The ecological effects of fishing and implications for coastal management in San Miguel Bay, the Philippines

This article uses ecological theory to explore the interactions between fishing and the ecosystem and to examine the implications for fisheries assessment and management in San Miguel Bay, the Philippines. The fishery is modeled using a trophodynamic multispecies model, Ecopath with Ecosim. The impacts of fishing by a multisector fishery on a multispecies resource were dynamically explored under top-down and bottom-up trophic hypotheses. The results demonstrated that the interplay of fishing mortality, species interactions and flow dynamics can have profound implications for fisheries assessment and management. Top-down control is more precautionary than bottom-up control. The uncertainties concerning the resource dynamics were explored using an adaptive management approach. Four models of the San Miguel Bay were analyzed: top-down, bottom-up, immigration plus top-down and immigration plus bottom-up. Results showed that there was no value in learning more about the uncertainty or distinguishing between the different resource models. It was concluded that although an active experimental adaptive management was not worthwhile, adaptive management, using feedback information from the response of the resource to management actions, was recommended.