Please direct any questions to: Sara Miller (sara.miller@alaska.gov) or Richard Brenner (richard.brenner@alaska.gov).
Last updated: December 2020
The current Coghill Lake sockeye salmon SEG of 20-60,000 was adopted in 2012 after analyses that included comparisons of yield from the Ricker and Beverton-Holt models (Fair et al. 2011). In their analysis, the authors noted the absence of a clear trend in empirical estimates of yield (recruits minus brood-year spawners) across a wide range of spawning escapements. In establishing that goal in 2012 it was determined that broadening the SEG range (from the previous range of 20,000–40,000 spawners to a new range of 20,000–60,000 spawners) would allow for greater flexibility by fisheries managers without substantially risking a decrease in yields. It has been suggested that the productivity of Coghill Lake sockeye salmon might be influenced by abiotic factors that include a short ice-free period, cold temperatures, high inorganic turbidity, and meromictic characteristics that can also be disrupted by unpredictable stochastic processes (Edmundson et al. 1992, 1997). However, there was also some evidence of density-dependent effects at high levels of spawning escapement, which resulted in depleted zooplankton abundances for rearing juvenile sockeye salmon (Edmundson et al. 1997; Koenings and Kyle 1997). This influenced the team’s determination to set the upper end of the goal lower than would have been set based on spawner recruit relationship so as to not deplete juvenile forage base. For this escapement goal review, we updated escapement and return data through 2019 (brood years 1962–2014 used) and reanalyzed the Ricker spawner-recruitment relationship in a Bayesian framework (Fleischman and Reimer 2017, Fleischman et al. 2013, and Staton et al. 2016).
References: Joy, P. J., S. B. Haught, R. E. Brenner, S. Miller, J. W. Erickson, J. W. Savereide, and T. R. McKinley. 2021. Escapement goal review of Copper and Bering Rivers and Prince William Sound Pacific salmon stocks, 2020. Alaska Department of Fish and Game, Fishery Manuscript No. 21-02, Anchorage.