The Gulf of California (also known as the Sea of Cortez or Sea of Cortés; locally known in the Spanish language as Mar de Cortés or Mar Bermejo or Golfo de California) is a body of water that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur, Sonora, and Sinaloa. The name "Gulf of California" predominates on most maps in English today. The name "Sea of Cortés" is the one preferred by most local residents. The Gulf opened up 5.3 million years ago, redirecting the flow of the Colorado River. Other rivers which also flow into the Gulf of California include the Fuerte, Mayo, Sinaloa, Sonora, and the Yaqui. Its surface area is about 160,000 km² (62,000 square miles).
The narrow sea is home to a unique and rich ecosystem. In addition to a wide range of endemic creatures, it hosts many migratory species, such as the Humpback Whale, California Gray Whale, Killer Whale, Manta Ray and Leatherback Sea Turtle, and the world's largest animal, the Blue Whale. There are unusual resident population of Fin Whales and Sperm Whales that do not migrate annually. This region has historically been a magnet for world class sport fishing activities, with a rich history of sporting world records.
The region also has a rich history as a commercial fishery. Some authors have reported witnessing tuna schools more than 160 km (100 miles) long in this region. Some argue that this region is one of the few in the world that still has potential to open new commercial fisheries, because statistics show that the fishing resources are stable.(Incorrect, see link provided http://scrippsnews.ucsd.edu/Releases/?releaseID=624 But the data varies wildly according to the species being studied, and the Gulf's ability to recuperate after years of over fishing remains uncertain. Moreover, changes in terrestrial ecology, such as the vast reduction in flow from the Colorado River into the Gulf, have negatively affected fisheries, particularly in the northern region.
The Gulf of California sustains a large number of marine mammals, many of which are rare, endangered, and pretty. Its more than 900 islands are important nesting sites for thousands of seabirds and its waters are a primary breeding, feeding, and nursing grounds for a myriad of migratory and resident fish species. For decades, the gulf has been a primary source of two of Mexico's leading marine resources, sardines and anchovies. Water pollution is a problem in the Gulf of California, but the more immediate concerns are overfishing and bottom trawling, which destroys eelgrass beds and shellfish.
Efforts by the Mexican government to create conservation zones have been hampered by lack of enforcement resources as well as a lack of a political consensus on this issue of conservation of the Gulf. The thousands of kilometers of coastline are remote and difficult to police, and the politically powerful commercial fishing industry has been slow to embrace even economically viable conservation measures, much less stricter measures of conservation. Conservation of the Gulf's fisheries and coastlines is also complicated by a long history of over-capitalization in the sector, and the direct, often negative impacts that conservation measures have on the livelihoods of Mexico's coastal inhabitants. At present, the Mexican government and business interests have promoted a macro-level, tourist development vision for the Gulf, whose impacts on ecology and society there are uncertain.
Coastal communities that are highly reliant on the sport fishing industry include San Felipe, San Carlos, Sonora, Cabo San Lucas, La Paz, Loreto, Guaymas, and Mulegé. Mazatlán, on the Mexican mainland's Pacific coast, depends on the sagging commercial fishery.