Modeling the impacts of fishing regulations in a tropical Indian estuary using Ecopath with Ecosim approach.

Abstract

In this study, we measured the impacts of an efective fshing regulation on the sustainability of fsheries in Zuari estuary, a tropical estuary situated along western coast of India through an Ecosim approach. Ecosystem indicators for 2016 and 2031 (for each Ecosim scenario) were measured to compare and contrast the decadal changes in the status of the ecosystem between these two periods. Four diferent hypothetical fshing patterns were simulated to explore the best suited management scenario. The ecosystem indices of 2031 ecosystem were compared with that obtained for 2016 to evaluate the possible efects of fshing regulations. The functional groups showed a decline in their biomass when no fshing regulations are implemented (S1). The direct fshing efort reductions of all the feets (S4) and ban/reduction of indiscriminate fshing feets (S2-immediate ban and S3-gradual reduction) showed a more or less similar trend for recovery of fsh stocks through diverse fsheries policies. A complete ban of indiscriminate fshing seems to slightly more advantageous than the direct reductions in the fshing efort for all the feets in terms of stock recovery (130%), Q statistic (1.15), Shannon diversity (1.43), mean trophic level of ecosystem (2.98), mean trophic level of the catch (2.91) and fsh catch in the gillnet feet (200%). The simulations have also suggested that a complete control for mechanized fshing feets will be the best possible management strategy for the recovery of fsh stocks in the ecosystem.