Simulating trophic impacts of fishing scenarios on two oceanic islands using Ecopath with Ecosim

Abstract

The ecological system conformed by the islands of Tenerife and La Gomera (Canary Islands) is characterized though the trophic network. The indicators obtained by the Ecopath model show a stressed and still developing ecosystem, probably related to inadequate management of the fisheries that takes place in this area, focused on high trophic level species. The Ecosim and Ecospace modules have been used to provide comparative assessment of three management scenarios addressed to evaluate the impact of fishing, both professional and recreational, on the marine ecosystem, as well as the spatial evolution of the fishing effort in a projection period going from 2021 to 2030, that can be applied in decision-making and planning in the short and medium term. In all the simulated scenarios, a drastic reduction in the biomass of pelagic species was observed, including the trophic guild of pelagic sharks that the model identifies as key species for the correct functioning of this marine ecosystem. Despite the existing information gaps, the results seem to confirm that the intense exploitation to which some functional groups have been subjected in the past has left its mark on the ecosystem, requiring a significant fishing effort reduction to attempt a recovery of the stocks. It is strongly recommended the implementation of a recreational fishing data collection system with less uncertainty, due to its significant role in the state of this ecological system.