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South Africa’s Great White Sharks Could Be In Danger Of Extinction, Study Reveals

By Dustin Wicksell
Published on: 03:27 PST, Jul 24, 2016

South Africa’s resident population of great white sharks has declined dramatically in recent years, leaving the species in danger of extinction in the region and potentially threatening to upset the delicate balance of the local ecosystem, a new study has concluded.

That dire prediction is the result of a six-year-long population analysis conducted by researchers at Stellenbosch University in South Africa, and published last month in Marine Ecology Progress Series. As Quartz notes, the study is considered the largest undertaking of its kind ever conducted in relation to South Africa’s white shark population, and was primarily carried out near Gansbaai. The researchers utilized genetic sampling techniques and analyzed unique and distinguishing markings on individual shark’s dorsal fins in order to identify them.

What they discovered was that the great white shark population in South Africa has declined to a point where it may be unsustainable. As CNN points out, there are believed to be only between 353 to 522 individual sharks left in the country’s waters, a number that is likely too small for a successful breeding population.

Lead researcher Sara Andreotti noted that previous research suggests a population of at least 500 animals is required to avoid inbreeding depression. Of the white sharks that were documented as a part of the study, only 333 are capable of contributing offspring to the next generation. The researchers also noted that South Africa’s white sharks exhibit unusually low genetic diversity when compared to members of their species from other parts of the world.

“The numbers in South Africa are extremely low. If the situation stays the same, South Africa’s great white sharks are heading for possible extinction.”

A number of factors are believed to have contributed to the white sharks’ population decline, though Andreotti specifically pointed to fishing, as well as the use of shark nets and baited hooks in the eastern parts of the country. In addition, poaching and habitat encroachment, as well as pollution and a decline in food sources have all posed significant challenges to the region’s great white sharks.

Though multiple factors are at work, the study also suggests that measures put in place to protect beachgoers from sharks, like nets and baited drumlines, are responsible for killing as many as 1,000 of South Africa’s great whites between 1978 and 2008. These tactics have proven to be controversial when employed in other parts of the world, particularly in Australia, which is also home to a significant population of great white sharks. In Western Australia, for example, government policy allows officials to specifically target and kill white sharks if they are thought to pose an imminent or serious threat to public safety, as the Inquisitr has previously noted.

The loss of the region’s great white sharks could potentially unleash dramatic and unexpected consequences, both ecological and economic. The study notes that the great white sharks are crucial participants in the marine ecosystem, and as apex predators their loss would set in motion “a cascade of detrimental effects on the ecological stability” of South Africa’s marine environment.

“The survival of South Africa’s white shark population and the ecological interactions of the coastline will be seriously compromised if urgent management measures to prevent the decline are not put in place.”

For example, the researchers predicted that a further decline in the shark population could increase the number of fish-eating seals (which the great whites currently keep in check), thereby directly impacting local fisheries. The sharks’ loss could also negatively impact the country’s tourism industry, as a number of cage diving companies operate along the coast in order to bring divers face-to-face with the great whites.

[Photo by Elias Levy via Flickr | Cropped and Resized | CC BY 2.0]

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