Mid-frequency sonar signals linked to new pathologic entity in cetaceans.
An ongoing battle has been fought between environmental NGOs , mainly NRDC , and the US Navy for more than a decade.
The first rumours re the harmful impact of LFA ( Low –frequency Active) sonar on marine mammals, began already in 1994 , when NRDC investigated sound experiments off California coast. Even 300 miles from the source , these sonic waves have an intensity of 140 decibels , and some mid –frequency sonar systems can put over 235 decibels , as loud as a Saturn V rocket at launch.
The use of deadly sonar in the world’s oceans is spreading. The US Navy states ,the sonar is needed to detect hostile diesel –electric submarines from China, Iran and North Korea and other potential hostile countries.
In late January 2008, a dead Northern Right Whale Dolphin washed ashore off California , and this death was linked to ongoing naval exercises.
“ The lesions that we have seen to date are consistent to what has been found in the Canary Islands and the Bahamas”, said lead veterinarian , Rowles , with the National Oceanic and Athmospheric Administration.
“Scientists in the journal Nature theorized that these deep-diving whales might have panicked and bolted to the surface, causing decompression sickness, similar to the “bends” or air embolisms that can affect human divers. The problem arises when gas bubbles, compressed under the pressure of depth, expand rapidly and tear delicate tissues”
Excerpt from Nature : “ Macroscopically, whales had severe , diffuse congestions and hemorrhage , especially around the acoustic jaw fat , ears , brain , and kidneys . “
Severely injured whales stranded and died due to cardiovascular collapse.
Another useful link :
LA Times: Dolphin dies near sonar site