Orcas and Dolphins Cooperate to Hunt Chinook Salmon Off BC

In a groundbreaking observation off the coast of British Columbia, northern resident killer whales, also known as orcas, have been documented for the first time cooperating with Pacific whitesided dolphins to hunt Chinook salmon. The interactions, captured in August 2020 near Vancouver Island, reveal an unlikely alliance between the two marine predators, suggesting mutual benefits in foraging during seasonal salmon migrations.

Researchers from Dalhousie University, along with collaborators from the University of British Columbia, the Leibniz Institute and the Hakai Institute, tracked nine orcas using a combination of drone footage, underwater cameras, acoustic recordings and tags attached via suction cups. The tags, which recorded video, sound and dive data up to 60 meters deep, provided rare insights into the underwater dynamics. In 25 instances, orcas altered their course after encountering dolphins, following them on foraging dives toward schools of Chinook salmon, which can exceed one meter in length and are too large for dolphins to capture whole.

The study, published in the journal Scientific Reports, details how orcas caught and tore apart the salmon at the surface to...