Naval sonar essentially “scares whales to death” researchers discover
Since the 1960s, scientists have noted a link between the use of naval sonar and whales seemingly killing themselves, en masse, by stranding themselves on beaches.
A new study reveals the horrifying reason why.
“In short, the sound pulses appear to scare the whales to death, acting like a shot of adrenaline might in a human,” Science Alert reports.
The sound emitted by sonar is literally unbearable to marine mammals, causing them to swim hundreds of miles, dive deep into the abyss or even beach themselves to escape it.
When they dive too deep, too fast, nitrogen bubbles form in their blood resembling what divers would call decompression sickness or “the bends.”
The nitrogen can cause hemorrhaging and damage to whales vital organs.
The big question researchers had was how an animal that lives in the ocean and is adapted to perform deep water dives for hours at a time can get decompression sickness?
The answer, they found, was that whales typically descend gradually, lowering their heart rate to reduce oxygen use and prevent nitrogen build-up. But the sonar triggers a “fight or flight” response that causes them dart straight down.
“The stress response, in other words, overrides the diving response … It’s like an adrenaline shot,” lead author Yara Bernaldo de Quiros told AFP.
Beaked whales regularly dive deeper than a kilometer for around an hour at a time, but when exposed to sonar they may dive nearly three kilometers, and stay there for over two hours.
Sonar was developed in the 1950s to detect submarines. Mass strandings of beaked whales were essentially unheard of before then, The Independent reports.
But between 1960 and 2004 there were more than 100 mass strandings (beachings) reported and the number of species affected by the pulses increased.
Strandings in 1985, 1988, 1989, 1991 and 2002 coincided with naval sonar drills.
Some suspect military sonar exercises were behind the mass stranding of 145 pilot whales in New Zealand beach just last November and of more than 80 beaked whales in Ireland last summer.
In 2008, the British Ministry of Defense admitted the Royal Navy had been conducting operations close to the Cornish coast where 26 dolphins had died, after previously denying having any vessels in the area.
The researchers behind the new report want to see the use of sonar technology banned in areas where whales are known to live.
Such a ban has been in place in the Canary Islands since 2004.
“Up until then, the Canaries were a hotspot for this kind of atypical stranding,” Quiros said “Since the moratorium, none have occurred.”
The research was published in the Royal Society Journal Proceedings B.