Movements and Distribution of Northern Squawfish Downstream of Lower Snake River Dams Relative to the Migration of Juvenile Salmonids, 1992-1993 Completion Report.
- University of Idaho, Idaho Cooperative Fish and Wildlife Research Unit, Moscow, ID
Northern squawfish Ptychocheilus oregonensis movements were monitored downstream of two lower Snake River dams during the juvenile salmonid migrations of 1992 and 1993. During a high flow year in 1993, the abundance of squawfish in the tailrace of Lower Granite Dam peaked in July, after the majority of juveniles had moved past Lower Granite Dam, and peak abundance was inversely related to river discharge. Few squawfish moved into the tailrace of Ice Harbor Dam in 1993 because of the extended period of spill. Distributions of squawfish in the tailrace of Lower Granite Dam varied between and within years and shifted in response to changing prey densities, flow patterns, water temperature, and diel cycles, but fish consistently used low velocity habitats. Data from Ice Harbor Dam is less extensive, but squawfish distributions there appeared to be affected by changing flow patterns and fish used low velocity habitats. The changes in distribution and abundance of squawfish in tailrace areas are evidence that predation on seaward migrating salmonids depends on the timing of migration and size and timing of runoff. Juvenile salmonids migrating in the spring and early summer will probably be less affected by squawfish predation in tailrace areas than salmon that migrate later in the summer.
- Research Organization:
- Bonneville Power Administration, Portland, OR (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- 1988BP91964
- OSTI ID:
- 266881
- Report Number(s):
- DOE/BP-91964-5; R&D Project: 198200300; ON: DE96012892; TRN: 96:004419
- Resource Relation:
- Other Information: PBD: Mar 1996; Related Information: Paper document orginially marked incorrectly as DOE/BP-63584-11, but the real number is DOE/BP-91964-5.
- Country of Publication:
- United States
- Language:
- English
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