北洋鮭鱒漁業の流し網にかかったイルカについて

• Main Authors: 水江 一弘, 吉田 主基
• Format: Report
• Language: Japanese
• Published: 長崎大学水産学部 1965
• Subjects: Bering Sea; Pacific
• Online Access: http://hdl.handle.net/10069/31536; https://nagasaki-u.repo.nii.ac.jp/?action=repository_uri&item_id=8744; https://nagasaki-u.repo.nii.ac.jp/?action=repository_action_common_download&item_id=8744&item_no=1&attribute_id=18&file_no=1

1) A great number of porpoises had been caught by the Japanese, salmon fishing gill nets in Bering Sea and the North Pacific Ocean except a few northern porpoise whales and minke whales. A salmon fishing fleet had caught more than 1,000 porpoises every year, and 11 Japanese salmon fishing fleets had caught more than 10,000 porpoises. These porpoises have hitherto not been utilized and have been thrown into the sea. 2) The porpoises thus caught belong to one species of the various kinds of the porpoises. Of 54 of them, the body color, body shape, external proportions, skull measurement, number of vertebrae, os costale, cartilago costale and the teeth were investigated, and their food and reproduction behaviors were surmised from their stomach contents and their uroganital organs (i. e. genital organs, mammary gland and fetus). As a result of these investigations, it was found that this species of porpoise is so-called DALL'S porpoise itself which DALL had caught in the adjacent water of. Adakh Is. in 1873 and TRUE had reported as Phocaena dallii TRUE in. 1889. 3) In 1911 ANDREWS found out, in the north-east coast of Japan, a porpoise (what we call "Rikuzen-iruka" in Japanese) and he named this porpoise Phocoenoides truei ANDREWS (TRUE's porpoise). And then he maintained that 'genus Phocaena' which TRUE had indicated in his report should be divided in two groups; 'genus Phocoenoides' should be established newly and Phocaena dallii be displaced by Phocoenoides dalli. The authors. will conform to this opinion. 4) The range in which this species of porpoises were caught is shown in Fig. 1. It seems that they exist in abundance in the sea area more eastern than Long. 175° W., but the Japanese salmon fishing factory ships do not operate in the sea area more eastern than Long. 175° W., so there is no report about this species of porpoises in that place. DALL's porpoise were caught in larger quantities by the salmon fishing gill nets in the adjacent water of the islands along the Aleutian Is'lands and in the east coastal ...