Abstract
In 2014, we continued a multi-year study to evaluate and improve adult Pacific lamprey passage at Columbia River Dams with the following objectives: 1) Determine lamprey use of Bonneville Dam lamprey passage structures (LPSs) located at the auxiliary water supply channels. 2) Assess the effects of providing refuge areas at auxiliary water supply channels and fishways. 3) Determine lamprey use of the Bonneville Dam LPS located at the Cascades Island fishway entrance. 4) Develop methods to collect lamprey from the makeup water supply channel at Cascades Island. 5) Develop methods to enumerate lamprey entering a newly-installed trap at the south fishway of John Day Dam. 6) Design, build, and test lamprey use of an experimental wetted wall at Bonneville Dam. To achieve these monitoring objectives, we used two approaches. First, we estimated individual lamprey passage in the existing structures. For these estimates, we used lamprey-activated counters in the Washington Shore, Bradford Island, and Cascades Island AWS structures.