MIGRATION CHARACTERISTICS IN POOL-AND-WEIR FISHWAY WITH SINGLE AND MULTIPLE FISH SPECIES

Abstract

 Many experiments have been conducted to determine the optimum fishway standard on the basis of the migration rate of a single fish species released near the entrance of a fishway. However, fish try to migrate in the fishway surrounded by other fish species. In this study, the migration experiments in the pool-and-weir fishway were conducted as single or multiple species of Plecoglossus altivelis, Opsariichthys platypus and Misgurnus anguillicaudatus. In the single species condition, each species formed a school of fish at its preferred velocity and attempted to migrate upstream. In the multiple species condition, all fish species changed their schooling position as compares with that of single species. The school of P. altivelis moved to the low velocity zone, while O. platypus and M. anguillicaudatus were pushed away from the P. altivelis school. On the other hand, O. platypus are pushed into the high speed velocity area and become more motivated to migrate upstream.