Massive creatures hunting sharks off Mexico create a ‘landscape of fear,’ study says

For the first time, killer whales have been documented hunting sharks in a small marine park off the coast of Mexico.

The newfound phenomenon could be creating a “landscape of fear” in the park — a hotspot of biodiversity — leading to dramatic changes in the region’s ecology, according to a study published June 4 in the journal Frontiers in Marine Science.

Between 2022 and 2023, three instances of orcas hunting sharks have been observed in the Cabo Pulmo National Park, which spans roughly 27 square miles in the Gulf of California.

While the behavior has been documented elsewhere in the gulf, it had never been seen inside the park’s waters, researchers said.

The first instance occurred in January 2022, when a drone recorded two orcas swimming near a blacktip shark.

“The shark immediately swam into deeper water, (presumably) after detecting the orcas,” researchers said.

The second instance occurred the same month, when a drone spotted three orcas perpetrating a “coordinated attack” on a bull shark. One orca charged the shark and attempted to hit it with its tail — a technique referred to as “tail-slapping” — but the shark dodged the attempt and escaped.

The third and final hunt took place in December 2023, when a drone recorded four orcas eating multiple bull sharks, researchers said.

Following at least one of the hunts, large aggregations of sharks disappeared from the area.

“This clear absence of sharks coincides with the presence of orcas in the park,” researchers said.

Additionally, groups of around 100 sharks were seen further south in the park near a reef break, which is inaccessible to orcas, indicating the sharks were seeking out refuge.

“Our results therefore suggest that orcas could be in the process of creating an ecological ‘landscape of fear,’” researchers said.

The orcas’ newly documented hunts in the park could potentially lead to a “dramatic” displacement of sharks — which are a key element of the park’s tourism industry. Fishing was banned in the park in 1995, leading to an abundance of marine life, including sharks, and drawing scuba divers from around the world.

However, researchers noted, it’s not clear how long orcas had already been preying on sharks in the region as the animals are understudied, and their reliance on sharks has likely been understated.

But now, thanks to the increase in the use of cameras, drones and “citizen scientists,” the orcas’ activities are more accessible to humans.

This story was originally published June 18, 2024 at 1:03 PM with the headline "Massive creatures hunting sharks off Mexico create a ‘landscape of fear,’ study says."