Snake River hatchery steelhead hatchery strays are considered a significant threat to recovery and persistence of Deschutes River steelhead populations.  The magnitude of straying that is occurring may pose a serious challenge to the continued genetic health and productivity of wild Deschutes steelhead.  Chilcote (1998) summarized data on the Deschutes River steelhead while conducting a conservation status review of Oregon steelhead.  His assessment of the status of wild Deschutes River steelhead suggested that they are at a serious risk of extinction.  He further speculated the likely cause of this risk may be a decrease in the reproductive capacity due to introgression with out-of-basin stray fish.  More recently, Carmichael et al. 2010 concluded that the proportion of naturally spawning steelhead that were hatchery origin in both the Eastside and Westside Deschutes River steelhead populations resulted in a high risk rating for the spawner composition metric in the viability assessments.  Some level of straying and gene flow occurs naturally in wild populations.  However, the level of this natural gene flow and straying is uncertain, and likely is at a much lower rate than is currently occurring in the Deschutes River.

Wild steelhead escapement to the Deschutes River declined significantly during the decade of the 1980’s and continued to decline through the late 1990’s.  The population decline in the Deschutes River and other Middle Columbia River tributaries prompted the National Marine Fisheries Service to list steelhead populations in the Middle Columbia Evolutionary Significant Unit as a threatened species warranting protection under the Endangered Species Act.  During the same period of time that escapement of wild steelhead declined, a significant increase in the number of stray hatchery origin steelhead was detected at several trapping and counting sites in the Deschutes River subbasin.  The number of stray hatchery steelhead captured at the Sherars Falls trap (river mile 44) peaked during the 1997-98 run when escapements of stray hatchery steelhead were nearly ten times that of wild steelhead.  Stray hatchery steelhead are either harvested in fisheries, leave the Deschutes River and continue their migration, or remain in the subbasin to spawn.  Stray hatchery steelhead remaining in subbasin and spawning naturally with wild fish, can impact the ability of the wild populations to maintain a discrete phenotype and genotype, and may cause a reduction in the fitness and productivity of the wild populations.  Since the inception of this project, rates of stray hatchery steelhead have reduced in scale but still pose a significant challenge to genetic health for Mid-C Steelhead.    

This project is in the final year towards sunset, expiring end of FY19 contract cycle, and objectives have been modified to maximize the benefit of eight years' of data collection.  They are to:  1) determine the impact of stray hatchery steelhead on the production of juvenile outmigrant steelhead ;  2) determine the number of stray hatchery steelhead escaping into the Bakeoven and Buck Hollow creeks, and  3) compare measures of fitness and productivity of the wild population and introgressed population.  Project objectives were achieved by operating juvenile and adult migrant steelhead trapping facilities in Bakeoven (treatment) and Buck Hollow (control) creeks.   Adult traps and weirs were used to determine adult escapements, and prevent hatchery steelhead from escaping into spawning areas in the each creek.  Selected life history traits, downstream migrant population estimates, and other indices of fitness were collected from downstream trapping facilities at both treatment and control streams, reported during this final year of project closeout.  Buck Hollow and Bakeoven creeks were selected as study streams due to their close proximity to each other, similar basin size, geology, and land use.   The two study streams are both significant spawning tributaries for wild Deschutes Eastside populations, and have very similar habitat characteristics and fishery resources. We chose to conduct this work in the Deschutes because of the importance of Deschutes steelhead to the Mid Columbia ESU and the magnitude of the stray problem in the Deschutes Basin.