The high-frequency noise caused by passing ships pose a serious threat to killer whales and dolphins. A new study published in the journal PeerJ shows that the ships’ noise could be disturbing the marine animals’ communication and ability to find prey. Porpoises and dolphins that also operate at higher frequencies might be suffering the same problems.
Killer whales send out high-frequency clicks to locate prey
The new study conducted by researchers at Beam Reach Marine Science and Sustainability School in Seattle found that ships also generate high frequency noise that travels much farther. Killer whales locate their favorite prey salmon by sending out high-frequency clicks and listening for the echo. This process could be disrupted by the similar frequency noise from ships.
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The increasing ship traffic has raised the level of underwater sound pollution, threatening a wide range of endangered marine species. Dr. Scott Veirs, the lead author of the study, said reducing the speed of tankers and container ships even by one knot could reduce the noise levels and help save many endangered species.
To conduct the study, researchers installed listening devices in the Strait of Juan de Fuca and Puget Sound calibrated for a wide range of frequencies. Veirs said whales are wonderfully vocal, but their environment is filled with ship noise. Previously, scientists had assumed that the frequency of noise generated by shipping traffic was below the frequencies used by whales. But the new study debunks those assumptions.
Ships produce 173 underwater decibels of noise
Scientists recorded and compared noise from 41 types of ships making 2809 trips through the Haro Strait. All ships produced high-frequency noise. An important summertime whale habitat is just a few kilometers away from the busy shipping lanes where ships produce significant underwater noise pollution. The frequencies of the noise interfere with the marine animals’ foraging, communication, and echolocation.
Some ships are quieter than others. Ships produce an average noise of 173 underwater decibels. That is equivalent to 111 decibels through the air, or the sound of a loud rock concert.