魚類の游泳生態に関する研究-I : トビウオの羅網方向について

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The author considered that the subject of behavior of oceanic surface fishes give clues to settle the problem of locomotion, gathering and scattering of fish school. How do fishes hold their position against movements of water masses and partial water currents? As only a few investigations regarding the above problem have been already carried, more investigations are expected in the near future. The author examined the relationship between the side of the net on which the fishes were entangled and the direction of water current. This gave the following results;…… 1) In the case of the investigation carried out during the daytime in the area over 30 miles off shore, over 95-99% of the number of the catches were entangled to the net on the tide ward side, and small number on the lee tide side. 2) In the allied case carried out during the daytime in the coasting area less than 15 miles off shore, in general, majority of the catches were entangled to the net on the tide ward side, as much as 78% and the rest from the lee tide side, however, very few cases should be high percentage on the lee tide side. 3) In the off shore area over 30 miles, the investigations during the daytime (involving the daybreak and twilight) were carried out in June and July. It is supposed that the flying fish would move keeping the direction of body parallel to that of the current.