Sub-Antarctic Fur Seals (Arctocephalus Tropicalis) can be found in the southern Indian and Atlantic Oceans. They were first described in 1872 from a specimen that was recovered in northern Australia, hence the inappropriate “Tropicalis” classification. Males, which can weigh around 3 times more than females, have a characteristic crest on their heads which stands up when they are excited. They can be further identified by the pale colouring on their faces which tends to form a “mask.” The colouring of adult sub-antarctic fur seals tends to be dark grey on the dorsal side with a yellowish cream on their chests.
Females of this species reach sexual maturity between 4-6 years while males take a little longer. As with the Northern Fur Seal, males only get territorial status when they are around 10 years old and are large enough to defend their turf by fighting and vocalizing. Their harems consist of between 4 and 12 females.
Pups weigh approximately 4kg at birth and are born with a black coat which begins to moult when they are 3 months old. Their mothers will mate around ten days after giving birth to her pup and will remain with them for a week or so, before hunger sends her off on foraging excursions. These excursions to sea will last up to 5 days before she will return to nurse and suckle for another 2 or 3 days. Pups of this species take around 9 months to wean.
Adult males weigh in at around 160kg and will reach sexual maturity when they are between 4-8 years. They will only manage to get territorial status once they are around 10 years. Females are much smaller, weighing in at +- 50kgs. Females reach sexual maturity when they are between 4-6 years.
Lactating mothers, whose milk has a 40% fat content, have been known to travel over 500km from the breeding grounds while on their foraging excursions!
Research has shown that inter species breeding between Sub-Antarctic Fur Seals and Antarctic Fur Seals takes place where breeding grounds over-lap, such as Marion and Macquarie Islands.
There are several collective terms for seals. They can be a hurd, a bob, a crash, a team, a pod, a rookery, a harem or a colony of seals.
During the 1800’s, the species was hunted to the brink of extinction for their fur. They are listed on Appendix II of CITES and are protected under several pieces of legislation.
Sub-Antarctic Fur Seals on Marion Island tend to be smaller than the rest of the population. The reason for this is unknown, though it is suspected that a lower amount of food availability could be the cause.