The Galapagos Fur Seal (Arctocephalus galapagoensis) is found in the Galápagos Islands. It has a strong closeness to the South American Fur Seal (Arctocephalus australis) but is presently categorised under its own species. ‘Arctocephalus’ as before, describes its ‘bear-like’ head. Following severe declines in numbers and a general downward trend, the species is classified as Endangered. Estimated population size = 15,000.
A. galapagoensis are the smallest of the fur seals (males ♂ up to 1.6 m long/ 70 kg, females ♀ up to 1.3 m/ 40 kg). They are still sexually dimorphic, but less so than other otariids. They have relatively compact bodies, though the males are still thick and heavy. Fore flippers are long and broad, while hind flippers are relatively short, and the males have a slight mane on their necks. The head is somewhat small, with a snub, quite pointy muzzle, and small features including eyes and nose. White whiskers are short and thick. Males are largely dark brown in colour, of various shades, while females tend to be paler and grey-brown, maybe even a rusty colour underneath.
A. galapagoensis forage during the night, diving on average 20-30 metres down in the open ocean.They eat a variety of squid, as well as some deep-sea fishes such as lanternfish and smelt, which migrate up from the depths at night time to feed.
Sexual maturity – males ♂ 4-6 years old/ females ♀ 4-6 years old.
Breeding occurs from August to November, and with a polygynous structure, the early-arriving males hold large territories which the females select from to birth their young, the peak of which takes place in September and October. Mating occurs on land and gestation lasts approximately a year, with a period of delayed implantation. The pups are born with brown-black fur and will keep this for the first 4-6 months of life. For a week the mother suckles her young, before venturing to sea on short foraging missions, returning every few days to nurse. A. galapagoensis has a very long weaning period, which frequently lasts for 18 months, and may even run into several years. In fact, a second pup is often born before the first is weaned, and in this case there is competition between the two for milk. Sadly this will often result in aggression towards the youngest pup, as well as a high chance of starvation, as the stronger yearling refuses to allow its sibling near the teats. In years with good resources however, both may survive. An adult moult follows breeding. Life expectancy for the species is approximately 20 years.