PARIS, Jan. 30 – Scientists have long known that some beaked whales slap and die in agony after exposure to the nautical sonar, and now they know why: Giant marine mammals suffer from decompression sickness as well as divers.
21 experts from the Royal Society magazine today explain the first blush Proceedings B seems unlikely.
Millions of years of evolution have transformed whales into perfectly calibrated diving machines that plunge miles below the surface for hours and search for food at ink depths.
The heart slows down, blood flow is reduced, oxygen is retained.
So how could the ocean's deepest diver reach the bubbles of nitrogen, the veins of the vein, as a diver who came to the surface too quickly?
Short answer: Beaked whales – especially one known as Cuvier's – get really, really afraid.
"In the presence of the sonar, they are highlighted and swim strongly from the sound source, changing their patterns of diving," says Yara Bernaldo de Quiros, a researcher at the Department of Animal Health at the University of Las Palmas de Gran Canaria, Spain.
"Stress reaction, in other words, prevents a response to diving that accumulates nitrogen in the animals," she added. "It's like an adrenaline shot."
One type of sonar, in particular, throws these whales out of balance.
Developed in the 1950s to detect submarines, Medium Frequency Active Sonar (MFAS) is now used in naval patrols and exercises, particularly the United States and its NATO allies.
Beginning in 1960, vessels began to issue underwater signals in the range of about 5 kilohertz (kHz).
At that time mass whaling of whale whales began, especially in the Mediterranean Sea.
Between 1960 and 2004, 121 so-called "atypical" massacres took place, of which at least 40 were closely linked in time and on site with maritime activities.
It was not an individual herd of old or sick animals, nor was it a mass mess, as in November last year in New Zealand, where more than 200 pilot whales together.
Rather, a handful of whales or more whales would be washed off shore within one or two days and no more than a few tens of kilometers apart.
The most deadly episode, in 2002, saw 14 during a 30-hour period in the Canary Islands during the NATO naval exercise.
"Within a few hours after sonar, animals began to appear on the beach," said Bernaldo de Quiros.
Due to external effects on whales, there were no signs of disease or damage: they had normal body weight and did not have skin lesions or infections.
Internally, it was another story. Nitrogen bubbles filled the veins and their brains were devastated by bleeding.
Autopsy also revealed damage to other organs, as well as spinal cord and central nervous system.
Canary island moratorium
As with altitude sickness, the reaction – in humans and probably in whales – in nitrogen bubbles in blood differs in type and intensity.
Study of 2003 v Nature about the possible connection between sonar and whale death, Spain in 2004 banned such naval exercises around the Canary Islands.
"Until then, the Canary Islands have been hotspots for this kind of" atypical "bond," said Bernaldo de Quiros. "There has been no moratorium since the moratorium."
The authors demand that similar bans be extended to other areas where endangered whales are collected.
Cuvier's tree reaches up to seven meters and breathes mainly on deep octopuses and fish. His upturned mouth creates the impression of a steady smile.
The whale is marked as "vulnerable" on the IUCN red list of endangered species and is expected to have a total population of 5000 to 7000.
Other threats include ship collisions, ocean pollution and biotope shifts caused by climate change. – AFP