Monitoring of Downstream Salmon and Steelhead at Federal Hydroelectric Facilities, 2004-2005 Annual Report.
- Pacific States Marine Fisheries Commission, Portland, OR
The 2004 river flows were near or below the historical average for each month of the fish passage season (Mar-Oct) at John Day and Bonneville. These flow levels provided average migration conditions for juvenile salmonids, comparable to 2003. The number of fish handled at John Day increased from 166,209 in 2003 to 412,797 in 2004. This dramatic increase is due entirely to an increased sample rate to get fish for researchers, from an average of 8.5% last year to 18.5% this year. In the spring, 83% of fish sampled were for research, and in the fall, 92% were for research. Unusually small subyearling Chinook, on average 10 millimeters shorter than last year, made meeting the 110 mm fork length or 13 gram requirement difficult. Consequently, we had to sample even more fish to get the number required by researchers. Passage timing at John Day was similar to previous years, with the 10% and 90% dates within a week of last year for all species. Descaling was lower than last year for all species except sockeye and below the historical average for all species. At 5.4%, sockeye descaling was 2% higher than any other species. Mortality, while up from last year for all species and higher than the historical average for all species except sockeye, continued to be low, below 1% for all species. The number of fish sampled at Bonneville was five and one half times the number sampled last year, from 80,687 to 444,580. Like John Day, this increase resulted from research fish collections. Passage timing at Bonneville was early for spring migrants, with record early 10%, 50%, and 90% dates for yearling Chinook, unclipped steelhead, and coho. Clipped steelhead also passed Bonneville earlier than normal, with record early 50% and 90% dates and only missing the 10% date by two days. Sockeye were the exception this year with the 10% date only a couple of days different than the 50% date for three previous years and the latest 90% date of any year, except of 2001. The middle 80% of the yearling Chinook and unclipped steelhead runs took longer to pass Bonneville than any previous year, at 44 and 45 days, respectively. For subyearling Chinook, the middle 80% of the fish passed during the last three weeks of June and the first week of July, taking 35 days to pass the project, the same as last year. Descaling for all species was slightly higher than the average of the last five years. Compared to last year, descaling varied by species, increasing for yearling Chinook, coho, and sockeye and lower for subyearling Chinook and steelhead. Since sampling began in the juvenile monitoring facility, descaling has been quite consistent, staying below 3.6% for yearling and subyearling Chinook, unclipped steelhead and coho, and above 4.7% for clipped steelhead and sockeye. Mortality was slightly higher than last year and the historical average for yearling and subyearling Chinook and steelhead. Coho and sockeye mortality was lower than last year and the historical average. Mortality for all species was below 1%. Powerhouse 2 operational priority and research results showing higher survival of fish passing through the PH1 turbines rather than through the bypass system resulted in a complete disuse of the PH1 bypass system. Consequently, we removed the historic PH1 data from this report and refer readers to any prior report for information regarding first powerhouse fish sampling.
- Research Organization:
- United States. Bonneville Power Administration. Division of Fish and Wildlife.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- 00003992
- OSTI ID:
- 861481
- Report Number(s):
- DOE/BP-00003992-6; R&D Project: 198712700; TRN: US200601%%870
- Country of Publication:
- United States
- Language:
- English
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