The narwhal is one of three species of whales (along with beluga and bowhead whales) that spend their entire lives in cold Arctic waters. They are perhaps the most “Arctic” of whales, being found exclusively in areas of the Arctic that are seasonally covered by land-fast or pack ice. They can be found further north and in areas that are inaccessible to other Arctic whale species. They are almost always associated with sea ice, except during late summer in some areas.
During the fall, winter and early spring the narwhal lives in dense pack ice, using leads and polynyas (open water areas within pack ice) to breathe. In the spring, narwhals follow the receding ice pack and spend the summer usually in shallower waters closer to land, often within fjords or close to glacier fronts.
Summer (solid colours) and winter (hatched) distribution of narwhals in Greenland and Canada
Narwhal distribution around Svalbard, Novaya Zemlya and Franz Josef Land
Much has been learned about the physical and seasonal habitat of narwhal through the application of satellite-linked tags. In such studies, narwhal are captured in nets and the tags are attached either to the tusk (in male narwhal) or by bolts through the dorsal ridge. The tags transmit data when the narwhal surfaces. Along with location, tags can collect data on diving and the time spent at specific depth intervals. To date tagging studies have been conducted on almost all summer aggregations of narwhal in Canada and Greenland (Heide-Jørgensen et al. 2013b) and at Svalbard (Lydersen et al. 2007). Read more in Research in NAMMCO member countries.
Narwhal begin migrating as early as late March or early April, following the receding ice pack into areas inaccessible in the winter. At this time of year they can be found at ice edges in the Canadian Eastern Arctic, West and East Greenland and Svalbard. Narwhal tend to spend more time near the surface and travel farther each day during the spring (Laidre et al. 2004).
During the summer narwhal can be found closer to land and in shallower water than at other times of the year (Laidre et al. 2004, Heide-Jørgensen et al. 2013ab). They move into areas of the Canadian Eastern Arctic, West and East Greenland, and Svalbard that are covered by landfast ice and inaccessible at other times of the year. During this period narwhal often congregate in fiords and at glacier fronts, and form larger groups than in other periods, up to several hundred animals.
The return to wintering areas begins in late September or later, depending on when the sea ice begins to form. Fall movements are often quite rapid although narwhal may occupy other coastal areas that remain ice-free for periods at this time of year (Heide-Jørgensen et al. 2013ab). They reach their wintering grounds by November or early December.
|Watch a video showing narwhal migration patterns and sea ice!|
In the winter, narwhal occupy areas covered with heavy pack ice over water up to 2000 m in depth. In Baffin Bay they spend the winter in areas with as little as 0.5% open water (Laidre and Heide-Jørgensen 2005a).
Sea ice with an open water leads in Labrador, Canada. Photo: Wikipedia
The general pattern of seasonal habitat use is similar for all populations that have been tracked so far. During the winter narwhal occupy areas covered with heavy pack ice over water up to 2000 m in depth. In Baffin Bay they spend the winter in areas with as little as 0.5% open water (Laidre and Heide-Jørgensen 2005a), diving repeatedly to depths of up to 1600 m to feed on fish at or near the sea bottom. Narwhal are physiologically adapted for long dives, having a very high ratio of slow oxidative to fast twitch muscle fibres, and by having the highest levels of myoglobin recorded in any marine mammal, giving them exceptional oxygen storage capacity (Williams et al. 2011). They can dive aerobically for up to 24 minutes, giving them the ability to feed at great depths and move up to 1.4 km between breathing holes.