Two orcas have killed and chased great white sharks out of South African waters; here’s why

It was 2015. A strange phenomenon was beginning to occur in the seas around Cape Town, South Africa. Dead great white sharks began washing up on the beaches near the city. A particularly gruesome aspect of the carcasses was that the liver had been ripped out.

Over seven years later it is now known whose work it was. However, what is not known is why, according to experts in a recent webinar.

The shark killers were two male orcas, or killer whales, euphemistically named “port” and “starboard” because their dorsal fins rotate.

The environmental and economic damage they cause is still affecting communities along the coast of the Western Cape province of South Africa – in the area from False Bay in the west to Plettenberg Bay in the east.

The webinar Great White Sharks and Orca in Plettenberg Bay was organized by Leadership for Conservation in Africa, a South Africa-based non-profit conservation organization. The keynote speaker was Justin Blake, a shark scientist and entrepreneur.

Deadly duo

Port and starboard were first seen in Lüderitz, Namibia in 2009. Their range extends from Lüderitz to Port Elizabeth in South Africa and they have always been seen on the coast in shark hotspot areas. They have eaten smaller species of sharks.

“We don’t know if they were preying on larger shark species offshore,” said Dave Hurwitz, an expert on whale behavior in False Bay.

He added that he had always suspected the duo were part of a larger clan. “That makes it very interesting, but also very worrying for the future. Have port and starboard through cultural transmission taught other orcas how to hunt larger sharks, or have they always done so?” wondered Hurwitz.

According to Allison Towner, a senior white shark biologist, port and starboard arrived in South Africa as adults, with a specific strategy for hunting sharks that they obviously learned from somewhere.

But why great whites? South Africa isn’t the first place killer whales have eaten the iconic species of shark made famous by the 1975 Hollywood film Jaw based on the novel of the same name by Peter Benchley.

Great whites have been eaten by orcas in California and South Australia. “It’s been a long time since California was in the 1990s. The orcas ate the livers of the sharks, but no carcass washed ashore as it was far out to sea,” Towner said.

In 2019, a cage dive boat spotted great white sharks off the Neptune Islands in South Australia. A pod of orcas came and killed a shark within sight of the boat. In both cases, the Great Whites left the locations the following season.

“South Africa is not the first place this has happened, but it is the first place in the world where cadavers have been washed ashore and autopsied,” Towner said.

South Africa is also the first place in the world where drone footage has been taken of orcas chasing sharks as they try to avoid them, she added.

Blake said it’s common knowledge that animals can learn and remember. “These animals may come here because they may remember that there is easy prey. When the numbers have decreased, they move away according to natural cycles that we see across the planet,” he said.

shark cage industry

Great white sharks have largely abandoned areas such as False Bay (with Seal Island in the middle), the town of Gansbaai, Mossel Bay and Plettenberg Bay since port and starboard began hunting in 2015.

This has dealt a severe blow to the shark cage diving industry in the region, which provides livelihoods and sustains communities.

Great white sharks were the main attraction in the years leading up to 2015. Tourists and other visitors used to pay handsome sums to climb into steel cages and dive to see the sharks in their natural habitat.

Schools of orca visited the area prior to 2015. However, they have never been known to exclusively hunt sharks.

The two years of the COVID-19 pandemic – 2020 and 2021 – had made things even harder for shark cage diving operators.

“The port and starboard impact on the shark cage diving industry has been devastating. But in this world of increasing uncertainty, you have to be able to adapt,” Blake said.

Hurwitz sounded positive. “As the great whites left Seal Island, the sevengill and copper sharks began to invade. From a shark cage operator’s business perspective, it’s not the same.

“But they have other ways that they can show. People really enjoy seeing copper sharks and learning about other species. They also dive with blue sharks. Although the great whites are gone, there is still a lot of interest in the False Bay sharks and people are supporting the companies,” he said.

All eyes will now be on a new paper on killer whales in South African waters, due to be published soon, which will shed more light on the evolving relationship between orcas and great whites in the seas around South Africa.