Diving behaviour of narwhals (Monodon monoceros) at two coastal localities in the Canadian High Arctic.

In August 1999 and 2000, four suction-cup-attached time-depth recorders were deployed and retrieved from narwhals (Monodon monoceros) in Tremblay Sound, Baffin Island, and Creswell Bay, Somerset Island, Nunavut, Canada. The narwhal (Monodon monoceros) is a High Arctic ice-associated cetacean that travels thousands of kilometres each year between shallow coastal summering grounds and deep offshore wintering grounds. Narwhals are among the deepest diving cetaceans and have been documented to reach depths of 1000-1500 m (Heide-Jørgensen and Dietz 1995. The number of dives per hour below 8 m ranged from 9 to 13, with an average of 10.9 dives/h (SD 1.2 dives/h) below 8 m. The deepest recorded sounding in Tremblay Sound is approximately 270 m (National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce and maximum depths for both individuals were 256-258 m. Therefore, it appeared that the whales were diving to the bottom of their habitat during the period when they were tracked.