Diving behaviour of narwhals (Monodon monoceros) on their summer grounds

Three adult female narwhals from the population that summers in the sheltered waters of northern Baffin Island, Canada, were fitted with satellite-linked UHF radio packages. The units logged and transmitted diving and swim-speed data and revealed the location of the study animals for periods of up to 19 days. Most diving activity was in the top 40 m and bottom 40 m of the water column. Shallow dives were characterized by low rates of descent and ascent (<0.5 m∙s−1), short submersions, and frequent changes of vertical direction. Deep dives were normally to, or near to, the seabed in depths of up to 257 m, and involved both faster rates of vertical movement (1–2 m∙s−1) and longer periods underwater (up to 15.1 min). Midwater dives were intermediate in all respects. Deeper dives were of a characteristic "square" profile and provided an average of 7 min at the chosen depth, representing 57% of the time submerged. No dives were demonstrably longer than the estimated aerobic dive limit for this species. Activit...

[1]  Bernie J. McConnell,et al.  Foraging ecology of southern elephant seals in relation to the bathymetry and productivity of the Southern Ocean , 1992, Antarctic Science.

[2]  K. Finley,et al.  Summer diet of the narwhal (Monodon monoceros) in Pond Inlet, northern Baffin Island , 1982 .

[3]  W. Scoresby.  An account of the Arctic regions , 1820 .

[4]  Harry R. Burton,et al.  The Diving Behaviour of Adult Male and Female Southern Elephant Seals, Mirounga leonina (Pinnipedia : Phocidae) , 1991 .

[5]  T. G. Smith,et al.  Distribution and Abundance of Belugas, Delphinapterus leucas, and Narwhals, Monodon monoceros, in the Canadian High Arctic , 1985 .

[6]  K. Finley,et al.  Marine Mammals Inhabiting the Baffin Bay North Water in Winter , 1980 .

[7]  C. W. Turl.  Winter sightings of marine mammals in arctic pack ice , 1987 .

[8]  P. Richard.  Abundance and Distribution of Narwhals (Monodon monoceros) in Northern Hudson Bay , 1991 .

[9]  R. Dietz,et al.  Movements and swimming speed of narwhals, Monodon monoceros, equipped with satellite transmitters in Melville Bay, northwest Greenland , 1995 .

[10]  B. McConnell,et al.  Satellite tracking of grey seals (Halichoerus grypus) , 1992 .

[11]  L. Dueck.  The abundance of narwhal (Monodon monoceros L.) in Admiralty Inlet, Northwest Territories, Canada, and implications of behavior for survey estimates , 1989 .

[12]  Yasuhiko Naito,et al.  Prolonged, continuous, deep diving by northern elephant seals , 1989 .

[13]  S. Ridgway,et al.  Diving and blood oxygen in the white whale , 1984 .

[14]  A. R. Martin,et al.  Deep Diving in Wild, Free-Ranging Beluga Whales, Delphinapterus leucas , 1992 .

[15]  R. Dietz,et al.  Some characteristics of narwhal, Monodon monoceros, diving behaviour in Baffin Bay , 1995 .

[16]  Per Berggren,et al.  Diving behaviour of harbour porpoises, Phocoena phocoena , 1995 .

[17]  H. Fisher,et al.  Arterial retia related to supply of the central nervous system in two small toothed whales– narwhal (Monodon monoceros) an beluga (Delphinapterus leucas) , 1982, Journal of morphology.