Sea Shorts: The largest fur seal in the world

There are just 9 species of fur seals living on Earth today. All but one are found in the southern hemisphere, and all adorned in a thick underfur that gives them their name.

With the males reaching 2.3 meters in length and weighing in somewhere between 200 and 300 kg, the brown fur seal (Arctocephalus pusillus) is the largest fur seal on Earth. On land, their size and weight is apparent as they lumber slowly about. But in the water they become sleek, graceful, and fast moving.

Brown fur seals are fascinating, but something really interesting is where they set up home. Take a look at this distribution map. Notice anything odd? 

 Distribution of the Brown fur seal ( Arctocephalus pusillus)  (dark blue: breeding colonies; light blue: non-breeding individuals). Credit  Mirko Thiessen/Wikipedia  ( CC BY-SA 3.0 )

Distribution of the Brown fur seal (Arctocephalus pusillus) (dark blue: breeding colonies; light blue: non-breeding individuals). Credit Mirko Thiessen/Wikipedia (CC BY-SA 3.0)

Yep - the brown fur seal has a split distribution - some along the southwest coast of Africa, and some along the southeast coast of Australia... and nothing in the middle. 

It turns out that the brown fur seal species is actually two sub-species. The two groups can breed together, but because of the large distance between them, they don't- or at least not very much. So in Australia, we have the imaginatively named 'Australian fur seal' (Arctocephalus pusillus doriferus) and in Africa, the 'Cape' or 'South African' fur seal (Arctocephalus pusillus pusillus). Actually, if you look again at the map, you'll see that 'Cape' and 'South African' isn't very accurate. The seals also breed in Nambia, and some even go into Angola! 

 Brown fur seals near Bruny Island in Tasmania, Australia. Credit Samantha Andrews/Ocean Oculus

Brown fur seals near Bruny Island in Tasmania, Australia. Credit Samantha Andrews/Ocean Oculus

Thanks to genetic tests, we know that the two groups only became separated fairly recently. It seems that the Australian sub-species is younger than the South African one. It's thought that around 12,000 years 'before present' (which means before 1950), some of the fur seals took advantage of the "west wind drift" - otherwise known as the Antarctic Circumpolar Current to travel the vast distance between southwest Africa and eastern Australia. 

Unlike the New Zealand sea lion, these brown fur seals are doing quite well. Despite massive hunting in the 17, 18, and 19th centuries, both sub-species are seeing growth in numbers of individuals - and seem to be setting up new colonies