Local News

Study: Noisy tests offshore possibly scaring fish away from reefs

Posted January 31
Updated February 1

— The sonic tests used to map the ocean floor in order to explore for oil and gas is scaring fish away from reefs, according to a first-of-its-kind study released by a University of North Carolina at Chapel Hill researcher.

Avery Paxton, a marine ecologist with UNC's Institute for Marine Sciences, has for two years been studying the effects of loud manmade noises on fish in the ocean.

"These noises, on the reef, they're repetitive," Paxton said. "The sound levels on the reef that were heard by these fishes were loud enough that, in laboratory experiments, fish did have physiological damage."

Survey ships blast sound waves through the water to the floor of the ocean and use the reverberation to map the ocean and determine likely spots to drill for oil and gas.

Paxton mounted cameras and microphones on reefs off the North Carolina coast. While fish are present in large numbers, a steady din similar to being in a crowded room can be heard. But during the period of seismic surveying, most fish leave the area rather than be subjected to the 230-decibel booms – nearly three times the measured level of normal reef sound.

Paxton called the study's results surprising.

"We weren't expecting the fish to respond in that way. We were really surprised that four out of five fish were no longer on the reef," she said.

Because divers are not allowed in the water and ships aren't allowed in the area during seismic surveys, batteries on the researchers' cameras and microphones had died by the time they returned, which Paxton said leaves many questions needing further study.

"We don't know how long this decrease of fish on the reef lasts," she said. "I want to know how long the fish stayed away from the reef. What happened to them? What caused them to leave the reef? Was it that the noise was too loud? Was it that they were feeling the noises differently than we do?"

She said the impact of the sonic testing could be felt across North Carolina.

"If the fish don't come back to the reef or if there is a longer-term effect of the fish leaving the reef temporarily, it has potential to cause harm to our coastal citizens and our economy and our culture," she said.

The study was funded by the Bureau of Ocean Energy Management and produced with partners from UNC, Duke University and the National Oceanic and Atmospheric Administration.

3 Comments

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  • Bob Herrmann Feb 1, 9:14 a.m.
    user avatar

    All activity foreign to any environment causes disruption.
    Wind farms, for example, kill hundreds of thousands of birds every year while in use, whether on or offshore.
    Offshore farms drive aquatic life away in the same way that those sonic tests do. The pile drivers used during construction are as loud as those tests, and building a farm means that the pile driving is a noise that is constant and lasts for years. Then there are the long term noise from the farms that has yet to be fully studied, but indications from studies done in Europe indicate that some species of both aquatic life and water foul are adversely affected, but others are not. Electromagnetic radiation from the cables are known to have effects.
    Bottom line is that any operation, either on land or sea, will have consequences. The trick is trying to determine if those consequences offset any positive gains.
    I get the feeling that this article is biased toward the anti-fossil fuel contingent

  • Dan Ratka Feb 1, 8:18 a.m.
    user avatar

    One more thing. The reason they don't want divers in the water is because the divers would be injured by the sound and they don't want boats in the area because they don't want people to witness all of the stunned fish floating around the mapping vessel. Have you ever heard of fishing with dynamite. Think about it.

  • Dan Ratka Feb 1, 7:57 a.m.
    user avatar

    Persons who are exposed to continuous sound over 85 decibels can suffer hearing loss. If you were exposed to 230 db sound you would leave the area pretty quickly with one heck of a ringing in your ears. Even with hearing protection you would be uncomfortable enough to get the heck out of there. Sound travels better in water than it does in the air. Bad news for the fish. Sound blasts are used to scare birds at airports around the country. What is the difference. Suprise, the fish don't have ear plugs. This is not the best mankind can do!