Paper Title
CHALLENGE TO COMBAT TRAWL DEGRADATION IN MARINE AND ESTUARINE MANGROVE ECOSYSTEM

Abstract
Abstract - Immensely broad continental shelf of Bengal offshore and estuary, covering the ‘Sundarbans’, largest mangrove ecosystem (World Heritage Site, 1989) developed huge phyto-planktons reserve as broad baseline of marine mangrove food web with various marine species occupying higher trophic levels. Growing population forced intensification of estuarine and offshore trawl netting, a non-selective fishing gear, continuously dragged through ocean bottom for huge catch, scooping out sea-floor biodiversity destroying at random the under-sea habitat of innumerable baseline species. Trawling mortality seems to have already started evitable collapse of entire marine food pyramid endangering all top consumers even coastal humans. Environmental impact of trawling mortality in Tajpur-Shankarpur-Digha-Petua fishing zone has been proved through experimental trawl cruises, sampling, testing and statistical analysis. As biodiversity richness is proved inversely related to offshore distance, marine biodiversity loss decreases with increasing depth and starting distance of trawling. So, shallower continental shelf with maximum benthic nutrient deposition, shows higher trawling mortality indicating higher benthic biodiversity loss and vice versa. Trawling mortality is proved here as a response to or a great impact of Starting distance of trawling, Total trawling mileage and Depth of trawling by individual trawler. Abrupt hype in sea water Ph also proves maximum trawling mortality near the coast. Trawl induced lead and copper pollution is proven higher in deep sea fishing fields and estuarine trawl resting spots. Continuous trawling mortality triggered by soil and water degradation with random mangrove destruction caused great food crisis for apex species like shark, dolphin and seal, absence of prawn seedlings, sea conches and total extinction of Chandana Hilsa, widely available thirty years ago in Bengal offshore. Environmental Management Plan includes curative measures highlighting preventively compulsory ban on trawling, night and monsoon trawling and mandatory use of trammel net. Poorer selectivity and minimum sea bed contact of trammel net offers minimum abrasion keeping thick undersea biodiversity mostly intact safeguarding the baseline of largest mangrove ecosystem. Keywords: Ecologically unique largest Mangrove ecosystem; Trawl impact on estuarine environment; Trawl damage to marine mangrove ecosystem; Loss of marine biodiversity; Conservation for sustainable marine environment