index.
- 3) Length frequency sampling intensity of the commercial and recreational fishery landings has been low in some recent years, and likely increases the uncertainty of the estimated landings at age.
- 4) Observer sampling intensity of the commercial trawl fishery has been low. Shrimp fishery discard sampling has been discontinued in recent years. Commercial fishery discard estimates are based on rates provided by fishers in the Vessel Trip Reports, owing to inadequate Fishery Observer sampling.
- 5) Scales and otoliths collected by the MADMF fall survey are not aged. In addition, the MADMF 2002 spring survey scales and otoliths were not aged, which likely resulted in an underestimation of the high incoming recruitment evident from the length frequency distributions in the Fall 2000 and Spring 2002 surveys.
- 6) Differences in the age at maturity between the MADMF and NEFSC spring surveys are a source of uncertainty.
236 36th SAW Consensus Summary
- 7) The Gulf of Maine winter flounder VPA exhibits a retrospective pattern of underestimating F from 1993 to 1998 and overestimating SSB during the late 1990s.
RESEARCH RECOMMENDATIONS New
- 1) The MADMF fall survey does collect winter flounder otoliths and scales, so ageing such material should be undertaken.
- 2) Increase the number of tows and/or consistently sample inshore strata in the NEFSC bottom trawl survey.
- 3) Increase MRFSS length sampling intensity in the recreational fishery.
- 4) Increase temporal and market category coverage of length sampling in the commercial landings.
- 5) Increase the intensity of observer sampling especially with small- and large-mesh trawl gear.
- 6) Examine the sources of discrepancy between NEFSC and MA survey maturity estimates.
- 7) Initiate periodic maturity staging workshops, involving State and NEFSC trawl survey staff.
- 8) Incorporate the results from the MEDMR research trawl survey (begun in 2001) into the assessment as they become available.
- 9) Investigate derivation of stock-specific parameters for the next assessment.
- 10) Attempt use of a forward projection (statistical catch at age model) in the next assessment.
Old
- 1) Examine the implications of anthropogenic mortalities caused by pollution and power plant entrainment in estimating yield per recruit, if feasible.
- 2) Examine growth variations within the Gulf of Maine, using results from the Gulf of Maine Biological Sampling Survey (1993-1994).
- 3) Further examine the stock boundaries to determine if Bay of Fundy winter flounder should be included in the Gulf of Maine stock complex.
36th SAW Consensus Summary 237
Old: completed
- 1) Process archived age samples from NEFSC surveys and commercial landings, and develop an analytical age based assessment.
- 2) Estimate biological reference points for Gulf of Maine winter flounder.
238 36th SAW Consensus Summary
LITERATURE CITED ASMFC. 1998. Assessment of the Southern New England/Mid-Atlantic and Gulf of Maine Winter Flounder stocks: a report by the ASMFC Winter Flounder Technical Committee.
ASMFC WFTC Document 98-01. 31 p + app.
Bigelow, H. and W. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin of the Fish and Wildlife Service. V. 53. Fishery Bulletin 74.
Brodziak, J.T.K., W.J. Overholtz, and P. Rago. 2001. Does spawning stock affect recruitment of New England groundfish? Can. J. Fish. Aquat. Sci. 58(2): 306-318.
Beverton, R.J.H., and S.J. Holt. 1957. On the dynamics of exploited fish populations.
Chapman and Hall, London. Facsimile reprint 1993.
Conser, R. and J. Powers. 1990. Extension of the ADAPT VPA tuning method designed to facilitate assessment work on tuna and swordfish stocks. Int. Comm. Conserv. Atlantic Tunas. Coll. Vol. Sci. Pap. 32: 461-467.
Efron, B. 1982. The jackknife, the bootstrap and other resampling plans. Phila. Soc. for Ind. and Appl. Math. 38.
Howell, P. 1996. Identification of stock units. NEFSC Res. Doc.96-05b.
Howell, P., A. Howe, M. Gibson and S. Ayvasian. 1992. Fishery management plan for inshore stocks of winter flounder. Atlantic States Marine Fisheries Commission. Fisheries Management Report No. 21. May, 1992.
Mace, P.M., and I.J. Doonan. 1988. A generalized bioeconomic simulation model for fish population dynamics. N.Z. Fish. Ass. Res. Doc. 88/4.
Mayo, R.K., L. OBrien, and N. Buxton. 1992. Discard estimates of American plaice, Hippoglossoides platessoides, in the Gulf of Maine northern shrimp fishery and the Gulf of Maine-Georges Bank large-mesh otter trawl fishery. SAW 14 Res. Doc. 14/3. 40 pp.
NEFSC. 1996. Report of the 21th Northeast Regional Stock Assessment Workshop (21th SAW):
Stock Assessment Review Committee (SARC) consensus summary of assessments.
Northeast Fish. Sci. Cent. Ref. Doc.
NEFSC. 1999. Report of the 28th Northeast Regional Stock Assessment Workshop (28th SAW):
Stock Assessment Review Committee (SARC) consensus summary of assessments.
Northeast Fish. Sci. Cent. Ref. Doc. 99-08. 304 p.
NEFSC. 2002. Final report of the Working Group on re-evaluation of biological reference points for New England groundfish. Northeast Fish. Sci. Cent. Ref. Doc. 02-04. 123 p.
36th SAW Consensus Summary 239
O'Brien, L., J. Burnett, and R. Mayo. 1993. Maturation of nineteen species of finfish off the northeast coast of the United States, 1985-1990. NOAA Tech. Rep. NMFS 113. 66 pp.
O'Brien, L. and C. Esteves. 2001. Update Assessment of American Plaice in the Gulf of Maine -
Georges Bank Region for 2000. SAW No. 32. CRD-01-02 198 p.
Simpson, D.G. 1989. Codend selection of winter flounder Pseudopleuronectes americanus.
NOAA Tech. Rpt. NMFS 75. 10 p.
Thompson, W. F. and F. H. Bell. 1934. Biological statistics of the Pacific halibut fishery. 2.
Effect of changes in intensity upon total yield and yield per recruit of gear. Rep. Int. Fish.
(Pacific halibut) Comm. 8: 49 p.
Wigley S.E., J.K.T. Brodziak, and S.X. Cadrin. 1999. Assessment of the witch flounder stock in subareas 5 and 6 for 1999. Northeast Fish. Sci. Cent. Ref. Doc. 99-16. 40 p.
240 36th SAW Consensus Summary
Table B2.1. Winter flounder commercial landings (metric tons) for the Gulf of Maine stock (U.S. statistical reporting areas 512 to 515). Landings from 1964-1981 is taken directly from SARC 21, 1982-1993 is re-estimated from the wodets, data and 1994-2001 is estimated using prorated dealer and VTR data.
Year metric tons 1964 1,081 1965 665 1966 785 1967 803 1968 864 1969 975 1970 1,092 1971 1,113 1972 1,085 1973 1,080 1974 885 1975 1,181 1976 1,465 1977 2,161 1978 2,194 1979 2,021 1980 2,437 1981 2,406 1982 2,793 1983 2,096 1984 1,699 1985 1,582 1986 1,188 1987 1,140 1988 1,250 1989 1,253 1990 1,116 1991 1,008 1992 825 1993 611 1994 552 1995 796 1996 600 1997 618 1998 637 1999 253 2000 382 2001 571 36th SAW Consensus Summary 241
Table B2.2. Percent commercial landings by gear for Gulf of Maine winter flounder.
Year otter trawl shrimp trawl gillnet other 1964 96% 1% 3%
1965 95% - 2% 3%
1966 98% - 1% 2%
1967 99% - - 1%
1968 98% - - 2%
1969 99% - - 1%
1970 99% - 1% -
1971 95% - 4% 1%
1972 95% - 4% 1%
1973 97% - 2% -
1974 95% - 5% -
1975 92% 4% 1% 3%
1976 87% 2% 6% 5%
1977 93% 1% 3% 3%
1978 89% - 3% 9%
1979 94% - 1% 5%
1980 95% - 1% 4%
1981 92% 3% 1% 3%
1982 89% 5% 2% 4%
1983 87% 7% 3% 4%
1984 85% 8% 2% 6%
1985 91% 4% 1% 4%
1986 77% 6% 14% 4%
1987 74% 8% 12% 5%
1988 81% 5% 13% 1%
1989 80% 5% 11% 4%
1990 77% 2% 19% 2%
1991 86% 2% 9% 2%
1992 77% 2% 19% 2%
1993 75% - 23% 2%
1994 78% - 21% 1%
1995 66% - 32% 3%
1996 72% - 27% 1%
1997 72% - 27% 1%
1998 73% - 27% 1%
1999 65% - 33% 1%
2000 73% - 26% 1%
2001 77% - 22% 1%
242 36th SAW Consensus Summary
Table B2.3. Percent commercial landings by state for Gulf of Maine winter flounder.
Year ME NH MA RI 1964 3% - 97% -
1965 7% - 93% -
1966 6% - 94% -
1967 6% - 94% -
1968 3% - 97% -
1969 4% - 96% -
1970 13% - 87% -
1971 6% - 93% 1%
1972 12% - 88% -
1973 9% - 91% -
1974 13% - 87% -
1975 20% - 80% -
1976 12% - 88% -
1977 9% - 91% -
1978 14% - 86% -
1979 21% - 79% -
1980 23% - 77% -
1981 27% 2% 71% -
1982 32% 4% 64% -
1983 31% 4% 65% -
1984 23% 6% 71% -
1985 21% 5% 74% 1%
1986 22% 4% 73% -
1987 19% 8% 72% 1%
1988 22% 9% 69% -
1989 18% 9% 72% -
1990 14% 7% 78% -
1991 16% 7% 76% -
1992 14% 7% 79% -
1993 8% 6% 86% -
1994 5% 7% 88% -
1995 3% 4% 93% -
1996 1% 5% 94% -
1997 3% 2% 95% -
1998 1% 2% 97% -
1999 - 3% 97% -
2000 - 4% 95% 1%
2001 1% 3% 96% -
36th SAW Consensus Summary 243
Table B2.4. Percent commercial landings by statistical area for Gulf of Maine winter flounder.
Year 511 512 513 514 515 1964 - 2% 1% 96% -
1965 - 1% 6% 92% 1%
1966 - 2% 7% 90% -
1967 - 1% 6% 94% -
1968 - 2% 1% 97% -
1969 - 1% 4% 95% -
1970 - 1% 12% 87% -
1971 - 1% 6% 93% -
1972 - 1% 12% 87% -
1973 - 1% 8% 91% -
1974 - 2% 11% 87% -
1975 1% 2% 18% 79% -
1976 - 1% 13% 86% -
1977 - 2% 9% 89% -
1978 - 3% 13% 83% -
1979 2% 4% 18% 77% -
1980 1% 3% 20% 76% 1%
1981 - 3% 27% 69% 1%
1982 3% 5% 27% 62% 2%
1983 2% 4% 29% 64% 1%
1984 1% 3% 27% 68% 1%
1985 4% 2% 21% 70% 2%
1986 4% 5% 26% 64% 2%
1987 2% 3% 25% 69% 1%
1988 4% 6% 22% 67% 1%
1989 1% 5% 24% 69% 2%
1990 4% 3% 21% 71% 1%
1991 2% 1% 23% 68% 5%
1992 1% 3% 21% 73% 3%
1993 1% - 17% 81% 2%
1994 - 2% 14% 81% 2%
1995 2% 9% 8% 80% 1%
1996 - - 9% 90% 1%
1997 - - 9% 90% 1%
1998 - - 4% 96% -
1999 - - 3% 94% 2%
2000 1% - 5% 94% -
2001 - - 4% 95% -
244 36th SAW Consensus Summary
Table B2.5. Percent commercial landings by quarter for Gulf of Maine winter flounder.
year 1 2 3 4 1964 21% 31% 22% 27%
1965 22% 27% 11% 40%
1966 21% 23% 8% 48%
1967 15% 35% 8% 42%
1968 12% 39% 17% 32%
1969 23% 37% 15% 26%
1970 19% 40% 11% 30%
1971 25% 33% 19% 22%
1972 23% 34% 18% 25%
1973 24% 27% 16% 33%
1974 22% 30% 7% 41%
1975 18% 25% 17% 40%
1976 22% 18% 18% 42%
1977 24% 19% 13% 44%
1978 21% 32% 12% 35%
1979 13% 28% 17% 42%
1980 17% 30% 16% 37%
1981 23% 28% 14% 34%
1982 24% 28% 9% 38%
1983 28% 31% 12% 30%
1984 29% 27% 8% 36%
1985 26% 31% 10% 33%
1986 33% 32% 7% 29%
1987 29% 34% 7% 30%
1988 30% 29% 7% 34%
1989 27% 39% 8% 27%
1990 27% 38% 10% 26%
1991 26% 32% 9% 32%
1992 26% 36% 7% 32%
1993 18% 37% 11% 34%
1994 13% 38% 11% 38%
1995 22% 38% 15% 25%
1996 20% 38% 10% 32%
1997 18% 34% 16% 31%
1998 16% 44% 13% 28%
1999 13% 44% 17% 25%
2000 15% 39% 17% 29%
2001 9% 41% 17% 32%
36th SAW Consensus Summary 245
Table B2.6. Percent commercial landings by market category for Gulf of Maine winter flounder.
year unclassified small medium large 1964 77% - - 23%
1965 66% - - 34%
1966 68% - - 32%
1967 78% - - 22%
1968 70% - - 30%
1969 71% - - 29%
1970 75% - - 25%
1971 71% - - 29%
1972 64% - - 36%
1973 - 40% - 60%
1974 - 38% - 62%
1975 - 31% - 69%
1976 - 42% - 58%
1977 - 53% - 47%
1978 - 50% - 50%
1979 - 51% - 49%
1980 - 49% - 50%
1981 3% 47% - 50%
1982 12% 41% 2% 44%
1983 15% 48% 3% 35%
1984 15% 46% 7% 33%
1985 11% 41% 17% 31%
1986 17% 39% 16% 29%
1987 22% 36% 20% 23%
1988 19% 42% 17% 22%
1989 20% 35% 20% 25%
1990 22% 34% 15% 29%
1991 15% 34% 22% 29%
1992 16% 33% 23% 29%
1993 14% 32% 29% 25%
1994 14% 33% 28% 26%
1995 12% 46% 18% 25%
1996 10% 56% 17% 18%
1997 10% 46% 25% 20%
1998 29% 44% 18% 9%
1999 42% 32% 18% 7%
2000 36% 41% 14% 9%
2001 36% 30% 28% 6%
246 36th SAW Consensus Summary
Table B2.7. Estimated number (000's) and weight (mt) of winter flounder caught, landed, and discarded in the recreational fishery, Gulf of Maine stock.
Numbers (000s) Metric Tons Year Catch Landed Released 15 % Release Landed A+B1+B2 A+B1 B2 Mortality A+B2 1981 6,200 5,433 767 115 2,554 1982 8,207 7,274 933 140 1,876 1983 2,169 1,988 181 27 868 1984 2,477 2,285 191 29 1,300 1985 3,694 3,220 474 71 1,896 1986 946 691 255 38 523 1987 3,070 2,391 679 102 1,809 1988 953 841 111 17 345 1989 1,971 1,678 294 44 620 1990 786 652 134 20 370 1991 213 154 59 9 91 1992 186 137 48 7 90 1993 396 249 147 22 140 1994 232 145 87 13 83 1995 150 82 68 10 39 1996 184 98 86 13 56 1997 192 64 129 19 43 1998 109 65 44 7 30 1999 115 67 48 7 34 2000 177 75 102 15 42 2001 172 72 100 15 43 36th SAW Consensus Summary 247
Table B2.8. Gulf of Maine winter flounder recreational landings (mt) by state.
Year ME NH MA total 1981 45 55 2,455 2,554 1982 2 20 1,855 1,876 1983 11 36 821 868 1984 5 68 1,227 1,300 1985 4 28 1,864 1,896 1986 112 21 390 523 1987 1 12 1,796 1,809 1988 0 15 329 345 1989 197 20 402 620 1990 265 5 100 370 1991 23 0 68 91 1992 16 13 61 90 1993 37 9 94 140 1994 2 12 68 83 1995 0 4 35 39 1996 0 5 51 56 1997 17 6 20 43 1998 1 12 18 30 1999 0 6 27 34 2000 0 4 37 42 2001 1 7 36 43 248 36th SAW Consensus Summary
Table B2.9. Percent Gulf of Maine winter flounder recreational landings (mt) by state.
Year ME NH MA 1981 2% 2% 96%
1982 0% 1% 99%
1983 1% 4% 95%
1984 0% 5% 94%
1985 0% 1% 98%
1986 21% 4% 75%
1987 0% 1% 99%
1988 0% 4% 95%
1989 32% 3% 65%
1990 72% 1% 27%
1991 25% 0% 75%
1992 18% 14% 67%
1993 27% 6% 67%
1994 3% 15% 82%
1995 0% 11% 89%
1996 0% 9% 91%
1997 40% 13% 46%
1998 2% 38% 60%
1999 0% 19% 81%
2000 0% 10% 90%
2001 1% 15% 83%
36th SAW Consensus Summary 249
Table B2.10. Gulf of Maine winter flounder recreational landing (mt) by halfyear.
Year halfyear 1 halfyear 2 total 1981 1,407 1,148 2,554 1982 517 1,359 1,876 1983 455 413 868 1984 599 701 1,300 1985 1,742 154 1,896 1986 485 39 523 1987 415 1,393 1,809 1988 211 134 345 1989 127 493 620 1990 52 318 370 1991 39 52 91 1992 24 66 90 1993 50 91 140 1994 38 45 83 1995 27 13 39 1996 39 17 56 1997 32 11 43 1998 15 15 30 1999 23 11 34 2000 14 28 42 2001 26 17 43 250 36th SAW Consensus Summary
Table B2.11. Percent Gulf of Maine winter flounder recreational landing by halfyear.
year halfyear 1 halfyear 2 1981 55% 45%
1982 28% 72%
1983 52% 48%
1984 46% 54%
1985 92% 8%
1986 93% 7%
1987 23% 77%
1988 61% 39%
1989 20% 80%
1990 14% 86%
1991 43% 57%
1992 27% 73%
1993 36% 64%
1994 46% 54%
1995 68% 32%
1996 69% 31%
1997 74% 26%
1998 50% 50%
1999 67% 33%
2000 33% 67%
2001 60% 40%
36th SAW Consensus Summary 251
Table B2.12. Number of lengths, samples, and metric tons per sample for Gulf of Maine winter flounder. Number of samples and calculations of metric tons per samples does not include observer data or gillnet landings from 1990-2001. * = redistributed according to market category and halfyear proportions. Bold are lengths from observer trawl data.
Number of lengths. Number of samples mt/samples year Qtr lg sm med un total lg sm Med un total lg sm med un total 1982 1 296 1 3 2 102 101 159 2 1 1 1 838 453 46 3 84 81 106 3 1 1 1 4 929 4 9 396 691 231 310 1983 1 80 99 1 1 1 2 300 100 407 2 3 1 4 120 510 53 3 108 388 3 1 3 4 107 956 106 2651 4 1 8 1 24 125 44 64 95 87 1984 1 201 209 1 2 2 2 237 294 221 2 3 2 2 74 95 3 123 3 1 4 126 690 100 2201 4 1 5 1 19 189 67 114 124 89 1985 1 273 565 1 3 3 2 392 170 2 3 2 54 3 105 3 1 4 116 80 1701 4 1 1 14 87 182 176 113 1986 1 266 1 3 2 237 109 109 2 3 1 1 242 126 48 3 111 86 3 1 1 4 389 107 89 1503 4 5 1 1 17 113 37 31 56 70 1987 1 113 1 1 2 2 3 95 3 1 4 47 156 272 683 4 1 2 3 8 257 137 75 249 143 1988 1 258 311 1 3 3 2 102 395* 2 1 4* 108 23 3 3 4 169 107* 1342 4 2 1* 14 340 164 96 89 1989 1 100 1 1 2 113 91 134 2 1 1 168 3 95 120 32 3 1 1 4 100 785 4 1 6 313 435 42 254 209 1990 1 328 301 1 3 4 2 102 2 1 64 48 3 3 4 117 197 97 1142 4 1 2 1 12 83 90 138 118 75 252 36th SAW Consensus Summary
Table B2.12 Continued.
Number of lengths. Number of samples mt/samples Year qtr lg sm med un total lg sm med un total lg sm med un total 1991 1 100 51 105 101 1 1 1 1 1 2 88 203 100 42 2 1 2 1 92 72 3 95 3 1 4 236 254 1375 4 3 3 15 32 47 95 115 65 1992 1 110 107 1 1 2 136 100 93 2 2 1 1 47 119 84 3 3 4 57 74 253 930 4 1 1 3 10 75 134 19 67 1993 1 100 1 1 2 288 2 3 83 16 3 55 91 3 1 4 80 157 51 822 4 1 2 8 47 177 30 59 1994 1 1 2 71 92 102 2 1 1 1 75 3 3 4 94 235 594 4 1 3 7 112 143 15 60 62 1995 1 101 175 63 1 1 2 2 299 2 3 37 3 414 3 4 4 609 1661 4 10 134 42 55 1996 1 77 1 1 2 231 2 2 44 3 355 252 3 2 3 4 84 440 86 112 1637 4 1 5 1 15 80 16 18 29 1997 1 204 1 2 2 127 75* 2 2 1* 28 66 3 220 218 3 2 3 4 307 502 56* 1709 4 4 8 1* 23 25 11 14 19 1998 1 148 79 1 2 1 2 151 201* 2 3 2* 34 29 3 583 3 7 4 69 163 110* 1504 4 1 2 1* 19 65 14 30 25 1999 1 104 1 1 2 171 2 2 3 28 3 1 4 52 408 763 4 1 5 26 10 34 36th SAW Consensus Summary 253
Table B2.12. Continued.
Number of lengths. Number of samples mt/samples year qtr lg sm med un total lg sm med un total lg sm med un total 2000 1 866 143 480 1 12 2 2 3441 51 554 2 45 1 1 3 102 50 3 2 4 114 26 5827 4 2 64 12 13 4 2001 1 187 172 1 2 2 99 157 189 630 2 1 2 3 37 10 3 100 52 399 3 1 1 4 154 198 1307 3644 4 2 2 14 26 21 24 32 254 36th SAW Consensus Summary
Table B2.13. Number of kept observer lengths, trips, and gillnet metric tons landed per 100 lengths sampled for Gulf of Maine winter flounder.
gillnet Year half lengths trips landings (mt) mt/100 lengths 1990 1 539 90 184 2 78 1 29 617 91 214 35 1991 1 126 6 81 2 30 8 13 156 14 94 60 1992 1 1950 39 134 2 172 25 26 2122 64 160 8 1993 1 2004 63 96 2 375 20 42 2379 83 138 6 1994 1 330 22 101 2 206 10 15 536 32 115 21 1995 1 1116 20 217 2 306 23 35 1422 43 253 18 1996 1 1275 26 146 2 118 17 19 1393 43 164 12 1997 1 793 18 139 2 42 4 27 835 22 166 20 1998 1 1162 19 141 2 431 8 32 1593 27 173 11 1999 1 747 5 78 2 526 12 7 1273 17 85 7 2000 1 911 8 85 2 261 4 15 1172 12 100 9 2001 1 862 15 94 2 42 2 32 904 17 126 14 36th SAW Consensus Summary 255
Table B2.14. Gulf of Maine winter flounder numbers of fish aged.
NEFSC MA DMF Commercial Year landings Spring Fall Spring Fall 1982 483 68 94 133 1983 1182 150 104 159 1984 908 63 150 139 1985 318 135 160 97 1986 344 84 62 57 1987 130 118 67 125 1988 249 127 68 104 7 1989 148 60 88 320 1990 241 122 111 224 1991 262 174 179 333 1992 270 144 148 362 1993 183 91 107 172 1994 139 122 134 253 149 1995 248 170 55 213 221 1996 246 97 181 324 1997 295 103 189 286 1998 341 122 75 135 1999 149 171 194 146 2000 883 176 216 160 2001 246 154 118 166 256 36th SAW Consensus Summary
Table B2.15. Gulf of Maine winter flounder discard ratios and number of trips/tows in the observer and VTR data for the large mesh, small mesh and gillnet fishery.
Large Mesh Otter Trawl Small Mesh Otter Trawl Gillnet Year Half-year # trips #tows SS ratio VTR trips VTR ratio # trips #tows SS ratio VTR trips VTR ratio # trips #tows SS ratio VTR trips VTR ratio 1989Jan-Jun 15 44 0.130 2 3 0.200 Jul-Dec 7 16 0.071 10 25 0.290 26 62 0.084 1990Jan-Jun 5 6 0.167 50 164 0.166 Jul-Dec 6 14 0.287 2 3 0.333 33 63 0.223 1991Jan-Jun 8 25 0.072 4 14 0.029 73 164 0.164 Jul-Dec 23 103 0.055 8 18 1.152 321 618 0.142 1992Jan-Jun 21 48 0.098 1 1 0.000 257 617 0.130 Jul-Dec 6 22 0.039 3 11 0.068 224 397 0.114 1993Jan-Jun 1 1 0.600 196 576 0.150 Jul-Dec 4 12 0.080 3 10 0.153 97 198 0.107 1994Jan-Jun 1 1 0.000 445 0.053 23 0.151 43 101 0.174 249 0.229 Jul-Dec 1422 0.062 524 0.092 15 35 0.103 648 0.091 1995Jan-Jun 4 15 1.101 2417 0.048 229 0.217 18 54 0.285 907 0.150 Jul-Dec 3 52 0.011 1149 0.037 22 57 123 0.322 19 52 0.201 548 0.388 1996Jan-Jun 2 5 0.068 2196 0.044 1 1 60 0.254 17 62 0.128 589 0.159 Jul-Dec 2 19 0.013 1227 0.035 26 93 3.344 219 1.807 18 39 0.066 364 0.553 1997Jan-Jun 3 13 0.231 1700 0.034 1 4 0.218 22 0.064 18 56 0.245 470 0.112 Jul-Dec 887 0.023 149 0.136 10 22 0.272 291 0.087 1998Jan-Jun 5 16 0.233 1809 0.046 17 0.046 27 87 0.109 543 0.144 Jul-Dec 939 0.030 129 0.024 35 66 0.049 329 0.117 1999Jan-Jun 942 0.038 15 0.034 14 41 0.141 285 0.136 Jul-Dec 15 35 0.015 1148 0.038 13 35 123 0.516 23 60 0.100 359 0.090 2000Jan-Jun 35 78 0.041 1240 0.060 7 10 0.123 28 0.192 27 74 0.137 378 0.094 Jul-Dec 6 8 0.000 1418 0.032 6 13 0.170 52 0.165 18 39 0.098 472 0.088 2001Jan-Jun 27 61 0.100 1289 0.029 3 0.054 13 27 0.061 340 0.095 Jul-Dec 51 129 0.037 1272 0.045 2 3 0.000 88 0.052 9 21 0.101 523 0.107 36th SAW Consensus Summary 257
Table B2.16. Gulf of Maine winter flounder discard lengths from observer data. MADMF observer length data in the small mesh otter trawl was also added to the table (6 tows, 2 trips, and 213 lengths in 1994; 55 tows, 20 trips, and 891 lengths in 1999; 20 tows, 8 trips, and 637 lengths in 2000).
large-mesh trawl small mesh otter trawl shrimp fishery gillnet YEAR H1 H2 H1 H2 H1 H2 H1 H2 1989tows 13 13 7 7 12 2 14 1 1 trips 9 9 4 4 6 1 7 1 1 lengths 116 116 239 239 347 79 426 2 2 1990tows 0 0 3 3 20 1 21 trips 0 0 3 3 10 1 11 lengths 0 0 126 126 313 18 331 1991tows 1 1 0 32 32 3 2 5 trips 1 1 0 15 15 3 1 4 lengths 9 9 0 1144 1144 20 2 22 1992tows 1 1 0 72 72 39 9 48 trips 1 1 0 24 24 30 7 37 lengths 18 18 0 1026 1026 352 32 384 1993tows 2 2 3 3 132 2 134 35 20 55 trips 2 2 2 2 53 1 54 20 14 34 lengths 12 12 43 43 1685 2 1687 400 38 438 1994tows 0 6 6 106 3 109 18 4 22 trips 0 2 2 49 3 52 10 3 13 lengths 0 213 213 1002 5 1007 136 6 142 1995tows 2 9 11 21 21 85 13 98 23 12 35 trips 1 2 3 12 12 45 7 52 14 8 22 lengths 28 18 46 264 264 1118 34 1152 377 38 415 1996tows 2 2 1 59 60 36 6 42 16 2 18 trips 1 1 1 21 22 17 3 20 7 2 9 lengths 5 5 1 250 251 197 105 302 89 2 91 1997tows 1 1 0 13 13 9 9 trips 1 1 0 7 7 3 3 lengths 2 2 0 155 155 67 67 1998tows 0 0 0 17 2 19 trips 0 0 0 9 2 11 lengths 0 0 0 70 5 75 1999tows 0 71 71 0 10 15 25 trips 0 30 30 0 5 7 12 lengths 0 1195 1195 0 163 53 216 2000tows 5 5 3 21 24 0 11 1 12 trips 3 3 3 9 12 0 6 1 7 lengths 90 90 9 640 649 0 219 1 220 2001tows 1 9 10 0 0 5 5 trips 1 4 5 0 0 3 3 lengths 8 184 192 0 0 42 42 258 36th SAW Consensus Summary
Table B2.17. Discard ratios and estimated discards (mt) for large mesh trawl VTR data and gillnet observer data. A 50%
mortality rate was applied to the total discard estimate. Discard estimates using the survey method for otter trawl is also shown for comparison. Gillnet ratio from 1986-1988 is the average from 1989-1993.
large mesh trawl vtr trawl survey trawl observer gillnet discards year vtr ratio discards (mt) discards (mt) Gillnet ratio (mt) 1982 - - 343 - -
1983 - - 112 - -
1984 - - 67 - -
1985 - - 93 - -
1986 - - 63 0.136 11 1987 - - 81 0.136 9 1988 - - 106 0.136 11 1989 - - 86 0.084 6 1990 - - 81 0.173 18 1991 - - 84 0.152 7 1992 - - 56 0.129 10 1993 - - 11 0.144 10 1994 0.061 13 65 0.165 9 1995 0.043 11 100 0.257 32 1996 0.040 8 72 0.119 10 1997 0.028 6 62 0.247 20 1998 0.038 9 53 0.100 8 1999 0.038 3 13 0.127 5 2000 0.041 6 19 0.133 7 2001 0.036 8 39 0.065 4 36th SAW Consensus Summary 259
Table B2.18. Gulf of Maine winter flounder estimated discard ratios in the shrimp fishery (total discard kg / total days fished estimated from NEFSC and MA Observer data by shrimp season). Ratio for 1982-1988 is the average ratio from 1989-1992. Total shrimp fishery days fished estimated by Wigley et al 1999 and estimated discards are also shown. A 50% mortality is used for estimating dead discards. Dotted line indicates the introduction of the Nordmore grate.
Year trips tows ratio Shrimp df discard wt (mt) dead discards (mt) 1982 22.225 970.1 22 11 1983 22.225 1156.9 26 13 1984 22.225 1754.0 39 19 1985 22.225 2081.4 46 23 1986 22.225 2395.1 53 27 1987 22.225 3708.2 82 41 1988 22.225 2815.2 63 31 1989 12 24 13.361 2839.5 38 19 1990 25 53 24.070 3204.6 77 39 1991 38 94 27.720 2587.7 72 36 1992 72 225 23.749 2313.3 55 27 1993 63 178 10.730 1902.2 20 10 1994 63 183 7.320 1982.3 15 7 1995 58 136 7.382 3375.7 25 12 1996 40 92 6.290 3242.9 20 10 1997 21 55 12.511 3661.2 46 23 1998 3 6 10.559 2204.0 23 12 1999 4 5 5.645 1217.4 7 3 2000 4 10 10.927 792.9 9 4 2001 3 6 9.749 672.8 7 3 260 36th SAW Consensus Summary
Table B2.19. Gulf of Maine winter flounder commercial numbers (000s) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 550 2,025 1,288 733 482 181 22 1983 5 366 1,026 1,311 632 282 109 68 21 13 7 2 1 1984 599 1,512 982 384 235 152 76 44 7 1 1985 25 573 1,164 759 263 82 64 26 5 5 1986 310 629 512 303 199 58 28 12 4 1 1987 283 821 422 356 141 25 35 2 0 1988 327 745 725 217 94 49 46 5 1 1989 37 840 733 602 102 8 7 1990 102 478 690 446 145 43 11 5 2 1991 175 735 519 191 104 45 28 1 1992 188 609 511 174 57 20 7 2 1993 2 105 605 545 77 46 4 1994 4 386 557 130 31 7 1995 8 267 680 456 162 21 14 2 1996 107 693 347 61 11 1 2 1 1997 93 512 455 105 27 4 2 1998 25 217 458 321 105 34 4 1 1999 49 158 143 59 19 5 4 2000 1 57 212 173 50 14 7 1 2001 2 27 287 390 175 63 26 6 3 Table B2.20. Gulf of Maine winter flounder commercial weight (kg) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 0.351 0.454 0.502 0.617 0.817 0.901 1.087 1.330 1983 0.293 0.281 0.403 0.528 0.667 0.814 0.970 1.062 1.238 1.415 1.467 1.224 1.422 1984 0.294 0.301 0.392 0.550 0.763 0.971 1.124 1.124 1.275 1.578 1985 0.307 0.366 0.449 0.572 0.802 1.020 1.121 1.183 1.071 1.462 1986 0.412 0.470 0.534 0.699 0.842 0.940 1.231 1.387 0.479 2.996 1987 0.380 0.437 0.586 0.650 0.843 1.107 1.272 1.684 1988 0.510 0.524 0.530 0.669 0.620 0.976 1.082 1.132 2.338 1.619 1989 0.286 0.434 0.542 0.592 1.034 1.155 1.264 1990 0.435 0.482 0.541 0.646 0.780 1.039 1.261 1.214 1.310 1991 0.393 0.487 0.626 0.624 0.725 0.741 0.896 1.810 1992 0.364 0.447 0.569 0.653 0.787 1.075 1.461 1.745 1993 0.125 0.336 0.396 0.457 0.701 0.607 1.331 1994 0.274 0.402 0.489 0.669 0.829 1.324 1.558 1995 0.305 0.369 0.437 0.552 0.653 1.030 1.181 1.447 2.572 1996 0.387 0.451 0.546 0.634 0.915 1.452 1.694 2.177 2.663 1997 0.412 0.451 0.540 0.701 0.847 0.998 1.479 1998 0.371 0.426 0.482 0.598 0.750 0.991 1.709 2.149 2.459 1999 0.431 0.503 0.564 0.735 0.962 1.102 1.236 2.941 2000 0.449 0.400 0.480 0.560 0.711 0.930 1.178 1.467 1.555 2001 0.175 0.373 0.468 0.546 0.693 0.869 0.953 1.215 1.562 36th SAW Consensus Summary 261
Table B2.21. Gulf of Maine winter flounder recreational numbers (000's) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 40 1,546 2,526 2,180 669 135 95 22 38 6 5 7 3 1983 89 381 654 488 224 80 49 12 4 6 1984 12 166 423 847 468 112 159 50 37 10 1985 112 762 875 1,163 136 136 37 1986 18 102 301 56 154 44 18 1987 28 805 739 436 170 113 37 52 9 1988 2 10 103 320 142 153 75 30 3 3 1989 124 469 729 172 110 43 21 7 2 1990 111 228 236 37 25 5 5 3 2 1 1991 9 31 47 34 12 9 7 3 1 1992 10 29 50 26 9 5 1 3 3 1993 21 54 79 66 20 5 3 1994 4 32 55 30 13 7 5 1995 2 22 27 19 8 3 2 1996 17 40 17 11 7 5 1 1997 8 20 18 5 5 5 3 1 1998 2 19 32 8 4 1999 8 23 17 11 4 5 1 2000 10 23 26 11 4 1 1 2001 8 22 16 14 12 Table B2.22. Gulf of Maine winter flounder recreational mean weights (kg) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 0.109 0.197 0.339 0.479 0.571 0.746 1.025 1.522 1.929 2.801 3.431 3.963 5.187 1983 0.131 0.258 0.331 0.444 0.578 0.730 0.893 0.959 1.395 1.365 1984 0.098 0.256 0.349 0.419 0.539 0.594 0.745 1.073 0.932 1.784 1985 0.196 0.293 0.456 0.592 0.823 0.872 1.047 1986 0.201 0.312 0.497 0.563 0.776 1.090 1.187 1987 0.138 0.417 0.510 0.724 0.871 1.062 1.195 1.252 1.784 1988 0.098 0.254 0.372 0.464 0.620 0.838 1.053 1.359 1.600 0.000 0.976 1989 0.277 0.432 0.630 0.762 0.981 1.179 1.298 1.781 1.547 0.000 1990 0.268 0.425 0.644 0.642 0.770 0.678 1.317 1.078 1.257 1.199 1991 0.360 0.375 0.460 0.569 0.708 0.916 0.993 1.307 0.616 1992 0.224 0.358 0.466 0.636 0.886 1.013 1.199 1.576 1.365 1993 0.282 0.381 0.482 0.626 0.848 0.997 1.453 1994 0.275 0.386 0.477 0.558 0.701 0.908 1.009 1995 0.284 0.393 0.446 0.552 0.621 0.644 0.872 1996 0.317 0.398 0.434 0.516 0.616 0.766 0.958 0.000 1.744 1997 0.271 0.428 0.426 0.471 0.545 0.619 0.690 0.765 0.869 1998 0.293 0.325 0.419 0.572 0.753 1999 0.383 0.446 0.520 0.595 0.666 0.922 0.669 2000 0.449 0.496 0.529 0.567 0.668 0.616 0.983 1.047 2001 0.347 0.405 0.521 0.640 0.689 262 36th SAW Consensus Summary
Table B2.23. Gulf of Maine winter flounder recreational discards (000's) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 25 105 9 1983 17 7 3 1984 5 14 10 1985 12 30 28 1 1986 20 13 4 1 1987 29 39 32 2 1988 3 6 7 1 1989 13 23 7 1 1990 3 14 4 1991 2 4 3 1 1992 3 2 1 1993 5 12 4 1 1994 2 7 3 1 1995 2 4 3 1 1996 3 5 3 1 1997 2 9 6 2 1998 2 3 2 1999 2 3 2 1 2000 4 6 4 2 2001 3 4 5 3 1 Table B2.24. Gulf of Maine winter flounder recreational discards (kg) at age.
Year 1 2 3 3 4 5 6 7 8 9 11 12 13 1982 0.041 0.084 0.116 1983 0.071 0.087 0.128 1984 0.072 0.072 0.117 1985 0.041 0.083 0.171 0.210 1986 0.078 0.161 0.209 0.258 0.295 1987 0.043 0.088 0.216 0.307 1988 0.059 0.120 0.177 0.279 1989 0.055 0.158 0.228 0.285 0.325 1990 0.043 0.123 0.199 0.259 0.325 1991 0.055 0.108 0.210 0.288 0.325 1992 0.048 0.132 0.236 0.277 0.307 1993 0.048 0.108 0.184 0.286 0.293 1994 0.059 0.111 0.201 0.251 0.299 1995 0.055 0.127 0.207 0.239 0.325 1996 0.046 0.117 0.217 0.268 0.271 1997 0.042 0.092 0.170 0.247 0.287 1998 0.037 0.114 0.190 0.269 0.325 1999 0.051 0.103 0.207 0.245 0.314 2000 0.074 0.158 0.211 0.272 0.297 2001 0.042 0.098 0.208 0.261 0.285 36th SAW Consensus Summary 263
Table B2.25. Gulf of Maine winter flounder commercial large mesh trawl discards (000's) at age using vtr ratios.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 40 642 697 18 1983 18 124 249 36 1984 3 87 97 59 3 1985 4 59 196 77 3 1986 1 77 143 23 9 1987 1 20 236 49 1 1988 3 61 233 107 3 1 1989 2 118 105 71 19 6 1990 1 86 162 49 17 1991 5 70 147 89 5 1992 2 56 105 45 8 1993 1 14 20 9 2 1994 1 10 22 13 4 1995 1 5 21 14 1 1996 2 7 12 8 1 1997 5 9 6 2 1998 7 14 9 3 1999 2 5 3 1 2000 0 3 7 5 3 1 2001 2 8 10 4 2 Table B2.26. Gulf of Maine winter flounder commercial large mesh trawl discards weight (kg) at age using vtr ratios.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 0.095 0.212 0.282 0.368 0.560 0.640 0.943 1.259 1.625 2.284 1983 0.122 0.247 0.264 0.370 0.514 0.458 0.648 1.252 1.422 1984 0.091 0.223 0.278 0.322 0.350 0.595 0.699 0.954 1.014 1985 0.114 0.221 0.273 0.318 0.414 0.595 0.761 1.093 1.713 1986 0.038 0.182 0.275 0.317 0.301 0.508 0.815 1.014 1.422 1987 0.045 0.125 0.260 0.324 0.424 0.699 1.038 1.362 1.612 1988 0.068 0.210 0.249 0.314 0.388 0.410 0.768 1.029 1.432 1.619 1989 0.056 0.229 0.280 0.289 0.351 0.336 0.594 1.249 0.000 1990 0.040 0.216 0.254 0.300 0.353 0.468 0.949 1.178 0.949 1.248 1991 0.101 0.220 0.264 0.305 0.379 0.411 0.589 0.876 1.349 1.746 1992 0.067 0.202 0.264 0.315 0.332 0.419 0.824 1.258 1.617 1993 0.069 0.202 0.243 0.306 0.348 0.494 0.751 1.377 1.533 1994 0.060 0.160 0.255 0.320 0.345 0.518 0.956 1995 0.045 0.152 0.249 0.319 0.390 0.499 0.249 1.351 1.515 1996 0.077 0.214 0.286 0.333 0.359 0.507 0.642 1.176 1997 0.046 0.174 0.277 0.312 0.346 0.514 0.538 0.751 1998 0.030 0.146 0.261 0.328 0.363 0.542 0.890 1.106 1999 0.061 0.157 0.280 0.339 0.395 0.481 1.033 1.195 1.457 2000 0.094 0.205 0.270 0.309 0.367 0.382 0.468 0.878 1.105 2001 0.038 0.159 0.292 0.329 0.354 0.368 0.527 0.592 0.813 1.333 264 36th SAW Consensus Summary
Table B2.27. Gulf of Maine winter flounder gillnet discards (000's) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1986 3 26 9 3 1987 27 6 1988 27 13 1989 14 7 1990 1 39 28 2 1991 2 17 7 1 1992 3 28 6 1993 1 25 10 1 1994 1 22 11 2 1995 6 37 23 12 5 3 1 1996 2 21 10 2 1997 1 26 30 13 1998 3 14 8 2 1 1999 2 2 1 2 1 1 2000 1 8 7 4 1 2001 4 5 2 1 Table B2.28. Gulf of Maine winter flounder gillnet discard weight (kg) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1986 0.182 0.276 0.294 0.274 0.593 1987 0.154 0.265 0.306 0.503 0.693 1988 0.106 0.261 0.292 0.476 0.543 1989 0.122 0.259 0.295 0.363 0.346 0.693 1990 0.143 0.249 0.278 0.338 1991 0.200 0.269 0.298 0.341 1992 0.196 0.283 0.311 0.360 0.409 1993 0.174 0.264 0.287 0.307 0.631 1994 0.172 0.246 0.295 0.313 0.538 1995 0.112 0.246 0.285 0.358 0.546 0.636 0.600 0.824 1996 0.207 0.268 0.286 0.309 0.793 0.812 1997 0.222 0.265 0.299 0.333 1998 0.172 0.232 0.305 0.475 0.568 0.761 0.693 1999 0.184 0.277 0.372 0.540 0.684 0.793 0.786 1.132 1.484 2000 0.185 0.260 0.296 0.363 0.403 0.607 0.837 0.789 2001 0.267 0.315 0.323 0.401 0.812 0.812 0.812 36th SAW Consensus Summary 265
Table B2.29. Gulf of Maine winter flounder commercial shrimp fishery discards (000's) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 13 65 16 1 1983 17 62 37 4 1984 15 83 55 19 1 1985 39 94 57 7 1986 62 137 32 8 2 1987 48 182 110 7 1988 44 103 101 13 1989 42 136 45 4 1990 35 53 86 33 7 1991 36 145 62 12 1 1992 46 177 30 3 1993 38 67 17 4 1 1994 30 73 11 1 1995 41 70 19 4 1996 52 52 13 5 1 1997 34 171 44 7 1998 41 61 16 3 1 1999 16 18 4 1 2000 19 22 11 2 1 2001 17 16 5 2 Table B2.30. Gulf of Maine winter flounder shrimp fishery weight (kg) at age.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 1982 0.025 0.093 0.212 0.341 0.429 1983 0.023 0.074 0.183 0.322 0.505 0.400 0.522 1984 0.016 0.067 0.151 0.273 0.357 0.502 0.453 1985 0.034 0.094 0.188 0.293 0.470 0.000 1986 0.035 0.107 0.234 0.308 0.316 0.469 1987 0.028 0.081 0.197 0.343 0.470 0.519 1988 0.028 0.078 0.170 0.291 0.400 0.353 1989 0.029 0.079 0.191 0.277 0.393 1990 0.039 0.093 0.201 0.316 0.397 0.442 1991 0.040 0.106 0.208 0.297 0.336 0.460 1992 0.028 0.097 0.217 0.296 0.361 0.076 1993 0.025 0.064 0.187 0.295 0.427 0.621 0.953 1994 0.026 0.066 0.145 0.286 0.413 0.603 0.767 1995 0.042 0.091 0.186 0.224 0.579 0.426 0.221 0.795 1996 0.029 0.084 0.214 0.299 0.277 0.377 1997 0.043 0.076 0.155 0.245 0.329 0.117 0.170 1998 0.037 0.088 0.162 0.299 0.440 0.568 0.687 0.974 1999 0.033 0.078 0.196 0.219 0.400 0.569 0.866 0.810 0.933 2000 0.031 0.065 0.122 0.258 0.355 0.424 0.633 0.937 0.943 2001 0.032 0.068 0.163 0.240 0.300 0.431 0.683 0.931 0.751 0.920 266 36th SAW Consensus Summary
Table B2.31. Gulf of Maine winter flounder composition of the catch by number.
