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Marine Ecology Progress Series

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MEPS 376:185-192 (2009)  -  DOI:

Distinguishing disease impacts from larval supply effects in a lobster fishery collapse

Richard A. Wahle1,*, Mark Gibson2, Michael Fogarty3

1Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine 04575, USA
2Rhode Island Division of Fish and Wildlife, Jamestown, Rhode Island 02835, USA
3Northeast Fisheries Science Center, National Marine Fisheries Service, Woods Hole, Massachusetts 02835, USA

ABSTRACT: We describe a time series analysis that differentiates the effects of variable larval supply and the mortality impact of shell disease on cohorts of the American lobster Homarus americanus in a southern New England, USA, coastal population. Prior to the onset of a shell disease epizootic in 1997, larval settlement alone fully explained 82% of the variation in the numbers of pre-recruit lobsters about to enter the Rhode Island lobster fishery. With the onset of shell disease, however, the model required an additional term for disease prevalence to provide a sufficient statistical fit to the observed data. Neither time trends in bottom temperature nor predatory fish provided significant additional explanatory power for variability in pre-recruit abundance. To our knowledge, this analysis constitutes the first demonstration in which cohorts of a benthic marine invertebrate have been successfully tracked from settlement to the threshold of a fishery by accounting for the joint effects of variable supply of new recruits and subsequent disease during post-settlement years. As such, it illustrates how factors altering the rate of post-settlement mortality over time can obscure predictive relationships between settlement and subsequent recruitment. A tight spawner-to-recruit linkage is therefore unlikely in coastal Rhode Island. The analysis underscores the value of maintaining parallel time series of different life stages, as well as the need to better quantify both pre- and post-settlement mechanisms that influence cohort success in marine populations.

KEY WORDS: Homarus americanus · Larval supply · Shell disease · Open population · Recruitment · Forecasting · Stock assessment

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Cite this article as: Wahle RA, Gibson M, Fogarty M (2009) Distinguishing disease impacts from larval supply effects in a lobster fishery collapse. Mar Ecol Prog Ser 376:185-192.

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