EFFECTS OF INSTILLATION LOCATIONS OF BOULDERS AT BOTTOM OF POOL-AND-WEIR FISHWAY ON MIGRATION RATE OF OPSARIICHTHYS PLATYPUS

Abstract

 It is important to keep suitable area by boulder in pool-and-weir fishway to make the migration rates of fish high. In this study, migrating behaviors of Opsariichthys platypus in pool-and-weir fishway were compared with instillation locations of boulders placed on the bottom of pool-and-weir fishway changed. Migration behaviors of Opsariichthys platypus were obtained with the aid of two sets of digital video cameras. It was found that Opsariichthys platypus migrates remarkably uses space between boulders when boulders were placed on the upper bottom in the pool. It is because the velocity of space between boulders is low compared to other space.