Chinook Salmon Escapement Estimation to the Skeena River Using Genetic Techniques

The Skeena River is host to the second largest aggregate of Chinook salmon in British Columbia. While the aggregate is a PSC escapement indicator stock, there are no biologically based escapement goals for this population. This project provides an annual escapement estimate for the aggregate as well as for the large component stocks. The estimate produced is comparable with the historic estimates produced using an estimate of variance. The Tyee Test fishery, which has been conducted since 1955, provides data such as age information that is matched to the genetic information. The combination of stock specific escapements with age composition forms the basis for escapement goals and benchmarks.
The Kitsumkalum River hosts one of the major Chinook populations in the Skeena watershed, and is a PSC exploitation rate indicator stock. The mark-recapture estimate produced in in a separate project forms the cornerstone for the expansions of the stock compositions observed at the Tyee Test fishery.
The project consists of genetic analyses of samples from Chinook salmon caught at the Tyee Test fishery, and escapement data from the Kitsumkalum mark-recapture program. Chinook salmon scale samples will be collected from the Tyee Test Fishery and the DNA from the samples will be compared against genetic baselines from Skeena Chinook salmon populations. The proportion identified as Kitsumkalum Chinook will be expanded to generate escapement estimates for the Skeena River aggregate using the mark-recapture estimate of escapement for the Kitsumkalum population. The project builds on the results from the 2009 to 2014 Sentinel Stocks Program (SSP) projects that provided annual estimates, as well as the results produced by the Retrospective Projects with the funding received in 2011 and 2012. There are currently estimates for 31 years in the time series (1984 to 2014). The program has been funded by the Northern Endowment Fund since 2015.