In our July-August issue, Judith Lewis reports on the plague of ocean noise that’s taking a toll on marine mammals throughout the world’s oceans.
Where does the ruckus come from? Industry: seismic air guns that petroleum outfits use to sound the depths for oil-rich pockets, acoustic deterrent devices fishing operations rely on to warn marine mammals away from their nets, and the sonar used by military and other vessels for underwater communication.
Michael Stocker, director of the Lagunitas, California-based advocacy group Ocean Conservation Research, explains that for a whale the sounds of technology may be like “somebody following you around all day running their fingernails down a blackboard.”
Take a listen to the industrial and natural sounds below to make your own comparisons.
The Ocean’s Industrial Racket
These two types of communications sonar are used to communicate underwater with remotely operated vessels, submarines, and other equipment.
M Sequence Communications Sonar
Arrays of airguns are used for seismic surveys, especially by petrol companies looking for oil. Blasts of compressed air create impulses that hit the ocean floor and are picked up again by hydrophones to give a reading of what’s beneath the ocean floor.
The Ocean’s Natural Noises
Here are sound samples from belugas and stenella blue dolphins. Ocean Conservation Research explains that these toothed whales’ sounds “pick up at the upper range of human sound perception and in some cases extend up to 10 times higher than our highest frequency perception. Toothed whales use their vocalizations for echo-location, or ‘bio-sonar’ as well as for high speed, short range communication to their kin.”
Special thanks to Micheal Stocker, director of Ocean Conservation Research for coordinating the use of these files and providing background on their significance.
Blue dolphin and beluga whale songs courtesy of Manon.org. The Audiograms in these sound examples were produced by Raven software, created by the Cornell Lab of Ornithology Bioacoustics Lab under the direction of Christopher Clark, Kurt Fristrup and Tim Krein.
