1. Developing a statistical-multispecies framework for a predator-prey system in the eastern Bering Sea: Jesús Jurado-Molina University of Washington Jim Ianelli, Patricia Livingston Alaska Fisheries Science Center

2. Ecological considerations in fisheries management Competition Predation Environmental Regime Shifts Habitat alteration

3. Scientific Framework to provide ecosystem-based advice in the Bering Sea Main goals for protecting ecosystem attributes: 1. Maintain predator/prey relationships 2. Maintain energy flow and balance 3. Maintain diversity Tools: 1. Multispecies models (biological interactions) 2. Multispecies models (technological interactions) 3. Full ecosystem models (ECOPATH, ECOSIM…)

4. Multispecies models (biological interactions) Deterministic models: 1. Multispecies virtual population analysis (MSVPA) 2. Multispecies forecasting model (MSFOR) Statistical models: 1. Multispecies statistical model (MSM)

5. Multispecies VPA

6. MSVPA-MSFOR models

7. Statistical catch-at-age models

8. Multispecies statistical model

9. MSM: assumptions Separable fishing mortality assumption (F a,t = s a F full,t ) M= M1+ M2 Constant annual predator ration Stomach content measured without error

10. Advantages of MSM: Multispecies approach Measuring indirect effects of fishing We can use the tools used in single-species stock assessments Likelihood profile Bayesian analysis (posterior distributions) Decision analysis Model selection (Akaike’s information criterion,likelihood ratio ) Able to make comparisons with the single-species stock assessment models in the same statistical framework

11. MSM (previous version) Included only two species (walleye pollock and Pacific cod) Set up in Excel Fitted only to catch at age data, total catch, bottom trawl survey and EIT survey Updated to 2002 data

12. MSM (new version) Three species, walleye pollock, Pacific cod and arrowtooth flounder Set up in AD model builder Fitted to total catch data, bottom trawl survey, pollock age composition, Pacific cod and arrowtooth length composition (from fishery), survey age and size composition, EIT survey (pollock) Updated to 2006 data

13. MSM system for the Bering Sea Walleye pollock Pacific cod Fishery Arrowtooth flounder

14. Walleye pollock N3+

15. Pacific cod N3+

16. Bottom trawl survey fit

17. Total catch fit

18. Average predation mortality at age

19. Pollock predation mortality

20. Walleye pollock predation mortality in 1979 (from MCMC with 3 million iterations)

21. Predation mortality comparison Slope = 0.9±0.02 r 2 = 0.92

22. Comparison of causes of death (numbers) - Pollock

23. Comparison of causes of death (biomass) - Pollock

24. Comparison of causes of death (spawning biomass) - Pollock

25. Walleye pollock Recruitment

26. Future tasks Addition of the complete set of stomach content data Module for model projections Module for technological interactions

27. Developing a statistical-multispecies framework for a predator-prey system in the eastern Bering Sea: Jesús Jurado-Molina University of Washington jjurado@u.washington.edu Jesus.Jurado-Molina@noaa.gov