Landscape Models to Understand Steelhead (Oncorhynchus mykiss) Distribution and Help Prioritize Barrier Removals in the Willamette Basin, Oregon

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 61; no. 6; p. 999
• Main Authors: Steel, EAshley, Feist, Blake E, Jensen, David W, Pess, George R, Sheer, Mindi B, Brauner, Jody B, Bilby, Robert E
• Format: Journal Article
• Language: English
• Published: 01.06.2004
• ISSN: 0706-652X

Relationships between landscape characteristics (geology, land use, and climate) and the distribution of steelhead redds in four watersheds of the Willamette River basin, OR, were studied using linear mixed models. The best model results were obtained using alluvium, hillslope <6%, landslide-derived geology, young forest presence, shrub vegetation, agricultural land use, and mafic volcanic geology parameters. This approach allows temporal correlations between annual redd counts at a site while extracting relative redd density patterns across sites. The model was applied to predict redd density upstream from 111 likely migration barriers, as a way to identify high-priority barriers that might have been overlooked using only stream length or mean predicted fish benefits. Barriers that otherwise appeared similar were clearly differentiated in this way. The models are useful for improving decision-making for anadromous salmonid management.