Evaluation of Upstream Migration and Dam Passage By Adult Pacific Lamprey in the Lower Snake River, 2014

Dam passage is a potential factor limiting adult escapement to upstream locations throughout the Columbia River system potentially leading to declines in interior populations. During 2014, 254 adult lamprey were captured at John Day Dam on the Columbia main stem, implanted with radio transmitters and released at Ice Harbor Dam on the lower Snake River.  One-hundred, sixty-nine of these fish were subsequently detected at Ice Harbor Dam (87%; 169/194), 52 were detected at Lower Monumental (20%; 52/254), 19 were detected at Little Goose (7%; 19/254) and 8 were detected at Lower Granite dams (3%; 8/254). Dam passage ratios by project are 53% (41/78) for Ice Harbor dam, 62% (29/47) for Lower Monumental dam, 56% (10/18) for Little Goose dam and 63% (5/8) for Lower Granite dam. Passage rate for all four dams combined is 3% (5/151). Detections were used to calculate percent approach, relative entrance and fishway use, entrance and fishway passage success and passage times for each passage zone within a given dam. These metrics were used to identify primary entrances, fishways, and turn around zones used that may act as passage barriers. This project identifies potential passage bottlenecks and opportunities for future fishway enhancements in the Snake River.