Knock, knock, who’s there? B.C. biologists identify unique sounds of 8 fish species

A copper rockfish swims near an underwater microphone device in this undated handout photo. THE CANADIAN PRESS/Handout, Shane Gross

There are grunts and growls, knocks and croaks — but the wild sounds detected by a team of British Columbia researchers don’t belong to any of the province’s famous forest creatures.

The noises are made by fish off coastal B.C., and the biologists say they have identified the unique sounds made by eight different species.

The University of Victoria researchers used an underwater microphone to eavesdrop on rockfish and other species near the community of Bamfield in Barkley Sound, on the southwest coast of Vancouver Island.

They developed a machine learning model that examined the unique characteristics of the fish noises, and were able to differentiate those made by separate species — including those that are closely related — with high accuracy.

“This research project was really exciting,” said Darienne Lancaster, the University of Victoria PhD candidate who led the project. “Some of (the fish) have never been recorded as making these sounds before.”

The research was published last month in the Journal of Fish Biology.

They identified sounds for black, quillback, copper, canary and vermillion rockfish, as well as ling cod, kelp greenling and pile perch that commonly occupy B.C.’s rocky reefs.

Researchers listened to the knocking and grunting noises the fish made to see if they could pinpoint them to the exact species.

Some species’ grunts sounded more like croaks or growls, and identifying sound characteristics like length and frequency helped separate the noises made by different fish.

Lancaster said identifying the unique sounds made by the fish could help scientists understand more about their behaviour.

The team recorded video of the fish, and when paired with the audio recordings they saw a connection between the sounds the fish made and their actions that followed.

For example, some fish, like the copper rockfish, made knocking sounds while they chased prey along the ocean floor, but sounded different when it was them being hunted.

“We learned that both copper and quillback rockfish make a lot more grunting type sounds when they’re running away from predators,” Lancaster said.

She said that while her research project identified sounds for eight species, there are dozens more that could be identified off B.C.’s coast, including 41 species of rockfish.

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Lancaster said if researchers can tell which fish species are in an area based on the noises they make, it could help conservation and fisheries monitoring efforts in the province, by identifying the presence of certain fish without having to catch them.

“We can just go out, have a fish sound detector, and know that there’s, say, eight different species in that particular location. And that’s really important because then we can start to make conservation objectives like marine protected areas for those very vulnerable fish species,” she said.

Her team wants to create a “fish sound detector” to tell which fish are in a certain area based on acoustic data, which could help track changes in fish populations, she said.

They also plan to research in different regions of B.C. to see if fish have a different “accent” or “dialect” depending on their location.

“I think this project is really important for people in B.C. and just (fish) management in general along the B.C. coast,” Lancaster said. “If we can go out and put a simple microphone down in the water and know what species are living there, it’s a really great non-invasive way to start to count these fish.”

This report by Marissa Birnie, The Canadian Press, was first published Jan. 9, 2025.