Author(s): Kouki Onitsuka; Takayuki Nagaya; Makoto Higashino; Tohru Takami; Noriharu Otsuka; Juichiro Akiyama; Hiroaki Ozeki; Kazuya Matsumoto; Yoshiki Shiraishi
Linked Author(s):
Keywords: Environmental assessment; Plecoglossus altivelis; Spawn; Suitability index
Abstract: It is well known that ayu, Plecoglossus altivelis, spawns at the rapid in the lower reaches of rivers. However, suitable conditions, such as the flow depth and velocity, for spawning of ayu are not known, so that the high accurate environmental assessment, i. e., PHABSIM, can not be conducted. In this study, preference curve of the flow depth and velocity for spawning of ayu were investigated on the basis of the field survey and previous data. It was found that the flow depth is not important than the velocity, and also that the velocity near the river bed is more important than the bulk mean velocity, due to ayu spawn on the river bed. The preference curve of the velocity for spawning of ayu can be obtained.
Year: 2005