隠岐島周辺に於けるスルメイカの漁況学的研究-II : 気象並びに月齡と漁況との関係について

概要

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In the previous report the discussion concerned with relationships between the squid catch by fixed nets and meteorological factors, such as low pressuse, discontinuity, wind and air temperatures. The present study deals in the relationships of the catch with the rainfall, cloud, and age of the moon. 1) Chi-square test on the rainfall proved that the rain falling more than 5 mm. a day had an adverse effect upon the squid fishing for a day or two after the raining. As far as the rain did not fall more than 10mm. a day, terrestrial water flowing into the sea affected but little the fishing. However, as most of the light rain came along with the cold front, the wind seems to have brought an additional effect on the fishing (Table 1, Figs, 1, 2). 2) The fishing was likely affected when the cloud had increased on the preceding day (Table 2). 3) During the full moon with the moon age of 10 to 20 days, the squid would swim about in waters much closer to the surface with a wider range of activity than in the first quarter when the moon age is 24 to 4 days. For this reason, set nets, c, placed at the inward of Urago Bay, had a greater catch of the mollusk than those a, at the mouth of the Bay. Whereas, catch of the nets at a was better than at c during the first quarter because of the squid loitering around the entrance of the area. Illumination of the moon is probably the most decisive factor controlling the habitual movement of the squid (Table 3, Fig. 1).