Diving patterns of harbour seals ( Phoca vitulina ) in the Wadden Sea, the Netherlands and Germany, as indicated by VHF telemetry

• Published in: Canadian Journal of Zoology
• Main Authors: Ries, Edith H., Paffen, Petra, Traut, Ilona M., Goedhart, Paul W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1997
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Phoca vitulina
• Online Access: http://dx.doi.org/10.1139/z97-840; http://www.nrcresearchpress.com/doi/pdf/10.1139/z97-840

The diving behaviour of 25 harbour seals, Phoca vitulina (14 females and 11 males), of various body lengths was monitored by means of VHF telemetry at different locations in the Wadden Sea during late autumn in 1991 and 1992. Median dive durations for individual seals ranged from 46 s to 2.9 min. The maximum dive recorded was 31 min, performed by an adult male, which represents the longest dive reported for harbour seals. Dive endurance increased significantly in relation to body length. Female harbour seals tended to perform fewer short dives and had a more narrow distribution of dive times. We detected no diurnal differences in dive behaviour and only the ambient air temperature was found to influence the duration of surface periods, in that surface intervals tended to be shorter when temperatures were below 9 °C. The overall mean percentage of dive time was 85%, with individuals varying from 76 to 93%, and was in general higher in females.