Spawning Distribution of Snake River Fall Chinook Salmon

BACKGROUND

Redd counts are used to document the spawning distribution of fall Chinook salmon (Oncorhynchus tshawytscha) in the Snake River basin upriver of Lower Granite Dam for use in status assessment, management, and research.  The first reported redd counts were from aerial searches conducted intermittently between 1959 and 1978.  In 1986, the Washington Department of Fish and Wildlife began an annual monitoring program that, in addition to the Snake River, included aerial searches of the Grande Ronde River the first year, and the Imnaha River in subsequent years.  The U. S. Fish and Wildlife Service and Idaho Power Company began contributing to this effort in 1991 by increasing the number of aerial searches conducted each year and adding underwater searches in areas of the Snake River that were too deep to be searched from the air.  The Nez Perce Tribe added aerial searches in the Clearwater River basin beginning in 1988, and the Salmon River beginning in 1992.  Currently searches are conducted cooperatively by the Nez Perce Tribe, Idaho Power Company, and U. S. Fish and Wildlife Service.

The U.S. Fish and Wildlife Service conducts redd searches using funding from BPA under Project 1998-010-03.  Aerial redd searches are conducted in the Snake River from mid-October to mid-December, and underwater searches are conducted from mid-November to mid-December.  Costs and workload associated with redd searches in the Snake River are shared with Idaho Power Company.  After the spawning season has ended, and each surveyor has proofed their data, the project lead for 1998-010-03, Aaron Garcia, compiles all redd search data collected upriver of Lower Granite Dam and presents it in an annual report.

COORDINATION

We work closely with the Nez Perce Tribe, Idaho Power Company, and Washington Department of Fish and Wildlife, to ensure needed data are collected, summarized, and disseminated.  Efforts by the U.S. Fish and Wildlife Service, Nez Perce Tribe, Idaho Power Company, to publish findings from redd searches conducted over the past decade are ongoing.

GOAL

Our goal is to provide information on the spawning distribution of Snake River fall Chinook salmon so that management actions, and the status of the population, can be evaluated.

OBJECTIVE AND RATIONALE

Objective: Determine the number of redds constructed in the Snake River above Lower Granite Dam, summarize the data along with that from all redd searches conducted above the dam, and make it available to managers and researchers.

Rationale: Fall Chinook salmon in the Snake River are listed under the Endangered Species Act as a Threatened Species.  A major recovery action involves the release of hatchery-origin fall Chinook juveniles above Lower Granite Dam annually.  Redd searches are used to monitor the affects of this action, and the population status as a whole, as per Hatchery NMFS 174 Pt.4 (Determine relative distribution and timing of hatchery and natural spawners), Hydro NMFS 107 (Assess survival of adult salmonids migrating upstream), RM&E NMFS 182 (Determine the reproductive success of hatchery fish relative to wild fish), RM&E NMFS 184 (Hatchery research, monitoring, and evaluation program), and RM&E NMFS 199 (Implement the specific research/monitoring actions outlined in Appendix H).