Landings Discards year recreational commercial recreational gillnet lg mesh shrimp Total 1982 7,274 5,282 140 0 1,397 96 14,188 1983 1,988 3,842 27 0 428 120 6,406 1984 2,285 3,992 29 0 249 174 6,729 1985 3,220 2,965 71 0 340 197 6,793 1986 691 2,055 38 41 253 240 3,318 1987 2,391 2,086 102 34 308 346 5,266 1988 841 2,210 17 40 406 262 3,775 1989 1,678 2,329 44 21 321 227 4,620 1990 652 1,922 20 70 315 214 3,193 1991 154 1,799 9 26 315 257 2,559 1992 137 1,567 7 36 216 256 2,220 1993 249 1,384 22 36 45 127 1,863 1994 145 1,116 13 36 49 116 1,475 1995 82 1,609 10 85 42 134 1,963 1996 98 1,224 13 35 31 123 1,524 1997 64 1,198 19 70 23 257 1,630 1998 65 1,166 7 29 33 123 1,423 1999 67 437 7 9 11 39 571 2000 75 516 15 22 20 54 701 2001 72 980 15 13 26 41 1,146 Table B2.32. Gulf of Maine winter flounder composition of the catch by weight (mt).
Landings Discards year recreational commercial recreational gillnet lg mesh shrimp Total 1982 1,876 2,793 11 343 11 5,034 1983 868 2,096 2 112 13 3,091 1984 1,300 1,699 2 67 19 3,089 1985 1,896 1,582 8 93 23 3,602 1986 523 1,188 5 11 63 27 1,817 1987 1,809 1,140 12 9 81 41 3,091 1988 345 1,250 2 11 106 31 1,745 1989 620 1,253 6 6 86 19 1,989 1990 370 1,116 3 18 81 39 1,626 1991 91 1,008 1 7 84 36 1,227 1992 90 825 1 10 56 27 1,009 1993 140 611 3 10 11 10 785 1994 83 552 2 9 13 7 666 1995 39 796 1 32 11 12 892 1996 56 600 2 10 8 10 686 1997 43 618 2 20 6 23 712 1998 30 637 1 8 9 12 697 1999 34 253 1 5 3 3 300 2000 42 382 2 7 6 4 443 2001 43 571 2 4 8 3 632 36th SAW Consensus Summary 267
Table B2.33. Gulf of Maine winter flounder total catch at age (000's).
Year 1 2 3 4 5 6 7 8+
1982 118 2,909 5,274 3,487 1,402 617 276 104 1983 146 941 1,970 1,839 857 362 158 133 1984 36 949 2,097 1,907 856 348 312 225 1985 54 320 1,617 2,124 1,925 398 218 136 1986 83 557 936 852 373 353 102 62 1987 78 553 2,031 1,224 794 311 138 136 1988 52 507 1,215 1,179 361 248 123 89 1989 56 439 1,480 1,545 793 218 51 38 1990 39 366 997 1,037 509 170 48 29 1991 43 405 995 674 232 116 55 40 1992 52 436 802 615 208 67 24 16 1993 46 220 725 647 147 66 9 3 1994 33 98 477 638 166 44 14 5 1995 43 95 367 749 488 174 27 18 1996 57 174 758 413 83 23 8 9 1997 37 279 605 519 139 32 9 11 1998 44 100 283 511 335 109 36 5 1999 18 23 70 188 162 71 24 16 2000 23 33 97 251 206 62 18 11 2001 20 24 58 329 412 192 76 35 Table B2.34. Gulf of Maine winter flounder mean weight at age (kg).
Year 1 2 3 4 5 6 7 8+
1982 0.081 0.223 0.375 0.487 0.595 0.802 0.943 2.037 1983 0.115 0.252 0.357 0.502 0.644 0.795 0.946 1.164 1984 0.059 0.257 0.305 0.400 0.543 0.708 0.855 1.115 1985 0.041 0.169 0.311 0.447 0.584 0.809 0.927 1.122 1986 0.045 0.291 0.408 0.510 0.664 0.813 1.005 1.221 1987 0.034 0.240 0.390 0.527 0.690 0.858 1.070 1.284 1988 0.034 0.376 0.421 0.487 0.648 0.753 1.022 1.204 1989 0.036 0.197 0.412 0.570 0.623 0.989 1.175 1.397 1990 0.040 0.271 0.398 0.538 0.631 0.778 1.003 1.247 1991 0.048 0.256 0.429 0.563 0.609 0.722 0.771 0.965 1992 0.031 0.229 0.405 0.539 0.638 0.799 1.064 1.468 1993 0.031 0.226 0.380 0.454 0.658 0.680 1.148 1.453 1994 0.029 0.096 0.379 0.481 0.637 0.790 1.128 1.052 1995 0.043 0.127 0.345 0.431 0.552 0.651 0.929 1.186 1996 0.029 0.279 0.437 0.520 0.593 0.768 0.851 1.381 1997 0.043 0.191 0.415 0.514 0.630 0.802 0.798 0.859 1998 0.036 0.170 0.384 0.471 0.594 0.749 0.984 1.814 1999 0.035 0.088 0.391 0.490 0.559 0.713 0.907 1.062 2000 0.039 0.108 0.345 0.470 0.549 0.676 0.869 1.187 2001 0.033 0.090 0.317 0.454 0.542 0.685 0.840 1.055 268 36th SAW Consensus Summary
Table B2.35. Gulf of Maine winter flounder catch at age construction summary.
Catch at age component years halfyear length data age data Trawl and other 82-01 mix commercial and commercial commercial landings observer (unclassified) gillnet commercial 90-01 whole year observer (kept) commercial Landings recreational 82-01 halfyear MRFSS combine NEFSC and MA Landings DMF ages by halfyear recreational 82-01 halfyear spr & fall MA DMF combine NEFSC and MA Discards DMF ages by halfyear Large mesh trawl 82-93 whole year survey method combine NEFSC discards (survey) (spr & fall MA DMF) spr & fall survey Large mesh trawl 94-01 whole year survey method combine NEFSC discards (vtr/survey) (spr & fall MA DMF) spr & fall survey gillnet discards 86-01 whole year observer (discards) combine spr NEFSC and MA DMF ages shrimp discards 82-01 shrimp season observer (discards) combine spr NEFSC and MA DMF ages 36th SAW Consensus Summary 269
Table B2.36. NEFSC and MADMF stratified mean survey indices of abundance for Gulf of Maine winter flounder. NEFSC indices use offshore strata (26,27,38-40) and inshore strata (58-61,65,66). NEFSC indices are calculated with trawl door conversion factors where appropriate. MADMF uses strata 25-36.
NEFSC spring NEFSC fall MADMF spring MADMF fall year number weight number weight number weight number weight 1978 86.805 18.373 43.360 9.887 1979 9.063 3.218 6.003 2.602 64.952 14.407 119.506 28.978 1980 11.284 4.447 13.141 6.553 66.231 17.494 74.684 15.940 1981 13.051 3.946 4.179 3.029 100.569 28.370 47.342 13.228 1982 7.670 3.022 4.201 1.924 60.719 14.687 106.053 23.635 1983 12.367 5.653 10.304 3.519 108.508 27.233 88.143 15.772 1984 5.155 1.979 7.732 3.106 66.271 15.977 35.956 10.817 1985 3.469 1.418 7.638 2.324 48.651 13.594 44.564 7.381 1986 2.343 0.998 2.502 0.938 62.356 14.724 41.914 6.603 1987 5.609 1.503 1.605 0.488 83.171 17.648 50.426 7.227 1988 6.897 1.649 3.000 1.031 52.733 10.617 33.063 7.173 1989 3.717 1.316 6.402 2.013 63.595 13.317 33.983 7.462 1990 5.415 2.252 3.527 1.177 74.131 12.966 67.874 13.452 1991 4.517 1.436 7.035 1.467 49.265 11.587 88.777 15.473 1992 3.933 1.160 10.447 3.096 74.146 13.938 77.350 13.471 1993 1.556 0.353 7.559 1.859 80.133 12.390 92.476 14.996 1994 3.481 0.891 4.870 1.319 71.710 10.036 67.351 13.560 1995 12.185 3.149 4.765 1.446 87.848 14.560 84.768 17.250 1996 2.736 0.732 10.099 3.116 77.249 12.823 74.295 13.031 1997 2.806 0.664 10.008 2.950 95.918 14.796 74.347 14.316 1998 2.001 0.528 3.218 0.987 91.466 15.756 93.889 14.934 1999 6.510 1.982 10.921 3.269 77.941 14.198 117.648 22.672 2000 10.383 2.885 12.705 5.065 169.291 35.453 101.633 25.693 2001 5.242 1.666 8.786 3.131 90.153 23.891 80.978 18.367 2002 12.066 3.693 10.691 4.003 87.376 21.404 270 36th SAW Consensus Summary
Table B2.37. NEFSC spring stratified mean number per tow at age for Gulf of Maine winter flounder (offshore strata 26,27,38-40 and inshore 58-61,65,66).
Year 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 total 1980 0.10 3.28 4.73 1.79 0.96 0.31 0.06 0.05 11.28 1981 1.05 5.36 2.05 3.14 0.92 0.39 0.09 0.04 13.05 1982 0.16 1.92 3.40 0.85 1.00 0.11 0.06 0.10 0.03 7.67 1983 0.42 0.88 3.65 3.06 1.88 1.00 1.21 0.23 0.02 0.02 12.37 1984 0.23 1.13 1.37 1.17 0.61 0.08 0.35 0.03 0.16 0.02 5.15 1985 0.01 0.53 1.41 0.65 0.57 0.10 0.14 0.04 0.01 3.47 1986 0.03 0.75 0.42 0.58 0.14 0.31 0.10 0.02 2.34 1987 0.19 1.58 2.65 0.61 0.23 0.14 0.12 0.05 0.03 5.61 1988 0.65 1.36 3.04 1.42 0.26 0.11 0.03 0.03 6.90 1989 0.06 0.49 1.39 1.13 0.31 0.13 0.10 0.11 3.72 1990 0.04 0.61 1.63 1.54 0.78 0.34 0.04 0.17 0.14 0.14 5.42 1991 0.09 1.26 1.52 1.01 0.47 0.10 0.04 0.01 0.01 0.01 4.52 1992 0.31 1.16 1.01 0.96 0.34 0.10 0.03 0.01 0.01 3.93 1993 0.01 0.53 0.59 0.28 0.11 0.02 0.01 1.56 1994 0.02 1.00 1.28 0.78 0.29 0.08 0.01 0.01 3.48 1995 0.59 2.89 5.45 2.20 0.68 0.20 0.14 0.02 12.19 1996 0.05 0.59 1.05 0.74 0.23 0.06 0.01 2.74 1997 0.04 0.69 0.81 0.71 0.41 0.09 0.04 0.01 2.81 1998 0.10 0.59 0.60 0.48 0.21 0.01 0.01 2.00 1999 0.31 1.17 2.28 1.68 0.71 0.36 6.51 2000 0.16 1.50 3.76 2.41 1.56 0.75 0.17 0.04 0.02 10.38 2001 0.07 0.52 1.41 1.49 0.83 0.60 0.22 0.09 0.02 5.24 2002 0.20 1.59 2.98 3.57 2.29 0.92 0.34 0.11 0.07 12.07 36th SAW Consensus Summary 271
Table B2.38. NEFSC fall stratified mean number per tow at age for Gulf of Maine winter flounder (offshore strata 26,27,38-40 and inshore 58-61,65,66).
year 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 total 1980 0.57 4.36 5.34 1.85 0.74 0.18 0.05 0.05 13.14 1981 0.07 0.71 1.76 0.78 0.12 0.37 0.08 0.12 0.08 0.41 0.04 4.18 1982 0.30 1.21 1.68 0.40 0.32 0.08 0.21 4.20 1983 2.14 3.60 3.12 1.01 0.27 0.11 0.07 10.30 1984 0.45 2.34 1.67 2.17 0.59 0.22 0.17 0.11 7.73 1985 1.30 2.74 1.92 1.15 0.33 0.10 0.10 7.64 1986 0.02 0.73 1.15 0.49 0.05 0.02 0.01 0.02 2.50 1987 0.08 0.46 0.84 0.19 0.03 0.01 1.61 1988 0.49 0.96 0.60 0.71 0.15 0.06 0.03 3.00 1989 0.46 3.60 1.42 0.77 0.08 0.07 0.01 6.40 1990 0.10 1.86 1.09 0.41 0.04 0.02 0.02 3.53 1991 0.03 2.60 2.83 1.09 0.39 0.03 0.05 0.03 7.04 1992 1.92 3.70 2.40 1.63 0.75 0.01 0.03 10.45 1993 1.66 3.16 1.82 0.69 0.23 0.01 7.56 1994 0.43 2.32 1.29 0.65 0.12 0.03 0.03 4.87 1995 0.47 1.83 1.51 0.63 0.19 0.14 4.77 1996 0.01 1.77 2.37 2.57 2.63 0.60 0.13 0.01 10.10 1997 0.41 4.32 3.19 1.47 0.57 0.03 10.01 1998 0.19 0.92 1.13 0.78 0.14 0.06 3.22 1999 0.81 2.77 3.65 2.85 0.68 0.15 0.01 10.92 2000 0.62 2.03 4.00 3.54 1.41 0.96 0.15 12.70 2001 0.36 1.66 2.59 2.80 0.96 0.36 0.04 0.01 8.79 Table B2.39. MADMF spring stratified mean number per tow at age for Gulf of Maine winter flounder (strata 25-36).
year 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 total 1982 7.51 30.59 8.96 8.80 2.57 0.90 1.33 0.02 0.04 60.72 1983 0.07 14.01 32.31 30.65 18.11 8.82 2.36 1.02 0.84 0.28 0.02 108.51 1984 5.80 26.27 16.96 11.65 3.94 0.38 0.83 0.08 0.31 0.04 66.27 1985 9.47 7.29 15.34 11.28 3.57 1.39 0.25 0.03 0.03 48.65 1986 9.35 19.78 20.97 10.29 1.22 0.46 0.06 0.04 0.19 62.36 1987 16.93 18.71 32.69 11.54 0.72 1.74 0.33 0.02 0.49 83.17 1988 0.08 7.47 15.76 18.87 9.37 0.61 0.38 0.00 0.04 0.10 0.05 52.73 1989 9.15 23.03 17.39 9.10 3.72 0.71 0.13 0.23 0.15 63.59 1990 14.31 18.33 27.47 10.04 2.04 1.35 0.39 0.08 0.08 0.02 0.04 74.13 1991 4.82 19.21 13.00 7.84 3.17 0.50 0.24 0.17 0.11 0.15 0.04 49.27 1992 19.96 32.12 12.31 6.70 1.97 0.69 0.16 0.07 0.08 0.07 74.15 1993 17.86 37.10 15.09 6.46 2.03 1.09 0.34 0.02 0.11 0.04 80.13 1994 14.33 36.11 15.44 4.66 0.79 0.12 0.17 0.08 0.02 71.71 1995 0.06 20.76 36.25 22.59 6.02 1.33 0.54 0.15 0.11 0.02 0.02 87.85 1996 14.96 34.59 17.79 7.04 1.88 0.73 0.19 0.08 77.25 1997 15.04 39.94 22.78 10.72 5.34 1.08 0.58 0.26 0.09 0.06 0.03 95.92 1998 10.23 32.61 29.11 13.26 4.12 1.15 0.81 0.17 91.47 1999 14.31 25.96 21.79 9.02 4.66 1.14 0.57 0.44 0.05 77.94 2000 28.67 69.85 33.39 18.16 11.00 5.83 1.79 0.37 0.22 169.29 2001 14.37 11.22 29.56 19.47 7.23 4.79 2.34 0.68 0.33 0.16 90.15 2002 9.59 23.85 19.60 19.52 7.59 4.97 1.64 0.25 0.27 0.09 87.38 272 36th SAW Consensus Summary
Table B2.40. MADMF fall stratified mean number per tow at age for Gulf of Maine winter flounder (strata 25-36).
year 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 total 1980 0.13 27.26 31.13 14.18 1.54 0.38 0.01 0.04 74.68 1981 0.13 13.05 21.14 11.46 1.31 0.02 0.19 0.04 47.34 1982 0.44 42.30 39.70 19.00 3.62 0.63 0.30 0.04 0.02 106.05 1983 0.00 49.19 23.26 11.70 2.80 1.11 0.07 0.01 88.14 1984 0.06 8.29 11.63 6.41 6.89 1.80 0.59 0.25 0.02 35.96 1985 0.28 22.32 12.36 6.14 2.66 0.54 0.21 0.05 44.56 1986 0.23 16.68 14.78 8.44 1.46 0.24 0.00 0.04 0.04 41.91 1987 0.50 17.29 19.40 11.68 1.34 0.10 0.11 0.02 50.43 1988 0.16 11.96 12.69 3.87 3.09 0.80 0.34 0.11 0.04 33.06 1989 12.17 14.59 5.29 1.41 0.31 0.19 0.03 33.98 1990 8.35 45.03 11.72 2.54 0.18 0.03 0.03 67.87 1991 2.41 40.54 23.35 16.65 4.92 0.58 0.22 0.12 88.78 1992 0.65 38.61 18.43 10.65 5.87 2.58 0.11 0.44 77.35 1993 0.32 34.29 38.90 13.55 3.82 1.37 0.17 0.06 92.48 1994 0.12 17.93 28.24 14.66 5.00 1.08 0.14 0.14 0.05 67.35 1995 0.29 29.32 30.17 17.27 6.04 0.91 0.49 0.22 0.05 84.77 1996 1.01 33.45 16.23 13.19 8.53 1.51 0.37 74.30 1997 0.47 20.04 29.06 17.89 5.25 1.54 0.10 74.35 1998 0.34 38.17 28.88 16.86 7.30 1.71 0.63 93.89 1999 1.17 30.34 42.82 23.00 15.01 4.10 1.15 0.06 117.65 2000 0.30 25.54 30.64 23.79 13.65 4.34 2.43 0.94 101.63 2001 0.20 27.85 17.67 14.22 14.96 4.13 1.71 0.22 0.01 80.98 Table B2.41. Seabrook spring mean number per tow at age for Gulf of Maine winter flounder.
year 1 2 3 4 5 6 7 8 9 10 11 total 1985 1.16 0.49 0.40 0.21 0.08 0.04 0.02 2.39 1986 1.65 1.06 0.52 0.23 0.06 0.01 3.53 1987 1.60 1.47 1.08 0.15 0.01 0.08 0.03 0.01 4.43 1988 0.88 1.18 1.52 0.31 0.02 0.02 3.92 1989 3.73 1.30 1.35 0.37 0.06 0.03 0.01 6.85 1990 1.63 1.06 0.93 0.40 0.08 0.02 0.01 4.14 1991 2.66 1.19 1.19 0.37 0.12 0.02 5.55 1992 0.58 1.00 0.34 0.16 0.02 2.11 1993 1994 0.81 1.16 0.32 0.05 2.33 1995 0.97 0.97 0.38 0.09 0.02 0.01 2.44 1996 1.38 1.35 0.63 0.11 0.03 0.01 3.51 1997 0.94 1.29 0.59 0.21 0.08 0.02 0.01 0.01 3.15 1998 1.39 2.62 1.67 0.56 0.17 0.04 0.01 0.01 0.02 6.50 1999 3.13 3.94 2.49 0.39 0.12 0.02 0.01 0.03 10.14 2000 3.32 6.72 1.53 0.38 0.23 0.10 0.03 0.01 0.01 12.31 2001 2.74 0.97 1.76 0.32 0.06 0.03 0.02 5.91 36th SAW Consensus Summary 273
Table B2.42. Age and length at 50% maturity for Gulf of Maine winter flounder in the spring NEFSC, MADMF, and combined surveys with the sexes combined.
NEFSC MADMF Both time period total N L50 A50 total N L50 A50 total N L50 A50 81-85 456 23.7 2.5 479 29.1 3.5 935 26.6 2.9 86-90 510 21.3 2.3 763 28.5 3.4 1,273 25.4 3.0 91-95 700 24.2 2.8 1,312 28.4 3.2 2,012 26.8 3.0 96-01 823 22.8 2.6 1,212 27.7 3.3 2,035 25.3 3.0 81-01 2,489 23.1 2.6 3,766 28.3 3.3 6,255 26.0 3.0 Table B2.43. Age at 50% maturity by sex and sexes combined for Gulf of Maine winter flounder in the Spring NEFSC, MADMF, and combined surveys.
NEFSC MADMF Both time period sex total N A50 total N A50 total N A50 81-01 male 948 2.5 1,406 3.3 2,354 2.9 female 1,601 2.6 2,533 3.4 4,134 3.1 Combined 2,489 2.6 3,766 3.3 6,255 3.0 Table B2.44. Comparison of length and age at 50% maturity for Gulf of Maine winter flounder in the spring NEFSC and MADMF surveys with the sexes combined. NEFSC data was limited to inshore Gulf of Maine Massachusetts strata (58-66) which overlap with the MADMF survey (25-36).
NEFSC MADMF time period total N L50 A50 total N L50 A50 81-85 209 24.0 2.4 479 29.1 3.5 86-90 248 21.0 2.1 763 28.5 3.4 91-95 493 25.0 2.8 1,312 28.4 3.2 96-01 577 23.0 2.5 1,212 27.7 3.3 81-01 1,527 23.5 2.5 3,766 28.3 3.3 274 36th SAW Consensus Summary
Table B2.45. Virtual Population Analysis for Gulf of Maine winter flounder, 1982-2001.
Fisheries Assessment Toolbox gom wf total catch Run Number 1 12/3/2002 12:55:40 PM FACT Version 1.5.0 gom wf total catch 1982 - 2002 Input Parameters and Options Selected Natural mortality is a matrix below Oldest age (not in the plus group) is 7 For all years prior to the terminal year ( 20 ), backcalculated stock sizes for the following ages used to estimate total mortality (Z) for age 7 : 5 6 7 This method for estimating F on the oldest age is generally used when a flat-topped partial recruitment curve is thought to be characteristic of the stock.
F for age 8 + is then calculated from the following ratios of F[age 8 +] to F[age 7 ]
1982 1 1983 1 1984 1 1985 1 1986 1 1987 1 1988 1 1989 1 1990 1 1991 1 1992 1 1993 1 1994 1 1995 1 1996 1 1997 1 1998 1 1999 1 2000 1 2001 1 Stock size of the 8 + group is then calculated using the following method: CATCH EQUATION Partial recruitment estimate for 2002 1 0.02 2 0.04 3 0.15 4 0.57 5 1 6 1 7 1 The Indices that will be used in this run are:
1 NEC_S11 2 NEC_S22 3 NEC_S33 4 NEC_S44 5 NEC_S55 6 NEC_S66 7 NEC_S77 8 NEC_S88 9 NEC_F23 10 NEC_F34 11 NEC_F45 12 NEC_F56 13 NEC_F67 14 MA_S11 15 MA_S22 16 MA_S33 17 MA_S44 18 MA_S55 19 MA_S66 20 MA_S77 21 MA_S88 22 MA_F01 23 MA_F12 24 MA_F23 25 MA_F34 26 MA_F45 27 SEA_S11 28 SEA_S22 29 SEA_S33 30 SEA_S44 31 SEA_S55 32 SEA_S66 33 SEA_S77 36th SAW Consensus Summary 275
Table B2.45. Continued.
STOCK NUMBERS (Jan 1) in thousands 1982 1983 1984 1985 1986 1987 1988 1 11761 8778 6269 9277 7686 6125 4482 2 14415 9522 7055 5100 7547 6218 4944 3 11100 9170 6945 4917 3886 5675 4590 4 6207 4316 5725 3788 2563 2334 2808 5 3058 1927 1869 2962 1180 1327 804 6 1177 1235 802 756 683 628 368 7 571 405 683 342 259 240 233 8 212 337 486 209 156 232 166 1+ 48500 35690 29834 27351 23959 22779 18395 1989 1990 1991 1992 1993 1994 1995 1 4043 4242 4542 3322 3240 4519 7503 2 3622 3259 3438 3680 2673 2611 3670 3 3589 2569 2337 2448 2618 1989 2049 4 2659 1599 1201 1013 1279 1488 1197 5 1232 779 371 373 273 461 641 6 331 291 177 94 117 91 228 7 77 74 85 40 16 36 34 8 56 44 60 26 05 13 22 1+ 15610 12857 12211 10996 10221 11208 15343 1996 1997 1998 1999 2000 2001 2002 1 7588 7249 8967 10080 7474 7391 6274 2 6104 6161 5902 7301 8237 6099 6033 3 2919 4840 4792 4742 5957 6714 4971 4 1345 1704 3415 3667 3819 4789 5444 5 302 728 925 2334 2832 2899 3624 6 83 172 470 454 1764 2132 2001 7 29 47 112 286 308 1388 1572 8 32 57 15 190 188 638 1558 1+ 18402 20958 24598 29055 30578 32050 31477 276 36th SAW Consensus Summary
Table B2.45. Continued.
FISHING MORTALITY 1982 1983 1984 1985 1986 1987 1988 1 0.01 0.02 0.01 0.01 0.01 0.01 0.01 2 0.25 0.12 0.16 0.07 0.09 0.10 0.12 3 0.74 0.27 0.41 0.45 0.31 0.50 0.35 4 0.97 0.64 0.46 0.97 0.46 0.87 0.62 5 0.71 0.68 0.71 1.27 0.43 1.08 0.69 6 0.87 0.39 0.65 0.87 0.85 0.79 1.36 7 0.76 0.56 0.70 1.22 0.57 1.01 0.88 8 0.76 0.56 0.70 1.22 0.57 1.01 0.88 1989 1990 1991 1992 1993 1994 1995 1 0.02 0.01 0.01 0.02 0.02 0.01 0.01 2 0.14 0.13 0.14 0.14 0.10 0.04 0.03 3 0.61 0.56 0.64 0.45 0.37 0.31 0.22 4 1.03 1.26 0.97 1.11 0.82 0.64 1.18 5 1.24 1.28 1.17 0.96 0.90 0.51 1.84 6 1.30 1.03 1.29 1.56 0.97 0.77 1.87 7 1.31 1.26 1.26 1.09 0.95 0.55 2.03 8 1.31 1.26 1.26 1.09 0.95 0.55 2.03 1996 1997 1998 1999 2000 2001 1 0.01 0.01 0.01 0.00 0.00 0.00 2 0.03 0.05 0.02 0.00 0.00 0.00 3 0.34 0.15 0.07 0.02 0.02 0.01 4 0.41 0.41 0.18 0.06 0.08 0.08 5 0.36 0.24 0.51 0.08 0.08 0.17 6 0.37 0.23 0.30 0.19 0.04 0.10 7 0.37 0.24 0.44 0.10 0.07 0.06 8 0.37 0.24 0.44 0.10 0.07 0.06 5,6 Average F for 5,6 1982 1983 1984 1985 1986 1987 1988 5,6 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1989 1990 1991 1992 1993 1994 1995 5,6 1.27 1.16 1.23 1.26 0.94 0.64 1.85 1996 1997 1998 1999 2000 2001 5,6 0.36 0.23 0.40 0.13 0.06 0.14 Biomass Weighted F 1982 1983 1984 1985 1986 1987 1988 0.60 0.33 0.42 0.70 0.30 0.55 0.40 1989 1990 1991 1992 1993 1994 1995 0.74 0.64 0.54 0.49 0.41 0.39 0.51 1996 1997 1998 1999 2000 2001 0.20 0.17 0.14 0.05 0.05 0.07 36th SAW Consensus Summary 277
Table B2.45. Continued.
BACKCALCULATED PARTIAL RECRUITMENT 1982 1983 1984 1985 1986 1987 1988 1 0.01 0.03 0.01 0.01 0.01 0.01 0.01 2 0.26 0.17 0.23 0.06 0.10 0.10 0.09 3 0.77 0.40 0.58 0.36 0.37 0.47 0.25 4 1.00 0.94 0.65 0.76 0.54 0.80 0.46 5 0.73 1.00 1.00 1.00 0.51 1.00 0.50 6 0.89 0.58 0.93 0.69 1.00 0.73 1.00 7 0.79 0.83 1.00 0.96 0.68 0.93 0.64 8 0.79 0.83 1.00 0.96 0.68 0.93 0.64 1989 1990 1991 1992 1993 1994 1995 1 0.01 0.01 0.01 0.01 0.02 0.01 0.00 2 0.11 0.10 0.11 0.09 0.10 0.06 0.01 3 0.46 0.44 0.49 0.29 0.38 0.40 0.11 4 0.78 0.98 0.75 0.71 0.84 0.83 0.58 5 0.95 1.00 0.91 0.62 0.93 0.66 0.91 6 0.99 0.81 1.00 1.00 1.00 1.00 0.92 7 1.00 0.98 0.98 0.70 0.98 0.72 1.00 8 1.00 0.98 0.98 0.70 0.98 0.72 1.00 1996 1997 1998 1999 2000 2001 1 0.02 0.01 0.01 0.01 0.04 0.02 2 0.08 0.13 0.04 0.02 0.05 0.03 3 0.82 0.36 0.13 0.09 0.22 0.06 4 1.00 1.00 0.35 0.31 0.90 0.46 5 0.87 0.58 1.00 0.42 1.00 1.00 6 0.88 0.56 0.58 1.00 0.47 0.61 7 0.88 0.58 0.86 0.51 0.80 0.37 8 0.88 0.58 0.86 0.51 0.80 0.37 MEAN BIOMASS (using catch mean weights at age) 1982 1983 1984 1985 1986 1987 1988 1 859 907 334 344 312 188 137 2 2586 2058 1522 755 1911 1287 1591 3 2693 2611 1588 1124 1242 1589 1489 4 1782 1468 1677 1000 958 757 932 5 1196 826 668 907 581 516 346 6 581 741 382 375 344 342 140 7 345 268 385 169 181 149 146 8 277 275 357 125 132 173 122 1+ 10319 9153 6914 4798 5662 5000 4903 1989 1990 1991 1992 1993 1994 1995 1 131 153 197 93 90 118 292 2 604 751 746 714 523 223 417 3 1014 716 680 729 760 591 577 4 873 452 399 304 364 484 280 5 407 256 123 141 109 211 151 6 170 130 67 35 47 46 63 7 47 39 34 24 11 29 13 8 41 29 31 22 05 10 11 1+ 3285 2527 2275 2062 1909 1710 1802 1996 1997 1998 1999 2000 2001 1 199 282 292 320 264 221 2 1520 1041 901 581 805 496 3 986 1696 1615 1667 1847 1920 4 523 656 1338 1584 1569 1898 5 137 371 393 1138 1354 1313 6 49 112 278 268 1060 1259 7 19 31 82 225 235 1026 8 34 40 21 175 196 592 1+ 3466 4228 4918 5957 7328 8724 00 278 36th SAW Consensus Summary
Table B2.45. Continued.
SSB AT THE START OF THE SPAWNING SEASON -MALES AND FEMALES (MT) (using SSB mean weights) 1982 1983 1984 1985 1986 1987 1988 1 00 00 00 00 00 00 00 2 00 00 00 00 00 00 00 3 454 368 265 189 144 257 204 4 1685 1307 1578 898 744 714 857 5 1255 867 778 991 549 571 376 6 665 733 437 383 362 370 180 7 390 292 449 194 193 165 167 8 339 325 433 164 157 220 153 1+ 4790 3890 3941 2820 2149 2298 1936 1989 1990 1991 1992 1993 1994 1995 1 00 00 00 00 00 00 00 2 00 00 00 00 00 00 00 3 185 95 103 107 107 82 54 4 824 450 365 302 366 444 295 5 474 323 151 167 124 208 198 6 183 149 82 42 58 51 87 7 50 51 46 25 12 26 17 8 54 38 40 28 06 11 15 1+ 1769 1106 787 672 672 823 666 1996 1997 1998 1999 2000 2001 1 00 00 00 00 00 00 2 00 00 00 00 00 00 3 96 241 194 185 157 189 4 421 596 1180 1283 1315 1521 5 133 373 428 1116 1369 1335 6 47 107 285 268 1022 1211 7 19 33 85 219 227 980 8 39 44 24 188 208 630 1+ 754 1395 2197 3260 4298 5866 36th SAW Consensus Summary 279
Table B2.45b. VPA retrospective analysis for Gulf of Maine winter flounder.
Fishing Mortality Terminal year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1995 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.26 1.14 1.17 1.05 0.59 0.29 0.72 1996 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.15 1.22 1.21 0.85 0.52 1.05 0.07 1997 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.15 1.22 1.22 0.87 0.55 1.19 0.14 0.09 1998 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.16 1.22 1.23 0.88 0.56 1.27 0.16 0.09 0.23 1999 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.16 1.23 1.25 0.91 0.6 1.54 0.23 0.13 0.21 0.09 2000 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.16 1.23 1.25 0.93 0.63 1.73 0.30 0.19 0.27 0.08 0.06 2001 0.79 0.53 0.68 1.07 0.64 0.94 1.02 1.27 1.16 1.23 1.26 0.94 0.64 1.85 0.36 0.23 0.40 0.13 0.06 0.14 Spawning Stock Biomass Terminal year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1995 4790 3890 3941 2821 2150 2299 1939 1776 1121 831 804 910 1283 1759 1996 4790 3890 3941 2820 2149 2298 1937 1770 1108 795 695 735 1080 1373 2108 1997 4790 3890 3941 2820 2149 2298 1937 1770 1108 794 690 722 957 1046 1510 2530 1998 4790 3890 3941 2820 2149 2298 1936 1770 1108 793 688 715 934 1008 1417 2274 2956 1999 4790 3890 3941 2820 2149 2298 1936 1769 1106 789 678 688 868 799 1137 2082 2799 4038 2000 4790 3890 3941 2820 2149 2298 1936 1769 1106 788 674 678 839 719 873 1753 2616 3601 4808 2001 4790 3890 3941 2820 2149 2298 1936 1769 1106 787 672 672 823 666 754 1395 2197 3260 4298 5866 Population Numbers Age1:
Terminal year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 1995 11762 8779 6271 9285 7698 6150 4556 4377 4717 5296 6200 6700 6302 8273 6222 1996 11761 8778 6269 9278 7688 6129 4496 4096 4336 5330 5327 6547 6324 7084 6987 6895 1997 11761 8778 6269 9278 7688 6127 4499 4067 4390 4811 4419 4909 6072 7098 7490 7043 7090 1998 11761 8778 6269 9278 7688 6127 4497 4061 4380 4723 4402 4662 5446 6768 7060 7347 8617 11412 1999 11761 8778 6269 9277 7687 6126 4487 4052 4283 4657 3598 4474 5794 7011 7774 7883 9687 13335 16197 2000 11761 8778 6269 9277 7686 6125 4484 4045 4262 4567 3482 3425 5692 7749 7257 7352 9106 10817 8113 6990 2001 11761 8778 6269 9277 7686 6125 4482 4043 4242 4542 3322 3240 4519 7503 7588 7249 8967 10080 7474 7391 6274 280 36th SAW Consensus Summary
Table B2.46. VPA Bootstrap results: precision of estimates.
The number of bootstraps: 500 Bootstrap Output Variable: N hat NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN N 1 6274 6578 2984 0.48 N 2 6033 6313 1951 0.32 N 3 4971 5148 1277 0.26 N 4 5444 5544 1043 0.19 N 5 3624 3711 674 0.19 N 6 2001 2043 394 0.20 N 7 1572 1576 273 0.17 N 8 1068 1077 170 0.16 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI N 1 304 133 4.85 5969 0.499901 3546 11460 N 2 280 87 4.65 5752 0.339112 3677 8478 N 3 177 57 3.56 4794 0.266440 3559 6826 N 4 100 47 1.83 5344 0.195187 4245 6919 N 5 88 30 2.42 3536 0.190486 2818 4483 N 6 42 18 2.11 1959 0.201157 1523 2548 N 7 04 12 0.27 1568 0.173815 1286 1984 N 8 10 08 0.90 1058 0.160299 874 1312 Bootstrap Output Variable: F t NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN Age 1 0.0030 0.0032 0.0011 0.37 Age 2 0.0044 0.0045 0.0011 0.25 Age 3 0.0096 0.0097 0.0018 0.19 Age 4 0.0790 0.0795 0.0139 0.18 Age 5 0.1708 0.1730 0.0311 0.18 Age 6 0.1048 0.1074 0.0180 0.17 Age 7 0.0624 0.0633 0.0098 0.16 Age 8 0.0624 0.0633 0.0098 0.16 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI Age 1 0.0001690 0.0000491 5.641 0.0028262 0.39 0.0021 0.0048 Age 2 0.0001079 0.0000490 2.477 0.0042508 0.26 0.0032 0.0061 Age 3 0.0001559 0.0000812 1.625 0.0094377 0.19 0.0075 0.0122 Age 4 0.0005479 0.0006197 0.694 0.0784051 0.18 0.0640 0.0998 Age 5 0.0021128 0.0013886 1.237 0.1687286 0.18 0.1359 0.2178 Age 6 0.0025929 0.0008055 2.474 0.1022216 0.18 0.0836 0.1266 Age 7 0.0009146 0.0004373 1.465 0.0614994 0.16 0.0506 0.0752 Age 8 0.0009146 0.0004373 1.465 0.0614994 0.16 0.0506 0.0752 Bootstrap Output Variable: Mean Biomass NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN 8723.9106 8873.3264 775.7433 0.09 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI 149.4158 34.6923 1.71 8574.4947 0.09 7730.5482 9603.4137 Bootstrap Output Variable: SSB spawn t NLLS BOOTSTRAP BOOTSTRAP C.V. FOR ESTIMATE MEAN StdError NLLS SOLN 5865.7415 5945.3298 554.7207 0.09 NLLS EST C.V. FOR BIAS BIAS PERCENT CORRECTED CORRECTED LOWER UPPER ESTIMATE STD ERROR BIAS FOR BIAS ESTIMATE 80%CI 80%CI 79.59 24.81 1.36 5786.15 0.10 5203.0726 6580.6435 36th SAW Consensus Summary 281
Table B2.47. Yield Per Recruit analysis for Gulf of Maine winter flounder.
The NEFC Yield and Stock Size per Recruit Program - PDBYPRC PC Ver.2.0 [Method of Thompson and Bell (1934)] 1-Jan-1999 Run Date: 3-10-2002; Time: 12:05:35.00 gulf of Maine Winter Flounder - 1999-01 PR, Mean Weights at Age from Proportion of F before spawning: 0.2500 Proportion of M before spawning: 0.2500 Natural Mortality is Constant at: 0.200 Initial age is: 1; Last age is: 15 Last age is a TRUE Age; Original age-specific PRs, Mats, and Mean Wts from file:
==> C:\Program Files\FACT\wv\ypr\gomwfy3.dat Age-specific Input data for Yield per Recruit Analysis Age l Fish Mort Nat Mort l Proportion l Average Weights l Pattern Pattern l Mature l Catch Stock 1 l 0.0300 1.0000 l 0.0000 l 0.036 0.021 2 l 0.0400 1.0000 l 0.0000 l 0.095 0.059 3 l 0.1300 1.0000 l 0.1600 l 0.351 0.206 4 l 0.5700 1.0000 l 0.8600 l 0.471 0.420 5 l 1.0000 1.0000 l 1.0000 l 0.550 0.512 6 l 1.0000 1.0000 l 1.0000 l 0.691 0.626 7 l 1.0000 1.0000 l 1.0000 l 0.872 0.788 8 l 1.0000 1.0000 l 1.0000 l 0.993 0.993 9 l 1.0000 1.0000 l 1.0000 l 1.091 1.091 10 l 1.0000 1.0000 l 1.0000 l 1.171 1.171 11 l 1.0000 1.0000 l 1.0000 l 1.234 1.234 12 l 1.0000 1.0000 l 1.0000 l 1.284 1.284 13 l 1.0000 1.0000 l 1.0000 l 1.323 1.323 14 l 1.0000 1.0000 l 1.0000 l 1.353 1.353 15 l 1.0000 1.0000 l 1.0000 l 1.377 1.377 Summary of Yield per Recruit Analysis:
Slope of the Yield/Recruit Curve at F=0.00: --> 2.0105 F level at slope=1/10 of the above slope (F0.1): -----> 0.258 Yield/Recruit corresponding to F0.1: -----> 0.1970 F level to produce Maximum Yield/Recruit (Fmax): -----> 0.687 Yield/Recruit corresponding to Fmax: -----> 0.2201 F level at 40 % of Max Spawning Potential (F40): -----> 0.261 SSB/Recruit corresponding to F40: --------> 0.8333 1
Listing of Yield per Recruit Results for:
FMORT TOTCTHN TOTCTHW TOTSTKN TOTSTKW SPNSTKN SPNSTKW % MSP 0.00 0.00000 0.00000 5.2420 2.4078 2.6476 2.0834 100.00 0.10 0.17406 0.12996 4.5658 1.6980 1.9691 1.3773 66.11 0.20 0.26851 0.18214 4.1562 1.3009 1.5634 0.9877 47.41 F0.1 0.26 0.30487 0.19700 3.9894 1.1500 1.4000 0.8411 40.37 F40% 0.26 0.30682 0.19770 3.9802 1.1419 1.3911 0.8333 40.00 0.30 0.32662 0.20421 3.8874 1.0616 1.3007 0.7557 36.27 0.40 0.36623 0.21387 3.6983 0.9070 1.1185 0.6074 29.16 0.50 0.39537 0.21807 3.5575 0.8010 0.9848 0.5067 24.32 0.60 0.41803 0.21972 3.4476 0.7243 0.8823 0.4345 20.85 Fmax 0.69 0.43413 0.22009 3.3697 0.6733 0.8108 0.3869 18.57 0.70 0.43638 0.22010 3.3588 0.6664 0.8009 0.3805 18.26 0.80 0.45170 0.21982 3.2847 0.6211 0.7343 0.3387 16.26 0.90 0.46481 0.21920 3.2215 0.5846 0.6787 0.3053 14.66 1.00 0.47624 0.21839 3.1666 0.5544 0.6314 0.2781 13.35 1.10 0.48637 0.21747 3.1180 0.5288 0.5905 0.2553 12.25 1.20 0.49545 0.21650 3.0745 0.5069 0.5547 0.2359 11.32 1.30 0.50368 0.21549 3.0352 0.4878 0.5230 0.2193 10.52 1.40 0.51121 0.21446 2.9992 0.4708 0.4947 0.2047 9.83 1.50 0.51816 0.21343 2.9660 0.4557 0.4693 0.1919 9.21 1.60 0.52462 0.21238 2.9352 0.4421 0.4463 0.1805 8.67 1.70 0.53064 0.21134 2.9065 0.4297 0.4253 0.1703 8.18 1.80 0.53630 0.21029 2.8795 0.4183 0.4060 0.1611 7.73 1.90 0.54163 0.20924 2.8541 0.4078 0.3883 0.1527 7.33 2.00 0.54668 0.20819 2.8300 0.3981 0.3719 0.1451 6.96 282 36th SAW Consensus Summary
Table B2.48. Stock-recruitment model comparison for Gulf of Maine winter flounder.
Prior Prior Prior Prior Prior Prior Prior Prior Prior Prior 1 0 1 0 1 0 0 0 0 0 BH ABH PBH PABH PRBH PRABH RK ARK PRK PARK Posterior Probability 0.36 0.00 0.32 0.00 0.31 0.00 0.00 0.00 0.00 0.00 Odds Ratio for Most Likely Model 1.00 1.12 1.16 Normalized Likelihood 0.363 0.000 0.323 0.000 0.313 0.000 0.000 0.000 0.000 0.000 Model AIC Ratio 1.160 0 1.033 0 1.000 0 0 0 0 0 BH ABH PBH PABH PRBH PRABH RK ARK PRK PARK Number_of_data_points 20 20 20 20 20 20 20 20 20 20 Number_of_parameters 3 4 3 4 3 4 3 4 3 4 Fit_negloglikelihood 41.146 33.566 41.263 33.724 41.295 33.732 43.534 34.926 52.285 37.530 Penalty_steepness 0 0 -0.810 -1.087 0 0 0 0 0 0 Penalty_slope 0 0 0 0 0 0 0 0 3.160 -0.774 Penalty_unfished_R 0 0 0 0 2.085 1.809 0 0 0 0 Negative_loglikelihood 41.146 33.566 40.452 32.637 43.380 35.541 43.534 34.926 55.445 36.756 Bias-corrected_AIC 89.792 77.799 90.025 78.115 90.090 78.130 94.568 80.519 112.070 85.726 Most likely Power Power Power Fmsy>> Fmsy>> no stock Power parametric spectrum spectrum spectrum Fmax Fmax recruit data spectrum model dominant dominant dominant at SSB dominant frequency frequency frequency where frequency exceeds exceeds exceeds density exceeds Diagnostic Comments 1/2 time 1/2 time 1/2 time dependence 1/2 time series series series is predicted series length length length length 36th SAW Consensus Summary 283
Table B2.48. Continued.
