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Lingcod

Evaluating the sensitivity of biological reference points to variation in spatial and temporal selectivity. Hiroshi Okamura (NRIFS), Murdoch K. McAllister (UBC), Momoko Ichinokawa (NRIFS), Lynne Yamanaka (PBS), & Kendra Holt (PBS). Lingcod. Ophiodon elongates

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Lingcod

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  1. Evaluating the sensitivity of biological reference points to variation in spatial and temporal selectivity Hiroshi Okamura (NRIFS), Murdoch K. McAllister (UBC), MomokoIchinokawa (NRIFS), Lynne Yamanaka (PBS), & Kendra Holt (PBS)

  2. Lingcod • Ophiodonelongates • Important fish for commercial (trawl/hook & line) and recreational groundfish fishery off British Columbia • Most lingcod inhabit 10-100m depths • Fishing occurs in summer and winter We focus on trawl fishery. Lingcod from Wikipedia

  3. Map 3C

  4. Catch age at recruitment Trawl: 3 (1927~1994) 4 (1995~2003) 5 (2004~2012) Hook&Line: 3 Recreation: 2

  5. Growth

  6. Maturity ogive

  7. Seasonal and Vertical Movement SUMMER WINTER 100% 5% Mature Male 100% SHALLOW 50% 50% 95% Mature Female 50% 50% 95% DEEP 5% Immature fish

  8. Biological parameters Steepness h = 0.7 B0 = 50,000 (tons) M = 0.193 (year-1)

  9. Semi-Age Structured Delay-Difference Model • Recruitment ≠ Maturity • Can handle multiple fisheries with different age at recruitment • Can deal with difference in sex • Can take maturity curve into account

  10. SASDDM g = 0: male, = 1: female Age Structured Model Ordinary DDM

  11. SASDDM kmin ≤ a≤ kmax– 1

  12. SASDDM a ≥kmax

  13. Survival & Catch Equations s = 0: summer, = 1: winter d = 0: shallow (< 50m) , = 1: deep (> 50m) m = 0: immature, = 1: mature , where movement matrix componentby depth, season, and sex× maturity proportion by age and sex }, , , summer i: fishery winter

  14. Reproduction : maturation rate by age

  15. MSY estimation wS SUMMER WINTER 1.0 0.0 • Fix F for Hook&Line and Recreation • F for Trawl is only the control parameter • FMSY = argmax Catch(F) FS,D = wS×wD×F wS = proportion of efforts allocated for summer = 0.0, 0.1, …, 1.0 wD= proportion of efforts allocated for shallow = 0.0, 0.1, …, 1.0 100% 1.0 5% 100% SHALLOW 50% wD 50% 95% 0.0 50% 50% 95% DEEP 5%

  16. Movement matrix Proportion of fish inhabiting the deep water (> 50m) MATRIX 0 MATRIX 1

  17. MSY (tons) Shallow MATRIX 0 MATRIX 1 Summer Winter Winter Summer Deep

  18. BMSYL (=BMSY/B0) Shallow MATRIX 0 MATRIX 1 Summer Winter Winter Summer Deep

  19. %SPR Shallow MATRIX 0 MATRIX 1 Summer Winter Winter Summer Deep

  20. SY Matrix 1 Summer/Deep Winter/Shallow Total Male Female

  21. MSY for current fishing pattern • 2012 lingcod trawl catch in 3C (ton) • wS = 0.9 (summer), wD= 0 (deep): MSY = 1578.48 ton

  22. MSY estimation based on surplus production models • Estimate r and K using time series data of biomass and catch • Surplus production St = Bt+1 – Bt + Ct • argminr, K {St – E(St)}2 Fox Model E(St) = rBt{1-log(Bt)/log(K)} MSY = rK/{log(K)e} FMSY = r/log(K) BMSY = K/e Schaefer Model E(St) = rBt(1-Bt/K) MSY = rK/4 FMSY = r/2 BMSY = K/2

  23. MSY based on SPM Fox Model Schaefer Model MSY = 1468.4 (ton) MSY = 1895.2 (ton)

  24. Summary and Conclusions • SASDDM could be useful for evaluating seasonal & spatial effort controls for B.C. lingcod • MSY and BMSY change nonlinearly as effort allocation changes – due to differences in habitat by sex • %SPR covers broad range by different effort allocation • MSY based on SPM may be biased – future simulation study • Future work: CPUE standardization by season and depth, estimation of steepness and initial biomass, state-space modelling, and future projection

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