California sea lion (Zalophus californianus, Lesson 1828)

The California sea lion is distributed from British Columbia, Canada, to the Islas Marías and Gulf of California, Mexico. The population is divided into five subpopulations: one each on the Pacific coasts of the United States and Baja California, Mexico, and three within the Gulf of California, Mexico. The California sea lion has a polygynous lek reproductive system; the breeding season occurs during the summer (May-August). Females give birth to one pup per season, and the lactation period can last from 11 months up to a year or more, with females alternating feeding trips at sea with short stays on land to nurse their young. Adult females have higher survival rates than their male counterparts. The current total population is 327,157-334,205 individuals, with 80% in the United States, 14% on the Pacific coast of Baja California, and 6% in the Gulf of California, Mexico. The US subpopulation has increased rapidly; in contrast, the four subpopulations in Mexico are at risk of disappearing. California sea lions are regularly impacted by warming events like El Niño that affect prey availability around their rookeries, as bycatch in fishing nets, and through illegal extraction presumably for their genitals.