Guideline for Blue Swimming Crab (Portunus pelagicus Linnaeus, 1758) stock enhancement project on seagrass bed, Sikao bay, Sikao district, Trang province

Abstract

Blue swimming crab (BSC) distribution data was studied in seagrass bed areas of Boonkong Bay (BB), Meng Island (MI), and Pakmeng Beach (PB) in Sikao District, Trang Province with the use of 218 red crab traps. The BSC were collected in September, October, and December 2011; and February, April, and May 2012. The new BSC stocks (zoea, megalopa, and crab) were released in February and March 2012. Interpolation of geographic information system (GIS) was used to analyze the distribution of BSC. The results showed that in September and October 2011, and February 2012, the BSC catch rates were lower than that of December 2011. In contrast, the BSC numbers in April and June 2012, after the release of the new stocks, increased. In BB, the BSC distributed in the middle of the bay on seagrass beds where the new stocks were released. In MI, the BSC distributed in the northeast of the area near the river channel. More middle-sized BSC (8-10 cm carapace width, CW) were found in the shallower waters than the bigger-sized BSC (> 10 cm CW). High numbers of ovigerous females were found in October and April. It was recommended that new BSC stocks should be released on seagrass beds; and the stock enhancement program could be operated all year round, except in October when the most ovigerous females were found.