Factors affecting the survival of Chinook salmon (Oncorhynchus tshawytscha) embryos in upper and middle Columbia River watersheds, Washington State, USA

A greater understanding of environmental effects on salmon survival during incubation can aid in prediction and facilitate population modeling at local and regional scales. Four basin-scale studies of Chinook salmon egg-to-fry survival were conducted between 2009 and 2021in spawning in tributaries of the upper and middle Columbia River; each study population is currently supplemented or have a recent history of supplementation, and most listed under the U.S. Endangered Species Act. Together, these studies provided a unique opportunity to assess factors influential to egg-to-fry survival, such as fine sediment infiltration and substrate scour, in the context of differences in survival among rivers and study years. We detected a 16.8% decrease in the odds of survival for every 1-cm increase in substrate scour, a 1.0% decrease in the survival odds with each one-unit change in the percentage of accumulated fines, distinct differences in survival within and among rivers (from 30.5% to 82.5%)..., , , # Factors affecting the survival of Chinook salmon (*Oncorhynchus tshawytscha*) embryos in upper and middle Columbia River watersheds, Washington State, USA

[https://doi.org/10.5061/dryad.wm37pvmx4](https://doi.org/10.5061/dryad.wm37pvmx4)

## Description of the data and file structure

We measured egg-to-fry survival and collected associated environmental data in the Methow, Entiat, Wenatchee, and Yakima river basins in Washington State, USA from 2009 to 2022. In total, the study area represents 380 river kilometers (rkm) of Chinook salmon spawning habitat in the middle and upper Columbia River system. Our study focused on spring Chinook salmon populations, i.e., those returning in the spring of the year, but spawning in the late summer and early fall. Our overall approach was as follows: We selected study sites representing the spatial range of spawning in each river system, fertilized eggs on-site, placed them in egg boxes, and buried them in areas routinely used by naturally spawni...