By Dr. Hal Schramm

Except for an occasional bluegill smacking at the surface or a shad flicking, fishing is a quiet game. Imagine what fishing would be if fish alerted you to their presence like some birds and mammals alert hunters. A bass spooks out of some shallow weeds and lets loose a cackle like a cock pheasant, or you shut off the engine to listen for the “cluck-cluck-cluck” of bass feeding in the back end. You’re working your way down a bank when a bass snorts at you from downwind. Anglers might be more successful. Or they might be more frustrated if the fish don’t bite.

Maybe fish do make sounds but we don’t hear them. To date, only about 700 out of the 25,000 different species of fish are known to make sounds, but the number is growing as sound-detection technology advances and efforts to detect sound-producing fishes expand.

Although many of the fish known to produce sounds are of little interest to anglers, fish in the trout and salmon, catfish, drum and snapper families are known to make noise. Here are a couple examples.

Courtship-associated calls of red drum have been detected by hydrophone (underwater sound detection devices) towed in the Gulf of Mexico near Aransas Pass, Texas. Drumming is most intense in early evening hours. Only the males call, presumably to attract females, and drumming only occurs during the spawning season. This acoustic assessment suggests that red drum spawning is widespread along the coast rather than concentrated at inlets as previously thought.
As you might expect, the Hudson River in New York is a noisy place, but University of Massachusetts researchers found that some of the noise was fish talk. Ninety-five miles upriver from Manhattan, the researchers recorded eight different sounds that were thought to be from fish. Brown bullhead and channel catfish produced two of those sounds. No sounds were recorded from largemouth bass, smallmouth bass, or several sunfish when they were captured or held in tanks. Presumably, the researchers checked a wide range of frequencies.

It’s too early to tell if other popular sportfish may be clicking, clucking, grinding, or grunting, though. To hear a fish, you have to be dialed in to the right frequency, and obviously that frequency is not within the range of frequencies that our unaided ears detect.

Sound As Communication
Many of our popular game fish are sight-feeders, both for the capture of real food and the junk food we cast at them all day long. But, sight feeders would spend a lot of their life hungry if they relied entirely on vision to find food. Water clarity changes seasonally with algae blooms, heavy rain or heavy wave action. In some lakes and rivers, it is always turbid.

Biologists have learned that the lateral line system, which detects water movement and pressure waves in water, plays a key role in feeding. The lateral line system probably serves as a good back-up for finding food in turbid water, and anglers have learned to exploit this food-detecting sensory system by fishing lures that displace a lot of water when water clarity plummets.

Sound has gotten little attention as a sense for detecting food. This seems odd, because sound travels quickly in water—six times faster than in air. Furthermore, whereas pressure waves detected by the lateral line system are effective only at close range, sound travels a long way, even in turbid water. In other words, hearing, like vision, is a good sensory system for real-time detection in a fish’s environment. But unlike vision, detecting objects by sound is not subject to wide variations in water clarity.

Useful Sounds
As noted for red drum, signaling reproductive readiness and attracting like-minded mates has obvious advantages. Or, sound may be used to aggregate fish independent of any reproductive agenda. On the flip side, sounds may serve to disperse fish, just as a dog growls to displace another from his food bowl or a bone. Or, sounds may alert a prey fish to the presence of predators, much like a squirrel “chirrs” to alert others to danger.

But a more routine use of sound would be detecting prey. Many organisms make sounds. I’ve never heard crayfish clicking their pincers, but I’ve heard a lot of claims that they do. Nevertheless, I fish glass beads on my Carolina rig and assume someone with better hearing than mine knows the sounds crayfish make. Jaws snapping, joints clicking when fish move, vibrations of the swim bladder wall, or the sound of something skittering across the bottom are all possible sounds that a predator uses to detect prey.
Experienced anglers know that retrieve speeds can make a difference between a poor catch and a heavy bag. Is it sight? Is it pressure waves? Or is it sound? Almost every lure, not just those with rattles, makes some sound—hooks scratching against the plug body, worm weights clicking beads or hooks, a clevis squeaking on the wire arm of a spinnerbait. There are days when you want to throw the original Xr50 with multiple rattles, and there are days when a One-Knocker Xrk50 with its single tungsten ball will produce more strikes.

Bass anglers are already using sound to boost catches with the HydroWave unit, which transmits sounds into the water. These sounds are designed to mimic the noise of feeding and distressed baitfish. It may work; I haven’t seen the data. But could your next bass boat come equipped with a sound detection system that “hears” your favorite game fish or their prey? Far out? Maybe, but that’s what people thought when Darrell Lowrance stuffed a decade of World War II naval sonar technology into a green box and took it fishing.

One thing’s for sure, the water’s a noisy place. I spend a lot of my time assessing movement and habitat use of endangered pallid sturgeon in the Mississippi River using sonic telemetry. We capture sturgeon on trotlines and surgically implant sound-emitting (sonic) tags into them. The tags are about the size of your index finger.

Directional hydrophones in the water detect the ultrasonic sound bursts and pass the information to a receiver that decodes and amplifies the sound. Despite the suspended sand and noise from the swift current and occasional tow boats, we can easily detect tagged fish from more than a half mile away at depths of more than 50 feet.

It’s very possible that bass do make noise and we haven’t identified it yet. When we do, a whole new world of detection and attraction possibilities will emerge.