Movements of Bull Trout Relocated Above Albeni Falls Dam, Idaho

Dams built without a means of fish passage such as Albeni Falls Dam, constructed on the Pend Oreille River, ID in 1955, block fish migration to their natal tributary. The blockage of historical migration routes used by bull trout Salvelinus confluentus was a contributing factor to declines in their population.  Bull trout were listed as a threatened species under the Endangered Species Act on 10 June 1998. The objectives of this study were to provide bull trout passage around Albeni Falls Dam, predict natal tributary from genetic samples, and track the movements of the tagged fish to determine if the tributary entered during the spawning period matched the genetically predicted natal tributary for each fish. Eight bull trout were captured below Albeni Falls Dam. Each fish was surgically implanted with a transmitter and released upstream of the dam. To determine the most probable natal tributary of each bull trout,  a genetic sample from each fish was compared with databases of known bull trout populations located between Albeni Falls Dam and Thompson Falls Dam, MT. Movements were monitored using radio and acoustic telemetry via twelve fixed receiver stations (four at Albeni Falls Dam, one on the Priest River, two near Dover, ID, one on the Pack River, and one on each of the major bull trout producing tributaries of Lake Pend Oreille: Lightning, Trestle, Gold, and Granite creeks) and mobile tracked via vehicle, boat and aircraft. Seven of the eight tagged bull trout migrated past the receiver stations leading into Lake Pend Oreille and one fish traveled up the Priest River. Five of the fish transmitters were detected in the predicted natal tributary. Of the three tags not detected in the predicted natal tributaries, one fish was located in Lake Pend Oreille, one fish has not been located since entering the lake, and one fish was last detected in the Priest River. Results are part of an on-going study and indicate bull trout that are provided passage upstream of Albeni Falls Dam attempt to return to their home tributaries to spawn. Providing passage upstream of Albeni Falls Dam reduces losses to populations and protects genetic integrity of native bull trout in the Pend Oreille Basin.