Statistical Analysis of the Catch at the North-Eastern End of Suruga Bay. I:Bluefin Tuan (Thunnus orientalis T. & S.)
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概要
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The young bluefin tuna of I age-group are abundantly captured from April to June by the keddle nets along the southern coast of the north-eastern end of Suruga Bay. The catch of the young fish is first abundant on the western side and then on the eastern side. The arithmetic mean of the frequency distribution of the catch was computed for the western and eastern respectively and the median for each was also obtained. The value, (arithmetic mean)-(median), is thus positive for the eastern catch and negative for the western. The adult are mostly captured from the middle of March to the beginning of April, and also around the beginning of July, larger ones (beyond 100kg) being mostly fished in spring along the western part of the fishing area and relatively large number of smaller ones (below 100kg) in summer on the eastern side. The arithmetic mean of the frequency distribution of the daily catch of the young at the Sigedera fishing ground from March I to July 31, 1924 to 1932 shifts by degrees from the end of April until it reaches to the end of May and then abruptly goes back to the end of April or the beginning of May to start the lag again. The youngest bluefin tuna captured by the keddle nets in the fishing area measures about 20cm in length and is fished since the beginning of August. The duration of the fishing period of the young at the Sigedera fishing ground covers about 20 months of the life-span of the young fish with several maxima of the catches during this period. The period of the abundant catch of the young at this ground ranges from 12 to 17 days.
- 社団法人 日本水産学会の論文