Monitoring and enforcement considerations have been largely ignored in the study of fishery management. This paper explores this issue with a formal model of fisheries law enforcement to show how fishing firms behave and fisheries policies are affected by costly,imperfect enforcement of fisheries law. This model combines standard Economics of Fisheries analysis with the Theory of “Crime and Punishment” of Becker. The conclusions of the model are used to discuss the reform of the control and monitoring regime of the Common Fisheries Policy.