Study

Hawaii longline tuna fishery temporal trends in standardized catch rates and length distributions and effects on pelagic and seamount ecosystems

  • Published source details Gilman E., Chaloupka M., Read A., Dalzell P., Holetschek J. & Curtice C. (2012) Hawaii longline tuna fishery temporal trends in standardized catch rates and length distributions and effects on pelagic and seamount ecosystems. Aquatic Conservation: Marine and Freshwater Ecosystems, 22, 446-488.

Actions

This study is summarised as evidence for the following.

Action Category

Use a different hook type

Action Link
Marine Fish Conservation
  1. Use a different hook type

    A replicated, controlled study in 1994–2010 in an area of pelagic water in the Pacific Ocean off Hawaii, USA (Gilman et al. 2012) found that using circle hooks in a longline tuna Thunnus spp. fishery did not typically reduce the amount of unwanted catch of other fish species compared to conventional J-shaped or tuna hooks. The data were reported as statistical results (response to hook design of standardized catch rates). Catch rates of unwanted shortbill spearfish Tetrapturus angustirostris and striped marlin Tetrapturus audax were lower on sets using the wider circle hooks than sets with the narrower J-style and tuna hooks, but catch rates of unwanted blue shark Prionace glauca and oceanic white tip shark Carcharhinus longimanus and bigeye thresher shark were higher. Swordfish Xiphias gladius and bigeye thresher shark Alopias superciliosus standardised catches were not affected by hook type. In addition, target catches of tuna species Thunnus obesus were higher on sets with circle hooks than J or tuna hooks. Observer data were analysed from the Hawaii longline tuna fishery, collected between March 1994–July 2010. Catch data from nearly 72 million hooks in 34,613 sets from 2,767 trips were included. The predominant hook types used were various designs and sizes of circle hook (6 main types), J hook (2 main types) and tuna hooks (4 main types) See original paper for hook specifications.

    (Summarised by: Chris Barrett/Natasha Taylor)

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