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Title: Monitoring and Evaluation of Smolt Migration in the Columbia River Basin, Volume IV : Evaluation of the 1998 Predictions of the Run-timing of Wild Migrant Yearling and Subyearling Chinook and Steelhead, and Hatchery Salmon in the Snake River Basin Using Program RealTime.

Technical Report ·
DOI:https://doi.org/10.2172/922249· OSTI ID:922249

Program RealTime provided tracking and forecasting of the 1998 inseason outmigration via the internet for stocks of wild PIT-tagged spring/summer chinook. These stocks were from eight release sites above Lower Granite dam, including Bear Valley Creek, Catherine Creek, Elk Creek, Lake Creek, Imnaha River, Minam River, South Fork Salmon River, and Secesh River. Forecasts were also provided for a stock of hatchery-reared PIT-tagged summer-run sockeye from Redfish Lake and for the runs-at-large of Snake River wild yearling and subyearling chinook salmon, and steelhead. The 1998 Program RealTime performance was comparable to its performance in previous years for the whole-season evaluations for every stock tracked. Relative to 1997, performance improved for the yearling chinook run-at-large, and for predictions for last-half of the season for every other stock. Performance compared poorly with 1997 predictions for the first half of the runs of PIT-tagged yearling spring/summer chinook stocks and the run-at-large of fall subyearling chinook, and was slightly worse for the first half of the Redfish Lake sockeye run and the steelhead run-at-large. Poor first-half performance was likely due to the unusually large (and in some cases short) outmigrations in 1998. Utilization in 1998 of a different method of adjusting smolt counts at Lower Granite Dam compared to previous years produced slightly better first-half performance than pre-1998 adjustments would have, but slightly worse last-half performance, for all the PIT-tagged stocks, prompting a return to the pre-1998 adjustment formula for the 1999 outmigration. An Army Corp of Engineers (ACOE) experiment during April and May of 1998 involving the installation of two new components to existing structures at Lower Granite Dam did not appear to affect RealTime performance. A comparison of run-timing predictions based on FPC passage indices and Battelle hydroacoustic counts showed the two independent data sources produced very similar results, for the wild steelhead and yearling chinook runs-at-large. Due to the less than desirable first half performance in 1998, a refinement in the calibration process for Program RealTime will be conducted in the future.

Research Organization:
University of Washington. School of Fisheries.
Sponsoring Organization:
US Bonneville Power Administration
OSTI ID:
922249
Report Number(s):
DOE/BP-91572-7; TRN: US200806%%218
Country of Publication:
United States
Language:
English