Marine fish population sizes may vary over periods of months to decades in response to natural ocean cycles, which inevitably favor some species over others. Superimposed on these natural cycles are a host of man-made stressors, such as fishing and anthropogenic climate change, which may also cause further swings in fish population sizes. This project seeks to reconstruct patterns of fish abundances in the Santa Barbara Channel over a 2,000 year period predating modern human activity to tease apart the processes most affecting fish populations currently. The raw material for this reconstruction will be layered sequences of otoliths (ear-bone-like structures) in sediment cores extracted from the seafloor below the Santa Barbara Basin. The shape, size, and elemental composition of these otoliths, along with assumptions about their deposition rates, will be used to estimate fish biomasses over time and in relation to ocean climate. Data collected from this study will be shared with fishery managers and policy makers. Researchers will also produce an online key for identifying the region’s marine fishes from their otoliths.