Working together to mitigate the effects of rabies among Cape fur seals in the Western Cape

Cape fur seals are a ubiquitous presence along the coastline of South Africa, occurring in large colonies from Algoa Bay to Southern Angola. Not only do they play a valuable role in our unique marine ecosystems, but they are also a huge tourism drawcard.

Recently, Cape fur seals have been making the news for different reasons – an outbreak of rabies has put their populations and public safety in jeopardy. Thankfully, several incredible organisations are working to mitigate the effects of the outbreak.

Why is this happening?

At the request of Western Cape Vet Services, Onderstepoort Veterinary Research Institute conducted preliminary sequencing of rabies viruses found in the seals. Essentially, the rabies strains were analysed and interpreted. The results showed that the rabies viruses in seals are related to those maintained in wild animals in Southern Africa, indicating that seals were initially infected by another wild animal on land, and then rabies spread from seal to seal.

Despite ambiguity on its origin, several factors can clearly explain why the rabies outbreak spread so quickly. The first is that Cape fur seals are highly sociable animals, resting and often play-fighting in close proximity. They also have a wide range, travelling extended distances for foraging and towards the breeding season. Given that rabies is mainly transmitted through the saliva of an infected animal, experts strongly believe that the virus was transmitted through close physical contact and consequently spread through the populations.

This outbreak is believed to be among the first cases of rabies in a marine mammal. One of the only confirmed cases of pinniped (seal) rabies was described in a ringed seal in Norway in the early 1980s. According to the Two Oceans Aquarium’s Dr Ilse Jenkinson, no rabies vaccine trials have been conducted on any pinniped species to date, although extensive work has been done on other domestic/wildlife species from which the knowledge can be extrapolated. Based on the former, vaccine trials are underway to test the efficacy of the vaccine in these marine mammals.

What are we doing?

The Two Oceans Aquarium Foundation’s veterinary and marine wildlife staff have been working with members of the Department of Forestry, Fisheries, and Environment, SPCA, City of Cape Town, SharkSpotters, Sea Search, SAAMBR, and Western Cape Veterinary Services to mitigate the spread of rabies in the Western Cape.

Thus far, the prevailing theory is that rabies is now endemic in the Cape fur seal population. This means that our teams’ priorities lie in managing human safety and containing the spread of the virus.

Large-scale vaccination of Cape fur seals is not currently feasible due to limitations in vaccine administration and the difficulty of the animals’ geographic environment and movements. Therefore, the agreed-upon strategy was a targeted vaccination drive in a one-health approach. One-health is a collaborative, multisectoral, and transdisciplinary approach which works well in our South African context. Trained and permitted staff from the aforementioned organisations have been working together on vaccinating specific Cape fur seals that are believed to be more likely to encounter humans, pets, other seals, and marine mammals.

“By vaccinating the identified habituated seals in these specific areas, the potential risk of them contracting the disease will be greatly reduced. This will, in turn, reduce the risk of rabies transfer to members of the public making use of these areas,” says Dr Ilse Jenkinson, Two Oceans Aquarium.

Several high-risk areas along the Cape Peninsula have been identified where habituated Cape fur seals come into regular contact with humans. This includes tourists, harbour workers, and fishers. The habituation of seals in these areas is mainly attributed to the illegal “seal feeding”, where seals are enticed by food to attract tourists. “Where long-term efforts to control this illegal industry have failed, a stop-gap measure of vaccination is to be employed in the short-term for public safety,” says Dr Ilse Jenkinson.

During each of the vaccination procedures, the seal is tagged with a unique colour and code to make identification of individual animals easy, aiding in future booster vaccinations and long-term tracking of their behaviour and movements.

Buffel the elephant seal was included…

Buffel is a southern elephant seal who first appeared in Buffelsbaai in 2016. Then, it was a rare sighting – Buffel was tagged and expected to journey on to the Southern Ocean. However, in the years to follow, Buffel began to reappear on Duiker Island, Fish Hoek Beach, and around Cape Point. It was decided that he should be included in the vaccination drive mainly to reduce the risk of him contracting the disease and potentially being a vector to spread the virus to other ecosystems in the southern islands and other seal colonies.

What now?

While our teams are working hard to vaccinate high-risk seals, the usual guidelines regarding interaction with Cape fur seals remain relevant and of the utmost importance. Western Cape locals and visitors share their space with an incredible array of wildlife, and it is vital that we respect them. As with any wild animal, it is discouraged to approach Cape fur seals or intrude on their space, whether on the beach, in a harbour, or anywhere else.

If you notice abnormal behaviour or aggression in Cape fur seals or any other mammal, please report this to your local state veterinary office or the Two Oceans Aquarium Foundation.

Our teams continue to mitigate the effects of the rabies outbreak to the best of our ability – these stretch from the practical steps of vaccination to the broader messages of awareness. The study of rabies in marine mammals is still very new, so we are working on shedding as much light on the situation as possible.