Thursday, April 19, 2012

Why Whales Beach Themselves

The late Dick Clark wrote in his last post in his blog: "We are constantly surrounded by sound. In a modern world, we are exposed to millions and millions of sounds, both pleasant and unpleasant, on a daily basis. Sometimes it seems enough to drive a person mad..."

Indeed. And in comparison to other species, we are not even particularly sensitive in terms of sound. We can tolerate sounds up to 130 decibels (dB) in loudness, although lower volumes will make us deaf sooner or later. 130 dB is called the threshold of pain. The decibel scale is logarithmic, which means that adding 10dB to the loudness indicates a TEN TIMES increase in the power of the sound. 140dB indicates a power level TEN TIMES louder than 130dB.

We know that marine animals rely a great deal on their hearing. We know that whales can communicate over tremendous distances by using sound.

Now consider an innocent-sounding little blurb published recently in the Washington Post:
Interior Secretary Ken Salazar announced a plan to allow oil and gas companies to conduct seismic mapping surveys of the ocean floor along the Atlantic coast, a significant step toward allowing offshore oil drilling.
Seismic mapping is a technique that employs such equipment as air guns, water guns, and "boomers" to create sound waves loud enough to vibrate the ocean floor. This means creating sound waves that measure 250 dB. 250! That is 1,000,000,000,000 times greater than the "threshold of pain"! (That's ONE TRILLION times the sound power.)

Illustration of seismic mapping from the EPA web site.

A seismic survey takes about two or three weeks and can span hundreds of miles of ocean. Imagine being caught in an onslaught like that. Your entire body is vibrating beyond belief. Your eyes and ears explode. The ocean has become a hell-like environment.

Beaching yourself is the only escape from the torture.

Even at a distance from the source of the sounds, it has been observed that it is much more difficult for the animals to find food. They may even abandon their traditional habitats.

The BP disaster in the Gulf of Mexico should have been our wake-up call to move away from oil. Instead, we're engaging in more destruction. Why? Because it's only animal life that we're torturing.


  1. Good post. One exception... whales do not perceive the loud booms as sound since the frequency is below their range of hearing. These booms represent rapid changes in pressure that induce barotrauma. Barotrauma is as deadly as deafness in whales since it prevents diving and feeding. Barotrauma also disables the ability of the whales to navigate.

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  2. Good article at I recommend it.