牡鹿半島周辺海域における海洋生活初期サクラマスの卵巣発達

概要

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Ovarian development of masu salmon during their early marine phase was characterized by measuring gonad weight (GW), gonadosomatic index (GSI), oocyte diameters and making histologi-cal observations. GW increased with fork length (FL). GSI showed small seasonal changes. Oocytes at the late peri-nucleolus stage were the major component in the ovaries of individuals less than 15cm FL. The distribution pattern of oocyte diameters was unimodal. It was assumed that this was the stage immediately after migration from a river to the sea. Oocytes in the yolkvesicle stage were detected in ovaries from individuals 15-30cm FL. The distribution pattern of oocyte diameters was unimodal. This stage was assumed to be the beginning of the northward migration phase. Oocytes in the oil drop stage were seen in ovaries from individuals over 20cm in FL, and the distribution pattern of oocyte diameters was bimodal.
日本水産學會の論文