What kills great white sharks?

Video Footage Captures Orcas Killing Great White Sharks

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.”

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2 killer whales slaughter 17 sharks in 1 day

Port and Starboard are the names of two infamous killer whales (orcas) that swim off the coast of South Africa. Their names come from their rare collapsed dorsal fins: Port’s bends to the left and Starboard’s bends to the right. The pair went on a killing spree last week, attacking and killing at least 17 broadnose sevengill sharks in a single day (February 24, 2023). The whales ate only the sharks’ livers and left their bodies to wash up on the beach.

This pair of male killer whales gained notoriety in 2015, when scuba divers found several broadnose sevengill sharks dead. Eventually, researchers fingered killer whales Port and Starboard in the deaths. Then, in 2017 and 2019, great white sharks were washing up on the coast with just their livers eaten out of their bodies. By 2020, the formerly hundreds of great white sharks in South Africa’s False Bay had nearly all moved out of the area. But, as proved last week at Pearly Beach, two hours east of False Bay, Port and Starboard are still at it.

Alison Kock, a marine biologist in Cape Town, South Africa, shared the news on Twitter.

At least 17 sevengill #sharks have been killed by infamous #killerwhale pair Port & Starboard this week in South Africa. Only the livers were eaten with the leftover carcasses washing ashore [1/3] ? @MarineDynamics Christine Wessels pic.twitter.com/PQVk1KI9mF

— Dr. Alison Kock (@UrbanEdgeSharks) February 24, 2023

Why eat just their livers?

Time and again, the washed-up carcasses of the sharks shows that the killer whales are just targeting the sharks’ livers. The killer whales are biting the sharks between their pectoral fins, yanking out the livers and leaving behind the other organs. The killer whales must have learned at some point where to find this tasty meal and remembered it, because they leave behind no bite marks on other parts of the sharks’ bodies.

But why the liver? Livers in sharks are large: They account for up to a third of a shark’s body weight. And, they’re rich in fat, packed with nutrients the whales need.

Video of killer whales hunting sharks

Last October, Kock was part of a team that published the first evidence of orcas killing great white sharks. In the peer-reviewed paper in the journal Ecology, lead author Alison Towner and the team shared images from drone footage that captured the killer whales hunting and eating the livers out of great white sharks. Christiaan Stopforth took the video, which you can watch part of here:

Killer whales are not a threat to humans

Despite the gruesome feeding frenzy off the coast of South Africa, killer whales pose no threat to humans. According to LiveScience, there is no record of a killer whale in the wild ever killing a human. A killer whale’s diet normally consists of seals, squid, fish and so forth. Humans are not on the list, although now it appears that sharks are.

On the other hand, four humans have died at the hands of killer whales in captivity. Three of those deaths were all due to the same killer whale, Tilikum, or Tilly. Tilly spent most of his life at Sea World in Orlando, Florida. The acclaimed documentary Blackfish chronicles the story of Tilly and the three tragic deaths.

Their floppy fins

Why are Port and Starboard’s dorsal fins floppy instead of upright? Simon Elwen at Sea Search answered that question for Shark Spotters at their Facebook page:

Male orcas are renowned for having extremely large, upright dorsal fins … Dorsal fins that are bent over or collapsed are relatively common in orcas that are in captivity, but only seen rarely in wild killer whales. In captivity, it is thought that the dorsal fins may bend over because the orcas are always swimming at the water’s surface, with the fin often sticking out of the water into the air … The fins are made from cartilage and are very heavy due to their size, and so without the support of water they are more likely to bend over.

In the wild, bent dorsal fins are most commonly associated with injury, such as an entanglement. However, although rare, there does appear to be some natural occurrence of bent dorsals among wild populations … One theory is that it could be diet related. And especially in shark-eating orcas such as Port & Starboard, it could be that they are not consuming enough calcium or other essential minerals for strong dorsal growth. Pollutants could be another possible cause, especially as shark-eating orcas are consuming prey that are at the top of the food chain and so … have higher levels of pollutants than lower order prey.

These two killer whales, anyway, are certainly living up to their name.

Bottom line: The killer whales Port and Starboard killed 17 broadnose sevengill sharks in one day off the coast of South Africa, dining on their livers and then letting the bodies wash ashore.