Even though the international trade system was originally developed without considering an environmental protection framework, efforts are being made to join environmental and political aims. In Mexico, Baja California Sur (BCS) is the most arid state and with more coastline than any other state in the country (2,200 km). The purpose of this work was to identify economic and social impacts caused, up until the present, by the North American FreeTrade Agreement (NAFTA) in BCS Yellowfin Tuna (Thunnus albacares) fisheries. We analyzed, since 1980 to 2000, the main tuna fisheries data for: growth of production, increment of quanties and value of export products, number and age of fishing vessels devoted to the tuna fishery, increase of investments in the tuna fishery sector and the generation of jobs. We found that in the short term and mid term, the North American Free Trade Agreement (NAFTA) has had no significant effects on the economic and social variables studied in the tuna fishery. In BCS tuna fishery industry must not expect significant changes, neither positive nor negative, with a free trade agreement at this level of integration