日本近海に於ける長須鯨の分布及び習性に就て

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The present account on the fin whale in the adjacent waters of Japan is based on the monthly reports of the following companies in the period extending from 1928 to 1934:[table](1) The fin whale, Balaenoptera physalus (L.), is commonly found in the adjacent waters of Japan and has a great economic importance. In summer, its whaling ground is at the southern seas of the Kurile Is. (on both the Okhotsk and the Pacific side), while in winter it is caught in large numbers in Yellow Sea, the Korea Straits and its neighboring waters where abound in Euphausidae. (2) The fin whales are caught within the range of 2℃. to 27℃ in the surface water temperature, but majority of them are found between 2℃-15℃. They can stand a considerable variation of salinity (euryhaline species) compared with the allied species (sei whale, blue whale). They, therefore, can migrate far into Yellow Sea in the winter season when the salinity of the surface water is as low as 32.00‰ or even lower. (3) The breeding appears to be in the south-western seas of Japan (Yellow Sea, the Tusima-Kaikyo and its adjacent seas) and judging from the size of the foetuses measured at various shore-stations in the years 1928-1934, copulation may be presumed to take place chiefly in the season during December and January and the period of gestation covers about eleven or twelve months. (4) The averaged length of the fin whales caught in the years 1929-1933 is as follows: 841 females…17.0m 832 males…16.7m The female attains sexual maturity at the averaged length of 19.4m which fairly coincides with the results (20.0m) obtained in the Antarctic by N. A. MACKINTOSH and J. F, G. WHEELER, zoologists for the "Discovery" expedition. (5) The whales captured in the different regions decrease in size from north to south: thus; [table]Studies on the Fin-Whale, Balaenoptera physalus (L.) of Japan Since the fin whales migrate from north to south, the decreasing of average length means that the larger individuals are caught earlier in the season, that is, in the more northern waters. (6) During the summer season, the fin whale is widely distributed in the northern seas of Japan:-the neighboring waters of Hokkaido, the Pacific southern coast of the Kurile Islands, and it is reported by the Russian technician that the fin whale migrates far north into the Arctic Sea passing the eastern coast of Kamtchatka and the Bering Sea. Regarding the southward migrations of the fin whales in the adjacent waters of Japan the following two main courses may be presumed: (a) The majority of the above-mentioned fin whale herds pass through a strait of the southern Kurile Islands and enter the Okhotsk Sea. They going through the Soya-Kaikyo (La Perouse Str.), they get to the Japan Sea. The greater parts of these herds go down southwest along the coast of the Primorskaya Province and the north-eastern coast of Korea (some of them along the coast of "Honshu", the main island of Japan) and make their appearances in the neighboring waters of Tusima Is. and subsequently, as winter advances, they further spread widely in Yellow Sea until the coast of Haikung Tau Is. is approached. (b) The other course of southern migration may be as follows. The fin whale herds which appear in summer near the southern seas of the Kurile Islands (chiefly on the Pacific side) go southward along the east coast of Hokkaido and Honshu on the Pacific side as far south, for instance, as the coast of "Kishu" (Wakayama Prefecture) in autumn and winter. The latter herds (b) are less in number compared with the former (a). It is also well known that the fin herds which migrate south-west (a), consist as a rule, of the parents accompanied by their calves.
社団法人日本動物学会の論文
1935-06-15

著者

松浦義雄
農林省水産局海洋課

日本近海に於ける長須鯨の分布及び習性に就て

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