The world’s oceans provide crucial services that make our planet habitable. However, when access rights are not effectively managed over-fishing and environmental degradation threaten these services. One of the main regulatory instruments used to manage and conserve ocean resources are Marine Protected Areas (MPAs). MPAs are argued to be one of the most effective policies for restoring marine life. However, for an MPA to deliver any economic or environmental benefits it is necessary that they deliver meaningful reductions in fishing activity. Using comprehensive, global, data on commercial fishing activity we provide systematic evidence to suggest that many MPAs have not reduced fishing effort. Fishing effort is lower inside MPAs, however, much of the difference in fishing effort appears to be driven by lower returns — MPAs are located in more remote, less productive waters. Using a regression discontinuity design we do not estimate any reduction in fishing effort at the border. Using an event study approach we observe that fishing effort inside MPAs is declining prior to implementation, indicating that the timing of MPA designation, as well as the placement of MPAs, is endogenous. Our findings suggest that the efficacy of MPAs depends largely on their design and management, highlighting the importance of good governance in managing the commons.

Written with Robin Burgess (LSE), Michael Greenstone (Chicago)