ASSESSMENT OF BIGEYE TUNA ( THUNNUS OBESUS ) IN THE EASTERN PACIFIC OCEAN

1. ASSESSMENT OF BIGEYE TUNA (THUNNUS OBESUS) IN THE EASTERN PACIFIC OCEAN January 1975 – December 2005

2. Overview of assessment • Age-structured, statistical, catch-at-length model (A-SCALA). • Quarterly time step from 1975 to the start of 2005. • No net movement of fish between the eastern and western Pacific.

3. Major changes • No major model changes except new and updated catch, effort, and length-frequency data.

4. Sensitivity analyses • Spawner-recruitment relationship (steepness = 0.75) • Assumed value for the asymptotic length parameter of the Richards growth curve • Inclusion of the Chinese Taipei longline length-frequcy data • Relationship between recruitment an the el Nino index

5. 8 5, 13 9 3, 11 4, 12 1, 6-7 2, 10 Bigeye fishery definitions Recent FLT (2-5) Discards (10-13) N Longline (8) S Longline (9) Early FLT (1) Early & Recent UNA (6, 7)

6. S LL N Offshore FLT Early UNA Recent UNA N LL Early FLT S Offshore FLT Equatorial FLT Coastal FLT Catch

7. Effort S LL Recent UNA N LL N Offshore FLT Early UNA Equatorial FLT Coastal FLT Early FLT S Offshore FLT

8. S LL N Offshore FLT Early UNA Recent UNA N LL Early FLT S Offshore FLT Equatorial FLT Coastal FLT CPUE

9. Recent UNA N LL S LL Coastal FLT N Offshore FLT Early UNA Early FLT S Offshore FLT Equatorial FLT Length frequency data

10. Discards Northern FLT Inshore FLT Southern FLT Equatorial FLT

11. Results • Fit to the length frequency • Growth • Fishing mortality • Selectivity • Recruitment • Biomass • Catchability

12. Recent UNA N LL S LL Coastal FLT N Offshore FLT Early UNA Early FLT S Offshore FLT Equatorial FLT Average fit to the length frequency data

13. Fit to recent length frequency data

14. Fit to recent length frequency data

15. Growth

16. Fishing mortality 1-4 5-8 13-16 9-12 21-24 17-20 29-32 25-28 37-40 33-36

17. Age-specific fishing mortality

18. Selectivity Recent UNA N LL Early UNA S LL Coastal FLT N Offshore FLT Early FLT S Offshore FLT Equatorial FLT

19. Catchability N Offshore FLT Equatorial FLT Coastal FLT Early FLT S Offshore FLT

20. S LL N LL Recent UNA Early UNA Catchability

21. Northern FLT Inshore FLT Equatorial FLT Southern FLT Catchability

22. Recruitment

23. Biomass

24. Spawning biomass

25. No-fishing plot

26. Average weight Combined Surface Combined LL Early UNA Recent UNA N LL S LL Early FLT Coastal FLT N Offshore FLT Galapagos FLT S Offshore FLT

27. Biomass

28. Recruitment

29. Comparisons to reference points • Spawning biomass depletion • Yield curve

30. Spawning biomass ratio

31. SBR comparison with last year

32. Time varying indicators

33. Yield curve

34. AMSY-quantities

35. AMSY-quantities -- assumed F

36. AMSY-quantities – by fishery

37. Forward simulations • Spawning biomass depletion • Biomass • Surface fishery catch • Longline catch

38. Spawning biomass ratio

39. Biomass

40. Predicted catches

41. Stock-recruitment relationship (h = 0.75)

42. Biomass

43. Recruitment

44. Spawning biomass ratio

45. Spawner-recruitment curve

46. Yield curve

47. Assumed value for the asymptotic length parameter of the Richards growth curve

48. Growth curves

49. Maximum length

50. Likelihoods