Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7579
Title: Habitat connectivity, complexity and quality: Predicting adult coho salmon occupancy and abundance
Author: Kara Anlauf-Dunn, E. J. Ward, M. Strickland
Publication Year: 2014
Journal: Canadian Journal of Fisheries and Aquatic Sciences
Keywords: coho salmon,habitat,occupancy,abundance,climate,threatened,

 The distribution, quality, and connectivity of in-stream habitat can influence adult salmon occupancy and abundance patterns, and alter population dynamics. In this study, we evaluated the relationships between adult coho salmon occupancy and abundance with in-stream habitat conditions, including measures of spawning gravel, habitat complexity, and juvenile rearing habitat. We used corresponding adult salmon spawning and in-stream habitat data collected within coastal Oregon watersheds as part of a long-term monitoring program. We modeled two processes as a function of habitat characteristics; the number of coho salmon when they were present, and the occupancy probabilities of coho salmon. The results from both sub-models were then combined into an estimate of total abundance at each site. Adult coho salmon occupancy was best predicted by the capacity of the habitat to support parr during the winter, complex pools, percent bedrock, and site distance from the ocean. Increases in adult coho counts at sites were also influenced by the site distance from the ocean, and there is evidence that both percent gravel and complex pools may also be good predictors. Combined, our results indicate the spatial distribution and proximity of spawning and rearing habitats may maximize productivity for coho salmon in coastal Oregon watersheds.