Parameter Point_Estimate BH ABH PBH PABH PRBH PRABH RK ARK PRK PARK MSY 1.543 1.587 1.596 1.623 1.640 1.771 1.753 1.836 2.153 0.568 FMSY 0.430 0.415 0.405 0.380 0.410 0.395 0.745 0.705 0.375 0.240 SMSY 4.104 4.359 4.484 4.830 4.554 5.087 2.871 3.154 6.485 2.594 Alpha 7.706 8.051 8.167 8.579 8.365 9.161 2.043 1.982 1.296 0.828 expected_alpha 8.084 8.422 8.574 8.998 8.783 9.612 2.171 2.097 1.500 1.431 Beta 0.387 0.473 0.516 0.698 0.516 0.636 -0.359 -0.323 -0.134 -0.281 Steepness 0.923 0.911 0.905 0.881 0.907 0.896 R_at_input_SMAX 7.302 7.542 7.606 7.800 7.791 8.398 4.388 5.310 10.032 2.233 expected_R_at_input_SMAX 7.661 7.889 7.985 8.182 8.180 8.811 4.663 5.618 11.611 3.862 unfished_S 18.138 18.883 19.118 19.925 19.594 21.389 8.144 8.863 16.247 6.058 unfished_R 7.544 7.855 7.952 8.288 8.150 8.897 3.387 3.686 6.758 2.520 Sigma 0.310 0.300 0.312 0.309 0.312 0.310 0.349 0.336 0.541 1.047 Phi 0.720 0.734 0.736 0.749 0.973 Sigmaw 0.208 0.210 0.210 0.222 0.240 last_residual_R -1.177 -1.392 -1.991 -0.141 3.699 last_logresidual_R -0.172 -0.200 -0.276 -0.022 0.890 expected_lognormal_error_term 1.049 1.046 1.050 1.049 1.050 1.049 1.063 1.058 1.157 1.729 prior_mean_steepness 0.80 0.80 prior_se_steepness 0.09 0.09 prior_mean_slope 0.79 0.79 prior_se_slope 0.18 0.18 prior_mean_unfished_R 10.09 10.09 prior_se_unfished_R 2.06 2.06 284 36th SAW Consensus Summary
Table B2.49. Input parameters and stochastic projection results for Gulf of Maine winter flounder using recruitment predicted from the Beverton-Holt stock-recruitment model and an estimated Fmsy = 0.43.
Stock Size Mean on 1 Jan Fishing Weights Mean Mean 2002 Mortality Proportion Proportion Spawning Weights Weights Age (000s) Pattern Landed mature Stock Landings Discards 1 6274 0.030 0.000 0.000 0.021 0.000 0.036 2 6033 0.040 0.040 0.000 0.059 0.000 0.089 3 4971 0.130 0.710 0.160 0.203 0.399 0.229 4 5444 0.570 0.940 0.860 0.419 0.480 0.306 5 3624 1.000 0.980 1.000 0.512 0.553 0.389 6 2001 1.000 0.980 1.000 0.626 0.696 0.468 7 1572 1.000 0.990 1.000 0.788 0.875 0.694 8+ 1558 1.000 0.990 1.000 1.100 1.105 0.867 F2002 is assumed equal to F2001; F during 2003-2013 = Fmsy = 0.43.
Forecast Medians (50% probability level) 2002 2003 2013 000s Metric tons F Land Disc SSB F Land Disc SSB F Land Disc SSB 0.14 0.9 <0.1 7.6 Fmsy=0.43 2.9 0.1 7.8 Fmsy=0.43 1.5 0.1 4.3 F2002 is assumed 0.85*F2001 (15% decrease in F from 2001 to 2002); F during 2003-2013 = Fmsy = 0.43.
Forecast Medians (50% probability level) 2002 2003 2013 000s Metric tons F Land Disc SSB F Land Disc SSB F Land Disc SSB 0.12 0.8 <0.1 7.7 Fmsy=0.43 2.9 0.1 7.9 Fmsy=0.43 1.6 0.1 4.3 36th SAW Consensus Summary 285
Figure B2.1. Statistical areas for reporting landings in the northwest Atlantic ocean.
286 36th SAW Consensus Summary
3000 2500 otter trawl gillnet shrimp Landing (mt) 2000 other 1500 1000 500 0
1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.2. Gulf of Maine winter flounder commercial landings by gear from 1964-2001.
36th SAW Consensus Summary 287
3000 2500 ME NH MA Landing (mt) 2000 RI 1500 1000 500 0
1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.3. Gulf of Maine winter flounder commercial landings by state from 1964-2001.
3000 s511 2500 s512 s513 Landing (mt) s514 2000 s515 1500 1000 500 0
1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.4. Gulf of Maine winter flounder commercial landings by statistical area from 1964-2001.
288 36th SAW Consensus Summary
3000 2500 qtr 1 qtr 2 Landing (mt) 2000 qtr 3 qtr 4 1500 1000 500 0
1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.5. Gulf of Maine winter flounder commercial landings by quarter from 1964-2001.
3000 2500 unclassified small Landing (mt) medium 2000 large 1500 1000 500 0
1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.6. Gulf of Maine winter flounder commercial landings by market category from 1964-2001.
36th SAW Consensus Summary 289
Gulf of Maine Winter Flounder Recreational landings and b2 Catch 2500 7000 Recreational landing (000s) 6000 2000 Number (000s) metric tons Recreational Landings mt 5000 1500 4000 1000 3000 B2s Catch (000s) 2000 500 1000 0 0 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year Figure B2.7. Recreational landings in numbers and metric tons for Gulf of Maine winter flounder. B2 catch in numbers is also shown.
290 36th SAW Consensus Summary
Gulf of Maine winter flounder estimated culling ogives 0.18 1.0 0.16 1989-1993 Observer data used for 1982-1993 0.8 0.14 0.12 0.6 0.10 0.08 Length Proportion from Observer data 0.4 0.06 Kept n = 334 0.04 Discards 0.2 Proportion Discarded 0.02 n = 155 0.00 0.0 20 25 30 35 40 45 50 length (cm) 1.0 0.20 1995-2000 observer data used for 1994-2001 0.8 0.15 0.6 0.10 0.4 Discards 0.05 n = 143 0.2 Kept n = 2,413 0.00 0.0 20 25 30 35 40 45 50 length (cm)
Figure B2.8. Gulf of Maine winter flounder estimated culling ogive from Observer data for estimating trawl discards in the survey method.
36th SAW Consensus Summary 291
Culling ogive estimated from sea sampling data 1.0 0.9 0.8 Proportion Discarded 0.7 1995-2000 0.6 1989-1993 0.5 0.4 0.3 1994 minimum size 0.2 0.1 0.0 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 length (cm)
Figure B2.9. Gulf of Maine winter flounder estimated culling ogive. Observer data from 1989-1993 was used to estimate an ogive used for years 1982-1993. Observer data from 1995-2000 was used to estimate an ogive used for years 1994-2001.
292 36th SAW Consensus Summary
Gulf of Maine winter flounder mean weights at age 2.0 Catch mean weight 1.5 age 8+
1.0 age 7 age 6 age 5 0.5 age 4 age 3 age 2 age 1 0.0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year Figure B2.10. Gulf of Maine winter flounder VPA mean weights at age.
36th SAW Consensus Summary 293
5 1.5 4 1982 1989 1.0 3
2 0.5 1
1.5 2.0 1983 1990 1.5 1.0 1.0 0.5 0.5 1.5 2.0 1984 1991 1.5 1.0 1.0 0.5 0.5 1.0 2.0 Numbers of fish (000's) Numbers of fish (000's) 0.8 1.5 1985 1992 0.6 1.0 0.4 0.5 0.2 1.0 2.0 0.8 1993 1.5 1986 0.6 1.0 0.4 0.5 0.2 1.0 2.0 0.8 1994 1.5 1987 0.6 1.0 0.4 0.5 0.2 1.0 2.0 0.8 1.5 1988 1995 0.6 1.0 0.4 0.5 0.2 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Age Commercial Landings Age Recreational Landings Recreational Discards Large Mesh Trawl Discards Shrimp Fishery Discards Gillnet Discards Figure B2.11. Gulf of Maine winter flounder catch at age composition in numbers from 1982-2001.
294 36th SAW Consensus Summary
0.8 0.6 1996 0.4 0.2 0.6 1997 0.4 0.2 0.6 1998 Numbers of fish (000's) 0.4 0.2 0.4 0.3 1999 0.2 0.1 0.4 0.3 2000 0.2 0.1 0.4 2001 0.3 0.2 0.1 1 2 3 4 5 6 7 8 Age Commercial Landings Recreational Landings Recreational Discards Large Mesh Trawl Discards Shrimp Fishery Discards Gillnet Discards Figure B2.11. Continued.
36th SAW Consensus Summary 295
Gulf of Maine Winter Flounder numbers of fish in the catch at age 14 commercial landings numbers of fish (000's) 12 recreational landings recreational discards 10 large mesh trawl discards shrimp discards 8 gillnet discards 6
4 2
0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year Figure B2.12. Gulf of Maine winter flounder catch composition in numbers 296 36th SAW Consensus Summary
Age 0 1 2 3 4 5 6 7 8 1980 1985 Year 1990 1995 2000 Figure B2.13. Total Gulf of Maine winter flounder catch at age.
36th SAW Consensus Summary 297
Figure B2.14. Distribution of winter flounder during the NEFSC spring bottom trawl surveys from 1995-1999.
298 36th SAW Consensus Summary
Figure B2.15. Distribution of winter flounder during the NEFSC fall bottom trawl surveys from 1995-1999.
36th SAW Consensus Summary 299
NEFSC Spring Offshore Strata 26 27 15 38 39 40 10 5
Weight per tow (kg)
NEFSC Spring Inshore Boston and North Strata 80 65 60 66 40 20 NEFSC Spring Inshore Cape Cod Bay Strata 80 58 59 60 60 61 40 20 0
1970 1975 1980 1985 1990 1995 2000 year Figure B2.16. NEFCS spring Gulf of Maine winter flounder weight per tow trends among strata.
300 36th SAW Consensus Summary
20 NEFSC Fall Offshore Strata 26 27 15 38 39 40 10 5
NEFSC Fall Inshore Boston and North Strata Weight per tow (kg) 120 100 65 66 80 60 40 20 NEFSC Fall Inshore Cape Cod Bay Strata 120 100 58 59 80 60 61 60 40 20 0
1970 1980 1990 2000 year Figure B2.17. NEFCS fall Gulf of Maine winter flounder weight per tow trends among strata.
36th SAW Consensus Summary 301
NEFSC Spring 16 14 Inshore & Offshore Number / tow Inshore & Offshore Strata 14 12 Offshore Number / tow 10 12 8
10 6
8 Offshore Strata 4 6 2 4 0
-2 2
-4 0
1970 1975 1980 1985 1990 1995 2000 8 6 Inshore & Offshore kg / tow Inshore & Offshore Strata 6 4 Offshore kg / tow 4 2 Offshore Strata 2 0 0 -2 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.18. NEFSC spring offshore and inshore/offshore survey stratified mean number and mean weight (kg) per tow for Gulf of Maine winter flounder. Trawl door conversion factors are use where appropriate.
302 36th SAW Consensus Summary
NEFSC Fall 16 16 Inshore & Offshore Number / tow 14 14 Inshore & Offshore Strata 12 Offshore Number / tow 12 10 10 8 6
8 Offshore Strata 4
6 2
4 0 2 -2
-4 0
1965 1970 1975 1980 1985 1990 1995 2000 8
6 Inshore & Offshore kg / tow Inshore & Offshore Strata 6
Offshore kg / tow 4
Offshore Strata 4
2 2
0 0 -2 1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.19. NEFSC Fall offshore and inshore/offshore survey stratified mean numbers and mean weight (kg) per tow for Gulf of Maine winter flounder. Trawl door conversion factors are use where appropriate. Data for 2002 is preliminary.
36th SAW Consensus Summary 303
MADMF Spring 180 160 140 numbers / tow 120 100 80 60 40 20 0
1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 40 35 30 kg / tow 25 20 15 10 5
1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year Figure B2.20. Massachusetts Division of Marine Fisheries (MADMF) spring survey stratified mean numbers and mean weight (kg) per tow for Gulf of Maine winter flounder.
304 36th SAW Consensus Summary
MADMF Fall 140 120 numbers / tow 100 80 60 40 20 0
1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 35 30 25 kg / tow 20 15 10 5
0 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year Figure B2.21. Massachusetts Division of Marine Fisheries (MDMF) fall survey stratified mean numbers and mean weight (kg) per tow for Gulf of Maine winter flounder.
36th SAW Consensus Summary 305
Seabrook Spring and Fall Indices 16 14 12 Fall Numbers/tow 10 8
6 4
2 Spring 0
1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year Figure B2.22. Seabrook Nuclear Power Plant in New Hampshire spring and fall survey mean numbers per tow for Gulf of Maine winter flounder. No length data exists from 1975 to 1984 and 1993.
306 36th SAW Consensus Summary
Gulf of Maine Winter flounder 1.0 0.8 NEFSC proportion mature MADMF 0.6 0.4 0.2 0.0 0 5 10 15 20 25 30 35 40 45 50 Length (cm)
Figure B2.23. Comparison of Gulf of Maine winter flounder maturity ogives (sexes combined) estimated from the MADMF spring survey (strata 25-36) and the spring NEFSC survey data limited in inshore MA strata 58-66.
36th SAW Consensus Summary 307
Gulf of Maine Winter Flounder Total Catch and Fishing Mortality 5
Total Catch F (age 5-6) 2.0 4
F (age 5-6) 1.5
'000 mt 3
1.0 2 Commercial Landings 1 0.5 0 0.0 1965 1970 1975 1980 1985 1990 1995 2000 Year Figure B2.24. Total catch (landings and discards, '000 mt), commercial landings ('000 mt),
and fishing mortality rate (F, ages 5-6, unweighted) for Gulf of Maine winter flounder.
308 36th SAW Consensus Summary
Gulf of Maine Winter Flounder Precision of 2001 Estimates for SSB and F 100 90 10 Cumulative Probability Percent Frequency 80 70 60 50 5
40 30 20 10 0 0 0 2 4 6 8 10 Spawning Stock Biomass ('000 mt) 100 30 Cumulative Probability 90 Percent Frequency 80 25 70 60 20 50 15 40 30 10 20 5
10 0 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Fishing Mortality Rate Figure B2.25. Precision of estimates of spawning stock biomass ('000 mt) and fishing mortality rate (F, ages 5-6, unweighted) in 2001 for Gulf of Maine winter flounder.
Vertical bars display the range of the bootstrap estimates and the probability of individual values in the range. The solid curve gives the probability of SSB that is less or fishing mortality that is greater than any value along the X axis.
36th SAW Consensus Summary 309
Gulf of Maine Winter Flounder SSB and Recruitment 7 14 Recruitment (age 1, millions) 6 12 SSB 5 Recruitment 10 SSB ('000 mt) 4 8 3 6 2 4 1 2 0 0 1980 1985 1990 1995 2000 Recruitment Year Class, Biomass Year Figure B2.26. Spawning stock biomass (SSB, '000 mt) and recruitment (millions of fish at age-1) for Gulf of Maine winter flounder.
310 36th SAW Consensus Summary
Gulf of Maine winter flounder retrospective VPAs 1.5 F (ages 5-6) 1.0 0.5 0.0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 5000 SSB (000s mt) 4000 3000 2000 1000 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Age-1 recruits (millions) 18000 16000 14000 12000 10000 8000 6000 4000 2000 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Figure B2.27. Retrospective VPAs for Gulf of Maine winter flounder.
36th SAW Consensus Summary 311
Gulf of Maine winter flounder yield & spawning stock biomass per recruit 0.25 2.0 Yield per recruit (kg) SSB per Recruit (kg) 0.20 1.5 0.15 1.0 0.10 0.05 F40% 0.5 F0.1 FMSY FMax 0.00 0.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Fishing Mortality Rate Figure B2.28. Yield and spawning stock biomass per recruit estimates for Gulf of Maine winter flounder.
312 36th SAW Consensus Summary
Gulf of Maine Winter Flounder Beverton-Holt Model SSB - RECRUIT DATA FOR 1982-2001 YEAR CLASSES 14 12 Millions of Age-1 Fish 10 98 84 97 82 8 95 85 96 99 00 94 01 6 86 83 89 87 93 90 4 88 91 92 2
Figure B2.29. Beverton-Holt stock-recruitment model for Gulf of Maine winter flounder.
36th SAW Consensus Summary 313
8.0 F2002 = 0.85*F2001 = 0.12 7.5 Fmsy = 0.43 7.0 SSB ('000 mt) 6.5 6.0 5.5 5.0 4.5 Bmsy = 4,100 mt 4.0 3.5 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Year Figure B2.30. Median (50% probability) of forecast spawning stock biomass (SSB, mt) for Gulf of Maine winter flounder assuming F2002 = 0.85*F2001 = 0.12 and Fmsy fishing mortality rates during 2003-2013.
314 36th SAW Consensus Summary
Gulf of Maine Winter Flounder 2.0 95 1.5 BMSY F (ages 5-6) 92 91 89 90 88 85 1.0 93 87 82 84 94 86 0.5 83 FMSY 96 98 97 02 99 01 00 0.0 0 1 2 3 4 5 6 7 8 SSB (mt)
Figure B2.31. SSB and F (ages 5-6) for Gulf of Maine winter flounder. Biological reference points calculated from the Beverton-Holt model are also shown.
36th SAW Consensus Summary 315
C. GULF OF MAINE NORTHERN SHRIMP Terms of Reference
- 1. Characterize the commercial and recreational catch including landings and discards.
- 2. Estimate fishing mortality, spawning stock biomass, and total stock biomass for the current year and characterize the uncertainty of those estimates.
- 3. Evaluate methodologies for the development of biological reference points for Northern Shrimp.
Introduction 1.0 Management The Gulf of Maine fishery for northern shrimp (Pandalus borealis) is managed through interstate agreement among the states of Maine, New Hampshire and Massachusetts. The management unit is defined as the northern shrimp resource throughout the range of the species within U.S. waters of the northwest Atlantic Ocean from the shoreline to the seaward boundary of the EEZ. It is also recognized that the northern shrimp fishery, as defined here, is interstate and state-federal in nature, and that effective assessment and management can be enhanced through cooperative efforts with state and federal scientists and fishery managers. The management framework evolved from 1972 to 1979 under the auspices of the State/Federal Fisheries Management Program. In 1980, this program was restructured in the Northeast Region as the Interstate Fisheries Management Program of the ASMFC (McInnes 1986). Within the interstate structure, the Northern Shrimp Technical Committee (NSTC) provides annual stock assessments and related information to the ASMFC Northern Shrimp Section, which is the management body that establishes the annual fishing regulations. The management tools currently available to the Section include season length (within a time frame of December 1 through May 31) and gear restrictions.
1.1 Assessment Stock assessments initially consisted of total landings estimates, indices of abundance from Northeast Fishery Science Center (NEFSC) groundfish surveys, fishing mortality estimates from the application of cohort slicing of length frequencies from the State of Maine survey, and yield per recruit modeling (Clark and Anthony 1980; Clark 1981, 1982). The NSTC unified individual state port sampling programs in the early 1980s to better characterize catch at length and developmental stage (sex and maturity), and established a dedicated research trawl survey for the species in the summer of 1983 to monitor relative abundance, biomass, size structure and demographics of the stock. Subsequent stock assessments provided more detailed description of landings, size composition of catch, patterns in fishing effort, catch per unit effort, relative year 316 36th SAW Consensus Summary
class strength and survey indices of total abundance and biomass. Length distributions from the summer shrimp survey have been used for size composition analysis to estimate mortality rates, but did not fit the length-based models well because of variable recruitment and growth (Terceiro and Idoine 1990, Fournier et al. 1991).
Beginning in 1997, the northern shrimp stock in the Gulf of Maine has been evaluated more quantitatively using three analytical models that incorporate much of the available data:
- 1. Collie-Sissenwine analysis that tracks removals of shrimp using summer survey indices of recruits and fully-recruited shrimp scaled to total catch in numbers (from dealers reports and port sampling);
- 2. A surplus production analysis that models the biomass dynamics of the stock with a longer times series of total landings and three survey indices of stock abundance;
- 3. A yield-per-recruit (YPR) model and an eggs-per-recruit (EPR) model that simulate the life history of northern shrimp (including growth rates, transition rates, natural mortality, and fecundity) and fishing mortality on recruited shrimp. It uses estimates of trawl selectivity to estimate yield and egg production at various levels of fishing mortality, providing guidance on what levels of fishing are most productive and sustainable.
2.0 Life History Northern shrimp (Pandalus borealis) are protandric (sequential) hermaphrodites, maturing first as males at roughly 21/2 years of age and then transforming to females at roughly 31/2 years of age.
In the Gulf of Maine, spawning takes place in offshore waters beginning in late July. By early fall, most adult females extrude their eggs onto the abdomen. Egg bearing females move inshore in late autumn and winter, where the eggs hatch. Juveniles remain in coastal waters for a year or more before migrating to deeper offshore waters, where they mature as males. The exact extent and location of these migrations is variable and unpredictable. The males pass through a series of transitional stages before maturing as females. Some females may survive to repeat the spawning process in succeeding years. The females are the individuals targeted in the Gulf of Maine fishery. Natural mortality seems to be most pronounced immediately following hatching, and it is believed that most shrimp do not live past age 5.
Several year classes in the last decade have shown some percentage of 21/2 year old shrimp maturing as females instead of males. This presents both sexes in the same year class and may be a reaction to stress in the population as predicted by sex allocation theory (Charnov et al, 1978), or may be temperature or density driven (Apollonio et al, 1984, Koeller et al, 2000). In the 2001 year class, there is some evidence of early-maturing females appearing at 11/2 years (Figure 12), which is unprecedented in the Gulf of Maine.
36th SAW Consensus Summary 317
3.0 Fishery Description Northern shrimp occur in boreal and sub-arctic waters throughout the North Atlantic and North Pacific, where they support important commercial fisheries. In the western North Atlantic, commercial concentrations occur off Greenland, Labrador, and Newfoundland, in the Gulf of St.
Lawrence, and on the Scotian Shelf. The Gulf of Maine marks the southernmost extent of its Atlantic range. In the Gulf of Maine, primary concentrations occur in the western Gulf where bottom temperatures are coldest. In summer, adults are most common at depths of 90-180 meters.
The fishery has been seasonal in nature, peaking in late winter when egg-bearing females move into inshore waters and terminating in spring under regulatory closure. Northern shrimp has been an accessible and important resource to fishermen working inshore areas in smaller vessels who otherwise have few options due to seasonal changes in availability of groundfish, lobsters and other species.
The fishery formally began in 1938, and during the 1940s and 1950s almost all of the landings were by Maine vessels from Portland and smaller Maine ports further east. This was an inshore winter fishery, directed towards egg-bearing females in inshore waters (Scattergood 1952). New Hampshire vessels entered the fishery in 1966, but throughout the 1960s and 1970s New Hampshire landings were minor. Landings by Massachusetts vessels were insignificant until 1969, but in the early 1970s the fishery developed rapidly, with MA landings increasing from 14% of the Gulf of Maine total in 1969 to over 40% in 1974-1975. In contrast to the historical wintertime Maine fishery, these vessels fished continually throughout the year and made significant catches during summer months A wide variety of vessels have been used in the fishery (Bruce 1971; Wigley 1973). The predominant type during the 1960s and 1970s appears to have been side-rigged trawlers in the 14-23 m range. During the 1980s and 1990s, side trawlers either re-rigged to stern trawling, or retired from the fleet. Currently, the shrimp fleet is comprised of lobster vessels in the 9-14 m range that re-rig for shrimping, small to mid-sized stern trawlers in the 12-17 m range, and larger trawlers primarily in the 17-24 m range. The otter trawl remains the primary gear employed and is typically chain or roller rigged, depending on area and bottom fished. There has been a trend in recent years towards the use of heavier, larger roller and/or rockhopper gear. These innovations, in concert with substantial improvements in electronic equipment, have allowed for much more accurate positioning and towing in formerly unfishable grounds, thus greatly increasing the fishing power of the Gulf of Maine fleet.
A small pot fishery has also existed in mid-coastal Maine since the 1970s, where in many areas bottom topography provides favorable shrimp habitat yet is too rough or restricted for trawling. The trapped product is of good quality, as the traps target only female shrimp once they have migrated inshore. The trap fishery has landed as much as 9% of the landed total, but the annual average is usually around 5%. There is some indication that trap fishing for shrimp has grown in a few areas such as South Bristol (Lower mid-coast Maine). As the trap fishery is dependent on the availability of shrimp in a specific area, there is apparently a shorter season for traps than for draggers. The majority of the shrimp trappers also trap lobsters.
318 36th SAW Consensus Summary
Management measures currently in place include season length (varying from year to year within a time frame of December 1 through May 31), gear restrictions, licensing, and mandatory reporting. Legal restrictions on trawl gear require a minimum 1.75 inch stretch mesh net and the use of a finfish separator device known as the Nordmore grate with a maximum grate spacing of 1 inch.
4.0 Habitat Description Pandalus borealis has a discontinuous distribution throughout the North Atlantic, North Pacific, and Arctic Oceans. In the Gulf of Maine, northern shrimp populations comprise a single stock (Clark and Anthony 1981), which is concentrated in the southwestern region of the Gulf (Haynes and Wigley 1969; Clark et al 1999). Water temperature, depth, and substrate type have all been cited as important factors governing shrimp distribution in the Gulf of Maine (Haynes and Wigley 1969; Apollonio et al. 1986; Clark et al. 1999 ).
Temperature The most common temperature range for this species is 0-5 °C (Shumway et al 1985). The Gulf of Maine marks the southern-most extent of this species range in the Atlantic Ocean, and seasonal water temperatures in many areas regularly exceed the upper physiological limit for northern shrimp.
This environmental limitation restricts the amount of available habitat occupied by this species to the western region of the Gulf (west of 680 W) where bottom topography and oceanographic conditions create submarine basins protected from seasonal warming by thermal stratification. The deep basins act as cold water refuges for adult shrimp populations (Apollonio et al 1986). In the northeastern region of the Gulf, large shrimp populations do not persist because bottom waters are not protected from seasonal warming due to continual mixing from intense tidal currents nearer to the Bay of Fundy.
Depth In the Gulf of Maine, northern shrimp are most frequently found from about 10 m to over 300 m (Haynes and Wigley 1969), with juveniles and immature males occupying shallower, inshore waters and mature males and females occupying cooler, deeper offshore waters for most of the year (Apollonio and Dunton 1969; Haynes and Wigley 1969, Apollonio et al 1986). During the summer months, adult shrimp inhabit water from 93-183 m (Clark et al. 1999); ovigerous female shrimp are found in shallower near-shore waters during the late winter and spring (Clark et al. 1999) when their eggs are hatching.
Substrate Within its preferred temperature range, northern shrimp most commonly inhabit organic-rich, mud bottoms or near-bottom waters, where they prey on benthic invertebrates; however, the shrimp is not limited to this habitat and has been observed on rocky substrates (Schick 1991). Shrimp distribution in relation to substrate type determined by spring, summer, and autumn fisheries-independent trawl surveys clearly show northern shrimp primarily occupy areas with fine sediments (sand, silt, and clay). Shrimp are often associated with biotic or abiotic structures such as cerianthid anemone 36th SAW Consensus Summary 319
(Langton and Uzmann 1989) and occasional boulders in these fine sediment habitats (Daniel Schick, Maine Department of Marine Resources, pers. comm.).
5.0 Data Sources 5.1 Commercial 5.1.1 Data Collection Methods Commercial landings by state and month have been compiled by NMFS port agents from dealer reports. It is likely that catches sold to the small peddler market have been unreported, as well as some of those sold to those dealers (non-federally permitted) who are not required to report.
These data were used for annual stock assessments until 2001, when vessel trip reports (VTRs) were found to be more complete. Small Maine vessels that did not have federal permits were not required to fill out VTRs until 2000. Landings have been calculated from VTRs for use in assessments in 2001 and 2002.
A port sampling program was established in the early 1980s to characterize catch at length and developmental stage, as well as to collect effort and fishing depth and location data. Samplers strive to achieve representative sampling by maintaining up-to-date lists of active buyers and visiting ports in proportion to their landings activity. Sampling consists of interviewing boat captains and collecting a 1 kg sample of shrimp from each catch. The samples are separated and weighed back at the lab by species, sex and development stage. Measurements are made of all shrimp dorsal carapace lengths to the nearest half mm. The numbers of shrimp measured, and a calculation of sampling intensity are shown in Tables 2 and 3.
5.1.2 Landings Small quantities of northern shrimp have been incidentally caught in New England otter trawl fisheries since 1905 (Scattergood 1952). A directed winter fishery in coastal waters developed in the late 1930s, which landed an annual average of 63 mt from 1938 to 1953, but no shrimp were landed from 1954 to 1957 due to low inshore availability (Wigley 1973; Table 1a). The fishery resumed in 1958, and landings increased steadily to a peak of 12,100 mt during the 1969 season (August 1968 to July 1969) as an offshore, year-round fishery expanded. After 1972, landings declined rapidly, and the fishery was closed in 1978. The fishery reopened in 1979 and seasonal landings increased gradually to 5,300 mt by 1987 and averaged 3,300 mt from 1988 to 1994 (Table 1a&b). Seasonal landings increased to 6,500 mt in 1995 and to 9,200 mt in 1996, which was only exceeded by the five years of landings prior to the late 1970s stock collapse. Landings declined between 1996 and 1999 to 1,900 mt. This was followed by a slight increase to 2,400 mt in the 2000 season. Landings dropped during 2001 to 1,400 mt and in 2002 to a low of 400 mt for the 25-day 2002 season. The 2002 landings were the lowest northern shrimp landings since the fishery was closed in 1978 (Table 1a, Figure1).
320 36th SAW Consensus Summary
Maine landings comprised 75% of season totals during 1984-1996. The proportional distribution of landings among the states has shifted gradually since the 1980s when Massachusetts accounted for about 30% of the catch. In 2001 and 2002, the proportional distribution of landings was still greatest for Maine but was then followed by NH with 18% (2001) and 13%
(2002). Massachusetts landings made up 5% of the 2001 landings and 1.5% of the landings in 2002 (Tables 1a&b). The majority of landings generally occur in January and February (Table 1b, Figure 2). Since the 1999 season, there has been a reduction in the number of months fished.
Size composition data (Figures 3, 4a&b), collected since the early 1980's, indicate that trends in landings have been determined primarily by recruitment of strong (dominant) year classes.
Landings more than tripled with recruitment of a strong 1982 year class in 1985 and 1986. The 1987 season landings were supported in large part by mature females (assumed age 5) from the 1982 year class. Landings declined sharply in 1988 with the passage of the 1982 year class through the fishery. A strong 1987 year class began to recruit to the fishery in spring of 1989 and was a major contributor to the 1990-1992 fisheries. The 1992 year class was the first year class of notable size since 1987 and began recruiting to the fishery in March and April 1995. The 1992 year class was supplemented by a moderate sized 1993 year class, which partially supported the relatively large annual landings in 1995, 1996 and 1997. The early months of the 1998 season showed high catches from the last of the 1993 year class coming ashore as second year females. Landings were low in the 1999 season due to very poor recruitment in 1994 and 1995, and moderate recruitment in 1996. The increase in landings observed in 2000 was dominated by first year berried females from the 1996 year class. The poor landings observed in 2001 were composed primarily of egg-bearing females from the 1996 yearclass landed early in the season, and males caught in January, March, and April, the males accounting for approximately 30% of the catch during these months and representing the 1999 year class. In the 2002 fishery, the 1997 and 1998 yearclasses (4- and 5- year old females) continued to be weak, and the moderate 1999 yearclass (3-year old males, transitionals, and early-maturing females) dominated the catches.
Two-year old shrimp (2000 yearclass) were generally absent, but a noticeable quantity of 1-year-old shrimp (2001 yearclass) were caught (Figures 3, 4a).
Landings from January to March consist primarily of mature female shrimp (presumably ages 3 and older) and December, April, and May landings have included higher proportions of males (assumed ages 1 and 2; Figure 4b). These patterns reflect shifts in distribution of fishing effort in response to seasonal movements of mature females: inshore in early winter and offshore after their eggs hatch.
Catch in numbers was derived by dividing landed weight (Table 1b) by mean individual weights (Table 4) by year, state, and month. The general patterns in size composition of landings are reflected in mean weight of individual shrimp landed by year, state, and month: the size of landed shrimp generally increases from December to January, peaks in February, and decreases through the spring. Three percent of total landings for 1984-1996, were from specific year-state-month strata with no port samples, generally at the beginning or the end of a fishing season. Mean weight for these non-sampled landings was estimated by a general linear model of mean weight incorporating year, month and state effects. Some June landings, which had no associated port 36th SAW Consensus Summary 321
samples (126 mt, 0.2% of total time series landings), were described using May samples within the same year and state.
5.1.3 Commercial Discards and Bycatch Sea sampling observations on shrimp otter trawl trips from 1984 to 1996 indicate that weight of discards is less that 1% of total catch in all years (Table 5). Large year classes appear to contribute some discards as age-2 (e.g., the 1992 cohort produced almost 1% discards in 1994).
Industry representatives report substantial discards of shrimp in the small-mesh whiting fishery east of Jeffreys Ledge. Sea sampling observations from finfish trawl fisheries in the Gulf of Maine suggest that bycatch of northern shrimp was inconsequential from 1984-1994. However, in 1995 and 1996 the amount of discarded shrimp per trip increased considerably, and the increase was from small-mesh trips sampled in the area of Jeffreys Ledge. Although the observed discards increased, the total was less than 60 kg per observed trip. Unfortunately, no shrimp lengths were measured during sea sampling, and estimates of total number discarded would be difficult.
5.1.4 Commercial Catch Rates and Fishing Effort Maine trapping operations accounted for 4% to 8% of the state's total number of trips from 1987 to 1994, and for 15.9, 16.9, and 18.0% in 2000, 2001, and 2002 respectively, according to 2000-2002 Vessel Trip Report (VTR) data.
Since the late 1970's, effort in the fishery (measured by numbers of trips in which shrimp gear is used) has increased and then declined on two occasions. The total number of trawl trips in the fishery peaked at 12,285 during the 1987 season (Table 6, Figure 5). Increases in season length, shrimp abundance and record ex-vessel prices coupled with reduced abundance of groundfish all contributed to this increase. Effort subsequently fell to an average of 9,500 trips for the 1988, 1989, and 1990 seasons, fell further to an average of 7,900 trips in the 1991 and 1992 seasons, and declined to 6,000 trips in the 1994 season. Effort nearly doubled between 1994 and 1996 and then declined again from the 1996 level of 11,791 to 3,811 trips in 1999, 3,335 in 2000, 3,527 in 2001, and 870 in 2002.
Approximately 310 vessels participated in the shrimp fishery in 1997, 260 in 1998, and about 238 in 1999. In 1999, the majority (181) were from Maine, while the number of vessels from New Hampshire ports remained at about 30, and the numbers from Massachusetts declined from 33 vessels in 1998 to 27 in 1999. In 2000 and 2001 there were 285 and 274 vessels participating, respectively. In 2002, there were 133 vessels from Maine, 6 from Massachusetts, and 21 from New Hampshire, for a total of 160 vessels that reported shrimp trips.
Prior to 1994, effort (numbers of trips by state and month) was estimated from landings data collected from dealers, and landings per trip information (LPUE) from dockside interviews of vessel captains:
Effort = LPUE Landings 322 36th SAW Consensus Summary
Beginning in the spring of 1994, a vessel trip reporting system (VTR) supplemented the collection of effort information from interviews. From 1995 to 2000, landings per trip (LPUE) from these logbooks were expanded to total landings from the dealer weighouts to estimate the total trips:
Total.Landings Total .Trips = VTR.Trips VTR.Landings Since 2000, VTR landings have exceeded dealer weighout landings, and the above expansion is not necessary. However, VTRs for 2002 are still being received. The vessel logbook database is currently incomplete and has not been thoroughly audited (for an evaluation of vessel trip report data see NEFSC 1996). Therefore, landings and effort estimates reported here for recent years should be considered extremely preliminary. The 1996 assessment report (Schick et al. 1996) provides a comparison of 1995 shrimp catch and effort data from both the NEFSC interview and logbook systems and addresses the differences between the systems at that time. It showed a slightly larger estimate from the logbook system than from the interview system. Thus effort statistics reported through 1994 are not directly comparable to those collected after 1994. However, patterns in effort can be examined if the difference between the systems is taken into account. An additional complication of the logbook system is that one portion of the shrimp fishery may not be adequately represented by the logbook system during 1994-1999. Smaller vessels fishing exclusively in Maine coastal waters are not required to have federal groundfish permits and were not required to submit shrimp vessel trip reports until 2000. In the 1994-2000 assessments, effort from unpermitted vessels was characterized by catch per unit effort of permitted vessels.
Seasonal trends in distribution of effort can be evaluated from port interview data. The relative magnitude of offshore fishing effort (deeper than 55 fathoms) has varied, reflecting seasonal movements of mature females (inshore in early winter and offshore following larval hatching),
but also reflecting harvesters choices for fishing on concentrations of shrimp. As an example, the 1994 fishery stayed in deep water only through the beginning of January, shifted inshore through the middle of March and then moved into deeper water for the duration of the season.
The 1995 fishing patterns revealed an early inshore migration in December and an early offshore migration with most fishing occurring offshore even during March. The 1999 seasons effort was all offshore in December and almost all offshore in January. Effort moved inshore in February and remained primarily inshore throughout March. Effort in April and May was all offshore.
This distribution of effort reflects the fact that the main body of shrimp available to the fleet was from the three-year-old 1996 year class, and they were split between transitionals that remained offshore and early maturing females that made some shoreward migration during the winter.
During the 2000 season, effort was almost entirely inshore in January and February and increasingly offshore in March. In 2001, 17% of fishing was offshore in January, decreasing to 5% in February, increasingly offshore (78%) in March and entirely offshore in April, from Maine port interview data. In the 2002 season, 100% of fishing was inshore in February, and 20% was inshore in March, from Maine, New Hampshire, and Massachusetts port interview data.
Catch per unit effort (CPUE) indices have been developed from NMFS interview data (1983-1994) and logbook data (1995-2002) and are measures of resource abundance and availability (Figure 5).
They are typically measured in catch per hour or catch per trip. A trip is a less precise measure of 36th SAW Consensus Summary 323
effort, because trips from interviews and logbooks include both single day trips and multiple day trips (in the spring), and the proportion of such trips can vary from season to season.
Pounds landed per trip (Figure 5) increased from 844 pounds in 1983 to over 1,300 pounds in 1985 when the strong 1982 year class entered the fishery. CPUE subsequently dropped to below 750 pounds/trip in 1988 but increased to 1,050 pounds in 1990 with entry of the strong 1987 year class.
This index averaged 980 pounds between 1991-1992, declined to 767 pounds in 1993, and increased in 1994 to 1,073 pounds. The 1995, 1996 and 1997 CPUEs, from logbooks, rose sharply to 1,362 pounds in 1995, rose again to 1,714 in 1996 and declined to 1,454 in 1997. The CPUEs for 1996 and 1997 were the highest since the early 1970s. The 1998 CPUE was 1,317, showing a continued high level compared to earlier years and the 1999 CPUE dropped to 1,067 pounds per trip, which is still considerably higher than in previous years with poor recruitment. The 2000 CPUE increased to 1,444 pounds per trip. In 2001, the catch per trip dropped to 756 pounds per trip, the lowest since 1993. In 2002, the catch per trip was 872 pounds (Figure 5).
More precise CPUE indices (pounds landed per hour fished) have also been developed for both inshore (depth less than 55 fathoms) and offshore (depth more than 55 fathoms) areas using information collected by Maine's and New Hampshire's port sampling programs, and agree well with the (less precise) catch per trip data from logbooks (see text table below and Figure 5).
Inshore CPUE for 2002 was 223 lbs/hr, offshore was 91, and the season average was 194 lbs/hr, (see table below.)
Higher catch rates (per hour) may reflect increased biomass or denser aggregations of shrimp, which make them more available to the gear. Another possible cause for an increase in catch rate is an increase in vessel fishing power, which can not be assessed independently. Higher catch rates (per trip) may indicate a higher than average incidence of multiple-day trips. For these reasons, attempting to interpret catch rate data is not for the faint of heart.
ME/NH CPUE in lbs./hour towed, from port sampling. Catch in lbs./trip is from NMFS weighout and logbook data.
Year Inshore (<55F) Offshore (>55F) Total Catch/trip 1991 94 152 140 988 1992 132 93 117 974 1993 82 129 92 767 1994 139 149 141 1,073 1995 172 205 193 1,362 1996 340 203 251 1,714 1997 206 192 194 1,454 1998 158 151 154 1,317 1999 159 146 152 1,067 2000 288 337 292 1,444 2001 100 135 109 756 2002 223 91 194 872 324 36th SAW Consensus Summary
5.1.6 Fishery Selectivity Selectivity of commercial trawl gear was estimated experimentally in July 1995, twenty miles south of Boothbay Harbor (Schick and Brown 1997). Five paired tows were sampled with a trouser trawl over a two-day period. The trouser body consisted of 47.6 mm (1-7/8") diamond polypropylene mesh as did the septum, which divided the trawl in half vertically. The control codend was 12.7 mm (1/2") square polypropylene mesh with a 6.4 mm (1/4") mesh liner. The experimental codend consisted of 47.6 mm (1-7/8") diamond polypropylene mesh.
Three five-kg samples from each codend were bagged, labeled, stored on ice at sea, and then frozen. Mid-dorsal carapace length (CL) was measured for 500 shrimp from each sample.
Sample length frequencies were expanded to total catch length frequencies using the ratio of sample weight to catch weight. Observed retention ratios at length were derived by dividing the number at length from the experimental codend (large mesh) by the number at length from the control codend (small mesh). The average of five ratios, one from each tow, was used to fit a selectivity ogive (Nicolajsen 1988):
P = 1/(1+e-(aCL+b)) (1) where P is the proportion retained at size. The parameters a and b were estimated using logistic regression. The CL range used in the regression was 13.5-28.5 mm CL.
5.2 Recreational A very limited recreational fishery exists for northern shrimp. This fishery, using traps, has been for personal use and has not been licensed.
5.3 Fishery-Independent Survey Data Trends in abundance have been monitored since the late 1960's using data collected by NEFSC spring and autumn bottom trawl surveys and summer surveys by the state of Maine and jointly by the NSTC and NEFSC (Figure 6).
Maine Survey Maine conducted summer surveys in the Gulf of Maine from 1967 to 1983. Fixed stations were sampled with an otter trawl during daylight at locations where shrimp abundance was historically high (Schick et al. 1981; Figure 7). The Maine survey biomass index began declining in 1968, and depicts the stock collapse in the late 1970s (Figure 6; Clark 1981, 1982; Schick et al. 1981).
Groundfish Surveys NEFSC autumn bottom trawl surveys have been conducted since 1963, and spring bottom trawl surveys have been conducted since 1968. Stations are sampled from Cape Hatteras to Nova Scotia according to a stratified random design (Figure 8; Despres et al. 1988). Although the groundfish surveys catch relatively fewer northern shrimp and have more measurement error, 36th SAW Consensus Summary 325
they represent a longer time series. Correspondence among research surveys and fishery indices of abundance suggests that the autumn survey tracks resource conditions more closely than the spring survey (Clark and Anthony 1980; Clark 1981, 1982). The autumn survey indicates a precipitous decline from peak biomass in the 1960's and early 1970s to 3% of peak levels in the late 1970's. The index subsequently increased in the 1980s and, since the mid 1980s, has fluctuated at approximately 40% of the peak levels observed in the 1960s (Figure 6).
NSTC Shrimp Survey The NSTC shrimp survey has been conducted each summer since 1983 aboard the R/V Gloria Michelle employing a stratified random sampling design and gear specifically designed for Gulf of Maine conditions (Blott et al. 1983, Clark 1989). The summer survey is considered to provide the most reliable information available on abundance, distribution, age and size structure and other biological parameters of the Gulf of Maine northern shrimp resource. Indices of abundance and biomass are based on catches in the strata that have been sampled most intensively and consistently over time (strata 1, 3 and 5-8; Figure 9). Survey catches have been highest in strata 1, 3, 6 and 8, the region from Jeffreys Ledge and Scantum Basin eastward to Penobscot Bay. The 1983 survey did not sample strata 6-8.
5.3.4 Biomass Indices Biomass indices for the three surveys are presented in Figures 6 and 11 and Table 10.
The statistical distribution of the summer survey catch per tow (in numbers) was investigated to determine the best estimator of relative abundance. Catches within strata were distributed with significant positive skew, and arithmetic stratum means were correlated to stratum variances.
Log transformed catches (Ln[n+1]) were more normally distributed. Log transformation is a common practice for estimating relative abundance from trawl surveys, because stratum means and variances are seldom independent, and log transformation generally normalizes observations, renders the variance independent, and reduces anomalous fluctuations (Grosslein 1971).
Geometric means were estimated with more precision (mean CV=2.4%) than arithmetic means (mean CV=13.5%). Therefore, stratified geometric mean catch per tow was used to estimate relative abundance. The nontransformed and transformed indices have different magnitudes and temporal patterns, particularly in recent years (Table 7, Figure 10). Annual variation in the difference between the two series reflects varying degrees of skewness, or patchiness of shrimp aggregations from year to year, which is consistent with observations from the fishery (i.e., the shrimp appear to be more patchily distributed when abundance is low).
Shrimp summer survey catches by length and developmental stage (Figure 12) reflect the predominance of the strong 1982, 1987, 1992, and 2001 cohorts in the stock. Although size at age-1.5 varies from year to year, discrete length modes indicate the relative abundance of age-1.5 shrimp (generally around 12-18.5 mm CL) and age-2.5 shrimp (generally 19-23 mm CL). Length modes for older cohorts overlap extensively.
A selectivity method was used to derive indices of recruits and fully-recruited shrimp from survey length frequencies (NEFSC 1995). The number per tow at length was partitioned into 326 36th SAW Consensus Summary
three components: fully-recruited, recruits, and pre-recruits (as illustrated in Figure 13). The fishery selectivity curve (Schick and Brown 1997, described above) was used to define fully-recruited shrimp. The products of selectivity at length and survey catch per tow at length were summed to derive total catch per tow of fully-recruited shrimp. The carapace length of each interval was increased by one year of growth according to a vonBertalanffy growth curve:
CLt+1 = CLt + (CL -CLt) (1-e-K) (2) where CL=35.2 and K=0.36 (McInnes 1986) to estimate fishery selectivity after a year of growth. The remaining length frequency of recruits and pre-recruits was then multiplied by the end-of-year selectivity at length to obtain an index of recruits. Using the selectivity method, age-classes recruit to the fishery over several years, and recruitment in each year is composed of several cohorts. Therefore, the definition of recruitment used in this assessment is not synonymous with year-class strength (previous northern shrimp assessments defined recruitment as age-2.5 abundance).
