How Persistent Are the Effects of Enforcement?

Abstract

Governments seeking to protect marine resources face a basic constraint: fishing vessels operate continuously, but costly patrols cannot. Whether intermittent enforcement provides meaningful protection depends on how vessels respond while patrols are active and how quickly they return afterward. I study these responses in The Gambia, combining satellite observations of vessel presence with records of enforcement campaigns. The estimates suggest that campaigns temporarily reduce vessel presence by approximately 12 percent across Gambian waters and 38 percent in the nearshore zone reserved for small-scale fishers, relative to predicted levels without enforcement. Some activity is displaced toward neighboring Senegalese waters. Overall Gambian presence returns close to its predicted no-enforcement level within two to four weeks after the final recorded arrest. These findings suggest that a successful campaign need not deliver lasting protection. Evaluating fisheries enforcement therefore requires considering not only its immediate effect, but also when deterrence must be renewed and where displaced activity goes.