Whale song at 'rock concert' levels 200 years ago
October 24 2012 Lewis Smith
The oceans were a much noisier place two centuries ago than they are today, according to an acoustics study.
Ships, sonar, oil platforms and other man-made contraptions make plenty of noise but by comparison they would have been outdone by the whales singing in the seas at “rock concert” levels in 1800.
However, so many whales were slaughtered by the whaling industry that numbers are now at a fraction of historical levels, as is the noise they make.
Michael Stocker and Tom Reuterdahl, of Ocean Conservation Research in California, used whale population estimates from 1800 to work out how much noise they would have made in the past.
Using modern measurements of how the sounds that modern-day whales make and combining them with population estimates they were able to determine historic noise levels in the seas and found it exceeds today’s background noise.
Mr Stocker, the director of Ocean Conservation Research, said: “In one example, 350,000 fin whales in the North Atlantic may have contributed 126 decibels – about as loud as a rock concert – to the ocean ambient sound level in the early 19th century."
Today there are thought to be fewer than 100,000 fin whales worldwide. Research into noises in the oceans is being carried out amid concerns that man-made sounds are having a detrimental impact on animal migrations and behaviour. Military sonar, in particular, has been linked with whale strandings.
But while the study shows that historic noise levels might have been much higher than they are today, the researchers pointed out that man-made sounds may well have different impacts on the marine environment.
"We can assume that animals have adapted to biological noise over the eons, which may not be the case with anthropogenic noise. Anthropogenic noise is often broader band and differently textured than natural noise, so the impacts are likely different as well. Investigating these differences and their impact on marine life is the topic of intense research," said Mr Stocker.
The findings are presented at the 164th meeting of the Acoustical Society of America (ASA) which is meeting in Kansas City, Missouri, in the US.
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