Fish have voices but conservation policies ignore them

Fish have voices, and the sea is never silent. From croaks that ricochet through mangroves to deep‑sea booms, these conversations guide courtship, navigation, and survival.

A new analysis from Simon Fraser University shows that Canada’s flagship conservation policies almost never recognize those voices, leaving vital acoustic habitats unguarded.

Marine ecologist Kieran Cox of Simon Fraser University co‑authored the study that sifted through two decades of federal paperwork.

Fish use sound to survive and reproduce

More than 1,000 known fish species are soniferous, meaning they deliberately produce sound to communicate, and hundreds more are suspected to do the same. Male toadfish drone like idling motorcycles, while haddock tick and grouper boom, each signal tuned to species‑specific ears.

“A male fish might hum or sing to attract their mates, and the longer his song, or the louder it is, the more eggs he will get from females,” explained Cox.

Atlantic cod Gadus morhua grunt through swim‑bladder muscles during spawning, and researchers have tracked entire aggregations by listening to those calls.

Ocean noise drowns out fish voices

The ocean soundscape, the mix of biological, physical, and human noises filling the water, has changed faster than any other habitat feature in recent decades.

Ship engines, seismic air guns, and pile drivers add low‑frequency roar that travels farther than light or chemicals, masking the fine‑tuned signals fish depend on.

Most of this din comes from underwater radiated noise generated when propeller bubbles collapse and machinery vibrates the hull. As depth increases and daylight fades, sound replaces vision, so the risk rises for deep‑water species that have no other way to find mates or food.

Conservation laws ignore acoustic habitats

COSEWIC, the expert panel that advises Ottawa on endangered wildlife, acknowledged fish sound production in just one assessment out of 204. Neither of the 56 recovery strategies drafted under SARA, Canada’s endangered‑species law, mentioned soundscapes or noise threats.

Anthropogenic noise has doubled background sound levels in more than half of U.S. protected areas, hinting at the scale of the problem in Canadian waters as well.

When noise blocks communication, the effect mirrors habitat loss, shrinking a fish’s functional living space even though the water looks unchanged.

Learning from the whales

Regulators already protect communication spaces for southern resident killer whales, setting vessel speed limits and buffer zones in the Salish Sea. During voluntary slow‑down trials, quieter ships raised successful foraging dives by the whales, proving that less noise can yield instant biological payoffs.

Fish biologists argue the same principle should apply below the whales, because many coral, seagrass, and deep‑sea communities are built on acoustic cues.

The International Maritime Organization’s revised guidelines outline hull forms, propeller tweaks, and resilient engine mounts that slash cavitation clatter at the design stage.

For existing fleets, slower speeds remain the quickest fix, trimming hull noise in minutes and saving fuel at the same time. On land, urban planners already impose airport curfews; similar acoustic zoning could shield key spawning refuges from seismic blasts.

Fish voices must be included in planning

Ecoacoustics, the cross‑disciplinary science of environmental sound, now lets managers deploy autonomous recorders that log fish choruses year‑round with little labor.

Cox and his team want Ottawa to add acoustics to every new status report, a change that would trigger legal duties to weigh noise limits before approving coastal developments.

“These three aspects of sound create different types of marine noise pollution, and each kind of noise pollution poses potential risks to marine species, from whales to fish to crustaceans,” said Kiara Kattler, who led the analysis in Isabelle Côté’s lab.

If policy follows the evidence, tomorrow’s endangered‑species plans could include quiet hours, ship‑route changes, and protected “singing grounds” for fish.

What policymakers can do now

Fisheries managers don’t have to wait for more studies to take action. Passive acoustic monitoring gear is already cheap, easy to deploy, and able to track seasonal behavior in many key species.

Adding simple guidance on soniferous species to existing review checklists could prevent new development from degrading acoustic habitats by accident.

Acoustic degradation doesn’t only affect fish. Crustaceans, cephalopods, and even coral larvae also use sound to find mates or settle in reef habitats, which means entire ecosystems could be thrown off balance.

By integrating sound into conservation policies, agencies could protect dozens of marine species at once without needing separate rules for each.

The study is published in the journal Biological Conservation.

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