How Fish Noises Can Help Manage Species

Imagine the sound a haddock might make to communicate underwater. If you’re thinking it sounds like a Harley revving up its engine, you’re pretty close.

Rodney Rountree, a marine biologist based at the University of Massachusetts Amherst, studies the noises fish make. He said the sounds are key to understanding fish behavior and could even help us protect many species from overfishing.

Rountree does a lot of his research by tuning in to fish around Cotuit Town Dock on Cape Cod. He leans over the edge of the dock to drop a set of underwater microphones down to the seafloor. These hydrophones channel fish chatter directly into his laptop.

According to Rountree, a lot of fish make noise to call out to each other.

“Some of the calls, like the toadfish and the cusk eel calls, are advertisement calls," he said. "They’re calling for a female."

The term makes sense. Fish use "advertisement calls" a lot like listings on online dating sites.

“The female actually can get a lot of information from the call,” Rountree said. “She can tell roughly what size the fish is, and there’s some indication that they sometimes get information about the sexual fitness of the animal, so [questions like] 'Is it going to be a good mate, that’s going to have good offspring?' ”

Fish like cod and haddock send out advertisement calls, but they also make distinct sounds while spawning.

Rountree has recorded haddock making babies as boats buzz in the background around the Cape. He said that by mapping out breeding grounds by the sound of fish spawning can give fishermen guidance on areas to avoid during mating season. That would give species threatened by overfishing the chance to make a comeback through re-population. Managing fisheries this way can help the fishing industry in the long run, Rountree said.

“Most fisherman are actually very conscious of their impact on the ocean, and if they understand that fishing along a spawning aggregation is going to be detrimental to their fishery, then they may want to avoid that just as much as anybody else,” he said.

But it’s going to take time before fish sounds can be used to manage fisheries. Rountree is trying to identify as many fish by their calls as he can. His equipment picks up all sorts of thumps and grunts — and even a few farts.

There are also some fish sounds he can't identify.

Rountree spends hours logging audio and comparing it to images of fish captured on an underwater camera. It's drudgery, but he said the thrill of discovering new fish calls keeps him tuned in to the sea.