A study by a team of University of South Florida and Mote Marine Laboratory scientists has concluded that hearing loss may play a role in the stranding of whales and dolphins, according to a joint press release from the two institutions Friday.
In the study, published in the journal PLoS One, researchers found severe to profound hearing loss in 57 percent of the stranded bottlenose dolphins and 36 percent of the stranded rough-toothed dolphins.
The species rely on echolocation for orientation and feeding. Researchers believe that hearing loss could play a significant role in some strandings, said David Mann, a USF biological oceanographer and the paper’s lead author, according to the press releases.
Given the role hearing loss might play in their trauma, veterinary experts, scientists and resource managers might want to rethink the rehabilitation and release of dolphins, the study suggested.
A team of 16 scientists from the United States and the Caribbean examined 36 dolphins and toothed whales in Florida and at a number of aquariums and rehabilitation centers.
The animals had been found stranded or entangled in fishing gear between 2004 and 2009. They ranged from calves to adults.
The scientists found strong trends among the bottlenose and rough-toothed dolphins suffering from hearing loss, and the only short-finned pilot whale examined also had profound hearing loss.
No hearing impair- ments were detected in any of the seven Risso’s dolphins from three stranding events, or from two pygmy killer whales, one Atlantic spotted dolphin, one spinner dolphin, or a juvenile Gervais’ beaked whale that were part of the study group, the press release said.
“Cetacean hearing problems were hypothesized to be a cause of strandings even before the 1970s, when Mote became one of the first organizations studying why marine mammals strand, through necropsies and treatment of live-stranded cetaceans,” said Randall Wells, director of the Sarasota Dolphin Research Program.
“Finding that many stranded cetaceans do indeed have hearing problems is an important advancement in our understanding of these phenomena.”
