Mysterious great white shark death off South Africa; were orcas involved?

A dead great white shark was discovered Thursday off Pearly Beach, South Africa, and there's speculation that orcas might have killed the shark.

The carcass of a juvenile female white shark was retrieved by members of the Dyer Island Conservation Trust. There were no signs of physical trauma, but there were peculiar markings on the shark.

"There will no doubt be speculation that Orcinus orca is responsible for this mortality as only yesterday we documented two male orca in the area," Dyer Island Conservation Trust stated on its Facebook page. "[But] the fact is we cannot confirm this, it could also just be a coincidence."

It's hoped than an autopsy will reveal the cause of death.

Orcas, or killer whales, rarely interact physically with great white sharks, but it's not unprecedented.

In 1997 off San Francisco, whale watchers witnessed an adult female orca killing a juvenile white shark. The orca was photographed with the shark in its mouth.

An orca carries a sevengill shark it had helped kill off California. Photo: Courtesy of Slater Moore/Monterey Bay Whale Watch

In 2015 off South Australia, a family group of orcas was involved in the killing of a white shark popular among cage divers.

In some areas, orcas commonly prey on other types of sharks.

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Last December off Monterey, Calif., a pod of offshore killer whales passed around a large sevengill shark that it had killed. That was captured via drone-cam.

In New Zealand, orcas commonly prey on smaller sharks.

Ingrid Visser, who has studied killer whales for nearly 20 years, told the Telegraph that orcas use a specialized technique to stun their prey: “The orca will use its tail to drive the shark to the surface. They don't even touch it. Using an up-thrust of its tail it creates a vortex which pushes the shark up on the current they create with their movements.

"Once the shark is at the surface, the killer whale pivots and lifts its tail out of the water and comes down on top of it like a karate chop."