W. Nicholas Beer
Columbia Basin Research
School of Aquatic and Fishery Sciences
University of Washington
Box 358218
Seattle, Washington 98195
30 September 2008
Summary
The Adult Upstream Migration (AUM) model (CBR 2008a) makes daily, in-season predictions of the destination of fish that have arrived at BON. It requires stocks to be distinguished at BON by destination on a daily basis. In 2007, we began to use the historic passage patterns of PIT-tagged fish and visual counts to make this real-time prediction. Annual PIT-tag returns at BON, MCN, IHR and PRD were used to compute total returns to upstream zones. First, the difference in visual counts between MCN and BON were used to estimate the LCO returns. Second, the “within-zone” passage distribution (of PIT-tagged fish) was weighted by visual count numbers to determine the daily counts heading to a destination.
Recognizing that Chinook run timing has both genetic and environmental elements (Beer 2007; Anderson and Beer in review) we can refine this process further. In 2008, we began predicting the timing of the spring Chinook run at Bonneville using a genetic and environmental timing model along with in-season corrections based on environmental conditions and observations of passage (CBR 2008b).
For the 2009 passage season, this process is further refined. Adult Chinook timing and abundance is related to Jack-Chinook timing and abundance, therefore the timing model can be used to predict the annual offset of the run timing compared to the arrival day average. Timing offset are a function of stock compositions and environmental conditions during winter and early spring, so the stock separation fractions can shift as well. This analysis: 1) identifies differences and similarities between the PIT-tagged fish arrivals and the run as a whole, 2) generates a method to predict stock separation based on PITtagged returns to verify consistency in timing differences and upstream travel rates, 3) uses visual counts and passage timing to obtain run timing distributions, and 4) recommends the technical methods for refining the AUM stock separation process during in-season runs.