Zalophus californianus are found along the shore from California to Mexico including Baja and Tres Marias Islands, in the Galapagos Islands and in the southern Sea of Japan (Scheffer, 1958). The populations in each area do not interact with other populations (Scheffer, 1958) and therefore are considered subspecies. California sea lions tend to seasonally migrate long distances (Riedman, 1990). Males usually migrate north to British Columbia after the breeding season (Mate, 1978).