Luz Elba Torres Guevara

• This dissertation investigates factors influencing collective action in the management of the Ciénaga Grande de Santa Marta (CGSM) fishery. The CGSM is an estuarine lagoon located in the Caribbean coast of Colombia and it is one of the most important fisheries in the country. Formally, it is part of various conservation regimes, but it is under a de facto open access regime. The thesis presents the results of three research articles. The first article investigates why collective action for a sustainable use of the CGSM’s fishery resources has not taken place. For this purpose, Elinor Ostrom’s diagnostic Social-Ecological System framework (2009) was adapted to this coastal ecosystem. In the second article, individual and composite indicators were built to investigate the ecological impact of fishing spots and fishing gear/methods used by the CGSM’s fishermen from two different points of view, from (1) a group of experienced fishermen and (2) a group of experts with extensive knowledge on that fishery. Likewise, the influence of socioeconomic and perceptional factors on fishing behavior of the CGSM’s fishermen and how this behavior may be impacting CGSM fishery resources were analysed. The third article examines if fishermen’s contributions to a one-shot public goods experiment, together with their decisions in two time preferences experiments, can predict the level of ecological impact they exert on the CGSM’s fishery resources in real life. Therefore, it examines the external validity of these experiments. The results show that collective action in the CGSM is contextually related to the social, economic and political settings, and a lack of problem recognition among some fishermen. Likewise, they have shown that cooperation among fishermen is possible in the experiments but outside of the experimental setting it is necessary to address the contextual factors in order to promote collective action.