Author: Rich BrennerPublisher:
ISBN:
Category : Escapement (Fisheries)
Languages : en
Pages : 34
Book Description
Chilkoot Lake, located in upper Lynn Canal near the city of Haines, supports one of the largest runs of sockeye salmon (Oncorhynchus nerka) in southeast Alaska. This stock is currently managed as a sustainable escapement goal range with a lower bound of 38,000 and an upper bound of 86,000 spawners. Escapement is monitored by the Alaska Department of Fish and Game with a weir on the Chilkoot River, and stock of origin from the District 15 commercial drift gillnet fishery harvest is determined using scale pattern analysis. We used Ricker spawner-recuit models in a Bayesian framework to fit data from brood years 1976-2010. Given significant autocorrelation at lag-1, we chose an autoregressive Ricker model for this assessment. Based on model results, maximum sustainable yield would be achieved with an escapement of approximately 52,900 sockeye salmon (median of spawning abundance at maximum sustained yield), and a range of 45,000-60,000 spawners would result in a greater than 80% probability of achieving at least 90% of maximum sustainable yield. This range of escapements fits within the current escapement goal range and, given considerable uncertainty in parameter estimates, we do not recommend changes to the goal at this time. However, some large escapements since 2012 will provide contrast to the existing data once the resulting recruits can be enumerated; thus, we recommend reassessing this escapement goal prior to the Alaska Board of Fisheries meeting in 2021.