The Constitution of Wheale Populations in the Antarctic:I. Blue Whale

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概要

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• The present account deals with the results of direct observations on the whales brought into the floating factory "Kyokuyô-maru" during the Antarctic season 1938/1939 in the whaling ground (so-called Area IV). During the period extending from 16th November 1938 to 15th March 1939, a total of 472 blue whales was examined. 1) The average number of corpora lutea of 113 mature female whales (the average length of which measured 24.98m.) was 7.69 (Tab. 7). It was seen from this that female blue whales averaged the same age during the 1926/27 season at South Georgia and during the 1938/39 season in the Antarctic Area IV. 2) The whales with only one corpus luteum were conspicuously dominant in number (Fig. 4). Of 16 such whales 8 were pregnant and 2 were lactating. Thus at least 10 (63 %) whales would be estimated as they were pregnant in the first breeding season and nearly the same results as mentioned above were obtained also in the whales with two or three corporalutea. Furthermore, as suggested by WHEELER (1930), since whales act collectively the number of unfertilized ovulations before pregnancy tends to be the same in any one season, and each peak of the frequency graph may be considered as representing an age group. From these facts, it might be tentatively concluded that the number of unfertilized ovulations before pregnancy, if any, must be far less in number than the figures (4-5) suggested by MACKINTOSH and WHEELER. 3) The proportion of mature to immature whales by the length of the whale was 56% to 44% respectively. These figures were nearly alike to those at South Georgia given by M. and W. during the season 1925/26-1926/27. 4) The apparent constitution of the stock i.e, the ratios of the different classes of whales examined might be summarized and compared with the results given by M. and W. at South Georgia as in the table on the preceding page. 5) Assuming that the onset of physical maturity in females coincides with the accumulation of eleven corpora lutea as was suggested by LAURIE (1937), the proportion of the physically mature females was found to be 30% of the sexually mature females and 14% of the total females.

著者

• 松浦 義雄

  農林省水産局

関連論文

• 南氷洋に於ける捕獲鯨の組成 : III. 座頭
• The Constitution of Wheale Populations in the Antarctic:I. Blue Whale
• タイトル無し
• Statistical Studies of the Whale Foetuses:I. Blue Whale and Fin Whale in the Antarctic

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