Journal Article

Distribution of population-based indicators across multiple taxa to assess the status of Gulf of Alaska and Bering Sea groundfish communities

Franz J. Mueter and Bernard A. Megrey

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 62, issue 3, pages 344-352
Published in print January 2005 | ISSN: 1054-3139
Published online January 2005 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2004.11.006
Distribution of population-based indicators across multiple taxa to assess the status of Gulf of Alaska and Bering Sea groundfish communities

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Ecosystem-based approaches to fisheries management require researchers and managers to take into account effects of fishing on other components of the ecosystem, including non-commercial species. Currently, stock assessments in the Northeast Pacific are limited to the most important commercial species, little being known about the status of non-commercial species. Nevertheless, standardized bottom-trawl surveys conducted in the eastern Bering Sea (EBS) and Gulf of Alaska (GoA), although primarily designed to assess commercial species, provide valuable information on the abundance, distribution, and mean weight of numerous taxa. Using a novel statistical approach and survey data for the years 1993–2003, we examined trends in catch per unit effort (cpue), frequency of occurrence, and mean weight of individuals for each taxon. Time trends were computed as the slope of a linear regression of each indicator on year, and were summarized separately for the eastern and western GoA and for the EBS. Within each system, trends were further compared between commercial and non-commercial taxa. Simulations were used to obtain reference distributions for the expected distribution of slopes across many dependent populations. Observed distributions of trends were compared with simulated distributions, suggesting that more taxa than expected showed a decreasing trend in cpue in the EBS, but not in the GoA. These trends likely resulted from low groundfish productivity in the EBS during the 1990s. At the same time, the frequency of occurrence of significantly more taxa than expected increased in the EBS and, to a lesser extent, in the western GoA. Increases in frequency of occurrence were much more common among non-commercial, invertebrate taxa, and may be a response to reductions in trawl fishing effort during the 1990s.

Keywords: Bering Sea; catch per unit effort; demersal community; frequency of occurrence; Gulf of Alaska; mean individual weight; randomization test; simulation envelope

Journal Article.  4956 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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