Environmental Impact of Trawling on the Continental Shelf of Bay of Bengal

Abstract

Entire West Bengal offshore and estuaries situated on the Indian continental shelf along Bay of Bengal exhibits excellent breeding ground of uncountable marine species presenting the great marine ecosystem shared by World's largest mangrove food web famously 'Sundarbans' (World Heritage Site, 1989). This paper intensively studied Shankarpur-Digha fishing zone encouraged modern bull trawlers to drag bigger trawl nets through ocean bottom for huge commercial catch.  This non-selective fishing gear is very likely to have destroyed undersea habitat of uncountable benthic species which actually form extensively broad baseline of complex marine food chain.  If any baseline component is found damaged by anthropogenic intervention, entire marine food pyramid must be collapsed posing threat to all top consumers. Trawling is proved to destroy huge non-economic but ecologically worthy marine juveniles occupied primary and secondary trophic levels, creating great food crisis for all predators whose sustenance is suspected to be at stake. Resultantly the apex species are also bound to face food crisis, ultimately leaving whole seafood- dependent coastal fisherfolk the worst sufferer. Benthic nutrients deposition and growth is proved getting thinner with increasing offshore distance and depth showing higher biodiversity loss by trawling near the coast. Unfortunately, most trawlers in West Bengal offshore practice fishing in biodiversity-enriched shallower water to ensure highest catch with maximum profit damaging the submarine ecosystem maximum.  This study statistically quantified trawl induced biodiversity loss along with chemical disturbances in submarine soil and water and suggested effective Environmental Management Plan to ensure conservative use of marine resources for a sustainable marine ecosystem not only in West Bengal offshore but also applicable to all tropical trawling grounds of the world.

Keywords: Offshore ecosystem in West Bengal;  Largest mangrove food web;  Commercial trawl netting;  Affected benthic environment;  Sustainable development.