3/10/2018 7:27:00 AM The lake where you live Feeling the noise
Ted Rulseh Columnist
Back in my kid days my older brother claimed that when he threw stones into the river where I was fishing, he wasn't scaring the fish. Now based on the findings of scientists I can pretty well prove him wrong.
The water environment is filled with subtle sounds that fish are comfortable among, but they do recoil from sharp, loud noises they aren't used to hearing. Stones hitting the water qualify.
Fish can both hear sounds and feel vibrations from louder noises. They feel vibration in their lateral lines, a set of sensory receptors along their sides. They hear with ears, which are not obvious on the surface but certainly do exist.
Fishes' ears are inside the skull, just aft of the eyes. As in humans, the ears not only detect sound but also regulate balance - important because fish need to maintain equilibrium in three dimensions (yaw, pitch and roll).
Where sound is concerned, fish don't need ear flaps like the ones we have because water is such an exquisite medium for conveying sound waves. For example, sound travels almost five times as fast in water as in air.
While the human ear has three main components - outer, middle and inner - fish have only an inner ear. Each ear includes hard, calcified structures called otoliths containing thousands of hairlike sensory cells. Nerve fibers connect these cells to the brain, which interprets them and directs the fish to action.
In some fish, the ears are connected by way of bones from the spine to the swim bladder, an air-filled sac that helps the fish control buoyancy. These species have more acute hearing, can hear sounds at greater distances, and can detect sound in a wider range of frequencies than other fish.
Fishes' ears regulate help balance by way of three arch structures connected to a sac called the labyrinth. This in turn contains sensory patches, rich in hair cells.
So, fish are well equipped to detect sounds. They're not very sensitive to sounds from above the water's surface, since sound doesn't travel well from air to water. Exceptions to this rule would be loud, sharp, low-frequency noises like the slamming of a car door or trunk. Also, fish can hear you banging around in a boat or dropping objects on its floor - because those sounds are conducted directly into the water.
The effectiveness of the lateral lines and ears varies with distance. The lateral lines work only within a relatively short radius, while the ears still detect sounds from farther away. The lateral lines also detect mostly sounds toward the lower end of the frequency range.
As one might imagine, the sense of hearing becomes more important to the fish as the water becomes murkier or daylight fades to night. In bright, clear conditions, fish can rely more on sight to find and capture prey.
So, yes, throwing stones into the water will likely scare off the fish you're trying to catch. And those noise-making lures you see advertised? In the right conditions, they can and do work.
Ted Rulseh, who lives on Birch Lake in Harshaw, is the author of the "The Lake Where You Live," a blog where readers can learn about the lakes they love - the history, geology, biology, chemistry, physics, magic, charm. Visit lakewhereyoulive.blogspot.com. Ted may be reached at firstname.lastname@example.org.
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