Environmental effects on recruitment of northern shrimp in the gulf of maine
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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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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


Northern ShrimpPandalus borealis

  • Boreal distribution

  • Gulf of Maine=southern limit

  • Locally important fishery

from Shumway et al. 1985

Life history

Fishery


Impetus

  • Conventional wisdom: temperature = primary regulating factor

  • will “…not respond well to attempts to control exploitation”

    (Apollonio et al. 1986)


Stock-Recruitment Series1968-2002


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


Analysis

  • Box-Jenkins TSA to ID factors affecting recruitment

  • S-R with environmental inputs


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


Stock-Recruitment Models


Stock-Recruit-Temperature


Conclusion

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


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?


Match-Mismatch Hypothesis

  • Coastal Gulf of Maine: Bloom timing determined by solar insolation (Townsend and coauthors)

  • Shrimp development: temperature-dependent


Match-Mismatch Hypothesis

  • Bloom timing

  • Hatch timing

  • Survival rates


Bloom Timing

  • Townsend and Cammen (1988): 1971-1980

  • CZCS and SeaWifs

    ’78-’86, ’98-’03


Hatch Dates

  • Maine DMR fishery sampling, 1980-1983 and 1989-1993

  • Probit analysis: 50% hatch, duration of hatch


Hatch Timing


Shrimp Development

  • temperature-dependent


Bloom Onset and Hatch Timing


Survival


Larval Shrimp Diet

  • Zooplankton bloom ~ one month later (Townsend 1984)

Stage I larvae

Stickney and Perkins (1980)


Implications


Application

  • Management:

    Adjust fishing effort to allow higher egg deposition in warmer years


Summary

Stephen H. Clark

1) SSB and spring temperatures affect GoM shrimp rcrt

2) Spring SST effect may be mediated through match-mismatch


Ongoing Work

  • Bloom timing

    • Solar insolation, 1982-1999

    • CZCS / SeaWiFS, ‘83-’91, ‘97-’03

  • Hatch timing


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