屋外長水路での曳網模型による角目と菱目袋網の網目選択性の比較

概要

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For the regulation of fishery resources, an appropriate mesh size of traditional diamond mesh cod end is always chosen in the belief that undersized fish can escape from the cod end to grow to a suitable size for fishery later. However, because a diamond mesh cod end becomes too narrow at the middle, and the meshes are almost closed (with the exception of the end of the cod end) during trawling, the benefit of mesh regulation is insufficiently attained. To alleviate the problem, an improvement in selectivity was achieved by using square-mesh cod ends that have more open meshes. The experiments were conducted using cod ends with 4 mesh sizes (26, 31, 36 and 41mm) in a long waterway. The results for rainbow trout (Oncorhynchus mykiss) demonstrated that the square-mesh cod end, as compared with the diamond mesh cod end, could significantly reduce the catch of juveniles and obtain good selectivity.
日本水産學會の論文