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He is responsible for the decompression and death of one type of whale, according to the conclusions of a study that has analyzed the massive strandings of the Cuvier beak whale.
Scientists led by Spanish researchers from the Institute of Animal Health of the University of Las Palmas de Gran Canaria (Spain), have linked the massive strandings of whales, especially the Cuvier, with the use of medium frequency sonar in naval military exercises , so they opt for the prohibition of these devices as a mitigation measure.
The study, published this Wednesday by the scientific journal Proceedings B of the Royal Society, shows how massive strandings of bill whales increased markedly since the 1960s, after the development of this military-grade device , used to detect submarines .
New research and its analysis have found pathological findings coinciding with decompression sickness . The point of inflection was the necropsies performed on 10 specimens of the 14 whales stranded in 2002 in the Canary Islands, which showed disseminated microvascular hemorrhages associated with fatty and generalized emboli in the blood vessels and vital organs, all compatible with a similar disease to decompression.
The explanations they provide on how these marine mammals can develop gaseous emboli is that the sonar would cause the specimens to swim far from the sound source in shallower waters; that they interrupt their diving profile and there is nitrogen accumulation and the formation of bubbles; that physiological changes occur; and direct tissue damage from exposure to sound.
Also, what they suggest is that a single word could explain everything: stress. The study concludes that it is most likely that these animals have experienced a “flight or fight” response to escape sonar. And the more severe are the changes they experience in that ‘fight’, the greater possibility of taking the individuals with a higher level of individual risk to a non-reversible condition, leading to death .
First detected in the 1980s
In other cetaceans the cause of the typical massive strandings has not been determined, but it has been possible in the case of the atypical stranding of Cuvier whales. The association of this event with the naval exercises was identified for the first time in the Canary Islands at the end of the 1980s, but the connection with this device was more definitely established during a similar event in Greece in 1996 and another one in the Bahamas in the 2000
Thus, it has been proven conclusively that the 2004 prohibition of sonars in the Canary Islands successfully prevented new massive strandings of this species of cetacean in the region. However, these atypical groundings have continued in other parts of the planet, especially in the Mediterranean Sea , with individuals examined showing signs of decompression sickness, in areas where military exercises prohibited in the Canaries were carried out. . And this is the reason why they recommend that measures such as the one implemented in said Spanish archipelago be carried out.
Development of sonars
The active sonar of average naval frequency was developed in the decade of 1950 to detect submarines, using frequencies of 8 kilohercios or superiors. However, massive strandings, mainly Cuvier whales, did not occur until this instrument changed to lower frequency ranges of 4.5-5.5 kilohertz.
Until then, massive whaling of whales was extremely rare throughout the world and by the 1960s only 15 cases involving five species had been detected. But between the years 1960 and 2004, 121 events of this type were reported , all in the northern hemisphere and 61 involving Cuvier whales.