---
id: engines/ecopath-with-ecosim
about:
  label: Ecopath with Ecosim
  description: >-
    Free, open-source software for modelling food webs: a balanced snapshot of
    who eats whom (Ecopath), a simulation over time for fishing and policy
    (Ecosim), and a spatial version for protected areas (Ecospace).
  tags:
    - food web
    - fisheries
    - marine protected areas
    - ecosystem model
    - contaminants
tool:
  form: desktop modelling suite
  group: Wildlife and oceans
  homepage: 'https://ecopath.org/'
  cost: free
domains:
  - ecology
  - food
  - water
open:
  source: open
  data: unknown
  api: unknown
  participation: open
  note: >-
    The site calls the source code open and lets anyone extract it without an
    account, but names no licence. Releases are on GitHub and citable versions
    on Zenodo.
provenance:
  origin: agent
  sources:
    - title: Ecopath with Ecosim
      url: 'https://ecopath.org/'
  created: '2026-10-23'
  reviewed: '2026-10-23'
  reviewed_by: 'Claude, from the source listed'
  status: draft
---
Ecopath with Ecosim (EwE) models an ecosystem as a food web. Ecopath is the snapshot: how much of each group of animals and plants there is and how energy flows between them, balanced so that what is eaten adds up.[^1] Ecosim runs that web forward in time, so a user can ask what a change in fishing, or a policy, would do to everything else.[^1] Ecospace spreads it across a map and is mostly used to judge where marine protected areas should go and what they would do.[^1]

Fishing and protected areas are its main uses.[^1] A module called Ecotracer follows how a contaminant moves through the food web and where it accumulates.[^1] After an [oil spill](/questions/after-an-oil-spill/) that is one of the questions left open.

The software is free, and the Ecopath International Initiative, a not-for-profit research association, maintains it.[^1] Downloads are at ecopath.org, releases on GitHub, and citable versions on Zenodo.[^1]