Rare Beluga whales may be losing hearing (Released: 2/20/97)
by Renu Sehgal, Office of University Communications.
STORRS, Conn. -- The small, endangered population of Beluga whales in Canada's St. Lawrence Seaway use their voices to survive, but they may be losing their hearing because of abundant human noise, University of Connecticut researchers have found.
The major threat to the 500 remaining whales has been toxic chemicals that pollute the waters of the Saugenay and St. Lawrence rivers. But now disturbance from shipping and whale watching is of increasing concern to residents, vessel owners and captains in Quebec.
"The Beluga is perhaps the most vocal and acoustically diverse of all the small whales," said Peter M. Scheifele, marine mammal bioacoustics researcher for the National Undersea Research Center at the Marine Sciences & Technology Center at UConn's Avery Point campus in Groton.
"They rely on sound for their livelihood, vocalizing not only to communicate, but also to navigate, find food and mate. So varied are their sounds they are called 'sea canaries' by people who live around them," he said. "What they are hearing is the equivalent of a nearly constant 85 decibels over an eight-hour period, which is on the brink of temporary hearing damage by human ear standards. While the whales can move away from ships, they have no way to protect their ears and cannot escape."
According to federal standards, unprotected workers are not allowed to remain exposed to 85 decibels for more than eight hours, or 115 decibels for more than 15 minutes because temporary hearing damage may result, including ringing in the ears. When exposed to constant noise, the temporary damage becomes permanent.
Scheifele has been studying dolphin and beluga whale acoustics for 12 years while in the U.S. Navy and at the Mystic Aquarium. For two years, he has researched noise and sound production near the belugas' habitat. In 1994, he detected and measured extremely high noise levels in the St. Lawrence Beluga habitat area, becoming concerned that Beluga calls are being overshadowed by noise and that they could sustain hearing loss.
Scheifele is proposing a two-year study on the effect human sources of noise have on the small-toothed whales. One part of the proposal calls for developing hearing tests and audiograms using whales who live at aquariums such as the Mystic Aquarium.
"Preliminary data indicate that there is reason to be concerned about noise levels and pollution in at least one of the three sites they inhabit," Scheifele said. "This should indicate to the Canadian government and people that there is a good reason to pursue studying this if we are to co-exist with the whales and not cause them hearing problems."
Scientists from the St. Lawrence National Institute of Ecotoxicology and the Group for Research and Education of Marine Mammals have been monitoring the lives of the belugas. Results from their studies recently led the Canadian government to request the development of a whale recovery plan. The Beluga species living in the St. Lawrence has been decimated by problems, leaving only 500 of its kind. Another type of Beluga whale lives in the Arctic.
Scheifele joined Canadian scientists with his own team: Ivar Babb, director of the National Undersea Research Center; Denise A. Monte, an audiologist from the American School for the Deaf in West Hartford; and his wife, Lesa M. Scheifele, an exotic animal trainer experienced with Belugas.
Scheifele will present the results of his beluga studies at the Acoustical Society of America meeting in June at Penn State.
"The answer is not to enact laws from the hip that put everyone in turmoil," he said. "We know almost nothing about how noises affect the Belugas and what these whales actually hear. We need to use what we do know to study them and create protective and adaptive measures that everyone can live with. But we must act before the cry of the Belugas becomes the silence of an extinct population."