Galápagos sea lion
The Galápagos sea lion (Zalophus wollebaeki) is a species of sea lion that lives and breeds on the Galápagos Islands and, in smaller numbers, on Isla de la Plata (Ecuador). Being fairly social, they are often spotted sun-bathing on sandy shores or rock groups, or gliding through the surf. They are the smallest sea lion species.
Taxonomy[edit]
This species was first described by E. Sivertsen in 1953. It has been considered a subspecies of Zalophus californianus (called Z. c. wollebaeki) by many authors. But recent genetic data supports Z. wollebaeki as a separate species.[1] The species belongs to the family Otariidae and genus Zalophus.
Distribution[edit]
Galápagos sea lions can be found on all of the islands of the Galápagos archipelago. Less than a quarter of them reside on San Cristobal Island. They have also colonized Isla de la Plata, just offshore mainland Ecuador, and can be spotted from the Ecuadorian coast north to Isla Gorgona in Colombia. Records have also been made of sightings on Isla del Coco, which is about 500 km southwest of Costa Rica. The population on Isla del Coco is considered vagrant.[1][6]
Threats and status[edit]
The majority of the Galápagos population is protected, as the islands are a part of an Ecuadorian national park surrounded by a marine resources reserve. Although the Galápagos Islands are a popular tourist destination, strict rules exist to protect all wildlife from disturbance. Fluctuating between 20,000 and 50,000 sea lions, the population does have a few threats. During el Niño events, the population tends to decrease as ocean temperatures warm and cold-adapted marine life on which the sea lions depend declines, which lead to die-offs or cessation of reproduction. Sharks and killer whales are the main predators of the sea lion. Although adult sea lions have less to worry about, pups are easy targets. Regulations governing human behavior help mitigate risks to sea lions due to human contact, but as the human population continues to grow it nevertheless presents risks of accident and disease.[6] The sea lions have learned that being near the fisheries they have a better chance at capturing fish with little to no work, but as a result they are in more danger from boats and net entanglement.[6] They are impacted by humans indirectly as well. Stray dogs introduced by humans form packs and attack sea lions.[6] The pesticide DDT, still in targeted use to prevent malaria in tropical countries, accumulates through the food chain and is found at near-toxic concentrations in sea lion pups.[13] From 2008 through 2012, death by disease increased.[6] Galapagos Sea lions are known to be susceptible to canine distemper virus, however this disease is not believed to be endemic among the population.[14]