|all photos USFWS|
Historically the core population of Snake River fall Chinook salmon spawned upstream of where the Hells Canyon Complex of dams (Hells Canyon, Oxbow, and Brownlee) now lies. The Hells Canyon Complex was designed to allow fish passage but the system did not work, and spawning upstream of the Hells Canyon Complex ended by the late 1960’s. By the mid 1970’s four dams (Ice Harbor, Lower Monumental, Little Goose, and Lower Granite) were in place on the lower Snake River. The lower Snake River dams allowed fish passage and currently most fall Chinook salmon spawning occurs within the 173 km free-flowing reach of the Snake River between Lower Granite and Hells Canyon dams, and the lower reaches of Snake River tributaries including the Imnaha, Salmon, Grande Ronde, and Clearwater.
The placement of dams on the Snake River required mitigation to ensure a viable population of fall Chinook salmon was maintained. The main approach was to establish a hatchery stock of Snake River fall Chinook salmon by trapping spawners at dams and rearing their offspring at hatcheries. Lyons Ferry Hatchery was constructed for this purpose and reared its first brood in 1984.
Even with mitigation efforts, by 1992 the Snake River fall Chinook salmon population was low enough to merit listing under the Endangered Species Act. Determining how to recover the population required information on wild fall Chinook salmon that did not exist. Thus, staff of the Idaho Fishery Resource Office began a long-term series of cooperative research projects to collect needed information and help managers plan and evaluate recovery efforts. Our cooperators presently include the Idaho Power Company, Nez Perce Tribe Department of Fisheries Resources Management, National Oceanographic and Atmospheric Administration Fisheries, Pacific Northwest National Laboratory, U. S. Geological Survey, University of Idaho, University of Washington, and Washington Department of Fish and Wildlife. Research projects have and continue to address: 1) the genetic characterization of wild Snake River fall Chinook salmon; 2) contemporary spawning distribution, 3) juvenile life history diversity and growth, 4) behavior of juveniles during seaward migration, 5) survival of juveniles during seaward migration, 6) the efficacy of supplementation, and 7) the efficacy of summer transportation and spill.
|all photos USFWS|
The study of mountain whitefish (Prosopium williamsoni) began in 1992 as part of the Fishery Resource Status and Trends program developed by the U.S. Fish and Wildlife Service. It was conducted under the Global Climate Change component designed to collect long-term population and environmental data for specific fish species. The area of study was Killed Creek and Crooked Fork creeks which are located in the headwaters of the Lochsa River drainage near the Idaho/Montana border. Mountain whitefish inhabit cold, low gradient streams and, in Idaho, are most often found in streams 15 meters in width or greater. Very little is known about the life history, status, and habitat requirements of mountain whitefish. Northcote and Ennis have attributed the lack of research of P. williamsoni to it being a species of less appeal to anglers. More information about the FROs contribution to research on mountain whitefish can be found here.