Awareness of the limitations of a single-species approach to fisheries management has led to global acceptance of the need to adopt a wider ecosystem approach to fisheries (EAF) assessment and management. Applying EAF in management requires the application of scientific methods and tools that also go beyond the single-species approaches which used to be, to a large extent, the exclusive sources of scientific advice. Managers and decision-makers must now find management solutions that take into account the wider range of societal objectives that must be explicitly considered under EAF and the interactions in the ecosystem. Ecosystem models, i.e. models that represent a wider range of technological and ecological processes affecting the species in the ecosystem (including multispecies and whole ecosystem models), are potentially important tools for providing this wider scientific information. 

There are many different types of ecosystem models and they can vary enormously in terms of complexity. They can be used in different ways, ranging from contributing to conceptual understanding, providing information for strategic decisions through to making tactical decisions, although they are rarely used as yet for the last purpose. These guidelines were developed by a group of leading practioners in aquatic ecosystem modelling as a tool for provision of management advice. They are intended to assist users in the construction and application of ecosystem models for EAF. The guidelines address all steps of the modelling process, encompassing scoping and specifying the model, implementation, evaluation and advice on how to present and use the outputs. The overall goal of the guidelines is to assist in ensuring that the best possible information and advice is generated from ecosystem models and used wisely in management. 

The considerable uncertainties in the predictions provided by ecosystem/multispecies models notwithstanding, decisions have to be made and actions implemented to ensure sustainable and optimal utilization of marine living resources. These decisions must be informed by the best available scientific advice and, in the context of EAF, this scientific advice must include ecosystem considerations. Ecosystem models, adhering as far as possible to the best practices described here, will frequently be the best sources of such information and can lead to advice that rests on explicit and principled arguments.

In their absence, managers and decision-makers will have no choice but to fall back on their own mental models which may frequently be subjective, untested and incomplete, a situation which clearly needs to be avoided. Ecosystem models are not at the stage where a single such model could be selected as a "management" model and reliably used at the tactical level to provide management recommendations in a particular case. However, the use for this purpose of simple models with an ecosystem foundation could become more widespread in the near future. Such a foundation would be provided by evaluating these simpler "management" models using Management Strategy Evaluation (MSE), where the operating models reflecting alternative possible underlying dynamics that are used in this evaluation process would include a range of ecosystem models.

FAO. Fisheries management. 2. The ecosystem approach to fisheries. 2.1 Best practices in ecosystem modelling for informing an ecosystem approach to fisheries. FAO Fisheries Technical Guidelines for Responsible Fisheries. No. 4, Suppl. 2, Add. 1. Rome, FAO. 2008. 78p.