Scientists finally know the clever tricks orca use to hunt whale sharks
New, unprecedented images reveal how orca take down the largest species of fish on Earth.
For the first time, scientists have captured video evidence of orcas cooperatively hunting whale sharks, the largest species of fish on Earth. This graphic footage proves that whale sharks are a regular part of some orcas’ diets, and solves the mystery of how they are able to kill the massive fish.
On May 26, shark ecologist Kathryn Ayres was guiding tourists on an ocean safari near La Paz, Mexico when she saw a pod of orcas circling. “I knew some poor animal was being tormented,” Ayres said. “They like to play with their food.”
Along with photographer Kelsey Williamson, Ayres jumped in the water with her camera just in time to document five orcas taking down a juvenile 16-foot-long whale shark. Their video, published today in Frontiers in Marine Science shows the behavior in unprecedented detail.
Before now, only one other scientific report documented orcas eating a whale shark, videoed by sport fisherman further south in Mexico, but it didn’t detail the full predation sequence. Along with Ayres’s footage from this spring, the new research includes photos and videos of three other instances of orcas preying on these massive fish in Mexico’s Gulf of California. The first event in 2018 was caught on camera by a group of tourists planning to snorkel with sea lions on a rocky island north of La Paz. (They stayed in their boat once the attack began.) The second and third events were also captured by tourists in 2021 and 2023.
Now, with all these conclusive photos and videos, scientists can fully describe how the orcas take down the huge prey.
How orcas team up to hunt a whale shark
First, the orcas repeatedly ram a slow-swimming whale shark to stun it. When the fish loses its equilibrium, the orcas work together to flip it upside down to expose its unprotected belly. “You could hear the crunch of the final blow,” Ayres recalls, which incapacitated the shark. Next, the orcas bite off the whale shark’s pelvic fins, causing it to bleed to death. Then, they eat the fish’s organs, including its enormous fatty liver. It’s gruesome, and effective. Even birds capitalized on the feast, diving down for chunks of meat. “It was raining whale shark,” Ayres says.
A male orca named Moctezuma, first sighted in 1992, participated in three of the four recorded predation events. This male orca may be the son of one of the matriarchs of the pod, and perhaps learned his shark-eating techniques from her. He’s often joined by four or five female or juvenile whales who, in one recorded instance, initiated an attack without him.
This pod of orcas—dubbed the Moctezuma pod—seems to specialize in hunting cartilaginous fish. They also go after stingrays, pygmy devil rays, and bull sharks off the coast of southern Baja. (Moctezuma is named after the famous Aztec emperor. Females in the pod have also been given Aztec names like Quetzali, Niich or Waay, which means ‘witch’ in Majan since her dorsal fin is shaped like a witch’s hat).
This pod’s taste for whale shark might be unique. “I’ve never heard of whale sharks being targeted by orcas anywhere else in the world,” says Simon Pierce, a whale shark conservation specialist not involved in the study and the executive director of the Marine Megafauna Foundation. “But I can’t imagine a whale shark has much of a chance if a pod of killer whales zeros in on one.”