- 著者
-
川村 軍蔵
不破 茂
- 出版者
- 鹿児島大学
- 雑誌
- 鹿児島大学水産学部紀要 (ISSN:0453087X)
- 巻号頁・発行日
- no.23, pp.p9-18, 1974-12
"Even when the fishing is carried out under the constant fishing effort, catch fluctuates largely. Its fluctuation depends on two main factors, i.e. phychophysiological phase of fish and the fish population size in the fishing ground. To clarify these factors, the analysis of the catch fluctuation is needed. By use of Auto-correlation Coefficient, the authors carried out the analysis of periodic fluctuation of the catch of spotted mackerel in the fishing ground off the Yaku Island in Kagoshima Prefecture. In this study, it was clarified that when the number of the catch per one operation is less than 25 fish, the catch depends mainly on the chance, and when it is over 25 fish, the catch depends on the fishing ability of the crew, which is fixed by the experience and the strength of the crew. Then, in this analysis, the authors used the catch-data obtained in 1971 and 1972, and of the crew who showed an average catch irrespective of the catch per one operation, and who was looked upon as the one with much experience and full strength. Moreover as the catch was supposed to be affected by the winds and waves because of the smallness of the fishing boat, the fluctuation of the scale of wind waves in the fishing ground was analyzed. The following results were obtained. (1). In the wind waves fluctuation, significant cycles consisting of 3.4 days, 5.2 days and 32.7 days were observed in 1972. (2).In the catch fluctuation, significant cycles consisting of 3.8 days and 8.8 days were observed in 1971; and those of 5.1 days and 9.6 days in 1972; and the former in 1972 was considered to be the cycle affected by the wind waves. (3). No cycle agree with that of the moon-age was observed in the catch fluctuation. (4). It was assumed that the periodic fluctuation of catch is to be caused chiefly by both emigration and the immigration of the spotted mackerel in the fishing ground round the Yaku Island."