Extreme diving of beaked whales

摘要: Sound-and-orientation recording tags (DTAGs) were used to study 10 beaked whales of two poorly known species, Ziphius cavirostris (Zc) and Mesoplodon densirostris (Md). Acoustic behaviour in the deep foraging dives performed by both species (Zc: 28 seven individuals; Md: 16 three individuals) shows that they hunt echolocation water between 222 1885 m, attempting capture about 30 prey/dive. This food source is so average deeper 1070 m; 835 m) longer 58 min; 47 min) than reported for any other air-breathing species. A series shallower dives, containing no indications foraging, followed most dives. The interval was 63 min Zc 92 Md. long an may be required recover from oxygen debt accrued which last twice estimated aerobic dive limit. Recent reports gas emboli stranded during naval sonar exercises have led hypothesis their deep-diving make them especially vulnerable decompression. Using current models breath-hold diving, we infer natural diving inconsistent with problems acute nitrogen supersaturation embolism. If assumptions these are correct whales, then possible decompression more likely result abnormal behavioural response sonar.