Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8498
Title: Shallow tidal freshwater habitats of the Columbia River: Spatial and temporal variability of fish communities and density, size, and genetic stock composition of juvenile Chinook Salmon
Author: N. K. Sather, Gary E. Johnson, David J. Teel, Adam J. Storch, J. R. Skalski, Valerie I. Cullinan
Publication Year: 2016
Journal: Transactions of the American Fisheries Society
Keywords: juvenile Chinook salmon,Columbia River Estuary,tidal freshwater

We investigated spatial and temporal variability of the fish community and density, size, and genetic stock composition of juvenile Chinook Salmon Oncorhynchus tshawytscha in shallow tidal freshwater habitats of the Columbia River. The impetus for the study was to address data gaps related to juvenile Chinook Salmon in this portion of the Columbia River to inform habitat restoration efforts. We examined fish communities, attributes of juvenile salmon life-history characteristics, and relationships to habitat conditions using beach seine data from two tidal freshwater areas, the Sandy River delta (rkm 188–202) and the “Lower River Reach” (rkm 110–141), over a 63-month period (2007−2012). We found few differences in the fish community across the two study areas. Fish community patterns were largely attributable to seasonal changes as opposed to spatial gradients and habitat types. Juvenile Chinook Salmon, the most common salmon species in our catches, were the only salmon species encountered during all seasons. Densities of Chinook Salmon differed among three distinct habitat strata (main channel, off-channel, and wetland), but fork lengths (FLs) and genetic stock composition did not. Across all habitat strata, environmental covariates (mean percent tree cover, dissolved oxygen, and mean percent emergent vegetation) were positively associated with juvenile salmon density. While comparisons of environmental metrics and salmon density helped to establish a quantitative relationship between biotic and abiotic conditions, we found juvenile salmon to occupy a range of habitats. These findings support a strategy of restoring a diversity of shallow tidal freshwater habitats to support recovery of threatened and endangered salmon populations in the Columbia River basin.

Theme: Recovery and rebuilding of marine and coastal species
Foci: Characterize the population biology of species, and develop and improve methods for predicting the status of populations.