アユは河床型をいかに利用するかアユの密度と体長分布

概要

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We have been continuing the ecological studies of a salmon-like fish, Plecoglossus aliivelis, or Ayu in Japanese, in the River Ukawa, which drains in to, the Japan Sea in the north-western part of Kyoto Prefecture. This paper concerns how the different river-beds were utilized by this fish in the summer of 1956. Generally speaking, population density of this fish in the residential season, which follows the up-stream migratory season, is the highest in the Hayase-rapids of boulder bottom, and the lowest in the Toro-pools of shallow sandy bottom. In the Hayase-rapids and Huti-pools with rock walls, there are both highly and lowly utilized ones by this fish. On the other hand, the Hirase-rapids of stone and gravel bottom are utilized uniformly. While the Hayase-rapids are occupied by both large and small fishes, the Hirase-rapids and Toro-pools are in general the habitats for smaller fishes, and Huti-pools for larger ones.
公益社団法人日本水産学会の論文