W. Ellison, Marine Acoustics , Inc.; L. T. Hatch and D. Wiley, NOAA SBNMS; S. M. Van Parijs, NOAA NEFSC
Noise drives many species of whales, dolphins, and other marine animals to change their behavior markedly—their calling, foraging, and migration patterns—even when it’s not enough to drive them onto a beach. Cod and haddock in the Barents Sea have been found to flee the area when air guns start firing, drastically reducing fish catches for days. Large baleen whales are of special concern. They communicate over vast distances in the same frequencies, around the lowest C on a piano, that ship propellers and engines generate. On most days, says Christopher W. Clark, director of the bioacoustics research program at Cornell University, the area over which whales in coastal waters can hear one another shrinks to only 10 to 20 percent of its natural extent.
Clark studies endangered northern right whales, whose habitat includes busy shipping lanes for the port of Boston. In 2007 he and his colleagues deployed a network of seafloor recorders and automated listening buoys in Massachusetts Bay. From three years of continuous recordings, they then compiled a complete underwater “noise budget.” Color animations of the data show the calls of right whales getting all but obliterated as ships pass. “The whales’ social network is constantly being ripped and reformed,” Clark says. Unable to communicate, individual whales have trouble finding each other and spend more time on their own.
The ten listening buoys now bobbing in Massachusetts Bay could actually help the animals. The researchers are sharing their real-time data on whale locations, transmitted from the buoys via satellite, with tanker captains, who can then slow down their ships or alter course to avoid whales. It’s a small note of hope in the din. “Science can only help in so many ways,” Clark says. “Then we have to decide whether the animals are important to us.” —Leslie Allen