Narwhal

The narwhal is a medium-sized toothed whale and the sole living relative of the beluga within the family Monodontidae. Its scientific name, Monodon monoceros, was assigned by Linnaeus in 1758 and translates as the whale with one tooth and one horn, a direct reference to the animal's single tusk.

The narwhal is placed in the genus Monodon under the scientific name Monodon monoceros, described by Linnaeus in 1758. It belongs to the family Monodontidae, which contains only two living species: the narwhal and the beluga, Delphinapterus leucas. The two are distinguished in the skull, the narwhal having a relatively short rostrum and wide neurocranium, while the beluga has a more elongated and narrower cranium.

The two monodontids are not wholly isolated from one another reproductively. A narwhal-beluga hybrid skull known as a narluga was found at Disko Bay in Greenland in 1990 by researchers. At least 57 cases of hybridization have been described in cetaceans, of which 27 were natural and 30 in captivity. Narwhals also carry remarkably low genetic diversity, a pattern that suggests a population bottleneck in their recent history.

The narwhal has a robust body and a small bulbous head with little or no beak, and it lacks a dorsal fin. Calves are about 1.60 m long and 80 kg at birth, while males can grow to 5.40 m and about 1935 kg. Females reach up to 4.94 m and about 1552 kg. Adult females can reach lengths up to 13.8 feet and 2,204 pounds, and adult males can reach 15.7 feet and 3,527.4 pounds. In a typical narwhal blubber makes up 30 to 35 percent of body weight, forming a layer 50 to 100 mm thick.

The tusk grows to more than 3 metres and is grooved on the surface in a left-handed spiral. Narwhal tusks are the only example of straight tusks in nature.

The macroscopic left-handed helix of the tusk is reproduced from mineralized collagen arranged in a molecular double helix of opposite chirality. Cementum has a left-hand helix of collagen fibrils while dentine has a right-hand arrangement across annual growth layers. The spiral pattern of the narwhal tusk is determined by the angular parameters of the arcs of the cementum layer, and the mean tangent of the angle of inclination of the spiral arcs is 2.39 in the study sample. The orientation of the twisting is oblique, indicating elongation of the spiral along the long axis of the tusk. Examination of the tusk revealed about ten million nerve endings, suggesting some sort of sensory function. In 2014 researchers discovered that the tusk is a sensory organ, and in 2017 drone footage showed narwhals stunning fish with the tusk before eating them.

Narwhals are most numerous in the eastern Canadian Arctic and along the coasts of Greenland, and they also occur in northern Svalbard and Franz Josef Land. Twelve populations are recognised on the Atlantic side of the Arctic Ocean, distributed across Canada, Greenland, Norway and Russia. In winter they reside in very heavy consolidated pack ice, using leads or polynyas to breathe. In Svalbard the species is protected, and although catches in its waters were recorded they were never in large numbers. Between 45,000 and 50,000 narwhals from the Baffin Bay population may summer in Canadian waters.

The narwhal has recently appeared more frequently in the eastern Beaufort Sea, west of its normal range. During the last Ice Age the species was restricted to the North Atlantic, and it spread across the Arctic as the ice retreated.

Narwhals feed on Greenland halibut, Arctic and polar cod, squid and shrimp, with heavy feeding concentrated in late autumn and winter on Gonatus squid and Greenland halibut; the composition of the diet differs regionally between populations, and little feeding occurs during summer. Winter diving brings them to the ocean bottom in deep water, with 5 to 25 dives per day to depths of 800 metres or more and repeated dives between 800 and 1,600 m. Maximum dive depths reach up to about 1,500 m, with dives of 25 to 30 minutes, though sources differ on dive duration.

Narwhals usually travel in groups of 15 to 20 animals, and herds of several thousand have been recorded. When threatened they move close to land or ice and form tight groups. Apart from humans, polar bears and killer whales are their dominant predators. They communicate through echolocation using clicks, whistles and pulsed calls, with recorded maximum amplitudes at 48kHz.

In summer narwhals migrate from Baffin Bay to northeastern Canada and northwest Greenland, where Inuit hunt them for subsistence. Wintering and summering areas may lie about 1,000 km or more apart. Because they must wait for cracks in the ice before moving far from open water, the spring migration is much slower than the autumn migration.

