Z.c. californianus is found along the coast of the eastern North Pacific, from southern British Columbia to western Mexico including Baja California. California sea lions breed on islands off the coasts of California and Baja California, including the Channel Islands, Guadalupe, San Benitos, and Cedros. They also breed on the coast and islands of the Gulf of California, and the Mexican Pacific coast as far south as Isla Tres Marias.
Z.c. wollebaeki is found mainly on the Galápagos Islands. Some are occasionally spotted off the coasts of Ecuador and Columbia
Z.c. japonicus was once found on a select few Japanese islands. Some researchers believe that there are individuals of this subspecies on Takeshima Islands (now claimed by South Korea). Most researchers believe this subspecies is extinct.
California sea lions inhabit rocky and sandy beaches of coastal islands and mainland shorelines. They may frequent sandbars; sheltered coves; tide pools; and structures such as piers, jetties, and buoys.
During the nonbreeding months, most males migrate north from breeding grounds. Southern California males migrate to Puget Sound, Washington and British Columbia; males from Baja California migrate to the Channel Islands.
Most females either stay within their breeding grounds or move south during nonbreeding months.
The Z.c. californianus population is estimated at about 237,000 to 244,000.
- Studies have suggested that the California sea lion population in the United States has possibly increased at an average annual rate of 10.2% since 1983. The Mexico population has remained stable.
- One of the largest breeding rookeries is found on the Channel Islands. In 1990 the Channel Island population was estimated to be about 89,000 animals, based on a pup count of 25,000.
- California sea lions are not endangered or threatened.
The Galápagos population is estimated at 20,000 to 50,000. This population is listed by the IUCN as "Vulnerable".
The Japanese population was estimated in the 1950s to be 200 to 300, but is currently presumed by most researchers to be extinct.