Paradoxical escape responses by narwhals (Monodon monoceros)

Research output: Contribution to journalJournal articleResearchpeer-review

Terrie M. Williams, Susanna B. Blackwell, Beau Richter, Mikkel Holger Strander Sinding, Mads Peter Heide-Jørgensen

Until recent declines in Arctic sea ice levels, narwhals (Monodon monoceros) have lived in relative isolation from human perturbation and sustained predation pressures. The resulting naïvety has made this cryptic, deep-diving cetacean highly susceptible to disturbance, although quantifiable effects have been lacking. We deployed a submersible, animal-borne electrocardiograph-accelerometer-depth recorder to monitor physiological and behavioral responses of East Greenland narwhals after release from net entanglement and stranding. Escaping narwhals displayed a paradoxical cardiovascular down-regulation (extreme bradycardia with heart rate ≤4 beats per minute) superimposed on exercise up-regulation (stroke frequency >25 strokes per minute and energetic costs three to six times the resting rate of energy expenditure) that rapidly depleted onboard oxygen stores. We attribute this unusual reaction to opposing cardiovascular signals—from diving, exercise, and neurocognitive fear responses—that challenge physiological homeostasis.

Original languageEnglish
Issue number6368
Pages (from-to)1328-1331
Number of pages4
Publication statusPublished - 8 Dec 2017

ID: 188266507