While a two-year-old can probably tell you what sound a dog or a cat makes, she might be stumped if you ask, what sound does a fish make?
But that is what Ana Širović, an oceanographer at the Marine Bioacoustics Lab at Scripps Institution of Oceanography, is trying to find out.
"Everybody knows that whales make sounds, that seems to be common knowledge, but usually when I tell people I study fish sounds they give me strange looks," she said.
Fish make sounds by oscillating their swim bladder, or by rubbing the bones where their fins attach to the body, similar to how crickets make sound by rubbing their legs, she said.
Širović and her team of researchers have been recording sounds in the kelp beds off La Jolla Shores for two years. But there was a problem — they did not know what fish were making what sounds.
"One of the challenges in this work is that when we record sounds in the ocean, we don't always know what it is that is producing those sounds," she said.
So they built some new equipment: four underwater microphones coupled with a camera.
"So we can localize each sound we record, we can determine the location, where it is, and then we can look at the camera picture that we have to see what was in that area," she said.
The team has been using the new equipment at La Jolla Shores since last summer, and earlier this month tested it out in the kelp tank at the Birch Aquarium. The tank helps Širović narrow down what fish might be making noises since there are a limited number of fish species in the tank.
The goal of this research is to be able to identify fish by their sounds, which can ultimately help scientists learn where fish gather and breed, and it would allow policymakers to decide what marine areas should be protected, Širović said.
For example, fish are known to make sounds during spawning, when defending their nest or territory and in other social interactions, she said.
"Then we can learn something about what areas these fish find important and where they gather to do these biologically important functions," she said.
Plus, she might be able to help two-year-olds of the future answer the important question of what does a fish say.
