Killer whale pair kills 17 sharks a day

A pair of killer whales off the coast of South Africa kill sharks to remove their livers while leaving the other parts intact .

The carcass of a shark with its liver removed washed up on the beach. (Photo: Academy of Marine Dynamics)

Two killer whales, named Port and Starboard by marine conservationists, have disrupted the food chain in the waters off Cape Town and led to a decline in the great white shark population. Last week, researchers from the Academy of Marine Dynamics found a total of 17 shark carcasses in one day. They had been tracking Port and Starboard's hunting habits since they first appeared in the area in 2015. Each shark was mangled and missing its liver, a nutrient-rich organ that killer whales love.

The team of experts believes that Port and Starboard specialize in eating livers because they contain a compound called squalene, which plays an important role in hormone production. Killer whales can extract livers from sharks with great precision. Working together, the killer whales force the sharks to the surface, turning them upside down, before biting into their bellies to remove the livers. Except for the livers, the sharks' other internal organs remain intact.

Killer whales, the only predators of great white sharks , are highly intelligent and skilled hunters. In addition to sharks, they also eat seals, dolphins, turtles and squid. The bold hunting skills of Port and Starboard in South Africa allowed researchers to determine that the sharks had a flight response. A study published in October 2022 found that the sharks were afraid to return to their natural hunting habitat because they were threatened by the orca's predation.

'We first observed the flight response of white sharks to the presence of Port and Starboard killer whales in False Bay in 2015 and 2017. The sharks abandoned their previous habitat, causing major impacts on both the ecosystem and associated tourism ,' said Dr Alison Kock, shark expert at South African National Parks.

Previous studies have documented new behaviors spreading among killer whales over time through cultural transmission. The team hopes their findings could help develop better conservation measures for great white sharks, whose global population has declined by more than 70 percent in just 50 years.