Evaluation of the Skagit hatchery spring Chinook program after a change in hatchery production strategy.

In 2012, as a result of

WDFW’s reduced financial support for the Marblemount hatchery spring Chinook program, production strategy was changed from both sub-yearlings (~250,000) and yearlings (~150,000) to exclusive production of sub-yearlings (~250,000). USIT funded increased production of subyearlings (additional ~337,000, to total ~587,000), hoping to mitigate for the loss in adult returns from this modified production strategy. The fish from this program comprise a DIT (double index tag) group and includes those identifiable by a combined adipose mark and CWT and those with CWT only.

Our evaluation of the performance of the exclusive sub-yearling production strategy will be the first conducted since the change in production strategy. This critical assessment will inform if the change in production strategy has effectively maintained the overall productivity of the Skagit Spring Chinook hatchery program. The exclusive sub-yearling production strategy may result in substantive differences in survival, migratory patterns, and age structure that may not maintain harvest opportunities from hatchery production in the Skagit. This would have direct implications on both the tribal harvest opportunity in the Skagit and on the impacts from all fisheries on both hatchery and wild Skagit spring Chinook.