People aren’t the only ones who raise their voices at each other; fish can shout, too. After catching some blacktail shiners—little minnows characterized by a big black splotch on their tail fin—fishery biologists placed them in tanks equipped with underwater speakers to see if noisy conditions affect communication.
While females of Cyprinella venusta (pictured) don’t make noise, males produce two types of sound: growls and knocks. The growl is similar to a cat’s purr and is made when courting a female, while the knocks are more like popping sounds, typically made when males are fighting or defending their nests from another male.
After recording these natural sounds during quiet periods, the researchers played white noise in the tanks. As they raised and lowered the volume of the static, they observed that rather than get closer together and continue on at the same “speaking” level, the blacktail shiner stays put and amps up its own voice to be heard.
The study, published this month in Behavioral Ecology, is the first to find that fish will tune up their vocal volume in response to elevated noise. As noise levels around rivers continue to rise with cars thundering across bridges and boats chugging on the water, the researchers suggest more needs to be learned about how fish are responding to louder environments, and whether they’re getting stressed and behaving differently.