Effects of Set Bagnet fisheries on the shallow coastal ecosystem of the Bay of Bengal

The coastal ecosystem of the Bay of Bengal (BOB) is described using a mass-balance model of trophic interactions to understand the effects of Set Bag Net on the ecosystem. The BOB model had 14 functional ecological groups; 13 living and one dead (detritus). The result showed that the fishery was heavily exploited and operated at a mean trophic level of 2.45. The SBN fishery was characterized with high fishing mortality rates and large omnivory indices for most of the commercially exploited demersal and pelagic groups. The total primary production requirement for sustainable catch was estimated at 15.11%. However, results of Ecosim simulations elucidated that the key resources, like small demersal, small to medium pelagic fish groups and penaeid shrimps, were likely to show a rapid decline in yields within five years with a twice increase in fishing effort and pressure. In contrast, the palaemonidae and sergested shrimp yields showed an increasing trend as they seem to be able to sustain the high fishing pressure, since their predators are also harvested. In addition to that, cephalopod, which is a non-targeted group for this fishery, is also likely to increase in yield for the time being. The two most drastically affected groups in both fisheries were likely to be shark and small demersal. Continuously increasing fishing effort using SBN will lead to a rapid decline of most of the commercial marine resources and predicted to have a serious effect on the ecosystem functioning of BOB.