Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8338
Title: Historic potential spawning abundance estimates for Columbia River Basin salmon and steelhead in areas above Bonneville Dam
Author: G. R. Pess, Bill McMillan, T. J. Beechie, H. Imaki
Journal: North American Journal of Fisheries Management
Keywords: historical ecology,Columbia River Basin,spawning,habitat capacity

 Estimates of historical capacity and abundance levels are critical for salmon population recovery planning. We developed a historic salmon spawning capacity estimate for the Columbia River basin using historic habitat information on the proportion of spawning habitat and salmon spawning nest (redd) size from several watersheds and portions of the main stem Columbia. We then used Monte Carlo simulations to gain a distribution of potential capacity by species and watershed. We found that  total potential spawners in the Columbia River basin for the watersheds and main stem Columbia River is approximately 124.0M (S.D., 48.6M) assuming no space between redds and 41.3M (S.D., 16.2M) assuming redd spacing 3 times larger than the average redd for a given species. We also found that our estimates suggest that the main stem Columbia and Yakima River had greatest capacity for salmonids and that Coho salmon spawning capacity was as large as Chinook salmon capacity. Our gravel based estimates are typically ~71% to 88% greater than what was counted in the early to mid-1900s with dams and weirs. In addition our overall capacity estimates are larger than previous abundance estimates for the Columbia River basin. However our capacity estimates are comparable to other historic estimates for similar sized watersheds across the Pacific Rim.

Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Characterize the interaction of human use and habitat distribution, quantity and quality.
Develop effective and efficient habitat restoration and conservation techniques.