Adult
Upstream Model and Escapement Forecaster
In 2002, the adult upstream "real time" forecaster was developed to predict the current season's adult salmon run size at Bonneville Dam and run timing from the Bonneville Dam Tailrace to the upstream dams on the Columbia and Snake Rivers. The forecaster consists of the Escapement Forecaster that predicts the arrival timing and run-size of adult salmon at Bonneville Dam and the Adult Upstream Model that predicts the passage timing of the fish at dams above Bonneville Dam. Each day during the spring and fall chinook runs, the predictions are updated on the web.
The Escapement Forecaster predicts the arrival timing of the run at Bonneville Dam similarly to the smolt RealTime prediction algorithms. Using pattern matching algorithms, it compares the inseason adult visual counts at Bonneville Dam to the historical counts (data courtesy of the U.S. Army Corps of Engineers, NWD) to predict the percent of the run that has passed Bonneville Dam on the current day and to project the remaining timing of the run. The Escapement Forecaster also makes run-size forecasts for Bonneville Dam. The pre-season run-size forecast is based on jack counts of the previous year. During the season, we predict run-size with 90% confidence intervals using a Bayesian algorithm with lognormal predictive density and with the pattern match forecast as a prior distribution. There is a blending routine based on Julian date which smoothly switches from the jack-based prediction to the pattern match prediction. There is also a three-day weighted smoothing routine to minimize the effects of daily count fluctuations.
Starting with the 2005 Adult Fall Chinook Run Size forecasts, a new method was employed to calculate the 90% confidence intervals for the next day cumulative run forecast and the final day total run size forecast. Mean squared error (MSE) of the total run forecast was calculated using deviations of actual runs from run predictions made for each day in all historical years since 1982. Run predictions were generated using the same methods employed for the current year's forecast. MSE is used to estimate the standard error and 90% confidence intervals (depicted by the gray lines -) of the run forecast. These same methods are applied for the next day cumulative run size forecast.
The Adult Upstream Model takes the projected escapement at Bonneville as input and predicts the arrival timing at dams above Bonneville Dam. The model contains a temperature and flow based submodel for reservoir passage and submodels for dam passage, fallback, and straying. In addition, the model uses a standard bioenergetic model to predict the fish energy consumption against the current during migration. River flow and temperature are modeled with the smolt passage model (see Water Quality Inseason Forecasts).
The Adult Upstream Model has been calibrated to radio tag data1 as well as all adult PIT-tag returns detected at Bonneville (started in 1998) and all available upstream detection sites (McNary, Ice Harbor, Lower Granite, Priest Rapids, and Wells).
Stock Specific Migration Timing
For information on the preseason forecasts and methods, please refer to Columbia River preseason adult spring Chinook run size and arrival timing predictions, 2008.
Since 2005, the Daily Run Size & Passage Prediction (Date-based) is for the period March 15 - June 15 to best match the Columbia River Fisheries (CRM) spring management period. The CRM 2008 Spring Chinook Forecast is 269300 fish.
Starting with the 2005 migration season, the Passage Predictions are available for four stocks: Snake River, Upper Columbia River, Lower Columbia River, and Hanford Reach/Yakima. Percent of the run arriving at Bonneville Dam is based on historic run timing and observed visual count data (courtesy of U.S. Army Corps of Engineers, NWD). Stock separation of the run at Bonneville is based on stock composition, reach conversion rates, and run-timing of selected PIT-tagged stocks for all available years of adult detections at PIT Tag observation sites.
Adult Upstream Model and Escapement Forecaster Performance
We applied our Escapement Forecaster algorithm and our Adult Upstream Model to adult passage counts for 2003.
Figure 1 Compares the cumulative run size as predicted on 4/24/2003 to the observed cumulative run size for 2003 spring chinook. Note: the preseason run size prediction of 121388 fish is based on spring 2002 jack counts. The arbitrary cut-off date of 5/31 for spring chinook to pass Bonneville Dam complicates the prediction process.
Figure 2 Compares the observed cumulative run size for 2003 fall chinook to the cumulative run size as predicted on 9/12/2003. Note: the preseason run size prediction of 218149 fish is based on fall 2002 jack counts. The pre-season (jack based) predictor is far more robust for spring predictions than for fall. A few days of large returns around 9/6 followed by a lull, briefly fooled the pattern matcher into thinking the run was winding down.
Figure 3 Compares predicted and observed run timing at McNary Dam. The predicted run is made using the Bonneville escapement observed up to 9/12/2003 and projected thereafter (See Fig. 2) as an initial release distribution.
Figure 4 Compares predicted and observed run timing at Lower Granite Dam. The predicted run is made using the Bonneville escapement observed up to 9/12/2003 and projected thereafter (See Fig. 2). One source of error here may be in using Bonneville Dam escapements comprised predominantly of Hanford reach fish to establish a release distribution for Snake River fall chinook.
Figure 1. A comparison of observed and predicted total run size and run-timing for 2003 at Bonneville Dam for adult spring chinook.
Figure 2. A comparison of observed and predicted total run size and run-timing for 2003 at Bonneville Dam for adult fall chinook.
Figure 3. A comparison of observed and predicted run-timing for 2003 at McNary Dam for adult fall chinook.
Figure 4. A comparison of observed and predicted run-timing for 2003 at Lower Granite Dam for adult fall chinook.
1 Bjornn, T.C., M.L. Keefer, C.A. Peery, K.R. Tolotti, R.R. Ringe, P.J. Keniry, and L.C. Stuehrenberg. 2000. Migration of adult spring and summer chinook salmon past Columbia and Snake River Dams, through reservoirs and distribution into tributaries, 1996. 2000. Technical Report 2000-5. U.S. Geological Survey, Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Moscow, ID.
