Development and application of a genetic baseline to inform bull trout (Salvelinus confluentus) passage and conservation in the Snake River

Hargrove, J.S., Delomas, T.A., Campbell, M.R. et al. Development and application of a genetic baseline to inform bull trout (Salvelinus confluentus) passage and conservation in the Snake River. Conserv Genet (2024).

Bull trout conservation in Hells Canyon | Idaho Fish and Game

Barriers to upstream migration, such as dams, limit fish dispersal in lotic systems, including the federally protected bull trout (Salvelinus confluentus). The Hells Canyon Dam on the Snake River currently prevents upstream passage of migratory bull trout into tributary systems in Idaho and Oregon, USA. Viability modeling previously identified the influx of a small number of migrant bull trout as the most important variable for increasing population persistence of resident bull trout populations occupying headwater tributaries above Hells Canyon Dam. Migratory bull trout that overwinter in the Snake River below Hells Canyon Dam could potentially serve as a source of migrants via upstream passage; however, the origin of these fish and their genetic relationship to populations above Hells Canyon Dam is unknown. To address these knowledge gaps, we genotyped bull trout from Idaho and Oregon and developed a genetic baseline to identify the population origination of migratory bull trout below Hells Canyon Dam. An assessment of genetic baseline performance found that stock assignments were highly accurate and minimally biased. Genetic stock identification assigned 97% of the migratory bull trout captured below Hells Canyon Dam to the Imnaha River basin, a large bull trout population located below Hells Canyon Dam. No bull trout were assigned to populations above Hells Canyon Dam. Moving forward, the bull trout genetic data described here can serve as a baseline for future monitoring and conservation efforts in the transboundary waters of Oregon and Idaho and help inform select bull trout passage and translocation efforts.