透過性パイプを用いた小段式台形断面魚道の提案とその効果

抄録

Recently, Yasuda et al. have proposed the fishway with small steps in trapezoidal cross section for the migration of benthic fishes and crustaceans (i.e., shrimps and crabs). In this case, as the fishway has a slope of V 1: H 3 and a rest pool for swimming fishes may not be formed at each step, it is difficult for swimming fish to migrate at the upstream through the fishway. For the design of fishway, an economical fishway for the migration of multi-aquatic animals is required.

This paper presents the proposal of fishway with porous pipes settled on small steps in trapezoidal cross section for the migration of multi-aquatic animals. Further, the authors show the effect of the fishway on the migration of multi-aquatic animals such as diadromous crabs, shrimps, and swimming and demersal fishes. By using the video camera, hourly changes of the number of diadromous crab and shrimps i.e., crustaceans were recorded for the upstream migration via the fishway during a 15-hour period at the end of the summer in 2004. The field investigations revealed that juvenile shrimps, crab, and fishes could migrate easily upstream and downstream on the fishway. Further, the velocity distribution around the proposed fishway has been shown under the condition in which multi-aquatic animals could migrate at the upstream.