Best practice in Ecopath with Ecosim food-web models for ecosystem-based management

Special issue Ecopath 30 years – Modelling ecosystem dynamics: beyond boundaries with EwE.-- 12 pages, 4 figures, 1 boxEcopath with Ecosim (EwE) models are easier to construct and use compared to most other ecosystem modelling techniques and are therefore more widely used by more scientists and managers. This, however, creates a problem with quality assurance; to address this we provide an overview of best practices for creating Ecopath models. We describe the diagnostics that can be used to check for thermodynamic and ecological principles, and highlight principles that should be used for balancing a model. We then highlight the pitfalls when comparing Ecopath models using Ecological Network Analysis indices. For dynamic simulations in Ecosim we show the state of the art in calibrating the model by fitting it to time series using a formal fitting procedure and statistical goodness of fit. Finally, we show how Monte Carlo simulations can be used to address uncertainty in input parameters, and we discuss the use of models in a management context, specifically using the concept of ‘key runs’ for ecosystem-based management. This novel list of best practices for EwE models will enable ecosystem managers to evaluate the goodness of fit of the given EwE model to the ecosystem management questionJJH was supported by the Natural Environment Research Council and Department for Environment, Food and Rural Affairs under the project MERP: grant number NE/L003279/1, Marine Ecosystems Research Programme. SM acknowledges support from Defra contract M1228 ‘Fizzyfish’ and EU FP7 GAP2, Grant agreement 266544. MC was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships to the BIOWEB project and by the Spanish National Program Ramon y Cajal. VC acknowledges support through an NSERC Discovery Grant RGPIN-2014-05782Peer Reviewe