EVALUATE STATUS OF PACIFIC LAMPREY IN THE CLEARWATER RIVER AND SALMON RIVER DRAINAGES, IDAHO
Annual Report 2006
Citation
Hyatt, Matthew W., Claire, Christopher, Cochnauer, Tim. 2006. EVALUATE STATUS OF PACIFIC LAMPREY IN THE CLEARWATER RIVER AND SALMON RIVER DRAINAGES, IDAHO Annual Report 2006. Idaho Department of Fish and Game. Prepared for: U.S. Department of Energy Bonneville Power Administration.
Summary
Pacific lamprey Lampetra tridentata is a native Snake River subbasin anadromous fish species occupying a unique ecological niche. Recent decline of Pacific lamprey adult migrants to the Snake River subbasin has contributed to focused attention on the species. Pacific lamprey adults counted passing Ice Harbor Dam fishway (first hydroelectric facility on Snake River) averaged 18,000 during 1962-1969 and about 600 during 1993-2006. Human manipulations of natural resource in the Snake, Clearwater, and Salmon river drainages have altered habitat characteristics of ecosystems in these basins in the last 120 years, impacting the productive potential of Pacific lamprey habitat. Timber harvest, stream impoundment, road construction, grazing, [...]
Summary
Pacific lamprey Lampetra tridentata is a native Snake River subbasin anadromous fish
species occupying a unique ecological niche. Recent decline of Pacific lamprey adult migrants
to the Snake River subbasin has contributed to focused attention on the species. Pacific
lamprey adults counted passing Ice Harbor Dam fishway (first hydroelectric facility on Snake
River) averaged 18,000 during 1962-1969 and about 600 during 1993-2006. Human
manipulations of natural resource in the Snake, Clearwater, and Salmon river drainages have
altered habitat characteristics of ecosystems in these basins in the last 120 years, 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, Salmon, and Snake river systems in Idaho. Hydroelectric projects in the Snake
River migratory corridor impact Pacific lamprey outmigrants and returning adults. The Pacific
Power and Light Lewiston Dam on the Clearwater River at Lewiston, Idaho (1927-1972),
Dworshak Dam on the N.F. Clearwater River (1972-present), and Harpster Dam on the S.F.
Clearwater River (1910-1963), severely or completely restricted Chinook salmon Oncorhynchus
tshawytscha passage and altered or obstructed passage routes of outmigrating Pacific lamprey
ammocoetes, macropthalmia, and upstream adult migrants. Sunbeam Dam constructed on the
mainstem Salmon River immediately upstream of the Yankee Fork of the Salmon River in 1910,
obstructed salmon O. spp., summer steelhead trout O. mykiss, and Pacific lamprey to an
unknown degree until removal in 1934. Prior to 1910 the majority of Snake River basin
tributaries upstream of Hells Canyon in southeastern Oregon and southwestern Idaho were
accessible to anadromous species. In the period from 1910 to 1967 numerous Bureau of
Reclamation irrigation impoundments and private and public hydroelectric projects were
completed, and culminated with the construction of the Idaho Power Company Hells Canyon
Complex (1958-1967). These impoundments have altered Snake River flow regimes, impacted
nutrient transport, and relegated anadromous accessibility in the basin to the Snake River Hells
Canyon reaches downstream of Hells Canyon Dam and the lower Snake River.
In 2006 Idaho Department of Fish and Game continued investigations into the status of
Pacific lamprey populations in Idaho’s Clearwater and Salmon river drainages. Electroshocking
and visual habitat assessment surveys were used to determine Pacific lamprey distribution, life
history strategies, habitat requirements, and population abundance in the S.F. Clearwater River,
Red River, Lochsa River, Selway River, M.F. Clearwater River, mainstem Clearwater River,
mainstem Salmon River, Little Salmon River. M.F. Salmon River, and S.F. Salmon River
watersheds. Eight-hundred and seventy-one ammocoetes and macropthalmia were captured
through electroshocking of 136 sites in these streams and their tributaries in 2006. Findings in
2006 augment 2000-2005 surveys consistently indicating Pacific lamprey ammocoetes and
macropthalmia are not numerous or widely distributed in Idaho river basins. Pacific lamprey
distribution was confined to the lower reaches of Red River below rkm 7.5, the S.F. Clearwater
River, Lochsa River (Weir Creek to mouth), Selway River (Bear Creek to mouth), M.F.
Clearwater River, the Clearwater River, the mainstem Salmon River downstream of the N.F.
Salmon River, and the M.F. Salmon River (rkm 78.7 to mouth).