This paper presents findings from an experimental study on the harvesting behaviour of a set of fishers on Colombia's Pacific coast under both the presence and absence of Territorial Use Rights for Fisheries (TURF). The experiments are common-pool resource (CPR)-games where participants undertake harvesting decisions under a baseline scenario and two subsequent treatments (communication and self-regulation). The data are analysed using different statistical models. We find that fishers under TURF tend to coordinate their efforts when no treatments are introduced into the experiment. However, once treatments are introduced, we observe that self-regulation outperforms communication in reducing harvest levels. This situation can be viewed as a consequence of the internal struggles between TURF fishers, highlighting the need for regulation. We conclude that a TURF designation on its own is not sufficient to shape the preferences of the users of a CPR and needs to be accompanied by regulation to encourage coordination among players.