Abstract:

A small population of about 500 beluga whales, Delphinapterus leucas, resides in the Saint Lawrence estuary, isolated from other populations of its species. This population has been extensively studied over the last 12 years in terms of its seasonal distribution, size, age, group structure, pathology, and group behavior. It is now considered to be threatened by human activities including elevated noise levels due to a wide range of anthropogenic sources including merchant shipping and whale watching activities. A whale recovery plan is in development that will include hearing conservation. Ambient noise measurements mwere made at the three major sites of habitation of these whales to gain an understanding of the daily fluctuations in noise levels and to establish a baseline characterization of the acoustic environment at each site. The noise levels were related statistically by site, time of day, and human activity and compared to beluga hearing sensitivity curves [W. Au, The Sonar of Dolphins (1993)] and indicate the probability that hearing damage will occur for animals occupying two of the three sites. Specifically, 200 Hz, 500 Hz, and 1 kHz and 40 kHz were scrutinized. [Work supported by World Wildlife Fund Canada, Humane Society Canada, and Parks Canada.]