World Conference on Natural Resource Modeling

The Tragedy of Open Ecosystems

High Country Conference Center

This paper investigates the role played by cooperation for the sustainable harvesting of an ecosystem. To achieve this, a bio-economic model based on a multi-species dynamics with interspecific relationships and multi-agent catches is considered. A comparison between the non cooperative and cooperative optimal strategies is carried out. Revisiting the tragedy of open-access and over exploitation issues, it is first proved analytically how harvesting pressure is larger in the non cooperative case for every species. Then it is examined to what extent gains of cooperation can also be derived for the state of the ecosystem. It turns out that cooperation clearly promotes every species conservation when the number of agents is high. When the number of agents remains limited, results are more complicated especially if a species by species viewpoint is adopted. However, we identify two metrics involving the state of every species and accounting for their ecological interactions which exhibit the gains of cooperation at the ecosystem scale in the general case. Numerical examples illustrate the mathematical findings.