Little is known about the effects of mud crabs population patterns on their exploitation. We used complementary
approaches (experimental, fisher-based) to investigate how small-scale variations in density, size
and sex-ratio related to the ecology of S. serrata may impact fishing practices in New Caledonia. Crabs
were measured/sexed across 9 stations in contrasted mangrove systems between 2007 and 2009. Stations
were described and classified in different kinds of mangrove forests (coastal, riverine, and estuarine); vegetation
cover was qualitatively described at station scale. Annual catch was used as an indicator of fishing pressure.
Middle-scale environmental factors (oceanic influence, vegetation cover) had significant contributions to
crab density (GLM, 84.8% of variance), crab size and sex-ratio (b30%). While small-scale natural factors
contributed significantly to population structure, current fishing levels had no impacts on mud crabs. The
observed, ecologically-driven heterogeneity of crab resource has strong social implications in the Pacific
area, where land tenure system and traditional access rights prevent most fishers from freely selecting
their harvest zones. This offers a great opportunity to encourage site-specific management of mud crab
fisheries.