ECOLOGICAL AND OCEANOGRAPHICAL STUDIES ON THE PURSE SEINE FISHING GROUNDS AROUND OKI ISS.-I

1. The surface current in autumn of the purse seine fishing grounds around Oki Islands for the period, November, 1961 to February, 1962, was studied by means of drift bottles. 2. Out of a total of 450 bottles released, 119 (26.5%) were recovered. 3. Because of the prominence of the winter monsoon and then, of the wind-induced southwards movement of bottles, the distances of drift were rather short, almost all of the recoveries being made in the region to the west of Pt. Rokugo of Noto Peninsula with three exceptions. At the same time, durations between releases and recoveries were comparatively short, a half of ultimate recoveries being made within the first 20 days since release, and 97% within 60 days. 4. Corresponding to 74% of the total recoveries, the drift-speed was estimated as 0.1-0.4 knots, and in the case of bottles recovered in the sea-off as 0.8-0.9 knots. 5. The south-westwards surface current in the vicinal sea region of Saigo was not recognized in this period, and this was supposed to be the cause of poor catch of the purse seine fishing in this area in the season of autumn and winter, 1961.