Experts tackle Cape fur seal aggression and rabies outbreak

• The City of Cape Town, in collaboration with various organisations, held a workshop to address the recent increase in aggressive seal behaviour along the Western Cape coast.
• The rabies virus, now confirmed in Cape fur seals, is a primary concern, prompting the need for ongoing management and research.
• Despite some groups pointing to pollution, the City has focused on the confirmed rabies cases as the cause.

As seals continue to wash ashore on Bloubergstrand, Sunset Beach and Milnerton Beach, and attack surfers who now fear the waves, a two-day workshop was recently held to address the issue. 

The City of Cape Town in partnership with the Department of Forestry, Fisheries and the Environment (DFFE), the Two Oceans Aquarium Foundation and Sea Search, partnered on an expert scientific workshop. Some key findings, outcomes and agreements have been concluded, the City told TygerBurger. 

TygerBurger reported on the recent rabies outbreak noted in seals (“Rabies detected in Cape Fur seals along Western Cape coast, warning issued”, 5 July) after a Cape fur seal off the coast at Big Bay tested positive for rabies. It died on 22 May and the laboratory results came in on 7 June.

The workshop focused on investigating the possible causes of the increase in the frequency of unusual and unprovoked Cape Fur Seal bites and aggression on recreational users in the Western Cape. 

ALSO READ | Rabies alert: Dead seals cause alarm on Cape Town’s popular beaches

With the recent confirmation of rabies in the Cape fur seal population, it included discussions on the implications of and appropriate management responses to the rabies virus in the Cape fur seal population.

However, one group, Water Quality Awareness, said the City of Cape Town’s report denies any link to pollution as a cause or its impact on seals. 

“Let call this the ‘Pinocchio Effect’ in a sustained narrative that denies the truth in the ‘absence’ of data showing otherwise,” it said. 

On Monday an environmentalist told TygerBurger pollution making its way in the ocean should also be considered in the report. 

According to Sea Search Research and Conservation 17 seals have tested positive for the virus so far. Last month, a single seal bit several surfers in a matter of minutes at Muizeberg Beach. These attacks convinced authorities to euthanise four animals and send their bodies to be tested for rabies.

Findings

The Cape Fur Seal population is stable at around 2 million and annual changes in population numbers fluctuate by only 1% to 2%.

Marine mammal experts, veterinarians, marine scientists, various government departments and key stakeholders from South Africa and around the world attended the two-day workshop .

READ | Rabies detected in Cape Fur seals along Western Cape coast, warning issued 

“Some levels of aggression in seals should be considered normal and may arise from various causes including territorial behaviour, maternal protectiveness, pain or distress, as well as from poor health condition caused by various disease states,” the City said. “However, excessive aggression associated with unusual behaviour that is being documented in multiple cases is not normal and is linked directly to the now confirmed presence of the rabies virus in some individual Cape Fur Seals.”

The workshop also concluded that rabies appears to be well-established in the Cape Fur Seal population and is unlikely to be eradicable and should now be considered endemic requiring ongoing and long-term management by coastal authorities.

“Initial indications are that rabies was transmitted to seals from another wildlife population and not from local domestic dogs,” the City said.

What does it mean for seals

The effect on the seal population remains unknown, but in other animals rabies typically pursues a ‘slow burn’ course of flares and declines, rather than resulting in mass mortalities. Questions however remain about the differences between seals – highly gregarious animals living in very large colonies – and other terrestrial animals in which rabies occurs. 

“Given that this is the first documented rabies infection in a marine mammal population there are many unknowns.”

Coastal authorities in partnership with the State Vet, veterinary experts, researchers, marine mammal experts and animal welfare organisations will need to continue to implement ongoing proactive measures to manage the rabies outbreak responsibly, the department noted at the workshop.

Actions

These ongoing management actions include: 

• Reporting: As a controlled disease, all suspected or confirmed rabies cases must be reported to the relevant state veterinarian.
• Ongoing surveillance of the seal colony: The continual surveillance of seal colonies and seals that come ashore against a clear Case Definition through organised patrols and via a network of coastal users. 
• Euthanasia is a justified response: A definitive diagnosis of rabies can only be done post-mortem. As such, in cases where the presentation includes unprovoked or extreme aggression a poor prognosis is likely irrespective of the cause. 
• Euthanasia responsibility: Only officially permitted government authorities and recognised institutions such as the Cape of Good Hope SPCA and others may humanely euthanise seals that meet the rabies case definition. Importantly, it is illegal for any member of the public to harm or kill any Cape Fur Seal regardless of its rabies status. 
• Research partners: Long-term surveillance is necessary for understanding the disease prevalence and impact. An appropriate research programme will be established with research organisations.Vaccination of seals: With more than 2 million Cape Fur Seals spread between Southern Angola and the Eastern Cape, vaccination of the wild population is not considered viable or possible. 
• Vaccination may be valuable in some seals: Although efficacy of rabies vaccines in seals is not yet known, there is no reason to expect adverse outcomes and it was strongly recommended that vaccination be trialled with a focus on animals that come into regular contact with humans. This would include harbour-associated seals and rehabilitation centre seals. The Two Oceans Aquarium will develop a standard procedure for vaccinating seals, including dosage and injection options. Vaccinated seals should be tagged to allow repeat identification and follow up vaccination.
• Vagrant seals: Visiting elephant seals and Sub-Antarctic fur seals will be vaccinated as a precautionary measure even while efforts are under way to establish efficacy of the vaccine in seals as a responsible precautionary measure to reduce the small risk of rabies spreading to the Sub-Antarctic and the southern ocean regions. Vaccinated seals will be tagged where possible to allow repeat identification.
• Rabies testing: Only seals that are involved in a confirmed bite on a person or domestic dog will and must be euthanised immediately, and sent for testing for rabies by the State Vet.
• Public Health Advisory: The public health advisory remains that rabies vaccines are not recommended for the general public at this time and that anyone bitten or scratched by a seal resulting in an open wound must seek immediate medical attention and receive Post Exposure Prophylaxis.
• Domestic Dogs: Dogs’ rabies vaccines must be up to date at all times. The public is also reminded that is their individual responsibility to avoid their dogs having contact with seals at all times.
• Public communication: Ongoing updates on the rabies outbreak in Cape Fur Seals will be provided. Only results provided by the State Vet should be considered confirmed and factual.
• Seal Feeders: Seal feeding as done at Hout Bay harbour is illegal, as is the aiding and abetting any seal feeders through paying or participating, which includes photographing – these are offences and offenders may be arrested.