The Return of the Adult Pacific Lamprey Offspring from Translocations to the Columbia River
Pacific Lamprey is a valuable species to tribal culture and to the ecosystem, but abundance in the interior Columbia River has been highly variable and muted in recent years. Translocation programs have been adopted as a proactive strategy to restore Pacific Lamprey abundance to the interior Columbia River, including the Snake River Basin, and these efforts have been largely successful in increasing larval and juvenile abundance in the recipient watersheds and further downstream. In this study, we show that not only have Snake River translocation offspring returned as adults to Bonneville Dam in numbers that exceeded model projections, but offspring from two other tribal translocation programs in the Umatilla (Northeast Oregon) and Yakima (South Central Washington) rivers have also begun to be detected in recent years with offspring produced across all three translocation programs estimated at approximately 1,065 fish in 2021. While Pacific Lamprey is known to lack precise natal homing which may limit benefits of translocations in the interior Columbia River Basin, evidence from detections in this study supports preference for interior Columbia River Pacific Lamprey to return home and migrate toward their natal basins. However, a portion of Snake River origin Pacific Lamprey was estimated to deviate from mainstem routes into tributaries including tribal ceded areas where tribal harvest occurs such as Sherars Falls in the Deschutes River. These results indicate benefits from translocation programs of Pacific Lamprey that not only increase abundance to targeted areas but will also increase tribal harvest opportunities for this culturally important species.
Hess, J.E., R.T. Lampman, A.D. Jackson, T. Sween, L. Jim, N. McClain, G. Silver, L. Porter, S.R. Narum. 2023. The return of the adult Pacific Lamprey offspring from translocations to the Columbia River. North American Journal of Fisheries Management. Online at https://doi.org/10.1002/nafm.10922.