Mean weight of recruits and fully recruited shrimp were estimated according to length-weight equations for each developmental stage from Haynes and Wigley (1969) and 1990 northern shrimp survey observations.
ABUNDANCE AND FISHING MORTALITY ESTIMATES 6.0 Methods 6.1 Models Descriptive information for the Gulf of Maine shrimp fishery (total catch, port sampling, trawl selectivity, survey catches, and life history studies) were modeled to estimate fishing mortality, stock abundance, and candidate target fishing levels. The Collie-Sissenwine Analysis (CSA)
(Collie and Sissenwine 1983; Collie and Kruse 1998) tracks the removals of shrimp using summer survey indices of recruits and fully-recruited shrimp scaled to total catch in numbers.
This modified DeLury model was applied to the Gulf of Maine northern shrimp fishery:
Nt+1 = (Nt + Rt - Ct) e-M (3) where fully-recruited abundance at the end of the year (Nt+1) equals fully-recruited abundance at the beginning of the year (Nt), plus recruitment (Rt), minus catch (Ct), all reduced by one year of natural mortality (e-M).
Natural mortality (M) was assumed to be 0.25, as approximated from the intercept of a regression of total mortality on effort (Rinaldo 1973, Shumway et al. 1985). Estimates of Z for age-2+
shrimp from visual inspection of length modes from the Maine summer survey was 0.17 from 1977 to 1978, when the fishery was closed (Clark 1981, 1982), suggesting, for the population as 36th SAW Consensus Summary 327
a whole, M is low relative to estimates for other Pandalus stocks, which range from 0.2 to 0.8 (ICES 1977, Abramson 1980, Frechette and Labonte 1980).
Catch was assumed to be taken at mid-year, whereby the summer survey marks the beginning of the survey year (August 1), and catch was taken on February 1 of the next calendar year (which was based on the time of 50% cumulative seasonal catch for 1985-1996 (Figure 2):
Nt+1 = [(Nt + Rt)e-0.5M - Ct] e-0.5M (4) so that recruited shrimp (Nt + Rt) experience a half-year of natural mortality (e-0.5M), catch is removed, then the survivors [(Nt + Rt)e-0.5M - Ct] experience another half-year of natural mortality.
Abundance is related to survey indices of relative abundance:
nt' = qnNt et (5) and rt' = qrRt et (6) where rt' and nt' are observed survey indices of recruits and fully-recruited shrimp, q is catchability of the survey gear, and et and et are lognormally distributed measurement errors.
The process equation is derived by substituting survey indices into equation 4 and including lognormally distributed process error (et):
nt+1 = [(nt + rt/sr)e-0.5M - qnCt] e-0.5M et (7) where s r = qr / qn (8) is the relative selectivity of recruits to fully-recruited shrimp. Selectivity studies (Blott et al.
1983) and survey catch at length suggest that age-1.5 sized shrimp are sampled less efficiently than age-2+ shrimp, because total catch per tow is greater at age-2.5 than at age-1.5 for some cohorts (Figure 12). For the shrimp survey, there are two components to sr: selectivity and availability of age-1.5 shrimp. The 32mm codend mesh in the survey trawl may not retain some small shrimp, and in some years, age-1.5 males may not completely migrate from inshore areas to the survey strata (Figure 9). Precise estimation of survey selectivity at size was not possible due to high variability in catch at size and few comparative experimental tows (Blott et al. 1983). For the present analysis, sr was approximated from the relative sampling efficiency of <19mm CL shrimp to that of larger shrimp, and the relative proportions of those sizes comprising total recruits and fully recruited indices.
The parameters nt, rt, and qn were estimated by iteratively minimizing the sum of measurement errors (equations 5 and 6) and process errors (from equation 7) for the entire time series. Total mortality (Z) and fishing mortality (F) were calculated from abundance estimates:
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ZR+N,t = Ln [(Nt + Rt) / Nt+1 ] (9) and FR+N,t = ZR+N,t - M (10)
The fishing mortality can be partitioned according to the average partial recruitment (p) of recruits over the survey year:
FN,t = [FR+N,t (Rt+Nt)] / p Rt (11) and FR,t = p FN,t (12)
Average partial recruitment was derived from the schedule of growth to fully-recruited size over the survey year, as approximated by observations of monthly growth of age-1.5 shrimp from a mean carapace length of 14.5mm in July to 21.9mm CL the next July (Haynes and Wigley 1969).
Results CSA results are summarized in Tables 8 & 9 and more detailed model output is reported in Appendix A. Parameters were relatively well-estimated. Coefficients of variation for fully-recruited abundance estimates ranged from 18% to 25%, estimates of recruitment were slightly less precise (CV=23% to 26%), and qn was estimated with moderate precision (CV=16%).
Defining correlation between parameters (Appendix A) as:
rij = CVij/(CVii*CVjj) 0.5 (13) there were no large correlations among the 38 parameter estimates (all rs < 0.4). Residuals ranged from -0.33 to 0.35 without significant annual patterns, indicating that the data fit the model well (Figures 14, 15).
Estimates of recruitment to the fishery averaged 0.8 billion individuals, peaked at 1.3 billion before the 1990 fishing season, but declined steadily to less than 0.4 billion before the 2002 fishing season. The current estimate indicates a sharp rise up to 1 billion prior to the next scheduled fishing year (2003). Fully-recruited abundance averaged 1.0 billion individuals and peaked at 1.5 billion before the 1991 season. Fully-recruited abundance decreased to a time series low of less than 0.4 billion in 2000 and increased to 0.6 billion in the current year. Total stock biomass estimates averaged about 13,200 mt, with a peak at over 22,000 mt before the 1991 season, and a decrease to a time series low of 5,600 mt in 1999. Total stock biomass has increased over the last three years to its current value of 9,200 mt (Tables 8a&b, Figure 14).
Annual estimates of fishing mortality (F) averaged 0.34 (26% exploitation) for the 1985 to 1995 fishing seasons, peaked at 0.87 (52% exploitation) in the 1997 season and decreased to 0.28 (22% exploitation) in the 2000 season (Table 8a, Figure 14). In 2001, F rose to 0.40 (29%
exploitation). In the most recent fishing year (2002) the short season and poor stock condition (in terms of exploitable shrimp) along with an exceptional recruitment pulse resulted in F estimates for the terminal year (2002) of -0.01. While the removal of at least 375 mt of shrimp 36th SAW Consensus Summary 329
by the fishery indicate some level of F, the slightly negative value is analytically plausible. In addition to the relative lack of precision in estimating the terminal year F, there is the possibility that either M is not the constant 0.25 assumed, and/or catch is not measured precisely. The three year (2000 - 2002) average is 0.22 (18% exploitation). The recent pattern in F reflects the pattern in nominal fishing effort (Figure 5). Estimates of mortality in the first and last years are the least reliable in CSA analysis, because they are linked to one adjacent year rather than two. Averages of terminal mortality estimates (e.g., F00-01=0.65 or F99-01=0.54) are less sensitive to measurement error in the 2002 survey observation of fully-recruited shrimp or reporting of catch in 2002.
However, averaging F01 with previous years may be inappropriate because of the apparently significant decrease in effort and exploitable shrimp stock. Total mortality estimates were within the range of previous estimates using visual inspection of survey length frequencies (previous NSTC reports), Shepherds Length Composition Analysis (Terceiro and Idoine 1990) and MULTIFAN (Fournier et al. 1991).
Two thousand bootstrap replicates, which were derived by randomly resampling model residuals, suggest that estimates of abundance, biomass and mortality were relatively precise. The median bootstrapped value for the final year (F01) was -0.01 with an 80% confidence interval of -.0.12 to 0.21 (Figure 15). Two approaches were examined to define a multiple year average F. The first examined the distribution of bootstrap estimates from all applicable years as if they all represented estimates of the current fishing mortality (Figure 16a). The second approach was to average the estimates for each bootstrap iteration, and examine the resultant distribution (Figure 16b). From this, while the medians of the two approaches agree, it is clear there is a loss of precision of the second due to the reduction of the tails through averaging (Figure 16c). The result for both approaches using a two and three year average are shown below:
1999-2001 1999-2001 2000-2001 2000-2001 Average All Average All 10th Pctl 0.15 -0.03 0.05 -0.07 Median 0.25 0.26 0.17 0.17 90th Pctl 0.35 0.48 0.28 0.39 Abundance estimates were not bias-corrected, because estimates of bias were not substantial
(<10% in most years).
Retrospective Analysis Comparison of results from 10 retrospective CSA runs to the results reported above was investigated to assess the stability of estimates in the last year of the analysis and the possibility that terminal mortality estimates are systematically inconsistent. The analysis was performed by sequentially deleting the last year of survey and catch data (for five years) to create a retrospective series of CSA estimates as well as runs that similarly truncated the first year (Table 9, Figure 17a-d). Terminal mortality estimates (both initial and final year) were quite stable in most years with minimal retrospective differences in F (Figure 17a). Similar stability was seen in estimates of abundance and biomass (Figures 17b-c). The NLSS estimate of q was also very stable for the series of retrospective analyses (Figure 17d).
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Confirmatory Analysis An alternative method of estimating stock size and F was explored to corroborate results from CSA. A nonequilibrium surplus production model (Prager 1994, 1995) was fit to seasonal catch and survey biomass indices from 1968 to 1996 (summarized in Table 10, more detailed output in Appendix B). The model assumes logistic population growth, in which the change in stock biomass over time (dBt/dt) is a quadratic function of biomass (Bt):
dBt/dt = rBt - (r/K)B2t (14) where r is intrinsic rate of population growth, and K is carrying capacity. For a fished stock, the rate of change is also a function of F:
dBt/dt = (r-Ft)Bt - (r/K)Bt2 (15)
For discrete time increments, such as annual fishing seasons, the difference equation is:
Bt+1 = Bt + (r-Ft)Bt - (r/K)Bt2 (16)
Initial biomass (B1), r, and K were estimated using nonlinear least squares. The fall groundfish survey catch per unit effort (CPUE) contributed to the total sum of squares as a series of observed effort (E=CPUE/C); the Maine summer survey and the NSTC shrimp surveys contributed as independent indices of biomass at the start of the fishing season. Note that no assumption about M is needed for the biomass dynamics analysis.
One survey observation (fall 1982) was a statistical outlier, and the pattern of residuals from Maine and NSTC surveys suggest autocorrelation (Figure 18). A fair portion of the variance in the fall and Maine surveys was explained by the model (R2=0.5 an 0.6, respectively), but much of the variation in the summer shrimp survey was not resolved (R2=0.3). The model did not account for peaks in biomass from strong recruitment.
Estimates of F from the biomass dynamics model generally confirm the pattern and magnitude of estimates from the CSA model; F02 was the lowest value since 1983 (Figure 19). Recruitment of the strong 1982, 1987, 1992, and 2001 cohorts is not as pronounced in the biomass trajectory from the production model, because dynamic recruitment is not explicitly estimated, as it is in the CSA. The biomass dynamics model suggests that a maximum sustainable yield (MSY) of 5,000 mt can be produced when stock biomass is approximately 29,900 mt (BMSY) and F is approximately 0.17 (FMSY; Figure 20). However, BMSY was only exceeded by the first three years in the analysis, which are not reliable (Prager 1994, 1995).
Survey residuals were randomly resampled 1000 times to estimate precision and model bias.
Bootstrap results suggest that r, MSY and FMSY were relatively well estimated(relative interquartile ranges were <16%, and bias was <4%). Estimates of K, BMSY, and qs were moderately precise (relative IQs were 20-32%, bias was <8%), and B1 was not as precisely estimated (relative IQ=43%). The ratio of F/FMSY in 2002 was estimated with moderate 36th SAW Consensus Summary 331
precision(relative IQ = 30%, bias = -3.44%.). Similarly, B\ BMSY in 2002 was estimated with moderate precision. (relative IQ =36%, bias = -9.12%)
8.0 Biological Reference Points Yield per recruit (Thompson and Bell 1934) and percent maximum spawning potential (Gabriel et al. 1989) were estimated for the Gulf of Maine northern shrimp fishery (Table 11, Figure 21).
Yield and egg production were derived as a function of abundance at the time of spawning (i.e.,
abundance at the start of the year, approximately February 1) to reflect size and weight at age during spawning and the fishery. The model assumes annual growth and ontogenetic transition occur before oviposition and the onset of the fishing season. As described above, M was assumed to be 0.25 (Rinaldo 1973). Length at age was estimated using the vonBertalanffy growth parameters L=35.2 mm and K=0.36 (McInnes 1986). Proportion female at the time of hatch was the average of 1984-1996 observed sex ratios at length from the summer survey, applied to a carapace length which was increased by a half-year of growth using equation (2).
Selectivity at size was estimated using the selectivity curve from Schick and Brown (1997),
described above. Mean weight at length for males and females was estimated using relationships developed by Haynes and Wigley (1969). Estimates of fecundity at oblique CL were from a linear relationship developed by Apollonio et al. (1984).
Yield per recruit was maximized at F=0.77 (Fmax) (Table 11). The increase in yield per unit F decreased to one tenth the initial increase at F=0.46 (F0.1). Maximum spawning potential (i.e.,
with no F) was 2,395 eggs per recruit. Spawning potential was reduced by half at F=0.25 (F50%).
Information from the stock collapse in the 1970s may provide guidance on the level of sustainable F for Gulf of Maine northern shrimp. Biomass indices from the Maine survey and the biomass dynamics model suggest that biomass was declining as early as 1968. Log catch ratios of assumed age-2+ shrimp from survey length frequencies suggested that F was 0.7 to 0.8 from 1968 to 1970, and continued annual harvests of over 5,000 mt drove F to an annual average of 1.6 from 1971 to 1975 (Clark and Anthony 1980). Estimates of F from the first several years of the production model (e.g., 1968-1972) are imprecise and are not considered reliable (Prager 1994, 1995), but F estimates for 1973-1975 ranged from 0.6 to 1.1 (Figure 19). According to the present egg production per recruit analysis and historical F estimates, the stock was not replacing itself when spawning potential was reduced to less than 18% of maximum, and the stock collapsed when egg production was reduced further. Therefore, F20% may be an appropriate overfishing threshold, which would result in target Fs well below 0.6.
The survey index of age-1.5 shrimp biomass appears to be correlated to the biomass index of females from two years previous (Figure 22). A survey index of egg production, derived as the sum of catch per tow of females at length multiplied by fecundity at length (Apollonio et al.
1984), had a similar relationship to recruitment. Prior to 2001, the two dominant cohorts in the time series were produced when spawning stock biomass was among the highest levels in the time series. When spawning stock indices were greater than 6 kg/tow, two of four dominant cohorts were produced. These relationships suggest that poor recruitment is more likely at low levels of spawning stock biomass and egg production, and adequate egg production per recruit 332 36th SAW Consensus Summary
should be conserved. The last three years average spawning stock index was 2.5 kg/tow. Prior to 2001 all cohorts produced by spawning indices of 3kg/tow or less were below average. However in 2001, the below average SSB of 2.8 kg/tow produced an exceptionally high recruitment index.
Based on this it is currently difficult to estimate a SSB/R relationship that is representative of this stock (see SARC36 Working Paper C3).
Survey indices of egg production, recruitment, and spawning biomass (Figure 22), and historical estimates of spawners and recruits (Richards et al. 1996, Richards and Clark 1996) suggested that at median survival rates, greater than 50% of maximum spawning potential was needed to replace the stock. Provisional Fmed estimates (Sissenwine and Shepherd 1987, Gabriel et al.
1989) averaged 0.20 (0.10 based on eggs/recruit, 0.16 based on spawning biomass/recruit, and 0.35 based on the extended series of spawners/recruit), which is similar to FMSY. However, survival ratios and estimates of Fmed may be underestimated, because partial selectivity of recruits to the survey was not accounted for.
As noted above, reference points based on SSB/R are problematic, as are extensions to MSY based metrics. The use of proxies (such as periods of stability) are being examined in the development of control rules (see SARC36 Working Paper C2 and Figure 20a). However, it is apparent that the choice of the stable period (and the stock status during that time) influence what becomes the M (maximum) of MSY based reference points. Additionally, if the stock has been reduced far enough below a sustainable level, there may need to be an extended period of time for recovery to allow any level of future stability. Further discussion on this point can be found in (see SARC36 Working Paper C3).
9.0 Recommendations and Findings 9.1 Evaluation of current status Size composition data from both the fishery and summer surveys indicate that good landings have followed the recruitment of strong (dominant) year classes. Poor landings since 1997, as well as low biomass estimates, can be attributed in part to the below-average recruitment of the 1994, 1995, 1997, and 1998 year classes.
In 2003, the 1997 year class will have passed out of the fishery, and the very weak 1998 year class (assumed 5-year old females), moderate 1999 year class (assumed 4-year-old females), virtually absent 2000 year class (assumed 3-year-old males, transitionals, and early-maturing females), very strong 2001 year class (assumed 2-year-old males, transitionals, and early-maturing females), and unknown 2002 year class (juveniles) will remain.
Exploitable biomass as estimated from CSA declined from 15,500 mt in 1995 to a time series low of 5,700 in 1999. Since then the biomass estimate has risen to 9,200 mt in 2002, as a result of the appearance of the moderate 1999 year class and the strong 2001 year class. This estimate is still well below the time-series average of 13,000 mt, and below the average of the 1985-1995 period of 17,000 mt (Table 8a). The estimate of spawning stock biomass (Figure 22a, arrow 36th SAW Consensus Summary 333
labeled 03) is also still well below the time-series mean.
9.2 Research Recommendations
- The potential for improving estimates of mortality, abundance, and biomass from historical fishery and survey data from the 1960s should be investigated for further guidance on appropriate biological reference points.
- Development of a time series of standardized effort would help to corroborate patterns of estimated F. Such analyses depend on completion of audits, processing of vessel logbook data, and estimation of data not included in logbooks (Maine small vessel fleet before 2000).
- Methods for age determination from length and ontogenetic stage information should be investigated to develop the possibility of using age-based assessment methods.
- A standard set of non-random stations have been sampled during the northern shrimp survey since 1994. When an adequate time series is achieved, catch data from these stations should be incorporated into survey indices of abundance and biomass.
- Estimates of fecundity at length should be updated, and the potential for annual variability should be explored.
- NEFSC fall trawl survey data should be segregated by day/night and analyzed for differences.
- The appropriate weighting of port sample data for estimates of mean weight should be investigated.
- Growth, survival, sex transition, fecundity, and migration in response to environmental conditions and population density should be evaluated.
- A better understanding of juvenile life history is needed.
- The implications of low male abundance should be investigated.
- Models that incorporate environmental variables and changes in life history parameters would be especially useful, if those signals are ever characterized better than they are currently.
ACKNOWLEDGMENTS The Northern Shrimp Technical Committee thanks all those people who have contributed to this assessment through their time and efforts as past Technical Committee members, scientific and vessel crew on the shrimp survey, port samplers, sample processors, data entry personnel, and data processors. In particular, we would like to thank the 1997-98 technical committee - Steven Cadrin, Daniel Schick, David McCarron, Stephen Clark, Michael Armstrong, Bruce Smith, and J. Brian OGorman. Much of the work presented here was developed by them (Cadrin et al, 1998).
334 36th SAW Consensus Summary
10.0 SARC Comments The CSA-estimated biomass of 9,200 mt is above the proposed biomass threshold of 9,000 mt, i.e. 50% of BMSY. However, management advice based on the results of biomass dynamics models may not provide sufficient detail relative to the unique life history characteristics of the species. The SARC questioned the usefulness of a single reference point estimate when simple interpretation of empirical data (fishery-independent indices) may provide more reliable management advice. Progress was made in assessing stock status with models, but further work to develop objective decision criteria is needed.
The SARC was concerned that the natural mortality estimate (M = 0.25) used in the CSA approach is uncharacteristically low for a short-lived shrimp species. It was noted that the regression method estimate of M = 0.25 and the Z-based estimate of M = 0.17 derived when the fishery was closed in 1978 are less than or equal to the value currently being used. The calculated Z in 2002, a year of minimal fishing effort, is 0.25. The SARC suggested investigating alternative methods of estimating M, such as maximum expected lifespan, size-dependent mortality, life-history based approaches, and deriving Z from the ratio of female 2 to females 1 and female 2 in the previous year.
Although biomass estimates from the current assessment do not match historical estimates, this discrepancy was attributable to changes in empirical data, including correction of the 1987 summer trawl survey indices, and updating of the time series of catch data. Revisions were also made to partitioning of recruits and fully recruited shrimp. The SARC recommended that any changes made since SARC 25 need to be documented.
The SARC discussed the appropriateness of the method of determining F from the CSA harvest rate. The F generated by this method is a more precise approximation than the log-ratio method.
10.1 Sources of Uncertainty
! Natural mortality is poorly defined.
! Catch reporting is often late and incomplete.
! Northern shrimp are not consistently available to the NEFSC Autumn survey because of:
a.) diurnal variation b.) migration patterns c.) egg-bearing females may have a more limited vertical migration pattern
! Growth, upon which YPR and EPR are based, is poorly estimated.
10.2 SARC Research Recommendations
! Further exploration of natural mortality assumption.
! Investigation of growth for improved calculation of YPR and SPR.
! Consider alternative estimators of F.
36th SAW Consensus Summary 335
! Consider a two- rather than a one-stage control rule.
! Investigate survey selectivity.
! Explore alternative assessment models especially, statistical catch-at-length methods.
! Consider the potential for using length-frequency distributions for developing management advice.
! Explore utilizing the ratio of stage 2 to stage 1 females for estimating total mortality.
! Investigate the appropriate weighting of port sample data for estimates of mean weight.
11.0 Literature Cited Abramson, N. 1980. Current stock assessment panel. In Proceedings of the International Pandalid Shrimp Symposium. Univ. Alaska Sea Grant Rep. 81-3: 259-275.
Anthony, V.C. and S.H. Clark. 1980. A description of the northern shrimp fishery and its decline in relation to water temperature. In Climate and Fisheries: proceedings from a workshop on the influence of environmental factors on fisheries production. URI Pub. p.119-121.
Apollonio, S., and E. E. Dunton, Jr. 1969. The northern shrimp, Pandalus borealis, in the Gulf of Maine. Completion Rept., ME Dept. Sea and Shore Fisheries, Proj. 3-12-R, 81 p.
Apollonio, S, D.K. Stevenson, and E.E. Dunton, Jr. 1984. Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine. Maine DMR Res. Ref.
Doc. 83/30.
Blott, A.J., P.J. Diodati, S.H. Clark, D.B. Sampson, and D.F. Schick. 1983. Development of a new research trawl for northern shrimp, Pandalus borealis, in the Gulf of Maine. ICES CM B:21.
Cadrin, S.X. and S.H. Clark. 1999. Application of Catch-Survey Models to the Northern Shrimp Fishery in the Gulf of Maine. N. Amer. J. of Fisheries Management 19:551-568.
Cadrin, S.X., D.F. Schick, D. McCarron, S.H. Clark, M.P. Armstrong, B. Smith, and J.B.
OGorman. 1998. Gulf of Maine Northern Shrimp Stock Assessment. NEFSC Ref. Doc.
98.07.
Charnov, E.L., D. Gotshchall, and J. Robinson. 1978. Sex ratio: adaptive response to population fluctuations in pandalid shrimp. Science 200: 204-206.
Clark, S.H. 1981. Recent trends in the Gulf of Maine northern shrimp fishery. NAFO SCR Doc.
81/XI/148.
Clark, S.H. 1982. Assessment and management of the Gulf of Maine northern shrimp (Pandalus borealis) fishery. ICES CM K:13.
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Clark, S.H. 1989. State-federal northern shrimp survey. ASMFC Spec. Rep. 17: 27-29.
Clark, S.H. and S. X. Cadrin. 2000. The Gulf of Maine Northern Shrimp (Pandalus borealis)
Fishery: a Review of the Record. J. Northw. Atl. Fish. Sci. 27: 193-226.
Clark, S.H. and V.C. Anthony. 1980. An assessment of the Gulf of Maine northern shrimp resource. In Proceedings of the International Pandalid Shrimp Symposium. Univ. Alaska Sea Grant Rep. 81-3: 207-224.
Collie, J.S. and G.H. Kruse. 1998. Estimating king crab (Paralithodes camtschaticus) abundance from commercial catch and research survey data. In: Proceedings of the North Pacific Symposium on Invertebrate Stock Assessment and Management. Edited by G.S. Jamieson and A. Cambell. Can. Spec. Publ. Fish. Aquat. Sci. 125. pp. 73-83.
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338 36th SAW Consensus Summary
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36th SAW Consensus Summary 339
Table C1a. Commercial landings (metric tons) of northern shrimp in the Gulf of Maine.
Year Maine Massachusetts New Hampshire Total $/Lb 1958 2.3 0.0 0.0 2.3 0.32 1959 5.4 2.3 0.0 7.7 0.29 1960 40.4 0.5 0.0 40.9 0.23 1961 30.4 0.5 0.0 30.9 0.20 1962 159.7 16.3 0.0 176.0 0.15 1963 244.0 10.4 0.0 254.4 0.12 1964 419.4 3.1 0.0 422.5 0.12 1965 947.0 8.0 0.0 955.0 0.12 1966 1,737.8 10.5 18.1 1,766.4 0.14 1967 3,141.1 10.0 20.0 3,171.1 0.12 1968 6,515.0 51.9 43.1 6,610.0 0.11 1969 10,992.9 1,772.9 58.1 12,823.9 0.12 1970 7,712.8 2,902.1 54.4 10,669.3 0.20 1971 8,354.7 2,723.8 50.8 11,129.3 0.19 1972 7,515.6 3,504.5 74.8 11,094.9 0.19 1973 5,476.7 3,868.2 59.9 9,404.8 0.27 1974 4,430.7 3,477.3 36.7 7,944.7 0.32 1975 3,177.0 2,080.2 29.5 5,286.7 0.26 1976 617.2 397.8 7.3 1,022.3 0.34 1977 148.0 236.9 2.3 387.2 0.55 1978 0.0 0.0 0.0 0.0 0.24 1979 32.9 451.3 2.3 486.5 0.33 1980 71.4 260.3 7.4 339.1 0.65 1981 528.6 538.1 4.5 1,071.2 0.64 1982 883.2 *(853.3) 658.5 *(655.3) 32.8 *(21.6) 1,574.5 *(1,530.2) 0.60 1983 1,022.0 (892.5) 508.0 (458.4) 36.5 (46.2) 1,566.5 (1,397.1) 0.67 1984 2,564.7 (2,394.9) 565.3 (525.1) 96.8 (30.7) 3,226.8 (2,950.7) 0.49 1985 2,956.9 (2,946.4) 1,030.6 (968.0) 207.4 (216.5) 4,194.9 (4,130.9) 0.44 1986 3,407.3 (3,268.2) 1,085.6 (1,136.3) 191.1 (230.5) 4,684.0 (4,635.0) 0.63 1987 3,534.2 (3,673.2) 1,338.7 (1,422.2) 152.5 (157.8) 5,025.4 (5,253.2) 1.10 1988 2,272.4 (2,257.2) 631.5 (619.6) 173.1 (154.5) 3,077.0 (3,031.3) 1.10 1989 2,542.6 (2,384.0) 749.6 (699.9) 314.3 (231.5) 3,606.5 (3,315.4) 0.98 1990 2,961.5 (3,236.1) 993.2 (974.3) 447.3 (451.2) 4,402.0 (4,661.6) 0.72 1991 2,431.1 (2,488.1) 727.6 (801.1) 208.2 (282.2) 3,366.9 (3,571.4) 0.93 1992 2,973.9 (3,054.1) 291.6 (289.1) 100.1 (100.0) 3,365.6 (3,443.6) 0.99 1993 1,562.8 (1,492.2) 300.3 (292.8) 441.1 (357.4) 2,304.7 (2,142.9) 1.03 1994 2,815.5 (2,239.3) 374.4 (247.5) 520.9 (428.0) 3,710.8 (2,914.8) 0.79 1995 (5,022.7) (678.8) (764.9) (6,466.4) 0.88 1996 (7,737.0) (658.0) (771.0) (9,166.1) 0.72 1997 (6,050.0) (362.8) (666.3) (7,079.1) 0.82 1998 (3482.0) (247.2) (445.2) (4,174.4) 0.94 1999 (1523.4) (75.7) (217.0) (1,816.1) 0.93 2000 (2067.3) (109.9) (212.3) (2,389.5) 0.79 2001 **(1071.8) **(49.1) **(205.8) **(1326.7) 0.90 2002 **(322.1) **(5.8) **(47.2) **(375.0)
- Numbers in parentheses are computed on a seasonal basis.
- Preliminary.
340 36th SAW Consensus Summary
Table C1b. Distribution of landings (metric tons) in the Gulf of Maine northern shrimp fishery by state and month.
Season Season Dec Jan Feb Mar Apr May Other Total Dec Jan Feb Mar Apr May Other Total 1986 Season, 203 days, Dec 1 - May 31, extended to June 21 1995 Season, 128 days, Dec 1 - Apr 30, 1 day per week off Maine 346.9 747.8 1,405.3 415.4 104.2 149.2 99.4 3,268.2 Maine 747.6 1,397.7 1,338.2 912.0 627.2 5,022.7 Mass. 154.3 213.4 221.2 200.7 111.2 84.8 150.7 1,136.3 Mass. 210.7 154.0 104.1 111.0 99.0 678.8 N.H. 57.7 75.9 70.8 14.2 1.3 0.0 10.6 230.5 N.H. 160.6 186.8 118.3 158.5 140.7 764.9 Total 558.9 1,037.1 1,697.3 630.3 216.7 234.0 260.7 4,635.0 Total 1,118.9 1,738.5 1,560.6 1,181.5 866.9 6,466.4 1987 Season, 182 days, Dec 1 - May 31 1996 Season, 152 days, Dec 1- May 31, 1 day per week off Maine 485.9 906.2 1,192.7 672.9 287.6 127.9 7.0 3,680.2 Maine 1,124.1 1,678.3 3,004.6 785.2 350.4 794.5 7,737.1 Mass. 103.5 260.0 384.9 310.2 180.8 182.8 5.7 1,427.9 Mass. 167.9 106.7 188.7 67.8 66.5 60.3 657.9 N.H. 18.4 53.6 62.8 15.7 7.3 0.0 0.1 157.9 N.H. 189.8 169.5 234.0 81.9 78.8 17.1 771.1 Total 607.8 1,219.8 1,640.4 998.8 475.7 310.7 12.8 5,266.0 Total 1,481.8 1,954.5 3,427.3 934.9 495.7 871.9 9,166.1 1988 Season, 183 days, Dec 1 - May 31 1997 Season, 156 days, Dec 1- May 27, two 5-day and four 4-day blocks off Maine 339.7 793.9 788.1 243.6 24.6 67.3 1.2 2,258.4 Maine 1,178.5 1,114.9 1,713.1 758.4 754.8 530.3 6,050.0 Mass. 14.4 225.8 255.0 104.9 8.6 10.9 0.0 619.6 Mass. 90.2 110.4 111.4 49.0 1.2 0.5 362.7 N.H. 13.0 72.6 53.7 14.9 0.3 0.0 3.1 157.6 N.H. 185.6 104.1 140.1 108.6 85.8 42.2 666.4 Total 367.1 1,092.3 1,096.8 363.4 33.5 78.2 4.3 3,035.6 Total 1,454.3 1,329.4 1,964.6 916.0 841.8 573.0 7,079.1 1989 Season, 182 days, Dec 1 - May 31 1998 Season, 105 days, Dec 8-May 22, weekends off except Mar 14-15, Dec 25-31 and Mar 16-31 off.
Maine 353.6 770.5 700.6 246.4 218.7 94.2 2,384.0 Maine 511.1 926.8 1,211.1 401.7 228.7 202.6 3,482.0 Mass. 26.2 197.5 154.9 104.8 160.9 55.6 699.9 Mass. 49.1 78.0 90.5 14.3 15.3 0.0 247.2 N.H. 28.5 106.9 77.0 15.4 3.7 0.0 231.5 N.H. 89.4 106.9 143.5 54.3 49.0 2.1 445.2 Total 408.3 1,074.9 932.5 366.6 383.3 149.8 3,315.4 Total 649.6 1,111.7 1,445.1 470.3 293.0 204.7 4,174.4 1990 Season, 182 days, Dec 1 - May 31 1999 Season, 90 days, Dec 15 - May 25, weekends, Dec 24 - Jan 3, Jan 27-31, Feb 24-28, Mar 16-31, and Apr 29 - May 2 off.
Maine 512.4 778.2 509.7 638.5 514.0 282.8 0.1 3,235.7 Maine 79.9 192.7 590.8 240.6 204.5 214.9 1,523.4 Mass. 75.6 344.4 184.8 100.2 158.9 110.0 4.3 978.2 Mass. 25.0 23.8 16.0 2.5 8.4 75.7 N.H. 111.3 191.7 116.1 30.7 1.4 451.2 N.H. 46.5 63.2 52.2 10.0 36.5 8.6 217.0 Total 699.3 1,314.3 810.6 769.4 674.3 392.8 4.4 4,665.1 Total 151.4 279.7 659.0 253.1 249.4 223.5 1,816.1 1991 Season, 182 days, Dec 1 - May 31 2000 Season, 51 days, Jan 17 - Mar 15, Sundays off Maine 238.2 509.1 884.0 454.9 251.7 148.2 2.0 2,488.1 Maine 607.4 1,271.4 188.5 2,067.3 Mass. 90.5 174.7 175.9 131.2 93.3 133.8 1.6 801.0 Mass. 17.4 78.7 13.8 109.9 N.H. 107.3 104.4 33.8 27.8 7.8 1.0 282.1 N.H. 39.6 131.1 41.6 212.3 Total 436.0 788.2 1,093.7 613.9 352.8 283.0 3.6 3,571.2 Total 664.4 1,481.2 243.9 2,389.5 1992 Season, 153 days, Dec 15 - May 15 *2001 Season, 83 days, Jan 9 - Apr 30, Mar 18 - Apr 16 off, experimental offshore fishery in May Maine 181.1 880.9 1,278.9 462.5 163.6 87.2 3,054.2 Maine 573.0 436.1 35.9 26.5 0.3 1,071.8 Mass. 17.1 148.2 73.3 47.5 2.9 0.1 289.1 Mass. 38.5 8.8 1.9 0.0 0 49.1 N.H. 33.4 47.0 11.9 6.8 1.0 100.1 N.H. 127.4 37.2 12.1 29.0 0 205.8 Total 231.6 1,076.1 1,364.1 516.8 167.5 87.2 0.4 3,443.7 Total 738.9 482.2 49.8 55.5 0.3 1,326.7 1993 Season, 138 days, Dec 14 - April 30 *2002 Season, 25 days, Feb 15 - Mar 11 Maine 100.9 369.0 597.0 297.5 127.8 1,492.2 Maine 253.6 68.5 322.1 Mass. 19.6 82.0 81.9 62.3 42.0 5.0 292.8 Mass. 3.7 2.1 5.8 N.H. 33.5 85.4 101.7 77.0 59.8 357.4 N.H. 35.6 11.6 47.2 Total 154.0 536.4 780.6 436.8 229.6 5.0 0.4 2,142.8 Total 292.8 82.2 375.0 1994 Season, 122 days, Dec 15 - Apr 15 Maine 171.5 647.7 971.9 399.5 48.7 2,239.3
- Preliminary data Mass. 27.1 68.0 100.8 38.8 12.8 247.5 N.H. 117.2 124.3 128.7 49.6 8.2 428.0 Total 315.8 840.0 1,201.4 487.9 69.7 2,914.8 36th SAW Consensus Summary 341
Table C2. Sample size (number of shrimp lengths measured) of Gulf of Maine northern shrimp port samples.
Fishing Season 1985-96 Month State 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 mean 2002 Dec ME 212 67 318 497 502 820 417 278 394 1149 904 505 MA 92 441 287 101 446 205 310 269 1611 1528 529 NH 602 884 370 639 761 760 306 331 541 560 389 559 Jan ME 326 519 849 825 1204 460 2191 2327 2136 1717 1498 2718 1,398 MA 1108 426 354 741 1137 819 642 789 903 1342 1231 863 NH 283 876 672 674 631 990 953 551 427 418 499 450 619 Feb ME 642 283 187 667 898 190 2816 2058 1915 2722 1420 4862 1,555 2618 MA 776 195 161 512 900 515 726 198 714 277 835 1709 627 573 NH 585 788 459 517 551 513 336 480 422 439 370 355 485 455 Mar ME 368 205 127 506 571 1407 1419 1570 1502 1572 944 3378 1,131 927 MA 830 388 414 149 232 358 652 1133 607 633 540 138 NH 91 298 499 75 639 508 97 375 550 598 392 375 532 Apr ME 38 58 303 1076 526 108 563 2789 2882 927 MA 647 236 245 81 313 103 377 1009 104 346 NH 107 362 186 218 May ME 751 1218 226 1031 287 5638 1,525 MA 429 75 1382 127 216 648 480 NH Jun ME MA 436 436 NH 438 438 Total 5997 6260 5603 6080 9352 8246 14611 10113 11557 11075 13978 27904 13554 3241 342 36th SAW Consensus Summary
Table C3. Sampling intensity (number of lengths per million landed) of Gulf of Maine northern shrimp port samples.
Fishing Season Month State 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 mean Dec ME 7.64 2.66 9.11 13.64 -- 9.60 44.14 35.76 32.42 24.94 18.66 11.10 19.06 MA 11.12 31.81 32.95 65.28 -- 52.99 25.41 -- 160.71 80.81 88.57 96.13 64.58 NH -- 128.06 569.24 313.23 292.63 72.31 86.60 102.54 85.04 28.01 25.96 19.59 156.66 Jan ME 4.93 10.22 12.72 15.95 19.75 7.33 55.47 38.06 61.70 30.24 14.16 20.38 24.24 MA 38.85 -- 16.42 23.38 34.63 28.57 42.70 51.82 83.54 108.72 76.62 122.53 57.07 NH 40.65 150.33 148.04 110.90 85.21 53.83 106.93 133.62 52.92 28.06 26.46 27.29 80.35 Feb ME 7.30 2.86 2.22 13.06 20.68 3.39 44.76 23.06 45.95 38.63 13.67 19.83 19.62 MA 35.42 10.67 5.95 28.55 36.86 30.84 30.98 32.37 86.69 29.05 72.24 112.38 42.67 NH 132.22 147.73 96.69 128.16 105.84 52.33 118.73 388.23 39.22 28.67 25.80 16.88 106.71 Mar ME 7.93 5.83 2.01 21.01 31.69 27.76 38.63 37.42 53.93 39.46 9.31 43.90 26.57 MA 37.90 21.47 14.73 18.97 -- 20.36 19.28 141.89 174.96 159.56 -- 107.30 65.13 NH 93.53 222.54 311.40 68.12 -- 200.26 217.01 150.15 39.88 96.50 31.96 41.47 133.89 Apr ME 3.03 6.13 -- -- 11.10 -- 44.35 35.42 10.40 104.25 35.23 75.31 32.52 MA 118.51 20.50 12.00 98.84 23.24 6.99 36.33 -- 198.57 107.81 -- -- 69.20 NH -- -- -- -- -- -- -- -- 13.63 -- 95.16 26.22 45.00 May ME -- -- -- 124.49 106.27 8.37 80.98 30.43 -- -- -- 67.16 69.61 MA -- 36.09 4.21 -- 217.45 11.09 9.94 -- -- -- -- 64.06 57.14 NH -- -- -- -- -- -- -- -- -- -- -- -- --
Jun ME -- -- -- -- -- -- -- -- -- -- -- -- --
MA -- 35.36 -- -- -- -- -- -- -- -- -- -- 35.36 NH -- 567.36 -- -- -- -- -- -- -- -- -- -- 567.36 Total 17.00 17.33 13.17 26.61 32.97 18.64 45.62 38.53 59.33 40.96 23.14 34.91 35.78 36th SAW Consensus Summary 343
Table C4. Mean weight (g) of Gulf of Maine northern shrimp from port samples.
Fishing Season Month State 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 mean Dec ME 12.120 13.761 13.913 9.327 9.798 12.825 15.531 11.756 12.142 13.793 12.497 MA 11.087 11.130 11.900 9.307 8.982 11.228 10.161 8.141 8.830 10.560 10.133 NH 12.276 11.849 11.009 13.042 10.578 12.223 11.189 8.598 6.071 9.759 9.555 10.559 Jan ME 12.881 14.734 13.568 15.340 12.639 12.401 12.887 14.406 10.658 11.409 13.214 12.582 13.060 MA 9.959 10.018 14.905 9.228 8.652 9.109 11.962 8.677 8.184 8.790 10.624 10.010 NH 12.395 13.024 11.815 11.944 14.439 10.425 11.718 11.396 10.591 8.349 9.905 10.278 11.357 Feb ME 12.456 14.185 14.161 15.421 16.134 9.086 14.050 14.324 14.328 13.793 12.886 12.256 13.590 MA 10.871 12.076 14.232 14.217 6.346 11.077 7.507 11.962 9.939 10.552 9.007 12.408 10.850 NH 11.383 13.265 13.219 13.322 14.781 11.850 11.927 9.627 9.456 8.412 8.247 11.133 11.385 Mar ME 11.323 11.836 10.651 10.113 13.678 12.596 12.387 11.021 10.684 10.029 8.992 10.204 11.126 MA 10.922 11.103 11.037 13.338 8.808 7.060 10.340 9.617 10.199 11.502 10.393 NH 11.923 10.600 9.790 13.533 9.629 11.886 10.526 8.190 8.704 8.468 8.654 10.173 Apr ME 9.321 11.010 8.020 10.376 11.011 12.318 9.021 8.058 9.157 9.810 MA 10.592 9.670 8.870 10.494 11.948 10.777 8.984 8.263 13.269 10.319 NH 7.617 7.989 11.111 8.905 May ME 11.156 8.215 10.469 11.637 9.241 9.465 10.031 MA 7.133 10.267 8.749 9.606 6.157 5.960 7.979 NH 9.005 Jun ME 12.973 MA 12.223 12.223 NH 13.723 13.723 mean 11.326 11.984 11.806 12.387 11.435 10.316 10.748 11.734 10.057 9.703 9.714 10.578 10.982 344 36th SAW Consensus Summary
Table C5. Observed northern shrimp discards from the shrimp trawl fishery and finfish trawl fisheries.
Shrimp Trawl Fishery Fishing Sampled lb lb Proportion Season Trips Kept Discarded Discarded 1985 1 2400 0 0.000 1986 3 4300 3 0.001 1987 4 3575 0 0.000 1988 9 18935 0 0.000 1989 17 23260 24 0.001 1990 17 22004 0 0.000 1991 37 66936 159 0.002 1992 57 67433 56 0.001 1993 80 91636 32 0.000 1994 80 101625 795 0.008 1995 57 77346 20 0.000 1996 31 49362.5 0 0.000 average 0.001 Large-mesh Fish Trawl Fishery Small-mesh Fish Trawl Fishery Sampled lb Discard/ Discard/ Sampled lb Discard/ Discard/
Year Trips Discard Trip (lb) Trip (mt) Trips Discard Trip (lb) Trip (mt) 1989 63 5 0.08 0.000 32 30 0.94 0.000 1990 36 1 0.03 0.000 16 0 0.00 0.000 1991 71 35 0.49 0.000 38 43 1.13 0.001 1992 56 5 0.09 0.000 28 11 0.39 0.000 1993 25 9 0.36 0.000 17 0 0.00 0.000 1994 15 0 0.00 0.000 4 0 0.00 0.000 1995 43 22 0.51 0.000 37 1,084 29.30 0.013 1996 22 0 0.00 0.000 47 5,355 113.94 0.052 1997 10 0 0.01 0.000 34 33 0.96 0.000 average 9 0.17 0.000 728 16.30 0.007 36th SAW Consensus Summary 345
Table C6. Distribution of fishing effort (number of trawl trips) in the Gulf of Maine northern shrimp fishery by state and month.
Season Season Dec Jan Feb Mar Apr May Other Total Dec Jan Feb Mar Apr May Other Total 1986 Season, 203 days, Dec 1 - May 31, extended to June 21 1995 Season, 128 days, Dec 1 - Apr 30, 1 day per week off Maine 590.0 1,309.0 2,798.0 831.0 224.0 133.0 68.0 5,953.0 Maine 879.0 2,341.0 2,641.0 1,337.0 694.0 7,892.0 Mass. 128.0 235.0 225.0 320.0 194.0 133.0 159.0 1,394.0 Mass. 145.0 385.0 275.0 157.0 109.0 1,071.0 N.H. 156.0 163.0 165.0 51.0 3.0 17.0 555.0 N.H. 189.0 331.0 279.0 359.0 344.0 1,502.0 Total 874.0 1,707.0 3,188.0 1,202.0 421.0 266.0 244.0 7,902.0 Total 1,213.0 3,057.0 3,195.0 1,853.0 1,147.0 10,465.0 1987 Season, 182 days, Dec 1 - May 31 1996 Season, 152 days, Dec 1- May 31, 1 day per week off Maine 993.0 2,373.0 3,073.0 2,241.0 617.0 340.0 16.0 9,653.0 Maine 1,341.0 2,030.0 3,190.0 1,461.0 444.0 457.0 8,923.0 Mass. 325.0 354.0 414.0 426.0 283.0 317.0 164.0 2,283.0 Mass. 299.0 248.0 325.0 269.0 106.0 126.0 1,373.0 N.H. 67.0 164.0 175.0 95.0 28.0 32.0 561.0 N.H. 331.0 311.0 389.0 248.0 155.0 61.0 1,495.0 Total 1,385.0 2,891.0 3,662.0 2,762.0 928.0 657.0 12,285.0 Total 1,971.0 2,589.0 3,904.0 1,978.0 705.0 644.0 11,791.0 1988 Season, 183 days, Dec 1 - May 31 1997 Season, 156 days, Dec 1- May 27, two 5-day and four 4-day blocks off Maine 972.0 2,183.0 2,720.0 1,231.0 193.0 122.0 7,421.0 Maine 1,674.0 1,753.0 2,737.0 1,178.0 793.0 530.0 8,665.0 Mass. 28.0 326.0 426.0 315.0 26.0 57.0 1,178.0 Mass. 184.0 226.0 245.0 114.0 7.0 1.0 777.0 N.H. 72.0 231.0 236.0 99.0 3.0 641.0 N.H. 277.0 245.0 301.0 218.0 189.0 62.0 1,292.0 Total 1,072.0 2,740.0 3,382.0 1,645.0 222.0 179.0 9,240.0 Total 2,135.0 2,224.0 3,283.0 1,510.0 989.0 593.0 10,734.0 1989 Season, 182 days, Dec 1 - May 31 1998 Season, 105 days, Dec 8-May 22, weekends off except Mar 14-15, Dec 25-31 and Mar 16-31 off.
