Impact of converison of mangrove ecosystem for aquaculture purposes

Abstract

Mangroves, one of the highly productive ecosystems are considered as nature's own aquaculture systems because species of marine fishes, molluscs and crustaceans use tham as nursery grounds. Thus the mangrove ecosystem sustains tremendous fishery resources. In India the yield of mangrove cum estuarine dependent fisheries is 30,000 tonnes of fish and about 15,000 tonnes of crabs and prawns per year. Crustaceans like Penaeus monodon, P. indicus and fishes like Etroplus sp., mullets, etc are common in Indian mangroves. Conversion of mangroves for coconut and paddy cultivation alongwith setting of fish ponds is an age old practice in coastal India and is called as 'filtration' or 'trapping'. The brackish water aquaculture covers an area of 45,000 hectare are produced. The species cultivated are mugil cephalus, Chanon-Chanos, Penaeus Monodon, P. indicus, Macrobrachium, etc. About 32.13% of this area is along west coast and the yield rate is about 500-600 kg/ha/yr. Some of the impacts of conversion of mangrove ecosystem for aquaculture purposes are discussed in the present paper. Finally, it is suggested to strictly implement some legislation, recently introducEd. by Ministry of Environment and Forest for the conservation of coastal zones like mangroves.