エトロフ島沿岸で採集されたシロザケ大型幼魚〔英文〕

概要

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To determine if the nearshore waters of the southern Kuril Islands are a migration route of juvenile chum salmon originating from the rivers of Japan, waters near Iturup Island were sampled with a purse seine. Two of the purse seine sets in early August captured 16 grown juveniles. Based on a detailed examination of 14 of these juveniles, the mean size was 187.3mm fork length and 62.5g body weight, the number of gill rakers was 23.8, the mean number of circuli on the scales was 21.0; and the maximum radius of scale was 0.85mm. Examination of stomach contents indicated that Copepoda, Amphipoda, and Euphausiacea were major food items, but that the amount of food in the stomachs was extremely low. The mean number of circuli on the scales indicates that the juveniles emerged between mid-December and mid-March, suggesting that they originated from rivers in Hokkaido or Honshu. The results of the present study also show that some jnveniles migrate in nearshore waters of the southern Kuril Islands to reach offshore waters of the Bering Sea and North Pacific Ocean.
日本水産學會の論文