Southern Resident killer whales live in one of the noisiest stretches of ocean on the Pacific coast. Within this region, Boundary Pass and Haro Strait — key Salish Sea channels and core habitat for killer whales — form the primary maritime gateway to and from the Port of Vancouver, one of Canada’s largest and busiest ports. Every cargo ship, tanker, ferry, and recreational boat that transits these waters contributes to an underwater soundscape that the whales must navigate to find food, communicate with family members, and survive.
“We’ve known for years that underwater noise is a problem for killer whales. What we didn’t have, until now, was a detailed, decade-long picture of how much things have changed, or a rigorous assessment of whether current management measures are making a difference”, explained Dr. Valeria Vergara, who runs Raincoast’s Cetacean Conservation Research Program.
Tracking acoustic change
Underwater acoustic data have been collected from two hydrophones deployed in strategic locations within killer whales’ habitat in the Salish Sea. The Saturna Island Marine Research and Education Society (SIMRES) has maintained a hydrophone off Monarch Head, Saturna Island, since 2014, and Raincoast Conservation Foundation deployed a hydrophone off Wallace Point, Pender Island, in October 2023. Both underwater microphones are located directly within or near the Pender and Saturna Vessel Restricted Zones in the Salish Sea. These are designated areas where vessel traffic is seasonally slowed or restricted to reduce underwater noise and protect endangered Southern Resident killer whales.
Dr. Valeria Vergara and Dr. Lance Barrett-Lennard, Cetacean Conservation Research Program Directors at Raincoast, prepare the Pender hydrophone for deployment. Photo by Alex Harris.
The acoustic analysis, conducted by SoundSpace Analytics, compared underwater noise in 2017, 2023, and 2025 using different measures. One key metric, “Listening Space Reduction”, estimates how much of killer whales’ acoustic habitat is blocked by vessel noise at any given time, while “Quiet Time” measures the rare moments when the whales can communicate without interference.
