Scenario testing of fisheries management strategies using a high resolution ERSEM-POM ecosystem model

摘要

Ecosystem models are jusc beginning to be considered as management tools. In terms of fishery impacts, dynamic ecosystem models provide an opportunity to make advances because they can both evaluate the state of the system and make predictions about the ecosystem under various fishing scenarios. In the framework of the Cost Impact project, a complex high-resolution (500 x 500 m grid) ecosystem model was implemented in Iraklion Bay, Crete. Several management scenarios were simulated to investigate the impacts of trawling on this particular ecosystem (reductions in fishing area, effort, and mortality). Introducing trawling impacts into the model led to increases in pelagic production. All scenarios also resulted in net increases in pelagic production, the level of which, and the degree of spatial variability, was dependent on the particular scenario. Changes in pelagic variables were often noted in areas well away from trawled areas. It was also clear that for pelagic variables and processes, depth of trawling is more important than reduction in trawling area, i.e. a scenario banning fishing in waters shallower than 100 m seems to lead to less change in the pelagic system than a scenario that reduces direct mortality to the benthos.