Maine 958.0 2,479.0 2,332.0 936.0 249.0 84.0 7,038.0 Maine 852.0 1,548.0 1,653.0 725.0 346.0 189.0 5,313.0 Mass. 103.0 479.0 402.0 254.0 297.0 102.0 1,637.0 Mass. 94.0 200.0 148.0 70.0 3.0 1.0 515.0 N.H. 120.0 369.0 312.0 69.0 16.0 886.0 N.H. 141.0 216.0 182.0 134.0 83.0 22.0 778.0 Total 1,181.0 3,327.0 3,046.0 1,259.0 562.0 186.0 9,561.0 Total 1,086.0 1,964.0 1,983.0 929.0 432.0 212.0 6,606.0 1990 Season, 182 days, Dec 1 - May 31 1999 Season, 90 days, Dec 15 - May 25, weekends, Dec 24 - Jan 3, Jan 27-31, Feb 24-28, Mar 16-31, and Apr 29 - May 2 off.
Maine 1,036.0 1,710.0 1,529.0 1,986.0 897.0 238.0 7,396.0 Maine 190.0 556.0 1,125.0 553.0 324.0 172.0 2,920.0 Mass. 147.0 459.0 273.0 202.0 175.0 118.0 1,374.0 Mass. 39.0 57.0 71.0 9.0 40.0 216.0 N.H. 178.0 363.0 284.0 157.0 6.0 988.0 N.H. 82.0 192.0 213.0 44.0 123.0 21.0 675.0 Total 1,361.0 2,532.0 2,086.0 2,345.0 1,078.0 356.0 9,758.0 Total 311.0 805.0 1,409.0 606.0 487.0 193.0 3,811.0 1991 Season, 182 days, Dec 1 - May 31 2000 Season, 51 days, Jan 17 - Mar 15, Sundays off Maine 568.0 1,286.0 2,070.0 1,050.0 438.0 139.0 5,551.0 Maine 653.0 1,838.0 401.0 2,892.0 Mass. 264.0 416.0 401.0 231.0 154.0 147.0 1,613.0 Mass. 23.0 100.0 27.0 150.0 N.H. 279.0 285.0 135.0 82.0 22.0 1.0 804.0 N.H. 36.0 179.0 78.0 293.0 Total 1,111.0 1,987.0 2,606.0 1,363.0 614.0 287.0 7,968.0 Total 712.0 2,117.0 506.0 3,335.0 1992 Season, 153 days, Dec 15 - May 15 *2001 Season, 83 days, Jan 9 - Apr 30, Mar 18 - Apr 16 off, experimental offshore fishery in May Maine 411.0 1,966.0 2,700.0 1,222.0 318.0 141.0 6,758.0 Maine 1491.0 1209.0 112.0 39.0 6.0 2,857.0 Mass. 59.0 337.0 145.0 101.0 41.0 683.0 Mass. 111.0 46.0 10.0 1.0 168.0 N.H. 96.0 153.0 76.0 29.0 3.0 357.0 N.H. 302.0 142.0 27.0 31.0 502.0 Total 566.0 2,456.0 2,921.0 1,352.0 362.0 141.0 7,798.0 Total 1904.0 1397.0 149.0 71.0 6.0 3,527.0 1993 Season, 138 days, Dec 14 - April 30 *2002 Season, 25 days, Feb 15 - Mar 11 Maine 249.0 1,102.0 1,777.0 1,032.0 227.0 4,387.0 Maine 502.0 195.0 697.0 Mass. 60.0 200.0 250.0 185.0 72.0 767.0 Mass. 13.0 8.0 21.0 N.H. 76.0 246.0 275.0 256.0 151.0 1,004.0 N.H. 108.0 44.0 152.0 Total 385.0 1,548.0 2,302.0 1,473.0 450.0 6,158.0 Total 623.0 247.0 870.0 1994 Season, 122 days, Dec 15 - Apr 15 Maine 265.0 1,340.0 1,889.0 1,065.0 122.0 4,681.0
- Preliminary data Mass. 58.0 152.0 147.0 83.0 15.0 455.0 N.H. 169.0 228.0 266.0 173.0 18.0 854.0 Total 492.0 1,720.0 2,302.0 1,321.0 155.0 5,990.0 346 36th SAW Consensus Summary
Table C7.Stratified mean numbers and weights, per tow,* of northern shrimp collected during R/V Gloria Michelle summer surveys.
Untransformed Weight**
Total Age-1.5 >22 mm** Weight >22 mm Year Number Number Number (kg) (kg) 1984 3,005 48 826 22.6 8.9 1985 3,531 643 2,262 29.4 22.3 1986 3,327 703 1,688 29.7 19.6 1987 2,441 545 1,360 21.0 15.2 1988 4,310 2,812 1,012 26.6 11.7 1989 3,580 525 1,072 27.3 11.5 1990 3,021 264 2,097 29.4 22.2 1991 1,992 765 1,042 18.2 12.6 1992 1,503 443 625 12.9 7.6 1993 3,569 2,334 772 17.9 8.5 1994 3,435 1,285 849 21.1 9.3 1995 2,856 576 1,238 21.1 13.8 1996 2,651 793 1,223 20.2 13.8 1997 3,161 1,551 1,017 19.8 11.6 1998 2,319 533 676 15.1 7.4 1999 1,648 471 719 11.9 7.8 2000 1,843 997 647 11.9 7.2 2001 870 69 281 6.5 2.9 2002 3,157 2,313 571 15.0 6.3 Loge Transformed Weight**
Total Age-1.5 >22 mm** Weight >22 mm Year Number Number Number (kg) (kg) 1984 1,152 18 316 10.5 3.4 1985 1,849 337 1,184 17.7 11.7 1986 1,695 358 860 19.6 10.0 1987 1,385 342 854 14.8 9.5 1988 1,269 828 298 12.8 3.4 1989 1,883 276 564 17.0 6.1 1990 1,624 142 1,127 18.1 12.0 1991 1,255 482 657 11.7 8.0 1992 955 282 397 9.4 4.8 1993 1,156 757 250 9.1 2.8 1994 984 368 243 8.7 2.7 1995 1,449 292 628 13.3 7.0 1996 776 232 358 8.8 4.0 1997 762 374 245 7.7 2.8 1998 583 134 170 6.3 1.9 1999 398 114 174 5.8 1.9 2000 807 437 283 6.4 3.2 2001 451 36 146 4.3 1.5 2002 1,446 1,059 261 9.2 2.9
- Based on strata 1, 3, 5, 6, 7 and 8. **Will be fully recruited to the winter fishery.
36th SAW Consensus Summary 347
Table C8a. Summary of results from Collie-Sissenwine analysis of Gulf of Maine shrimp.
New Fully-Fishing Recruits Recruited Biomass Season (millions) (millions) F (NR+FR) (mt) 1985 987 947 0.09 14,051 1986 1,179 1,370 0.28 21,719 1987 985 1,498 0.40 22,499 1988 757 1,299 0.48 18,799 1989 1,177 987 0.18 14,220 1990 1,313 1,403 0.33 20,637 1991 829 1,519 0.44 22,190 1992 608 1,177 0.46 16,962 1993 512 881 0.42 12,396 1994 711 713 0.32 9,199 1995 975 809 0.33 12,378 1996 883 1,003 0.65 15,516 1997 534 764 0.87 11,008 1998 510 425 0.62 6,728 1999 408 391 0.46 5,791 2000 303 393 0.28 5,658 2001 445 409 0.40 6,238 2002 358 448 -0.01 6,110 2003 1,001 634 9,244 1985-1995 average 912 1,146 0.34 16,823 2000-2003 average 527 471 0.22 6,812 348 36th SAW Consensus Summary
Table C8b. Summary of input and output from Collie-Sissenwine analysis of Gulf of Maine shrimp.
Northern Shrimp Indices of Abundance Total using Summer Survey Survey Catch Year* Recuits Full Recruits Millions 1984 447.5580 479.0570 352.7928 1985 619.4560 925.4300 361.1710 1986 533.2920 848.5440 425.2945 1987 482.8980 766.9030 228.4345 1988 459.7550 387.7140 283.6468 1989 701.0930 817.9000 442.4292 1990 511.5210 907.5220 320.2898 1991 374.2770 612.0870 262.4338 1992 313.5950 444.3580 194.7883 1993 410.1960 320.7500 270.4058 1994 368.5900 364.3020 615.3185 1995 485.7860 653.3320 799.3678 1996 257.6520 348.6160 718.4332 1997 257.2980 267.1010 373.6801 1998 217.1340 226.6420 215.1221
- Survey Year Data are applied to 1999 137.3900 174.6070 209.2793 the following Fishing Year 2000 276.2810 288.1930 141.4937 2001 171.8090 196.3560 38.6779 2002 550.6000 372.9300 Input File Name R2002.dat Tuning Dataset Survey Time of Survey (yr) 0 Time of Catch (yr) 0.5 Natural Mortality Rate 0.25 Relative Catchability: Recruits to Full Recruits s_r 0.7 - 1.0 Catchability Estimate and CV 0.550 0.16 Average Partial Recruitment Rate to Fishery 0.63 Average Z_all sizes (1999-2001) 0.59 Average Z_all sizes (2000-2001) 0.44 Stock Size Estimates Total Fishing Survey millions at time of Survey Mortality Mortality Year* Recruits Full Recruits Z all sizes All Sizes 1984 986.8 947.3 0.34 0.09 1985 1179.3 1369.9 0.53 0.28 1986 984.7 1497.6 0.65 0.40 Note that the recruit abundance index for the 1987 757.5 1298.8 0.73 0.48 last year is NOT used in the least squares estimation. 1988 1176.6 987.2 0.43 0.18 It is, however, used in conjunction with the least 1989 1313.2 1402.9 0.58 0.33 squares estimate of q_n and the selectivity of the 1990 829.4 1519.4 0.69 0.44 recruits to calculate recruit population size in 2001 1991 608.2 1177.1 0.71 0.46 1992 511.5 881.3 0.67 0.42 1993 711.4 712.6 0.57 0.32 1994 975.1 808.6 0.58 0.33 1995 883.4 1002.7 0.90 0.65 1996 534.0 764.1 1.12 0.87
- Survey Year Data are applied to 1997 510.5 424.6 0.87 0.62 the following Fishing Year 1998 408.2 391.5 0.71 0.46 1999 303.4 392.8 0.53 0.28 2000 445.1 409.4 0.65 0.40 2001 357.9 447.9 0.24 -0.01 2002 1000.6 634.2 Total Catch (millions) Est. Abundance & Total Mortality Rate Z 900 1600 1.2 800 1400 1.0 Abundance (millions) 700 1200 Catch (millions) 600 0.8 1000 Z (all sizes) 500 800 0.6 400 600 300 0.4 400 200 0.2 100 200 Recruits Full Recruits Z all sizes 0 0 0.0 1984 1988 1992 1996 2000 1984 1988 1992 1996 2000 Survey Year Survey Year 36th SAW Consensus Summary 349
Table C9. Summary of CSA retrospective analyses.
Retrospective CSA Runs BL 1984 - 2001 R1 1985 - 2001 R2 1986 - 2001 R3 1987 - 2001 R4 1988 - 2001 R5 1989 - 2001 R6 1984 - 2000 R7 1984 - 1999 R8 1984 - 1998 R9 1984 - 1997 R10 1984 - 1996 Fishing Mortality Year BL R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 1984 0.09 0.10 0.09 0.10 0.09 0.09 1985 0.28 0.31 0.28 0.28 0.28 0.28 0.28 1986 0.4 0.41 0.38 0.40 0.40 0.40 0.40 0.40 1987 0.48 0.18 0.18 0.17 0.13 0.18 0.18 0.18 0.18 0.18 1989 0.33 0.33 0.33 0.33 0.32 0.32 0.33 0.33 0.33 0.33 0.33 1990 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 1991 0.46 0.46 0.46 0.46 0.45 0.45 0.46 0.45 0.46 0.46 0.46 1992 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 1993 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 1994 0.33 0.33 0.33 0.32 0.32 0.32 0.33 0.32 0.33 0.32 0.32 1995 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.66 0.65 0.65 1996 0.87 0.88 0.87 0.86 0.85 0.85 0.87 0.85 0.89 0.85 0.85 1997 0.62 0.63 0.62 0.62 0.61 0.61 0.62 0.61 0.64 0.58 1998 0.46 0.46 0.46 0.46 0.46 0.46 0.46 0.44 0.52 1999 0.28 0.29 0.28 0.28 0.27 0.27 0.29 0.22 2000 0.40 0.40 0.40 0.39 0.39 0.39 0.41 2001 -0.01 -0.01 -0.01 -0.01 -0.01 -0.01 350 36th SAW Consensus Summary
Table C9 (cont.). Summary of CSA retrospective analyses Abundance of Recruits Year BL R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 1984 986.79 983.33 1010.69 963.94 1001.53 1003.43 1985 1179.3 1143.61 1175.02 1208.87 1151.03 1197.53 1199.89 1986 984.66 965.48 991.53 981.05 1009.6 960.82 1000.04 1002.02 1987 757.48 744.57 755.68 773.71 754.62 777.23 738.59 769.66 771.23 1988 1176.59 1157.57 1174.01 1199.77 1280.87 1172.38 1205.65 1148.81 1194.51 1196.83 1989 1313.15 1292.19 1309.04 1331.99 1373.48 1361.49 1308.42 1345.83 1281.92 1333.3 1335.9 1990 829.43 815.8 826.6 840.84 862.94 858.72 826.34 850.76 809.04 842.58 844.28 1991 608.2 598.24 606.12 616.47 632.24 629.44 605.95 623.79 593.29 617.82 619.06 1992 511.52 503.25 509.78 518.37 531.37 529.1 509.64 524.46 499.14 519.51 520.54 1993 711.37 701.04 709.2 719.93 736.18 733.36 709.02 727.56 695.9 721.4 722.7 1994 975.13 965.95 973.2 982.85 997.74 995.13 973.03 989.84 961.26 984.54 985.79 1995 883.44 876.04 881.88 889.69 901.82 899.7 881.74 895.48 871.96 891.88 893.06 1996 534.01 530.71 533.31 536.83 542.41 541.43 533.23 539.64 528.33 539.19 539.99 1997 510.46 505.01 509.31 515.02 523.78 522.25 509.12 520.3 497.9 526.4 529.21 1998 408.2 402.66 407.04 412.8 421.57 420.05 406.67 420.31 387.43 445.67 1999 303.41 299.43 302.58 306.73 313.03 311.94 301.9 317.48 270.35 2000 445.05 437.94 443.56 450.94 462.1 460.17 439.25 515.49 2001 357.93 352.02 356.69 362.81 372.06 370.46 345.59 2002 1000.64 983.57 997.06 1014.75 1041.45 1036.85 Abundance of Post-Recruits Year BL R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 1984 947.28 943.94 970.32 925.25 961.49 963.32 1985 1369.94 1503.03 1364.46 1407.76 1333.76 1393.26 1396.27 1986 1497.65 1512.24 1376.96 1491.6 1539.39 1457.72 1523.39 1526.72 1987 1298.84 1285.18 1264.24 1148.23 1293.37 1336.64 1262.68 1322.15 1325.16 1988 987.19 971.84 976.01 958.62 746.53 983.12 1015.31 960.28 1004.53 1006.77 1989 1402.9 1378.73 1395.6 1411.33 1383.83 1424.56 1397.25 1441.86 1365.62 1426.93 1430.03 1990 1519.36 1492.03 1513.07 1539.07 1565.46 1569.96 1513.13 1562.43 1478.17 1545.92 1549.35 1991 1177.07 1155.86 1172.49 1193.93 1223.27 1220.34 1172.25 1210.32 1145.26 1197.58 1200.23 1992 881.33 865.41 877.96 894.34 918.33 914.71 877.72 906.26 857.48 896.72 898.71 1993 712.55 700.08 709.93 722.83 742.12 738.93 709.73 732.08 693.86 724.63 726.19 1994 808.58 795.64 805.87 819.28 839.48 836.03 805.65 828.86 789.14 821.24 822.88 1995 1002.71 988.84 999.79 1014.24 1036.23 1032.43 999.55 1024.7 981.57 1017.18 1019.13 1996 764.06 754.71 762.1 771.88 786.87 784.27 761.91 779.23 748.98 775.97 777.7 1997 424.61 416.57 422.92 431.33 444.19 441.96 422.73 438.01 410.26 438.2 440.36 1998 391.46 383.69 389.83 397.93 410.25 408.12 389.52 406.03 371.42 420.06 1999 392.76 385.58 391.26 398.72 410.04 408.08 390.47 412.56 352.2 2000 409.36 401.18 407.64 416.14 428.98 426.77 405.07 454.33 2001 447.86 439.23 446.05 454.99 468.5 466.17 435.15 2002 634.18 622.73 631.78 643.65 661.58 658.49 36th SAW Consensus Summary 351
Table C9 (cont.). Summary of CSA retrospective analyses Biomass of Recruits Year BL R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 1984 6.31 6.29 6.47 6.17 6.41 6.42 1985 8.85 8.58 8.82 9.07 8.64 8.99 9.00 1986 7.07 6.93 7.12 7.04 7.25 6.90 7.18 7.19 1987 5.48 5.39 5.47 5.60 5.46 5.62 5.35 5.57 5.58 1988 5.74 5.65 5.73 5.85 6.25 5.72 5.88 5.61 5.83 5.84 1989 8.71 8.57 8.69 8.84 9.11 9.03 8.68 8.93 8.51 8.85 8.86 1990 6.84 6.73 6.82 6.93 7.11 7.08 6.81 7.01 6.67 6.95 6.96 1991 4.08 4.02 4.07 4.14 4.25 4.23 4.07 4.19 3.98 4.15 4.16 1992 3.36 3.31 3.35 3.41 3.49 3.48 3.35 3.45 3.28 3.42 3.42 1993 3.31 3.26 3.30 3.35 3.42 3.41 3.29 3.38 3.23 3.35 3.36 1994 5.68 5.62 5.67 5.72 5.81 5.79 5.67 5.76 5.60 5.73 5.74 1995 5.98 5.93 5.97 6.02 6.10 6.09 5.97 6.06 5.90 6.04 6.04 1996 3.51 3.49 3.50 3.53 3.56 3.56 3.50 3.55 3.47 3.54 3.55 1997 2.75 2.72 2.75 2.78 2.83 2.82 2.75 2.81 2.69 2.84 2.86 1998 2.46 2.43 2.46 2.49 2.54 2.53 2.45 2.54 2.34 2.69 1999 2.00 1.97 1.99 2.02 2.06 2.05 1.99 2.09 1.78 2000 2.44 2.40 2.43 2.47 2.53 2.52 2.40 2.82 2001 2.38 2.34 2.37 2.41 2.47 2.46 2.30 2002 4.48 4.41 4.47 4.55 4.67 4.65 Biomass of Post-Recruits Year BL R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 1984 7.74 7.71 7.92 7.56 7.85 7.87 1985 12.87 14.12 12.82 13.22 12.53 13.09 13.12 1986 15.43 15.58 14.19 15.37 15.86 15.02 15.69 15.73 1987 13.32 13.18 12.96 11.77 13.26 13.70 12.95 13.56 13.59 1988 8.48 8.35 8.38 8.23 6.41 8.44 8.72 8.25 8.63 8.65 1989 11.92 11.72 11.86 12.00 11.76 12.11 11.88 12.26 11.61 12.13 12.16 1990 15.35 15.08 15.29 15.55 15.82 15.86 15.29 15.79 14.94 15.62 15.65 1991 12.88 12.65 12.83 13.06 13.38 13.35 12.83 13.24 12.53 13.10 13.13 1992 9.03 8.87 9.00 9.17 9.41 9.38 9.00 9.29 8.79 9.19 9.21 1993 5.89 5.79 5.87 5.98 6.14 6.11 5.87 6.06 5.74 5.99 6.01 1994 6.70 6.59 6.68 6.79 6.96 6.93 6.68 6.87 6.54 6.81 6.82 1995 9.54 9.40 9.51 9.65 9.86 9.82 9.51 9.75 9.34 9.67 9.69 1996 7.50 7.41 7.48 7.58 7.72 7.70 7.48 7.65 7.35 7.62 7.63 1997 3.97 3.90 3.96 4.04 4.16 4.14 3.96 4.10 3.84 4.10 4.12 1998 3.33 3.26 3.31 3.38 3.49 3.47 3.31 3.45 3.16 3.57 1999 3.66 3.60 3.65 3.72 3.82 3.81 3.64 3.85 3.28 2000 3.80 3.73 3.79 3.87 3.98 3.96 3.76 4.22 2001 3.73 3.66 3.71 3.79 3.90 3.88 3.62 2002 4.76 4.67 4.74 4.83 4.96 4.94 352 36th SAW Consensus Summary
Table C10. Summary of biomass dynamics model input data, results, and parameter estimates.
Input Results Fishing Autumn Maine Summer Catch Biomass Season (mt) (mt) F Parameter Estimate 1968 1.8 45.8 5,708 46,330 0.126 B1969 45,750 1969 4.5 31.2 12,140 44,520 0.3 K (mt) 59,850 1970 3.1 40.8 11,330 36,960 0.337 r 0.3345 1971 3.5 9.4 10,590 30,750 0.38 q autumn 0.0915 1972 3.4 7.0 11,220 25,300 0.514 q Maine 0.4831 1973 5.1 7.8 9,691 18,860 0.614 q summer 0.6866 1974 10.0 4.9 8,024 13,160 0.773 1975 6.8 6.7 6,142 8,075 1.103 MSY 5,004 1976 2.3 4.8 1,387 3,660 0.392 Bmsy 29,920 1977 1.9 1.6 372 3,416 0.097 Fmsy 0.1672 1978 0.0 3.2 17 4,276 0.003 Ratio of B(2003) to Bmsy 0.4872 1979 1.0 4.4 487 5,838 0.074 Ratio of F(2002) to Fmsy 0.1722 1980 0.7 2.7 339 7,363 0.04 B2003 14,580 1981 0.7 3.0 1,071 9,505 0.103 F2002 0.029 1982 5.1 2.0 1,530 11,400 0.124 1983 1.4 4.2 1,397 13,230 0.097 1984 1.6 10.5 2,951 15,600 0.183 1985 2.6 17.7 4,131 16,710 0.247 1986 1.9 19.6 4,635 16,740 0.281 1987 3.1 15.4 5,253 16,220 0.338 1988 2.5 12.8 3,031 14,930 0.197 1989 1.8 17.0 3,315 15,840 0.204 1990 2.3 18.1 4,662 16,600 0.286 1991 3.8 11.7 3,571 16,030 0.219 1992 5.9 9.4 3,444 16,550 0.204 1993 1.3 9.1 2,143 17,290 0.116 1994 1.3 8.7 2,915 19,540 0.143 1995 3.6 13.3 6,466 21,270 0.318 1996 8.2 8.8 9,166 19,440 0.547 1997 5.3 7.7 7,154 14,420 0.576 1998 1.8 6.3 4,174 10,650 0.419 1999 0.7 5.8 1,816 9,334 0.185 2000 1.7 6.4 2,389 10,350 0.224 2001 2.1 4.3 1,327 10,970 0.111 2002 9.2 375 12,930 0.026 36th SAW Consensus Summary 353
Table C11. Yield and egg production per recruit of Gulf of Maine northern shrimp.
For an example fishing mortality F = 0.20, natural mortality M = 0.25, and 1,000 age 0 recruits.
Input Data Results Length Transition Fishery Male Female Fecundity Total Male Female Male Female Yield Egg Age (mm) Rate (% Fem) Selectivity wt (g) wt (g) at length N N N Catch Catch (g) Production 1 11.17 0 0.033 0.84 1.24 0 774 774 0 4 0 4 0 2 18.43 0 0.230 3.79 4.82 0 575 575 0 31 0 117 0 3 23.50 0.081 0.579 7.87 9.30 1,286 399 367 32 56 0 439 41,581 4 27.04 0.922 0.799 12.00 13.58 1,876 265 21 244 48 4 635 458,156 5 29.51 0.997 0.893 15.60 17.19 2,287 173 0 172 3 35 657 393,661 6 31.23 1.000 0.933 18.50 20.04 2,574 112 0 111 0 26 523 287,027 7 32.43 1.000 1.000 20.72 22.19 2,775 71 0 71 0 18 399 197,299 total 2,773 1,377,725 total/recruit 2.773 1,378
% of max 57.52 Ref. Point F YPR %EPR Count per pound Fmax 0.77 4.25 14.77 Age Male Female F0.1 0.46 3.99 29.83 1 540 366 Fexample 0.20 2.77 57.52 2 120 94 F50% 0.25 3.14 50 3 58 49 F40% 0.34 3.62 40 4 38 33 F30% 0.45 3.97 30 5 29 26 F20% 0.63 4.21 20 6 25 23 F10% 0.95 4.21 10 7 22 20 354 36th SAW Consensus Summary
14,000 Total 12,000 Maine 10,000 Massachusetts Landings in metric tons New Hampshire 8,000 6,000 4,000 2,000 0
1960 65 70 75 80 85 90 95 2000 Figure C1. Gulf of Maine northern shrimp landings by fishing season.
Figure C2. Distribution of monthly landings of Gulf of Maine northern shrimp, 1984 - 1996.
36th SAW Consensus Summary 355
male transitional female 1 ovigerous female 2 Landings (millions of shrimp) 50 1985 0
10 15 20 25 30 50 1986 0
10 15 20 25 30 50 1987 0
10 15 20 25 30 50 1988 0
10 15 20 25 30 50 1989 0
10 15 20 25 30 50 1990 0
10 15 20 25 30 Dorsal carapace length in mm.
Figure C3. Gulf of Maine northern shrimp landings by length, developmental stage, and fishing season.
356 36th SAW Consensus Summary
male transitional female 1 ovigerous female 2 Landings (millions of shrimp) 50 1991 0
10 15 20 25 30 50 1992 0
10 15 20 25 30 50 1993 0
10 15 20 25 30 50 1994 0
10 15 20 25 30 50 1995 0
10 15 20 25 30 50 1996 0
10 15 20 25 30 Dorsal carapace length in mm.
Figure C3 continued.
36th SAW Consensus Summary 357
male transitional female 1 ovigerous female 2 Landings (millions of shrimp) 50 1997 0
10 15 20 25 30 50 1998 0
10 15 20 25 30 50 1999 0
10 15 20 25 30 50 2000 0
10 15 20 25 30 50 2001 0
10 15 20 25 30 50 2002 0
10.0 15.0 20.0 25.0 30.0 Dorsal carapace length in mm.
Figure C3 continued.
358 36th SAW Consensus Summary
Maine Massachusetts and New Hampshire February February 254 mt 39 mt 14 14 12 Males 12 Percent Frequency Males Percent Frequency 3.0% 3.0%
10 10 Trans & Fem I Trans & Fem I 8 0.2% 8 9.9%
6 Female II 6 Female II 4 45.9% 4 65.3%
2 Ovigerous Ovigerous 2
50.9% 21.8%
0 0 March March 68 mt 14 mt 14 14 Males 12 Males 12 8.2%
Percent Frequency Percent Frequency 13.9%
10 10 Trans & Fem I Trans & Fem I 30.7%
8 4.5% 8 Female II 6 Female II 6 61.2%
76.3%
4 4 Ovigerous Ovigerous 0.0%
2 5.3% 2 0 0
<10.0 11.5 13.5 15.5 17.5 19.5 21.5 23.5 25.5 27.5 29.5 31.5 33.5 <10.0 11.5 13.5 15.5 17.5 19.5 21.5 23.5 25.5 27.5 29.5 31.5 33.5 Dorsal Carapace Length (mm) Dorsal Carapace Length (mm)
Figure C4a. Gulf of Maine northern shrimp landings by length, developmental stage, and month, 2002 fishing season.
36th SAW Consensus Summary 359
Figure C4b.Gulf of Maine northern shrimp landings by length, developmental stage, and month, 1996 fishing season.
360 36th SAW Consensus Summary
18 16 Total Trawl Trips (thousands) 14 12 10 8
6 4
2 0
1965 1970 1975 1980 1985 1990 1995 2000 1.4 140 mt/trip kg/hr 1.2 120 Landings (mt) per Trawl Trip Landings (mt) per Trawl Hour 1.0 100 0.8 80 0.6 60 0.4 40 0.2 20 0.0 0 1965 1970 1975 1980 1985 1990 1995 2000 Figure C5. Nominal fishing effort, and CPUE.
Above - trips from NMFS data.
Below - Catch per unit effort in landings per trip, and per hour from state interview data.
36th SAW Consensus Summary 361
50 12 45 10 Maine/Shrimp Survey (kg/tow) 40 Autumn Survey (kg/tow) 35 8
30 25 6 20 4
15 10 2
5 0 0 19 19 19 19 19 1968 70 72 74 76 78 19 19 19 19 19 1980 82 84 86 88 90 19 19 19 19 20 2092 94 96 98 00 02 Year Maine Survey Shrimp Survey Autumn Survey Figure C6. Research trawl survey indices of Gulf of Maine northern shrimp biomass (kg/tow).
362 36th SAW Consensus Summary
Figure C7. State of Maine summer survey fixed station locations.
36th SAW Consensus Summary 363
Figure C8. Northern shrimp survey strata and observed distribution of catch per tow (kg) collected during the NEFSC autumn bottom trawl survey in the western Gulf of Maine aboard the R/V Albatross IV, October 2001.
364 36th SAW Consensus Summary
Figure C9.Gulf of Maine northern shrimp summer survey strata and observed distribution of catch per tow (kg) collected during 2002 aboard the R/V Gloria Michelle, July 22 -
August 2, 2002.
36th SAW Consensus Summary 365
6000 Untransformed Ln transformed 5000 4000 Mean Number per tow 3000 2000 1000 0
1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 Year Figure C10. Gulf of Maine summer survey indices of abundance (mean number per tow +/- 2 SE).
366 36th SAW Consensus Summary
Number per Tow (thousands) Weight per Tow (kg) 4.0 5 25 35 30 4 20 Loge Transformed 25 Untransformed 3 15 20 15 2 10 10 1 5 5
0.0 0 0 0 1983 1988 1993 1998 2003 1983 1988 1993 1998 2003 Loge Transformed Untransformed Loge Transformed Untransformed Age-1.5 Number per Tow (thousands) >22mm Weight per Tow (kg) 1.2 3.0 14 25 1.0 2.5 12 20 Loge Transformed 10 0.8 2.0 Untransformed 15 8
0.6 1.5 6
10 0.4 1.0 4
0.2 0.5 5 2
0.0 0.0 0 0 1983 1988 1993 1998 2003 1983 1988 1993 1998 2003 Loge Transformed Untransformed Loge Transformed Untransformed Figure C11. Gulf of Maine northern shrimp summer survey indices of abundance.
36th SAW Consensus Summary 367
Mean Number per Males Female 1 Female 2 Tow 200 1984 100 83 0
10 15 20 25 30 200 100 84 1985 0
10 15 20 25 30 200 85 1986 100 0
10 15 20 25 30 200 1987 100 86 0
10 15 20 25 30 200 87 1988 100 0
10 15 20 25 30 200 88 1989 100 0
10 15 20 25 30 200 100 1990 89 0
10 15 20 25 30 Dorsal Carapace Length (mm)
Figure C12. Gulf of Maine northern shrimp summer survey mean catch per tow by length and developmental stage, by survey year. 2-digit numbers are assumed 1.5 age year class.
368 36th SAW Consensus Summary
Mean Number per Males Female 1 Female 2 Tow 200 90 1991 100 0
10 15 20 25 30 200 100 1992 91 0
10 15 20 25 30 200 92 1993 100 0
10 15 20 25 30 200 1994 100 93 0
10 15 20 25 30 200 1995 100 94 0
10 15 20 25 30 200 1996 100 95 0
10 15 20 25 30 200 100 96 1997 0
10 15 20 25 30 Dorsal Carapace Length (mm)
Figure C12 continued.
36th SAW Consensus Summary 369
Mean Number per Males Female 1 Female 2 Tow 200 1998 100 97 0
10 15 20 25 30 200 100 1999 98 0
10 15 20 25 30 200 99 2000 100 0
10 15 20 25 30 200 2001 100 00 0
10 15 20 25 30 01 200 2002 100 0
10 15 20 25 30 Dorsal Carapace Length (mm)
Figure C12 continued.
370 36th SAW Consensus Summary
Figure C13. The selectivity method of deriving indices of abundance for fully-recruited and recruited Gulf of Maine northern shrimp from summer survey length frequencies.
Example illustrated here is from 1996.
36th SAW Consensus Summary 371
1.4 F - Instantaneous Fishing 1.2 1.0 0.8 0.6 Mortality 0.4 0.2 0.0
-0.2 1984 1988 1992 1996 2000 2004 Fishing Year 3500 Total Abundance (millions) 3000 2500 2000 1500 1000 500 0
1984 1988 1992 1996 2000 2004 Fishing Year 30 Total Biomass (thousands of 25 20 15 10 mt) 5 0
1984 1988 1992 1996 2000 2004 Fishing Year Figure C14. Summary of CSA for Gulf of Maine northern shrimp with least squares estimates, bootstrapped means, and 80% confidence intervals.
372 36th SAW Consensus Summary
New Recruit Abundance 2000 1500 1000 (millions) 500 0
1984 1988 1992 1996 2000 2004 Fishing Year 2000 Full Recruit Abundance 1500 1000 (millions) 500 0
1984 1988 1992 1996 2000 2004 Fishing Year 12 New Recruit Biomass 10 8
6 (thousands of mt) 4 2
0 1984 1988 1992 1996 2000 2004 Fishing Year 20 Full Recruit Biomass 15 10 (thousands of mt) 5 0
1984 1988 1992 1996 2000 2004 Fishing Year Figure C14 continued.
36th SAW Consensus Summary 373
asdf 800 0.20 Recruitment Index (number/tow) 700 Observed 0.15 Estimated Residuals (pre-recruits) 600 0.10 500 0.05 400 0.00 300 -0.05 200 -0.10 100 -0.15 0 -0.20 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Survey Year Survey Year 1000 0.30 Fully Recruited Index (number/tow) 900 0.20 Residuals (fully recruited) 800 Observed 700 Estimated 0.10 600 0.00 500
-0.10 400 300 -0.20 200
-0.30 100
-0.40 0
1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Survey Year Survey Year 1000 0.4 900 Calculated 0.3 Ncalc Index (number/tow) 800 Estimated 700 Residuals (Ncalc) 0.2 600 500 0.1 400 0.0 300 200 -0.1 100 0 -0.2 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 Survey Year Survey Year Figure C15. Summary results of CSA of Gulf of Maine northern shrimp with residuals.
374 36th SAW Consensus Summary
0.16 1 Median = 0.04 0.14 80% CI = -0.12 to 0.21 0.8 0.12 Cumulative Probability 0.1 0.6 Probability 0.08 0.4 0.06 0.04 0.2 0.02 0 0
-0.35 -0.25 -0.15 -0.05 0.05 0.15 0.25 0.35 0.45 Fishing Mortality (F n+r ) 2001 Figure C16a. Bootstrapped CSA estimates of fishing mortality for the 2002 fishing season (2001 survey year) for Gulf of Maine northern shrimp.
Distribution of F Bootstrap Estimates 0.30 0.25 Median (using "Average ")= 0.25 Median (using full distribution) = 0.26 0.20 Probability 0.15 0.10 0.05 0.00
-0.325 -0.225 -0.125 -0.025 0.075 0.175 0.275 0.375 0.475 0.575 0.675 0.775 Fishing Mortality (Fn+r ) 1999-2001 Figure C16b. Bootstrapped CSA estimates of fishing mortality for the 2000-2002 fishing seasons (1999-2001 survey years) for Gulf of Maine northern shrimp.
36th SAW Consensus Summary 375
Distribution of F using Full Range of Bootstrap Estimates 0.12 Median = 0.26 1.0 80%CI = -0.03 to 0.48 0.1 0.8 Cumulative Probability 0.08 Probability 0.6 0.06 0.4 0.04 0.2 0.02 0 0.0
-0.325 -0.225 -0.125 -0.025 0.075 0.175 0.275 0.375 0.475 0.575 0.675 0.775 Fishing Mortality (Fn+r) 1999-2001 Distribution of F using Averages of 3 year Bootstrap Estimates 0.3 1 Median = 0.26 80%CI = -0.03 to 0.48 0.25 0.8 Cumulative Probability 0.2 Probability 0.6 0.15 0.4 0.1 0.2 0.05 0 0 0.025 0.075 0.125 0.175 0.225 0.275 0.325 0.375 0.425 0.475 0.525 Fishing Mortality (Fn+r) 1999-2001 Figure C16c. Bootstrapped CSA estimates of fishing mortality for the 2000-2002 fishing seasons (1999-2001 survey year) for Gulf of Maine northern shrimp using all 6000 bootstrap iterations, and three year averages of the 2000 iterations (see text).
376 36th SAW Consensus Summary
1.0 0.9 0.8 0.7 Fishing Mortality (F r+n) 0.6 0.5 0.4 0.3 0.2 0.1 0.0
-0.1 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 Ye ar Figure C17a. Retrospective CSA estimates of fishing mortality for Gulf of Maine northern shrimp.
1600 1400 1800 1200 1600 Abundance Estimate (R) 1400 Abundance Estimate (N) 1000 1200 800 1000 600 800 600 400 400 200 200 0
0 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 Year Year Figure C17b. Retrospective CSA estimates of abundance (recruits and fully recruited) for Gulf of Maine northern shrimp.
36th SAW Consensus Summary 377
10 18 9 16 8
14 7
12 Biomass Estimate (R) Biomass Estimate (N) 6 10 5
8 4
6 3
4 2
1 2 0 0 1980 1985 1990 1995 2000 2005 1980 1985 1990 1995 2000 2005 Year Year Figure C17c. Retrospective CSA estimates of biomass (recruits and fully recruited) for Gulf of Maine northern shrimp.
378 36th SAW Consensus Summary
NLS q 0.6 0.5 0.4 0.3 0.2 0.1 0
1984- 1985- 1986- 1987- 1988- 1989- 1984- 1984- 1984- 1984- 1984-2002 2002 2002 2002 2002 2002 2001 2000 1999 1998 1997 NLS q fine scale 0.60 0.59 0.58 0.57 0.56 0.55 0.54 0.53 0.52 0.51 0.50 1984- 1985- 1986- 1987- 1988- 1989- 1984- 1984- 1984- 1984- 1984-2002 2002 2002 2002 2002 2002 2001 2000 1999 1998 1997 Figure C17d. Retrospective CSA estimates of q for Gulf of Maine northern shrimp.
36th SAW Consensus Summary 379
Observed Predicted 2
Autumm Survey Std. Residuals 14 1 12 Autumm Survey Index 1
10 0
8 6 -1 (kg/tow) 4 -1 2
-2 0
68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 00 02 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 Survey Year Survey Year Observed Predicted 2
50 1 Maine Survey Index (kg/tow)
Maine Survey Std Residual 40 1 30 0 20 -1 10 -1 0 -2 1965 1970 1975 1980 1985 1990 1995 2000 2005 19 68 19 70 19 72 19 74 19 76 19 78 19 80 19 82 19 84 19 86 19 88 19 90 19 92 19 94 19 96 19 98 20 00 20 02 Survey Year SurveyYear Observed Predicted 7 25 5 Shrimp Survey Std. Residual Shrimp Survey Index (kg/tow) 3 20 1
15
-1 10
-3 5 -5
-7 0
ar 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 01 1965 1970 1975 1980 1985 1990 1995 2000 2005 Ye 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 Survey Year Sur ve y Ye ar Figure C18. Summary of results from ASPIC analysis of Gulf of Maine northern shrimp biomass dynamics, with residuals.
380 36th SAW Consensus Summary
1.2 1.0 Fishing Mortality 0.8 0.6 0.4 0.2 0.0 1968 1972 1976 1980 1984 1988 1992 1996 2000 surplus production Collie-Sissenwine analysis 50 Stock Biomass (thousand mt) 45 40 35 30 25 20 15 10 5
0 1968 1972 1976 1980 1984 1988 1992 1996 2000 Fishing Season Figure C19. Estimates of fishing mortality (above) and stock biomass (below) for Gulf of Maine northern shrimp from CSA and surplus production (ASPIC) modeling.
36th SAW Consensus Summary 381
Figure C20a. Biomass dynamics of the Gulf of Maine northern shrimp fishery, based on surplus production (ASPIC) modeling (above) and CSA (below) with possible fishing mortality and biomass reference points.
Based on Surplus Production (ASPIC) 1.2 1.0 Fishing Mortality 0.8 0.6 F=0.46 0.4 0.2 F=0.17 1968 2002 0.0 0 5 10 15 20 25 30 35 40 45 50 55 Biomass (thousands of mt)
Based on Collie-Sissenwine Analysis 1.0 0.8 Fishing Mortality F=0.6 0.6 0.4 F=0.34 0.2 1985 2002 0.0 0 5 10 15 20 25 30 35 40 45 50 55 Biomass (thousands of mt) 382 36th SAW Consensus Summary
Figure C20b. Biomass dynamics of Gulf of Maine northern shrimp from ASPIC modeling.
Pr e d ic t e d T r a je c to r y e q u ilib r iu m 70 60 Biomass (thousand mt) 50 68 40 30 20 02 10 0
0 0 .2 0 .4 0 .6 0 .8 1 1 .2 F i s h i n g M o r t a l it y p r e d ic t e d t r a je c t o r y e q u ilib r iu m 14 12 10 Yield (thousand mt) 8 6
68 4
2 02 0
0 0 .2 0 .4 0 .6 0 .8 1 1 .2 F is h in g M o r t a lit y p r e d ic t e d t r a je c t o r y e q u ilib r iu m 14 12 10 Yield (thousand mt) 8 6
68 4
2 02 0
0 10 20 30 40 50 60 70 S t o c k B io m a s s ( t h o u s a n d m t )
36th SAW Consensus Summary 383
5 100 4 80 Eggs per Recruit (% of max)
Yield per Recruit (g) 3 Yield per Recruit 60 Eggs per Recruit 2 40 Fmax 1 F40% 20 F50% F0.1 F20%
0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Fishing Mortality Figure C21. Yield and egg production per recruit for Gulf of Maine northern shrimp.
384 36th SAW Consensus Summary
1200 Recruitment Index (no. age 1.5 per tow) 01 1000 87 800 92 600 90 93 96 400 99 86 03?
94 85 02?
95 88 91 200 00 97 98 89 0
0 2 4 6 8 Spawning Stock Biomass Index (kg/tow)
Figure C22a. Relationship between summer survey indices of Gulf of Maine northern shrimp female biomass the summer before egg hatch to age 1.5 abundance two years later.
Data labels indicate year of egg hatch.
1200 Recruitment Index (no. age 1.5 per tow) 01 1000 87 800 92 600 90 93 400 99 94 96 86 03?
85 91 02? 88 200 95 97 00 89 98 0
0 200 400 600 800 1000 1200 1400 Egg Production Index (thousands)
Figure C22b. Relationship between egg production index for Gulf of Maine northern shrimp the summer before egg hatch to age 1.5 abundance two years later. Data labels indicate year of egg hatch.
36th SAW Consensus Summary 385
Boothbay Harbor Sea Surface Temperature 12 11 Temperature °C 10 9
8 7
6 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 Figure C23. Average annual sea surface temperature in °C at Boothbay Harbor, Maine.
386 36th SAW Consensus Summary
D. ATLANTIC STRIPED BASS The Atlantic Coast striped bass stock is assessed with two separate methods: 1) catch-age based virtual population analysis, and 2) tag release-recovery based survival estimation. Each program is presented in this report as separate segments. The VPA analysis, prepared by the Stock Assessment Subcommittee, is used to evaluate fishing mortality for the mixed coastal stock and provide estimates of abundance and biomass. The tagging analysis, prepared by the Tagging Workgroup, is used to evaluate fishing mortality for specific stocks and averaged results are used to develop a mixed stock mortality estimate. Fishing mortality rates from both programs are compared. A summary of the Chesapeake Bay tag-based direct enumeration study, used to evaluate compliance of the Chesapeake Bay management program with FMP mortality targets, is also presented. The ASMFC Striped Bass stock assessment sub-committee and Technical Committee met in September 2002 to evaluate the status of the striped bass resource.
I. CATCH-AGE BASED VPA ANALYSIS The first analytical assessment using virtual population analysis (VPA) was conducted in 1997 (for years 1982-1996) and reviewed by the 26th Stock Assessment Review Committee at the Northeast Fisheries Science Center. The results of the review were reported in the proceedings of the 26th Northeast Regional Stock Assessment Workshop (26th SAW): SARC Consensus Summary of Assessments (NEFSC Ref. Document 98-03). This report represents the latest in the series of annual assessments with the inclusion of the 2001 catch and survey data.
