ゴマサバの海域別産卵期の考察

概要

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On the spawning season of mackerel, P. tapeinocephal?s and its apt water-temperature in the fishing-grounds of East China Sea (south of 29°N lat), Satsunan and Izu, some investi-gations were carried out examining the state of the gonad index (G. W./B. L.3×103), the collected larvae, and the sea conditions of the fishing grounds. The results obtaind are as follows: (1) In the East China Sea, Satsunan (South Sea off Kagoshima Prefecture) and Izu fishing grounds, the spawning-season, the best time for spawning, water-temperature were ascer-tained as shown in the following list. Spawning-season Best time for spawning Water-temperature East China Sea: Jan.-May Feb.-Apr. 18-23°C Satsunan: Jan.-June Feb.-Apr. 17-23°C Izu: Feb.-June Mar.-May 17-23°C (2) The spawning mackerel of January in Satsunan is such large-sized as beyond 34cm in fork length and that of February in Izu is such one as beyond 37cm in fork length. (3) In the fishing ground of East China Sea, Satsunan and the around off Miyakejima, P. tapeinocephalus seems to become mature at the term when the water temperature begins to rise from the lowest degree.
社団法人日本水産学会の論文