Beached Dolphins Are Often Deaf
In a fascinating study published on November 3 in the journal PLoS One, researchers looking into the cause of dolphin strandings found that in some species, many of these stranded creatures are nearly deaf.
That finding, which scientists gained from a study of the brain activity of the dolphins, could explain why such intelligent animals do something that appears pretty stupid: land themselves on a beach. Unable to use sound to find food or family members, these dolphins are often weak and disorientated.
Around 1,500 Whales And Dolphins Stranded Every Year
Every year, 1,200 to 1,600 whales and dolphins are found stranded off the U.S. coast, according to the National Oceanic and Atmospheric Administration. Most are dead and of the rest, many are euthanized on the scene or die later.
But how did they become deaf? These same researchers are unsure of that answer, but suggest that it might be old age, birth defects, or perhaps Navy sonar, which has been associated with several marine mammal strandings recently. (Click here for a report on the recent beaching of 33 pilot whales off County Donegal, Northern Ireland.)
Is Too Much Noise Making Them Deaf?
Other researchers have also identified another issue, connected to this one: too much noise in general in the ocean. Dolphins evolved when the only source of loud sounds underwater would have been thunderstorms, or occasionally volcanic eruptions.
Nowadays, however, there are the sounds of powerboats and huge oceangoing ships, in addition to oil and gas explorations that use loud noises to conduct seismic tests of the seabed.
Check Out The Dolphins’ Hearing!
Whatever the reason for their deafness, David Mann, the study’s leading author, who is a professor at the University of South Florida, hopes that his research will encourage organizations that rescue stranded dolphins to give the animals hearing tests. If the animals are found to have serious hearing damage, he said, he suggests that they might be kept at aquariums or other protected locations.
“If the dolphin can’t hear, Mann stated, “there’s almost no point in rehabbing and releasing it” because it probably won’t survive very long.
Why So Many Deaf Dolphins?
It seems that more effort should go into examining the causes of this deafness. Could it be that humans are once again upsetting the natural balance of the earth?
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