TOn February 9, 2017, he washed up the first carcass of a great white, a small female, in South Africa. There were no signs of hooks or nets on the 2.6-meter-long body, ruling out human involvement. Whoever had killed him had disappeared. So it was All other great white sharks In Gansbaai on the Western Cape, Dr Alison Towner observed.
“We had a number of sharks acoustically tagged, and later realized that three had gone as far as Plettenberg Bay and Algoa Bay, more than 500km away. [300 miles] east,” says a marine biologist at Rhodes University.
It wasn’t until May that shark sightings returned to their peak. Then Three more bodies have been found. Over five days, followed by a fifth in June. For eight terrifying weeks, not a single great white shark was seen.
Gansbai had. A population of 800–1,000 great white sharks in the 2010sBut with each kill, the Gulf sharks continued to flee longer and returned in smaller numbers. When the sixth body appeared. In June 2021, he did not return for another year.
At the time of the first death, Towner had recently begun his doctorate on the movements of great white sharks, which had now been reduced. “Watching the predator I had devoted my life to wash up dead on the beaches was surreal, and something I will never forget,” she says.
Determined to solve the mystery, Towner and his colleagues exhumed the carcasses of four sharks that had recently died.. It quickly became clear that their deaths were connected. All were cut open at the breastbone, just behind the gills, with surgical precision. Two bodies had distinctive rack marks. Most amazingly, all four were missing their livers.
All signs point to the same culprits: orcas.
Two male orcas that had frequented Gansbaai since 2015 were Towner’s immediate suspects. The names given to them by local zoologists were port and starboard, labeled by their distinctive dorsal fins, collapsed on the left and right sides, respectively.
Within hours of each dead shark being discovered, the pair were spotted off the coast of Gansbaai. They were also seen killing seven-gill sharks. (Notorhynchus sapidensis) in nearby False Bay and staring at their livers.
Towner believed port and starboard were responsible. “The only element that was missing was direct observation of the attack,” she says.
On May 16, 2022, Christian Stopforth was flying his drone over Mossel Bay, about 190 miles east of Gansbaai, when he recorded something unusual: five orcas attacking a three-meter-long great white shark, on its breast. Biting between the wings and ripping out his liver. . One of the arcas was starboard.
Esther Jacobs, founder of marine conservation charity Keep Fun Alive, and one of the first to see Stopforth’s footage, said: “It was heartbreaking to witness one of the ocean’s biggest predators being defeated so easily. “
A helicopter crew witnessed three more casualties that day.. Just as in Gansbaai, Mossel Bay’s surviving white sharks left the area. No one came back for 45 days.
Finally, in the following June, Port and starboard also returned. to Mosel Bay. Jacobs was among those who boarded the boat to observe them. When they approached the pair, there was a distinct, pungent smell of shark liver in the air, indicating a recent kill.
Suddenly, a juvenile white shark appears and charges to starboard.
“It was amazing and unsettling. The sheer power of starboard was on full display as it held the shark tightly, even as it was thrashing around,” recalls Jacobs. . “We watched in stunned silence as he finally released the shark.”
The shark died in just two minutes, consuming its liver. Another carcass washed ashore the next morning, bringing the death toll to at least three white sharks.
TToday, Mossel Bay’s great white sharks have all but disappeared. “Since the 2023 event, they haven’t come back in any meaningful way,” says Jacobs. “As far as I know, there have been less than 10 confirmed observations in 2024.”
The disappearance of great whites from the area has also served as a microcosm of what happens when sharks disappear from food chains. Great white sharks are often considered “Doctors of the Sea” This is clearly evident from their absence as their preferred prey population in South Africa. Cape fur sealand Bronze Whaler Shark Gansbai has increased.
This explosion of predator species may represent what ecologists call a trophic cascade, where the loss of a predator moves down the food chain, unbalancing the ecosystem.
Towner noted that the seals, which are no longer endangered, “have become much bolder, some even predating the critically endangered African penguin”. The absence of sharks can also bring disease: Since June 2024, seals in the Western Cape have been infected with rabies, an epidemic. Arrived at Mosel Bay in July.
“In my opinion, if white shark populations were at their previous peak, they could help reduce the rabies situation, because the rabies cells would potentially be easier targets,” says Jacobs. .
These damaged ecosystems could be a dire reflection of the future of our oceans. Something that transcends two arcas. While Port and Starboard provide a dramatic glimpse of how an ecosystem can change rapidly, the greatest threat to extinction of all sharks is from humans.
Recent research by Professor Nicholas Dolvey of Simon Fraser University in Canada has concluded that human activities, particularly overfishing, Global Extinction of Sharks and Rays.
“After more than a decade of work, we now know that global abundance has halved since the 1970s,” says Dolvey. Overfishing kills more than 100 million sharks a year. And More than a third Shark species are in danger of extinction.
Without effective fisheries regulations, environmental damage in South Africa could be massive. “If overfishing continues, the future for sharks looks bleak,” Jacobs says.
Towner agrees with and echoes the recommendations for shark conservation in the Dulvy reports: “Strengthen international policies to combat overfishing, expand marine protected areas and promote sustainable fishing practices.” Giving is the key steps.
“It certainly is, if the science is to be heard,” she adds.
