Fish can breathe under water. They’re great swimmers. But they’re not really known for their singing.
But they do sing – kind of. And now scientists on the Texas Gulf Coast are hoping that fact can help sustain their populations.
The research started on a different coast, in the Gulf of California. That’s where Gulf corvina crowd a single estuary every year to spawn. As part of the ritual, the males let out a thunderous croaking chorus.
“It kind of sounds like static but very noisy static,” says Brad Erisman, assistant professor of fisheries ecology at UT-Austin. That static is the simultaneous croaking of, in some cases, up to a million or more male Gulf corvina, he says.
"It's so loud that it makes it difficult for fishermen or anyone on the boats to actually have a conversation,” Erisman says.
But it makes it really easy to catch the fish in big nets. That can lead to overfishing, so fisheries managers set limits.
“Not only are managers worried, but fishermen are worried and researchers like us are worried because we’re not sure whether they’re setting the limits at a sustainable level,” says Timothy Rowell, a PhD student at Scripps Institution of Oceanography who recently published a paper with Erisman on the corvina.
The challenge for Erisman and Rowell was to figure out how many corvina there are to make sure they’re not being overfished. The answer: use the fish’s sounds to take the census.
The researchers put microphones in the water to record the corvina and used sonar to verify the number of fish.
“If they correlate, that means you should be able to use sound to estimate how many fish are present,” Erisman says.
And it worked. The implications for fish research are big.
“You could put underwater microphones called hydrophones throughout a wide region,” Rowell says. “So you could monitor a wide area at multiple locations at the same time, instead of just being at one spot at one time.”
Researchers will be working in Port Aransas, Texas, this summer to find out if the same approach can be used to monitor sea trout.