'Talking fish' not heard by conservation policies, SFU study warns

More than a thousand fish species use sounds to exchange information, attract mates, and avoid predators through hums, grunts, clicks, and bubbles. Yet, the vital role of fish sounds—and the impact of noise pollution on the fishes that produce them—are left out of critical conservation policy, says study led by marine ecologists at Simon Fraser University.

The ocean is filled with the bustling sounds of daily marine life, including the sounds made by soniferous fish species. These sounds aren’t merely passive sounds—soniferous fishes produce sound themselves, like a whale ‘singing’ through vocalizations, says Kieran Cox, Liber Ero and NSERC fellow at SFU and co-founder of FishSounds.net. 

Yet, a new study published in Biological Conservation found that over the last two decades, only two Canadian marine assessments of sound-producing fish species that are at risk of extinction even addressed soundscapes, sound production, or noise pollution, and neither of those assessments considered all three together.  

“Active sound production is key to many fish behaviours, including reproduction. 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,” says Cox, the study’s senior author. 

Marine noise pollution from commercial shipping, resource extraction and military and industrial activities, for example, is known to impact individual fishes, which can translate to bigger population impacts.  

“If fish can’t attract mates, their ability to reproduce can decline, and the size of the population could be reduced,” adds Kiara Kattler, who led the study while working in distinguished professor Isabelle Côté’s lab at SFU.

The best way to mitigate the negative impacts of marine noise pollution on soniferous species is to include fish acoustics in federal conservation strategies, Cox says, which means getting this issue on one key radar: the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).  

COSEWIC is an independent expert panel that advises the Minister of Environment and Climate Change on the status of threatened wildlife. Their recommendations have strong influence over potential listings on the Species at Risk Act (SARA), the federal legislation to protect threatened species from extinction.  

Of COSEWIC and SARA’s 374 assessments and status reports and recovery action plans on at-risk marine and freshwater fishes investigated in the study, not a single SARA document mentioned sound production, soundscapes or the potential threat of noise pollution to population recovery. Just one COSEWIC assessment acknowledged a species as actively soniferous. 

“We know that protecting communication spaces for larger, more charismatic marine mammals works. It has been critical for the conservation of the southern resident orcas,” says Cox. “Sound and noise are as crucial for fish as they are for whales, and they should be equally protected.” 

Noise pollution and the value of sound

Sound has several key elements to consider, says Kattler. One is occurrence, or how often and for how long a species will be exposed to it. Another is pitch: how high or low is the frequency of the sound. Then there is how loud the sound is.  

“These three aspects of sound create different types of marine noise pollution,” Kattler says. "A sound could be loud and high-pitched for a very short time, or quiet and low-pitched for a long period of time. Each kind of noise pollution poses potential risks to marine species, from whales to fish to crustaceans.”

It may also be that the deeper you go in the ocean, the more critical sound communication becomes.  

“We have some early evidence to suggest that sound-producing fish are more common at deeper depths,” explains Cox. “As light is limited in the deep ocean, we believe that the importance of using sound to communicate increases,” a finding that emerged in another recent study on the impacts of deep-sea mining.