Genetic Evaluation of Steelhead Trout (Oncorhynchus mykiss) in the Rock Creek Watershed of the Middle Columbia River Basin
This report summarizes a genetic evaluation of steelhead trout in Rock Creek and Squaw Creek (a tributary of Rock Creek) in the Middle Columbia River Basin. The watershed supports both anadromous steelhead and resident O. mykiss, and is part of the Mid-Columbia Evolutionarily Significant Unit (ESU) for steelhead, currently listed as “threatened” under the Endangered Species Act (Busby et al. 1996). However, status of Rock Creek steelhead is unknown (WDF and WDW, 1993). Rock Creek summer steelhead are wild origin and presumably distinct from other mid-Columbia stocks based on geographic isolation of the spawning population (WDF and WDW, 1993). Adult fish begin migrating up the Columbia River from May to November, and spawning occurs in the Rock Creek watershed from February through April. Juvenile life history information specific to this watershed remains largely undocumented (Lautz 2000). Anadromous steelhead trout are known to occur in Rock Creek up to 1/4 mile above the confluence with Quartz Creek, and in Squaw Creek up to the confluence with Harrison Creek.
Matala, A. P. 2011. Genetic evaluation of steelhead trout (Oncorhynchus mykiss) in the Rock Creek watershed of the middle Columbia River Basin. Appendix in Annual Report to the Bonneville Power Administration, Project 2007-156-00. Columbia River Inter-Tribal Fish Commission Technical Report 12-06, Portland, Oregon. 15p.