Evaluate Status of Pacific Lamprey in the Clearwater River Drainage, Idaho: Annual Report 2001.
Recent decline of Pacific lamprey Lampetra tridentata adult migrants to the Snake River drainage has focused attention on the species. Adult Pacific lamprey counted passing Ice Harbor Dam fishway averaged 18,158 during 1962-69 and 361 during 1993-2000. Human resource manipulations in the Snake River and Clearwater River drainages have altered ecosystem habitat in the last 120 years, likely impacting the productive potential of Pacific lamprey habitat. Timber harvest, stream impoundment, road construction, grazing, mining, and community development have dominated habitat alteration in the Clearwater River system and Snake River corridor. Hydroelectric projects in the Snake River corridor impact juvenile/larval Pacific lamprey outmigrants and returning adults. Juvenile and larval lamprey outmigrants potentially pass through turbines, turbine bypass/collection systems, and over spillway structures at the four lower Snake River hydroelectric dams. Clearwater River drainage hydroelectric facilities have impacted Pacific lamprey populations to an unknown degree. The Pacific Power and Light Dam on the Clearwater River in Lewiston, Idaho, restricted chinook salmon Oncorhynchus tshawytscha passage in the 1927-1940 period, altering the migration route of outmigrating Pacific lamprey juveniles/larvae and upstream adult migrants (1927-1972). Dworshak Dam, completed in 1972, eliminated Pacific lamprey spawning and rearing in the North Fork Clearwater River drainage. Construction of the Harpster hydroelectric dam on the South Fork of the Clearwater River resulted in obstructed fish passage 1949-1963. Through Bonneville Power Administration support, the Idaho Department of Fish and Game continued investigation into the status of Pacific lamprey populations in Idaho's Clearwater River drainage in 2001. Trapping, electrofishing, and spawning ground redd surveys were used to determine Pacific lamprey distribution, life history strategies, and habitat requirements in the South Fork Clearwater River drainage. Forty-three sites in Red River, South Fork Clearwater River, and their tributaries were electrofished in 2001. Sampling yielded a total of 442 juvenile/larval Pacific lamprey. Findings indicate Pacific lamprey juveniles/larvae are not numerous or widely distributed. Pacific lamprey distribution in the South Fork of the Clearwater River drainage was confined to lower reaches of Red River and the South Fork Clearwater River.
- Research Organization:
- Bonneville Power Administration, Portland, OR (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- 00004039
- OSTI ID:
- 834372
- Report Number(s):
- DOE/BP-00004039-1; TRN: US200516%%1331
- Resource Relation:
- Other Information: PBD: 31 Dec 2002
- Country of Publication:
- United States
- Language:
- English
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