A mark-recapture project would be conducted to estimate escapement and would involve capturing and marking live fish as they migrate to the spawning grounds and recovering carcasses. The Coded Wire Tag (CWT) smolt group is required to continue representation of Lower Shuswap River (and Fraser River Summer 0.3) Chinook in subsequent fisheries and escapement. This project includes capture of brood stock, rearing of like-timed and like-sized 0+ smolts, and purchase and application of 100,000 CWTs to those hatchery smolts, as part of the overall release group.
The data acquired from the application of CWT’s aids in the computation of the exploitation rate data that are used for several purposes, including estimation of maturation rates, reconstruction of production for stock-recruitment analysis, monitoring Individual Stock Based Management (ISBM) fishery obligations (specified in the 2009 Agreement), development of agency forecasts for the PSC Chinook model calibration, and providing an independent verification of the PSC Chinook model representation of fisheries, stock dynamics, and stock distribution among fisheries and escapement.
In particular, the Fraser River Summer-run Age 0.3 Chinook Stock (South Thompson aggregate including the Lower Shuswap) is one of the largest contributors to Southeast Alaska (SEAK) and Northern BC (NBC) fisheries, as well as recreational and First Nations harvests in the ocean and freshwater. Because of this fact, high quality, accurate escapement estimates are required to accurately forecast the NBC and SEAK AABM abundance indices. Recently, the CTC and PSC have expressed concerns about the performance of the Chinook Model, especially for northern fisheries, and this project will ensure availability of quality escapement and maturation rate data for one of the largest stocks.