Scientists finally know the clever tricks orcas use to hunt whale sharks

For the first time, scientists have captured video evidence of orcas collectively hunting whale sharks, the largest fish species on Earth. This graphic footage proves that whale sharks are an integral part of some orcas’ diets and solves the mystery of how they are able to kill the giant fish.

On May 26, shark ecologist Kathryn Ayres was leading tourists on a marine safari near La Paz, Mexico, when she saw a pod of orcas circling. “I knew a poor animal was being tortured,” Ayres said. “They like to play with their food.”

Along with photographer Kelsey Williamson, Ayres jumped into the water with her camera just in time to document five orcas taking down a young, 16-foot-long whale shark. Your video released today in Frontiers in Marine Science shows behavior in unprecedented detail.

To date, there has only been one other scientific report documenting orcas eating a whale shark, filmed by sport fishermen further south in Mexico, but it did not detail the full predation sequence. In addition to Ayres’ footage from this spring, the new research includes photos and videos of three other orcas that hunted these giant fish in the Gulf of California, Mexico. The first event in 2018 was caught on camera by a group of tourists who went snorkeling with sea lions on a rocky island north of La Paz. (They remained in their boat when the attack began.) The second and third events were also captured by tourists in 2021 and 2023.

With all these powerful photos and videos, scientists can now fully describe how the orcas kill the huge prey.

How orcas band together to hunt a whale shark

First, the orcas repeatedly ram a slow-swimming whale shark to stun it. When the fish loses its balance, the orcas work together to turn it upside down to expose its unprotected belly. “You could hear the crunch of the final blow,” recalls Ayres, which incapacitated the shark. The orcas then bite off the whale shark’s pelvic fins, causing it to bleed to death. They then eat the fish’s organs, including its huge fatty liver. It’s cruel and effective. Even birds took advantage of the feast and dived down for pieces of meat. “It was raining whale sharks,” says Ayres.

A male orca named Moctezuma, first spotted in 1992, took part in three of the four recorded robberies. This male orca may be the son of one of the pod’s matriarchs and may have learned his shark-eating techniques from her. He is often joined by four or five female or juvenile whales, which in one documented case launched an attack without him.

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This pod of orcas – called the Moctezuma pod – appears to have specialized in hunting cartilaginous fish. They also hunt stingrays, pygmy devil rays and bull sharks off the coast of southern Baja. (Moctezuma is named after the famous Aztec emperor. The females in the pod were also given Aztec names such as Quetzali, Niich or Waay, which means “witch” in Majan because their dorsal fin is shaped like a witch’s hat.)

The taste of this pod may be unique to whale sharks. “I have never heard of whale sharks being attacked by orcas anywhere else in the world,” said Simon Pierce, a whale shark conservation specialist who was not involved in the study and executive director of the Marine Megafauna Foundation. “But I can’t imagine that a whale shark has much of a chance if a group of killer whales attack it.”

Whale sharks fight back

The Gulf of California is known as a hotspot for whale sharks, particularly juveniles, which gather to feed in La Paz Bay every fall through spring. These younger sharks “may be naive to this type of predator,” Pierce says, which could be why orcas are targeting them. All four documented attacks occurred in April or May, when whale sharks left the protection of the bay to migrate south.