It’s a well-known fact that noises carry a lot further underwater than in the air, but recently marine biologists noticed that underwater noises might disturb whales even if they are 120 miles (190 kilometers) away.
The pulsing sounds made by the technology that’s used to monitor fish stocks have been affecting how whales communicate, even at great distances. Marine biologists noticed that humpback whales sang less in the fall of 2006 when a low-frequency signal showed up in their recordings. This recording was traced to some acoustic sensing equipment that was used in part of a scientific study off the coast of Maine, which was 120 miles away from where the marine biologists were monitoring whale songs.
There were more frequent whale songs during the same time in 2008 and 2009, when this equipment wasn’t being used. The implication is that the technology and the low-level sounds made the whales react adversely and silenced their songs.
Denise Risch, author of the research published on January 11th in PLoS One, states that this is fascinating that there was a behavioral response over such a large distance. Previous research had indicated that nearby underwater sounds from ships, airguns, and explosions as well as sonar might cause hearing damage and changes in the patterns of feeding, mating, and communications among marine mammals, but this was the first time that whales were reported to react to man-made sounds from so far away.
Whales are social creatures, and some humpbacks sing for weeks at a time. In mating grounds, males sing to attract females and to show off to other males yet scientists don’t know why they sing in feeding grounds. The change was pretty dramatic and was a cause for concern.
Reference: “Changes in Humpback Whale Song Occurrence in Response to an Acoustic Source 200 km Away” by Denise Risch, Peter J. Corkeron, William T. Ellison and Sofie M. Van Parijs, 11 January 2012, PLoS One.