Theses and Dissertations Collection

Steelhead Oncorhynchus mykiss is a species of high economic value and supports popular sport fisheries across the Pacific Northwest. The Clearwater River, Idaho, provides a trophy steelhead fishery and is home to wild- and hatchery-origin steelhead. Given the lack of information on the spatial and temporal overlap of wild and hatchery steelhead, as well as anglers, in the Clearwater River, radiotelemetry was used to describe the distribution of steelhead, and creel surveys were used to describe the distribution of anglers. In total, 289 wild (Potlatch River and Lochsa River) and hatchery (Dworshak and South Fork Clearwater River – local brood and general production) steelhead were radio tagged at Lower Granite Dam from September 2016 – June 2018. Steelhead were tracked in the Clearwater River using mobile tracking surveys (boat and vehicle) and 12 stationary antennas. The majority of wild and hatchery steelhead arrived in the Clearwater River in the fall with the exception of Lochsa River steelhead which arrived in the fall and following spring. Average daily movement of steelhead was minimal (mean = 0.3-4.7 km/d) and dependent on water temperature and flow. Steelhead were primarily detected in run habitats. Habitat use was partially related to season and length and age of steelhead. Wild and hatchery steelhead returned at high rates to their natal tributaries and release locations. Fates of wild and hatchery steelhead varied with fish either returning to spawning grounds, harvest by anglers (i.e., hatchery fish), or their fate was unknown. No straying was observed for wild or hatchery steelhead; however, steelhead overshooting their natal tributaries and release locations was documented. Spatial and temporal overlap of wild and hatchery steelhead was minimal. Anglers overlapped with hatchery steelhead in the fall, winter, and spring. Overlap of anglers and wild steelhead was minimal and largely occurred in the fall in the lower Clearwater River.