Fish talk. And often they talk about sex.
Of course, they don’t “speak” in words because they don’t have vocal cords.
Rather, they are “soniferous,” meaning they make sounds. They use their teeth, bladders, and other means to grunt, croak, click, drum, and squeak, saying things like “Swim over here, fishy, fishy” and “Get outta here, you fat flounder. This is my nest.”
Up to 1,000 species of fish are believed to be chatty and, yes, the sunfish family, which includes bass, is in the conversation. In fact, hydrophones were used to study bluegill courtships sounds more than 40 years ago.
“Some centrarchids do make noise,” said Gene Wilde, professor of fish ecology at Texas Tech. “But it seems to be only during breeding season, and we’re not sure how they do it. Possibly by rubbing mouth parts together.
“Some species make sounds year around,” he added. “But most fish sounds are associated with breeding. For example, drum attract mates that way.”
The gizzard shad, an important forage fish, is one species that makes sounds year around, and what a Texas Tech graduate student recently discovered about those sounds when the fish are exposed to environmental stressors is significant.
“Gizzard shad are widespread, in about 2/3 of the country,” said Matt Gruntorad. “They produce calls when stressed, and these calls could be an early warning system when there’s a (water quality) problem. They could help protect valuable game fish and water supplies.”
The Texas Tech researcher exposed the shad to various levels of salinity, pH, and toxicity (ammonia hydroxide). As levels increased, the fish became louder--- up to a point. At the highest levels, they were quieter. “There could be a threshold when they are too stressed to make sounds,” Gruntorad said.
Sounds made by fish of 2 inches or so were too soft to analyze. But 12-inch shad yielded strong signals for the hydrophones.
Even so, though, their calls would be difficult, if not impossible, for the human ear to detect.
“They don’t croak,” the graduate student said. “Their calls are very simple, very quiet. They release gas through the anal duct. It’s like a fish fart.”
Compared to saltwater, much work remains to be done to recognize and understand sounds made by fish in freshwater, Gruntorad said.
Wilde agreed, adding that drum make their unique sound by playing muscles against their swim bladders, while catfish create their characteristic “grunts” by rubbing the pectoral spine against the pectoral girdle. “Smaller fish click their teeth together,” he said.
The fish behavior expert also said that any fish sounds that an angler hears above the water is not the same as what would be heard under.
“It’s tough for people to hear fish noises (in the water),” he explained. “For schooling fish, like herring, sound is a close-range thing to keep the integrity of the school.”
With tongue planted firmly in cheek, Wilde assured animal rights activists that fish do not scream when hooked. “We put a hydrophone in a phone where we catch a lot of bass,” he said. “And that did not happen.”
One of the reasons that the learning curve regarding soniferous fish has improved in recent years is that researchers have modified their diving gear. For years, they were unaware of conversations because sounds of bubbles released by SCUBA gear masked them, as well as frightened the fish.
Now researchers use self-contained breathing systems so no gas bubbles are released.
“Increasingly scientists are discovering unusual mechanisms by which fish make and hear secret whispers, grunts, and thumps to attract mates and ward of the enemy,” said LiveScience.com.
“In just one bizarre instance, seahorses create clicks by tossing their heads. They snap the rear edge of their skulls against their star-shaped bony crests.”
Meanwhile, the swim bladder, also used to control buoyancy, is one of the most common instruments for fish sounds. A muscle attached to the swim bladder contracts and relaxes in rapid sequence, causing the organ to produce a low-pitched drumming sound.
Some species use stridulation, pushing teeth and/or bones together. And still others use body movements to make sounds by altering water flow.
Yes, fish have ears --- of a sort. Actually they possess ear bones known as “otoliths.” Also used to age fish, they vary in shape and size according to species, just as human ears vary from individual to individual.
Only fish otoliths can’t be seen eternally.
Sound travels through water as waves or vibrations, and, because a fish’s body is of similar density, the waves pass through it. But they cause the ear bones to vibrate.
Additionally, a fish can sense vibrations and movement with its lateral line, which is a sensory organ consisting of fluid-filled sacs with hairlike cells, open through a series of pores along the side. And the swim bladder works in a similar fashion, according to Robert Castenada, founder of Livingston Lures, which mimic distress sounds from shad.
“A fish has three ways to pick up sounds, but only one way to see and smell,” he added. “That’s why, in my opinion, sound plays the biggest role in bass locating prey.”
But because sound travels farther and 4.4 times faster in water than in air, a fish can struggle to hear through the “clutter” of outboard engines and recreational activity, according to Hydrowave, which makes a sound device designed to attract bass and other game fish by imitating the sound of baitfish and predatory fish feeding on them.
“This speed, combined with the poor visibility characteristics of water is the reason that a fish is so dependent on vibration and water displacement . . . for location of prey,” the company said.
“The source of sound clutter is always present. This forms the basis of how fish have developed keen senses that allow them to specifically identify clutter from prey and feeding activities of other fish.”
Four-time Classic winner Kevin VanDam said that the Hydrowave works in two ways. “It excites the fish because they hear the sound of other bass eating,” he explained. “And it excites the bait. It draws it up.”
On the other hand, Castenada’s topwaters, jerkbaits, wakebaits, and crankbaits replicate the distress sounds that shad make when they are assaulted by bass. For years, anglers have used rattling baits. But the lure designer said those just make noise, while his make “an actual biological noise.”