Lauritzen, D.V.*; Hertel, F.; Gordon, M.S.: Kinematics of Salmon Leaping Up Waterfalls

Fish ladders have been used for hundreds of years to help migratory fishes move upstream past human-made obstacles such as dams. The designs of these ladders appear to have given little consideration to the behaviors and leaping abilities of the fishes they are supposed to help. These inadequate designs seem partly a result of the paucity of information on the behavior and biomechanics of fishes as they leap. We hope to integrate biological considerations with the design and construction of fish ladders by understanding the preferences, capacities and limitations of wild fishes leaping up natural stream obstacles. We analyzed aspects of the biomechanics of leaping in sockeye salmon as they passed two natural waterfalls during their spawning migration. Video recordings were used to track the fish as they traveled through the air and kinematic parameters of individual leaps were quantified. Stream characteristics were also measured in the vicinity of the leaping fish. These results are summarized along with calculated theoretical parameter values for successful leaps. We plan to conduct future studies correlating the hydrology downstream of waterfalls with leaping salmonid kinematics, both underwater and in air. These studies will experimentally investigate the preferences of migrating salmonids at stream obstructions. These results along with the theoretical model describing successful leaps may be used in the development of fish ladders to help maintain a natural passage rate of fishes up streams that contain human made obstacles. This study was funded by the Centers for Water and Wildland Resources project number W-928 and the UC Energy Science and Technology Program.