Commercial Fishery Commercial landings in 2001 totaled 941.7 thousand fish and 6.2 million pounds (2,826 mt)
(Table D1, Table D2). The landings represent a decline of 109.5 thousand fish (10.4%) and of 395.7 thousand pounds (6%) compared to 2000 (Table D8). The Chesapeake Region (Maryland, PRFC, and Virginia) accounts for most of the commercial harvest, 65% by weight and 82% by number (Table D3). Overall, commercial harvest represented 22% by number and 24% by weight of total harvest in 2001, and 29 % of total catch in number (harvest + discard) (Figure D1, Table D2). Commercial harvest was comprised primarily of fish ages 4 to 6 (60% of commercial harvest). Ages 3 through 8 comprised 88.5% of the harvest.
Direct measurements of commercial discards of striped bass were not available. For past assessments that incorporated 1982-97, the estimates were based on the ratio of commercial to recreational released fish tag recovery data, scaled by total recreational discards:
CD = RD*(CT/RT) where:
CD is an estimate of the number of fish discarded by commercial fishery, RD - number of fish discarded by recreational fishery, CT- number of tags returned from discarded fish by commercial fishermen, RT- number of tags returned from discarded fish by recreational fishermen.
36th SAW Consensus Summary 387
Total discards were allocated to gears based on the overall distribution of recovered tags by gear.
Discards by fishing gear were multiplied by gear specific release mortalities and summed to estimate total number of fish killed. The technical committee attempted to improve the estimate of commercial discards for the 1998-2001 period by accounting for spatial distribution of different fishing gear and effort. The ratio of tags recovered in commercial and recreational fisheries and corresponding discards were calculated separately for Chesapeake Bay and the coast. Commercial discards for the Hudson and Delaware Rivers were estimated separately.
Total commercial discards losses for 2001 were estimated as 310,900 fish, representing 7.2% of total removals in number (Figure D1, Table 2, Table 4, Table 9).
Commercial discard proportions at age were obtained using age distributions from fishery dependent and independent surveys done using comparable gear. These proportions at age were applied to discard estimates by gear and expanded estimates summed across all gears. Total commercial discards were dominated by fish of ages 3 to 6.
Recreational Fishery Recreational statistics were collected as part of the MRFSS (Marine Recreational Fishery Statistics Survey) program. Landings (A+B1) in 2001 were 2.0 million fish totaling 19.58 million pounds (8,889 mt) (Table D1, Table D2). The landings represent an increase of 88.3 thousand fish (4.6%) and 2.48 million pounds (14.5%) compared to 2000 (Table D1). The states landing the largest proportion of the recreational landings were New Jersey, Maryland, Virginia, New York, and Massachusetts (Table D6, Figure D2). Overall, recreational landings represented 71% by number and 76% by weight of the reported total landings (Figure D1). Striped bass of age 4 to 8 comprised 75% of landings.
Recreational discards (B2's) declined in 2001 to 13.5 million fish (Table D2) compared to 2000 estimates. Application of an 8% hooking mortality rate resulted in estimated losses of 1.1 million fish (Table D2). The states with the largest proportion of the overall discards were Massachusetts and Maryland (Table D7). Recreational discards represented 25% by number of the total catch (Figure D1, Table D2). Discards of the 1996 year class were greatest among all cohorts both in 2000 and 20001. Total recreational striped bass catch in 2001 was 3.1 million fish. The catch was dominated by ages 4 to 8 (76.5% of total). Total recreational discard and landings losses have been growing steadily between 1982 and 2001, with some intermittent decline in 1998-1999 (Table D10, Figure D3).
Total Catch at Age The above components are totaled by year to produce the overall catch at age matrix for VPA input (Table D11). The total catch of striped bass in 2001 was 4.3 million fish, a decline from 5.04 million fish in 2000. The decline in harvest occurred primarily in ages 2-7 and especially ages 4 and 5 (Figure D4). At the same time there was in increase in the number of harvested fish of age 8 and older with the exception of age 10.
388 36th SAW Consensus Summary
Indices of Abundance Fishery Independent Indices The Maryland gillnet survey of spawning biomass has generally declined since 1993, although there was a strong peak in 1996. The 2002 value was very similar to 2001 about one-half the series average (Figure D5). Values for age-2 were dropped as tuning indices due to frequency of zero catches over time. The New York ocean haul seine index increased considerably for 1996-1998, while the 2001 value decreased from 2000 and was near the 1999 value (Figure D6). The NEFSC spring inshore survey was incorporated as an age-aggregated index in the 1999 assessment, and was used in the 2000 and current assessment as age-specific indices. The aggregated index increased during the early to mid-1990s before declining in 1998 and 1999.
The 2002 value increased to one of the highest in the series (Figure D7). The Rappahannock River, Virginia pound net CPUE was included for the first time in 2001, in an attempt to provide more information on the overall spawning stock. This survey, begun in 1991, showed high abundance in 1999 and 2000, while the 2001 value was just below average (Figure D8). Three age-aggregated trawl indices from Connecticut, New Jersey and Delaware were added in the 2000 VPA (Figure D9). All surveys showed a decline from 1999 to 2001 to near or below average although Connecticut and New Jersey indices increased in 2002.
Juvenile indices from the Chesapeake Bay (Maryland and Virginia) show another very strong recruitment in 2001 (Figure D10). Previous strong cohorts in 1993 and 1996 have been clearly detectable in coast-wide landings during recent years. The juvenile index for the Hudson River was very high in 2001, while the Delaware index was below average (Figure D11). The NY and NJ young-of-year surveys showed overall increasing trends since 1991.
The Maryland age-1 index was slightly above average in 2001, and reflected only a slight upward trend over the last few years (Figure D12). The Long Island age 1 index in 2001 was the highest for the time series (Figure D12).
Fishery Dependent Indices The Massachusetts commercial catch per trip reached the highest level in 2001 (Figure D13).
The Connecticut volunteer angler catch per trip was well above average in 2000 and reached the highest level in 2001 (Figure D14). The index for age 1 (lagged ahead as age 2) was not included in the VPA analysis.
The Hudson River shad fishery by-catch of spawning striped bass (age 8+) was reconfigured by the NYDEC for use as an age-aggregate index in the VPA. This survey increased steadily through 1996, then dropped to the average for 1997-1998. The survey index was well below average in 2000 and 2001 (Figure D15).
Weight at Age Weight at age information was updated for the period 1997-2001. Mean weights at age for the 2001 striped bass catch were determined from available state data. The available data were from Maine and New Hampshire recreational harvest and discards; Massachusetts recreational and commercial catch; New York recreational catch and commercial landings; New Jersey recreational catch; Delaware commercial catch and Virginia recreational and commercial catch.
Weighted mean weights at age were calculated as the sum of weight at age multiplied by the 36th SAW Consensus Summary 389
catch at age in numbers, divided by the sum of catch in numbers. In the VPA model, the estimated weights at age for 2001 were applied to 1997 to 2000 where weight data were unavailable. Details of developing weights at age for 1982 to 1996 can be found in NEFSC Lab Ref. 98-03. Weight at age for the 1982-2001 period is presented in Table D12.
Virtual Population Analysis Catch at Age A catch at age matrix was developed using standard methods described in the previous assessment documents (Anon 2001). Commercial landings at age were estimated by applying corresponding length frequency distributions and age length keys to the reported number of fish landed by the commercial fishery in each state. Length frequencies of recreational landings were based on a combination of MRFSS length samples and volunteer angler logbooks. State specific age-length keys were applied to length frequencies to estimate number of fish at age landed by recreational fishery. Age composition of the recreational discards was estimated using lengths available from volunteer angler logbooks and American Littoral Society data.
All states agencies used striped bass scales to estimate age. However, the Technical Committee was concerned about a problem ageing striped bass. Several recent studies (Secor et al. 1995, Bobko 2002, King 2002) have indicated that scales may not provide a reliable age estimate for older fish, beginning with ages 10 to 12. In previous assessments of striped bass, fish of age 15 and older were combined into a 15+ group. The committee adopted the 12+ configuration as the preferred option because 1) estimation of fewer ages reduced the uncertainty associated with ageing error in older fish 2) the change resulted in a more stable exploitation pattern and 3) the estimates of fishing mortality were more closely aligned with estimates from tag models which do not rely on age data. The ADAPT program, a part of the NEFSC stock assessment software FACT, was used to analyze striped bass populations.
ADAPT model inputs Fishing mortality estimation for age 11, the oldest true age, was based on ages 5 through 10.
Abundance of age classes 1 through 11 in the terminal year was estimated using a Marquardt algorithm. Fishing mortality on the plus group was set equal to the fishing mortality for the last true age and was estimated using a backward method. Natural mortality was assumed constant and equal to 0.15 year-1. The model was run using the iterative re-weighting option in FACT.
Model fit.
All estimates of abundance at age (N) and catchability coefficients (q) were significant at the 0.05 level (T statistic > 1.96, Table D13 ). CVs of the N and q estimates were relatively low (most in the range of 20-30%), indicating a good fit. Estimate of ages 1and 2 abundance had greater CVs (50 and 38%), which were expected due to generally higher variation of indices of abundances of younger ages. Among the catchability coefficient estimates, poor performers were the following indices: NEFSC trawl survey indices for ages 1 and 2 with CVs of 0.5 and 0.38 respectively and Virginia pound net survey indices for ages 1 and 12+ with CVs of 0.49 and 0.33. High variances for these indices were likely caused by the scarcity of either very young (ages 1 and 2) or old fish (ages 10-12+) in the sampling gear. Mean square residuals were 0.95 prior to re-weighting and 0.008 following iterative re-weighting, indicating a good fit of the 390 36th SAW Consensus Summary
model. The correlation between parameters was small, which indicated parameters independence, a desired property.
Each survey used to tune the VPA contributes to the overall variance in the model, and the amount of the total variance attributable to an index is indicated by its partial variance (PV).
Surveys or particular ages of surveys with high PVs are often deleted from assessment runs because they contribute relatively little additional information, and such an approach has been used in the past to trim down the number of surveys. This assessment was a compilation of several stocks and the relative importance of each components contribution to the total harvest and population abundance was unknown. Iterative re-weighting was used to reduce the influence of surveys with high partial variance while retaining the information of each survey concerning the abundance of particular stock components. Iterative re-weighting resulted in very small changes in estimates of abundance and fishing mortality, indicating that none of the indices had performed very poorly.
Fishing Mortality The 2001 average fishing mortality rate (F) for fully recruited ages, 7 through 10 (plus group age minus two), equaled 0.29 and was below current target (0.31) and overfishing values (0.38)
(Table D14, Figure D16). Average fishing mortality for ages 4 through 10, which has been reported as average F in previous assessments, was 0.23 (Table D14, Figure D16). Fishing mortality on ages 3-8, which are generally targeted in producer areas, was 0.19. An F weighted by N was calculated for comparison to tagging results since the tag releases and recaptures also weighted by abundance as part of the experimental design. The VPA F weighted by N for ages 5-10 (age 5 to compare with tagged fish > 28") was 0.21.
A bootstrap procedure was used to estimate variation in fully-recruited fishing mortality (ages 7-10). Results of 500 bootstrap iterations show Fs ranging from 0.21 to 0.36 with an 80%
probability that F was between 0.26 and 0.32 in 2001 (Figure D22).
The VPA indicates that fishing mortality has been steadily increasing since 1989 (Table D14).
The modification of the VPA model to limit the ages to 12 plus changed the estimate of F in the early years of the time series. New estimate in 1982 for fully recruited F was 0.54 (Figure D15) with maximum Fs at age of 0.78.
Partial Recruitment Full recruitment estimated as the back-calculated partial recruitment was at age 7 in 2001, up from age 6 in 2000. Prior to 2000, age at full F varied between ages 7 and 10 (Table D16).
Changes in regulations in 2000 and 2001 to shift exploitation patterns may account for the changes from the 1990s.
Population Abundance Population abundance (stock size as of January 1, 2002) was at the highest level in time series (Table D17, Figure D19) and was estimated at 59.6 million fish. Bootstrap estimates of population abundance are shown in Figure D23. VPA results suggested that the increase was due to very strong 2000 and 2001 year classes. Recruitment of age 1 fish in 2002 (2001 cohort) was estimated as 17.9 million fish, which makes it the biggest cohort ever, exceeding both 1993 and 1996 year classes (Figure D20). This follows the 2000 cohort estimated as 15.5 million fish 36th SAW Consensus Summary 391
which also exceeded 1993 and 1996. Abundance estimates for striped bass age 3 and older have declined slightly since 1999 as the previously strong cohorts move through the fishery.
However, both the 1993 and 1996 year classes remain the most abundant at age in the time series.
Spawning Stock Biomass All VPA runs indicated that spawning stock biomass (SSB) has been growing steadily since 1982 and reached the highest level in 2001 (Figure D21). However, SSB growth was slowed after 1998. Female SSB estimates are of 25.8 mt in 2001.
Retrospective Patterns A retrospective analysis was conducted on the VPA results with successive terminal years extending back to 1995, in order to determine trends in estimation of F or total abundance in the terminal year. The analysis revealed that there was little evidence of retrospective bias in the assessment. However, there was a tendency of overestimation of age 1 abundance by the model.
Sensitivity Analysis Due to the uncertainty in age determination, sensitivity runs were made for the VPA using a 13+
group. Changing the plus group ages had a significant change in the estimates. The average F for ages 4 to 11 was 0.32, ages 8 to 10 equaled 0.4 and average F for ages 3 to 8 was 0.22.
Stock size estimates were also influenced, as 1+ abundance with 13+ decreased to 52.6 million fish compared to 59.6 million with 12+. Recruitment estimates at age 1 also declined by 1.8 million fish to 16.1 million.
The overall trend appears to be a decrease in fishing mortality and increase in stock size estimates as the plus group is reduced in age.
II. TAGGING PROGRAM ANALYSIS Introduction This report summarizes results from analyses of tagging data from the U.S.F.W.S. Cooperative Striped Bass Tagging Program. The results include estimates of instantaneous fishing mortality (F) and survival (S) rates. Estimates of F and S are provided with and without correction for live release bias. Also, included are QAICc estimates and weights used for model selection and model averaging, length frequency of tag releases, age frequency of recaptures, geographic distributions of recaptures by month, and estimates of catch and exploitation rates by program.
Description of Tagging Programs:
Eight tagging programs provided information for this report, and have been in progress for at least nine years. Producer area tagging programs operate mainly during spring spawning, and use many capture gears, such as pound nets, gill nets, seines and electroshocking. Coastal programs tag striped bass from mixed stocks during fall and use several gears including hook &
line, seine, gill net, and otter trawl. Most producer area and coastal programs tag striped bass during routine state monitoring programs. The Western Long Island Survey seines striped bass 392 36th SAW Consensus Summary
from May through October in bays along the western end of Long Island, New York; data from May through August are most consistent and were used for tag analysis.
Tag release and recapture data are exchanged between the U.S. Fish and Wildlife Service (USFWS) office in Annapolis, MD, and the cooperating tagging agencies. The USFWS maintains the tag release/recovery database and provides rewards to fishermen who report the recapture of tagged fish. Through July of 2002, a total of 385,891 striped bass have been tagged and released, with 70,118 recaptures reported and recorded in the USFWS database (Tina McCrobie, personal comm.).
Analysis Methods:
The Striped Bass Tagging Committee analysis protocol is based on assumptions described in Brownie et. al. (1985). The tag recovery data is analyzed in program MARK (White, 1999).
Important assumptions of the tagging programs (as reported in Brownie 1985) are as follows:
- 1. The sample is representative of the target population.
- 2. There is no tag loss.
- 3. Survival rates are not affected by the tagging itself.
- 4. The year of tag recoveries is correctly tabulated.
Other assumptions related to the modeling component of the analyses include:
- 5. The fate of each tagged fish is independent of the fate of other tagged fish.
- 6. The fate of a given tagged fish is a multinomial random variable.
- 7. All tagged individuals of an identifiable class (age, sex) in the sample have the same annual survival and recovery rates.
The tagging committee calculates maximum likelihood estimates of the multinomial parameters of survival and recovery based on an observed matrix of recaptures (using Program MARK).
The analysis protocol follows an information-theoretic approach based on Kullback-Leibler information theory and Akaikes information criterion (Burnham and Anderson 1988), and involves the following steps. First, a full set of biologically-reasonable candidate models are identified prior to analysis. Various patterns of survival and recovery are used to parameterize the candidate models. These include models, which allow parameters to be constant, time specific, or allow time to be modeled as a continuous variable. Other models allow time periods to coincide with changes in regulatory regimes established coastwide. Candidate models used in the analyses of striped bass tag recoveries are listed and described below.
S(.) r(.) Constant survival and reporting S(t) r(t) Time specific survival and reporting S(.) r(t) Constant survival and time specific reporting S(p) r(t) *Regulatory period based survival and time specific reporting S(p) r(p) *Regulatory period based survival and reporting 36th SAW Consensus Summary 393
S(.) r(p) *Constant survival and regulatory period based reporting S(t) r(p) *Time specific survival and regulatory period reporting S(d) r(p) *Regulatory period based survival with unique terminal year and regulatory period based reporting S(v) r(p) *Regulatory period based survival with 2 terminal years unique and regulatory period based reporting S(Tp) r(Tp) *Linear trend within regulatory period for both survival and reporting S(Tp) r(p) *Linear trend within regulatory period survival and regulatory period based reporting (no trend)
S(Tp) r(t) *Linear trend within regulatory period survival and time specific reporting (no trend)
- Periods 1 = { 87- 89}, 2 = { 90- 94}, 3 = { 95- 2001}
Candidate models are fit to the tag recovery data and arranged in order of fit by the second order adjustment to Akaike's information criterion (AICc) (Akaike, 1973; Burnham and Anderson, 1992). If overdispersion is detected, then an estimate of the variance inflation factor (i.e., c-hat) is used to adjust AICc (after adjustment, AICc is called QAICc; Anderson et al 1994). Annual survival is calculated as a weighted average across all models, where weight is a function of model fit (Burnham and Anderson 1998; Smith et al. 2001). Model averaging eliminates the need to select the single best model, allowing the uncertainty of model selection to be incorporated into the variance of parameter estimates (Burnham and Anderson 1998; Smith et al.
2001). Also, the committee uses a goodness-of-fit bootstrap procedure (included in program MARK) to estimate the probability that the fully time saturated model fits the data. At the Striped Bass Technical/Stock Assessment meeting (10-12 September 2002), it was suggested that a probability under 0.2 represents lack of fit; this is an arbitrary cutoff point but we use it herein to indicate model fit.
Since survival cannot be uniquely estimated for the terminal year in the fully time saturated
{S(t)r(t)} model, the time saturated model is excluded from the model averaged survival estimate for the terminal year only. The final steps involve adjusting the estimates of survival for reporting rate (Kahn, 2001) and bias due to live release (Smith et al. 2001). Instantaneous fishing mortality (F), not directly estimated by these analysis procedures, is determined by converting survival (S) to total mortality (Z) and subtracting a constant value for natural mortality (M) of 0.15. Using this technique, natural mortality is held fixed, and any change in total mortality (Z) results in an equal change in fishing mortality (F).
Results The 2001 weighted-mean instantaneous fishing mortality (F) was 0.53 for >= 18 inch fish from producer area (Delaware and Maryland) tagging programs (Table D20). This weighted mean excluded Hudson River (data were unavailable for 2001) and Virginia (because of lack of fit for the full parameterized model). For the subset of >= 28 inch striped bass, the weighted mean 394 36th SAW Consensus Summary
fishing mortality (F) in 2001 was 0.16 (Table D21). The weights used in the calculations were as follows: Delaware (0.10) and Maryland (0.90). These were modified from the previous weight scheme [Hudson (0.13); Delaware (0.09); and Chesapeake Bay (0.78), with MD (0.67) and VA (0.33)] as provided from G. Shepherd (pers. comm.). The weight scheme was modified because of the lack of Hudson River data and the lack of fit of the full parameterized model with Virginia data.
A 2001 unweighted-mean instantaneous fishing mortality (F) was not calculated for >= 18 inch fish from the coastal mixed stock tagging programs (Table D20). Survival estimates from three of the four coastal tagging programs were not representative; MADFW primarily tags fish larger than 28 inches, and GOF bootstrap analyses indicated a lack of model fit of data from NYOHS and NCCOOP. For striped bass tagged at twenty-eight inches and greater in total length (believed to represent those fish fully recruited to the coastal fisheries) the 2001 unweighted-mean fishing mortality was 0.09 (Table D21). This unweighted mean was calculated with data from MADFW, NYOHS, and NJDEL, but excluded NCCOOP because of lack of model fit.
In general, fishing mortality estimated by tag-based survival analyses has increased in recent years for the >= 18 inch group, and decreased for the >= 28 inch group. This relationship is consistent with recent changes to regulations that have shifted harvest to smaller fish.
Tables D22 and D23 provide the raw estimates of survival from MARK, and components of the live release bias adjustment. For most tagging programs, the proportion of >= 28 inch fish released alive was lowest within the years of 1996 to 1999; these estimates in recent years have increased slightly (Table D23). If the entire time series is considered, then live release bias has decreased since the late 1980's and early 1990's and may result from lowered size limits. The overall decreasing trend in the number of fish released alive (based on tag data) differs from recent MRFSS reports.
For bias adjustment calculations, the committee applies an 8% mortality to live releases, because most live releases are captured with hook and line. Also, a reporting rate of 0.433 is used to adjust survival and fishing mortality rates (based on a high reward tag study of striped bass released in Delaware; D.Kahn, pers. comm.).
A GOF bootstrap test indicated that most time saturated models fit the data (exceptions included the >= 18 inch group of NYOHS, and both size groups of VARAP and NCCOOP; Tables D22 and D23).
Tables D24 and D25 provide the Akaike weights used to calculate the model averaged survival estimates for each program. Those highlighted were the highest weighted models for that program. These are provided so that the reader may evaluate the model (or models) that influence the overall results. In nearly each case, the best fitting models inferred time or regulatory period specific survival or reporting. For several programs, a model of trend within regulatory period received highest weight. The only case where a model of constant survival and reporting received highest weight was for fish greater than twenty-eight inches total length in the Virginia/Rappahannock producer area program.
36th SAW Consensus Summary 395
Tables D26 and D27 provide the total length frequencies of fish tagged and released by program for 2001 and the age frequencies of 2001 (year) recaptures. The length frequency data show the relative differences within and between fish tagged on the coast and in producer area programs.
The bimodal length frequencies of producer area programs are probably related to differences between sexes. The coast programs exhibit single modes, likely related to differences in program design and gear type. In general, the Massachusetts program (which captures fish with hook and line) releases proportionally more large fish than other coastal programs, whereas the North Carolina trawl survey releases proportionally more small fish than other tag programs.
Age distributions of 2001 recaptures are problematic since few programs assign ages to all tagged fish. Hence, fish not aged at release cannot be assigned an age at recapture. The greatest proportions of recaptures were among ages four through eight, which included 13.3, 25.4, 16.5, 12.4, and 10.1% of the total. In general, these cohorts accounted for 84% of recaptures from fish tagged on the coast, and 64% of those from producer areas.
Table D28 provides geographic distributions of recaptures by state and month during 2001.
Northward spring movements followed by southward returns during fall are consistent across programs and reflect migration patterns and fishing effort.
Tables D29 through 12 provide results from the Western Long Island Survey of juvenile striped bass (ages 1, 2, and 3+). These results indicate a decrease in total mortality as age increases from 1 to 3+.
Trends in encounter and exploitation rates:
Annual catch rates and annual exploitation rates were estimated with tag recoveries of striped bass released by seven agencies (1987 - 2001) of the Cooperative Striped Bass Tagging Program (Tables D32 to D35). Previous estimates of VA-York (1991 - 1999) and NYHUD (1988 - 2000) are included for comparison. Each time series of annual catch rates and annual exploitation rates reflects trends in fishing effort and exploitation, respectively.
Catch and exploitation rates are estimated from recaptures of two size groups (>= 18 inch and >=
28 inch) during the first year after release. Adjusted R/M ratios were used as described below (Reporting rate = 0.43, hooking mortality rate = 0.08, Rk = killed recaptures, RL = recaptures released alive):
(1) Annual catch rate = (R / 0.43) / M (2) Annual exploitation rate = ((Rk + RL
- 0.08) / 0.43) / M Herein, we report trends across the entire time series by program. Overall increases in annual catch rates and annual exploitation rates from 1987 - 1997 or 1987 - 1998 suggest an increase in fishing pressure over that part of the time series, but recent estimates (i.e., the previous two years) of annual catch rates and annual exploitation rates have decreased for most tagging programs.
In general, estimates of exploitation rates are consistent with estimates of F (from survival analyses) as reported above for >= 28 inch fish, but not with those reported for >= 18 inch fish.
396 36th SAW Consensus Summary
III. STATUS OF INDIVIDUAL STOCKS A coast-wide stock of striped bass is comprised of several populations, primarily Hudson River, Delaware Bay and Chesapeake Bay. It is equally important to maintain individual stock at healthy level so that over-fishing does not occur at the local level. For that purpose we report estimates of fishing mortality and population characteristics for each individual stock.
Chesapeake Bay Fishing mortality Tag-based estimates of fishing mortality in 2001 for the Chesapeake Bay stock were available only from the Maryland spring tagging program and the direct enumeration study conducted through the calendar year of June 2001-June 2002. For fish >28 inches, the spring estimate of F
= 0.13 was lower than the N-weighted VPA F estimates of 0.27 and 0.37 on ages 8-10 (12+) and 8-11 (13+), respectively. It should be noted that the tag-based F and N-weighted VPA F are not directly comparable to the reference point because of the methods used to calculate that measure.
A direct enumeration study to estimate the bay-wide fishing mortality based on the tag release and recovery data is conducted by Maryland and Virginia since 1993. The multiple release design and analysis used in this study was reported in Hebert et. al. 1997; Goshorn et al. 1998; Goshorn et al. 1999; Goshorn et al. 2000; Hornick et al. 2000; Hornick et al. 2001. Striped bass were tagged and released throughout the Chesapeake Bay prior to and during the recreational fishing seasons for each respective jurisdiction during four release rounds in Maryland, and three in Virginia. Jurisdictional regions within the Chesapeake Bay were open for recreational striped bass fisheries for a combined total of approximately 31 weeks (6/1/01 -
12/31/01) during the 2001 fall season. All tagging was done cooperatively with commercial watermen. Tag recoveries were handled and recorded by each management jurisdiction and by the U. S. Fish and Wildlife Service (USFWS). USFWS internal anchor tags were applied to 6,663 striped bass. A logistic model was applied to tag recovery and release data. The proportion of the number of recovered tags to the number of tags released was the response variable and the explanatory variables consisted of one categorical variable (interval number, which accounted for unequal interval lengths) and two binary variables, disposition and angler type Estimates of exploitation for the recreational/charter season were converted to instantaneous rates for each round and summed across intervals to determine F for the recreational/charter fishery (FR). This estimate was then adjusted to include the Chesapeake Bay resident portion of the commercial and recreational fisheries that occurred during summer 2001, winter 2001-2002 and during spring of 2002, respectively. The expanded estimates of total F were calculated based on weighting of recreational/charter estimates of FR by proportional additions of spring recreational or commercial harvest in numbers. The estimate of the Chesapeake Bay-wide F (FBay) for 2001 is FBay= 0.23. Non-harvest mortality (0.10) was added to the point estimate of F = 0.13 to obtain the final estimate of bay-wide fishing mortality of FBay
= 0.23 for 2001. The final estimate of bay-wide F (FBay = 0.23) is below the Atlantic States Marine Fisheries Commissions (ASMFC) determined 2001 target fishing rate of F = 0.28 for the Chesapeake Bay. A time series of fishing mortality estimates derived by this method is presented in Table D38.
36th SAW Consensus Summary 397
Spawning stock Spawning stock relative abundance (ages 8+) has been increasing since 1999. The index increased to 79.81 in 2001, but dropped slightly in 2002 to 72.7. Although the spawning stock index dropped in 2002, this value is well above the 1985-2001 average of 46.6 and is equivalent to the 1993-1998 levels.
Recruitment Both Maryland and Virginia index of YOY striped bass abundance (geometric mean) in 2001 was well above the 1957-2000 average. These observations indicated that 2001 was an excellent recruitment year. At the same time the 2002 index was well below the 1957-2001 average.
Hudson River Fishing mortality Data from 2001 have not been processed due to lack of staff at NYDEC; therefore; no tag-based estimates were available for the Hudson River.
Spawning stock Spawning stock relative abundance (gillnet CPUE; ages 8+) increased slightly in 2001 to 633.2; however, the index is still below the 1985-2000 average of 746.9.
Recruitment The Hudson River index of YOY striped bass abundance (geometric mean) increased to 22.98 in 2001. The 2001 value is well above the 1979-2000 average of 13.32, indicating that 2001 was a relatively good year of recruitment for striped bass.
Delaware Bay Fishing mortality Tag-recapture data is employed in two analyses, a Petersen exploitation estimate and an estimate of F based on survival modeling with MARK program software. The two sets of estimates have been the highest on the coast for the last several years. Both estimates, when translated into F, are F weighted by N. The exploitation estimate for 2001 was 28%, which translates into F2001 =
0.36. The 2001 F estimate from the MARK program with trend models included was F2001 =
0.42. If trend models are eliminated, the MARK estimate was F2001 = 0.35. The Delaware River stock suffers high levels of entrainment mortality from the Salem Nuclear Generating Station.
This mortality on YOY larvae and juveniles has been estimated as averaging 32% per year, in the worst case of no compensatory increase in survival of those YOY fish escaping entrainment and impingement.
Spawning stock The spawning stock survey occurs in April and May on the spawning grounds in the tidal freshwater Delaware River from Wilmington through Philadelphia. Two agencies co-operate in this survey, which tags fish and develops Catch Per Unit Effort estimates of abundance in standardized surveys. The Delaware Division of Fish and Wildlife (DDFW) employs electrofishing gear in a formal systematic sampling design (this type of design is randomized),
while the Pennsylvania Fish and Boat Commission (PFBC) also employs electrofishing gear, but in a fixed design. Trends in overall abundance are flat from 1995-2001 for the PFBC and 398 36th SAW Consensus Summary
indicate a slow decline in the DDFW estimates for the period 1996-2001. Further analysis will be conducted. The more extensive DDFW data shows an increase in larger, older fish in recent years, but a decline in recruitment of younger age groups into the spawning stock.
Recruitment A YOY survey is conducted annually by the New Jersey Division of Fish, Game and Wildlife employing a beach seine. The index was extremely low at the beginning of the time series in 1980, then gradually climbed to a value of 1.03 in 1989. Since then, it has fluctuated without trend between about 1.00 and 2.00. The 2001 index was 1.07.
IV. DISCUSSION VPA Analysis The results of the VPA analysis indicate that the coastal stocks of striped bass remain at or below the target F and are not in an overfished condition. Recruitment continues to increase to record levels while spawning stock biomass estimates are at the highest level in the time series. Catches in the recreational fishery also continue to increase.
The sensitivity of the VPA model to changes in the plus grouping was of concern to the Technical Committee. The primary purpose of reducing the plus group was to reduce problems associated with age error. This change also illustrated the problems associated with defining plus groups and oldest age F estimates in an age-structured model. A change in the plus group influenced the calculated exploitation pattern and consequently the average F at fully recruited ages. With more ages in the model, the average F tended to be higher. However, due to the direction of the potential age bias in the inputs, it is expected that the model would be over-estimating F by incorporating older and possibly incorrect ages. Consequently there is more uncertainty in the VPA estimates than are indicated by the bootstrap results.
Tag Analysis There are several sources of uncertainty associated with the estimation of survival and recovery parameters in the tagging analysis for striped bass. The primary source involves the violation of assumptions basic to all tag recovery modeling, as mentioned earlier in this text. Others involve ad-hoc methods employed to correct for live release bias, as well as the use of a contemporary reporting rate to adjust retrospective recaptures. In addition, the best fitting model for several programs in the >= 18 inch total length group was the time saturated model, which is omitted from the suite of models during model averaging due to constraints on the terminal year survival estimate. The application of a constant value for natural mortality across all groups and time does not allow for potential changes in natural mortality, and dictates that changes in survival result only in changes in fishing mortality.
Also, GOF bootstrap analyses indicated a lack of fit for time saturated models from some tagging programs. The c-hat adjustment corrects for lack of fit associated with overdispersion, but will not correct lack of fit when data do not support the full parameterized model. In the latter case, additional thought toward selection of candidate models may be necessary. In general, lack of fit occurred in program results with highest weight on the full parameterized (time saturated) model 36th SAW Consensus Summary 399
and large year to year variation in survival estimates. The tagging committee plans to examine the use of covariate models in future analyses; preliminary covariate analyses with the NCCOOP data reduced problems with the full parameterized model and extreme year to year variation in survival estimates.
Additionally, the tagging committee will examine the use of trend models, which have been used to fit increasing or decreasing trends in survival estimates. In all cases for the 2001 analysis, when trend models were given highest weight (such as DE and MD for the >= 18 inch group, and DE and NJ for the >= 28 inch group), F estimates of the terminal year were high. This effect also occurred for the terminal year estimates of NYOHS, NJ, and VA for the >= 18 inch group, because the trend models received highest weight after omission of the time saturated model.
Resolution of many of these issues will take time, and may require a change in the analysis protocol adopted by the tagging committee. It is likely that additional research is required to investigate the differences in release mortality associated with different capture gears, or that the committee may need to investigate other methods to directly determine instantaneous fishing mortality (F). Some solutions may take longer, as the state of the theoretical science is generally in advance of any practical application. Perhaps, as in the model averaging approach, we should not focus on individual tagging program results, but instead consider the aggregate, and examine trends applicable to the whole stock over time.
TAG-VPA F Comparison Results from the VPA average F and the tagging estimates of F are not directly comparable.
Since the tag releases are made proportional to abundance, the appropriate comparison between tag and VPA Fs are the tag F with the VPA F weighted by N. Tag results are for striped bass 28 inches and greater. Therefore, comparison was between VPA Fs weighted by N for ages 5 to 10 and average tag Fs from coastal programs (only positive F values were included in the average).
The results from the two independent estimates of fishing mortality show the same increasing trend over time. The VPA Fs tend to be slightly higher than the average coastal tag Fs (Figure D24, D26), although the VPA estimate is not statistically different based on 95% confidence intervals. The NC offshore winter tag program provided the closest comparison with the VPA results as shown in Figure D25. Part of the variation between the two is the result of the different models used for the estimation.
V. CONCERNS The uncertainty associated with ageing striped bass with scales remains a problem. A thorough analysis of the scale and otolith database is required to develop a reliable procedure for correction of ages estimated with scales. In response to this problem, the ASMFC will convene an ageing workshop during the winter of 2003 to evaluate the problem and develop some possible solutions.
The Technical Committee remained concerned about the high levels of fishing mortality on the Delaware River stock as determined by tagging estimates of survival.
400 36th SAW Consensus Summary
Some members of the Technical Committee were concerned that the distribution of larger striped bass has shifted to offshore waters as the population has increased in abundance. Since the EEZ is closed to harvest and there is limited fishery independent survey data for older striped bass beyond state waters, these fish may not be represented in the assessment. Low tag recovery of fish tagged in MA may be an indication of shifting distribution.
Some members of the Technical Committee were concerned that the VPA is not adequately robust when dealing with a mixed stock such as coastal striped bass. Other methods that are capable of directly accounting for mixed stock management units should be explored in the future. Some members were also concerned that the tag based estimates of survival among coastal programs were so variable. It is possible that the assumption of mixing and dispersal is not being adequately met to provide a comprehensive estimate of mortality.
Developing consensus management recommendations remains difficult when faced with two separate assessment techniques. Methods that combine catch, survey, and tag data into a single analytical framework should be explored.
VI. SARC COMMENTS VPA Analysis Selection of ages 5-10 to estimate the F on age 11 will produce strong dome shaped PR. A flat top PR is not appropriate. When fishing offshore is prohibited, it provides a refuge for large fish and may result in a dome shape PR. Availability may be declining not because of the decline of fish numbers but because they are moving out of the area. Partial recruitment calculation is shifting around with age class dominance.
Including ages 5 and 6 may be helpful early on in the time series when there were not many age 7 and older fish, but that is not helpful now. Need to be careful how you calculate the F on the oldest true age. Use the previous age to estimate the F on the first age in the plus group (ie use age 10 to estimate the F on age 11). That allows for a greater potential for allowing a dome to occur. There would be an even stronger dome if the age range were 4-10 rather than 5-10. Catch on age 4, 5 and 6, tagging information, fish moviement into an area where fishing is not occurring- all of these are evidence for a domed shaped curve.
Plots of residual time series are needed to judge the quality of fit.
Estimates of F are sensitive to the plus group. For example, in the 13+ run, the F in 2001 is 0.4 (Table D14 ).
There are 4 years were the plus group is greater than the sum of the previous plus group.age 11.
There is no description in the document that describes how the target and threshold Fs were derived in Amendment 5. Need some background on the derivation of the target and threshold Fs.
The document should include table of F by age and year in addition to average Fs.
36th SAW Consensus Summary 401
It appears that there is a problem with age precision beyond age 8 in MA scale reading study.
The mean weight at age in some cohorts is going down. This is because of the bias and imprecision in ageing.
The SARC recommends developing a calibration matrix that creates conversion between scales and otoliths. This is a very important outcome from the intended ageing workshop.
The issue of an appropriate VPA configuration should also address allowing for a dome shaped selectivity pattern and an objective discrimination of which tuning indices were included or withheld from the model.
Indices should be tested through the randomization tests, PCA.
Range of the stock distribution by season and fraction of the stock that would be present in a certain area should be considered in parallel with the indices selection. All of the indices that are north of the spawning areas may be capturing the stock as a whole and maybe those indices should be provided with greater weight in the VPA.
Error bars should be included around the estimators if it is based on ratios or bootstrap should be done if ratios are not used.
Use the MRFSS estimate for recapture rate (1 in 13 fish is actually retained?) as an independent estimate of recaptures.
Tag Analysis Tagging in Delaware is done in the Delaware River, this may be a reason for the increase in DE estimates.
Assume the tagging reporting is constant because there arent better estimates. Reporting rates may vary.
Including the constant survival models is inappropriate if one wants to be able to compare the tagging estimates and the VPA results.
28 or greater (at tag and release) are assumed to be about age 7. Have not run age based models.
Analysis uses 28 or greater as a group and that is compared to the 5-10 ages. Probably should be examined a bit further.
Diminishing the quality of the parameter estimates when including models that are not given much weight, although it may not significantly influence the output, it is going to influence the uncertainty. This may be a reason to throw out these models.
Tag analysis implies a very high dome because the F is greater on the 18 and greater (tag analysis) compared to the F estimate from the tag analysis for 28 or greater.
Fish captured more than once are only included the first time around in the analysis.
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Research recommendations.
Conduct a workshop to evaluate an appropriateness of scales in ageing old fish.
Explore applicability of Bayesian framework to striped bass assessment.
Develop the model that will combine VPA and tagging data.
V. References Anonymous 2001. 2001 Stock Assessment Report for Atlantic Striped Bass. Atlantic States Marine Fisheries Commission. Striped Bass Technical Committee.
Akaike, H. 1973. Information theory as an extension of the maximum likelihood principle. In Second International Symposium on Information Theory. Edited by B.N. Petrov and F.
Csaki. Budapest: Akademiai Kiado.
Anderson, D.R., K.P. Burnham, and G.C. White. 1994. AIC model selection in overdispersed capture-recapture data. Ecology 75:1780-1793.
Bobko S. 2002. A Comparison of Otolith and Scale Age Determination for Striped Bass harvested in Virginia. VMRC/ODU Age and Growth Laboratory Center for Quantitative Fisheries Ecology Old Dominion University. Draft Manuscript.
Brownie, C., D.R. Anderson, K.P. Burnham, and D.R. Robson. 1985. Statistical Inference from Band Recovery - a handbook. 2nd ed. U.S. Fish and Wildlife Service Resource.
Publication. No 156.
Burnham, K.P., and D.R. Anderson. 1992. Data-based selection of an appropriate biological model: The key to modern data analysis. In. Wildlife 2001: Populations. Edited by D.R.
McCullogh and R.H. Barrett. London:Elsevier Science Publications.
Burnham, K.P., and D.R. Anderson. 1998. Model selection and inference: a practical information theoretical approach. Springer-Verlag, New York.
Goshorn, C.J., B.A. Rodgers, and R.E. Harris. 2000. Revised estimate of the 1998 striped bass rate of fishing mortality in Chesapeake Bay. Maryland Department of Natural Resources.
Annapolis, Maryland, and the Virginia Institute of Marine Science, Gloucester Point, Virginia. 29 pp.
Goshorn , C.J., D.R. Smith, B.A. Rodgers, L.D. Warner and H.T. Hornick. 1999. Revised estimate of the 1997 striped bass rate of fishing mortality in Chesapeake Bay. Maryland Department of Natural Resources. Annapolis, Maryland, and the U.S. Geological Survey, Leetown Science Center, Kearneysville, West Virginia. 29 pp.
Goshorn , C.J., D.R. Smith, B.A. Rodgers and L.D. Warner and H.T. Hornick. 1998. Estimates of the 1996 striped bass rate of fishing mortality in Chesapeake Bay. Maryland Department of Natural Resources. Annapolis, Maryland, and the U.S. Geological Survey, Leetown Science Center, Kearneysville, West Virginia. 31 pp.
36th SAW Consensus Summary 403
Hebert, K.P, D.R. Smith, P.W. Jones. 1997. Estimates of the 1995 Striped Bass Rate of Fishing Mortality in Chesapeake Bay. Maryland Department of Natural Resources, Annapolis, Maryland, and the U.S. Geological Survey, Leetown Science Center, Kearneysville, West Virginia. 33 pp.
Hornick, H.T., B.A. Rodgers, R.E. Harris and J. Zhou. 2000. Estimate of the 1999 striped bass rate of fishing mortality in Chesapeake Bay. Maryland Department of Natural Resources.
Annapolis, Maryland, and the Virginia Institute of Marine Science, Gloucester Point, Virginia. 10 pp.
Hornick, H.T., B.A. Rodgers, and R.E. Harris. 2000. Estimate of the 2000 striped bass rate of fishing mortality in Chesapeake Bay. Maryland Department of Natural Resources.
Annapolis, Maryland, and the Virginia Institute of Marine Science, Gloucester Point, Virginia. 11 pp.
Kahn, D.M., and C.A. Shirey. 2000. Estimation of Reporting Rate for the U.S.F.W.S.
Cooperative Striped Bass Tagging Program for 1999. Report to the ASMFC Technical Committee. Mimeo 5 pp.
Northeast Fisheries Science Center. 1998. 26th Northeast Regional Stock Assessment Workshop:
stock assessment review committee (SARC) consensus summary of assessments. NEFSC Reference Document 98-03.
Secor D.H., Trice T.M., Hornick H.T. 1995. Validation of otolith based ageing and a comparison of otolith and scale based ageing in mark recaptured Chesapeake Bay Striped Bass, Morone saxatilis. Fish. Bull 93:186-190.
Smith, D.R., K.P. Burnham, D.M. Kahn, X. He, C.J. Goshorn, K.A. Hattala, and A.W. Kahnle.
2000. Bias in survival estimates from tag recovery models where catch-and-release is common, with an example from Atlantic striped bass (Morone saxatilis). Canadian Journal of Fisheries and Aquatic Science 57:886-897.
White, G.C., and K.P. Burnham. 1999. Program MARK - survival estimation from populations of marked animals. Bird Study 46: 120-138 404 36th SAW Consensus Summary
VI. Tables and Figures VPA Tables and Figures Table D1. Total Atlantic Coast harvest of striped bass in metric tons and numbers from 1982 to 2001.
Year Commercial Recreational Total MT N MT N MT N 1982 992 428,630 1,144 217,256 2,136 645,886 1983 639 357,541 1,217 299,444 1,856 656,985 1984 1,104 870,871 579 114,463 1,683 985,334 1985 4,312 174,621 372 133,522 4,684 308,143 1986 68 17,681 501 114,623 569 132,304 1987 63 13,552 388 43,755 451 57,307 1988 117 33,310 570 86,725 687 120,035 1989 91 7,402 332 37,562 423 44,964 1990 313 115,636 1,010 163,242 1,323 278,878 1991 460 153,798 1,653 262,469 2,113 416,267 1992 638 230,714 1,830 300,180 2,468 530,894 1993 777 312,860 2,564 428,719 3,341 741,579 1994 805 307,443 3,084 565,167 3,889 872,610 1995 1,555 534,914 5,675 1,089,183 7,230 1,624,097 1996 2,178 766,518 6,003 1,175,112 8,181 1,941,630 1997 2,679 1,058,181 7,267 1,515,296 9,946 2,573,477 1998 2,936 1,223,828 5,771 1,366,353 8,707 2,590,181 1999 2,941 1,103,812 6,245 1,319,794 9,186 2,423,606 2000 3,003 1,051,275 7,756 1,924,001 10,759 2,975,276 2001 2,826 941,733 8,889 2,012,314 11,715 2,954,047 Table D2. Total 2001 striped bass discard and harvest in numbers and % of total by fishery component.
Fishery Component Discard Discard Harvest Total Losses Catch Recreational 13,456,350 1,076,508 2,012,314 3,088,822 Commercial 2,023,439 310,900 941,733 1,252,633 Sampling 2,343 2,343 Total 15,479,789 1,387,408 2,956,390 4,343,798 Percent of Total Fishery Component Discard Harvest Total Losses Catch Recreational 24.78% 46.33% 71.11%
Commercial 7.16% 21.68% 28.84%
Sampling 0.05% 0.05%
Total 31.94% 68.06% 100.00%
36th SAW Consensus Summary 405
Table D3. Atlantic Coast striped bass commercial harvest in numbers at age by state, 2001.
