Biophysical Factors Associated with the Marine Survival of Auke Creek, Alaska, Coho Salmon

Abstract

Correlation analyses and stepwise regression models were run to examine relationships between the marine survival of Auke Creek coho salmon Oncorhynchus kisutch and a number of physical and biological covariates: Local sea surface temperature, local precipitation, local hatchery releases of pink salmon O. gorbuscha and chum salmon O. keta, regional and state coho and pink salmon catches, and smolt survival of three other regional coho salmon stocks. Auke Creek jack return rates and adult marine survival covaried, indicating that a significant amount of the variation in marine survival is due to conditions encountered in the first 4 to 5 months of marine life. Sea surface temperature was not significantly correlated with adult survival but was significantly associated with jack return rates. Precipitation had no relationship with marine survival. The number of locally released hatchery pink and chum salmon had the strongest correlation with marine survival (r = 0.71). Marine survival trends of coho salmon stocks within 64 km of Auke Creek closely followed Auke Creek marine survival, indicating that the factors affecting the marine survival of coho salmon are similar in localized regions of northern Southeast Alaska. Regional similarities in marine survival with Auke Creek coho salmon also extend to the larger Southeast Alaska region with respect to the analysis of commercial coho salmon catch. The specific mechanisms were not identified, but these results indicate that biological covariates were more associated with Auke Creek coho salmon marine survival than were physical covariates.