Measuring the potential influence of cooking on the carbon and nitrogen isotopic composition of spawning Chinook salmon

This study considers the effect of heat treatment (cooking) on muscle tissue from modern spawning Alaskan Chinook salmon (Oncorhynchus tshawytscha) and implications for archaeological dietary reconstructions. Here, it is demonstrated that cooking, potentially through exposure to lighter volatiles present in wood smoke, significantly alters the stable carbon (δ13C) isotopic composition of muscle tissue, though the difference may be too slight (− 0.50‰) to be incorporated into dietary mixing models. Cooking produces no significant change in nitrogen (δ15N) values. Additionally, this study identifies significant differences in stable nitrogen (δ15N) and carbon (δ13C) isotopic values between previous studies on coastal adult Chinook salmon and the spawning adult Chinook salmon from Central Alaska analyzed in this study, emphasizing the importance of employing isotopic data from local fauna in dietary reconstructions. The data presented here have implications not only for our understanding of general salmon ecology, but also for refining archaeological reconstructions of prehistoric diet in Central Alaska and other regions where smoke-preserved tissue was regularly consumed.