Distribution of blue swimming crab (Portunus pelagicus Linnaeus, 1758) in Trang Province

The fishery of the blue swimming crab (Portunus pelagicus Linnaeus, 1758) is very important to the economy of small-scale fishermen. Greater knowledge about its distribution could lead to more efficient management. This study was conducted in Trang Province from October 2006 to August 2007 using collapsible crab traps. To reveal the spatial distribution of the species, we analyzed the data using geostatistical methods. The standard interpolate procedure was applied to model the crab distribution. There were clear spatial distribution differences among the small crabs, large crabs and ovigerous females in study area. The mapping showed that small crabs (carapace width < 10 cm) were most often found inshoreand associated with seagrass beds, especially between April and September, whereas large crabs (carapace width > 10 cm) were farther offshore. Ovigerous females peaked in abundance during 2 periods: March – April and August – September. This information can be used to support decision making concerning the designation of fishing zones and the optimization of the blue swimming crab fishery in the study area.