On the Relationship between the Ocean Currents and Fluctuation in the Sardine Catch off Shimane Prefecture

Abstract

When the season of drift netting for the large sized (oba) sardine, Sardinia melanostica off Shimane Prefecture comes as late as the end of March in stead of January as it usually does, the fishing in this part of the Sea of Japan would turn out very slack. The fishing situation seems to depend mostly on whether the sardine would approach inshore in the early part of the season.
The present study has been made in regard to the relationship between the fluctuations in the ocean curients and in the sardine catch off the prefecture. The number of drift bottles which was liberated off the eas ?? ern coast of Korea in the successive winter from 1926 to 1934 and recovered on the northwestern coast of Japan has been assumed to represent the index of fluctuation in the ocean current flowing southward along the peninsula to reach that region of this country. The results may be summarized as follows:
1. The rate of drift bottles recovered on the coast of Shimane Prefecture after their being released off Kogendo in November seems to be in corrclation with the amount of large sized sardine landed at Emoto during the fishing season from February to April of the following year (Table 1). Correlation coefficient may be expressed as r=+0.67 at the 5% significant level.
2. In the years when the warm current prevailed along the coast, the recovery index of the drift bottles was found decreased just as the catch was scarce off the coast of Shimane Prefecture and other regions south of the Noto Peninsula, Ishikawa Prefecture. On the other hand, when the cold current developed with the greater index of the bottle recovery, the fishing prospered in the sea off these regions but dwindled in the northern prefectures (Table 2).
3. It may be concluded that when the warm current flowing northward prevails along the Japanese coa ?? t of the Sea of Japan, the sardine do not likely approach toward the shore.