Re-Estimation of Biological Reference Points for New England
Re-Estimation of Biological Reference Points for New England Groundfish Stocks Terms of Reference Working Group Composition and Support Background to Re-Estimation Project Description of Working Group Procedures & Report Summary of Specific Results and Terms of Reference assemble appropriate abundance, catch and other data for 19 stocks included in the Northeast Multispecies FMP agree on appropriate methodology with which to estimate maximum long-term yield and associated biomass and fishing mortality rates revise estimates of Bmsy and F msy (or proxies) as appropriate project stock status through 2009 relative to long-term biomass targets and calculate maximum fishing mortality rates necessary to achieve targets (if possible) comment on methods to estimate target mortality rates for rebuilt stocks that minimize probability stocks will fall below Bmsy in the future Working Group Composition Outside Members: Dr. Jim Armstrong NCDMF Mr. Stratis Gavaris DGO-NB Dr. Pamela Mace NMFS-O/S&T Dr. Rick Methot NMFS-NWFSC Dr. Grant Thompson NMFS-AKFSC Dr. Doug Vaughan NMFS-SEFSC Council Observers: Mr. Tom Nies Mr. Steve Correia (MDMF) NEFSC Participants:
Dr. Jon Brodziak Mr. Steve Cadrin Dr. Chris Legault Mr. Ralph Mayo Dr. Steve Murawski - Chair Ms. Loretta OBrien Dr. Bill Overholtz Dr. Paul Rago Dr. Fred Serchuk Dr. Mike Sissenwine Dr. Mark Terceiro Ms. Susan Wigley Experts in Reference Point Estimation Experienced with NMFS SFA Guidelines (authors) Expedited Process Background New data available, especially documenting re-building of many stocks (important in determining conditions for re-building) Some reference points inconsistently determined with assessment methods and data (e.g., some results from Overfishing Panel) Surplus Production Models tend to Find Bmsy and Fmsy within the Range of observed data (even for chronically overfished stocks) (scallop example, haddock example) Recommendations for multiple approaches applied to data sets (NRC Reviews) Proxy reference points (survey biomass and exploitation indices) currently not linked to re-building schedules Biomass Reference Point OFD Committee : Average Recruitment * Biomass/recruit Georges Bank Haddock Landings (Metric Tons ('000s))
1940 1950 1960 1970 Year Class 1980 1990 2000 Georges Bank Haddock Spawning Stock Biomass (k mt) 200 175 150 125 100 75 50 25 0 1930 1940 1950 1960 1970 Year Class 1980 1990 2000 Groundfish Trawl Mesh 1952 (by H. Graham)
GEORGES BANK GROUNDFISH TRAWL SEA SAMPLING - 1913 HADDOCK HAKE COD REDFISH DISCARD LANDED SILVER HAKE DOGFISH FLOUNDERS SKATES G. SOLE ANGLER OTHERS 0 10 20 30 40 50 Percent of Catch Sampled 60 70 Procedures and Report 4 Primary Methods Used to Estimate Bmsy & Fmsy -Parametric Stock-Recruitment Models - Non-Parametric Empirical Approach - Surplus Production Models (ASPIC) - Index-Based Methods Up to 24 different parametric functional forms fit to S-R Data - selection criteria developed - Curved relationships considered but not without mechanism - Compared with non-parametric approach Non-parametric approach applied BPR * some statistical moment of
the recruitment distribution (mean, median, quartiles) Surplus production estimates from SARC 33 Reviewed for GB Winter Flounder & White Hake Accepted New Index Methods developed and tested (Replacement Ratio) What do we mean by Functional Forms? Georges Bank Yellowtail Flounder 80 70 60 50 40 30 20 10 0 0 20 40 60 BH ABH PBH PABH PRBH PRABH P2BH P2ABH PRHCBH PRHCABH RK ARK PRK PARK VPA Data F=0 F(0.1) F40% Fmsy FMAX Georges Bank Yellowtail Flounder Recruitment (age 1, millions)
1.5 6 1.0 5 0.5 4 3 2 1 0 60 70 80 90 Year 100 110 60 70 80 90 Year 100 110 Relative F Landings (mt) 0.10 110 Fall Survey (kg/tow) Fall Survey (kg/tow)
Replacement Ratio 6-panel Plots 0. 5 Gulf of Maine Haddock 60 7 50 6 Biomass Index (kg/tow) Landings (metric tons, '000s) 8 5 4 3 2 1 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 Year MSY/ Biomass Index = relF Fall Index Spring Index 40 30 20 10 0 1960 1965
1970 1975 1980 1985 1990 1995 Year 5.1/X = 0.23, applying algebra, Target Biomass Index = 22.17 2000 Gulf of Maine and Georges Bank Haddock Closely Linked Fall Surveys Gulf of Maine Haddock (kg/tow) 100 10 1 0.1 0.01 0.1 1 10 100 Georges Bank Haddock (kg/tow) 1000 GM Cod Fs 2000 MSY, rebuild
GB Cod GB Haddock GB Yellowtail SNE Yellowtail CC Yellowtail F-2000 F-msy F-rebuild Plaice Witch SNE Winter Fl. GB Winter Fl. Redfish White hake 0.00 0.25 0.50 0.75 Fishing Mortality Rate (F) 1.00 GM Haddock MA Yellowtail Pollock N. Window F-2000 F-msy S. Window Ocean Pout 0 1 2
3 4 5 6 Fishing Mortality Rate Index (refF) 7 GM Cod GB Cod GB Haddock GM Haddock GB Yellowtail 2001 Catches vs. MSYs SNE Yellowtail CC Yellowtail MA Yellowtail Plaice Sum 2001 = 69.2 Sum MSY = 192.9 (36%) 2001 Catch MSY Witch SNE Winter Fl GB Winter Fl Redfish White Hake Pollock N. Window S. Window Ocean Pout Halibut 0 10 20
30 40 Catch ('000s metric tons) 50 60 Gulf of Maine -Fall Survey Indices (kg/tow) Each Stock Plotted Vs. sum of all others Fall Index (kg/tow) Jackknife Plots 25 20 15 64 68 71 79 80 6566 77 67 75 73 81 GOM Cod 70 72 10 74 8483 85 69 78 00 10.00
5 63 GOM Haddock 63 75 76 95 93 88 91 98 90 89 87 92 20 40 60 80 100 Total Index w/o Witch Flounder Ratio of Biomass in 2000 to Re-Estimated Bmsy Pout S. Window N. Window Pollock White Hake Redfish GB Winter Fl SNE Winter Fl Witch Plaice MA YTF CC YTF SNE YTF GB YTF GM Haddock GB Haddock GB Cod GM Cod 0.00 0.25
0.50 0.75 1.00 B-2000 / B-msy Figure 4.3.3. Ratio of biomass in 2000 to Bmsy for 18 groundfish stocks. Specific Results & Advice Biomass and Fishing mortality reference points have been updated for 15 of the 19 stocks considered For only two stocks the surplus production estimates of Bmsy and Fmsy are retained (GB Winter Flounder, White Hake) For all stocks, reference point estimation is now compatible with stock monitoring methods No indication that Multispecies interactions will limit attainment of revised biomass targets Projections in the medium term are problematic for a few stocks Working Group recommends an Adaptive Approach to Biomass
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