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Outcome of Expert Cape Fur Seal workshop on unprovoked seal aggression

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, convened an expert scientific workshop last week. Some key findings, outcomes, and agreements have been concluded.

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. With the recent confirmation of rabies in the Cape Fur Seal population, the workshop included discussions about the implications of and appropriate management responses to the rabies virus in the Cape Fur Seal population. Marine mammal experts, veterinarians, marine scientists, various government departments and key stakeholders from South Africa and around the world attended the two-day workshop held in Cape Town from 23 July to 24 July 2024 at the Two Oceans Aquarium.The key findings, outcomes, and agreements are as follows:Causes of aggression: 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. However, excessive aggression associated with unusual behaviour that is being documented in multiple cases is not normal and is directly linked to the now confirmed presence of the rabies virus in some individual Cape Fur Seals.Eradication unlikely: 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. Source:Initial indications are that rabies was transmitted to seals from another wildlife population and not from local domestic dogs. What it means 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. Proactive measures: 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.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. Given the high risk posed by a potentially rabid individual that meets the Case Definition, immediate euthanasia of the affected animal is a justified and necessary response, in the interest of the seal itself, the seal population and as a protective measure for people.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 over 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. What to do: The public is again advised to stay clear of all coastal wildlife including seals regardless of their rabies status. It is illegal to approach, touch, handle, harass or interfere with any coastal wildlife. Seals are a healthy and normal part of our coastline and you should expect to see and encounter seals along our beaches and inshore areas. Those who come across a seal that is behaving unusually or aggressively, are advised as follows:Move away from the animal or leave the water if they are surfing, swimming or diving. Immediately inform the relevant authorities:<ul><ul><li>Cape Town – City of Cape Town on 021 480 7700, Cape of Good Hope SPCA on 021 700 4140</li><li>West Coast – CapeNature on 083 236 2924</li><li>Overberg – CapeNature on 083 236 2924</li><li>Southern Cape – Plett Stranding Hotline on 079 463 4837 and CapeNature on 044 5332125</li><li>Eastern Cape - Bay World Stranding Hotline – 071 724 2122 </li><li>Table Mountain National Park on 021 783 0234 Other key findings and outcomes from the expert workshop:</li></ul><ul><li>The Cape Fur Seal population is stable at around 2 million and annual changes in population numbers fluctuate by only 1% to 2%. There is a small eastward movement of the population with some new colonies forming, but the bulk of the seals remain on the West Coast of South Africa and Namibia in very large colonies </li><li>It is unlikely that Domoic Acid, which is a natural by-product of some phytoplankton species, is having a similar marine species impact as that which has been documented in California as the levels of DA in our waters are over 100 fold lower than measured in California. While present and having been detected in some seal necropsies, the concentrations found are not likely to be causing the unusual aggressive behaviour documented in the last three years</li><li>There are multiple disease processes occurring in the seal population and individual seals at any given time, as is the case in all wildlife populations</li><li>Changes in predator populations, particularly the absence of Great White Sharks in the Western Cape, does not explain the unusually aggressive behaviour of seals observed over the past three years. However, these changes might be linked to other ecological shifts, such as seals moving to new areas, being present at different times, or changing their survival or hunting behaviours.</li><li>It is not likely that marine pollution is a contributor to the recent incidents and measured pollution levels in Cape Town including Chemicals of Emerging Concern do not differ from those levels measured anywhere else globally along all shorelines. End</li></ul></ul>

2024-07-30T22:00:00Z

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