魚類の日周行動と定置網

概要

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The investigation of the behaviour of flying fishes, Cypselurus heterurus doderleini, and Cypselurus opisthopus hiraii Abe, with the scanning sonar was conducted day and night in the set-net fishing ground of Goto Islands in October 1983. The results are that the fish schools mainly have diurnal migration activity. They migrated offshore from early in the morning till noon and they moved inshore from afternoon till evening. The size of fish schools was larger early in the morning than in the day time. They mainly swim near the surface and have many variations of schooling. When the schools were moving offshore eazly in the morning, they were caught by the set-net. The fish schools were held and led to the mouth of the set-net by the leader net. Only those fish schools that moved to the mouth of the set-net were caught, due to the fact that many fish schools have an avoiding reaction toward the body of the net.