Impact of tourism-related fishing on Tridacna maxima (Mollusca, Bivalvia) stocks in Bora-Bora lagoon (French Polynesia)

Abstract

A survey of small giant clams ('Tridacna maxima), which are subject to human predation, was carried out on the resort island of Bora-Bora in French Polynesia. This paper emphasize the impact of tourism and local activities on the Tridacna populations. Daily tours to the lagoon include the tasting of small giant clams. A study of clam abundance shows that the overall reef stock is still large. However a comparative analysis of the population structure of this clam, in four locations, shows a significant decrease in the average shell size of the living populations and a reduction in the average size of shells consummed by tourists. The average size of clams consummed by tourists fell from 130 mm to 108 mm in less than one year. On the fringing reef, the environmental conditions have reduced recruitment and increased natural mortality. This natural loss of giant clams along with the increasing human predation is decimating the standing stock of this area.