Orca have hunted and killed great white sharks. One of the first reported cases off the coast of California in 1997. And again in 2017 off South Africa, five dead white sharks washed ashore. Experts want to know whether it will happen again, and if so where? “Orca Vs Great White” is a 2021 documentary movie explores the related stories in New Zealand.
@ Orca Vs Great White Shark | Watch on National Geographic.
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Two apex predators dominate the ocean, the great white shark - a lone hunter and the orca, known as the killer whale. Both sit atop the oceanic food chain so when orca begin to hunt great white sharks in South Africa, it's big news.
The news is shocking. Scientists conducted an investigation. Of all the evidence collected, it was the bite marks on the shark bodies that revealed the killers. The teeth marks belonged to orca.
Why New Zealand is selected as the location for Orca Vs Great White relations?
Shark scientists wondered why orca would hunt dangerous prey like a white shark. With attacks happening in oceans around the world, experts are looking for similarities and patterns, and what the effect would be on the marine ecosystem, particularly in New Zealand.
When the orca started to kill the great white sharks in South Africa, the rest of the sharks actually disappeared and haven't come back for years. So South Africa is not an ideal location for further scientific research of their behaviors.
If that happened in New Zealand, not only would we lose this population of great whites that we've learned so much about but it would also be disastrous for this ecosystem to lose an apex predator like that.
There are several theories about exactly why the sharks vanished. But the coincidence of the orca attacks and the disappearance of the sharks is hard to ignore. And there's a lot at stake, including the health of the marine ecosystem.
New Zealand has a local orca population of between 150 and 200. While the white shark aggregation here is one of the largest in the world, estimated to be over 5,000. If the orca begin to go after white sharks here, they have plenty to choose from.
Orca could be hunting great white sharks already. But no white sharks have washed up on New Zealand beaches.
So the researchers are searching for other signs of orca predation. Any strange behavior, wounds from an encounter, anything that points to orca hunting white sharks.
Local great whites are in New Zealand waters from December to June, when many will leave on their annual 2,000 mile migration, to the coast of Australia, and the Tropical Pacific.
Local orca, on the other hand, remain in New Zealand waters all year round, roaming the coastline in search of prey, there are an estimated population of 200 or so orca living in New Zealand's waters.
Orca and white sharks are the top two ocean predators. Yet they're fundamentally different.
Speices: Orca are air-breathing mammals. White sharks are water-breathing fish.
Hunting habits: Orcas live in pods of up to 40, made up of individual family units that remain together for life and hunt cooperatively. Some new research suggests white sharks may occasionally hunt in groups. But they tend to hunt alone.
Size: The largest great white ever recorded measured over 20 feet and weighed 5,000 pounds. Small for an orca. Killer whales can grow to 30 feet or more. And weigh as much as 20,000 pounds.
But as different as they are, orca and great whites are both sophisticated, tough, and hungry predators.
Why orca hunt great white sharks?
In the above-mentioned serial killing in South Africa, the killer whales had taken only the shark livers and left the rest of the bodies untouched. This was the first recorded case of orcas killing white sharks in South Africa.
To hunt, mate, and migrate thousands of miles, it takes lots of energy for orca. Liver is pure fuel. So when they hunt, they're filling the tank.
New Zealand orca feed on the 25 species of rays and skates that swim in local waters. The preference for rays is unique to orca in New Zealand.
But recently local orca have acquired a taste for shark liver, from a smaller cousin of the great white, the sevengill. And evidence suggests South African orca started on sevengill sharks and graduated to great whites.
New Zealand orca are hunting sevengill sharks, just like the South African orca.
Sevengill sharks grow to nine feet long and 200 pounds. A much larger meal for an orca than a small ray. But the sevengill shark is no easy prey.
Scientists here got footage of the orca with the sevengills where they've ripped the pectoral fin, right under the pectoral girdle there. The way the orca hunt the sevengills is pretty impressive. First of all they'll come in and they'll karate chop the shark, so they'll just come and lift their tail up and whack them on the back. Then they grab the sharks by the pectoral fin and rip them open and pull the livers out.
A concentration of sevengill sharks lives up along the western coast of New Zealand. Sevengills may be prey for orca, but these sharks are no pushovers. Lower sevengill numbers could mean a few things are going on including predation by larger predators, like orcas.
But, filling up on rays and skates can be hard work and burn a lot of precious energy, and ray hunts don't always go smoothly. Rays often flee to shallower water, making it dangerous for the orca. There is the risk of a fatal stranding as the tide goes out. And the ray may still escape.
After a lot of work and coordinated effort among several orca, they catch the ray but it's a tiny payoff for all that effort.
And compared with white sharks, rays are just a snack for orca.
One 700-pound great white shark liver could be equivalent to nearly 175 ray livers. And it's a lot more work to hunt multiple rays. While it is more dangerous to hunt a single great white, it might be worth the risk.
A great white liver can grow to 25% of the shark's total weight. If a 12-foot great white weighs 1,000 pounds, it may have a liver weighing 250 pounds. A big pay-off for the orca.
If the rays were removed from the food web here in New Zealand, chances are the orca would shift their food preferences. And they could start targeting great white sharks in earnest. So far the supply of rays and skates has been ample. A shark of big size would be a feast for a whole family, not just one orca.
But after the orca killed five great whites in South Africa, all the other white sharks disappeared. In New Zealand, all of these sharks are still here and hunting.
It seems that sharks are not scared of orca enough to flee away. Researchers conduct some orca sounds tests to see the reactions and behaviors of sharks. You can explore more in the video.
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