Clearwater River Steelhead at the River/Reservoir Interface

Comparisons of historic ladder counts at Lewiston Dam, removed in 1973, with current counts at Lower Granite Dam suggest Clearwater River steelhead migration patterns have shifted in the last 42 years.  Current information collected at Lower Granite Dam gives us understanding of current migration patterns as steelhead leave the hydrosystem, but provides no data on steelhead interaction with the upstream reservoir and fisheries prior to entering the free-flowing Clearwater River.  In 2013, we radio tagged 70 adult hatchery origin Clearwater River steelhead at Lower Granite Dam.  The objectives of the study reported here were to: 1) describe timing of escapement into the free flowing Clearwater River; 2) describe residence time of steelhead in the Lower Granite Pool and in the slack water portion of the Idaho fishery; and 3) describe shifts in adult migration patterns relative to historical data.  Passage of steelhead above the fixed site was unimodal and median passage time was in early November.  Conversely, historical data indicate a bimodal movement pattern into the lower Clearwater, with approximately half the fish entering the Clearwater during spring.   This paper will also include results from the 2014-2015 tracking season, as those data are currently being collected.