PCC-CRE Locally Hatched Mangrove Crab

Thursday, March 30, 2017
In support of Palau’s aquacultural development in the area of commercial farming, the Cooperative Research & Extension of Palau Community College (PCC-CRE) recently implemented a project that supports the local pro- duction of mangrove crab. To address the diminishing stock of mangrove crabs Scylla serrata locally known as “chemang” in Palau waters, the Palau Community College in collaboration with the Ngeremlegui State Rangers had recently installed a mangrove crab seed bank in one of the mangrove conservation areas located in Ngeremlengui State. This was done following a recommendation of visitors from the Embassy of Thailand in February 2017. During their visit, the team of experts from Thailand gave an informative presentation on how to commercialized mangrove crab by maximizing the output of crab seeds and minimize greater loss.

The team recommended the establishment of “crab banks”to help enhance the mangrove crab fishery by allowing the captured berried crabs to release their seeds to the wild before these are sold to the market.To initiate this project, the Thai Embassy donated 2 sets of 5mx 5m net cages including ropes and plastic containers that will be used to hold the berried crabs in the water before release their hatched larvae. On March 9, 2017 a berried crab that spawned at PCC hatchery carrying about 6 million eggswas placed inside the crab seed bank a day before the eggs are expected to hatch. On the same date about 3 million newly hatched mangrove crab zoea were released at the said site after a million zoea have been utilized for stocking in the hatchery tanks for crablet production.
On March 27, 2017, A local crab farmer, Mr. Carlos Wasisang from Ngchesar State requested a total of 1,200 pcs crablets of mangrove crabs with about ½ inch in carapace length that were produced at PCC hatchery delivered to his mangrove crab farm in Ngchesar State. This is in support of Mr. Wasisangs interest on mangrove crab farming. Based on our inspection of Mr. Wasisang’s mangrove crab farm with the dimension of 20 meters x 40 meters, it could accommodate an initial stocking of about 1,000 crablets (1.5 to 2 inches carapace length). These crablets will be fed with fish by-catch such as sardines and other low value fish, fish entrails, and other aquatic invertebrates for about 6 months when they can reach the marketable size. In order to keep the crabs within the area, a perimeter fence made of either stainless screen or polyethelene mesh net with an opening of about ½ inch must be installed as shown in the attached pictures. The density of mangroves within the proposed site is just enough to provide natural hide-out and shelter for the crabs. These will serve as refuge to the crabs since the substrate becomes exposed during the lowest tide. Growing the crabs inside the mangroves does not create a negative impact to the surrounding environment and with proper feeding management and monitoring of stock, it could be able to attain a sustainable yield. PCC CRE continue to work with the local farmers interested in such aquaculture project to increase sustainability and food security in Palau.