Occasional presence of a California sea lion at Isla Roca Partida, Revillagigedo Archipelago, México

Resumen

Introduction: California sea lions (Zalophus californianus) are a wide ranging species in the Northeastern coast of the United States and Mexico; the former limits of the species southern distribution were the Islas Marias Archipelago. Since the 1980’s several individuals have been sighted outside of their range, as far north as Alaska in the U. S. A., and as far south as Chiapas in Mexico. Individuals of the species move between islands in their reproductive colonies; there are multiple records of individuals of several age classes outside of their southern limit, including a neonate in Manzanillo, Colima.Results: We report the first record of a subadult male in the waters of Roca Partida (18° 59’ 41†N, -112° 04’ 07†W), Revillagigedo Archipelago on November 29, 2014. The individual stayed for three weeks in the area.Discussion and conclusions: The observation took place in El Niño type conditions, in which Pacific surface water temperature increased from 1 to 1.5 °C above normal. This event may have caused this individual sea lion to move far away from the continental coast in search for prey. This sea lion showed a good body condition. Roca Partida, is more than 650 km southwest of a former colony of sea lions on Islas Marías, and 600 km from the nearest reproductive colony at Isla Santa Margarita, Baja California Sur, this record shows the far away and occasional ranging of California sea lions outside their coastal - continental distribution.