Marine biologists say they have observed the first evidence of orca whales hunting great white sharks off the South African coast.
Great white sharks have been washing up on the beaches of Gansbaai (two hours east of Cape Town) with vital organs missing, including their livers and hearts.
The sharks had bite wounds consistent with what the marine biologists call “orca predation,” otherwise known as being hunted by killer whales.
Alison Towner, a marine biologist with the Dyer Island Conservation Trust, described the wounds as being made with nearly “surgical precision.”
“These observations are unprecedented,” she said in a blog posted by Marine Dynamics, a shark cage diving company associated with the Dyer Island Conservation Trust.
“We have identified and matched each of the three dead white sharks in our database, but the fact is from now on, this is a gray area and we don’t really know how long the sharks will stay away from the area as a result of predation pressure.”
Towner told The Australian that the behaviour is quite rare.
“The observation of orca killing a great white shark has only been seen twice in different locations in the world before, and in both cases it was an offshore event seen from a boat,” she said. “In South Africa we’ve never seen this before. It’s unique.”
As apex predators, orcas are known to eat everything from sharks to seals to even moose, according to LiveScience. They are also the only known predators of great white sharks, besides humans.
Scientists believe the orcas in the area are targeting the sharks’ livers, which are rich in squalene, a chemical compound found in fish oil or shark liver oil.
“They work together and are very co-ordinated. Two orcas will take a pectoral fin in their mouth and pull open a shark together to extract the liver,” said Towner.
The impact of these predatory actions on the great white shark population, said Towner, is cause for concern. Great whites are already a vulnerable species and this could impact the local eco-tourism economy.
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