Orcas and dolphins team up to hunt salmon, stunning researchers in new B.C. study

What began as a routine study on how northern resident orcas forage for salmon turned into a remarkable discovery: orcas and Pacific white-sided dolphins cooperating underwater to hunt Chinook.

Researchers from Dalhousie University, UBC, the Leibniz Institute and the Hakai Institute were tracking orcas in the Johnstone Strait and Queen Charlotte Sound when dolphins unexpectedly joined the scene. At first, the team assumed the dolphins were simply interfering — but underwater tags, audio recordings and drone footage revealed something far more complex.

“We realized the dolphins weren’t freeloading,” said Sarah Fortune, lead author of the study. “They were diving deep, expending real effort. They were helping locate the salmon.”

How the partnership works

According to Andrew Trites of UBC’s Marine Mammal Research Unit, video showed orcas shadowing dolphins on long dives. Sound recordings revealed the whales going quiet, listening intently to the dolphins’ rapid echolocation clicks.

Dolphins spread out and scan wide sections of the water column — much broader than orcas can easily cover. When a dolphin locked onto a large Chinook salmon, orcas moved in for the kill.

“You can hear the crunch as the whale bites down,” Trites said.

The orcas then shared pieces of the salmon with their pod, while dolphins moved in to feed on the scraps — too large for them to capture alone, but perfect once broken apart.

“That’s their payoff,” Trites said. “Everyone gets to eat.”

A surprising lack of conflict

Despite decades of assumptions that dolphins steal food from orcas, the footage showed no aggression.

“The whales are huge. If they didn’t want the dolphins around, they’d make that clear,” Trites noted. “But they’re completely tolerant.”

Capturing “Orca TV”

Researchers used specially designed suction tags to gather hours of footage from the whales’ perspective. After each tag detached and floated to the surface, the team retrieved it and reviewed what they jokingly call “Orca TV.” Drone pilot Keith Holmes provided aerial confirmation of the unusual team hunting.

“At first we thought the dolphins were just interrupting,” Holmes said. “Then we saw coordinated foraging dives. It’s exceptionally rare to witness.”

A rare glimpse beneath the surface

Researchers documented 258 separate encounters of dolphins travelling alongside tagged orcas during the 2020 field season — a level of interaction seldom recorded between these species.

The findings impressed outside experts as well. Janie Wray, CEO of B.C. Whales, called the study “a missing piece of the puzzle” showing how different marine species cooperate in ways humans rarely see.

What comes next

Fortune says future work will explore whether certain family groups of northern resident orcas prefer hunting with dolphins — and whether these partnerships provide measurable health or survival advantages.

“Maybe the dolphins are more useful than we thought,” she said. “Don’t discount a dolphin.”