Analysis of accumulation performance of differing set net designs

In order to determine the accumulation performance of differing set-net des igns, catch analysis was conducted upon small scale set-nets of both the si ngle-trap and double-trap type. Total catch per haul was significantly high er after the design change to the double-trap net. The ratio of catch per i ntermittent haul to successive haul was defined as the accumulation index, which was used as an index to evaluate set-net accumulation performance. Th e accumulation index was calculated as 1.10 for the single-trap net and 1.5 2 for the double-trap net for the total catch. For the dominant species suc h as jack mackerel Trachurus japonicus, total catch increased after the des ign change, as did the accumulation index. In contrast, for species such as Japanese barracuda Sphyraena japonica, total catch decreased after the des ign change, as did the accumulation index. For any dominant species, the ca tch per haul and the accumulation index tended to increase or decrease in a similar manner. These results suggest that for each dominant species, catc h differences between set-nets of different designs can be attributed to ch anges in their accumulation performances.