Enhancing stocks of blue swimming crabs in Guiuan, Eastern Samar

Over time, the declining population of wild blue swimming crabs (BSC) or commonly called alimasag was mostly due to heavy and overfishing activities of local fisherfolk who depend on this resource for their livelihood.Urbanization also resulted to natural habitat loss and reduced quality of the coastal water. This declining stock of alimasag has a negative effect on the catch and income of the crab fishers. 

To abate this problem, the DA-National Fisheries Research and Development Institute (NFRDI) in collaboration with DA-Bureau of Fisheries and Aquatic Resources (BFAR)-Eastern Visayas, implemented a project to enhance the stocks of alimasag in the wild and increase crab yield. The project intends to improve the economic gain of small-scale local crab fisherfolk, by releasing hatchery-bred crablets in selected suitable habitats in the wild of Dinahic and Bucaboc Reef in Guiuan, Eastern Samar. 

DA-BFAR hatcheries developed protocols for larval and juvenile rearing to produce healthy crab juveniles which will be reseeded in  marine protected areas (MPAs). Since 2009, DA-BFAR-Guiuan Marine Fisheries and Development Center (GMFDC) released 180,525 crab juveniles to 12 MPAs in Eastern Samar, except in 2013-2015 during and after typhoon Yolanda. 

On its first year, BSC project successfully produced and released 96,234 crablets from October 2020 to November 2021, which is 64.16% of the total target of 150,000 crablets. Further, 51,337 and 44,897 crablets were harvested from the hatchery and were released in Dinahic and Bucaboc reef, respectively. 

To assess the impact of the stock enhancement, the daily catch collected every month of the crab fisherfolk was computed to determine their Catch Per Unit Effort (CPUE). There was a slight increase in the mean CPUE computed at 1.63 kg/day compared to 1.49 kg/day before the stock enhancement. 

“Stock enhancement is a good way to replenish the depleted BSC population in the wild to ensure the sustainability of the resource. However, its effect could be evident if there is a successive release of crablets every other month and is conducted in a longer period of time,” said project leader Nonita S. Cabacaba. 

Beyond the current project targets, GMFDC is also continuing hatchery production of blue swimming crab for reseeding in enhancement sites in Guiuan MPAs. (### Maria Elena M. Garces)