Scientists and anglers have long known that the toad and a handful of other fish species like catfish are quite talkative. But new research reveals that the ability to make sounds is a much more common trait in fish than previously thought. It turns out that nearly 29,000 species are likely to have the ability – with big implications for what we know about their lives.

“What our study shows is that with [fish sound production] being prevalent, it’s starting to reframe the way we think about the sounds of the ocean,” says Aaron Rice, lead author of a new paper in the journal Ichthyology & Herpetology and researcher at the K. Lisa Yang Center for Conservation Bioacoustics at the Cornell Lab of Ornithology. It turns out that the clamor of the underwater world is probably as diverse as it is in rainforests and wetlands.

The researchers conducted an analysis at the family level rather than the species level, using primarily acoustic recordings, knowledge of fish anatomy, and historical descriptions of fish sounds recorded by naturalists dating back to Aristotle. Lacking vocal cords, fish make noise either by using their muscles to vibrate or drum their swim bladders (the gas-filled organs that help them swim at different depths without floating or sinking) – the most common method of production of sound – or by rubbing parts of their skeletons together. Rice and his co-authors found that these abilities independently evolved at least 33 times within the fish class. This tells us, says Rice, how “important” sound communication can be for fish, “and that there is very strong selection pressure to use sound.” That is, factors such as predation or food availability meant that, for many species, fish capable of producing sound had a better chance of survival.

Although many fish sounds have yet to be recorded, Rice has compiled a database of existing recordings over the past two decades. “It started as a side project and then became kind of an obsession,” he says. He’s excited to see similar efforts happening elsewhere, like the Global Library of Underwater Biological Sounds (or GLUBS), an international initiative to collect sound recordings of marine life on an open-access web platform. . “Certainly in the birding literature, there are these wonderful onomatopoietic descriptions of what different birds sound like. There are lots of bird song CDs,” Rice says, “but nothing comparable. really existed for fish, and now there’s this revolution in the world of underwater acoustics that’s really bringing that focus back to fish and I think that’s really exciting.

The new study also raises some concerning questions. If sound communication plays a role in how so many fish reproduce, defend resources, or avoid predators, then, says Rice, “the widespread extent of human noise pollution in the oceans may actually have serious consequences. on what this means for fish ecology. “The most pervasive source of noise is of course shipping traffic, but other noises such as long-range military sonars, tidal and offshore wind turbines and seismic surveys for oil and gas exploration add to the cacophony beneath. -Marine. The impact of this racket on marine mammals, including hearing loss, stress and avoidance of noisy areas, is well documented, but what do we know about what it does to fish?

A 2018 review of 115 studies of human-made underwater noise pollution lists a long list of harms to dozens of fish species, including “communication, orientation, feeding, parental care and detection of compromised prey, as well as increased aggression”. It can also “lead to less group cohesion, avoidance of important habitats, fewer offspring, and higher mortality rates. . . poor growth rates, decreased immunity and poor reproductive rates”, as well as hearing loss and abnormal anatomical development. To take a specific example, when exposed to boat noise, toads – like those that disrupt the Sausalito houseboat community – struggle to communicate and find optimal mates, limiting reproduction and potentially affecting populations. whole.

How do fish cope with increasingly noisy waters? We know that birds turn up the volume and pitch of their songs to be heard above traffic noise, but Rice says fish “don’t seem to have the same level of plasticity.” He wonders if many fish populations have become ‘habituated’ to increased noise pollution, and if there are ‘chronic, sub-lethal impacts on these populations from increased ocean noise’.

Although noise pollution is already pervasive in the ocean, it could get even worse and reach new depths as marine industrialization increases, including through deep-sea mining. “We know so little about these deep water areas,” says Miyoko Sakashita, who advocates for better legislative protection of marine life as director of oceans at the Center for Biological Diversity. “But it does appear that the mining itself, which is just scraping the ocean floor, will not only be noisy, but will also destroy these deep-sea habitats.”

Currently, there are no international regulations on ocean noise pollution, although there is legislation to tackle the problem at national and regional levels, such as the Union’s Marine Strategy Framework Directive European Union and the Marine Mammal Protection Act in the United States. The latter, says Sakashita, “is the one that has been most exploited to control noise from activities such as sonar and seismic.” In his view, the new evidence that fish acoustic communication is a common trait “could be important for increasing noise regulation.”

NGOs and researchers offer a number of options for reducing ocean noise. For example, measures for ships could include technological changes and reduced ship speeds. For an activity like pile driving – used to erect offshore wind turbines – sound barriers could be placed around the piling operation, while fewer and larger turbines could be installed to reduce the amount of pile driving necessary.

Noise isn’t the only threat to sonic fish. The rate at which fish — being cold-blooded — contract the muscles around their swim bladder to produce sound, Rice explains, “is directly related to water temperature.” As the water warms up in the spring and summer – fish breeding season – the fish begin to make higher pitched noises. As climate change raises average ocean temperatures and causes more frequent and severe marine heat waves, the question, says Rice, is what “persistent and directional change” in water temperatures might mean. for the fish?

In other words, if the oceans are constantly getting warmer, will the fish continue to raise the pitch of their cries, how will this affect things like reproductive success, and will they be able to s ‘adapt ? New research modeling how climate change will affect sound transmission in the oceans adds another dimension to this concern; sound travels faster in warmer waters, and there are certain “acoustic hotspots”, identified in the research, which will experience significant variations in the speed of sound later in the century due to climate change, with potentially significant impacts on species in these areas.

The growing evidence of sound production by fish can certainly help scientists assess the health of underwater ecosystems. “Being able to imagine whether it’s a coral reef, a sandy bottom, an estuary or a river, because these vibrant, noisy places filled with the sounds of fish, that’s what they should be like” , says Rice. “[S]ound is really an essential part of these ecosystems, and something we should pay attention to.

These sounds, like the hum of the amorous toad, are not always as musical as the more familiar bird songs. But as the houseboat dwellers of Sausalito demonstrated when they started the Humming Toadfish Festival in 1988, fish chatter is something people could also learn to love and celebrate.