| The swimming physiology of freshwater sculpins (Cottus pollux) on ramp fish passage was observed using ultra-high speed cameras. The swimming loci of fish were traced by motion capture system and their movement distance and speed in the fish passage estimated. In addition, two-dimensional flow velocity distribution and flow fluctuations are measured using a PIV (Particle Image Velocimetry) system. More than 60 boulder arrangements of ramp fish passage were examined to consider the optimum flow based on their swimming physiology. The fine spaces between boulders that matched their body lengths and sufficient hight of boulders that matched their body hight were required to maintain balance in high flow velocities. In most of the experimental cases, they lose their swimming balance and fail to migrate in boundary flow currents and in the turbulent water around boulders. And the roughness on the surface of floor board is effective for sculpin’s migration. |
