Mangrove-friendly crab culture, a lucrative source of livelihood

first_imgBased on a pilot-project in Palawan, a 4,000 square meterpen which was stocked with 2,040 pieces of crablets yielded 1,767 market-sizedcrabs weighing an average of 275 grams. The crabs were partially harvestedbeginning the third month until the sixth month. In all cases, mangrove crabs are marketed alive. With pricesnow upwards of P500 per kilogram, crab culture among mangroves might just beanother reason for coastal communities to protect their mangrove resources./PN According to a manual authored by SEAFDEC AquacultureDepartment chief Dan Baliao, growing alimango among mangroves mainly entailsstocking wild or hatchery-sourced crablets within a manageable area of between2,000 square meters to 1 hectare enclosed with nets or bamboo slats. The shapeof the area will depend on the topography and distribution of trees and roots. THE lush foliage of mangrove forests is now the pride oftheir host communities – a badge for environmental conservation, a naturalprotection from storm surges, and a potential tourist draw. This is a far cryfrom the times mangrove areas were seen as unproductive wastelands and weresoon cleared to make way for aquaculture ponds. Monosize crablets weighing between 30 to 50 grams each maybe stocked at 5,000 to 10,000 pieces per hectare. Crabs are fed with choppedtrash fish, animal entrails, mussel and snail meat, whichever is locallyavailable and economical. These are broadcast daily beginning at 10 percent ofbiomass before tapering to five percent towards the end of a culture periodthat may last between 45 and 60 days or when they reach at least 200 grams. Another important component is ditches that will serve asrefuge for the crabs. These should be able to hold water during the lowest lowtide and cover between 20 and 30 percent of the enclosure area. While minorroots of mangroves will likely be affected by the digging, cutting main rootsshould be avoided. Growing ‘alimango’ in mangrove pens While aquaculture appears to be the main culprit for thedestruction of mangroves in past decades, they are not mutually exclusive.Farming of fish, shrimps, and crabs within mangrove areas – termedaquasilviculture – may be done to combine the benefits of coastal protection,ecological productivity, and livelihood for nearby communities. Because some crabs tend to dig, enclosures should extend upto 70 centimeters beneath the soil. Meanwhile, the top should be not less than30 centimeters above the highest high tide. Crabs should also be prevented fromclimbing over the pen using a 30-centimeter net overhang or plastic lining ontop of the fence. “Mud crab culture in mangrove pens is the most lucrative andenvironment-friendly mangrove-friendly aquaculture system,” says Dr. JurgennePrimavera, scientist emerita of the Southeast Asian Fisheries DevelopmentCenter (SEAFDEC), referring to the grow-out of crabs, also locally known as alimango,a prized commodity with year-round demand in the market. Considering the natural ebb and flow of tidal waters withinmangrove areas and the obstruction of trunks and roots, aquasilviculture is notas straightforward as pond culture where the water level may be controlled.However, farming amphibious mangrove crabs, also called mud crabs, is seen asthe best option for aquasilviculture. Market-sized mangrove crabs harvested from SEAFDEC’s Dumangas Brackiswater Station. Photo courtesy of SEAFDEC/AQD. By Rex Delsar B. Dianalalast_img read more

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