Acoustic telemetry yields stock membership clues for Coho Salmon harvested in coastal fisheries

Abstract Objective Estimates of Pacific salmon Oncorhynchus spp. stock composition in coastal fishery harvests are needed to balance fishing opportunities against conservation. Catch partitioning in some small-scale fisheries can be hindered by insufficient resolution of modern stock classification tools (e.g., genetic stock identification). Methods We used acoustic telemetry to investigate the stock composition of commercial landings in the Norton Sound district of Alaska by mimicking local fisheries to capture and tag 578 Coho Salmon O. kisutch in the contiguous Shaktoolik and Unalakleet commercial subdistricts over two seasons. Result In total, 341 individuals that were last detected in demarcated spawning areas were assigned to a stock of origin based on putative natal site fidelity. Sex, location of capture, and timing of capture were predictors of stock membership. Models that were fitted to commercial harvest data from the project years (2020 and 2021) estimated that 32.9% of the Shaktoolik subdistrict catch was Shaktoolik stock, 51.5% was Unalakleet stock, and the remainder consisted of other transitory stocks. Conversely, 86.7% of landed Coho Salmon in the Unalakleet subdistrict were Unalakleet stock, whereas the Shaktoolik stock and transitory stocks made up less than 10%, respectively. Conclusion These findings suggest that coastal salmon fisheries in Norton Sound have access to a variable mixture of stocks whose unique characteristics can be leveraged to examine the effects of directed harvest effort on stock health and diversity.