Diving behaviour of hooded seals (Cystophora cristata) in the Greenland and Norwegian Seas

Satellite-linked dive recorders were used to collect data on depths and durations of similar to 120,000 dives by 16 hooded seals (Cystophora cristata). Following tagging after moult (four males, eight females) and breeding (four females) off east Greenland, seals dispersed widely in the northeast Atlantic during 172 +/- 97 days (mean satellite-linked dive recorder lifetime +/- SD). Meso/bathypelagic dives of 5- to 25-min duration to 100-600 m dominated (75%), but some very deep (greater than or equal to 1016 m) and long (>52 min) dives occurred. Diving in open ocean was continuous, with an estimated 90.7 +/- 0.8% (mean +/- SE) of time spent submerged. The proportion of time spent submerged was similar during night and day, but dives during the day were generally deeper and longer (P < 0.05) than during the night. Also, dives in winter were deeper and longer than in summer. Published data on the distribution of likely prey suggest that Greenland halibut (Reinhardtius hippoglossoides), redfish (Sebastes spp.), polar cod (Boreogadus saida), herring (Clupea harengus), squid (Gonatus fabricii) and blue whiting (Micromesistius poutassou) are important prey of hooded seals.