日本海ズワイガニ漁業における "水ガニ" 漁獲禁止の有効性 Effectiveness of Prohibition of Taking Soft-shell Male Snow Crab Chionoecetes opilio in the Sea of Japan
The present paper investigates the carapace width compositions of soft-shell males <i>Chionoecetes opilio</i> caught by Danish seiners and the effectiveness of prohibition of catching soft-shell males in order to keep the optimum sex ratio at 0.47 (ratio of the number of terminal molt males with hard-shell to the number of multiparous females). The sex ratio was estimated to be 0.37 in the present fishing intensity for multiparous females, hard-shell and soft-shell males in the Sea of Japan.<br>Soft-shell males were mainly less than 100mm carapace width and non-terminal molt regardless of carapace size, and terminal or non-terminal molt cannot mate with multiparous females. It seems that the abundance of recruitment to functional maturity males with hard-shell decreases due to the catch of soft-shell males.<br>It was ascertained that the optium sex ratio would be maintained at the present fishing condition for hard-shell males with fishing coefficient 0.5 year<sup>-1</sup> decreased effort for multiparous females and prohibition of soft-shell males catch.
日本水産学会誌 63(1), 30-34, 1997-01-15