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Yakima River Summer Run Steelhead

Notes:

But before we jump into the model, a little bit of background review of Yakima River steelhead which are 100% of the Summer run race. In 1999 the mid columbia ESU was listed as threatened under the endangered species act which included all populations of steelhead residing in the yakima basin. Returning adults have been enumerated since the mid 80s in the lower portion of the watershed and have ranged from 450 to 4491 with an averaged of 1,773 wild adults. Depending on the source, historic abundance estimates range from 20,800 to 100,000 adult steelhead. 4 different or extant populations exist in the Yakima subbasin that include the satus and toppenish cr populations, Naches river population and the focus of todays presentation, the upper yakima population. Estimated 10 yr geometric mean number of spawners for each population include 568 for the satus pop, 148 for Toppenish, 462 for Naches and 92 for the entire upper Yakima which is the focus of the presentation today