Additional video and reporting of orca predation on great white sharks in South Africa. I'm particularly struck once again by the massive size difference between the two species, particularly juvenile great white sharks compared to adult orcas.
www.smithsonianmag.com/smart-news/video-footage-captures-orcas-killing-great-white-sharks-180980911/
Video Footage Captures Orcas Killing Great White Sharks
The predation could explain why the sharks have been locally declining in recent years
For several years, scientists have suspected that orcas have been killing and eating parts of great white sharks off the coast of South Africa. Now, they have the video evidence to prove it.
Drone and helicopter footage captured in May shows orcas, also called killer whales, attacking and killing at least two great whites off Mossel Bay in South Africa’s Western Cape province, writes the Washington Post’s Rachel Pannett.
A video clip of the predation was released in the summer, but scientists shared more extensive footage with a new paper published last week in the journal Ecology, according to a press release.
“It’s probably one of the most beautiful pieces of natural history ever filmed,” Alison Towner, a great white shark biologist at the Marine Dynamics Academy in South Africa and the lead author of the paper, said to the Daily Beast’s Kevin Fallon in July.
Killer “whales,” which are actually dolphins, are apex predators, and their diet includes fish, squid, seals, sea birds and whales larger than themselves, according to the Natural History Museum in London. They are the only known predators of great white sharks.
Since 2017, eight attacked great whites have washed up on the shores of South Africa, according to Gizmodo’s Isaac Schultz. The sharks were missing hearts and livers—evidence that they had been killed by orcas. The number of great whites in the water off South Africa’s coast has also been declining in recent years, possibly due to orca predation, per the Post.
But scientists had never observed this behavior in detail—until now. The drone footage shows a group of five whales pursuing sharks for more than an hour, according to the Agence France-Presse (AFP). In one clip, two orcas swim near a shark while a third comes at it from below and pushes it toward the surface. Then, one of the other orcas bites the cornered prey, creating a pool of blood. The researchers hypothesize that three other sharks may have also been killed, according to the release.
The study didn’t try to answer why the orcas are targeting great whites, but Towner told Gizmodo in June that it could be “for their lipid-rich, nutrient-dense liver.” Great white shark livers could make up one third of the animal’s body weight, she tells the publication.
Videos and photos from the helicopter pilot appear to show an orca eating a piece of floating shark liver, writes the Post. That particular orca is believed to be an individual named Starboard—a suspected shark-killer. This was the only orca of the five thought to have previously attacked great whites, suggesting to the researchers that the others are learning the practice from Starboard, per the AFP. (Another orca not captured on video, named Port, is also suspected to be killing great whites.)
After watching the footage, scientists now believe the sharks try to evade capture by employing a technique also used by seals and sea turtles: circling the orcas and staying in their sight, writes the Post. But that technique likely proved ineffective, since orcas hunt in groups. Following the attacks, great white sharks fled the area—only one was spotted there within the next 45 days, per the AFP.
“Killer whales are highly intelligent and social animals,” Simon Elwen, a co-author of the study and a marine mammal specialist at Stellenbosch University in South Africa, said in the release. “Their group hunting methods make them incredibly effective predators.”
