Dynamic ecosystem models and the evaluation of ecosystem effects of fishing: can we make meaningful predictions?

Abstract

Abstract Fishing is one of the most widespread anthropogenic impacts on marine ecosystems. In recent times, the development of measurable metrics of the resultant ecosystem effects, has become an important aspect of fisheries management. Ecosystem models are often advocated as tools for the evaluation of system effects, but the extent to which models are able to make meaningful predictions, has not yet been fully addressed. In order to assess the suitability of models, to evaluate ecosystem effects of fisheries, the direct and indirect effects were catalogued. From the literature, 33 applications of marine ecosystem models were identified for analysis of their ability to fully assess these catalogued effects. Analysis was possible for only 24 of the models due to poor documentation of the other 9. Each model was examined for their inclusion of nine functional groups, deemed essential for the assessment of impacts of fishing on the whole ecosystem (e.g. detritus, marine mammals). The models were also assessed for their inclusion of several additional factors, either fundamental in the regulation of marine ecosystems (e.g. environmental forcing), or important in the classification of their role as a predictor of changes in ecological processes (e.g. simulation, spatial properties). No model formulation provided coverage in all the areas necessary to cover the identified effects of fisheries. Eight models provided good coverage, nutrient dynamics and benthos were the least well represented aspects of the ecosystem. The ECOPATH with Ecosim family of models, the European Regional Seas Ecosystem Model (ERSEM) and the Anderson & Ursin multispecies extension to the Beverton & Holt model all seem likely to yield good insights. In further developing these models, however, consideration must be given to explicitly incorporate spatial factors and extrinsic forcing functions, such as climate. Copyright © 2002 John Wiley & Sons, Ltd.