Boston Section

On May 9th, the Boston Section enjoyed a free-wheeling and far-ranging presentation by Dr. Peter Scheifele of Norwich, Connecticut. Dr. Scheifele is the Director of Bioacoustic Research at the University of Connecticut's National Undersea Research Center. His talk began with a biographical slant as he explained how his background as a naval officer, diver, animal trainer (especially of marine mammals), and holder of degrees in oceanography and marine bioacoustics led to the investigations of whale hearing and marine "noise pollution."

Although noise and "noise pollution" for humans have been hot topics for many years, a debate on their effects on animals is now beginning to rage. Impact is being questioned not only in the natural environment but in the maintenance and development of captive environments as well. What does a whale actually hear? How do we know? What are the best ways to record oceanic sounds?

Currently 90 percent of Dr. Scheifele's work is done at a research station located in Tadoussac, Quebec on an estuary of the Saint Lawrence River. Here a community of Beluga whales has lived for many years, but the water is tremendously polluted (chemically, not just with noise) and the pod is down to only 700 individuals. The popularity of "whale watching" means that sometimes a single whale might be surrounded by 25 vessels at a time. The noise of these boats plus the merchant-marine traffic and local ferries in a river only 2 kilometers wide by 900 meters deep is having a great impact on these creatures who rely on sound for their livelihoods.

The Canadian National Marine Fisheries Commission has been tasked with "setting a number" to limit noise pollution in the whales' environment, and has turned to Dr. Scheifele for counsel. Currently there is no established limit, although 180 dB referenced to one micropascal is used by most marine bioacousticians.

Marine mammals in the wild are certainly not the most cooperative of hearing-research subjects. Much of what we know has been learned from animals in captivity, and in the open ocean we have no way of distinguishing audiological behaviors from other behaviors. Dr. Scheifele presented hearing-threshold curves for various whales and dolphins which exhibit peak sensitivies in the 40 to 70 kilohertz (!) range.

In addition to such amazing high-frequency audiological response (which is important for echo-location), whales are known to communicate with one another over incredible distances at frequencies we consider infrasonic (e.g., 5 hertz).

In his presentation to the Section, he played various hydrophone recordings of vessel noises and whale sounds. Unfortunately, man-made propeller noises are now a significant and offensive component of the whales' environment.

The meeting attendees also received a tutorial on marine-mammal anatomy. The aquatic ear is not like the human ear. The ear is not part of the skull, and the otologic bones are not connected to the tympanic membrane.

At the conclusion of the evening, Dr. Scheifele did a bit of recruiting for volunteers on this summer's voyages of whale-listening on the University of Connecticut's research vessel. He can be reached by electronic mail at acousticp2@juno.com or scheifel@uconnvm.uconn.edu.

-- Bob Wey