Scientists have long known that some vessels are afraid of whales and die in agony after exposure to the marine sonar, and now they know why: giant marine mammals suffer from decompression, just like divers.
The first blush, the explanation presented on Wednesday by 21 experts in the newspaper "Royal Society" Procedures B seems incredible.
Millions of years of evolution turned the whales into perfectly calibrated diving machines, which for hours move a mile below the surface, feeding for food in deep depths.
The pulse slows down, the blood flow is limited, oxygen is preserved.
So, how could the most basic diver of deep sea water come with bubbles of nitrogen that rubbed the veins, such as a diving boot that rises too fast on the surface?
A brief answer: the muffins – especially a kind known as Courier – really, really scared.
"In the presence of a sonar, they are emphasized and swim vibrantly from the sound source, changing their diving scheme," said author Jara Bernaldo de Quiros, a researcher at the Animal Health Institute at the University of Las Palmas de Gran Canaria, Spain, for AFP.
"The response to stress, in other words, replaces the diving response, which makes the animal accumulate nitrogen," she added. "It's like an adrenaline shot."
A kind of sonar particularly throws these whales out of balance.
Today in naval patrols and exercises, especially by the United States and its allies in NATO, it develops in the 1950s for the detection of submarines, an active medium frequency synchronizer (MFAS).
Beginning in 1960, ships began to release underwater signals in the range of about 5 kilohertz (kHz).
Then began the mass beaching of muffins, especially in the Mediterranean.
Between 1960 and 2004, 121 of these so-called "atypical" mass switches were held, with at least 40 closely connected time and place with maritime activities.
These were not individual threads of old or sick animals, nor mass filaments like that of last November in New Zealand, when more than 200 pilot whales gathered together.
Instead, several or more whipped whales will be washed on the shore within a day or two, and no more than a few tens of kilometers of distance.
The deadliest episode, in 2002, saw 14 captured in the 36-hour period of the Canary Islands during a naval exercise by NATO.
"Within a few hours after the deployment of the sonar, the animals began to appear on the beach," said Bernaldo de Quiros.
Outside, the whales did not show signs of illness or damage: they had normal body weight and had no skin lesions or infections.
Internally, it was another story. The nitrogen gas bubbles filled the veins, and their brain was devastated by haemorrhage.
The autopsy also revealed damage to other organs, as well as the spinal cord and central nervous system.
CANARIAN ISLAND MORATIOR
As with altitude, reactions in humans and probably in whales to nitrogenous bubbles in the blood vary in type and intensity.
The 2003 study in Nature on the possible link between sonar and whale deaths led Spain to prohibit such naval exercises around the Canary Islands in 2004.
"By then, the Canaries were the hotbed of such" atypical "fibers," said Bernardo de Quiros. "From the moratorium, nobody happened."
The authors have called for similar prohibitions to expand to other regions where it is known that the rhytic whales are gathering.
Cuvier's grows up to seven feet (23 feet) and spines mainly on deep-water squid and fish. Her upward direction gives an impression of a lasting smile.
The whale is designated as "vulnerable" to the IUCN red list of endangered species and is thought to have a global population of 5,000 to 7,000.
Other threats include ship strikes, ocean pollution and climate change displacement.