Chinook salmon populations in California are in decline due to the combined effects of habitat degradation, water diversions, and shifting climate regimes. Effective salmon conservation and management relies on understanding their life history diversity and ability to adapt to environmental change. Monitoring efforts and geochemical tools have provided crucial insights into modern salmon population dynamics and behavior in California, but these data were collected only after significant population declines and extirpation from a large fraction of their historic habitat.

We are addressing this critical data gap by reconstructing key life history metrics (age, growth, habitat use, migration timings, genotype) in adult salmon otoliths preserved over a 6000-year time series in archeological sites on the Feather River as well as modern spring run Chinook salmon across the Sacramento River watershed. This project aims to understand the mechanisms and

responses of salmon to changing climate regimes by analyzing microstructure, microchemistry, stable isotopes, and ancient DNA to archaeological otoliths and vertebrae. This will allow us to derive drivers of salmon resilience that allowed salmon to persist through mega droughts and landscape evolution, data that can inform future management and conservation actions in a changing climate.