Introduction

The Ecopath with Ecosim (EwE) approach and modelling framework is designed for straightforward construction, parameterization and analysis of mass-balance trophic models of aquatic and terrestrial ecosystems. Focus is on using the models for fisheries management, and a suite of tools are included for this aim. This User Guide describes how to use the Ecopath software system, while background information and theory is available in an accompanying textbook.

The Ecopath mass-balance modelling system is built on an approach initially presented by J.J. Polovina for estimating biomass and food consumption of the elements (species or groups of species) of an aquatic ecosystem. Subsequently it was combined with various approaches from theoretical ecology, notably those proposed by R.E. Ulanowicz, for the analysis of flows between the elements of ecosystems. However, the system has been developed much further, including for direct use in fisheries management and for addressing environmental questions including climate change through the inclusion of the temporal dynamic model, Ecosim, the spatial dynamic model, Ecospace, and the Ecotracer model for tracking persistent compounds.  EwE is now used increasingly in multi-disciplinary settings, including for a wider range of application as illustrated below.