Abstract

Little is known about physiologic parameters of free-ranging walruses, yet basic physiologic data such as resting heart and respiratory rate are essential for meaningful monitoring of anesthesia, and may contribute to estimation of energy consumption/metabolic rate. Observations were made on 10 free-ranging adult male walruses (Odobenus r. rosmarus) at Young Sound in Northeast Greenland (74°18′N; 20°15′W) in August 2004. Animals that had been out of the water for at least 1 hr were examined. A battery-operated electrocardiograph (Cardiovit AT-4 vet, Schiller AG, CH-6341, Switzerland) was equipped with custom made 10 m cords for bipolar recording. These cords ended in an insulated metal luer-lock connector for easy attachment of aluminium 18-gauge, 1.5″ hypodermic needles. Each subject animal was slowly approached and the two electrodes were simultaneously applied with the aid of two light-weight metal rods with a distal “cup” using a gentle, stabbing motion. The electrodes were placed in the dorsal midline approximately 100 cm apart. The electrocardiogram was recorded for 3 min, and the heart rate was subsequently calculated as the mean for this period. Respiratory rate was determined visually, by observing the nostrils and respiratory movements of the animal in question. Mean heart rate ±SD was 36±3.7 (29–43) beats/min. The respiratory rate ranged from 2.7–3.7 with a mean of 3.3±0.3 breaths/min. A pronounced sinus arrhythmia was observed. The present study provides novel data on resting free-ranging animals. The technique is simple and affordable, and may be applicable to other marine mammals.

Acknowledgments

The Commission for Scientific Research in Greenland is acknowledged for funding this research. The authors wish to thank the Danish Polar Center, the Sirius Sledge Patrol, E-Vet Denmark, and Simonsen & Weel.