Increasing alimasag production highlighted in DA-BAR webinar

“The BSC [blue swimming crab], or locally known as alimasag, is considered a delicacy because of its firm texture and sweet taste. Due to its economic importance and long socio-cultural value, management and conservation of the resource must be adopted to strengthen the livelihood of small-scale crab fishers and to uphold the sustainability of the resource,” shared Nonita S. Cabacaba during the DA-BAR online seminar held on 20 July 2023 via Streamyard and Facebook Live.

Cabacaba, Chief Science Research Specialist of DA-National Fisheries Research and Development Center-Marine Fisheries Research Development Center (NFRDI-MFRDC), is the project leader of the DA-BAR-funded project that aimed to enhance the population of BSC in the wild through the release of hatchery-bred crablets in Guiuan, Eastern Samar. 

One of the problems in the hatchery is the lack of available quality broodstock for larviculture, where in wild berried crabs are oftentimes difficult to source from local fishermen or buying station.  Also, with limited information on the feeding requirements, type of environment, culture systems, and water quality, mass mortality during larval stages often happens. 

Stock enhancement is one conservation measure used to address the depleting BSC population in the wild and ensure the sustainability of the resource. The crab juveniles are produced using the methods modified from the pioneering technologies of mangrove crab hatchery rearing by Southeast Asian Fisheries Development Center-Aquaculture Department.

As shared by Cabacaba, the modified hatchery protocol methods include 1) hatchery facilities preparation; 2) natural food (e.g. microalgae, zooplankton, and brine shrimp for the different stages of zoea) production; 3)  berried crabs sourcing and selecting; 4) zoea hatching and stocking in rearing tanks; 5) feeding zoea to crab instar or juveniles; 6) changing the water in the rearing tanks and daily monitoring its parameters; 7) placing B-nets as shelter for crablets to prevent or lessen cannibalism in the nursery tanks; 8) feeding minced fish or crab instar shells to juvenile crabs; 9) harvesting and counting of crablets; 9) packing crablets in fry bags with shelter and oxygen; and 10) releasing and reseeding hatchery-bred crablets in suitable reefs and seagrass areas in Guiuan and Salcedo, Eastern Samar.

Along with this, the DA-NFRDI-MFRDC, DA-Bureau of Fisheries and Aquatic Resources-Guiuan Marine Fisheries Development Center, and the DA-Office of the Municipal Agriculturist of Guiuan urged small-scale crabbers, crab buyers, and crab sellers in the area to follow the regulations set by the Joint DA-Department of Interior and Local Government Administrative Order 01-2014 on the conservation of BSC. This includes prohibiting the transport and trading of gravid blue swimming crabs. Crabbers were also provided with lying-in or holding cages used as containment for caught berried crabs and placed in sanctuaries until eggs are released. 

“Stock enhancement is a good way to replenish the depleted BSC stock in the wild to ensure the sustainability of the resource while sustaining market demand. However, its effect could be evident if there is successive release of crablets every other month and is conducted in a longer period of time,” concluded Cabacaba. (### MARIA ELENA M. GARCES)