Just like people, loud noises stress out fish, according to Carol Johnston, professor in the School of Fisheries, Aquaculture and Aquatic Sciences.
According to The New Yorker, the French scientist Étienne Lombard studied the effects of noise on human hearing in the early 1900s.
His findings, called the Lombard effect, suggest when noise is increased, human speech volume increases.
Since then, those findings have been extended.
Johnston said she specializes in researching the behavioral ecology and conservation of fish.
Johnston said she has studied the Lombard effect and how sound affects fish for 20 years, looking at how increased volume affects stress hormones in fish and believes traffic noise caused by humans results in higher stress levels in fish.
Johnston said loud noises alter the fishes’ hearing in a negative way.
“It’s like when you go to a rock concert,” Johnston said.
Johnston said anthropogenic, or human-generated, noise is a stressor for fish.
Fish that live near bridges are constantly stressed out, Johnston said, because they are always hearing the noise from passing cars on the roads.
Zhanjiang Liu, Associate Vice President for Research and Associate Provost of the School of Fisheries, Aquaculture and Aquatic Sciences, said the research Johnston is doing and the discoveries she has made are beneficial to everyone.
“Studying ecology is important to study so we can detect language and problems,” Liu said.
To do the research, Johnston used underwater microphones and a cortisol assay to measure hormone levels.
One experiment to test the effects of volume was conducted by Jenna Crovo, graduate student in fisheries allied aquacultures.
Crovo said she took recordings of traffic noise and looped it in the experiment. She played this sound for a group of blacktail shiners and measured the cortisol hormone content in them.
The fish hormones passed from the gills into the water, according to Crovo. She said she measured the cortisol in the water using the enzyme immunoassay, a biochemical test to measure the concentration of a substance.
Crovo discovered the hormone levels in the fish had increased.
Next, she played the loop for two hours. She said the fish began to lose their hearing and could not hear other specific sounds they could before.
This was tested by first playing the traffic noise. After listening to the traffic noise, she had to increase the volume so the fish could hear it.
The experiment took place last summer and lasted several months.
The experiment tested the effects after only two hours. Crovo said she was not sure if the pattern would continue after that.
“We want to see what happens from there,” Crovo said.
Liu said the research could potentially help the researchers manage the species of fish and how they react to noise.
When it comes to how fish respond to anthropogenic noise, Liu said, the more they know, the better.
According to Liu, future studies would come closer to fixing the negative impacts humans are having on fishes’ hearing.
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