Are White sharks disappearing in South Africa?
The Mystery Surrounding White Shark ‘Disappearance’ in South Africa.
Various media reports have created much confusion to the public about white shark absence or disappearance in South Africa. Marine Dynamics has been monitoring white sharks since 2005 and hopes to shed some light on sightings for the past few years.
It is important to note that there are three areas that white shark cage diving operations occur thus this is where shark presence and absence is monitored. These areas are often confused in media reports.
Shark cage diving provides critical monitoring of this species in South Africa and this information is provided to the government every month – that is Department of Environment, Forestry and Fisheries – the department that provides cage diving permits. White sharks are highly migratory and move along the entire South African coastline. The shark ‘disappearance’ noted was first documented in 2017 post the arrival of two orca, known as Port and Starboard, who predated on white sharks primarily for their nutrient-rich liver. This hunting behaviour by these two had first been seen on seven gill sharks in False Bay but this was the first time that carcasses of white sharks were found and could be necropsied to confirm the cause of death. This hunting behaviour has been seen elsewhere in the world but was the first documented for South Africa, but only because the carcasses washed up. They may have killed others not accounted for. There was a flight response and the white sharks moved out of the area. They stayed away for longer periods of time so sightings for shark cage dive operators became less predictable. Prior to this disappearance, we had very few days that one would not see a white shark in what is one of the most accessible populations in the world, also one of the most affordable to cage dive in, and family-friendly as it requires no scuba and is just a breath-hold.
Note though that when reports came out a couple of years after initial predation, that there were no white sharks in False Bay, we were at that time seeing them in Gansbaai. They also seemed to shift eastwards and Mossel Bay reported decent sightings. However, when the orca were in that area, the sharks once again left.
Besides a flight response, white sharks face many threats such as shark nets and drumlines in Kwazulu Natal, accidental bycatch, impacts on their food sources based on various fishing industries. South Africa was the first country to protect the white shark, back in 1991, however, these factors have meant we have not seen a recovery in their numbers due to these various impacts and based on our own Gansbaai population study and in collaboration with shark scientists in South Africa, we do not believe there is an increasing trend. A PhD study at the University of Cape Town to which we have contributed data is preparing a comprehensive estimate combining multiple data sets of past and present research on white sharks.
Shark cage diving in Gansbaai attracts thousands of visitors every year and through concerted educational marketing efforts on white shark behaviour, the possibility of still seeing one, as well as the presence of bronze whaler sharks being recorded visiting the boats, the shark cage diving operators were able to sustain their business. The bronze whaler is a shark that is commercially fished and had only been recorded a few times before at the boat, and is also not often seen by most people so has actually been very popular with shark cage divers with some glowing reviews on the experience with this species.
The white sharks have not followed their usual seasonal hunting behaviour around the Geyser Rock seal colony. This hunting we believe does affect the way the Cape fur seals behave - as previously explored in one of our scientific publications - Cape fur seals are also known to opportunistically predate on the endangered African penguin, purely for their stomach contents. This can have a further devastating impact on the penguin population of Dyer Island opposite Geyser Rock. The white shark is a key apex predator that provides balance in the ecosystem.
The only consistent monitoring of white sharks is done by the daily observations on cage diving trips. Research of white sharks is also facilitated by this industry. Marine Dynamics and the Dyer Island Conservation Trust have done extensive work and published numerous scientific publications on white shark behaviour and movements, population, wound healing, all to impact conservation policy of this species. See the list of publications here. Shark biologist, Alison Towner, has contributed to two global collaborative papers on the future research priorities for white sharks and the impact of fishing on sharks.
We are greatly concerned about the future of all sharks in South Africa and have driven petitions around shark demersal longliners that are decimating some populations, have been outspoken about shark nets, and more positively have collaborated with other scientists to better understand and protect our white sharks.
Shark cage diving has further impacted the community as the value chain for this type of tourism is vast and much of Gansbaai and the Overstrand is affected by this. This includes employment, hotels and guest houses, restaurants, food and beverage purchases, transport, local business support, conservation projects, community education, and more.
We never take any species for granted. We work with the Marine Big 5 – whales, sharks, seals, dolphins and the endangered African penguin – and all face many challenges mostly created by humans. Marine Dynamics together with the Dyer Island Conservation Trust has been researching and conserving this area since 2000 with two decades of knowledge used to drive conservation policy. A key project is also the conservation of the African penguin with a dedicated African Penguin and Seabird Sanctuary. Marine pollution efforts include beach clean-up, fishing line bins, and storm drain catchment nets. There is also a priority placed on community education. You can read more about our work at www.dict.org.za