The California Sea Lion is abundant and increasing in some parts of its distribution. The total global population (US and Mexico) is probably around 355,000 individuals. Some colonies in the Gulf of California have decreased in the last two decades.

Exploitation during the 19th and 20th centuries caused population reductions. The distribution range has changed little since exploitation era but population numbers have increased mainly in California, where the estimate is around 238,000 individuals (Carretta et al. 2007). The population in Mexico occupies both side of the Baja California Peninsula: the west coast has an estimated population of 75,000 – 87,000 (Lowry and Maravilla 2005), whereas the Gulf of California populations is near 30,000 (Szteren et al. 2006). Total population of California sea lions is therefore around 355,000 individuals.

The California Sea Lion population is apparently reaching carrying capacity in the USA (Carretta et al. 2007) whereas in the Gulf of California the population has decreased by ~20% in the last 15 years (Szteren et al. 2006). The California Sea Lion has 13 rookeries from the Channel Islands to the south of Baja California and 13 rookeries inside the Gulf of California. The population in California and Baja California show declines during severe El Niño events that usually return to previous levels within 4-5 years. The Gulf of California does not show this sort of marked fluctuations but it is genetically isolated from the remaining geographic distribution (Maldonado et al. 1985; Schramm 2003, Bowen et al. 2005).

Increasing