Last week, The New Yorker published a piece on how sound communication among fish is changing in order to overcome increased environmental noises. The article includes some great sound bytes to support the science!
In order to test how noise affects fish, Johnston and Holt captured blacktail shiners, a common type of minnow, from tributaries of the Chattahoochee River in Alabama. Male blacktail shiners make growling sounds when they’re courting a mate and knocking sounds when they’re being aggressive. Johnston and Holt transported the fish back to their lab, then placed two males and one or two females at a time into a tank outfitted with audio equipment. They played white noise through a speaker, alternating noisy periods—lasting between seventeen minutes and two and a half hours—with quiet ones. Then they analyzed audio and video recordings of the trials to see how the fish responded to the white noise. The researchers thought that the shiners might move closer together in order to hear one another better, but those results were inconsistent. “The other thing we thought they might do is shout—raise their voices,” Johnston said. “And that’s what they did.” During the noisy periods, the fish produced louder knocks and growls.