Fall Chinook Stock Composition IV

The objective of this project was to identify stock composition and run timing of summer and fall Chinook salmon passing Bonneville Dam. Included in this study was an evaluation of the cut-off date that designates the start of the summer run of Chinook salmon. A total of 1163 samples collected at Bonneville Dam from June 1 to October 20, 2005 were genotyped with 13 microsatellite loci. A genetic baseline of 55 populations was utilized to complete genetic stock identification of unknown origin samples from Bonneville Dam. Of the 450 samples collected as summer run Chinook (June 16 to July 19), the majority (90.2%) were from the mid/upper Columbia River reporting unit (Hanford Reach/Methow River) with very minor contribution from Snake River (1.6%) and Klickitat River (1.4%) reporting units. Of the 515 fall run samples collected from September 9 to October 20, a much larger proportion of the mixture was composed of Snake River (21.7%), Klickitat River (3.7%), and Deschutes River (3.0%) reporting units relative to the summer collection. However, the fall mixture was still dominated in composition by the mid/upper Columbia River reporting unit (70.1%). This study demonstrated the utility of GSI methods for evaluating stock composition of Chinook salmon mixtures from Bonneville Dam and potential for managing fisheries with this additional information.

This proposal seeks to utilize baseline genetic data for GSI of unknown origin Chinook salmon from Bonneville Dam and mixed stock fisheries. Understanding the proportion of specific stocks within a fishery is critical to understand stock-specific mortality rates and harvest levels. In addition, harvest opportunities can be identified if genetic data confirms the absence of non-target stocks in a planned fishery. Testing Genetic Stock Identification techniques at this time will allow for real-time management (48-72 information) of fisheries in future years.
Project staffing is distributed as follows: Shawn Narum, (genetics, data analysis, reporting, 3 months), Jeff Stephenson (genetic data collections and analysis, 2 months), lab technician (DNA extraction and genetic data collection, 6 months).