Deterring poaching of a common pool resource

We present results from common pool resource experiments designed to examine the ability of a group of resource users, called insiders, to simultaneously manage their own exploitation and defend their resource from encroachment by outsiders. The insiders can use communication, peer monitoring and sanctions to coordinate their decisions. In addition, they can sanction any outsiders they observe. We vary the insiders’ ability to observe and sanction the outsiders from no observability to partial and full observability. We find a striking non-monotonicity between observability of the outsiders and levels of poaching. Poaching was higher under partial monitoring than zero monitoring, and was lower and more stable under full monitoring. Although full observability allowed the insiders to better coordinate their own harvests, they were unable to fully deter poaching because their sanctions were far too low and they were unwilling to punish low levels of poaching.