標識放流結果から推定された本邦太平洋沿岸ブリ資源の回遊モデルと動態-I : 放流年再捕結果からの推定

概要

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A migration system model was constructed on the basis of information obtained from the tagging experiments. Two migration routes start from Sagami Bay and Kumano-nada area, central Japan. One is southward migration in spring in the direction of Kyushu, and the other is northward migration in summer to northern Japan. Recapture data within the year of release were applied to this system model and the fishing rate, transfer rate, and the rate of disappearance were estimated. In 1926-1938 period, about 80% of southward migrants disappeared from both Kumano-nada and Tosa Bay and discontinuity of the distribution of the population at these points was suggested. In 1963-1965 period the boundary at Kumano-nada disappeared and 85% of fish moved south from there toward Tosa Bay. More than a half of the fish which once disappeared from Sagami Bay and Kumano-nada in the spring season reappeared in northern Japan in summer. The fishing rate for southward migrants in the spring season was about 20% in 1926-1938 period, but in 1963-1965 the rate increased to more than 30% in Sagami Bay and Kumano-nada. The fishing rate was low in northern Japan being not more than 10% in both periods.
日本水産學會の論文