Ecopath with Ecosim (EwE) is a free ecological/ecosystem modeling software suite. EwE has three main components: Ecopath - a static, mass-balanced snapshot of the system; Ecosim - a time dynamic simulation module for policy exploration; and Ecospace - a spatial and temporal dynamic module primarily designed for exploring impact and placement of protected areas. The Ecopath software package can be used to

• Address ecological questions;
• Evaluate ecosystem effects of fishing;
• Explore management policy options;
• Analyze impact and placement of marine protected areas;
• Predict movement and accumulation of contaminants and tracers (Ecotracer);
• Model effect of environmental changes.

The latest release of Ecopath with Ecosim is version 6.3, released on November 25, 2012.