Cortés’s sea packs five thousand micro-invertebrate species
The Gulf of California—also Sea of Cortés or Vermilion Sea—splits Baja California from mainland Mexico, touching the states of Sonora, Sinaloa and both Baja Californias. About 1,126 kilometres long and 177,000 square kilometres in area, it ranks among Earth’s most ecologically diverse seas.
Geologists read the rocks as showing the gulf opened roughly 5.3 million years ago, when tectonic forces tore the Baja peninsula away from the North American plate and the East Pacific Rise crept up the middle of the seabed. That rift still drives volcanoes such as Isla Tortuga and hydrothermal vents, and it explains depths beyond 3,000 metres. The sea would reach as far north as Indio, California, if the Colorado River’s huge delta did not wall off the Mexicali and Imperial valleys. Rivers including the Colorado, Fuerte, Yaqui and Sonora drain into it along roughly 4,000 kilometres of coast.
It holds 37 major islands, led by Ángel de la Guarda and Tiburón, mostly on the western side and many born from separate volcanic events, plus more than 900 islets and islands in all. Mexico declared them a migratory bird and wildlife refuge on 2 August 1978 and a flora and fauna protection area in June 2000. Tides reach 5 metres in the north, and brief violent storms called chubascos batter otherwise sheltered shores. Water typically runs from 16 °C in winter to 24 °C in summer, though La Paz hits 30 °C in August while nearby Cabo San Lucas stays near 26 °C; rare northern cold snaps below 8 °C kill off algae and plankton.
Endemic species include the critically endangered vaquita, a porpoise found only in the northern gulf, while visitors range from humpback and gray whales to manta rays, Humboldt squid, leatherback turtles and blue whales. Fin and sperm whales live there year-round. Scientists divide it into northern, central and southern faunal regions.
Sardines and anchovies from the gulf are among Mexico’s top marine resources, and towns from San Felipe to La Paz live on fishing. Overfishing and bottom trawling, which rips up eelgrass beds, worry conservationists more than pollution, and weak enforcement has undercut reserves despite parts of the sea being UNESCO World Heritage.
Source: Gulf of California
