Comparing zooarchaeological data for Native American, Spanish, and British occupations with modern fisheries data from St. Johns County, Florida (USA) shows differences in the use of marine resources from 1450 B.C. through A.D. 2000. Changes in biomass contribution, diversity, types of fishes used, and trophic levels of sharks, rays, and bony fishes suggest that the pattern described as “fishing down marine food webs” (Pauly et al. 1998) may have been present in the St. Johns County area as early as the eighteenth century. A change in the size and growth habits of Atlantic croaker (Sciaenidae: Micropogonias undulatus) occurred early in this sequence, indicating an impact on this specific fish. However, overharvesting of fishes is not the only explanation for these observations. Climate and cultural changes are additional explanations for the patterns observed that should receive closer attention. Exploring these alternative explanations is made possible by a zooarchaeological record that permits us to study fishing habits and fish behavior before large-scale industrial fishing began.