Mating in the narwhal takes place in May and June, and the calf is born the following year once the female has carried it for 11 to 15 months. Females reach sexual maturity between the ages of 7 and 9 and on average produce a single calf every 3 years. The species is among the few mammals known to undergo menopause. Narwhals are long-lived, with the longest-lived individuals possibly reaching between 105 and 125 years.

The 2017 Global Review recognized 12 narwhal stocks and compared the list with those of previous reviews. The High Arctic Cetacean Survey of August 2013 — the first survey to estimate all four Canadian Baffin Bay narwhal summer stocks in the same summer — returned the most recent abundance estimate for the Somerset Island stock, the largest, of 49,768 narwhals, and estimated 141,908 narwhals across six Canadian High Arctic stocks, with a 95% confidence interval of 102,464 to 196,536. A 2017 estimate put the global population at approximately 85,000 to 100,000 animals. The Baffin Bay population is estimated at 60,000 to 80,000 narwhals, while the Hudson population is about 5,000 animals.

The narwhal is assessed on the IUCN Red List as Least Concern, a status assigned in 2017. Populations nonetheless carry high levels of some pollutants and heavy metals such as mercury, which can affect the health of populations.

Tagged narwhals altered their diving and foraging in response to ship sounds and seismic airgun pulses, showing extreme sensitivity to human-made noise. In one study six male narwhals were tagged in Scoresby Sound in East Greenland and their acoustic data analysed. Satellite-tagging studies of narwhals in Canada and West Greenland were initiated in 1993 and have been ongoing since then.

Hunting is the most apparent man-made pressure on marine mammals in the NAMMCO region, and whaling and sealing remain a reality for many northern coastal communities where marine mammals are abundant and other resources are scarce. Struck and lost animals are included in NAMMCO hunting statistics as known or estimated values. Loss estimates from community-based hunts suggest that at least 19 and perhaps as many as 46 narwhals are lost for every 100 landed. In 2008 more than 600 narwhals were caught in the ice in Eclipse Sound and 629 were harvested.

The Canada/Greenland Joint Commission on the Conservation and Management of Narwhal and Beluga manages shared stocks, while the NAMMCO-JCNB Joint Scientific Working Group has developed a catch-allocation model to assign narwhal catches to stocks. Quotas were introduced in 2004 for West Greenland and in 2008 for East Greenland. The Government of Greenland sets quotas based on user knowledge, cultural and meat needs, and advice from the JCNB and NAMMCO. Scientific advice for West Greenland in 2022 allocated the highest catch levels to Uummannaq with 123 narwhals and 54 narwhals to Disko Bay. The 2024 quotas included 88 animals for Qaanaaq and 154 for Uummannaq. Greenland plans to bring narwhal and beluga into its new digital reporting system, prepared in 2025 for implementation the following year. In 2025 Greenland reported a narwhal catch of 400 against a total quota of 665 animals. In 2019 the NAMMCO Scientific Committee recommended that catches in all management areas in East Greenland be reduced to zero. NAMMCO member countries report catch numbers for a given year by 1st February of the following year.

Narwhals have been listed on CITES Appendix II since 1979 and exports need permits and tusks exportable only after a non-detriment finding. The uncarved tusk with a broken tip sold for between USD925 and USD2,900 on the international market. Operation Longtooth involved approximately 250 narwhal tusks legally purchased in Canada and smuggled to the United States. Tusks counted in international trade from 2005 to 2009 imply a minimum of 1,142 narwhals, an average of 228 tusks per year. Global landings averaged 979 narwhals per year from 2007 to 2011 (621 in Canada and 358 in Greenland. Canadian landings from 1988 through 2001 averaged 327 narwhals annually from the Baffin Bay population and 40 from the Hudson Bay population. In 2002 the annual harvest limit for Repulse Bay was reduced from 100 to 72 narwhals. The United States Marine Mammal Protection Act of 1972 prohibited the import of narwhal parts.

Hunted narwhals supplied more than their tusks: their blubber and oil were used for lighting, heating and cooking, while sinews served as thread. King Frederik III of Denmark-Norway ordered a coronation chair made entirely from narwhal tusks, completed in 1671 as a sign of power and status. Ole Worm's Museum Wormianum of 1655 describes skulls of a marine unicorn and concludes that unicorn horns must come from narwhals.