Adult Passage Predictions based on Visual Counts for Combined Columbia and Snake River Stocks

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Peak Arrival & Run Size predictions for spring Chinook at Bonneville Dam started in 2008. These predictions begin with a preseason prediction of run timing from a Genetics and Environment Timing model1 and a preseason run-size prediction. The daily, inseason methods to simultaneously estimate distribution parameters from the observations-to-date include use of up-to-date environmental conditions, historical bounds on parameters, and the mathematical properties of the gaussian distribution. The complete run of Chinook in the Columbia River is the sum of three sub-runs—spring, summer and fall—each well characterized by a gaussian distribution. For more information, please refer to Run timing of adult Chinook salmon passing Bonneville dam on the Columbia River.

1. Anderson and Beer. 2009. Oceanic, riverine, and genetic influences on spring Chinook salmon migration timing. Ecological Applications. 19(8):1989-2003. Available from: