Can We Have All Species Simultaneously at B MSY ?

1. Can We Have All Species Simultaneously at BMSY ? or ‘Having your Fish and Eating Them Too’ William Overholtz Jason Link Chris Legault Robert Gamble Michael Fogarty Laurel Col

2. GARM Ecosystem Terms of Reference • Provide analyses to determine if the Northeast Shelf LME (Large Marine Ecosystem) can support the reference point biomasses (summed BRPs) required for the GARM species as well as the other demersal and pelagic fish resources in the region.

3. Motivation: Earlier Analyses Suggested System is Energy Limited ICNAF Two Tier System -Determine total system MSY: MS MSY 980,000 MT -Allocate catches for each species accounting for by- catch and making sure the total doesn’t exceed system MSY SS MSY 1,300,00 MT

4. Energy Constraints? Earlier Energy Budgets for Georges Bank indicated Production Is “Tightly Bound” with Most Fish Production Consumed by Other Fish (Cohen et al. 1982; Sissenwine et al. 1984)

5. NAFO Div. 5 and 6 Landings ICNAF Fish MSY Level

6. Approach: • Determine Combined BMSY and/or MSY Levels for all Fish Species based on Single Species Analyses • Compare with other Temperate Systems • Revisit Brown et al. (1976) • Develop Aggregate Surplus Production Models (ASPIC, ASP Models) • Energy Budget Models • Shelfwide Ecopath and EcoNetWrk Models Based on EMAX Analyses • Estimate Fishery Production Potential and Primary Production Required to Sustain Fisheries • Multispecies Production Model Simulations

7. Determine Combined BMSY and/or MSY Levels based on Single Species Analyses Empirical Summarize current information on the BRPs for GARM species and other fish components of the US Northeast Shelf LME. Express results on a unit area basis (t/km2) Compare to historic analyses, recent analyses, (mass balance models), current biomass, and biomass in other systems.

8. Aggregate BMSY and MSY Levelsfor Species Groups based on Single Species Analysis

9. Total Biomass and Density Estimates by Species Group

10. Develop Aggregate Surplus Production Models Assemble time-series of survey indices, landings, biomass. Use ASPIC and other multi-species surplus production models to estimate aggregate BRPs. Fit variations of SP=Bt-1-Bt+C Fit Schaefer and Pella-Tomlinson models (Mueter and Megrey 2007) Add environmental covariates Compare to summed single species results by group and total

11. GARM Species Relative Abundance (Spring)

12. GARM Species Relative Abundance (Autumn)

13. Energy Budget Calculations Pelagic Fisheries Demersal Fisheries Large Pelagics Coastal Sharks Sea birds Pelagic Sharks Baleen whales Odontocetes Pinnipeds Demersals Piscivores Medium Pelagics Demersals Omnivores Squid Demersal Benthivores Small Pelagics Anadromous Small Pelagics Commercial Larval & Juvenile Fish Small Pelagics Other Polychaetes Micronekton MegaBenthos Filterers MegaBenthos Other Meso- pelagics Shrimp MacroBenthos Other MacroBenthos Crustaceans Large Copepods Gelatinous Zooplankton MacroBenthos Molluscs Small Copepods Detritus- POC Bacteria Discards Primary Producers J. Link, B. Overholtz, C. Legault, L. Col, M. Fogarty

14. Energy Budget Approach • Using EMAX balanced budgets for 4 Combined regions (MAB, SNE, GB, GM) Areally weighted for B, P/B, C/B • Common diet with all nodes used from SNE • Summed for fisheries and bycatch • Used mass-balance eqns: Where C is consumption, P is production, R is respiration, and E is Excretion

15. Ecopath Formulation Where B is biomass, EE is Ecotrophic Efficiency, IM is Immigration, BA is Biomass Accumulation, P/B is the Production to Biomass Ratio, C/B is the Consumption to Biomass Ratio, DC is the Diet Composition, EM is emigration, and C is catch Indexed by species (I,j)

16. Estimate Fishery Production Potential and Primary Production Required to Sustain Fisheries FP = R {M} PP TE(TL-1) Where FP is Fishery Production Potential, R is a Retention Rate PP is Primary Production M is the fraction of PP Available to Higher Trophic levels, TE is Transfer Efficiency and TL is the Mean Trophic Level

17. Primary Production Primary Production based on Satellite-Derived Estimates

18. Trophic Position of Individual Species d15 N Trophic Level

19. Mean Trophic Level of Landings Relatively Constant

20. Results Sensitive to Transfer Efficiencies Transfer Efficiency 15% 12.5% 10%

21. MS & Aggregate Production Model Simulator

22. Model Details Programmed in Visual C# Uses 5th order Runge-Kutta iterative numerical solutions User friendly GUI developed Not an estimator or fitting tool Model description variously in print, in review, etc.

23. Model Parameterization • Set species, assign to guilds/groups • Determine system and guild carrying capacities, based on BMSY’s • System = 4.0 million mt • Groundfish = 1.42 million mt • Pelagics = 1.29 million mt • Elasmobranchs = 1.15 million mt

24. Single Species Dynamics No Interspecific Interactions

25. Individual Species with Interactions

26. Aggregate Species Dynamics

27. GARM Ecosystem TOR Status • Compilation of MSY and BMSY Estimates Complete • Preliminary Shelf-wide Network Model Available and Experimental Scenarios Initiated • Initial ASPIC Runs Completed for Aggregate Biomass • Preliminary Estimates of Fishery Production Potential and PPR Completed • Sensitivity Analysis of FPP and PPR underway for Transfer Efficiencies • Multispecies Production Model Simulator Implemented. • Preliminary Simulator Scenario Results Completed

28. Additional Material

29. Energy Budget Preliminary Results

30. Preliminary Energy Budget Conclusions • Rebalancing relative to input levels suggests may not be able to have all fish species at BMSY due to flow constraints • All scenarios were balanced largely predicated upon a higher small pelagic-commercial biomass and a lower demersal-omnivore and piscivore biomass

31. Preliminary Aggregate BRP Estimates