Deafness in the deep
7th June, 2000
A new threat to whales, dolphins and other marine life exists in the worlds oceans, as the US Navys new sonar technology could have huge long-term effects on their whole way of life. Leigh Calvez reveals why the lords of the sea aren't singing any more.
Ever eager to protect itself against enemies, the US Navy has developed a new technology to help it detect opposition submarines. It's called Low Frequency Active (LFA) Sonar, and is capable of sending low frequency sound pulses - up to 240 decibels - into the water over hundreds of miles, bouncing an echo back to the listener, thus detecting an enemy submarine.
In the depths of the oceans, man-made sonar is nothing new, but this is the first time that it has been as loud and as powerful. Surely, then, it has been tested for its effects on the creatures of the sea that depend upon sound in the way that we depend on sight: the whales and dolphins?
Not sufficiently, say many scientists. Studies published in scientific literature over the past twenty years suggest that sounds from 110 to 120 decibels begin to cause disturbance to whales. Dr. Linda Weilgart, a Canadian biologist from Dalhousie University who has studied sperm whale communication for sixteen years, points to the long-term effects from the use of this technology as reason for concern. In The Christian Science Monitor, she states, 'to determine the health of a population (that is, whether it will survive), we need detailed,...
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