Author: Emma Rigney
Though the great white is considered the top marine predator, orcas may actually rule the oceans, new observations suggest.
WHEN ALISA SCHULMAN-JANIGER heard great white shark carcasses had washed up on South African beaches without their livers a few years ago, she was shocked.
“I was thinking, Déjà vu, here we go again,” says the biologist, a research associate at the Natural History Museum of Los Angeles County.
In October 1997, tourists in a whale-watching boat off the Farallon Islands, near San Francisco, witnessed two killer whales attack a great white shark and consume its liver.
It was, at that time, the first documented sighting of killer whales eating white sharks. The incident sparked new lines of research, as well as some intriguing questions for Schulman-Janiger and many others: How could any ocean predator, even one called a killer whale, dominate the almighty great white?
“From that moment on, everything seemed to be different as far as perspective about orcas and white sharks,” Scot Anderson, a seasonal researcher for Monterey Bay Aquarium, says in the Whale That Ate Jaws: Eyewitness Report, which airs July 16 at 10 p.m. ET as part of National Geographic Channel’s SharkFest.
“It completely changed everybody's ideas.” (Read why great whites are still a mystery to us.)
As it turns out, it wasn’t a fluke. In 2017, five white sharks were found beached on South Africa’s Western Cape. Though no one saw the South African killer whales—also known as orcas—kill the sharks, the parallels to the other attacks made orcas the likely culprits.
Overall, the incidents show that interactions between these two predators can have major impacts on the food chain, says Anderson. For instance, his recent study shows that the presence of orcas scares sharks away from elephant seal colonies in the Farallon Islands, which in turn benefits seals, the great white’s main prey.
Following the 1997 attack, the entire great white population—about a hundred animals—left the islands prematurely and skipped their annual seal smorgasbord, Anderson says.
Between 2006 and 2013, the team tagged 165 white sharks with acoustic tags, and confirmed their hypothesis: The years that great whites crossed paths with orcas, they ate fewer seals.
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