Age State 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Maine 0 New Hampshire 0 Massachusetts 0 0 0 0 0 0 1,877 7,090 6,673 8,342 9,176 3,962 2,294 626 208 40,248 Rhode Island 0 0 16 122 779 1,543 1,841 1,841 744 934 1,139 589 614 458 297 10,917 Connecticut 0 New York 0 0 0 209 6,842 10,682 10,263 23,668 3,700 1,745 768 349 70 58,296 New Jersey 0 Delaware 0 0 34 1,247 10,932 9,448 5,926 5,349 946 89 402 34,373 Maryland 0 0 81,433 141,666 169,554 83,660 32,555 14,582 5,389 4,245 2,749 1,983 795 199 538,808 PRFC 0 0 1,492 40,281 32,396 6,394 3,410 2,558 853 213 0 0 0 213 87,809 Virginal 0 165 3,215 6,077 20,234 26,951 30,885 33,327 9,352 7,183 4,050 4,998 750 1,000 159 148,346 North Carolina 0 0 0 0 0 0 69 3,680 5,710 8,415 3,676 878 439 69 22,936 Total 0 165 86,190 189,602 240,736 138,678 86,825 92,095 33,367 31,165 21,960 12,759 4,962 2,564 665 941,733 Table D4. Estimated Atlantic Coast commercial discard losses at age for 2001.
Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total 2001 1 2,638 58,079 77,958 88,808 29,410 18,877 11,613 9,664 6,371 4,778 1,957 737 10 0 310,900 Table D5. Reported scientific removals at age for 2001.
Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total 2001 0 15 337 956 660 120 63 56 50 51 21 10 3 1 2,343 406 36th SAW Consensus Summary
Table D6. Total Atlantic Coast striped bass recreational landings in numbers at age by state, 2001.
Age State 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Maine 0 0 12,070 19,382 17,763 5,406 1,862 3,206 7 35 115 42 29 27 6 59,947 New Hampshire 0 0 0 397 1,165 2,289 3,124 2,394 1,804 1,192 1,604 895 429 0 0 15,291 Massachusetts 0 0 0 5,058 6,488 38,087 85,493 71,709 41,694 14,091 13,709 6,312 3,948 1,442 0 288,032 Rhode Island 0 0 0 262 12,953 24,631 19,322 14,236 3,082 1,787 1,746 1,112 661 197 138 80,127 Connecticut 0 0 0 1,027 12,187 11,205 7,608 6,632 3,575 167 312 1,001 1,460 2,731 5,507 53,412 New York 0 0 0 4,173 23,885 55,309 48,074 36,796 7,233 5,135 4,351 1,270 2,026 541 917 189,710 New Jersey 0 0 0 18,505 105,286 159,608 116,225 70,521 39,494 21,947 17,285 6,330 2,989 1,495 523 560,208 Delaware 0 0 736 432 2,026 3,481 10,012 13,089 3,312 1,655 2,926 2,548 671 307 0 41,195 Maryland 0 47,386 81,500 87,717 31,086 33,625 21,125 18,583 19,320 14,548 15,510 5,525 4,434 1,241 956 382,557 Virgina 0 559 17,487 31,868 75,877 62,904 45,005 40,275 8,216 7,581 4,483 5,528 893 1,041 102 301,819 North Carolina 0 0 0 4,214 3,766 181 2,590 9,008 8,358 5,888 6,011 0 0 0 0 40,016 Total 0 47,945 111,793 173,036 292,482 396,725 360,440 286,449 136,095 74,025 68,051 30,562 17,541 9,022 8,149 2,012,314 Table D7. Total Atlantic Coast striped bass recreational discard losses in numbers at age by state, 2001.
Age State 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Maine 110 3,858 20,848 17,224 13,401 5,883 3,955 3,443 554 134 134 51 32 11 4 69,639 New Hampshire 0 654 2,054 2,800 2,843 1,587 1,268 1,303 279 104 124 67 50 12 0 13,147 Massachusetts 0 6,233 27,455 75,063 89,902 74,347 69,146 60,716 16,978 4,439 4,725 1,979 1,320 258 310 432,872 Rhode Island 0 870 2,103 1,090 5,960 7,839 5,788 4,159 844 489 478 304 181 54 38 30,197 Connecticut 3,367 14,178 10,722 8,064 26,053 8,950 4,608 5,051 3,633 620 1,063 1,152 443 177 532 88,617 New York 276 5,567 11,569 6,884 14,025 10,683 7,969 4,999 1,128 703 590 184 283 85 134 65,073 New Jersey 99 3,824 5,415 14,468 28,558 13,500 6,373 2,820 1,195 522 343 88 42 14 0 77,262 Delaware 0 13 437 568 2,444 2,457 3,500 3,516 725 262 438 342 74 40 0 14,816 Maryland 25,426 62,527 77,792 30,745 19,194 4,643 6,072 2,974 883 466 165 146 94 34 43 231,204 Virgina 5,463 13,434 16,714 6,606 4,124 998 1,305 639 190 100 35 31 20 7 9 49,676 North Carolina 0 0 6 290 1,366 828 555 553 246 94 58 0 0 0 9 4,006 Total 34,741 111,159 175,115 163,803 207,871 131,714 110,540 90,174 26,655 7,933 8,154 4,346 2,541 693 1,079 1,076,508 36th SAW Consensus Summary 407
Table D8. Atlantic Coast striped bass commercial landings in numbers at age, 1982-2001.
Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total 1982 0 45,129 200,221 117,158 22,927 5,035 3,328 2,861 1,871 4,407 5,837 7,639 2,509 2,810 6,898 428,630 1983 0 54,348 120,639 120,999 38,278 7,416 1,954 677 607 1,690 1,314 2,375 2,656 1,856 2,733 357,541 1984 0 478,268 270,140 55,598 30,580 21,688 6,441 1,744 1,020 771 146 279 1,096 1,042 2,058 870,871 1985 0 53,699 45,492 7,545 9,448 19,248 21,569 6,581 3,692 1,514 466 607 493 894 3,373 174,621 1986 0 639 6,020 3,207 180 703 1,425 1,199 546 182 105 220 288 963 2,004 17,681 1987 0 0 3,087 4,265 1,618 252 1,104 1,075 448 233 95 273 302 235 565 13,552 1988 0 0 2,086 3,961 15,491 6,469 2,803 539 541 218 266 108 250 41 537 33,310 1989 0 0 0 0 0 139 1,111 959 1,007 631 475 164 343 444 2,129 7,402 1990 0 650 12,551 48,024 29,596 15,122 3,111 2,357 1,147 519 272 130 428 322 1,407 115,636 1991 0 2,082 22,430 44,723 41,048 21,614 8,546 4,412 4,816 1,163 269 125 80 553 1,937 153,798 1992 0 640 32,277 58,009 46,661 41,581 22,186 11,514 8,746 6,314 1,062 464 169 346 745 230,714 1993 0 1,848 21,073 93,868 87,447 42,112 32,485 13,829 8,396 6,420 3,955 763 184 76 404 312,860 1994 0 1,179 22,873 71,614 101,512 48,269 28,530 14,886 8,902 5,323 2,513 1,250 198 68 326 307,443 1995 0 6,726 35,190 114,519 134,709 98,471 38,918 34,191 37,324 21,827 8,364 3,166 997 363 149 534,914 1996 0 557 50,102 127,825 179,031 161,361 120,693 51,995 29,907 18,864 11,663 9,674 2,264 1,134 1,449 766,518 1997 0 335 96,860 293,511 225,218 201,397 103,129 60,000 33,262 18,888 11,811 7,861 2,753 2,178 978 1,058,181 1998 0 3,122 65,861 209,898 526,183 192,473 70,124 59,604 44,017 25,365 14,592 5,878 3,837 1,387 1,487 1,223,828 1999 0 7,344 93,998 233,720 275,305 235,925 76,755 47,252 54,777 35,387 24,006 9,883 6,832 1,836 795 1,103,812 2000 0 0 50,392 217,214 308,615 183,048 127,913 56,940 38,767 42,264 15,849 5,434 2,614 1,593 633 1,051,275 2001 0 165 86,190 189,602 240,736 138,678 86,825 92,095 33,367 31,165 21,960 12,759 4,962 2,564 665 941,733 408 36th SAW Consensus Summary
Table D9. Atlantic Coast striped bass commercial discard losses in numbers at age, 1982-2001.
age year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 total 1982 0 31,645 3,644 11,456 5,623 1,291 2,397 1,014 369 92 85 0 0 7 0 57,624 1983 0 24,067 1,453 2,878 7,761 2,311 610 610 262 174 0 0 0 0 0 40,127 1984 0 33,575 1,611 5,812 9,734 11,272 2,815 117 586 66 0 52 0 0 0 65,639 1985 0 7,728 30,472 5,939 10,891 3,395 2,742 1,045 261 131 131 0 0 0 0 62,734 1986 0 5,841 20,758 100,067 27,989 13,315 4,295 1,415 346 0 0 0 0 0 0 174,024 1987 0 4,206 14,382 28,597 51,389 16,940 6,520 1,319 1,011 395 111 86 111 0 0 125,066 1988 0 6,142 22,593 36,616 70,959 71,694 23,232 9,116 3,110 1,653 218 195 24 0 0 245,552 1989 0 13,854 50,240 49,029 83,396 82,757 33,479 15,502 6,342 705 1,409 1,409 663 41 0 338,827 1990 0 14,526 68,713 80,935 111,888 115,702 71,600 36,256 5,948 1,539 1,401 1,503 0 0 0 510,011 1991 79 12,632 37,009 64,210 77,335 56,894 36,912 24,857 6,610 4,071 6,542 16 0 0 0 327,167 1992 117 3,698 34,218 36,746 44,412 34,688 14,798 11,179 3,398 2,356 991 0 0 0 0 186,601 1993 0 7,449 50,160 79,011 95,116 63,487 20,941 15,351 9,270 4,606 1,651 536 260 0 0 347,839 1994 0 31,770 47,169 45,081 88,122 84,570 39,229 12,524 6,223 3,674 712 415 30 0 0 359,518 1995 0 72,822 75,520 53,551 94,158 121,592 61,447 19,083 7,569 4,269 2,290 2,346 807 0 0 515,454 1996 0 27,133 114,085 76,336 61,884 58,787 30,835 14,916 6,148 3,989 159 502 50 0 0 394,824 1997 476 7,108 64,352 61,871 30,602 20,951 14,002 6,592 1,963 4,309 2,658 801 1,060 0 0 216,743 1998 0 13,233 53,899 98,510 83,288 29,197 12,970 12,591 7,860 4,372 3,891 2,419 3,311 124 367 326,031 1999 984 58,076 49,894 43,744 55,740 14,477 5,213 3,704 1,980 1,304 648 612 240 3 0 236,620 2000 196 178,457 189,933 157,291 62,699 33,918 26,938 7,831 4,111 3,876 801 863 41 17 25 666,996 2001 0 2,638 58,079 77,958 88,808 29,410 18,877 11,613 9,664 6,371 4,778 1,957 737 10 0 310,900 36th SAW Consensus Summary 409
Table D10. Atlantic Coast striped bass recreational harvest and discard losses in numbers at age, 1982-2001.
age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15+ Total 1982 1,810 28,781 52,833 92,221 29,879 12,854 18,488 12,927 9,453 6,094 5,095 6,029 938 1,276 1,233 279,911 1983 3,625 31,912 56,144 69,265 103,980 29,559 16,149 2,837 2,026 1,845 3,267 3,269 2,220 2,203 1,880 330,182 1984 5,563 30,909 30,946 21,015 20,060 18,720 9,025 2,807 510 1,242 547 5 1,087 3,199 2,657 148,293 1985 1,311 11,102 25,995 26,999 38,364 20,464 19,211 9,658 2,397 1,760 447 220 29 23 5,509 163,489 1986 11,332 14,529 37,064 29,602 21,730 17,954 14,647 21,383 8,299 5,078 3,250 1,344 587 1,561 4,713 193,072 1987 1,368 6,709 20,160 18,560 14,254 7,849 5,580 4,096 4,925 2,355 1,242 1,608 2,889 1,851 6,963 100,408 1988 2,566 24,740 17,076 22,645 20,650 19,753 14,563 14,756 10,344 3,902 3,192 2,949 2,152 2,991 3,565 165,844 1989 729 22,140 29,416 19,216 21,499 12,542 11,055 4,565 3,074 2,422 1,350 392 909 1,122 3,196 133,626 1990 2,123 31,055 43,205 58,871 31,731 34,344 29,368 29,259 13,600 5,198 3,388 1,874 3,521 3,075 4,918 295,530 1991 1,713 58,121 85,813 99,784 43,567 22,929 45,853 53,651 47,331 18,855 7,362 2,613 2,544 2,751 14,465 507,353 1992 2,797 41,431 133,156 94,464 86,059 33,254 25,436 45,087 46,239 36,112 7,248 3,606 1,554 4,579 8,549 569,572 1993 287 60,335 114,073 154,451 105,949 79,780 33,126 38,157 64,920 65,119 35,527 8,028 4,109 1,097 11,327 776,285 1994 5,655 112,473 278,783 173,947 178,115 99,550 67,673 59,288 84,757 71,964 32,788 20,638 3,131 1,455 9,417 1,199,634 1995 3,838 347,272 348,369 279,759 162,474 250,606 104,445 137,595 106,747 62,459 41,591 10,943 7,720 1,562 3,310 1,868,692 1996 465 64,983 475,768 430,833 292,853 237,424 285,000 141,528 104,054 44,865 30,222 34,487 11,419 3,253 1,052 2,158,205 1997 2,057 278,024 325,236 494,939 360,153 371,499 288,376 305,724 165,092 97,283 45,173 21,325 8,470 5,596 3,816 2,772,763 1998 26,421 167,050 365,650 398,264 515,548 289,268 197,340 192,807 163,616 84,105 76,586 36,875 25,688 13,375 15,918 2,568,510 1999 8,162 50,834 287,988 377,852 320,364 463,488 254,502 175,799 136,715 101,802 72,950 34,535 18,610 11,174 6,196 2,320,972 2000 37,743 145,384 177,411 611,244 648,639 563,116 583,058 246,999 117,697 95,309 42,948 22,994 12,530 6,580 6,710 3,318,362 2001 34,741 159,104 286,908 336,838 500,352 528,438 470,980 376,624 162,750 81,958 76,205 34,909 20,081 9,715 9,219 3,088,822 410 36th SAW Consensus Summary
Table D11. Total Atlantic Coast striped bass catch in numbers at age, including scientific sampling, estimated commercial and recreational discard losses, 1982-2001.
Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total 1982 1,810 105,555 256,699 220,835 58,429 19,180 24,213 16,802 11,692 10,593 11,017 13,668 3,447 4,093 8,131 766,165 1983 3,625 110,327 178,236 193,141 150,019 39,286 18,713 4,125 2,895 3,709 4,581 5,644 4,876 4,059 4,613 727,849 1984 5,563 542,751 302,698 82,425 60,374 51,680 18,280 4,668 2,117 2,078 693 336 2,183 4,241 4,715 1,084,802 1985 1,311 72,529 101,959 40,483 58,703 43,106 43,522 17,283 6,351 3,404 1,043 827 522 917 8,882 400,844 1986 11,332 21,009 63,841 132,875 49,899 31,972 20,367 23,997 9,191 5,260 3,355 1,564 875 2,524 6,717 384,778 1987 1,368 10,915 37,629 51,422 67,260 25,041 13,204 6,490 6,384 2,982 1,448 1,968 3,302 2,086 7,528 239,026 1988 2,566 30,882 41,755 63,222 107,100 97,917 40,598 24,411 13,995 5,773 3,676 3,251 2,426 3,032 4,102 444,706 1989 729 35,994 79,655 68,244 104,896 95,437 45,645 21,026 10,423 3,758 3,234 1,965 1,915 1,608 5,325 479,855 1990 2,123 46,231 124,469 187,830 173,215 165,168 104,079 67,871 20,695 7,256 5,061 3,507 3,949 3,397 6,325 921,176 1991 1,792 72,836 145,252 208,716 161,950 101,438 91,311 82,920 58,757 24,090 14,173 2,755 2,624 3,304 16,402 988,318 1992 2,914 45,769 199,651 189,219 177,132 109,523 62,419 67,781 58,384 44,782 9,301 4,070 1,723 4,925 9,294 986,887 1993 287 69,633 185,306 327,330 288,512 185,379 86,551 67,337 82,587 76,145 41,133 9,327 4,553 1,173 11,731 1,436,983 1994 5,655 145,422 348,825 290,641 367,749 232,389 135,432 86,698 99,882 80,962 36,013 22,302 3,359 1,523 9,743 1,866,595 1995 3,838 426,821 459,079 447,829 391,341 470,669 204,809 190,869 151,640 88,555 52,246 16,455 9,524 1,925 3,459 2,919,060 1996 465 92,673 639,954 634,993 533,768 457,572 436,529 208,439 140,109 67,719 42,043 44,663 13,733 4,387 2,501 3,319,547 1997 2,533 285,466 486,449 850,321 615,973 593,847 405,508 372,316 200,317 120,479 59,642 29,987 12,282 7,774 4,794 4,047,687 1998 26,421 183,404 485,409 706,672 1,125,019 510,938 280,434 265,002 215,493 113,842 95,070 45,172 32,836 14,886 17,771 4,118,368 1999 9,210 116,452 433,400 656,249 651,804 714,112 336,562 226,801 193,497 138,519 97,623 45,054 25,687 13,018 6,991 3,664,980 2000 37,977 323,937 419,860 989,188 1,021,208 780,437 738,105 311,870 160,636 141,488 59,631 29,301 15,191 8,190 7,370 5,044,390 2001 34,741 159,284 373,435 527,397 741,748 667,237 557,868 468,775 196,167 113,175 98,186 47,677 25,046 12,280 9,883 4,343,798 36th SAW Consensus Summary 411
Table D12. Mean weight at age (kg) 1982-2001.
Age Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1982 0.13 0.64 1.09 1.54 2.42 3.75 4.83 5.79 6.20 8.68 10.80 11.20 12.97 13.26 15.91 1983 0.20 0.55 0.94 1.37 2.37 3.29 3.77 5.36 6.01 8.10 9.57 10.39 11.11 11.10 11.12 1984 0.24 0.60 1.69 1.62 2.67 3.39 5.07 5.65 6.76 7.76 8.41 12.65 10.65 11.75 14.75 1985 0.06 0.61 1.07 1.66 2.19 3.59 4.91 5.46 6.77 7.45 9.00 10.69 11.42 14.34 15.98 1986 0.14 0.57 1.27 2.40 2.44 3.12 3.95 5.05 5.44 6.09 7.75 9.16 10.97 11.55 15.83 1987 0.20 0.77 1.41 2.11 2.50 2.91 3.61 4.74 5.52 6.49 7.77 9.78 11.38 11.62 16.46 1988 0.31 0.91 1.10 1.98 3.12 4.02 4.38 4.70 5.24 5.62 8.58 10.40 11.50 11.31 17.00 1989 0.16 0.83 1.22 2.23 3.06 4.53 5.37 6.23 6.04 8.68 8.94 9.74 13.04 9.93 17.11 1990 0.08 0.89 1.14 2.05 2.35 3.83 4.91 5.96 5.70 5.97 7.44 9.08 9.36 10.80 17.65 1991 0.21 0.92 1.29 2.17 2.62 3.17 4.81 5.64 6.46 6.24 9.46 8.30 9.62 15.96 17.09 1992 0.10 0.69 1.31 1.93 2.81 3.67 4.90 5.79 6.96 8.15 9.77 12.44 13.10 11.15 17.65 1993 0.07 0.76 1.31 1.99 2.77 3.58 4.80 6.11 7.03 8.01 9.53 10.76 14.45 13.85 15.36 1994 0.24 1.05 1.69 2.21 2.85 3.50 4.94 6.20 6.80 7.53 9.73 10.69 11.38 9.06 17.75 1995 0.28 0.70 1.35 2.18 2.77 3.65 5.38 6.16 7.27 8.86 7.57 9.73 13.97 15.65 20.37 1996 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 1997 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 1998 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 1999 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 2000 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 2001 0.14 1.05 1.47 2.32 3.23 4.52 6.39 7.11 7.81 9.20 9.31 10.10 11.36 12.45 17.30 412 36th SAW Consensus Summary
Table D13. Estimated parameter values and associated SE, T statistic and CV from ADAPT 12+ run prior to re-weighting.
T-PAR. EST. STD.ERR T-STATISTIC C.V. PAR. EST. STD.ERR STATISTIC C.V.
N 1 1.73E+04 8.72E+03 1.99E+00 0.5 q NYOHS6 2.60E-04 6.65E-05 3.90E+00 0.26 N 2 1.29E+04 4.95E+03 2.62E+00 0.38 q NYOHS7 5.47E-04 1.40E-04 3.90E+00 0.26 N 3 6.61E+03 2.04E+03 3.23E+00 0.31 q NYOHS8 7.92E-04 2.04E-04 3.89E+00 0.26 N 4 4.77E+03 1.32E+03 3.63E+00 0.28 q NYOHS9 1.27E-03 3.27E-04 3.88E+00 0.26 N 5 3.80E+03 9.64E+02 3.95E+00 0.25 q NYOHS10 2.13E-03 5.50E-04 3.88E+00 0.26 N 6 4.96E+03 1.20E+03 4.13E+00 0.24 q NYOHS11 2.74E-03 7.32E-04 3.74E+00 0.27 N 7 2.93E+03 7.40E+02 3.95E+00 0.25 q NYOHS12+ 2.68E-03 6.89E-04 3.88E+00 0.26 N 8 1.52E+03 4.17E+02 3.65E+00 0.27 q NEFSC2 5.10E-05 1.94E-05 2.63E+00 0.38 N 9 1.61E+03 4.30E+02 3.75E+00 0.27 q NEFSC3 5.69E-05 1.64E-05 3.48E+00 0.29 N 10 4.57E+02 1.38E+02 3.32E+00 0.3 q NEFSC4 9.24E-05 2.54E-05 3.63E+00 0.28 N 11 2.86E+02 8.60E+01 3.33E+00 0.3 q NEFSC5 1.33E-04 3.30E-05 4.04E+00 0.25 q MACOM7 5.73E-04 1.64E-04 3.49E+00 0.29 q NEFSC6 2.52E-04 6.24E-05 4.04E+00 0.25 q MACOM8 8.32E-04 2.39E-04 3.48E+00 0.29 q NEFSC7 3.89E-04 9.66E-05 4.03E+00 0.25 q MACOM9 1.46E-03 4.19E-04 3.48E+00 0.29 q NEFSC8 6.62E-04 1.60E-04 4.14E+00 0.24 q MACOM10 1.94E-03 5.57E-04 3.48E+00 0.29 q NEFSC9 9.02E-04 2.25E-04 4.01E+00 0.25 q MACOM11 2.57E-03 7.38E-04 3.48E+00 0.29 q NEFSC10 1.51E-03 3.88E-04 3.89E+00 0.26 q MACOM12+ 2.72E-03 7.80E-04 3.48E+00 0.29 q NEFSC11 1.88E-03 5.40E-04 3.48E+00 0.29 q CTCPUE3 1.73E-04 3.84E-05 4.52E+00 0.22 q NEFSC12+ 2.69E-03 8.02E-04 3.36E+00 0.3 q CTCPUE4 2.39E-04 5.17E-05 4.63E+00 0.22 q HUDSHD8:12 2.76E-04 6.64E-05 4.16E+00 0.24 q CTCPUE5 3.54E-04 7.64E-05 4.63E+00 0.22 q YOYNY1 1.12E-04 2.45E-05 4.57E+00 0.22 q CTCPUE6 4.86E-04 1.05E-04 4.63E+00 0.22 q YOYNJ1 7.95E-05 1.79E-05 4.45E+00 0.22 q CTCPUE7 7.33E-04 1.59E-04 4.62E+00 0.22 q YOYMD1 8.57E-05 1.88E-05 4.57E+00 0.22 q CTCPUE8 9.35E-04 2.03E-04 4.61E+00 0.22 q YOYVA1 1.09E-04 2.38E-05 4.57E+00 0.22 q CTCPUE9 1.52E-03 3.30E-04 4.61E+00 0.22 q YRLLI2 1.18E-04 2.87E-05 4.13E+00 0.24 q CTCPUE10 2.74E-03 5.95E-04 4.61E+00 0.22 q YRLMD2 1.26E-04 2.81E-05 4.49E+00 0.22 q CTCPUE11 3.30E-03 7.53E-04 4.38E+00 0.23 q NJTRL2:12 2.12E-05 5.63E-06 3.77E+00 0.27 q CTCPUE12+ 1.06E-03 2.30E-04 4.61E+00 0.22 q CTTRL4:06 6.49E-05 1.56E-05 4.16E+00 0.24 q MDSSN3 1.60E-04 3.75E-05 4.27E+00 0.23 q DETRWL2:07 2.42E-05 6.92E-06 3.50E+00 0.29 q MDSSN4 2.12E-04 4.96E-05 4.28E+00 0.23 q VAPN1 8.43E-05 4.14E-05 2.04E+00 0.49 q MDSSN5 2.75E-04 6.41E-05 4.28E+00 0.23 q VAPN2 6.41E-05 1.93E-05 3.33E+00 0.3 q MDSSN6 3.82E-04 8.92E-05 4.28E+00 0.23 q VAPN3 8.77E-05 2.63E-05 3.34E+00 0.3 q MDSSN7 5.47E-04 1.28E-04 4.27E+00 0.23 q VAPN4 1.28E-04 3.81E-05 3.35E+00 0.3 q MDSSN8 6.35E-04 1.53E-04 4.14E+00 0.24 q VAPN5 2.12E-04 6.34E-05 3.35E+00 0.3 q MDSSN9 8.34E-04 1.96E-04 4.26E+00 0.23 q VAPN6 1.50E-04 4.46E-05 3.35E+00 0.3 q MDSSN10 1.24E-03 3.11E-04 4.01E+00 0.25 q VAPN7 5.48E-04 1.64E-04 3.35E+00 0.3 q MDSSN11 2.33E-03 6.22E-04 3.75E+00 0.27 q VAPN8 7.96E-04 2.38E-04 3.34E+00 0.3 q MDSSN12+ 1.86E-03 4.36E-04 4.26E+00 0.23 q VAPN9 1.06E-03 3.17E-04 3.34E+00 0.3 q NYOHS3 1.10E-04 2.84E-05 3.89E+00 0.26 q VAPN10 1.55E-03 4.65E-04 3.34E+00 0.3 q NYOHS4 1.36E-04 3.48E-05 3.90E+00 0.26 q VAPN11 2.38E-03 7.46E-04 3.19E+00 0.31 q NYOHS5 1.98E-04 5.08E-05 3.91E+00 0.26 q VAPN12+ 1.81E-03 5.99E-04 3.02E+00 0.33 36th SAW Consensus Summary 413
Table D14. Fishing mortality for several age intervals in 12+ and 13+ runs.
Average F for Ages 4,11 4,10 3,8 8,11 7,10 Year 13+ 12+ 13+ 12+ 13+ 12+
1982 0.43 0.41 0.31 0.34 0.60 0.54 1983 0.40 0.30 0.29 0.25 0.44 0.27 1984 0.15 0.15 0.21 0.18 0.09 0.12 1985 0.17 0.15 0.19 0.15 0.12 0.17 1986 0.15 0.13 0.15 0.11 0.17 0.16 1987 0.07 0.05 0.06 0.04 0.08 0.06 1988 0.13 0.10 0.10 0.07 0.17 0.12 1989 0.08 0.06 0.07 0.06 0.10 0.06 1990 0.13 0.10 0.12 0.09 0.12 0.08 1991 0.14 0.10 0.10 0.08 0.19 0.11 1992 0.11 0.08 0.08 0.07 0.13 0.09 1993 0.15 0.11 0.10 0.08 0.20 0.12 1994 0.16 0.12 0.10 0.09 0.21 0.15 1995 0.20 0.18 0.15 0.13 0.25 0.21 1996 0.21 0.18 0.19 0.17 0.22 0.19 1997 0.27 0.23 0.23 0.21 0.30 0.25 1998 0.27 0.21 0.20 0.17 0.32 0.23 1999 0.28 0.21 0.18 0.16 0.38 0.27 2000 0.29 0.24 0.24 0.21 0.33 0.27 2001 0.32 0.24 0.22 0.19 0.40 0.29 1999-2001 Average 0.30 0.23 0.21 0.19 0.37 0.28 Table D15. Fishing mortality at age in 2001 for 12+ and 13+ group runs.
Age 1 2 3 4 5 6 7 8 9 10 11 12 13 Plus Group 13+ 0 0.03 0.06 0.16 0.16 0.25 0.34 0.35 0.41 0.44 0.41 0.34 0.34 12+ 0 0.02 0.06 0.14 0.15 0.21 0.29 0.28 0.3 0.3 0.29 0.29 414 36th SAW Consensus Summary
Table D16. Back-calculated partial recruitment and 1996-2001 average PR from 12+ run.
Age 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 97-01 av 1 0 0 0.01 0 0.02 0.01 0 0 0 0 0 0 0 0 0 0 0.01 0 0.02 0.01 0 2 0.11 0.15 0.54 0.1 0.03 0.06 0.06 0.1 0.07 0.08 0.07 0.07 0.1 0.13 0.04 0.08 0.05 0.05 0.12 0.08 0.11 3 0.44 0.33 1 0.16 0.13 0.2 0.11 0.39 0.26 0.2 0.39 0.2 0.33 0.27 0.26 0.19 0.17 0.13 0.26 0.19 0.44 4 0.44 0.78 0.37 0.23 0.31 0.35 0.16 0.48 0.74 0.43 0.5 0.45 0.32 0.4 0.53 0.32 0.36 0.28 0.45 0.45 0.44 5 0.28 0.69 0.7 0.42 0.44 0.54 0.37 0.74 1 0.65 0.71 0.55 0.54 0.39 0.69 0.52 0.6 0.41 0.72 0.48 0.28 6 0.2 0.38 0.66 0.89 0.36 0.77 0.41 0.94 0.96 0.61 0.9 0.54 0.47 0.68 0.67 0.84 0.65 0.51 0.88 0.66 0.2 7 0.37 0.37 0.43 1 0.73 0.51 0.66 0.53 0.84 0.55 0.76 0.52 0.42 0.39 1 0.62 0.62 0.58 0.96 0.93 0.37 8 0.89 0.12 0.22 0.67 1 0.85 0.48 1 0.63 0.69 0.82 0.6 0.56 0.57 0.56 1 0.61 0.69 1 0.9 0.89 9 1 0.39 0.13 0.46 0.59 1 1 0.58 0.81 0.55 1 0.74 1 1 0.61 0.55 1 0.61 0.92 0.97 1 10 0.53 1 0.72 0.32 0.62 0.68 0.48 0.8 0.32 1 0.84 1 0.82 0.95 0.72 0.54 0.46 1 0.81 1 0.53 11 0.33 0.52 0.56 0.62 0.5 0.6 0.43 0.75 0.88 0.62 0.8 0.57 0.53 0.52 0.71 0.67 0.64 0.51 0.85 0.82 0.33 12 0.33 0.52 0.56 0.62 0.5 0.6 0.43 0.75 0.88 0.62 0.8 0.57 0.53 0.52 0.71 0.67 0.64 0.51 0.85 0.82 0.33 Table D17. Estimated population abundance, thousands at age, 1982-2002.
Age 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 1 1,733 4,264 3,431 3,643 3,038 3,703 5,627 6,863 7,690 7,776 7,674 9,035 14,803 11,212 12,509 14,225 8,536 11,442 8,381 15,558 17,967 2 1,402 1,490 3,666 2,948 3,135 2,604 3,186 4,841 5,906 6,617 6,691 6,603 7,776 12,736 9,646 10,766 12,241 7,322 9,840 7,179 13,359 3 953 1,109 1,180 2,652 2,470 2,679 2,232 2,713 4,133 5,040 5,628 5,716 5,618 6,558 10,566 8,217 9,002 10,366 6,194 8,169 6,029 4 817 582 789 735 2,188 2,067 2,271 1,882 2,261 3,442 4,204 4,659 4,748 4,512 5,219 8,500 6,621 7,297 8,520 4,942 6,631 5 319 498 322 603 595 1,760 1,731 1,896 1,557 1,772 2,769 3,443 3,706 3,817 3,468 3,903 6,527 5,043 5,672 6,416 3,692 6 144 220 290 221 464 466 1,453 1,391 1,534 1,179 1,375 2,219 2,695 2,849 2,922 2,490 2,788 4,574 3,736 3,935 4,751 7 104 107 153 201 150 370 377 1,159 1,108 1,167 921 1,082 1,738 2,104 2,015 2,091 1,592 1,925 3,275 2,491 2,740 8 36 67 74 115 133 110 306 287 956 857 920 735 851 1,370 1,621 1,330 1,423 1,110 1,345 2,134 1,609 9 23 16 54 60 83 92 89 241 228 759 661 729 570 652 1,002 1,202 799 979 745 868 1,391 10 34 9 11 45 45 63 73 64 198 177 599 515 551 398 420 733 849 488 663 492 556 11 53 19 4 7 35 34 51 58 51 163 130 474 372 399 260 299 519 625 291 440 313 12+ 140 80 74 79 122 351 178 193 173 289 279 308 381 239 403 274 602 579 292 415 550 10+ 227 108 89 131 202 448 302 315 422 629 1,008 1,297 1,304 1,036 1,083 1,306 1,970 1,692 1,246 1,347 1,419 8+ 286 191 217 306 418 650 697 843 1,606 2,245 2,589 2,761 2,725 3,058 3,706 3,838 4,192 3,781 3,336 4,349 4,419 1+ 5,758 8,461 10,048 11,309 12,458 14,299 17,574 21,588 25,795 29,238 31,851 35,518 43,809 46,846 50,051 54,030 51,499 51,750 48,954 53,039 59,588 36th SAW Consensus Summary 415
Table D18. Spawning stock biomass of female striped bass in metric tons at age and annual total in MT and millions of pounds (Mlb), 1982-2001.
Age 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 19 13 19 23 66 64 73 56 68 102 126 142 157 162 171 293 227 256 296 171 5 40 57 37 70 73 265 273 288 218 252 419 486 540 595 553 640 1,071 828 945 1,069 6 114 130 172 143 258 264 977 1,108 1,116 684 905 1,489 1,772 1,927 2,246 1,952 2,194 3,627 2,924 3,176 7 197 166 261 339 236 524 564 2,267 2,185 2,115 1,529 1,904 3,060 3,806 4,003 4,834 3,490 4,206 7,139 5,380 8 86 152 153 265 290 212 560 666 2,396 1,993 2,165 1,784 2,051 3,316 4,394 3,855 4,408 3,199 3,843 6,133 9 56 43 154 174 212 230 207 608 639 2,221 1,948 2,198 1,715 2,022 3,243 4,152 2,727 3,607 2,508 2,893 10 128 30 35 149 137 176 193 203 563 494 2,049 1,794 1,888 1,433 1,604 2,887 3,343 1,886 2,818 1,862 11 270 81 18 29 126 112 180 194 194 580 479 1,966 1,544 1,424 1,108 1,284 2,224 2,675 1,240 2,079 12 959 409 476 542 811 2,426 1,260 1,375 1,226 2,062 2,084 2,113 2,737 2,026 2,887 1,945 4,263 4,098 2,056 3,244 Total, MT 1,867 1,080 1,322 1,733 2,208 4,273 4,284 6,763 8,603 10,500 11,701 13,873 15,462 16,709 20,208 21,840 23,946 24,379 23,766 26,004 Total, Mlb 4.11 2.38 2.91 3.81 4.86 9.40 9.42 14.88 18.93 23.10 25.74 30.52 34.02 36.76 44.46 48.05 52.68 53.63 52.29 57.21 416 36th SAW Consensus Summary
Table D19. Estimates of bay-wide fishing mortality and ASMFC Target Fishing mortality estimates.
(Estimates include a non-harvest mortality of 0.10.)
Year Bay-wide F ASMFC target 1993 0.19 0.25 1994 0.20 0.25 1995 0.25 0.30 1996 0.33 0.30 1997 0.25 0.28 1998 0.21 0.28 1999 0.31 0.28 2000 0.28 0.28 2001 0.23 0.28 36th SAW Consensus Summary 417
Figure D1.Proportions of recreational and commercial fishery landings in numbers for 2001.
22% 25%
7%
46%
rec discards rec harvest com discards com harvest 418 36th SAW Consensus Summary
Figure D2. Recreational harvest in numbers of fish and weight (million lb) by state for 2001.
600,000 500,000 400,000
- fish 300,000 200,000 100,000 0
NH NC DE CT ME RI NY MA VA MD NJ 6.00 5.00 4.00 million lb 3.00 2.00 1.00 0.00 NH ME DE CT NC RI MD VA NY MA NJ 36th SAW Consensus Summary 419
Figure D3. Total losses (harvest and dead discards) for recreational fishery in 1982-2001.
6,000 5,000 4,000 thousand fish 3,000 2,000 1,000 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year Figure D4. Recreational and commercial catch (harvest and discard) in number in 2000 and 2001.
1,200,000 1,000,000 800,000
- fish 600,000 400,000 200,000 0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 age 2000 2001 420 36th SAW Consensus Summary
Figure D5. Maryland Spawning Stock Index, ages 2-12+, 1985-2001.
1200 1000 800 cpue 600 400 200 0
1985 1987 1989 1991 1993 1995 1997 1999 2001 year Figure D6. New York Ocean Haul Seine, Total CPUE ages 5-12+, 1987-2001.
160 140 120 100 cpue 80 60 40 20 0
1987 1989 1991 1993 1995 1997 1999 2001 Year 36th SAW Consensus Summary 421
Figure D7. NMFS/NEFSC trawl survey CPUE Ages 2-12+, 1983-2002.
1.6 1.4 1.2 mean catch per tow 1.0 0.8 0.6 0.4 0.2 0.0 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 year Figure D8. Virginia Rappahannock River Pound Net CPUE, 1991-2002.
45 40 35 30 25 cpue 20 15 10 5
0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 year 422 36th SAW Consensus Summary
Figure D9. Age aggregated trawl CPUE, Delaware, New Jersey, and Connecticut, 1984-2002.
10 9
8 7
6 cpue 5 4
3 2
1 0
1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year CT trawl DE trawl NJ trawl Figure D10. Indices of young of the year abundance for the Chesapeake Stock, Maryland and Virginia surveys, 1981-2001.
25.00 20.00 15.00 cpue 10.00 5.00 0.00 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 year MD VA 36th SAW Consensus Summary 423
Figure D11. Young of the year survey values for the Hudson (NY) and Delaware Bay (DE, NJ) stocks, 1981-2001.
40 2.5 35 2
30 Hudson CPUE DE and NJ 25 1.5 20 15 1 10 0.5 5
0 0 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 year hudson NJ DE Figure D12. Indices of age-1 striped bass abundance for Long Island and Maryland.
2.5 2
1.5 cpue 1
0.5 0
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year MD NYLI 424 36th SAW Consensus Summary
Figure D13. Massachusetts total age 8-12+ CPUE, 1990-2001.
2.50 2.00 number per hour fished 1.50 1.00 0.50 0.00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 year Figure D14. Connecticut total ages 2-12+ CPUE, 1981-2001.
9.00 8.00 7.00 number per trip 6.00 5.00 4.00 3.00 2.00 1.00 0.00 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 Year 36th SAW Consensus Summary 425
Figure D15. Hudson River shad bycatch indices of striped bass abundance, 1985-2001.
3,000 2,500 number per set 2,000 1,500 1,000 500 0
1985 1987 1989 1991 1993 1995 1997 1999 2001 year Figure D16. Striped bass fishing mortality from the 2001 ADAPT for age 4 through 10 for 12+ run and 4 through 11 for 13+ run.
0.45 0.40 0.35 0.30 average F 0.25 0.20 0.15 0.10 0.05 0.00 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year 13+ 4,11 12+ 4,10 426 36th SAW Consensus Summary
Figure D17. Striped bass fishing mortality from the 2001 ADAPT for ages 7-10 (12+ run) and 8-11 (13+
run).
0.70 0.60 0.50 average F 0.40 0.30 0.20 0.10 0.00 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year 13+ 12+
Figure D18. Striped bass fishing mortality from the 2001 ADAPT for ages 3 through 8 for 12+ and 13+ runs.
0.40 0.35 0.30 average F 0.25 0.20 0.15 0.10 0.05 0.00 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year 13+ 12+
36th SAW Consensus Summary 427
Figure D19. Population size (ages 1-12+) estimates for 12+ and 13+ runs.
70 60 50
- fish, million 40 30 20 10 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year 13+ 12+
Figure D20. Recruitment (Age 1) for 12+ and 13+ runs.
20 18 16
- fish, million 14 12 10 8
6 4
2 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 year 13+ 12+
428 36th SAW Consensus Summary
Figure D21. Female spawning stock biomass for 12+ and 13+ runs.
30,000 25,000 20,000 SSB, mt 15,000 10,000 5,000 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 year 12+ 13+
Figure D22. Terminal full F distribution (ages 7-10) based on 500 bootstrap iterations> 80 % confidence intervals are shown by dashed lines.
16 100 14 90 80 Cumulative Percentage 12 70 Percentage 10 60 8 50 6 40 30 4
20 2 10 0 0 0.20 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.40 Fishing Mortality 36th SAW Consensus Summary 429
Figure D23. Population size (1+) estimates distribution in 2001 based on 500 bootstrap iterations> 80 %
confidence intervals are shown by dashed lines.
18 100 16 90 Cumulative Percentage 14 80 70 12 Percentage 60 10 50 8
40 6
30 4 20 2 10 0 0 40 45 50 55 60 65 70 75 80 85 90 Abundance (million) 430 36th SAW Consensus Summary
Tagging Segment Tables Table D20. Time series of instantaneous fishing mortality estimates (F) adjusted for live release bias. Results are for Striped bass >= 18 inches. Reporting Rate (DE) = 0.433.
Coast Programs*
Year MADFW NYOHS NJDEL NCCOOP 1988 0.28 -0.08 1989 -0.26 -0.23 0.34 1990 0.28 -0.17 0.35 1991 0.00 0.25 0.20 1992 -0.02 -0.18 0.19 -0.08 1993 0.00 0.50 0.30 0.01 1994 -0.01 0.12 0.20 0.39 1995 0.07 -0.16 -0.13 -0.16 1996 0.03 0.13 -0.03 0.46 1997 0.08 0.19 0.35 0.46 1998 0.05 0.54 0.02 0.45 1999 0.07 0.20 0.15 -0.06 2000 0.04 0.39 0.14 0.80 2001 -0.02 0.57 0.14 0.50 Producer Area Programs Weighted**
Year DE/PA MDCB VARAP Average 1987 0.09 1988 0.06 1989 -0.08 1990 0.22 -0.09 1991 0.21 1.01 1992 0.18 -0.08 1993 0.16 0.23 0.26 0.22 1994 0.11 0.21 0.29 0.20 1995 0.12 0.21 0.17 0.20 1996 0.18 0.25 0.32 0.25 1997 0.22 0.32 0.41 0.31 1998 0.24 0.38 0.70 0.37 1999 0.3 0.45 0.89 0.43 2000 0.33 0.47 0.75 0.46 2001 0.33 0.55 1.20 0.53
- A coastal unweighted average of F for striped bass >= 18 inches was not provided because MADFW primarily represents fish larger than 28 inches and GOF bootstrap indicated a lack of fit for the full parameterized models of NYOHS and NCCOOP.
VARAP was excluded from the producer area weighted average because a GOF bootstrap analysis indicated a lack of fit for the full parameterized model.
36th SAW Consensus Summary 431
Table D21. Time series of instantaneous fishing mortality estimates (F) adjusted for live release bias. Results are for Striped bass >= 28 inches. Reporting Rate (DE) = 0.43.
Coast Programs Unweighted*
Year MADFW NYOHS NJDEL NCCOOP Average 1988 -0.20 -0.02 -0.20 **
1989 -0.16 -0.10 0.10 -0.13 **
1990 0.16 -0.25 0.08 -0.05 **
1991 0.15 -0.09 0.03 0.03 1992 -0.02 0.10 0.20 0.03 0.09 1993 -0.01 0.17 0.18 0.03 0.11 1994 -0.01 0.17 0.10 0.07 0.09 1995 0.10 0.11 0.07 0.12 0.09 1996 0.09 0.15 0.10 0.27 0.11 1997 0.11 0.17 0.19 0.24 0.16 1998 0.08 0.22 0.16 0.22 0.15 1999 0.10 0.20 0.12 0.24 0.14 2000 0.08 0.08 0.22 0.22 0.13 2001 -0.02 0.10 0.18 0.22 0.09 Producer Area Programs Weighted***
Year DE/PA MDCB VARAP Average 1988 -0.13 1989 -0.16 1990 0.23 0.19 1991 0.10 0.18 1992 0.11 0.13 1993 -0.10 0.13 0.22 1994 -0.07 0.11 0.25 1995 0.26 0.21 0.29 0.21 1996 0.26 0.22 0.35 0.22 1997 0.30 0.23 0.33 0.23 1998 0.34 0.25 0.27 0.26 1999 0.40 0.24 0.31 0.26 2000 0.37 0.12 0.24 0.15 2001 0.43 0.13 0.24 0.16
- NCCOOP was excluded from the coastal weighted average because a GOF bootstrap analysis indicated a lack of fit for the full parameterized model.
- - Total mortality estimates (Z) at or below Natural mortality estimate of 0.15.
- VARAP was excluded from the producer area weighted average because a GOF bootstrap analysis indicated a lack of fit for the full parameterized model.
432 36th SAW Consensus Summary
Table D22. Survival (S) and fishing mortality (F) rates of striped bass >= 18 inches including estimates adjusted (adj.) for reporting rate (0.433), bias from live releases, and hooking mortality (0.08).
