Vagrant seals in Plettenberg Bay
Although the Cape Fur seal (Arctocephalus pusillus pusillus) is southern Africa’s only endemic pinniped species, we do get a number of vagrant pinniped species that visit our shores. In Plettenberg Bay, we see both Subantarctic fur seals (Arctocephalus tropicalis) and southern elephant seals (Mirounga leonina) on occasion. These species are vagrants from Antarctic and Subantarctic waters and visit our shores briefly during their travels at sea.
Subantarctic fur seals have been recorded from the South African coastline on over 20 occasions. These seals inhabit isolated islands situated north of the Antarctic Convergence such as Tristan da Cunha, Gough, Prince Edward, Marion and Crozet. They differ from our endemic Cape Fur seals in both size and appearance. They are considerably smaller than Cape Fur seals with males reaching 2 m in length and up to 165 kg in weight, while females only reach 1.4 m in length and 36 kg in weight. The species differs in appearance to Cape Fur seals by having pale yellowish-orange faces and chests. In June 2014, a juvenile female Subantarctic fur seal of roughly 2 years of age was found ashore in Plettenberg Bay. Later named Polly, she was transported to Bayworld in Port Elizabeth for rehabilitation, before being released about 60 km offshore with another Subantarctic fur seal named Bokkie.
A number of southern elephant seals come ashore along the South African coastline every year. These seals are widely distributed in the Southern Ocean and breed in southern Argentina as well as most cold temperate and subantarctic islands. The closest breeding colonies to South Africa are found on Prince Edward, Marion, Tristan da Cunha and Gough Islands. Southern elephant seals dwarf Cape Fur seals, with males reaching up to 6.5 m in length and weighing up to 3.7 tons. The species shows a high degree of sexual size dimorphism with females being much smaller than the males and only attaining a maximum length and weight of 4 m and 800 kg, respectively. Males of the species have a conspicuous proboscis, or nose, which can be inflated in order to create a resonating chamber when roaring at other bulls during fights. A young male southern elephant seal, named Solo, has been seen in Plettenberg Bay annually for the last few years. On 12 August he yet again showed up at Robberg Peninsula’s Cape Fur seal colony after being away for a period of a few months. Solo is believed to be about 7 to 9 years-of-age. At this age, male elephant seals are sexually mature, but they generally do not breed before the age of 10. In fact, due to the intense competition for mates between males of this species, most males never breed and only a few strong bulls will breed in more than one season. In 2012 and 2014, Solo was observed killing and feeding on Cape fur seal pups along Robberg Peninsula, a suprising behaviour never before documented for this species.
It is always exciting to see these visitors from afar along our coastline. However, these seals generally come ashore here to rest after travelling so far, or when they are sick or injured. If you happen to come across a seal ashore on the beach that looks sick or injured, please contact the Bayworld Stranding Response Network at 071 724 2122 or Plettenberg Bay’s local stranding coordinator Dr. Gwen Penry at 072 817 7979. Stranding response can only be carried out by authorities in possession of a permit and it is advised that the public do not attempt to capture, handle or touch seals as they can be very dangerous and deliver a nasty bite.
Written by Danielle Conry
For further reading:
- Shirihai, H. 2007. A complete guide to Antarctic wildlife: The birds and marine mammals of the Antarctic continent and the Southern Ocean. A&C Black Publishers, London.