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While many animals are commonly known to communicate using sounds, fish aren’t usually among them. While we’ve known for thousands of years going back to Aristotle that some fish make sounds, they were thought to have been the exception rather than the rule.
A new paper published in the journal Ichthyology & Herpetology challenges that notion, providing evidence that a large swath of fish communicate using sounds, through methods which evolved at least 33 distinct times over the last 155 million years. Aaron Rice, a researcher at the Lisa Yang Center for Conservation Bioacoustics at Cornell University was the lead author of the paper and spoke with SYFY WIRE about the findings.
The team scoured countless existing papers and recordings to compile a comprehensive accounting of acoustic behavior in fish. Their work focused primarily on ray-finned species, of which there are more than 34,000 known.
“Fish is a problematic term because it basically groups together organisms that don’t’ share a common ancestor. When we think of fish, we typically think of ray-finned fish,” Rice said.
Examining the records for all 34,000 species was a larger job than the team was prepared to undertake, so instead they look at family groups to see if records existed, and if so, how the sounds were being created and to what ends. They found a number of adaptations which allow fish to make sounds without the advantage of vocal cords.
“They can grind their teeth or make movement noise in the water, and we do see a number of specializations that are involved,” Rice said. “Probably the most common adaptation are muscles associated with swim bladders. In fact, the swim bladder muscles of the toad fish are the fastest contracting vertebrate skeletal muscles. These are high-performing adaptations.”
Rice and colleagues found that sounds were created under a number of different behavioral contexts which are similar to those seen in other animals, and in humans. Common among these are sounds related to reproduction, used to coordinate the release of genetic materials or attract mates. It’s been said that there are plenty of fish in the sea and listening to their conversations tells us that they’re all ready to get busy.
In addition to reproductive communication, fish commonly make what are known as antagonistic sounds in an effort to defend either a food source or territory. Lastly, fish also make social calls essentially calling to peers to see if they’re around.
The encyclopedia of fish language, as far as we can tell, is filled with variations on “get away from me,” “get closer to me,” “don’t touch my food,” and “is anybody out there.” These behaviors, however, aren’t universal across the various species or families. The body of evidence suggests instead that some fish are more talkative than others. The team found a strong correlation between the density of a particular environment and the level of sound communication happening. Those fish which live in coral reefs or in the Amazon River, the fish equivalents of the big city, are more likely to talk than more solitary fish.
“Every toadfish we looked at seems to make lots of different sounds. Catfish make tons and tons of sounds. Piranhas, tetras, groupers, there are a number of lineages across the fish family tree that produce lots of sounds,” Rice said. “There are other groups that are more on the quiet side.”
While this study provides evidence that fish are more communicative than we ever gave them credit for, Rice allows for the possibility that they talk even more than we now know. Because the study was a meta-analysis of existing literature, a lack of evidence of acoustic behavior in a particular family or species doesn’t necessarily mean they are silent. It could be that there’s simply a gap in the data.
“In my lab on campus I have a ton of fish tanks set up with fish that I’ve picked which have specifically never been recorded before, to see if we can get sounds out of them,” Rice said. “The question is, are they making sounds and they’re just overlooked, or are they really silent?”
The search for additional aquatic communication among fish continues apace and understanding these relationships might be more important than ever. Rice makes reference to previous movements to address noise pollution for the benefit of dolphins and whales and indicates that the same concerns are likely true for a majority of fish in oceans and other bodies of water.
A better understanding of how fish communicate, and how our activities might impact their ecosystem, allows us to make informed decisions about wildlife management. The fish are telling us what they need, it’s up to us to listen.