When the International Whaling Commission meets this week to discuss the future of whale hunting, aquatic noise pollution will be low on the agenda, if it's discussed at all. But noise from humanity's ships may pose as great a threat to the magnificent creatures as any hunting fleet's harpoons.
Whales evolved in an environment where visibility is limited but sound practically unimpeded. They rely on hearing to find food, navigate, and communicate, calling to each other with elaborate vocalizations that can be heard for hundreds of miles, even, in the case of species like the blue whale's low sonic frequencies, across an entire ocean. Hearing is as important to whales as sight is to humans, if not more.
In the last decade, scientists have realized that noise generated by ships often drowns the natural sounds of the sea. Some types of sonar, especially those used by military vessels, can be heard for hundreds of miles. Together with engine noise, these produce an aquatic roar heard across Earth's oceans, often at levels that humans associate with airports and rock concerts.
To get a first-person sense of what it's like to be a whale, plug some headphones into your computer, close your eyes, and listen to this humpback whale song. It was recorded in a noise pollution-free environment. Then listen to this song, recorded in the waters off New York Harbor.
The effects of oceanic noise pollution are still being quantified. Awareness of the phenomenon is relatively new, and studying whale behavior is difficult. But loud noises have been linked to mass beachings and the departure of some species from traditional habitats. That may be just the beginning, especially when it comes to the effects of noise on whale communication and culture.
"We know very little about the effects of noise pollution, though the more we learn, the scarier it is," said Hal Whitehead, a Dalhousie University biologist and one of the world's foremost experts in whale vocalization. "And we know little about whale talk, though the more we learn, the more interesting it is."
See Also:
- Unique Killer-Whale Pod Doomed by Exxon Valdez
- Supreme Court: National Security Trumps Whales, Environmental Law
- Hydrophones Help Scientists Pinpoint, Protect Right Whales
Image: NOAA
Audio: Natural Resources Defense Council
Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter.
