Skeena Test Fishery DNA (Sockeye)

The Tyee gill-net test fishery at the mouth of the Skeena River provides daily estimates of the number of sockeye entering (escaping) into the Skeena River each year from mid-June through August. The annual escapement is comprised of numerous sockeye sub-stocks each with its own entry timing (early, mid, late etc). A key component of Skeena sockeye management is estimating annual abundance and harvest/exploitation rates on sub-stocks so that fisheries can be managed with consideration for sub-stock structure rather than just simple aggregate-stock abundance. Currently, estimating catch and escapement for each stock is very difficult as visual escapement assessments are of variable quality and estimates of the catch by stock in various fisheries are not complete. An alternative strategy is to sample (proportionate to abundance) sockeye captured at the test fishing site and determine their stock of origin using microsatelite DNA stock identification techniques (Beacham et al, 2014). Given escapement counts of known accuracy for several Skeena tributary systems, and known proportions of these stocks in the escapement samples from Tyee, allows estimation of escapement to each specific sockeye stock within the Skeena River drainage. As well, stock composition estimates from the Tyee test fishery allow for stock-specific run-reconstruction back through mixed-stock marine fisheries in the Canada and S.S.E Alaskan PSC Northern Boundary Area approach waters. These analyses provide reconstructed run-timing distributions, catch estimates, and harvest rates by sub-stock which are vital to understanding migration routes, timing, and impacts by specific fisheries. To date, sockeye DNA analysis for the Tyee test fishery includes the years 2000-2017…continuation of this program through 2018 will continue to improve our understanding of migration and abundance dynamics of Skeena River sockeye sub-stocks.