The Galápagos fur seal (Arctocephalus galapagoensis) is one of eight seals in the genus Arctocephalus. It is the smallest of all eared seals. It is endemic to the Galápagos Islands in the eastern Pacific. The total estimated population as of 1970 was said to be about 30,000, although the population has been said to be on the decline since the 1980s due to environmental factors such as pollution, disease, invasive species, and their limited territory. Due to the population having been historically vulnerable to hunting, the Galápagos fur seal has been protected by the Ecuadorian government since 1934. They also have large eyes which allow them to hunt at night. The Galápagos fur seals look very similar to the Galápagos sea lions so it is important to note some of their differences.
Range and habitat
thumb|Galápagos fur seals found on rock ledges and crevices
The Galápagos fur seal is endemic to the Galapagos Islands in Ecuador, South America. It is present on nearly all the islands of the Galapagos. They are typically found close to the coastline where there are rock ledges and crevices that they can find shade in, in such a warm climate. It is classified as a non-migrant species. Females that are lactating do not travel long distances and tend to stay within the colony and only have moderately brief outings when they do venture out. However, recent research has documented the presence of Galápagos fur seals in Mexico
Reproduction
Galápagos fur seals live in large colonies on the rocky beaches of the Galápagos Islands. These colonies are then divided into territories by the male seals during breeding season, which is mid-August to mid-November, with a peak in late September and early October. Each successful reproductive female will choose a territory on the beach to pup on.
thumb|Galápagos fur seal pup
Maternal care
Galápagos fur seals have the lowest reproductive rate reported in seals, and it takes an unusually long time to raise seal pups to independence. Females bear only one pup at a time, and she remains with her newborn for a week before leaving to feed. She then periodically returns to the pup and stays to suckle it for a few days before leaving on another hunting trip. Females recognize their own pups by smell and sound, and pups also learn to identify their mothers by the females' "pup attraction calls".
Interbrood conflict
Fur seal pups rely on their mother's milk for the first eighteen months, and weaning may be delayed for up to two or three years if conditions are poor. The result is that every year up to 23% of pups are born when an older sibling is still suckling. Survival of the younger sibling greatly depends on the availability of resources. In years when there is abundant food, the mortality rate of second pups is as low as 5%, which is equivalent to the mortality rate of pups without siblings. In years when food is scarce, 80% of pups with suckling older siblings die within a month.
During periods when there is very little prey, interbrood conflict increases. Galápagos fur seal population is drastically affected by El Niño, a period accompanied by high water temperatures and a deepening thermocline. Food becomes scarce during El Niño, and thus older seals exhibit an intense aversion to weaning, causing the mother seal to neglect the younger sibling.
Male competition
Males will compete for the females when they become large enough by establishing territories on the beaches. The beaches are valuable pupping substrate for females. They have territories that average . During normal years, food is relatively plentiful. However, during an El Niño year, there can be fierce competition for food, and many young pups die during these years. The adult seals feed themselves before their young and during particularly rough El Niño years, most of the young seal populations will die.
The Galápagos fur seal has virtually no constant predators. Occasionally, sharks and orcas have been seen feeding on the seals, but this is very rare. Sharks and orcas are the main predator of most other seal species, but their migration paths do not usually pass the Galápagos.
Conservation
Anthropogenic Threats
The Galápagos Islands are heavily trafficked by tourists. However, tourism is well regulated and restricted by the Ecuadorian government. Collisions with boats which frequent the waters near the islands could also be fatal to the Galapagos fur seals. Historically, the Galápagos fur seal has also been threatened by hunting and invasive species. Whalers and sealers used to hunt the seals for their fur. The threat of hunting has been removed since the declaration of the Galápagos islands as a national park and the protection of the species under law. It is also important to note that the Galápagos Islands was one of the first places to be identified as a Natural World Heritage Site which helps preserve the island even more. Galápagos fur seals continue to face threats to their population due to their limited distribution across the islands of the Archipelago.