Comparison of mangrove oyster shells lengths harvested in Cuba during the pre-Columbian era and the present day

The Mangrove oyster [Crassostrea rhizophorae (Guilding, 1828)] was intensely harvested in the pre-Columbian era by an aboriginal group of hunters and gatherers known as the Ciboney who lived exclusively in Western Cuba. During a comprehensive study of mangrove oyster fishing areas it was of interest to compare the population characteristics under contemporary exploitation with those in pre-Columbian times and for that purpose two samples were used: one from a Ciboney midden in an archeological site 3 km inland from the Jaruco River mouth and another from a commercially exploited population in the ecologically similar Tacajó River. The samples were studied with a ‘shell classifier’ of original design resulting in a mean length of 51.8 ± 2.5 mm for the midden shells and 51.0 ± 3.1 mm for the contemporary sample. Both values were not statistically different for any P > 0.10 meaning that the two populations they came from had similar characteristics. It was also concluded that the Ciboney's manual harvesting exerted less negative anthropogenic pressure on the mangrove oysters’ populations than the contemporary commercial practices based on the use of metal instruments to gather the oysters along with the mangrove aerial roots they are attached to. This latter conclusion is based on the fact that oyster shells 41–80 mm long from the midden are 12% more abundant than in the modern sample, in spite of 500 years of weathering.