ABSTRACT
In 1539, Hernán Cortés sent Francisco De Ulloa with three ships to explore north from Acapulco. De Ulloa reported that the island of Calafia (Baja California) was in reality a peninsula. De Ulloa circumnavigated the Gulf of California and named it Mar Bermejo, the Vermilion Sea, because of the reddish color of the muddy waters of the Colorado Estuary (León-Portilla, 1972; van Andel and Shor, 1964). The Gulf of California is very fertile, mainly due to upwelling and tidal mixing (Alvarez-Borrego et al., 1978).
