Orcas May Be The Culprits Behind Disappearance Of South Africa's Great White Sharks

What has been causing South Africa's great white sharks to suddenly disappear? Experts believe that a pair of orcas might have something to do with it.

Great white sharks are iconic in South Africa's waters and there has been recent concerns over the steep decline in the sightings of these predators. Since 2015, sightings of great white sharks at False Bay and Gansbaai have been dropping.

The disappearance of these great whites could be due to several factors, including overfishing, illegal shark hunting, pollution, and the depletion of prey. However, their disappearance also happened to coincide with the arrival of two orcas in False Bay in 2015.

Orcas, also known as killer whales, have been known to hunt sharks, and this particular pair reportedly preyed on several seven-gill sharks in 2015, resulting in the species' disappearance from a large area. In 2017, the pair also was suspected to have attacked at least five great white sharks, a report from a government-appointed team noted. The number may have been higher, because sharks carcasses don't always wash ashore.

Considering this, the team suggested that killer whales could have killed great white sharks, or simply caused the sharks to flee.

"Therefore, the increased presence of these shark specialist killer whales may explain why white sharks have remained absent in False Bay and Gansbaai, but present in Mossel Bay, Plettenberg Bay and Algoa Bay," the team wrote in the report.

The orcas were only observed in Plettenberg Bay once and in Algoa Bay twice, the team explained. They have not been observed in Mossel Bay. On the other hand, the orca pair has been observed a total of 41 times in False Bay and Gansbaai, both of which are areas that great white sharks have fled and stayed away from for a prolonged period of time.

Still, the team recommended further investigation on the possible "conclusive" reasons for the great white sharks' disappearance. This includes studying the ecosystem, the sharks' diet, and the orcas' movement and diet.

The sharks' disappearance has already caused changes in the ecosystem, the report said, with their absence in some areas prompting the appearance of other shark species. What's more, it has also hurt tourism in the area.

In the past, many people could easily observe the sharks, whether from boats or inside diving cages.

"This has had a devastating impact on the shark diving industry and caused immense disappointment to the hundreds of tourists who visit our shores to see this great predator," Minister Barbara Creecy said Tuesday during the Expert Panel Review of South Africa's National Plan of Action for the Conservation and Management of Sharks.