– Navy Sonar
Hearing crucial in animals’ ability to feed, navigate
Rescue workers helped a dolphin on Lieutenant Island in Wellfleet, Mass., in March, when two groups of white-sided dolphins wounded up being stranded on Cape Cod. (Steve Heaslip/Cape Cod Times via Associated Press) By
WASHINGTON — New research into the cause of dolphin “strandings’’ — incidents in which weakened or dead dolphins are found near shore — has shown that in some species, many stranded creatures share the same problem.
They are nearly deaf, in a world where hearing can be as valuable as sight.
That understanding — gained from a study of dolphins’ brain activity — could help explain why such intelligent animals do something so seemingly dumb. Unable to use sound to find food or family members, dolphins can wind up weak and disoriented.
Researchers are unsure what is causing the hearing loss: It might be old age, birth defects, or a cacophony of man-made noise in the ocean, including Navy sonar, which has been associated with some marine mammal strandings in recent years.
The news, researchers say, is a warning for those who rescue and release injured dolphins: In some cases, the animals might be going back to a world they can’t hear.
“Rehab is pretty time-consuming and pretty expensive,’’ said David Mann, a professor at the University of South Florida and the study’s lead author. If the dolphin can’t hear, he said, “there’s almost no point in rehabbing it and releasing it.’’
Read moreStudy of Stranded Dolphins Shows Many to Be Near-Deaf (Thanks to Navy Sonar)