Ecopath with Ecosim ( EwE ) is a free ecosystem modeling software suite , originally started at NOAA by Jeffrey Polovina, but has previously been developed at the UBC Fisheries Center of the University of British Columbia . In 2007, it was named as one of the biggest scientific breakthroughs in NOAA’s 200-year history. The NOAA states that Ecopath “revolutionized scientists’ ability worldwide to understand complex marine ecosystems”.  Behind this binds more than two decades of development work in association with Villy Christensen , Carl Walters , Daniel Pauly, and other fisheries scientists ,  followed by the provision of user support, training and co-development collaborations. There are 6000+ registered users in 150+ countries.
EwE has three main components:
- Ecopath – a static, mass-balanced snapshot of the system 
- Ecosim – a dynamic time module simulation for policy exploration 
- Ecospace – a spatial and temporal dynamic module primarily designed for exploring the 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 
- impact and placement analysis of marine protected areas 
- prediction and accumulation of contaminants and tracers (Ecotracer) 
- model effect of environmental changes,  
- facilitate end-to-end ecosystem model construction 
The desktop version of Ecopath with Ecosim runs on Windows and requires Microsoft Access database version 2007 or newer. The computational core of Ecology with Ecosim can be executed on other operating systems such as Unix or Linux using the Mono common language runtime . 
Development Ecopath version 6  received support from the Lenfest Ocean Program and the Pew Charitable Trusts . In 2011 the Ecopath Research and Development Consortium was founded to share the responsibility of maintaining and further developing the approach to institutions around the world.
- Jump up^ NOAA, 2007. ECOPATH Modeling: Precursor to an Ecosystem Approach to Fisheries Management [WWW Document]. URLhttp://celebrating200years.noaa.gov/breakthroughs/ecopath/welcome.html(accessed 8.26.12).
- Jump up^ Smikle, SG, V. Christensen and KA Aiken (2010). “A review of Caribbean ecosystems and fishery resources using ECOPATH models”. Caribean Studies Review, No. 15, https://caribbeanstudies.revues.org/4529
- Jump up^ Christensen, V. and Pauly, D., 1992. Ecopath II – a software for balancing steady-state ecosystems and calculating network characteristics. Ecological Modeling, 61: 169-185.
- Jump up^ Walters, C., Christensen, V. and Pauly, D., 1997. Structuring dynamic models of exploited ecosystems from trophic mass-balance assessments. Rev Fish Biol Fish, 7: 139-172
- Jump up^ Walters, C., Pauly, D. and Christensen, V., 1999. Ecospace: Prediction of mesoscale spatial patterns in trophic relationships of exploited ecosystems, with emphasis on the impacts ofmarine protected areas. Ecosystems, 2: 539-554.
- Jump up^ Christensen, V. and Pauly, D. (Editors), 1993. Trophic Models ofAquatic Ecosystems. ICLARMConference Proceedings 26, Manila, 390 p.
- Jump up^ Walters, CJ, Christensen, V., Martell, SJ and Kitchell, JF, 2005. Possible ecosystem impacts of applying MSY policies from single-species assessment. ICES J Mar Sci, 62: 558-568.
- Jump up^ Christensen, V. and Walters, CJ, 2004. Trade-offs in ecosystem-scale optimization offisheries managementpolicies. Bull Mar Sci, 74: 549-562
- Jump up^ Walters, CJ and Martell, SJD, 2004. Fisheries Ecology and Management. Princeton University Press, Princeton, 399 p.
- Jump up^ Christensen, V. and Booth, S., 2006. Ecosystem modeling of dioxin distribution patterns in the marine environment. Chapter 6. In: J. Alder and D. Pauly (Editor), On the multiple uses of smallpelagic fishes: from ecosystems to markets. UBC Fisheries CenterResearch Reports14 (3). Fisheries Center, University of British Columbia [ISSN 1198-6727], Vancouver
- Jump up^ Guénette, S., Heymans, JJ, Christensen, V. and Trites, AW, 2006. Ecosystem models, Steller sea lions (Eumetopias jubatus) in Alaska. Can J Fish Aquat Sci, 63: 2495-2517.
- Jump up^ Christensen, V., Coll, M., Steenbeek, J., Buszowski, J., Chagaris, D., and Walters, CJ, 2014. Representing Variable Habitat Quality in a Spatial Food Web Model. Ecosystems 17, 1397-1412.
- Jump up^ Steenbeek, J., Coll, M., Gurney, L., Melin, F., Hoepffner, N., Buszowski, J., and Christensen, V., 2013. Bridging the gap between ecosystem modeling tools using geographic information systems: driving a food-web model with spatial-temporal primary production data. Ecological Modeling 263, 139-151.
- Jump up^ Steenbeek, Jeroen; Buszowski, Joe; Christensen, Villy; Akoglu, Ekin; Aydin, Kerim; Ellis, Nick; Felinto, Dalai; Guitton, Jerome; Lucey, Sean; Kearney, Kelly; Mackinson, Steven; Pan, Mike; Platts, Mark; Walters, Carl (January 2016). “Ecopath with Ecosim and a model-building toolbox: Source code capabilities, extensions, and variations”. Ecological Modeling . 319 : 178-189. doi : 10.1016 / j.ecolmodel.2015.06.031 .
- Jump up^ Christensen, V. and Lai, S., 2007. Ecopath with Ecosim 6: the sequel. TheSea Around Us ProjectNewsletter, 43: 1-4 (September-October).