The northern elephant seal lives in the eastern Pacific Ocean, along the coasts of California and Baja California, mainly on offshore islands, where it mates, gives birth and moults, but migrates north to Alaska and to British Columbia.
While the pelagic range covers a huge area, there are only seven main spawning areas, four of which are located on islands off California. A large population increase has recently been observed in the Gulf of California. Large colonies can be observed in Año Nuevo State Reserve, at the Piedras Blancas Lighthouse and in Morro Bay State Park.
At the end of the 19th century they were almost extinct, as their number was between 100 and 1000 specimens. These few remaining specimens, at the beginning of the last century, found refuge in the Mexican waters, on the island of Guadalupe, where there was only one reproductive colony.
The Mexican government, fortunately, guaranteed this colony total protection. Since the early 20th century, this species has been protected in both Mexico and the United States. Subsequently, under the US protection of the Marine Mammal Protection Act, their number increased again up to the current over 100,000 specimens.
In California, the population is continuing to grow 25 percent each year and more and more new colonies are forming; from now on, their number will be limited only by the lack of available space. However, these animals are always under threat from El Niño and the climate changes it brings.
In California, over the past fifty years, the number of colonies of these animals has experienced a significant boom. In Año Nuevo State Park, for example, not a single specimen of these seals had been sighted until the 1950s, but already in the early 1960s the birth of a young had already been reported.
Nowadays, thousands of young are born in Año Nuevo every year, both on the island and on the mainland. The restocking near San Simeon was even more spectacular: before 1990 there were no specimens. There are now more specimens in San Simeon during the winter than in Año Nuevo State Park.