Coast Programs Massachusetts C-hat adjustment = 1.727; bootstrap GOF probability = 0.44 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1992 0.798 0.076 0.052 0.750 -0.094 0.880 -0.023 -0.119 0.084 1993 0.799 0.074 0.050 0.583 -0.071 0.860 0.000 -0.086 0.095 1994 0.798 0.076 0.058 0.558 -0.080 0.867 -0.008 -0.102 0.096 1995 0.751 0.136 0.052 0.527 -0.068 0.805 0.066 -0.006 0.144 1996 0.755 0.131 0.090 0.420 -0.100 0.839 0.026 -0.043 0.100 1997 0.762 0.122 0.061 0.278 -0.044 0.797 0.077 0.010 0.148 1998 0.766 0.117 0.074 0.323 -0.063 0.817 0.052 -0.014 0.122 1999 0.770 0.111 0.051 0.310 -0.040 0.802 0.070 0.005 0.141 2000 0.806 0.066 0.046 0.241 -0.028 0.829 0.037 -0.029 0.108 2001 0.846 0.017 0.038 0.358 -0.034 0.875 -0.017 -0.084 0.055 New York - Ocean Haul Seine bootstrap GOF probability < 0.002 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1988 0.550 0.448 0.075 0.930 -0.150 0.650 0.280 0.117 0.504 1989 0.904 -0.049 0.093 0.940 -0.190 1.121 -0.260 -0.287 -0.234 1990 0.564 0.423 0.072 0.830 -0.130 0.650 0.280 0.104 0.509 1991 0.755 0.131 0.077 0.710 -0.130 0.863 0.000 -0.164 0.321 1992 0.919 -0.066 0.070 0.690 -0.110 1.033 -0.180 -0.263 0.831 1993 0.484 0.576 0.056 0.610 -0.080 0.524 0.500 0.283 0.761 1994 0.683 0.231 0.065 0.720 -0.110 0.763 0.120 -0.026 0.334 1995 0.935 -0.083 0.062 0.550 -0.080 1.015 -0.160 -0.182 -0.141 1996 0.695 0.214 0.059 0.580 -0.080 0.755 0.130 -0.036 0.403 1997 0.652 0.278 0.061 0.600 -0.080 0.711 0.190 -0.017 0.534 1998 0.467 0.611 0.053 0.570 -0.070 0.502 0.540 0.274 0.885 1999 0.655 0.273 0.061 0.510 -0.070 0.706 0.200 -0.052 0.679 2000 0.546 0.455 0.049 0.570 -0.060 0.583 0.390 0.061 0.939 2001 0.454 0.640 0.056 0.510 -0.070 0.485 0.570 0.382 0.799 36th SAW Consensus Summary 433
New Jersey - Delaware Bay bootstrap GOF probability = 0.35 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1989 0.885 -0.028 0.106 0.743 -0.180 1.081 -0.230 -0.341 0.727 1990 0.797 0.077 0.120 0.794 -0.220 1.020 -0.170 -0.356 0.548 1991 0.573 0.407 0.088 0.722 -0.140 0.670 0.250 0.023 0.579 1992 0.622 0.325 0.078 0.711 -0.130 0.711 0.190 0.043 0.386 1993 0.558 0.433 0.081 0.652 -0.120 0.635 0.300 0.184 0.446 1994 0.626 0.318 0.083 0.579 -0.110 0.705 0.200 0.101 0.315 1995 0.847 0.016 0.096 0.582 -0.130 0.977 -0.130 -0.212 0.035 1996 0.759 0.126 0.113 0.527 -0.150 0.890 -0.030 -0.176 0.228 1997 0.530 0.485 0.089 0.616 -0.130 0.607 0.350 0.146 0.612 1998 0.715 0.185 0.124 0.488 -0.150 0.844 0.020 -0.118 0.229 1999 0.655 0.273 0.083 0.577 -0.110 0.738 0.150 0.024 0.328 2000 0.660 0.266 0.085 0.579 -0.120 0.746 0.140 -0.007 0.356 2001 0.648 0.284 0.093 0.617 -0.130 0.748 0.140 0.014 0.303 North Carolina - Cooperative Trawl Cruise probability < 0.001 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1988 0.909 -0.054 0.015 0.750 -0.027 0.933 -0.081 -0.105 -0.057 1989 0.604 0.354 0.010 0.720 -0.017 0.615 0.337 0.166 0.542 1990 0.556 0.437 0.057 0.583 -0.082 0.606 0.352 0.193 0.541 1991 0.615 0.336 0.077 0.693 -0.131 0.708 0.196 0.030 0.395 1992 0.814 0.056 0.090 0.531 -0.123 0.928 -0.075 -0.307 0.227 1993 0.757 0.129 0.072 0.647 -0.115 0.855 0.007 -0.211 0.286 1994 0.522 0.499 0.068 0.628 -0.105 0.584 0.389 0.220 0.592 1995 0.906 -0.052 0.080 0.523 -0.107 1.014 -0.164 -0.194 -0.134 1996 0.530 0.486 0.042 0.270 -0.028 0.545 0.457 0.240 0.735 1997 0.523 0.499 0.069 0.228 -0.042 0.546 0.456 0.180 0.838 1998 0.522 0.500 0.073 0.250 -0.048 0.548 0.451 0.167 0.849 1999 0.893 -0.037 0.065 0.150 -0.026 0.917 -0.063 -0.063 -0.063 2000 0.362 0.865 0.047 0.556 -0.064 0.387 0.798 0.540 1.149 2001 0.501 0.541 0.050 0.298 -0.038 0.521 0.503 0.271 0.805 434 36th SAW Consensus Summary
Producer Area Programs Delaware / Pennsylvania - Delaware River C-hat adjustment = 1.057; bootstrap GOF probability = 0.44 for the full parameterized model.
With trend models included:
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1993 0.660 0.270 0.100 0.390 -0.098 0.730 0.160 0.010 0.350 1994 0.660 0.270 0.110 0.550 -0.148 0.770 0.110 -0.060 0.300 1995 0.650 0.280 0.120 0.500 -0.151 0.770 0.120 -0.020 0.270 1996 0.630 0.310 0.110 0.440 -0.122 0.720 0.180 0.080 0.300 1997 0.620 0.330 0.080 0.420 -0.099 0.690 0.220 0.120 0.350 1998 0.590 0.380 0.110 0.470 -0.129 0.680 0.240 0.130 0.370 1999 0.570 0.410 0.090 0.470 -0.103 0.635 0.300 0.170 0.460 2000 0.550 0.450 0.100 0.460 -0.114 0.620 0.330 0.140 0.560 2001 0.540 0.470 0.095 0.560 -0.128 0.620 0.330 0.080 0.660 With trend models excluded:
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1993 0.670 0.250 0.100 0.390 -0.098 0.740 0.150 -0.020 0.350 1994 0.657 0.270 0.110 0.550 -0.148 0.770 0.110 -0.050 0.300 1995 0.610 0.340 0.120 0.500 -0.151 0.720 0.180 0.100 0.270 1996 0.600 0.360 0.110 0.440 -0.122 0.680 0.230 0.130 0.340 1997 0.620 0.330 0.080 0.420 -0.099 0.690 0.220 0.120 0.350 1998 0.590 0.380 0.110 0.470 -0.129 0.680 0.290 0.130 0.370 1999 0.610 0.340 0.090 0.470 -0.103 0.680 0.240 0.150 0.330 2000 0.610 0.340 0.100 0.460 -0.114 0.690 0.220 0.140 0.320 2001 0.615 0.340 0.095 0.560 -0.128 0.700 0.200 0.120 0.290 Maryland - Chesapeake Bay Spring Spawning Stock C-hat adjustment = 1.335; bootstrap GOF probability = 0.76 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1987 0.809 0.062 0.070 0.950 -0.145 0.946 -0.095 -0.188 0.060 1988 0.842 0.023 0.042 0.840 -0.077 0.911 -0.057 -0.104 0.006 1989 0.872 -0.014 0.034 0.930 -0.068 0.936 -0.084 -0.152 0.042 1990 0.638 0.299 0.055 0.580 -0.073 0.689 0.223 0.159 0.294 1991 0.635 0.303 0.082 0.450 -0.089 0.698 0.210 0.166 0.257 1992 0.630 0.312 0.111 0.430 -0.120 0.717 0.183 0.150 0.218 1993 0.626 0.319 0.089 0.380 -0.084 0.683 0.231 0.186 0.280 1994 0.622 0.325 0.100 0.430 -0.106 0.696 0.212 0.144 0.289 1995 0.626 0.318 0.117 0.320 -0.100 0.696 0.213 0.117 0.328 1996 0.601 0.359 0.110 0.350 -0.100 0.668 0.254 0.189 0.325 1997 0.575 0.403 0.114 0.270 -0.082 0.627 0.317 0.267 0.371 1998 0.544 0.458 0.111 0.250 -0.074 0.588 0.381 0.299 0.472 1999 0.519 0.506 0.109 0.200 -0.059 0.551 0.446 0.313 0.600 2000 0.490 0.563 0.095 0.360 -0.086 0.537 0.473 0.281 0.707 2001 0.463 0.620 0.082 0.330 -0.066 0.496 0.551 0.298 0.876 36th SAW Consensus Summary 435
Virginia - Rappahannock River C-hat adjustment = 1.377; bootstrap GOF probability = 0.18 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1990 0.810 0.060 0.111 0.481 -0.143 0.945 -0.094 -0.282 0.138 1991 0.287 1.098 0.063 0.524 -0.082 0.313 1.012 0.711 1.443 1992 0.801 0.072 0.125 0.408 -0.143 0.934 -0.082 -0.408 0.404 1993 0.594 0.370 0.089 0.456 -0.106 0.665 0.258 -0.090 0.798 1994 0.587 0.383 0.087 0.402 -0.092 0.647 0.286 -0.062 0.823 1995 0.688 0.223 0.076 0.255 -0.052 0.726 0.170 -0.160 0.667 1996 0.601 0.359 0.055 0.278 -0.039 0.626 0.319 -0.035 0.872 1997 0.537 0.471 0.068 0.330 -0.058 0.571 0.411 0.099 0.867 1998 0.400 0.766 0.066 0.371 -0.063 0.427 0.701 0.390 1.155 1999 0.329 0.961 0.081 0.294 -0.064 0.352 0.895 0.555 1.414 2000 0.376 0.827 0.069 0.436 -0.077 0.408 0.747 0.401 1.280 2001 0.240 1.278 0.075 0.368 -0.072 0.259 1.203 0.879 1.684 436 36th SAW Consensus Summary
Table D23. Survival (S) and fishing mortality (F) rates of striped bass >= 28 inches including estimates adjusted (adj.) for reporting rate (0.433), bias from live releases, and hooking mortality (0.08).
Coast Programs Massachusetts C-hat adjustment = 1.494; bootstrap GOF probability = 0.32 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1992 0.804 0.068 0.048 0.750 -0.087 0.880 -0.023 -0.118 0.083 1993 0.806 0.066 0.054 0.571 -0.076 0.872 -0.013 -0.104 0.086 1994 0.807 0.064 0.059 0.486 -0.072 0.869 -0.010 -0.103 0.093 1995 0.736 0.157 0.056 0.405 -0.057 0.781 0.098 0.026 0.175 1996 0.739 0.152 0.089 0.255 -0.062 0.788 0.088 0.018 0.164 1997 0.742 0.148 0.076 0.205 -0.042 0.775 0.105 0.036 0.179 1998 0.744 0.146 0.086 0.274 -0.064 0.795 0.079 0.010 0.154 1999 0.746 0.143 0.066 0.271 -0.047 0.783 0.095 0.026 0.169 2000 0.766 0.117 0.059 0.222 -0.034 0.793 0.082 0.011 0.158 2001 0.850 0.013 0.046 0.316 -0.036 0.882 -0.025 -0.101 0.059 New York - Ocean Haul Seine bootstrap GOF probability = 0.29 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1988 0.806 0.066 0.116 0.890 -0.230 1.050 -0.200 -0.310 0.006 1989 0.806 0.066 0.104 0.870 -0.200 1.011 -0.160 -0.272 0.044 1990 0.635 0.304 0.088 0.660 -0.130 0.734 0.160 0.092 0.235 1991 0.634 0.306 0.109 0.540 -0.140 0.742 0.150 0.087 0.217 1992 0.633 0.307 0.142 0.510 -0.190 0.780 0.100 0.039 0.163 1993 0.632 0.309 0.111 0.450 -0.130 0.724 0.170 0.111 0.242 1994 0.632 0.309 0.108 0.480 -0.130 0.725 0.170 0.104 0.249 1995 0.665 0.258 0.144 0.340 -0.140 0.769 0.110 0.028 0.214 1996 0.663 0.261 0.135 0.290 -0.110 0.743 0.150 0.069 0.240 1997 0.660 0.266 0.141 0.220 -0.090 0.725 0.170 0.095 0.261 1998 0.657 0.270 0.095 0.190 -0.050 0.690 0.220 0.139 0.319 1999 0.654 0.275 0.154 0.140 -0.070 0.701 0.200 0.113 0.317 2000 0.731 0.163 0.134 0.210 -0.080 0.795 0.080 -0.089 0.391 2001 0.740 0.151 0.092 0.210 -0.050 0.779 0.100 -0.064 0.410 36th SAW Consensus Summary 437
New Jersey - Delaware Bay bootstrap GOF probability = 0.48 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1989 0.819 0.050 0.104 0.565 -0.140 0.953 -0.100 -0.257 0.416 1990 0.817 0.052 0.135 0.833 -0.260 1.101 -0.250 -0.401 0.269 1991 0.578 0.398 0.249 0.500 -0.380 0.939 -0.090 -0.370 0.381 1992 0.616 0.335 0.080 0.710 -0.130 0.707 0.200 0.007 0.470 1993 0.646 0.287 0.100 0.417 -0.100 0.720 0.180 0.066 0.320 1994 0.686 0.227 0.103 0.466 -0.120 0.778 0.100 0.032 0.182 1995 0.715 0.185 0.102 0.448 -0.110 0.806 0.070 -0.038 0.204 1996 0.688 0.224 0.118 0.397 -0.120 0.782 0.100 0.004 0.210 1997 0.672 0.247 0.082 0.261 -0.050 0.709 0.190 0.123 0.276 1998 0.665 0.258 0.157 0.200 -0.090 0.734 0.160 0.085 0.244 1999 0.664 0.259 0.119 0.421 -0.130 0.761 0.120 0.015 0.261 2000 0.654 0.275 0.080 0.279 -0.050 0.692 0.220 0.061 0.441 2001 0.647 0.285 0.105 0.359 -0.100 0.716 0.180 -0.008 0.481 North Carolina - Cooperative Trawl Cruise C-hat adjustment = 1.545; bootstrap GOF probability = 0.092 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1988 0.709 0.194 0.105 0.750 -0.194 0.880 -0.022 -0.188 0.177 1989 0.701 0.205 0.059 0.720 -0.102 0.781 0.097 -0.062 0.286 1990 0.703 0.202 0.075 0.583 -0.110 0.791 0.085 0.008 0.168 1991 0.704 0.201 0.089 0.693 -0.153 0.831 0.035 -0.034 0.109 1992 0.714 0.187 0.106 0.531 -0.147 0.837 0.028 -0.044 0.105 1993 0.709 0.195 0.092 0.647 -0.150 0.834 0.032 -0.036 0.104 1994 0.703 0.203 0.077 0.628 -0.121 0.800 0.074 -0.008 0.162 1995 0.651 0.278 0.104 0.523 -0.143 0.760 0.125 0.019 0.243 1996 0.637 0.301 0.050 0.270 -0.035 0.660 0.265 0.180 0.358 1997 0.634 0.305 0.098 0.228 -0.063 0.677 0.240 0.149 0.341 1998 0.637 0.301 0.113 0.250 -0.082 0.694 0.216 0.118 0.324 1999 0.643 0.291 0.103 0.150 -0.045 0.674 0.245 0.118 0.390 2000 0.639 0.297 0.053 0.556 -0.072 0.689 0.223 0.078 0.392 2001 0.640 0.296 0.091 0.298 -0.074 0.692 0.218 0.069 0.394 438 36th SAW Consensus Summary
Producer Area Programs Delaware / Pennsylvania - Delaware River C-hat adjustment = 1.25; bootstrap GOF probability = 0.36 for the full parameterized model.
With trend models included:
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1993 0.870 -0.010 0.105 0.330 -0.090 0.960 -0.110 -0.270 0.090 1994 0.870 -0.010 0.085 0.290 -0.061 0.930 -0.070 -0.240 0.120 1995 0.590 0.380 0.120 0.350 -0.111 0.660 0.260 0.130 0.410 1996 0.580 0.390 0.152 0.280 -0.124 0.660 0.260 0.160 0.380 1997 0.570 0.410 0.080 0.520 -0.099 0.630 0.310 0.210 0.420 1998 0.560 0.430 0.150 0.170 -0.079 0.610 0.350 0.230 0.480 1999 0.550 0.450 0.093 0.210 -0.051 0.580 0.400 0.250 0.570 2000 0.545 0.460 0.160 0.170 -0.083 0.590 0.370 0.170 0.620 2001 0.540 0.470 0.120 0.120 -0.041 0.560 0.420 0.180 0.750 With trend models excluded:
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1993 0.860 0.000 0.105 0.330 -0.090 0.945 -0.090 -0.310 0.180 1994 0.860 0.000 0.085 0.290 -0.061 0.920 -0.060 -0.270 0.210 1995 0.575 0.400 0.120 0.350 -0.111 0.650 0.290 0.190 0.400 1996 0.575 0.400 0.152 0.280 -0.124 0.660 0.270 0.170 0.380 1997 0.575 0.400 0.080 0.520 -0.099 0.640 0.300 0.200 0.410 1998 0.570 0.410 0.150 0.170 -0.079 0.620 0.330 0.230 0.440 1999 0.570 0.410 0.093 0.210 -0.051 0.600 0.360 0.260 0.470 2000 0.580 0.390 0.160 0.170 -0.083 0.630 0.310 0.190 0.440 2001 0.580 0.390 0.120 0.120 -0.041 0.600 0.350 0.210 0.520 Maryland - Chesapeake Bay Spring Spawning Stock C-hat adjustment = 1.281; bootstrap GOF probability = 0.98 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1987 0.925 -0.072 0.034 0.000 0.000 0.925 -0.072 -0.136 0.225 1988 0.922 -0.069 0.041 0.670 -0.062 0.983 -0.133 -0.196 0.124 1989 0.919 -0.065 0.052 0.790 -0.091 1.011 -0.161 -0.224 0.068 1990 0.624 0.322 0.070 0.570 -0.092 0.687 0.226 0.062 0.451 1991 0.641 0.295 0.123 0.590 -0.178 0.779 0.100 -0.004 0.226 1992 0.658 0.268 0.113 0.510 -0.143 0.768 0.114 0.059 0.175 1993 0.675 0.244 0.099 0.460 -0.112 0.760 0.125 0.058 0.203 1994 0.689 0.222 0.093 0.460 -0.105 0.770 0.111 0.007 0.247 1995 0.644 0.289 0.115 0.260 -0.080 0.701 0.206 0.129 0.294 1996 0.643 0.292 0.097 0.280 -0.070 0.691 0.220 0.157 0.290 1997 0.640 0.296 0.112 0.220 -0.067 0.686 0.227 0.171 0.290 1998 0.637 0.300 0.099 0.190 -0.050 0.671 0.250 0.183 0.324 1999 0.635 0.304 0.120 0.180 -0.060 0.676 0.242 0.160 0.337 2000 0.731 0.163 0.083 0.190 -0.040 0.762 0.122 -0.042 0.419 2001 0.729 0.166 0.066 0.250 -0.040 0.760 0.125 -0.048 0.450 36th SAW Consensus Summary 439
Virginia - Rappahannock River C-hat adjustment = 1.860; bootstrap GOF probability = 0.12 for the full parameterized model.
Recovery % Live Bias Live 95%LCL 95%UCL Year S(unadj.) F(unadj.) Rate Release Release S(adj.) F(adj.) F(adj) F(adj) 1990 0.622 0.325 0.086 0.577 -0.127 0.712 0.189 0.094 0.294 1991 0.622 0.325 0.091 0.560 -0.131 0.716 0.184 0.090 0.287 1992 0.622 0.325 0.123 0.535 -0.176 0.755 0.131 0.038 0.233 1993 0.624 0.321 0.099 0.349 -0.094 0.689 0.222 0.126 0.329 1994 0.624 0.321 0.084 0.318 -0.072 0.672 0.247 0.148 0.356 1995 0.597 0.367 0.123 0.189 -0.070 0.642 0.294 0.179 0.423 1996 0.597 0.366 0.046 0.130 -0.015 0.606 0.351 0.237 0.479 1997 0.597 0.366 0.080 0.167 -0.037 0.620 0.329 0.216 0.456 1998 0.597 0.366 0.137 0.217 -0.093 0.658 0.269 0.155 0.397 1999 0.597 0.366 0.102 0.200 -0.059 0.634 0.305 0.190 0.436 2000 0.628 0.315 0.079 0.349 -0.073 0.677 0.239 0.081 0.428 2001 0.636 0.303 0.071 0.304 -0.056 0.674 0.245 0.075 0.448 440 36th SAW Consensus Summary
Table D24. QAICc weights used to derive model averaged parameter estimates given by Program MARK. Results are for Striped bass >= 18 inches.
Coast Programs Model MADFW NYOHS NJDEL NCCOOP
{S(t)r(t)} 0.0002 0.9808 0.9340 0.9999
{S(Tp)r(t)} 0.0089 0.0004 0.0649 0.0000
{S(p)r(t)} 0.0630 0.0000 0.0000 0.0000
{S(t)r(p)} 0.0385 0.0000 0.0000 0.0000
{S(.)r(t)} 0.1331 0.0000 0.0000 0.0000
{S(Tp)r(Tp)} 0.0663 0.0188 0.0011 0.0000
{S(Tp)r(p)} 0.0070 0.0000 0.0000 0.0000
{S(d)r(p)} 0.3254 0.0000 0.0000 0.0000
{S(v)r(p)} 0.3501 0.0000 0.0000 0.0000
{S(p)r(p)} 0.0047 0.0000 0.0000 0.0000
{S(.)r(p)} 0.0006 0.0000 0.0000 0.0000
{S(.)r(.)} 0.0024 0.0000 0.0000 0.0000 Producer Area Programs*
Model DE/PA
- DE/PA ** MDCB VARAP
{S(t)r(t)} 0.0200 0.0540 0.0033 0.9930
{S(Tp)r(t)} 0.4590 0.8023 0.0070
{S(p)r(t)} 0.1240 0.3299 0.1943 0.0000
{S(t)r(p)} 0.1240 0.0924 0.0001 0.0000
{S(.)r(t)} 0.1480 0.3947 0.0000 0.0000
{S(Tp)r(Tp)} 0.1600 0.0000 0.0000
{S(Tp)r(p)} 0.0090 0.0000 0.0000
{S(d)r(p)} 0.0100 0.0260 0.0000 0.0000
{S(v)r(p)} 0.0070 0.0300 0.0000 0.0000
{S(p)r(p)} 0.0150 0.0400 0.0000 0.0000
{S(.)r(p)} 0.0009 0.0280 0.0000 0.0000
{S(.)r(.)} 0.0100 0.0030 0.0000 0.0000
- DE/PA with trend models, ** DE/PA without trend models Model Descriptions S(.) r(.) Constant survival and reporting S(t) r(t) Time specific survival and reporting S(.) r(t) Constant survival and time specific reporting S(p) r(t) Regulatory period based survival and time specific reporting S(p) r(p) Regulatory period based survival and reporting S(.) r(p) Constant survival and regulatory period based reporting S(t) r(p) Time specific survival and regulatory period based reporting S(d) r(p) Regulatory period survival with terminal year unique and regulatory period reporting S(v) r(p) Regulatory period survival with 2 terminal years unique and regulatory period reporting S(Tp) r(Tp) Linear trend within regulatory period on both survival and reporting S(Tp) r(p) Linear trend within regulatory period survival and regulatory period reporting (no trend)
S(Tp) r(t) Linear trend within regulatory period survival and time specific reporting (no trend) 36th SAW Consensus Summary 441
Table D25. QAICc weights used to derive model averaged parameter estimates given by Program MARK.
Results are for striped bass tagged at >= 28 inches. Models are described in Table 5.
Coast Programs Model MADFW NYOHS NJDEL NCCOOP
{S(t)r(t)} 0.00002 0.00009 0.02076 0.03473
{S(Tp)r(t)} 0.00149 0.00022 0.24351 0.02508
{S(p)r(t)} 0.01026 0.00089 0.05423 0.05999
{S(t)r(p)} 0.00712 0.00090 0.01566 0.00193
{S(.)r(t)} 0.00997 0.00005 0.26631 0.05709
{S(Tp)r(Tp)} 0.03188 0.09525 0.25370 0.02335
{S(Tp)r(p)} 0.00443 0.02121 0.06528 0.07649
{S(d)r(p)} 0.70171 0.11307 0.00353 0.12263
{S(v)r(p)} 0.21241 0.64935 0.07345 0.22490
{S(p)r(p)} 0.01581 0.08943 0.00202 0.31851
{S(.)r(p)} 0.00197 0.01322 0.00054 0.04838
{S(.)r(.)} 0.00294 0.01632 0.00102 0.00690 Producer Area Programs Model DE/PA* DE/PA** MDCB VARAP
{S(t)r(t)} 0.00040 0.00080 0.00012 0.00000
{S(Tp)r(t)} 0.14500 0.23914 0.00008
{S(p)r(t)} 0.00390 0.00800 0.00213 0.00037
{S(t)r(p)} 0.00290 0.00600 0.00767 0.00019
{S(.)r(t)} 0.00030 0.00050 0.00000 0.00089
{S(Tp)r(Tp)} 0.00400 0.07671 0.00806
{S(Tp)r(p)} 0.36100 0.00020 0.02050
{S(d)r(p)} 0.09700 0.19800 0.00079 0.08558
{S(v)r(p)} 0.09900 0.20200 0.67319 0.24505
{S(p)r(p)} 0.26500 0.54100 0.00004 0.11910
{S(.)r(p)} 0.00600 0.01300 0.00000 0.17794
{S(.)r(.)} 0.01500 0.03100 0.00000 0.31845
- DE/PA with trend models, ** DE/PA without trend models 442 36th SAW Consensus Summary
Table D26. Total length frequencies of fish tagged in 2001 by program.
Coast Programs Producer Area Programs TL MADFW NYOHS NJDEL NCCOOP DE/PA MDCB VARAP 249 299 1 349 1 9 399 3 9 1 33 449 36 15 114 69 126 499 157 52 399 128 252 118 549 2 260 153 455 160 200 212 599 4 171 518 389 179 115 143 649 19 133 669 357 130 58 39 699 57 85 363 237 80 42 14 749 99 38 219 189 65 65 15 799 93 47 202 133 42 87 41 849 81 38 128 66 47 102 59 899 44 17 48 43 34 80 70 949 20 25 14 25 17 61 38 999 18 8 2 9 11 44 22 1049 10 5 2 2 13 27 14 1099 9 6 8 7
>1099 4 2 2 4 5 Total 456 1027 2385 2430 984 1314 797 Table D27. Age frequencies of tagged fish recaptured in 2001 by program.
Coast Programs Producer Area Programs AGE MADFW NYOHS NJDEL DE/PA MDCB VARAP 1
2 1 3 15 11 5 3 4 1 16 118 4 1 21 5 4 48 186 22 7 41 6 4 33 126 19 2 16 7 22 19 59 34 10 6 8 16 27 15 36 21 7 9 15 8 5 14 6 11 10 9 6 1 8 8 4 11 10 9 4 8 3 12 6 3 14 11 4 13 1 3 3 4 2 14 8 3 7 4 15 1 5 1 1 1 16 1 4 1 3 2 17 2 4 1 18 1 1 1 19 1 2 2 Total 101 206 521 166 95 124 36th SAW Consensus Summary 443
Table D28. Distribution of tag recaptures by state (program) and th Coast Programs Massachusetts (recaptures in 2001 from fish tagged and released during 1992-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 1 1 MA 5 11 11 5 2 34 RI 2 1 1 1 5 CT 1 1 1 3 NY 1 3 1 1 5 3 14 NJ 3 2 1 7 9 4 26 DE 1 1 2 MD 5 6 2 13 VA 3 1 1 4 2 11 NC 1 3 1 5 Total 0 4 1 9 12 7 15 12 6 13 24 11 114 New York - Ocean Haul Seine (recaptures in 2001 from fish tagged/release during 1988-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 3 6 5 14 NH 2 1 3 MA 7 14 6 5 5 3 40 RI 3 3 2 1 1 1 1 12 CT 2 1 1 2 4 2 1 13 NY 1 2 7 9 7 3 10 7 7 4 57 NJ 2 1 6 6 6 2 1 1 8 6 39 PA 0 DE 2 1 3 MD 1 1 1 1 1 5 VA 4 1 1 1 1 6 14 NC 0 Total 7 2 7 8 26 39 28 17 18 13 19 16 200 444 36th SAW Consensus Summary
New Jersey - Delaware Bay (recaptures in 2001 from fish tagged/release during 1989-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 1 2 9 3 1 16 NH 3 1 4 MA 12 23 30 19 16 6 106 RI 1 4 10 7 7 2 1 32 CT 1 4 4 4 3 1 1 18 NY 2 17 25 16 9 12 16 9 106 NJ 4 3 27 16 7 2 5 17 34 115 PA 1 1 2 4 DE 1 1 3 3 1 9 MD 2 3 1 1 2 1 3 2 15 VA 1 7 8 NC 1 1 Total 0 0 6 11 71 85 73 44 42 42 50 10 434 North Carolina - Cooperative Trawl Cruise (recaptures in 2001 from fish tagged/release during 1988-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 1 1 2 NH 0 MA 4 14 14 12 2 1 47 RI 1 5 1 7 CT 1 1 1 3 NY 4 4 3 3 6 3 23 NJ 1 2 2 1 3 9 18 PA 0 DE 1 1 1 1 1 1 6 MD 1 4 7 11 13 40 12 14 9 21 9 5 146 VA 2 9 6 1 8 2 2 1 1 16 35 21 104 NC 3 12 1 3 1 1 3 24 Total 6 26 15 17 34 69 33 33 19 45 54 29 380 36th SAW Consensus Summary 445
Producer Area Programs Delaware / Pennsylvania - Delaware River (1993 - 2001)
(recaptures during 1993-2001 from fish tagged/release during 1993-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 1 1 2 NH 1 1 MA 4 11 26 20 7 5 73 RI 1 7 4 5 4 1 22 CT 1 2 1 2 2 8 NY 4 6 9 5 3 6 2 1 36 NJ 3 10 62 63 27 29 23 55 50 8 330 PA 4 25 14 4 2 2 51 DE 1 9 13 16 37 33 17 7 10 10 6 159 MD 9 9 4 11 14 50 31 26 27 42 27 15 265 VA 5 3 5 1 4 1 1 3 28 22 73 NC 1 1 2 2 6 Total 16 13 25 59 117 186 132 105 76 124 119 54 1026 Maryland - Chesapeake Bay Spring Spawning Stock (recaptures in 2001 from fish tagged/release during 1987-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total ME 1 1 NH 1 1 MA 1 1 6 3 1 12 RI 2 2 1 1 1 7 CT 1 2 3 NY 2 1 2 4 1 2 12 NJ 4 2 3 9 PA 1 1 DE 1 1 MD 3 3 3 5 13 39 20 7 3 8 8 5 117 VA 1 1 4 5 4 10 6 31 NC 1 1 1 3 Total 4 4 5 5 21 53 31 17 6 17 23 12 198 Virginia - Rappahannock River (recaptures in 2001 from fish tagged/release during 1990-2001)
State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total MA 1 1 4 4 4 14 RI 2 1 2 5 CT 1 1 2 NY 1 1 3 5 NJ 2 4 1 7 MD 1 3 6 4 5 3 6 4 1 33 VA 1 6 23 7 3 2 1 7 15 8 73 NC 1 1 2 0
Total 1 2 6 23 14 13 9 13 13 17 20 10 141 446 36th SAW Consensus Summary
Table D29.Time series of survival (S) and total mortality (Z) estimates adjusted for live release bias.
Results are for age 1, 2, and older striped bass tagged during Western Long Island survey.
Reporting Rate (DE) = 0.433 Bootstrap GOF S(a*t) r(a*t) prob = 0.51; c-hat was estimated as model dev/mean simulation dev =
180.288/182.654 = 0.98, no c-hat adjustment was used.
Models and AICc weights used to derive model averaged parameter estimates given by Program MARK. All other models tested had delta AIC > 7, and AICc weight < 0.01.
Model AICc Weights S(a) r(a*v) 0.45 S(a) r(a*p) 0.40 S(a) r(a*d) 0.12 S(a) r(a*t) 0.02 Age 1 Survival Recovery % Live Bias Live LCLM (Z) UCLM (Z)
Year S(unadj.) Z(unadj.) Rate Release Release S(adj.) Z(adj.) Z(adj.) Z(adj.)
1988 0.277 1.29 0.02 1.00 -0.053 0.292 1.23 1.01 1.47 1989 0.277 1.29 0.01 1.00 -0.024 0.283 1.26 1.04 1.50 1990 0.277 1.29 0.06 0.87 -0.116 0.313 1.16 0.94 1.40 1991 0.277 1.29 0.03 0.91 -0.056 0.293 1.23 1.01 1.47 1992 0.277 1.29 0.01 0.80 -0.017 0.281 1.27 1.05 1.51 1993 0.277 1.29 0.03 0.88 -0.066 0.296 1.22 1.00 1.46 1994 0.277 1.29 0.02 0.86 -0.034 0.286 1.25 1.03 1.49 1995 0.277 1.29 0.01 0.75 -0.019 0.282 1.27 1.05 1.50 1996 0.277 1.29 0.01 0.77 -0.022 0.283 1.26 1.04 1.50 1997 0.277 1.29 0.07 1.00 -0.155 0.327 1.12 0.90 1.36 1998 0.277 1.29 0.02 1.00 -0.040 0.288 1.24 1.03 1.48 1999 0.277 1.29 0.01 1.00 -0.027 0.284 1.26 1.04 1.50 2000 0.277 1.29 0.02 0.94 -0.041 0.288 1.24 1.02 1.48 2001 0.277 1.29 0.00 0.81 -0.007 0.279 1.28 1.06 1.52 Age 2 Survival Recovery % Live Bias Live LCLM (Z) UCLM (Z)
Year S(unadj.) Z(unadj.) Rate Release Release S(adj.) Z(adj.) Z(adj.) Z(adj.)
1988 0.408 0.90 0.04 1.00 -0.097 0.452 0.79 0.62 1.00 1989 0.408 0.90 0.06 0.96 -0.128 0.468 0.76 0.58 0.96 1990 0.408 0.90 0.08 0.93 -0.155 0.483 0.73 0.55 0.93 1991 0.408 0.90 0.08 1.00 -0.170 0.492 0.71 0.53 0.91 1992 0.408 0.90 0.06 0.93 -0.124 0.466 0.76 0.59 0.97 1993 0.408 0.90 0.08 1.00 -0.163 0.487 0.72 0.54 0.92 1994 0.408 0.90 0.03 0.90 -0.056 0.432 0.84 0.66 1.04 1995 0.408 0.90 0.09 0.91 -0.172 0.493 0.71 0.53 0.91 1996 0.408 0.90 0.04 0.89 -0.076 0.442 0.82 0.64 1.02 1997 0.408 0.90 0.07 0.80 -0.120 0.464 0.77 0.59 0.97 1998 0.408 0.90 0.03 0.65 -0.048 0.429 0.85 0.67 1.05 1999 0.408 0.90 0.03 0.82 -0.045 0.427 0.85 0.67 1.05 2000 0.408 0.90 0.06 0.92 -0.119 0.463 0.77 0.59 0.97 2001 0.408 0.90 0.06 0.84 -0.109 0.458 0.78 0.60 0.98 36th SAW Consensus Summary 447
Table D29. Continued.
Age 3+ Survival Year S(unadj.) Z(unadj.) Recovery % Releasedbias S(adj.) Z(adj.) LCLM (Z) UCLM (Z) 1988 0.604 0.50 0.07 1.00 -0.161 0.719 0.33 0.26 0.40 1989 0.604 0.50 0.14 0.92 -0.289 0.849 0.16 0.10 0.24 1990 0.604 0.50 0.13 0.87 -0.265 0.822 0.20 0.13 0.27 1991 0.604 0.50 0.09 0.94 -0.177 0.734 0.31 0.24 0.38 1992 0.604 0.50 0.11 0.87 -0.222 0.776 0.25 0.19 0.33 1993 0.604 0.50 0.07 1.00 -0.153 0.713 0.34 0.27 0.41 1994 0.604 0.50 0.03 1.00 -0.070 0.649 0.43 0.37 0.51 1995 0.604 0.50 0.07 0.73 -0.121 0.687 0.38 0.31 0.45 1996 0.604 0.50 0.07 0.73 -0.116 0.683 0.38 0.32 0.46 1997 0.604 0.50 0.05 0.58 -0.066 0.647 0.44 0.37 0.51 1998 0.604 0.50 0.11 0.56 -0.147 0.707 0.35 0.28 0.42 1999 0.604 0.50 0.05 0.56 -0.057 0.641 0.45 0.38 0.52 2000 0.604 0.50 0.06 0.75 -0.101 0.671 0.40 0.33 0.47 2001 0.604 0.50 0.11 1.00 -0.230 0.784 0.24 0.18 0.32 448 36th SAW Consensus Summary
Table D30. Total length frequencies of WLI 2001 tag releases, and ages of WLI 2001 tag recaptures.
TL WLI AGE WLI 199 86 1 1 249 126 2 19 299 72 3 10 349 29 4 6 399 30 5 5 449 22 6 2 499 21 7 549 12 8 599 8 9 2 649 3 10 699 Total 45 749 799 1 849 899 949 999 1049 1099
>1099 Total 410 Table D31. Distribution of tag recaptures by state and month for all recaptures 1988 - 2001 State Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Total NB 1 1 2 ME 1 3 2 5 1 12 NH 0 MA 5 14 10 2 3 3 1 38 RI 3 5 2 1 3 3 1 18 CT 1 6 3 2 2 2 4 1 1 22 NY 5 3 8 34 54 67 63 63 85 119 73 16 590 NJ 1 1 1 3 1 3 1 3 11 3 28 PA 0 DE 1 1 MD 1 1 1 2 2 1 8 VA 1 1 1 1 4 NC 1 1 Total 7 4 12 39 76 89 78 77 96 135 87 24 724 36th SAW Consensus Summary 449
Table D32. R/M estimates of exploitation rates of >= 28 inch striped bass from tagging programs (with reporting rate adjustment of 0.43, and hooking mortality rate adjustment of 0.08).
Year NJDB NYOHS NCCOOP MA VA York VA Rap MDCB DE/PA NYHUD 1987
- 0.052 * *
- 0.031 0.006 *
- 1988
- 0.038 0.076 *
- 0.132 0.041
- 0.110 1989 0.019 0.060 0.048 *
- 0.007 0.037
- 0.083 1990 0.041 0.063 0.080 *
- 0.090 0.084
- 0.135 1991 0.333 0.131 0.076 0.051 0.107 0.125 0.135
- 0.102 1992 0.078 0.140 0.140 0.070 0.034 0.121 0.131 0.178 0.152 1993 0.089 0.135 0.112 0.041 0.090 0.163 0.123 0.213 0.172 1994 0.086 0.197 0.088 0.052 0.138 0.103 0.115 0.121 0.118 1995 0.122 0.144 0.142 0.089 0.229 0.298 0.208 0.142 0.153 1996 0.217 0.475 0.116 0.140 0.233 0.040 0.172 0.337 0.232 1997 0.255 0.133 0.202 0.098 0.643 0.192 0.239 0.323 0.335 1998 0.371 0.341 0.224 0.084 0.160 0.324 0.196 0.300 0.218 1999 0.173 0.258 0.236 0.137 0.005 0.232 0.198 0.177 0.225 2000 0.139 0.059 0.062 0.071
- 0.128 0.173 0.322 0.139 2001 0.154 ** 0.154 **
- 0.101 0.128 0.280 *
- Years when few or no striped bass were tagged and
- NYOHS and MA have fall tagging programs, and recapture interval of terminal year (2000) is fall 2000 to fall 2001; NCCOOP is a winter tagging program (Jan./Feb.) with recapture interval of terminal year (2001) from January 2001 to January 2002; others are spring tagging programs recapture interval of terminal year (2001) from spring 2001 to spring 2002.
Table D33. R/M estimates of catch rates of >= 28 inch striped bass from tagging programs.
(with reporting rate adjustment of 0.43)
Year NJDB NYOHS NCCOOP MA VA York VA Rap MDCB DE/PA NYHUD 1987
- 0.284 * *
- 0.388 0.080 *
- 1988
- 0.224 0.256 *
- 0.312 0.091
- 0.220 1989 0.233 0.215 0.141 *
- 0.090 0.095
- 0.285 1990 0.517 0.215 0.173 *
- 0.203 0.175
- 0.362 1991 0.620 0.345 0.206 0.156 0.155 0.212 0.277
- 0.250 1992 0.275 0.268 0.269 0.133 0.089 0.216 0.248 0.179 0.302 1993 0.230 0.273 0.278 0.106 0.211 0.266 0.266 0.326 0.348 1994 0.302 0.358 0.208 0.161 0.278 0.191 0.225 0.201 0.256 1995 0.240 0.267 0.275 0.187 0.310 0.336 0.274 0.252 0.250 1996 0.355 0.589 0.154 0.241 0.287 0.074 0.262 0.409 0.330 1997 0.445 0.133 0.254 0.203 0.930 0.228 0.298 0.345 0.437 1998 0.406 0.392 0.285 0.155 0.197 0.423 0.229 0.353 0.304 1999 0.322 0.258 0.273 0.151 0.068 0.273 0.237 0.197 0.315 2000 0.250 0.152 0.128 0.107
- 0.182 0.200 0.396 0.217 2001 0.230 ** 0.212 **
- 0.171 0.169 0.312 *
- Years when few or no striped bass were tagged and
- See footnote in Table D32.
450 36th SAW Consensus Summary
Table D34. R/M estimates of exploitation rates of >= 18 inch striped bass from tagging programs (with reporting rate adjustment of 0.43, and hooking mortality rate adjustment of 0.08).
Year NJDB NYOHS NCCOOP MA VA York VA Rap MDCB DE/PA NYHUD 1987
- 0.024 * *
- 0.051 0.021 *
- 1988
- 0.031 0.047 *
- 0.132 0.017
- 0.060 1989 0.037 0.035 0.032 *
- 0.046 0.013
- 0.059 1990 0.112 0.044 0.070 *
- 0.120 0.068
- 0.094 1991 0.055 0.053 0.085 0.051 0.114 0.075 0.102 0.031 0.077 1992 0.060 0.047 0.164 0.057 0.096 0.063 0.140 0.133 0.105 1993 0.030 0.046 0.106 0.038 0.101 0.114 0.111 0.116 0.123 1994 0.041 0.064 0.089 0.040 0.094 0.102 0.121 0.119 0.085 1995 0.061 0.035 0.139 0.064 0.169 0.196 0.196 0.129 0.132 1996 0.102 0.060 0.109 0.109 0.155 0.132 0.172 0.170 0.170 1997 0.111 0.032 0.166 0.103 0.223 0.200 0.210 0.156 0.250 1998 0.136 0.055 0.150 0.056 0.167 0.149 0.207 0.146 0.177 1999 0.057 0.044 0.219 0.090 0.118 0.153 0.163 0.117 0.152 2000 0.072 0.039 0.088 0.050
- 0.096 0.133 0.147 0.101 2001 0.093 ** 0.118 **
- 0.066 0.124 0.145 *
- Years when few or no striped bass were tagged and
- NYOHS and MA have fall tagging programs, and recapture interval of terminal year (2000) is fall 2000 to fall 2001; NCCOOP is a winter tagging program (Jan./Feb.) with recapture interval of terminal year (2001) from January 2001 to January 2002; others are spring tagging programs recapture interval of terminal year (2001) from spring 2001 to spring 2002.
Table D35. R/M estimates of catch rates of >= 18 inch striped bass from tagging programs.
(with reporting rate adjustment of 0.43)
Year NJDB NYOHS NCCOOP MA VA York VA Rap MDCB DE/PA NYHUD 1987
- 0.177 * *
- 0.080 0.157 *
- 1988
- 0.242 0.216 *
- 0.274 0.100
- 0.192 1989 0.297 0.193 0.119 *
- 0.205 0.082
- 0.232 1990 0.675 0.174 0.180 *
- 0.279 0.131
- 0.293 1991 0.234 0.202 0.200 0.156 0.252 0.157 0.187 0.100 0.272 1992 0.264 0.142 0.293 0.120 0.341 0.125 0.245 0.211 0.238 1993 0.189 0.187 0.207 0.124 0.235 0.214 0.187 0.253 0.285 1994 0.200 0.155 0.199 0.143 0.253 0.179 0.218 0.226 0.214 1995 0.211 0.139 0.232 0.183 0.294 0.255 0.290 0.263 0.223 1996 0.265 0.190 0.151 0.237 0.221 0.190 0.281 0.263 0.288 1997 0.332 0.141 0.227 0.199 0.305 0.239 0.306 0.261 0.356 1998 0.323 0.150 0.247 0.105 0.230 0.219 0.297 0.265 0.260 1999 0.190 0.152 0.274 0.107 0.160 0.216 0.232 0.192 0.233 2000 0.215 0.141 0.158 0.093
- 0.144 0.233 0.269 0.205 2001 0.217 ** 0.180 **
- 0.148 0.175 0.242 *
- Years when few or no striped bass were tagged and
- See footnote in Table D34.
36th SAW Consensus Summary 451
Figure D24. Comparison of VPA and Tag program fishing mortality estimates.
0.30 0.25 coastal tag F(adj) 0.20 0.15 0.10 0.05 0.00 0 0.05 0.1 0.15 0.2 0.25 0.3 VPA F Figure D25. Comparison of VPA and Cooperative Cruise Tag program fishing mortality estimates.
0.30 0.25 0.20 Tag F(adj) 0.15 0.10 0.05 0.00 0 0.05 0.1 0.15 0.2 0.25 0.3 VPA F 452 36th SAW Consensus Summary
Figure D26. Time series of VPA and Tag estimated fishing mortality.
0.35 0.3 0.25 VPA F Fishing Mortality Tag F(adj) 0.2 0.15 0.1 0.05 0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 Year 36th SAW Consensus Summary 453
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