Francis Juanes pumps up the volume on fish
September 19, 2024
Award-winning biology professor Francis Juanes has been making a splash.
Although he’s not a fisher himself, the Liber Ero Chair for Fisheries Research has studied aquatic animals – in particular their ecology and dynamics – for most of his career. He started with capelin in Newfoundland one summer during his undergraduate program, detoured to Dungeness crabs while in graduate school and then, as a PhD student, fell under the spell of bluefish.
“That’s what did it,” he says. “I was hooked.”
The only species in its family, bluefish are very aggressive and fast growing. A salt-water fish, it lives in estuaries when it’s small. It’s found worldwide and prized by fishers everywhere it exists.
There’s a lot going on under the surface. And that’s where Juanes has continued to explore both literally and metaphorically, where people once hadn’t even looked. Or rather, listened.
His research on the plainfin midshipman, a smaller fish that ranges from the deep ocean to intertidal zones in the spring, is the most novel and perhaps the most impactful.
Twenty years ago, Juanes began using hydrophones to capture sounds underwater and video cameras to identify which animals were making which noises.
“Humans don’t hear very well under water,” Juanes says, “so we thought the oceans were silent. They’re not. They’re full of sounds.”
Male midshipmen, for example, make a nest on the shore below the high-tide line and then call to the females using sonic muscles around their air bladders like they’re playing the drums.
“Here on the west coast we have ferries, recreational fishers and an increasing number of tankers,” he says. “On the east coast there’s oil and gas exploration and construction. And now there’s more shipping in the Arctic as well; that’s going to affect marine mammals and important fish species like Arctic cod.”
What happens, Juanes wondered, when there’s a lot of ship traffic? What’s the effect of noise on a species, like the midshipman, that depends on vocalization?
He identified what’s now called the Lombard or cocktail-party effect. Like people in a loud environment, the fish must sing louder and at a different frequency in order to be heard.
Comprehensive as his fish-sounds research continues to be, half of his 40-person lab is dedicated to salmon ecology. In one current project, his team is trying to understand why the survival rate for hatchery-reared salmon is lower than natural-origin salmon once they are released from hatcheries. One possible explanation is that hatchery rearing leads to a malformation in their earbones which likely affects their hearing, leaving them vulnerable to predators and unable to keep track of their schoolmates. But—and this is yet another reason for Juanes’s honours and recognitions this year—he doesn’t stop at identifying the problem. He also figures out a solution and, crucially, shares it widely. Experiments showed that living in round tanks and swimming in one direction for long periods of time can lead to the observed abnormalities. Periodically reversing the flow of water appears to remove the effect, leading to more normal earbones. He hopes that these results can lead to changes in how salmon are reared in hatcheries.
Juanes’s outstanding salmon and marine ecology research, community engagement and policy impacts earned him three prestigious awards in 2024.
The Confederation of University Faculty Associations of BC honoured him with the Paz Buttedahl Career Achievement Award to recognize his life’s work conducting fundamental and innovative research in fisheries ecology. Juanes has transformed the way that scientists model fish population dynamics and he has pioneered research in soundscape ecology. He established bioacoustics as a novel approach to ecosystem health. And CUFA BC also specifically recognized that inspiring new generations of leaders and policymakers in the field of fisheries ecology is one of his major achievements.
Next up was Fisheries and Oceans Canada’s Timothy R. Parsons Medal. Nominator Mark Lewis, Gilbert and Betty Kennedy Chair in Mathematical Biology, wrote that Juanes’s fundamental and innovative research in fisheries ecology has advanced ecological theory, and has filled significant gaps for management agencies nationally and internationally. His team has been pivotal in quantifying how individuals, populations and communities respond to environmental and anthropogenic changes. And again, Lewis says, Juanes places particular emphasis on communicating groundbreaking results with the public and management agencies.
Then came the Award of Excellence from the American Fisheries Society, of which he is a long-standing and active member. The award, presented at the AFS’s 154th Annual General Meeting on September 16, also honours Juanes’s contributions to science, knowledge mobilization and the next generation.
Juanes continues to propel fisheries research.
“There are about 30,000 species of fish,” he says. “There’s immense variety. Every fish has a story that’s interesting and so much is still unknown.”