Correlation between Catches of Fishin Grounds and Secular Variation in the Catch of the Yellow-tail, Seriola quinqueradiata, along the Pacific Coast of Japan

Abstract

In the present paper, the correlation of the annual catch of the yellow-tail, Seriola quinqueradiata T. & S., between any two prefectures along the Pacific coast of Japan, and also the patterns of the secular variation of the catch, have been statistically analysed, based upon the data from the Statistical Tables of the Ministry of Agriculture and Forestry of Japan during the period between 1915 and 1954. Though the definitive conclusions have been unable to obtain, the followings are conjectured: 1) Fishing-grouds of the yellow-tail along the Pacific coast of Japan may be grouped into the following three regions, mainly based on the correlation of the fluctuation in the catch; A) The region including Iwate and Miyagi Prefectures. B) The region including Ibaragi, Chiba, Mie and Wakayama Prefectures. C) The region including Kanagawa, Shizuoka, Kôchi and Miyazaki Prefectures. The first, as seen in Fig. 1A, is waving in the pattern of secular variation, the second (Fig. 1B) being in gradual increase and the third, (Fig. 1C) in gradual decrease. 2) Both Mie and Wakayama Prefectures correlate positively with both Ibaragi and Chiba Prefectures. The abovementioned coincidence of the catch between the separated areas may probably be due to the topographical similarity that all of the prefectures are located along the coast of a peninsula, the former two prefectures and the latter two forming Kii Peninsula and Bôsô Peninsula, respectively (Table 1). 3) It is noteworthy that the positive correlation is highly recognized in any two prefectures lying in Kii Peninsula and to the south-west of the same peninsula. The reason may be assumed as follows: the region come under a returnable area, where part of so-called southing shoals migrate north again, though probably staying for a while in the region. In addition, the drime fishing season relatively coincides with each other, and thence the hydrographic or meteorological variaton, which is considered as one of the most important factors to influence the fishing, commonly affects each fishing-ground in the region.