The main goal of this study was to gather information about historical changes in water temperature and species composition, in order to identify variables that will enable us to predict changes in water temperatures and species abundances in California caused by global climate change. Our primary objectives were to (1) review the existing published and unpublished data sets to refine our understanding of trends in sea surface temperature in central California; (2) review fish and climate data sets to determine if we could identify how species abundances changed relative to changes in water temperatures and basin-scale environmental indices; and (3) identify recent changes in species abundances in central California that are related to water temperatures.