Galápagos Fur Seal
(Arctocephalus galapagoensis)
| Distribution and Numbers The Galápagos fur seal, smallest of the pinnipeds, is restricted to the Galápagos Islands off the coast of Ecuador and does not seem to share either territory or food supply with the other pinniped species in the islands, the Galápagos sea lion. The most recently evaluated survey in 1978 produced a population estimate of 40,000, but it is not known how many Galápagos fur seals there are currently, especially since the 1982-83 El Niño event which is thought to have halved the population. Status Thousands of Galápagos fur seals were killed by commercial sealers in the 19th century. They became a protected species under Ecuadorian legislation in the 1930s, but protection only really became effective after 1959 when most of the Galápagos Islands was declared a National Park. The waters around the islands are also protected, including a no-fishing zone, to a distance of 40 nautical miles. The species is listed as Vulnerable on the IUCN Red List and as an Appendix II species under CITES. |
 Photo: Phillip Colla, Phillip Colla Wildlife Photography |
| Because of the position of the Galápagos Islands, local marine food
supplies vary quite drastically due to El Niño events and mass starvation is a real
possibility during these events. During the 1982-1983 El Niño, for example, the
population lost almost all of the four youngest year classes (1980-1983) along with about
30% of adult females and non-territorial males and almost 100% of large territorial males.
There were reports of unusual distributions of Galápagos fur seals during the 1997-1998
El Niño event but monitoring of five small colonies during this period showed no signs of
starvation in the fur seals and it is thought that the event did not have a major effect
on the population. There has been some mortality due to entanglement in gill nets but this
problem seems to have been solved. Feral dogs that have been introduced onto the islands
have also killed and attacked Galápagos fur seals. However this problem has been
controlled by the Galápagos National Park Service. |
| Lifestyle With the longest pupping period of any fur seal, pups are born between mid-August and mid-November, most being born between late September and early October. The preferred breeding habitat is rocky shores with sea caves, and most breeding sites are on the western coasts of the islands. Females give birth 2-3 days after coming ashore. |
 Photo: Phillip Colla, Phillip Colla Wildlife Photography |
About one week after giving birth to her pup, the mother starts a cycle of alternately going to sea to feed for 1-4 days and then coming back ashore to nurse her pup for about 1 day. The duration of the nursing periods and the feeding trips appear to vary with the phase of the lunar month - mothers have been seen to spend 1.5-75 hours (median 22.5 hours) on shore feeding their pup and 3.5-127 hours (median 33.5 hours) feeding at sea. Observations have shown that the pups spend more time playing and moving around when their mother is away, although they have to take care since females can be quite ferocious towards pups that are not their own. The female mates about 8 days after giving birth. As with other fur seals the males maintain breeding territories, in this case for about 27 days at a time. The Galápagos fur seal has the longest nursing period of any seal, the pups finally being weaned between 1-2 years but sometimes even being nursed at the age of 3 years. Only the walrus has a nursing period close to this. The nursing period of a particular pup tends to be longer if food has been scarce during the time of its nursing, and the long period may therefore be a mechanism that the species has evolved to improve survival rates through such events as El Niños. |
| Pups begin to swim a little after a few months and start
to engage in some independent feeding at 9-12 months. They moult into their greyish-brown
adult fur at about 4 months. Galápagos fur seals do not migrate. They feed primarily on
fish and cephalopods, close to shore and exclusively at night when their prey migrates
closer to the surface. Sharks and killer whales are known to be predators but not to any
great extent. Statistics Adult males measure up to 1.5m long and weigh 64kg on average, while adult females are smaller, measuring an average of 1.2m in length and weighing from 22-34kg (average 28kg). Pups weigh 3-4.5kg at birth. Females reach sexual maturity at 3-4 years, while males do not attain territorial status until they are around 7-10 years of age. A maximum dive depth of 169m, lasting 6.5 minutes, has been recorded for an adult female. |
 Photo: Phillip Colla, Phillip Colla Wildlife Photography |
|
 |