Subantarctic fur seals are medium in size animals which are recognized by their characteristic “face mask”. Both sexes have distinctive, creamy-orange chests and faces. Their bellies are more brownish. Males have a dark grey to black back. The females are lighter grey in color. Pups are black at birth, but most at about 3 months old. Subantarctic fur seals have a short and flat snout and short but broad flippers.
Subantarctic fur seals are found in the southern parts of the Indian, Pacific, and Atlantic Oceans. The largest breeding colonies are on Gough Island in the South Atlantic and Île Amsterdam in the southern part of the Indian Ocean. Breeding grounds are also found at Marion Island in the Prince Edward Islands, the Crozet Islands, and Macquarie Island. During the breeding season, Subantarctic fur seals spend time on rocky shores or boulder beaches.
Subantarctic fur seals are social creatures that live in colonies. Females spend most of their time with pups. They usually leave only for hunting and then come back to nurse their young. Males spend most of the year at sea or at colonies with other males, returning to breeding territories in early summer to mate. When on land outside of the mating season, males are not very active. The activity pattern of non-breeding males depends on environmental temperatures. When the temperature is under 18.5 degrees Celsius, males are nocturnal. They hunt in the evening and return on land in the late morning. However, when the temperature gets higher, they become diurnal. They leave the land at hot midday, cooling themselves in the water, and return in the evening to rest. This species uses vocal, visual, and tactile communication. Females mainly communicate with their pups, using a specific call as well as smell to establish the bond. Each pup as well as a unique call by which it is recognized by the mother. Males use calls and visual displays while competing for breeding territories and interact with females, when threatened or during physical fights.
Subantarctic fur seals have a polygynous mating system in which males defend territories with a harem of 6-20 females. They defend these territories through fighting, vocalizations, and bluff. The breeding season takes place from November to January. Females give birth to a single pup after a gestation period that lasts around 51 weeks. After 8 to 12 days after giving birth females mate again. Weaning occurs when pups are 11 months old, shortly before the next offspring is born. Before weaning, little seals stay at the rookery. They spend time on land and in the water. Males in this species are ready to mate at 3 to 4 years of age, but full maturity is attained at 10 to 11 years when they are able to hold a harem. Females become reproductively mature when they are 5 years old.
Subantarctic fur seals have been hunted almost to extinction in the 19th century for its fur. Today, these animals suffer from climate change, entanglement in debris created by humans (polypropylene straps, fishing nets, nylon string) and infectious diseases.
According to the IUCN Red List, the total population size of Subantarctic fur seals was over 400,000 individuals in the early 2000s. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
Subantarctic fur seals are key predators of myctophid fish and other species of fish and squid. They are also important prey item for sharks and orcas.