オイカワ幼魚の生息場所利用について

抄録

The utilization of habitat by young pale chub, Zacco platypus (TEMMINCK et SCHLEGEL) was investigated at 21 points in five types of river beds : the shailow pool, the side of shalow pool, the slow rapids, the side of slow rapids, and the submerged plant bed at River Kamo, Kyoto, Japan. In the shallow pool in summer it seemed that the young fishes kept swimming positions stable up to the rather same velocity of running water in the bottom layer as in the surface and the middle layers, and that velocity increased with growth. In autumn only at the points near the shore the density increased in the daytime, in proportion to the differences of water temperature between those points and the centers of the stream, and then the food-intake of one fish was less near the shore of the side of shallow pool than in the shallow pool. These results suggest that the patterns of the distributions or velocity or running water and water temperature among minor habitats in the river bed are important for deciding the utilization of habitat by young pale chub.