Diving behaviour of narwhals (Monodon monoceros) on their summer grounds

摘要: Three adult female narwhals from the population that summers in sheltered waters of northern Baffin Island, Canada, were fitted with satellite-linked UHF radio packages. The units logged and transmitted diving swim-speed data revealed location study animals for periods up to 19 days. Most activity was top 40 m bottom water column. Shallow dives characterized by low rates descent ascent (<0.5 m∙s−1), short submersions, frequent changes vertical direction. Deep normally to, or near seabed depths 257 m, involved both faster movement (1–2 m∙s−1) longer underwater (up 15.1 min). Midwater intermediate all respects. Deeper a characteristic "square" profile provided an average 7 min at chosen depth, representing 57% time submerged. No demonstrably than estimated aerobic dive limit this species. Activit...