This paper analyses, using a qualitative methodology, some of the possible causes of the recognized failure of fisheries policy concerning traditional fisheries. Through a case study in a Spanish Mediterranean port (Gandia), it concludes that the basic problem is the lack of legitimacy of political institutions for fishermen. Any attempt to implement an effective fisheries management must recover this legitimacy, by harnessing existing social capital of these communities through the adoption of new models of fisheries co-management and the revaluation of local knowledge. The authors would like to thank the Spanish Economy and Competitiveness Ministry for its support through the Research Project (CSO2013-41972-P) Herrera Racionero, P.; Lizcano-Fernandez, E.; Miret Pastor, LG. (2015). Us and them. Fishermen from Gandía and the loss of institutional legitimacy. Marine Policy. (54):130-136. https://doi.org/10.1016/j.marpol.2014.12.018