Narwhal (Monodon monoceros) COSEWIC assessment and status report: chapter 5
Habitat
Habitat requirements
Narwhals inhabit a vast area of the Arctic, but little is known of their actual habitat requirements. In summer, they show preference for coastal areas that offer deep water and shelter from the wind (Finley 1976; Kingsley et al. 1994; Richard et al. 1994). Remote sensing studies suggest that they may prefer to locate near thermal boundaries that are created by upwellings and frontal areas where water masses meet (Barber 1989). However, blubber loss by female narwhals suggests that their summer habitat selection may be related more to calving requirements than feeding opportunities (Finley and Gibb 1982). During their fall migrations, and later while wintering in the pack, narwhals show preference for deep fjords and the continental slope, where depths range from 1000 to 1500 m and upwellings may increase biological productivity (Dietz and Heide-Jørgensen 1995; Dietz et al. 2001). The quality of the ice habitat, particularly the presence of leads in fast ice and the density of broken pack ice, appears to be a key aspect of their habitat selection (Koski and Davis 1994). The ice may also provide refuge from predation by killer whales.
Trends
The potential effects on narwhal populations of changes in ice habitat resulting from climate change have not been evaluated. This is an important question since the species’ range and distribution may be directly related to long-term temperature fluctuations and the resultant ice cover (Vibe 1967).
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