Hatchery‐Origin Stray Rates and Total Run Characteristics for Pink Salmon and Chum Salmon Returning to Prince William Sound, Alaska, in 2013–2015

Pacific salmon hatcheries support important commercial fisheries for Pink Salmon Oncorhynchus gorbuscha and Chum O. keta in Prince William Sound (PWS), Alaska. State policy mandates that hatchery-produced fish must not negatively impact natural populations, which can occur during mixed via ecological genetic interactions. Therefore, we quantified the spatial temporal overlap of natural- hatchery-origin (1) as they migrated into PWS (2) spawning streams. Intensive sampling 2013–2015, combined with ancillary agency harvest hatchery composition data, also allowed us to estimate hatchery, natural, total run sizes. Estimated annual proportions (SE parentheses) preharvest ranged from 0.55 (0.01) 0.86 (0.03) 0.51 0.73 (0.02) Salmon. Proportions across all sampled streams were much lower, ranging 0.05 0.15 (0.07) 0.03 0.09 In both species, relatively high instream tended be geographically localized, while many exhibited low proportions. The estimated runs 50–142 million 2.3–5.4 Commercial harvested 94–99% 27–50% natural-origin Salmon, 17–20% Despite very rates on fish, an 0.8–4.5 30,000–90,000 strayed Our findings provide context further research relative productivity hatchery- streams, density-dependent survival, improvements fidelity release sites, influence production escapement management policy, refinements precision PWS.