From the mid-fifties it has become well known that the Upper Sea of Cortés (known in Spanish as the Alto Golfo) and the delta of the Colorado River are important sites for the reproduction and breeding of many species of birds and fish. This very productive region, however, has been under heavy fishing pressure. In 1975, the totoaba fish (Totoaba macdonaldi) was facing extinction through over-harvesting. This problem forced the Federal Government to decree a moratorium for totoaba harvest in the Sea of Cortés.

Other problems, however, kept mounting. In the mid-eighties marine mammalogists started showing a strong concern on the population status of the vaquita porpoise (Phocoena sinus), which is endemic to the Upper Gulf. The vaquita is indeed a very rare marine mammal. Described in 1958, only a few specimens have been studied. The occurrence of vaquita specimens as by-catch in gill nets in the Upper Gulf started to signal an alert on Mexican and international conservation groups.

In the early nineties, the population of vaquita was estimated in less than five
hundred The vaquita was classified as endangered, and the International Whaling Commission labeled it as one of the marine mammals with the highest conservation priority in the world.It was then that the Mexican Federal Government created, through the Secretary of Fisheries, the "Technical Committee for the Protection of the Totoaba and the Vaquita" (Comité Técnico para la Preservación de la Totoaba y la Vaquita), with the purpose of evaluating and studying the issue, and
recommending adequate measures for the conservation of both endangered species.

Dr. Bernardo Villa, one of the Mexican biologists who had dedicated the most time to studying the fauna of the Sea of Cortés was named President of the Committee, which enjoyed the participation of leading Mexican biologists and conservationists. Dr. Samuel Ocaña, formerly governor of Sonora and a devoted conservationist, was appointed technical secretary of the group. After a few sessions, it became evident that serious disagreements existed between the members of the committee. While some members favored immediate action to protect the Upper Gulf of California from the devastating effects of overfishing, others were of the opinion that regulating fisheries in any way would harm the local economy.

In June, 1992, an international meeting was organized in San Diego by the University of California Mexico-US Program to discuss two conservation issues of great relevance for marine mammals: the problem of dolphin by-catch in Mexican tuna fisheries, and the totoaba-vaquita extinction threat. The meeting was called by Arturo Gómez Pompa, a professor at UC Riverside, and also at that time special advisor on environmental matters for the President of Mexico. Thus, the problem of overfishing in the Sea of Cortés started to show in the international arena, harming Mexico's reputation on conservation and natural resource management.

In 1992, a severe crisis struck the fishermen of El Golfo de Santa Clara and Puerto Peñasco, in Sonora, and of San Felipe, in Baja California. Their shrimp
		catches had fallen precipitously (Arvizu 1987), and the fishermen blamed the federal authorities in general, and the Secretary of Fisheries in particular, for failing to enforce fishing bans to allow the recovery of the resource. The idea started to grow among the fishermen that the sea had to rest and its fisheries had to recover.

In the summer of 1992, the Technical Committee met in Hermosillo, Sonora. In this meeting, both the Director General of Natural Resources (Dirección General de Aprovechamiento Ecológico de los Recursos Naturales) of Mexico's National Institute of Ecology, Exequiel Ezcurra, and Arturo Gómez Pompa, expressed their support to the idea of establishing a natural protected area in the Upper Gulf. Most members of the Committee showed sympathy for the proposal, but the representatives of the National Institute of Fisheries expressed their complete opposition. As a result, it was decided to request that the Centro Ecológico de Sonora (CES) and the Centro de Investigación y Desarrollo de los Recursos Naturales de Sonora (CIDESON) conduct a feasibility study for a Biosphere Reserve.