Trawling Impact on Largest Estuarine Mangroves and Offshore Ecosystem

Bengal offshore and estuaries ('Sundarbans), largest mangrove ecosystem (World Heritage Site) develops huge phytoplanktons reserve as baseline of marine mangrove food web with marine species at higher trophic levels. Nonselective trawl net dragged through ocean bottom scoops out sea-floor biodiversity destroying undersea habitat of baseline species. Trawling mortality started collapsing marine food pyramid endangering top consumers, affecting coastal humans worse. Tajpur-Shankarpur-Digha-Petua fishing zone proved biodiversity richness inversely related to offshore distance, resulting in decreasing biodiversity loss with increasing depth and trawl starting distance. So shallower continental shelf with maximum benthic nutrients shows higher trawl mortality indicating higher biodiversity loss and vice versa. Continuous trawling mortality, heavy metal pollution in deep sea trawl fields and estuarine resting spots, estuarine mangroves destruction caused survival crisis for all apex species, absence of prawn seedlings, sea conches, species extinction (Chandana Hilsa). EMP highlights trammel net for poorer selectivity and minimum sea floor abrasion saving undersea baseline biodiversity.