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Environmental Effects on Recruitment of Northern Shrimp in the Gulf of Maine

Environmental Effects on Recruitment of Northern Shrimp in the Gulf of Maine. Anne Richards Michael Fogarty David Mountain NOAA National Marine Fisheries Service Woods Hole, MA. Outline. stock-recruit-environment relations mechanisms for recruit-env’t relation.

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Environmental Effects on Recruitment of Northern Shrimp in the Gulf of Maine

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  1. Environmental Effects on Recruitment of Northern Shrimp in the Gulf of Maine Anne Richards Michael Fogarty David Mountain NOAA National Marine Fisheries Service Woods Hole, MA

  2. Outline • stock-recruit-environment relations • mechanisms for recruit-env’t relation

  3. Northern ShrimpPandalus borealis • Boreal distribution • Gulf of Maine=southern limit • Locally important fishery from Shumway et al. 1985 Life history Fishery

  4. Impetus • Conventional wisdom: temperature = primary regulating factor • will “…not respond well to attempts to control exploitation” (Apollonio et al. 1986)

  5. Stock-Recruitment Series1968-2002

  6. Environmental Variables • Temperature anomalies (W Gulf of Maine) • fall bottom: developmental rates, egg parasitism • spring bottom: developmental rates, hatch timing • spring surface: larval development • NAO winter index

  7. Analysis • Box-Jenkins TSA to ID factors affecting recruitment • S-R with environmental inputs

  8. SSB 2 + Spring Surface TA - Spring Bottom TA 4 - NAO 1 - Results – TSASignificant crosscorrelations with recruitment Lag Sign 1 Planktonic larvae Male maturation, gender transition without 2002

  9. Stock-Recruitment Models

  10. Stock-Recruit-Temperature

  11. Conclusion • Shrimp recruitment dependent on SSB and spring temperatures (surface and bottom)

  12. Mechanisms: Spring SST • Spring surface temperature effect (larvae): • Appears intuitively correct • But counters laboratory studies: better growth and survival at warmer temperatures. • Indirect effect, e.g. match-mismatch?

  13. Match-Mismatch Hypothesis • Coastal Gulf of Maine: Bloom timing determined by solar insolation (Townsend and coauthors) • Shrimp development: temperature-dependent

  14. Match-Mismatch Hypothesis • Bloom timing • Hatch timing • Survival rates

  15. Bloom Timing • Townsend and Cammen (1988): 1971-1980 • CZCS and SeaWifs ’78-’86, ’98-’03

  16. Hatch Dates • Maine DMR fishery sampling, 1980-1983 and 1989-1993 • Probit analysis: 50% hatch, duration of hatch

  17. Hatch Timing

  18. Shrimp Development • temperature-dependent

  19. Bloom Onset and Hatch Timing

  20. Survival

  21. Larval Shrimp Diet • Zooplankton bloom ~ one month later (Townsend 1984) Stage I larvae Stickney and Perkins (1980)

  22. Implications

  23. Application • Management: Adjust fishing effort to allow higher egg deposition in warmer years

  24. Summary Stephen H. Clark 1) SSB and spring temperatures affect GoM shrimp rcrt 2) Spring SST effect may be mediated through match-mismatch

  25. Ongoing Work • Bloom timing • Solar insolation, 1982-1999 • CZCS / SeaWiFS, ‘83-’91, ‘97-’03 • Hatch timing

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