Multispecies Virtual Population Analysis Summary of Model, Applications, and Advances

1. Multispecies Virtual Population Analysis Summary of Model, Applications, and Advances Lance Garrison, Jim Ianelli, Megan Tyrrell, Jason Link NEMoW Workshop 28-31 August 2007

2. Structure of MSVPA Model Suitability Params. Diet Data Consumption = Predator BM * %DR Other Food Pprey = (Suitable Biomass)prey / Total Suitable Biomass M2age Cprey = Consumption * Pprey M2prey = Cprey / BMprey BMage BMage BMage BMage BMage Other Predators Single Species VPA

3. Applications of MSVPA Implementation in the “4M” Package from ICES North Sea – ICES Working Group Cod, Haddock, Whiting, Pout, Saithe, Herring, Sprat, Mackerel, Plaice, Sand lance Northeast US – Tsou & Collie Cod, Haddock, Dogfish, Hakes, Herring, Mackerel, Sand Lance, Skates, Flounder Eastern Berring Sea – Livingston & Juardo-Molina Walleye Pollock, Pacific Cod, Turbot, Yellowfin Sole, Arrowtooth Flounder, Fur Seal, Rock Sole, Pacific Herring

4. A slice of the food web

5. Model Inputs and Data Requirements Age-structured catch and biological information for all predator and prey species and associated tuning indices for VPAs Diet data including prey size/age information Consumption parameters: daily rations or temperature dependent evacuation rates Other food biomasses (and/or other predators)

6. Known Weaknesses in MSVPA Overparameterized - not a statistical model that fits data and provides uncertainty 4M formulation results in a Type II feeding response which leads to depensatory dynamics at low pop. Sizes Assumes constant suitability parameters and requires a comprehensive, large scale diet data set Data intensive – but then so are all Ecosystem Models

7. Expanded MSVPA (MSVPA-X) Developed for ASMFC to address interactions between Atlantic Menhaden and its major predators Explicitly incorporates tuned VPAs in the form of extended survivors analysis Implements a “weak” Type III feeding response Decomposes “suitability” into preference, spatial overlap, and size preference - increases the ability to assimilate data - results in dynamic suitabilities Implements a predator growth model

8. NEUS Application of MSVPA-X Megan Tyrrell, Jason Link

9. NEUS Application of MSVPA-X Five most important predators Spiny Dogfish, Winter Skate, White Hake, Northern Goosefish, Georges Bank and South Cod Megan Tyrrell, Jason Link

10. NEUS Application of MSVPA-X Megan Tyrrell, Jason Link

11. Multispecies statistical model Jim Ianelli

12. MSM Implementation: Eastern Bering Sea • Species: • Pollock, Pacific cod and arrowtooth flounder • Coded in C++ (ADMB) • Tuned to: • Fishery catch • Survey indices • Age (pollock) and length (arrowtooth flounder, Pacific cod) compositions Jim Ianelli

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

14. Pollock abundance (age 3+)

15. Pollock recruitment

16. Why Use MSVPA or MSM Approaches ? These are MRM models, so suited for specific questions or trophic interactions Data rich situations with age-structured catch and biological data for a few species Both data and outputs are directly related to SS assessment models. As such, easy to compare to data and a common “language” for managers Poised for “tactical” advice