Orcas and Dolphins Glimpsed Fishing Together for Salmon

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DOlphins, with their exceptional echolocation abilities, are adept at catching fish. But some fish, like Chinook salmon, are too large to capture and swallow whole.

In the first recorded case of hunting cooperation between dolphins and orcas, a new study published today in Scientific reports describes how dolphins benefit from associations with orcas, who capture Chinook salmon, carry them to the surface, and break them into smaller pieces.

Killer whales (Killer whale) that live along the coast of British Columbia feed almost exclusively on large adult Chinook salmon, which can weigh up to 30 pounds. Groups of Pacific white-sided dolphins (Lagenorhynchus obliquidens) have been observed swimming near killer whales. An individual dolphin requires about 20 pounds of food per day, a daily diet that marine mammals typically supplement with smaller prey, such as sardines, herring and capelin.

Since dolphins and killer whales are known to use coordinated hunting strategies to herd and capture their prey, scientists thought their proximity off the coast of British Columbia was a coincidence. Perhaps the groups of killer whales and dolphins both focused on areas rich in fish, but did not compete with each other due to their distinct diets, the researchers reasoned.

But the team was surprised when they spotted nine killer whales around Vancouver Island. By collecting data using a variety of methods (aerial footage from drones, photographs from the research boat, custom multisensory tags capturing 3D dive data while recording vocalizations, and collecting underwater video from the whales’ perspective), researchers learned that killer whales frequently followed dolphins.

Read more: »The story of a lonely orca»

In total, scientists recorded 25 cases of killer whales changing course after encountering dolphins. Four of the killer whales tracked, as well as three untagged whales, were recorded interacting with dolphins. When killer whales captured and shared Chinook salmon among themselves, dolphins stayed nearby, in at least one case feeding on the fish scraps. There was no evidence that the killer whales were trying to prey on the dolphins.

The dolphins appeared to be getting a free meal and perhaps protection from other groups of killer whales, which sometimes prey on the dolphins.

But what could orcas gain from such a cooperative hunting strategy? In the article, the study authors hypothesize that this arrangement “could improve the ability of killer whales to detect Chinook.” When the killer whales changed course to stay near the dolphins, they could have listened to the dolphins’ echolocation. Killer whales also emit echoes while hunting, but two sets of echoes may be better than one for locating targets.

Further study could confirm whether this is truly a cooperative hunt.

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Main image: Courtesy of the University of British Columbia (AT rites), Dalhousie University (S. Fortune), Hakai Institute (K. Holmes), Leibniz Institute for Zoo and Wildlife Research (X. Cheng)

• Devin Reese

  Published on December 11, 2025

  Devin Reese is the editor-in-chief of Natural history and a science writer based in Alexandria, Virginia.