Loud Sonar Causes Deafness in Dolphins
Dolphins can be deafened by loud noises, which can lead to death.
A new study has found that loud sonar can cause deafness in dolphins.
The study found that loud, repeated blasts of sonar caused dolphins to temporarily lose their hearing for 20 to 40 minutes.
Published in the British journal Biology Letters on Wednesday, the findings could provide further evidence that human made noises can be attributed to dolphin and whale deaths.
The study, led by Aran Mooney Marine Biologist at the University of Hawaii, exposed an Atlantic bottlenose dolphin to progressively louder pings of mid-frequency sonar. The dolphin was born in captivity and was trained.
A suction cup was fitted to the dolphin’s head, with a sensor attached that monitored the animal’s brainwaves.
“What we found was if you play sound you can cause temporary hearing loss. The sounds have to be surprisingly loud and they have to be repeated over an extended period of time – two to three minutes.” Mooney said. “In that time you would expect them to swim away as fast as possible. They have to be within 40 metres of a ship, but when you have certain oceanographic conditions it’s hard for the animals to get out of the way.”
Many people believe that human made noises, also referred to as acoustic smog, has been the cause of whale and dolphin beachings around the world.
Mooney acknowledges that, given the study was undertaken in a lab with a captive-born dolphin, it does not provide proof that military sonar is to blame for mass strandings.
“We definitely showed that there are physiological and some behavioural effects [from repeated, loud sonar], but to extrapolate that into the wild, we don’t really know,” Mooney told AFP.
Tags: dolphins, marine life, sonar, whales
April 9th, 2009 at 3:54 pm
This type of news sickens me….when will our disregard for other inhabitants on this planet end. This piece of news is only reaffirming what many of us have felt/suspected for years.
April 11th, 2009 at 1:16 pm
Wow. I remember the Navy conducting tests on whales to see if sonar harmed them in any way, however, I can’t remember the results. But I can definitely see how prolonged exposure to these types of noises can damage a marine mammal’s hearing as well as navigational senses.