THE BEHAVIOR RESPONSE OF JUVENILEARISTICHTHYS NOBILIS TO THE ACCELERATING FLOW DURING THEIR DOWNSTREAM MIGRATION

To investigate the ability of downstream migration of Juvenile bighead carp (Aristichthys noblis), a self-designed equipment with three inlet velocity (0.018m/s, 0.034m/s, 0.053m/s) was utilized. Results indicated that the passing rate under three inlet velocity were all 100%. Most fish used tail through first (tail-first) to pass the hole, especially under the high velocity, and the percentage of head-first was merely 6.25%. The total passing time in the low velocity was significantly less than the middle velocity (P<0.05), and no difference existed between the high velocity and the other two conditions (P>0.10). In regard to the passing time, from the time subject enter the accelerating flow field to the moment it left the experimental area, the carp appeared no significant difference (P>0.10) in all three conditions. These results indicated the impact the accelerating flow on the duration and methods of Juvenile bighead carp’s downstream action, which provide knowledge for fish passage techniques and preserve fish resources. In addition, this work established an available method to study the behavioral reaction fish fight accelerating flow during its downstream migration.