‘Awe-inspiring and harrowing’: how two orcas with a taste for liver decimated the great white shark capital of the world | Sharks

RIt was first washed up in a great white carcass, a young female, in South Africa on February 9, 2017. The 2.6-metre-long body has no hook or net, ruling out human involvement. Everything that killed her was gone. And so it was All other great white sharks At Gansbaai on the Western Cape, observed Dr Alison Towner.

“We had several acoustically tagged sharks, and they later realized that three had moved further out of Plettenberg Bay and Alga Bay, more than 500 kilometers away.” [300 miles] says the Rhodes University marine biologist.

It wasn’t until May that shark sightings returned to their peak. then Three more bodies were found Over a period of five days, followed by the fifth in June. For eight odd weeks, not a single great white shark was seen.

It was Gansbay It had a population of 800-1000 great white sharks in 2010However, with all the sharks killed in the Gulf, they fled longer and returned in smaller numbers. When a sixth sacrifice appeared In June 2021, they did not return for another year.

At the time of the first deaths, Towner had only recently begun a PhD on the movement of white sharks, which has now been curtailed. “Watching the predators I had dedicated my life to studying washing up dead on the beaches was surreal, and something I will never forget,” she says.

Determined to solve the mystery, Towner and her colleagues led the names of the four deadliest sharks. It soon became clear that their deaths were connected. They were all torn in the pectoral girdle, just behind the nostrils, with surgical precision. Two bodies showed distinct rake marks. Most strikingly, all four were missing their livers.

All signs point to the same culprits: orcas.

Two male orcas that have frequented Gansbaai since 2015 are Towner’s immediate suspects. The names given by local zoologists were port and nabo, named for their distinctive dorsal fins, to the left and right respectively.

The pair were spotted off the coast of Gansbaai within hours of each dead shark being discovered. They were also seen killing seven sharks ((Notorynchus cepedianus) in the nearby lying bay and wandering on their livers.

Towner was certain that Port Winborough was responsible. “The only missing element is direct observation of an attack,” she says.

On May 16, 2022, Christian Stuptworth was flying a drone over Mossel Bay, about 190 miles east off Gansbaai, when he recorded something unusual: five Orcas attack a three-meter white sharkbiting between its pectoral fins and cutting off the liver. It was one of the starboard orcas.

“To see one of the ocean’s top predators defeated so easily,” says Esther Jacobs, founder of the Marine Conservation Foundation, who keeps Finn alive and is among the first to see Stopforth’s footage.

A helicopter crew witnessed three more killings that day. As in Gansbaai, the remaining white sharks in Mossel Bay have left the area. None returned for 45 days.

Finally, the following June, Port and others also returned To Mossel Bay. Jacobs was among those who jumped into a boat to observe them. When they reached the pair, there was a distinct pungent smell of shark liver in the air, indicating a recent kill.

Suddenly, a juvenile white shark appeared and charged to starboard.

“It was both awe-inspiring and horrific. Starlow’s immense strength was on full display as he held the shark firmly, even while being crushed,” Jacobs recalls. “We watched in stunned silence as he eventually screwed up the shark.”

It was the shark Dead in just two minutes, his liver devoured. Another carcass washed ashore the next morning, giving rise to at least a number of white sharks.

ROday, great white sharks have disappeared in Mossel Bay. “Since the 2023 incident, they haven’t come back in any meaningful way,” Jacobs says. “To my knowledge, there have been fewer than 10 confirmed observations in 2024.”

The disappearance of great whites from the region was a microcosm of what happens when sharks disappear from food chains. Great white sharks are often considered “Ocean DoctorsThis is glaringly evident with their absence in southern Africa as a population of their preferred prey, Head fur sealand Bronze whale shark Rose in Gansbaai.

This explosion of prey species could represent what ecologists call a trophic cascade, where the loss of a predator reverberates up the food chain, throwing the ecosystem out of balance.

Towner notes that the seals, no longer under threat, “have become bolder, some even outpacing the endangered African penguins.” The absence of sharks can also lead to illness: since June 2024, Seals in the Western Cape infected with rabies treatsThe epidemic of that She arrived in Mossel Bay in July.

“In my opinion, if the white shark population had been at its previous peak, they may have helped mitigate the rabies situation, because rabid seals would likely be easier targets,” Jacobs says.

These damaged ecosystems could be a grim reflection of the future of our oceans; Something beyond two orcas. While Port and Starboard provide an exciting glimpse into how the ecosystem is rapidly changing, the greatest extinction threat facing all sharks is humans.

Recent studies conducted by Professor Nicholas Dolphy, at Simon Fraser University in Canada, have concluded that human activities, especially poaching, are driving… Global extinction of sharks and rays.

“After more than a decade of work, we now know that global abundance has been cut in half since 1970,” Dolphy says. Overfishing kills more than 100 million sharks a year and More than a third An endangered shark species.

Without effective fishing regulations, environmental damage in South Africa It could happen on a much larger scale. “The future for sharks looks bleak if overfishing continues,” Jacobs says.

Towner agrees with the shark conservation recommendations in Dulvy Reports: “Strengthening international policies to combat poaching, expanding marine protected areas and promoting sustainable fishing practices are key actions.

“That is, of course, if the science is listened to,” she adds.