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

• Published in: Canadian Journal of Zoology
• Main Authors: Laidre, Kristin L, Heide-Jørgensen, Mads Peter, Dietz, Rune
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2002
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Arctic; Nunavut; Baffin Island; Canada; Somerset Island; Tremblay; Tremblay Sound; Baffin; Creswell Bay; Monodon monoceros; narwhal*
• Online Access: http://dx.doi.org/10.1139/z02-041; http://www.nrcresearchpress.com/doi/pdf/10.1139/z02-041

In August 1999 and 2000, four suction-cup-attached time–depth recorders (TDRs) were deployed and retrieved from narwhals (Monodon monoceros) in Tremblay Sound, Baffin Island, and Creswell Bay, Somerset Island, Nunavut, Canada. The TDRs remained on the whales for between 12 and 33 h and collected 64.5 h of dive data. Mean dive depths ranged from 20.8 m (SD = 14.8 m) to 50.8 m (SD = 43.8 m) and mean dive durations ranged from 3.4 min (SD = 1.6 min) to 4.9 min (SD = 4.5 min). There appeared to be individual differences in dive parameters both within a region and between regions. Three of the whales made short, shallow dives, while another whale made dives twice as deep and twice as long. One whale had maximum dive durations (>20 min) that exceeded predicted aerobic dive limits for narwhals. There was a strong relationship between maximum dive depth and duration for all whales (p < 0.0001). Narwhals spent between 30.3 and 52.9% of their time at depths <5 m and the range of correction factors for availability bias was 1.9–3.3. Satellite-linked TDRs were simultaneously deployed on the whales at both localities. Dive data collected using the two methods were compared and good agreement between the methods was obtained.