2024-03-02 07:55:00
An image of a killer whale hunting a great white shark alone off the coast of South Africa in June last year/Christiaan Stopforth/Drone Fanatics SA
2024.03.02 Sat posted at 16:55 JST
(CNN) A pair of orcas work together to end a great white shark. Scenes like this have been unfolding along South Africa’s coast since at least 2017. Killer whales only take the nutrient-rich liver from sharks and throw away the rest.
Scientists have long tried to understand how killer whales hunt. Sharks have disappeared from parts of the coast around Cape Town, chased by killer whales.
Last year, scientists watched from aboard a boat as a male orca known as Starboard killed a young 2.5-metre great white shark in less than two minutes. “While we are in awe of these predators, our concerns for the balance of coastal marine ecosystems are deepening,” Primo Miccarelli, a marine biologist at the Shark Research Center at the University of Siena, said in a statement. “I’m doing it,” he said.
It is not unprecedented for killer whales, which are highly intelligent and social, to hunt large animals alone. However, until now, no known cases involving great white sharks, one of the world’s largest predators, have been confirmed. The researchers reported this in the daily journal Marine Science.
Starboard’s hunting method differs from what has been widely observed in the past, where multiple killer whales work together to surround and attack prey. According to research, attacks on great white sharks have previously been observed to involve two to six sharks and take up to two hours to kill.
Alison Towner, a researcher at South African Rhodes University and lead author of the new study, points out that solitary hunting provides groundbreaking insight into killer whales’ feeding behavior. He suggested that the presence of killer whales that hunt sharks might be linked to broader ecosystem dynamics.
Dead great white shark washed up on shore near Hartenbosch, South Africa
The incident detailed in the paper occurred on June 18 last year, 800 meters off the coast of Seal Island, near Mossel Bay, regarding 400 kilometers east of Cape Town. At the time, researchers and tourists were on two ships observing the killer whales.
Within an hour of arriving, a shark surfaced. People saw Starboard capture the shark’s left pectoral fin. Starboard rammed the shark several times, eventually pulling out its internal organs. The paper records that it took less than two minutes.
A photo of Starboard was later taken from one of the vessels with “a pink liver covered in blood in his mouth”. Starboard’s male companion, Port, was also seen regarding 100 meters away, but he was not involved in the hunt.
The two killer whales are well-known to the study’s authors, and are believed to be swimming along the coastline of eastern South Africa, all the way to Namibia. They are believed to have started targeting great white sharks in 2015, but Towner said it wasn’t until 2022 that multiple orcas were actually photographed hunting them from the air.
The paper suggests that one orca may have been able to kill the great white shark because it was young and relatively small. The maximum length of an adult great white shark is 6.5 meters. It weighs up to 2.5 tons.
The speed of the attack appears to reflect Starboard’s skill and efficiency as a predator. The paper suggests that such factors may be a response to the stress of spending time hunting. The coastline near where they hunt is also an area where many people live.
Dr Simon Oelwen, a researcher at South Africa’s Stellenbosch University and founder of the marine research institute Sea Search, said killer whales can quickly learn new hunting techniques on their own or from other individuals. I explained that I might do it. He said observing and understanding the behavior of killer whales in South Africa would play an important role in deepening knowledge of the animals.
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