ecological modelling 210 ( 2 0 0 8 ) 465–477 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ecolmodel Exploring fisheries strategies for the western English Channel using an ecosystem model J´ ulio N. Ara ´ ujo a,* , Steve Mackinson b , Richard J. Stanford c , Paul J.B. Hart a a Department of Biology, University of Leicester, Leicester LE1 7RH, UK b CEFAS, Fisheries Laboratory, Pakefield Road, Lowestoft NR33 0HT, UK c Devon Wildlife Trust, 35-37 St David’s Hill, Exeter EX4 4DA, UK article info Article history: Received 21 December 2006 Received in revised form 16 July 2007 Accepted 15 August 2007 Published on line 1 October 2007 Keywords: Ecopath with Ecosim Trophic level Biodiversity Fishing strategies Fishing effort English Channel abstract An ecosystem model of the western English Channel ecosystem in 1994 was used to explore the effects of the use of a fishing policy optimization routine on profits, number of jobs and ecosystem structure. The optimization for single objective led to the specialization of the fishing fleet, with some fleet types being almost excluded. The profits and mainly the job optimizations led to big changes in the ecosystem structure, with loss of diversity, but the overall biomass of all vertebrate groups represented in the model increased considerably. For the objective focusing on ecosystem structure, there was an increase in biodiversity, with many long-lived groups predicted to increase, although the overall vertebrate biomass suffered just a small increase. An “ideal” mixed policy configuration was found when slightly greater weight was given to ecosystem structure than was given to profits and jobs. This scenario led to an overall reduction in effort but also to increased profits and biodiversity, while keeping the number of jobs at the same level as the baseline estimates. The results of the optimizations showed that the average trophic level of the catches is quite resistant to changes in the underlying system structure. On the other hand, despite the high level of aggregation of the model structure, a biodiversity index estimated by the model presented large changes as a function of the weights placed on the single policy functions, reflecting the changes in the system structure. The output of the application of the fishing optimization presented here should be considered in qualitative rather than in quantitative terms as an aid and part contribution to the complicated discussions on future long term management actions. Nonetheless it points to an overall reduction in fishing capacity, an objective widely accepted within the scientific community, while keeping the fishery in a profitable state. © 2007 Elsevier B.V. All rights reserved. 1. Introduction Ecosystem models play an important role in the ecosystem approach to fisheries and the interest in the development of such models is not new. The ecosystem model of Andersen and Ursin (1977) is an example of a relatively early attempt ∗ Corresponding author. Present address: Laborat ´ orio de Nectologia, Departamento de Ecologia e Recursos Naturais, Universidade Federal do Esp´ ırito Santo, Av. Fernando Ferrari 514, CEP: 29075-910 Vit´ oria, ES, Brazil. E-mail address: julioaneves@hotmail.com (J.N. Ara ´ ujo). to set fisheries into an ecosystem context. However, its com- plexity, large input data requirements and perhaps the lack of accessibility to computer facilities have precluded its use. The progress of computation facilities that has occurred in the last 10–15 years has allowed the spread of more complex methodologies, even in the context of single-species assess- 0304-3800/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ecolmodel.2007.08.015