Post Date and Author: 
- by 

(November 24, 2010) – What role might hearing loss play in the “stranding” of 1,200-1,600 dolphins each year along America’s coastlines? This is the question being explored by New College of Florida psychologist Dr. Gordon Bauer and fellow researchers led by Drs. David Mann and Mandy Hill Cook from the College of Marine Sciences at the University of South Florida, Mote Marine Laboratory and Portland State University, as well as others from around the country.

The study was funded in part by the National Oceanographic and Atmospheric Administration (NOAA) and the Office of Naval Research (ONR). The team’s findings are published in the November 2010 issue of the science journal PLoS ONE.

While admitting that the cause of hearing loss in marine mammals can be difficult to pinpoint, researchers on the team in which Dr. Bauer participated found a significant correlation between dolphin strandings and hearing loss.

Fifty-seven percent of the stranded bottlenose dolphins and 36 percent of the stranded rough-toothed dolphins studied exhibited severe to profound hearing loss.  The only stranded short-fin pilot whale in the study also exhibited profound hearing loss.

The levels of hearing loss in the stranded dolphins stood in stark contrast to findings from capture and release studies of dolphins in Sarasota Bay that showed a general absence of hearing loss among the general population of the marine mammals living in the bay.

There are five main contributing factors to hearing loss in mammals, according to the team.  They are intense chronic noise, transient intense noise (e.g. explosions), age-related hearing loss (presbycusis), congenital hearing impairment and ototoxic drug treatment. While the team’s current research did not seek to determine which of these factors might have contributed to the hearing loss in the stranded dolphins, it left open the door for future investigation, including exploration into the role that underwater noise pollution might play in hearing loss among marine mammals.

Click here to view the research article “Hearing Loss in Stranded Odontocete Dolphins and Whales” appearing in this month’s issue of PLoS ONE.

For more information, contact the New College Office of Public Affairs at 941-487-4153 or email [email protected].