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    By-catch analysis as a part of progress report for the research fishery of Dissostichus spp. in Subarea 48.6 by Japan and South Africa during 2012/13–2016/17

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    Numéro du document:
    WG-SAM-17/44
    Auteur(s):
    T. Okuda, S. Somhlaba and T. Ichii
    Soumis par:
    Takehiro Okuda (Japon)
    Approuvé par:
    Taro Ichii (Japon)
    Résumé

    This paper reports the preliminary results of by-catch analysis as a part of progress report for the research fishery of Dissostichus spp. in Subarea 48.6 by Japan and South Africa during 2012/13–2016/17. We have used data set provided by CCAMLR secretariat on 10th May, 2017.

    Although the by-catch occurred in most longline research operations, the number of by-catch individuals was less than 100 individuals in most of the operations. In most of longline operation, by-catch weight was less than 100 kg and less than 20 % of total catch. GRV and ANT are common by-catch species, which are caught at every research block and every year. ICX is also common by-catch species, but mainly fished at the ice ridge research blocks 48.6_4 and 48.6_5.

    The results of the GLM and its model selection with AIC criteria indicates that the number of by-catch GRV individuals is higher at southern research blocks (48.6_3, 48.6_4, and 48.6_5). On the other hands, the number of ANT by-catch individuals is highest at research blocks 48.6_1. As temporal change of by-catch, only GRV shows obvious decrease in number of by-catch individuals.