Blue whales have gone from viola to baritones. The American magazine "The Atlantic" reveals Wednesday the results of a study conducted by researchers on the singing of the world's largest marine animals. Scientists note that over the past ten years, the tonality of the sounds that cetaceans use to communicate with each other has increased from 28 Hertz in 2002 to 25 Hertz in 2017. Their tone would therefore be more serious today.
>> Listen in the video above the songs recorded in 2002 and 2017
How to explain this phenomenon ? The studies remove the trail of marine noise pollution - ship traffic, military maneuvers, exploitation of oil deposits ... These sounds, generated by human activity, have been identified as the source of disorientation and stranding whales .
The number of mammals has risen to 25,000 today
The most likely explanation would be in fact that of redensification of the species. From a few hundred in the 1970s, mammals increased to 25,000 today. At the origin of this repopulation: the measures of protection of the species introduced from 1966 and the prohibition of hunting, set up in 1986.
Heard on europe1:
The whales are more numerous, closer to each other, so they do not need to scream anymore
The animal would no longer need to raise the tone to be heard. "The whales are more numerous, closer to each other, so they no longer need to shout," says Olivier Adam, professor of bioacoustics at the Sorbonne.
Another explanation: the ocean becomes more and more acidic with the emission of carbon dioxide in the atmosphere, the sound waves circulate more quickly in the water. Whales would no longer need to increase the volume to communicate.