This project, which has been running since 2002, describes the stock composition of chum and Chinook salmon returning up the Yukon River to Canada. It estimates what proportion of these fish return to each of the genetically-identifiable stocks (by natal stream). Though monitoring of the aggregate is practical and the basis for much of the management, it is equally important to understand status and trends at the population level. Given the size of the Yukon River watershed and the climatic variation found within it, salmon populations within the watershed may experience significant differences.
The effectiveness of this project is closely tied to the development and refinement of the genetic baseline and the number of samples obtained from the Eagle Sonar Site. As more genetic samples are collected and analyzed from Eagle, the sampling error decreases and the estimates of stock compositions are made more reliable. There are two principal uses of the GSI information collected. The first is in assessing how genetic information compares to traditional stock assessment information. Fishery managers often rely on index stocks to understand both status and trends in particular populations or stocks, and for Yukon River salmon, many terminal escapement assessments are carried out each year (e.g., using sonars, aerial surveys, and counting weirs), which can be costly and logistically challenging, and typically assess only one population at a time. When combined with sonar counts, genetic proportion estimates can be expanded to provide escapement estimates for particular populations. The second is that the information in aggregate can be used to estimate the productivity of each population of Canadian-origin salmon. This type of information is critical to local management planning and is of great interest to First Nation governments and communities as they seek greater information on the fish that return to their traditional territory. Projects focused on stock restoration also need to understand which stocks are currently highly productive and which are not.