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  • 1
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    In:  http://aquaticcommons.org/id/eprint/15098 | 403 | 2014-05-28 03:33:32 | 15098 | United States National Marine Fisheries Service
    Publication Date: 2021-07-02
    Description: The relative abundance of Bristol Bay red king crab (Paralithodes camtschaticus) is estimated each year for stock assessment by using catch-per-swept-area data collected on the Alaska Fisheries Science Center’s annual eastern Bering Sea bottom trawl survey. To estimate survey trawl capture efficiency for red king crab, an experiment was conducted with an auxiliary net (fitted with its own heavy chain-link footrope) that was attached beneath thetrawl to capture crabs escaping under the survey trawl footrope. Capture probability was then estimated by fitting a model to the proportion of crabs captured and crab size data. For males, mean capture probability was 72% at 95 mm (carapace length), the size at which full vulnerability tothe survey trawl is assigned in the current management model; 84.1% at 135 mm, the legal size for the fishery;and 93% at 184 mm, the maximum size observed in this study. For females, mean capture probability was 70% at 90 mm, the size at which full vulnerability to the survey trawl isassigned in the current management model, and 77% at 162 mm,the maximum size observed in this study. The precision of our estimates for each sex decreased for juveniles under 60 mm and for the largest crab because of small sample sizes.In situ data collected from trawl-mounted video cameras were used to determine the importance of various factors associated with the capture of individual crabs. Capture probability was significantly higher when a crab was standing when struck by the footrope, rather than crouching, and higher when a crab was hit along its body axis, rather than from the side. Capture probability also increased as a function of increasing crab size butdecreased with increasing footrope distance from the bottom and when artificial light was provided for the video camera.
    Keywords: Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 740-749
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  • 2
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    National Oceanic and Atmospheric Administration, National Marine Fisheries Service | Silver Spring, MD
    In:  http://aquaticcommons.org/id/eprint/8954 | 403 | 2012-07-02 15:05:17 | 8954 | United States National Marine Fisheries Service
    Publication Date: 2021-06-29
    Description: EXECUTIVE SUMMARY: At present, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) criteria used to assess whether a population qualifies for inclusion in the CITES Appendices relate to (A) size of the population, (B) area of distribution of the population, and (C) declines in the size of the population. Numeric guidelines are provided as indicators of a small population (less than 5,000 individuals), a small subpopulation (less than 500 individuals), a restricted area of distribution for a population (less than 10,000 km2), a restricted area of distribution for a subpopula-tion (less than 500 km2), a high rate of decline (a decrease of 50% or more in total within 5 years or two generations whichever is longer or, for a small wild population, a decline of 20% or more in total within ten years or three generations whichever is longer), large fluctuations (population size or area of distribution varies widely, rapidly and frequently, with a variation greater than one order of magnitude), and a short-term fluctuation (one of two years or less).The Working Group discussed several broad issues of relevance to the CITES criteria and guidelines. These included the importance of the historical extent of decline versus the recent rate of decline; the utility and validity of incorporating relative population productivity into decline criteria; the utility of absolute numbers for defining small populations or small areas; the appropriateness of generation times as time frames for examining declines; the importance of the magnitude and frequency of fluctuations as factors affecting risk of extinction; and the overall utility of numeric thresh-olds or guidelines.
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 70
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