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Sunday, Nov 18, 2018
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Most beached dolphins have hearing loss, Mote study finds

SARASOTA - Dolphins are beautiful creatures, but mysterious, and perhaps no mystery is greater than why each year a small number of dolphins beach themselves, usually fatally. Now a Mote Marine scientist thinks he has found at least part of the answer: Deaf dolphins. Randy Wells, who helped author a study about dolphin strandings, said most dolphins that beach themselves have at least partial hearing loss. The answer isn't as surprising as it seems, Wells said.
"These animals live in an environment where they can't see very far, just because it's water and it's oftentimes murky. "So sound is a crucial player in their lives." So crucial, Wells says, that a dolphin with hearing problems will find it almost impossible to find food, to stay with other dolphins in their pod and to keep their sense of direction. Wells, David Mann with the University of South Florida and 14 other researchers studied numerous cases of dolphin strandings. To test their hearing, they used the same basic hearing tests doctors use on infants. The result? "A disproportionate number of the dolphins that come ashore are suffering from hearing loss," Wells said. The study's findings offer the first documentation of hearing loss in dolphins and whales. Wells said it's the first official confirmation of a problem suspected by marine mammal scientists for decades. He said the research impacts whether future stranded dolphins and whales can ever be released after rehabilitation because permanent hearing loss probably means the marine mammal cannot return to the wild. Wells cautioned hearing loss isn't the sole factor behind all strandings. "Injury, disease - these are all factors that enter into it, but we now have a better understanding of one thing that can bring them up on the beach."
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