The role of hatchery origin in early marine residence and survival of Interior Columbia River spring and summer Chinook salmon (Oncorhynchus tshawytscha)

Interior Columbia River spring and summer (ICRSS) Chinook salmon are listed under the Endangered Species Act and experience persistently poor survival, despite low ocean intercept rates. Intra-annual variation in marine survival among hatcheries is often as large as interannual variation. Using parentage-based tagging, we assigned ICRSS yearlings to their hatchery of origin and evaluated how size and condition at capture varied across hatcheries and whether that variation was related to marine survival. We also compared timing and size at marine entry and early ocean growth across hatchery and wild origin yearlings. We observed consistent differences in early marine residence traits among hatcheries, indicating hatchery-specific influences on performance months after release. After accounting for interannual variability, hatchery of origin explained more of the variation (~47%) in marine survival than body length or condition at capture, hatchery distance from the ocean (~16%), or the number of dams passed during migration (~14%). These findings suggest that carry-over effects associated with hatchery of origin may play a substantial role in shaping early marine survival of ICRSS Chinook Salmon.