| Abstract/Description or Keywords |
We used reported commercial catch data and historical information to estimate the abundance of Skeena River Chum Salmon Oncorhynchus keta during the early rise (1916–1919) in the commercial fishery to provide historical perspective for recovery plans. We applied a Bayesian analysis to address the uncertainties associated with the estimation process. Based on the historical catch of 204,000 in 1919 and an estimated harvest rate of 0.32–0.58, the estimated return of Skeena Chum Salmon ranged from 355,000 to 619,000, with the most probable single estimate being 431,000. The estimated return of Chum Salmon based on the 1916–1919 geometric mean catch of 154,000 ranged from 268,000 to 471,000, with the most probable single estimate being 325,000. Our posterior modal historical estimates are 8–11 times larger than the estimates for the contemporary period 1982–2010 and 39–52 times larger than those for the most recent period of 2007–2010. Intense harvest pressure is the single most probable factor explaining the sustained decline in Chum Salmon abundance, but other interactive factors, notably natural variations in survival, the loss of spawning and rearing habitat, and poor data quality, also are important considerations. Nonetheless, the Skeena catchment is largely pristine today, and our robust estimates of historical abundance should be of value to contemporary management and conservation agencies for the rebuilding of such severely diminished populations. |
