Genetic Stock Identification Of Upper Cook Inlet Sockeye Salmon Harvest 2011 PDF Download

Coho salmon support important fisheries in Upper Cook Inlet. The commercial fishery harvests an average of 170,410 fish annually (2006-2015) during their homeward migration, but little is known about stock contributions. Without stock-specific harvest information, the exploitation and productivity of stocks cannot be estimated, limiting management based on sustained yield. Here we report the genetic mixed stock analysis of coho salmon harvested in the 2013-2015 test and commercial drift and set gillnet fisheries of Upper Cook Inlet. Analyses were performed using a previously reported baseline of 84 populations and 86 SNP markers. No consistent spatial or temporal patterns were observed in the stock compositions of either the southern or northern offshore test fisheries across years. However, within years, the stock compositions of the 2 test fisheries were similar. Samples from the commercial coho salmon fisheries in Upper Cook Inlet represented 77-86% of the harvest. Northern Cook Inlet coho salmon stocks (Northwest CI/Yentna, Susitna, and Knik) made up the majority of the harvest and we found several consistent temporal and spatial patterns of stock compositions within the commercial fishery across all 3 years. In the Central District drift gillnet fishery, stock proportions were fairly consistent within years until August, when proportions of Northwest CI/Yentna increased in tandem with fishery restrictions. In the Northern District set gillnet harvest, Northern stock proportions decreased and proportions of Turnagain/Northeast CI coho salmon increased after about August 12; General Subdistrict (south) harvests were dominated by Susitna and Northwest CI/Yentna coho salmon, General Subdistrict (north) harvests were dominated by Knik, and Eastern Subdistrict harvests were dominated by Turnagain/Northeast CI coho salmon. These and future Cook Inlet coho salmon commercial stock composition estimates will aid in the development of brood tables, provide for development of coho salmon escapement goals using spawner-recruit analysis, and provide data for annual run forecasts.