Skeena Sockeye In-river Run Reconstruction Analysis Model and Preliminary Analysis Results for 1982-2009

Note: This analysis has since been updated, and the most recent version is available here.

Summary

“The Fraser, Skeena and Nass watersheds are the three largest sockeye producing watersheds in British Columbia. Exploitation rate estimates for the Nass and Skeena Sockeye stock aggregates are estimated annually using the Northern Boundary Sockeye Run Reconstruction (NBSRR) Model (English et al. 2004b; 2005; Alexander et al. 2010). English et al. (2011) provided estimates of marine exploitation rates for each Nass and Skeena sockeye Conservation Unit (CU) using estimates of the migration timing for each CU. These analyses have not included the details on the location and timing of in-river fisheries needed to estimate harvests for the various sockeye CUs or sub-stocks within each watershed. In some years, in-river harvest account for a large portion of the Canadian harvest of sockeye returning to these rivers. Run reconstruction analyses have been used to estimate CU specific harvest rates for in-river fisheries targeting Fraser sockeye and Chinook salmon (English et al. 2007; Noble 2011). This report provides a brief outline of a Skeena Sockeye In-River (SSIR) run reconstruction model built to combine information on run timing and escapements for Skeena sockeye sub-stocks with catch estimates for each sockeye fishery within the Skeena watershed. The model is similar to those developed for the Fraser River sockeye fisheries within the Fraser watershed except that the Skeena model moves fish forward (upstream) through the fisheries and subtracts sockeye catches from estimates of the number of sockeye entering the Skeena River each day. The Fraser sockeye reconstructs the run entering the Fraser River by adding catches to daily estimates of escapement for each sub-stock.”

–Excerpt from the report