Two killer whales have killed and driven great white sharks from South African waters; here’s why

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

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

The shark killers were two male killer whales or killer whales euphemistically named ‘Port’ and ‘Starboard’ for the directions in which their dorsal fins rotate.

The ecological and economic damage they have caused continues to affect communities along the coast of South Africa’s Western Cape province, in the area from False Bay in the west to Plettenberg Bay in the east.

the webinar White sharks and killer whales in Plettenberg Bay It was organized by Leadership for Conservation in Africa, a non-profit conservation organization based in South Africa. The keynote speaker was Justin Blake, a shark scientist and entrepreneur.

deadly duo

Port and Starboard first saw each other in 2009 in Luderitz, Namibia. Their area of ​​distribution extends from Luderitz to Port Elizabeth in South Africa and they have always been seen on the coast, within the areas of greatest danger for sharks. They have been preying on smaller shark species.

“We don’t know if they’ve been hunting larger shark species on the high seas,” said Dave Hurwitz, an expert on cetacean 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 going forward. Have both starboard and board, through cultural transmission, taught other orcas to hunt larger sharks or have they always been doing this? Hurwitz wondered.

According to Allison Towner, a senior great white shark biologist, Port and Starboard came to South Africa as adults, with a specialized shark-hunting strategy, which they obviously learned from somewhere.

But why great whites? South Africa is not the first place where killer whales have preyed on the iconic shark species, made famous by the 1975 Hollywood movie. jaws based on Peter Benchley’s novel of the same name.

Great whites have been preyed on by killer whales in California and South Australia. “California was a long time ago in the 1990s. Killer whales ate the liver of the sharks, but no carcasses washed up on shore as it was so far out at sea,” Towner said.

In South Australia in 2019, a cage dive boat off the Neptune Islands was observing great white sharks. A pod of killer whales came and killed a shark within sight of the boat. In both cases, the white sharks left the sites the following season.

“South Africa is not the first place where it has happened, but it is the first place in the world where carcasses wash up on shore and undergo necropsies,” Towner said.

In addition, South Africa is the first place in the world where drone footage has been obtained of orcas chasing sharks, which in turn are trying to evade them, he added.

Blake said that it was well known that animals could learn and remember. “These animals may be coming here because they can remember that easy prey is available. When the numbers have decreased, they move away following the natural cycles that we see all over the planet,” he said.

Shark cage industry

Great white sharks have largely left areas like False Bay (with Seal Island in the middle), the town of Gansbaai, Mossel Bay, and Plettenberg Bay since Port and Starboard began their hunting spree in 2015.

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

Great white sharks were the main attraction in the years prior to 2015. Tourists and other visitors used to pay large sums of money to enter steel cages and dive to see sharks in their natural domain.

Groups of killer whales visited the area before 2015. But they were never known to exclusively hunt sharks.

The two years of the COVID-19 pandemic, 2020 and 2021, made things even more difficult for shark cage diving operators.

“The port and starboard effect 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 struck a positive note. “When the white sharks left Seal Island, the sevengill and copper sharks began to move. It’s not the same from the business perspective of shark cage operators.

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

Now all eyes will be on a new article on killer whales in South African waters which will be published soon and will shed more light on the evolving relationship between killer whales and great whites in South African seas.