INFLUENCE OF TURBIDITY ON SWIMMING BEHAVIOR OF ISOLATED AYU IN STATISTIC WATER

Abstract

 The water includes turbidity during and after the flood. Almost fish uses eyes and lateral line during swimming, so that the turbidity may affect on the swimming behavior of fish. Fish trajectories in openchannel flows with turbidity are not known. In this study, the trajectories of ayu, Plecoglossus altivelis altivelis, in static water with turbidity were recorded with a digital video camera and trajectories of an each time were analyzed. It was found that the swimming velocity decreased with an increase of the turbidity, because visibility decreased with an increase of turbidity. The turning angle during swimming is almost constant irrespective of the turbidity.