2008 Volume 52 Pages 1207-1212
Fish sometimes enters into an intake gate of weirs and dams, so that a lot of released larval ayu and salmon are lost. Some techniques with electricity, transmitted light and air bubbles have been developed to avoid fish from the intake gate. However, a lot of fisheries co-operative associations pointed out that most of such techniques have no effect. In this study, the color types of transmitted light are changed at both sides of a rectangular water tank and swimming area of Zacco platypus and Zacco temminckii are observed. It was found that the color types do not affect on the swimming behavior of both fish.
Generally, it is known that fish avoid the area which is included air bubbles. In this study, the air bubbles are injected from the channel bottom and trajectories of fish are observed. It was found that air bubbles do not affect on the swimming behavior of Zacco platypus and Zacco temminckii.
