Jesús Jurado-Molina School of Fisheries, University of Washington Patricia Livingston

1. Multispecies perspectives on the Bering Sea Ground Fishery Management Regime Jesús Jurado-Molina School of Fisheries, University of Washington Patricia Livingston Alaska Fisheries Science Center-NMFS

2. Changes in the Bering Sea

3. Levels of fishing mortality used in MSFOR AND SSFOR PLK - walleye pollock, COD - Pacific cod, GTB - Greenland turbot, YFS - yellowfin sole, SOL - rock sole, HER - Pacific herring

4. Objective • To apply the single and multispecies forecasting models to assess the long-term effects produced by three harvesting regimes (Fref,FABCand F = 0) on yield, total and spawning biomass of some species from the Bering Sea.

5. Biomass flow in the system defined for the eastern Bering Sea

6. MSVPA and MSFOR equations BS - suitable prey biomass S - suitability coefficient of predator i and prey p R - annual consumption of the predator i W - weight at age of prey p M1- residual mortality M2 - predation mortality

7. Multispecies forecasting assumptions • M = M1 + M2 • Constant annual consumption of predators. • Other food = constant • Constant suitability coefficients (from MSVPA) • Constant recruitment • Recruitment of age-0 individuals takes place in the third quarter

8. Input and output data for the MSFOR model

9. Methods • MSVPA run updated to 1998 data to obtain average suitabilities, average recruitment values and population initial values (1998) for all species. • Three MSFOR runs (Fref, FABC and F = 0) to obtain three equilibrium indicators: yield, total and spawning biomass • Three Single species runs using the same fishing mortalities and obtaining the same indicators • Comparison of the relative change of the indicators using:

10. Results: total population

11. Results: yield

12. Long-term percentage changes of yield MSP- Multispecies forecast, SSP - single species forecast

13. Long-term percentage changes of total and spawning biomass (Fref vs FABC) Proportion of Pacific herring population consumed by predators Proportion of pollock total population consumed by predators Biomass - total biomass SSB - spawning biomass

14. Long-term percentage changes of total and spawning biomass (Fref vs F = 0) Proportion of rock sole population consumed by predators Proportion of pollock population consumed by predators Biomass - total biomass SSB - spawning biomass

15. Conclusions • SSFOR and MSFOR suggest that the implementation of FABC would produce small long-term changes in the structure of the eastern Bering Sea groundfish populations compared to Fref. • Changes in the F regime can indirectly affect the predation mortality of prey due to decreases in predator population and consumption of prey. • The implementation of the FABC regime resulted in no significant change in pollock predation mortality due to canceling effects of pollock consumption by arrowtooth flounder and adult pollock (cannibalism) • When FABC was implemented, SSFOR and MSFOR predicted almost the same trends for the indicators analyzed. However, some differences in magnitude and direction due to predation interactions were observed for rock sole and Pacific herring. • Multispecies simulations of no fishing scenarios change our perspective on recovery times for depleted populations.

16. Future tasks • To simulate the system with different levels of recruitment associated to climate shifts • To carry out Monte Carlo simulations for MSFOR and SSFOR incorporating different assumptions on recruitment (Ricker/B&H and stochastic components) • To include the predation equations in a system of linked catch at age models (Multispecies CAGEAN?)