The paper contributes to the social-ecological systems literature by<br />adapting and using Elinor Ostrom's Social-Ecological System (SES) framework<br />in the context of a coastal ecosystem. We modified the SES framework in the<br />case of the Ciénaga Grande de Santa Marta (CGSM), an estuarine lagoon in<br />the Caribbean coast of Colombia. The ecological importance of CGSM and its<br />species is undeniable. This paper aims to understand why collective action for<br />a sustainable use of CGSM's fishery resources has not taken place. In order to<br />respond to that question, we created new variables within the social, economic,<br />and political settings of the SES framework. The results show that the fishers' fear<br />of the indiscriminate and strong violence that illegal armed groups have inflicted<br />on them since the 1960s and the economic development in the Colombian<br />Caribbean region help explain the lack of collective action.