In honour of Shark Awareness Day on July 14, Earth.Org is looking at the disappearance of Great White Sharks off the coast of Cape Town, South Africa, a city known as the ‘great white capital of the world’. Many theories attempt to explain the dwindling populations of great white sharks, from orcas driving them away to unregulated fisheries, but the fact remains that the disappearance of great white sharks has ramifications beyond biodiversity loss: it threatens the ecotourism industry in the country, putting hundreds of jobs and billions of dollars at risk.
In 2017, cage-diving operators started reporting a sudden decline in sightings of great white sharks around False Bay and Gansbaai. From 2010 to 2016, great white sharks were sighted in False Bay an average of 205 times per year, according to conversation and research organisation Shark Spotters. In 2018, the sharks were spotted 50 times; in 2019, nothing. In January 2020, the first great white shark in 20 months was seen in False Bay.
Gregg Oelofse, head of coastal management for Cape Town, says that the disappearance of great white sharks could be the most dramatic environmental change he has seen in 20 years as a conservation biologist in the area, and adds that the loss of these sharks would be ‘massive’ for the city. “They are such a big part of the environment, of our sense of place and identity here, it would be a tragedy if they never came back,” he says.
As well as providing vital ocean ecosystem services, great white sharks are important for the tourism industry in South Africa. Along with Cape Town’s vineyards, game reserves and Table Mountain, the shark industry brings in USD$2.5bn a year for the country and employs hundreds of people. Tour companies take visitors out in boats to view the sharks, or lower them in cages into the sea, but the lack of sightings is a challenge to what is known as a successful ecotourism industry.
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What is Causing this Decline?
It’s unclear how many white sharks there are around South Africa- estimates have ranged from 500 to 900. The reason for this decline in great white sharks is not exactly clear. Some have suggested that the arrival in 2015 of orcas, another apex predator that attacks sharks, forced them to find other waters. Carcasses of great whites have been found with evidence that they were killed by orcas. There is also a lack of reliable data around how many great white sharks there are in the world.
Until 2019, it was believed that there were only two orcas thought to be having an impact on the great white shark population. Then, at the end of that year, a totally different pod came into Mossel Bay. Overnight, the Bay went from having seven to 10 different white sharks to having nothing.
Research shows that great whites are not genetically diverse enough to cope with new threats, which include pollution- such as heavy metals entering the food chain- and the impact of longline fishing boats that have taken vast numbers of fish from False Bay in recent years. Research has shown the sharks to be a single population, moving from site to site and breeding with each other. In a study from 2009 to 2011, it was estimated that there were around 300 breeders in the population, but the minimum to avoid inbreeding is around 500.
While great white sharks have been protected since 1991 in South Africa, other shark species that provide them with much of their diet are not. Chris Fallows, a shark expert and guide based in Cape Town, agrees that longline fishing is responsible for their disappearance, saying that the populations of the two species that provide much of the food of the great whites had collapsed.
“If you stopped the demersal shark longlining then there is every chance they will come back, but not in a hurry. The marine ecosystem has been intact for millions of years and in the space of five we have laid it to waste,” he says.
Further, sharks are very slow to reproduce which, when combined with these other factors, place further strain on their populations.
Who is Regulating the Problem?
South Africa’s fisheries are largely regulated by the Department of Agriculture, Forestry and Fisheries (DAFF), which gathers data on fish catches and populations and grants fishing rights to individuals and companies that conform to certain requirements. DAFF scientists analyse data to make catch size recommendations for different species, but DAFF managers (many of whom are not scientists) determine who gets fishing permits, the considerations of which are often political. The government encourages poorly regulated fisheries and has granted license to politically connected boat owners, whose catch is often sold to Australia, where it ends up as fish ‘n chips.
Since 2013, about three to six demersal longliners- fishing boats that set lines with up to 2 000 baited hooks on or near the sea floor- have been working hundreds of kilometres off the southern coast of South Africa. These boats have intensified their efforts in recent years, which may have starved juvenile great whites and driven others elsewhere.
In 2014, the government launched Operation Phakisa, in an effort to ‘grow the ocean economy’ and reduce unemployment in the country. The department has been mired with allegations of corruption for years- a 2014 investigation found that at least three participants in the demersal shark longline fishery had obtained fishing rights without having the correct shark-fishing boats.
The longline fisheries target small sharks that are important prey for juvenile white sharks. There are currently no limits in place to prevent the overfishing of these sharks, including soupfins and common smooth-hounds. The monitoring of South Africa’s coastlines is weak and some boats still fish in no-take zones of marine protected areas.
Shark nets and drumlines (baited hooks specifically targeting sharks) are also threatening sharks; the province of KwaZulu Natal uses these hooks to cull white sharks to prevent them from swimming close to the shore; between 2013 and 2017, nearly 17 white sharks died on these drumlines each year.
The DAFF has appointed an expert panel to ‘recommend actions needed to properly manage and conserve all shark species found along the country’s coasts, and to guide their long-term sustainable use’.
Uncertainties Amid COVID-19
With tourism in the country- even domestic- at a halt as a result of strict lockdown measures, there will be a gap in data about white sharks, since researchers are currently not allowed out to sea. Further, NGOs working to conserve sharks rely heavily on funding from tourism.
Researchers warn that this gap will mean incomplete and faulty data about great whites in the region, which may affect conservation efforts.
Moving forward, the South African government should increase monitoring activities of shark populations. A sensitive wildlife monitoring technique would be applicable. It utilises dynamic robotics equipped with sensors and wireless communication software. These robots can communicate and relay population size and density through sonar sensors, remotely and in real time. With such technology, onshore handlers can regularly update fishing boats on where to fish without the risk of extensive damage. Additionally, monitors can relay the timely locations of denser great white populations to tourism companies, allowing for a more efficient tourism sector. Lastly, a well-implemented monitoring system can facilitate introduction and reintroduction efforts for conservationists, by being able to non invasively monitor population health and size.
Featured image by: Hermanus Backpackers