Migration behavior of adult Pacific lamprey in the lower Columbia River and evaluation of Bonneville Dam modifications to improve passage, 2002

Adult Pacific lamprey (Lampetra tridentata) encounter various obstacles to upstream migration at lower Columbia River hydropower dams. In particular, radiotelemetry studies indicate that lamprey have the greatest difficulty negotiating fishway entrances, collection channels, transition areas, and areas at the top of fishways. In 2002, we continued a study to evaluate the areas at dams where lamprey passage could be improved. Specific objectives of our research were to: 1) Evaluate passage efficiency of radio-tagged adult Pacific lamprey at Bonneville, The Dalles, and John Day Dams on the lower Columbia River. 2) Evaluate effects of structural and operational modifications on passage of adult lamprey at the lower Columbia River dams. 3) Determine fates of radio-tagged adult lamprey that do not pass Bonneville Dam. 4) Develop and evaluate a structure to pass adult lamprey from makeup water channels to the forebay at Bonneville Dam. Contract no. E96950021