The Sub-Antarctic Fur Seal (Arctocephalus tropicalis) breeds on sub-antarctic islands including Macquarie Island and Heard Island. It is estimated that there are approximately 300,000 Sub-antarctic Fur Seals occuring throughout the sub-antartic region. This species occasionaly occurs in Australian waters at Australian Fur Seal colonies in the Bass Strait off Tasmania. It is difficult to distinguish this species from the Australian and New Zealand fur seals that may venture into Tasmanian waters. The females are very similar in apperance to the Antarctic Fur Seal however the males can be told apart by a black crest on their head and a pale belly of the Sub-Antarctic compared to the more uniform grey-brown of the Antarctic Fur Seal. They also favour different breeding sites, although some hybridisation occurs in mixed colonies such as on Macquarie Island.
Research on the Sub-Antarctic Fur Seal on Macquarie Island has found that the species does most of its hunting at night for pelagic fish species and dives mostly to shallow depths. It may also prey on penguins as well.