The objective of this research is to assess the main social and economic effects on local fishermen in El Golfo de Santa Clara, as a result of the severe fishing restrictions enforced to protect the marine mammal “vaquita” (Phocoena sinus). Sustainable development includes natural resources conservation and the improvement of the social and economic conditions of local inhabitants. In Mexico, the vaquita is in imminent danger of extinction. It is a marine cetacean endemic to the Upper Gulf of California. Conservation measures to save this species, such as gear-switching and transformation subsidies from fishing activities to tourist services, have caused severe social and economic impacts on the local fishermen of this region. Presently, it is estimated that there are only 30 vaquita individuals left in the wild, and none are in captivity. In this study, we conduct surveys of the human local population involved in the incidental bycatch fishing of the vaquita, and also use secondary sources to come up with recommendations, based on taking into account stakeholder needs. For this fishing community the economic and social problems have worsened because currently there are limited economic activity options in the area for the human population, and the vaquita population continues to decline. Recommendations are offered to contribute to the ecological sustainability of this species, and for economic and social sustainability of local fishermen.