瀬戸内海に於ける鮹の漁獲高と降水量及び気温との関係に就て
1935 年 4 巻 4 号 p. 253-258
詳細
1935 年 4 巻 4 号 p. 253-258
The fishery of Octopod, mostly of Polypus vulgaris (Lamarck), is economically very important in Japan. This animal inhabits littoral zones of our country and occurs very abundantly in Inland Sea. Its breeding season extends from late July to early October in this region, and it lays eggs among rocks or sea-weeds grown in shallow water. Since such habit of this animal suggests a conjecture that the size of the catch of it may be influenced by various meteorological and oceanographical factors, the size of the catch of this animal was studied in reference to precipitation and air-temperature in three of the prefectures surrounding the Inland Sea, viz., Hirosima, Kagawa and Okayama, where comparatively good statistical data are available. Of these three, the prefecture Hirosima is very remarkable and pref. Kagawa is less so in showing significant correlation between the catch in question and precipitation in certain months of the previous year, but not at all in pref. Okayama, as shown in the following lines.
Months of the previous year, the precipitation of which were taken into consideration. Hirosima. Kagawa. Okayama.
July, Aug, Sep. -0.423±0.142 -0.691±0.068 -0.024±0.172
Aug., Sep., Oct. -0.878±0.030 -0.373±0.142 -0.010±0.171
Sep., Oct., Nov. -0.822±0.056 -0.614±0.108 -0.145±0.169
The coefficients of the partial correlation between the above mentioned two items in the prefectures of Hirosima and Kagawa, keeping air temperature during the same season constant, are not significantly different from those of the ordinary ones. Thus, it appears that the precipitation during the breeding season of a certain year has much influence on the size of the next year's catch of the octopod in the two prefectures, especially in Hirosima. My ?? esults may be said to stand in harmony with the fact that the newly hatched octopod reaches marketable size after a lapse of about one year in these two prefectures. The absence of the correlation between the items in question in pref. Okayama appears to be due to inadequacy of the satistical data obtained there.
