Killer whales have been caught on camera hunting and eating great white sharks for the first time, in an hour-long feeding frenzy.
The extraordinary scenes were shot by both helicopter and drone pilots off the coast of South Africa, providing the first direct evidence of killer whales preying on sharks.
They reveal that the killer whales attacked at least four sharks in about an hour, and that this unusual predatory behavior may have spread within the species.
While a short drone video of the attack was released in June, a paper analyzing the clip plus all the footage taken from the helicopter has been released this month.
Researchers from the Marine Dynamics Academy studied the videos and analyzed drone and cage diving boat survey data before and after these predation events.
Lead author and PhD student Alison Towner said: ‘This behavior has never been seen in detail before – and certainly never from the air.’
Only two killer whales in South Africa have previously been associated with white shark hunting, but it has never actually been seen ‘in action’ before these clips. One of these killer whales, known locally as ‘starboard’, is seen in the new footage eating what is believed to be a large piece of shark liver at the surface of the sea
WHY DO ORCAS HUNT GREAT WHITE SHARKS?
Orcas are the only natural predator of the Great White.
Scientists have found evidence that they tear the sharks open and eat their fatty liver.
Scientists speculate that this behavior may be behind the disappearance of great whites from the waters of False Bay, off the coast of Cape Town.
Great Whites frequented the area between the months of June to October each year as part of their annual winter hunting season.
They were attracted to the region by the presence of the so-called seal island, a rock that is home to a huge seal colony.
However, they themselves have fallen to begging killer whales – and are on the retreat.
Killer whales have previously been filmed preying on other large marine species such as blue whales, tiger sharks and sevengill sharks.
A paper, published today in Ecologypresents the first footage of five killer whales stalking, capturing and incapacitating a group of great white sharks.
They can be seen ripping open the torsos of their prey to gain access to their nutrient-rich livers and hearts.
Only two killer whales in South Africa have previously been associated with hunting Great Whites, but this has never actually been seen ‘in action’ before these clips.
One of these killer whales, known locally as ‘Starboard’, is seen in the new footage eating what is believed to be a large piece of shark liver at the surface of the sea.
David Hurwitz, a boat-based whale watching operator from Simon’s Town Boat Company, said: ‘I first saw Starboard in 2015 when he and his crony ‘Port’ were linked to the killing of seven gill sharks in False Bay.
‘We saw them kill a bronze whaler [copper shark] in 2019 – but this new sighting is really something else.’
However, the researchers believe that the involvement of four new whales, one of which bit a shark in the area of the liver, suggests that the behavior may be spreading.
While only one predation incident was observed, the researchers believe that three other sharks may have also been killed during the attack.
A paper, published today in Ecology , presents the first footage of five killer whales stalking, capturing and incapacitating a group of great white sharks.: Pictured: Two killer whales, including the infamous ‘starboard’
Only a single great white shark was seen in the 45 days following the predations, confirming that the sharks escaped from the Mossel Bay region
WHALE VS GREAT WHITE SHARKS
Size: Over six tons
Length: Up to 30 feet
Habitat: All oceans
Life: Up to 90 years
Great white sharks
Size: 2.5 tons
Length: Up to 22 feet
Population: Fewer than 3,500
Habitat: All temperate coastal waters
Life: Up to 70 years
Predator: Orcas, people
For the study, the researchers analyzed the sharks’ attempts to evade capture by killer whales in the videos.
On two occasions, killer whales approached sharks closely and slowly, while instead of fleeing, the shark stayed close to the predator and kept it in view.
This is a common strategy used by seals and turtles used to escape sharks. But when killer whales hunt in groups, the researchers believe that it can be ineffective in this situation.
Co-author Dr. Simon Elwen, a research associate at Stellenbosch University, said: ‘Orcas are very intelligent and social animals. Their group hunting methods make them incredibly effective predators.’
In addition to looking at the events in the footage, the researchers analyzed drone and cage diving boat survey data before and after these predation events.
Great white sharks had been seen on every survey day for weeks before the attack, and several sharks were also seen on the day of it.
However, only a single white shark was seen in the 45 days following the predations, confirming that the sharks fled the Mossel Bay region.
Dr. Alison Kock, South African National Parks’ shark expert, said: “We first observed the flight response of seven gill and great white sharks to the presence of port and starboard killer whales in False Bay in 2015 and 2017.
‘The sharks ultimately abandoned previously key habitats, which has had significant knock-on effects for both the ecosystem and shark-related tourism.’
At least seven great white shark carcasses have washed ashore in False Bay, South Africa, since 2017, with teeth indicating they were rescued by killer whales. Great Whites that encounter killer whales will immediately leave their usual hunting grounds for up to a year
Previous studies have documented how new behaviors spread among killer whales over time through cultural transmission.
The authors suggest that if more killer whales adopt the practice of hunting great white sharks, then the behavior will have a much wider impact on shark populations.
It is hoped that their findings will lead to the development of better conservation strategies for white sharks.
The number of sharks in the open ocean has fallen by more than 70 percent in just 50 years.
Three quarters of species are threatened with extinction – including the Great White – with factors including climate change and overfishing.
A pair of killer whales have killed at least eight great white sharks off the coast of South Africa since 2017
Two killer whales are believed to have killed at least eight great white sharks off the coast of South Africa since 2017, and managed to scare away many more.
Scientists found that great whites have avoided certain areas of the Gansbaai coast for fear of being hunted by killer whales.
Many of the shark carcasses washed up without their livers and hearts or with other injuries characteristic of the orca pair.
The study used long-term observations and tag data. Over the course of five and a half years, 14 sharks were tracked fleeing the areas when the whales are present.
Shark experts at the Dyer Island Conservation Trust claim this suggests marine predators trigger the ‘flight’ fear response in sharks when they are nearby.
This in turn results in their rapid, long-term exodus from the area, creating an opportunity for an influx of new predators to deplete other species.
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