Fishing further inland? The role of the transition to agriculture on fishing practices in the Soconusco region, Mexico

In the Soconusco region of Mexico, the abundance of larger-bodied, carnivorous fish decreased relative to smaller-bodied, omnivorous/herbivorous fish between the terminal Late Archaic (4700–4000 BP [2700–2000 BCE]) and late Early Formative (3300–3200 BP [1300–1200 BCE]). The exact reason is unknown, occurring during a time of change when plant-based food production became a larger proportion of the diet and settlement patterns were shifting. Here, we address whether the same diversity of fish harvested during the terminal Late Archaic persisted into the Formative Period and if it reflects a change in where fish were being harvested. Using seven previously identified and published zooarchaeological assemblages dating to between the Middle Archaic and Middle Formative periods, we analyzed changes in diversity (NISP versus NTAXA, evenness, and richness) and habitat exploitation (nestedness and proportion of aquatic environment). We find differences in taxonomic diversity, changes in where fish were harvested along the coast, and the degree of exploitation intensity. Finally, we conclude the Chantuto society may have shifted their focus from marine to more freshwater species in conjunction with early low-level food production and agricultural production. We suggest the shift in focus during the late Early Formative and Middle Formative to estuarine–riverine environments may have occurred in conjunction with agricultural intensification.