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Yellowfin Tuna 1975-2005

Yellowfin Tuna 1975-2005. Major Changes. Catch, effort, and length-frequency data for the surface fisheries have been updated to include new data for 2005 and revised data for 1975-2004.

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Yellowfin Tuna 1975-2005

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  1. Yellowfin Tuna 1975-2005

  2. Major Changes • Catch, effort, and length-frequency data for the surface fisheries have been updated to include new data for 2005 and revised data for 1975-2004. • Catch data for the Japanese longline fisheries have been updated for 2000-2003 and to include new data for 2004. • Catch data for the longline fisheries of Chinese Taipei have been updated for 2002 and new data added for 2003. • Catch data fore the longline fisheries of Korea have been updated to include new data for 2003 • Catch data for the longline fisheries of the Peoples Republic of China have been updated to include new data for 2003 and 2004. • Longline catch-at-length data for 2002-2003 have been updated and new data for 2004 added. • Longline catch per unit effort data have been standardized using a delta-lognormal model, updated to include 2004 data. • Growth model has been changed to fix length-at-age at the prior distribution of a Richards growth curve based on otolith data

  3. Sensitivity Analyses • Stock recruitment relationship • Asymptotic length

  4. Data • Fishery definitions • Catch • Effort • Length frequency

  5. Yellowfin Fishery Definitions

  6. Catch DIS south DIS central DIS coastal DIS north DOL south LL south LL north BB DOL coastal DOL north NA north NA south FO north FO south FO central FO coastal

  7. Effort DIS coastal DIS north DIS central DIS south LL south DOL south LL north BB NA north NA south DOL north DOL coastal FO coastal FO central FO south FO north

  8. CPUE DIS south DIS coastal DIS north DIS central LL south LL north DOL south BB NA north NA south DOL north DOL coastal FO coastal FO south FO north FO central

  9. Fixed Parameters • Natural Mortality • Fecundity at age • Sex ratio at age • Selectivity curves for the discard fisheries • The steepness of the stock recruitment relationship = 1 (no relationship)

  10. 0.5 0.4 0.3 Quarterly M -- M Trimestral 0.2 0.1 0.0 4 8 12 16 20 24 28 Age in quarters -- Edad en trimestres Natural Mortality

  11. 0.5 0.4 0.3 Percent female 0.2 0.1 0.0 0 5 10 15 20 25 Age in quarters Sex Ratio

  12. 6 5 4 Relative fecundity x maturity 3 2 1 0 0 5 10 15 20 25 Age in quarters Relative Fecundity

  13. Estimated parameters • Recruitment • Temporal anomalies, (no Seasonal component) • Catchability • Temporal anomalies • Selectivity • Initial population size and age-structure • Mean length at age • Variation of length at age

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

  15. Fit to the length-frequency LL south LL north BB DOL south NA north NA south DOL north DOL coastal FO south FO central FO coastal FO north

  16. Growth

  17. Fishing mortality

  18. Age Specific Fishing Mortality

  19. NA north NA south Selectivity DIS central DIS south DIS coastal DIS north LL north BB DOL south LL south DOL north DOL coastal FO north FO south FO coastal FO central

  20. Catchability LL north BB LL south DOL north DOL south DOL coastal NA north FO north NA south FO central FO south FO coastal

  21. Recruitment

  22. Recent length-frequency data (FO) 1 4 2 3 FO south FO central FO coastal FO north

  23. Recent length-frequency data (Unassociated) NA north NA south

  24. Recent length-frequency data (Dolphin associated) DOL north DOL south DOL coastal

  25. Recent length-frequency data (longline) LL north LL south

  26. Stock - recruitment

  27. Biomass

  28. Spawning Biomass

  29. Average weight Surface Longline LL south LL north NA south DOL north DOL coastal BB DOL south FO south FO central FO coastal FO north NA north

  30. No Fishing

  31. Fishery impact

  32. No Fishing and Fishery Impact

  33. Biomass Comparisons

  34. Reference points & projections • Assumptions • For MSY calculations • Average of 2002-2003 for fishing mortality • For forward projections • Average of 2002-2003 for catchability • 2004 effort

  35. SBR

  36. SBR

  37. AMSY by method

  38. AMSY with method removed

  39. AMSY with effort adjusted

  40. Yield

  41. AMSY quantities using F(y)

  42. Sensitivity: h = 0.75 • When the spawning population is 20% of its unexploited level the recruitment is 75% of its unexploited level • Biomass • Recruitment • SBR • Yield Curve • AMSY

  43. Biomass Comparison

  44. Recruitment

  45. Recruitment

  46. SBR

  47. Yield Curve

  48. Sensitivity to L∞:proportion YFT > given length

  49. Maximum length observed by yr

  50. Sensitivity to assumed L∞: Biomass

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