sign in sign up
<<
Home , Narwhal, Sperm whale, Whale

Scientific Excellence • Resource Protection & Conservation • Benefits for Canadians

The 2 Underwater World

triangular. Mature are white, , keras, a ). Some males also with a darker and a dark strip grow a on the right side as well, The Narwhal down the back. On either side of the usually shorter than the other, and occa- strip, dark flecks and spots become sionally, an abnormal tooth grows out sparser toward the flanks. This pallid, of the tip of the lower jaw of a narwhal. Kingsley mottled colouring, said to be like that After the tusk has reached its final of the body of a drowned man, is sup- length, its walls continue to thicken Department of and posed to be the source of the common inwardly, as the living pulp runs the full Institut Maurice-Lamontagne name, from nar, corpse, and length of the hollow tusk. Perhaps nar- P.O. Box 1000, 850 route de la Mer hvalr, . The narwhal is insulated whal , arriving in by little- Mont-Joh, G5H 3Z4 from the freezing waters it inhabits by used trade routes, originated the legend a layer of — fatty tissue under of the ; certainly as trade routes the — up to 10 cm thick. improved in the Middle Ages, thousands The most common external parasites of narwhal tusks were sold for more Relatives Among the ; are whale lice Cyamus monodontis and than their weight in in Europe as Description C. nodosus. They are found in patches unicorn horns or "alicorns", for their where wounds have given them a foot- supposed magical properties, by traders The narwhal is a "", a hold, although many wounds heal with- who were at some pains to suppress the member of the Odontoceti (Gr. out becoming infested. A ring of louse knowledge that these fabulous panaceas odous, a tooth, ketos, a whale), a infestation is always found in males were no more than whales' teeth. relative of the ( around the base of the tusk, where it It is still uncertain whether the tusk macrocephalus), pilot whales, breaks through the lip. Small numbers is more to the male narwhal than an and . It is unusual among the of nematode worms are found in the advertisement of mature sexuality. It has whales, as it has no dorsal , and its , and nematode infections of been suggested that the narwhal uses it neck vertebrae, instead of being fused the middle ear are also common. for spearing , stirring up the bottom, together, are jointed like those of land breaking ice, as a wave-guide for its . The beluga, Delphinapterus The Unicorn of the underwater vocalizations and even for leucas, which like the narwhal is found propping itself up on ice floes to go to in icy seas, shares these charac- One difference between belugas and sleep. Broken and worn tusks are teristics; the fin may have been lost narwhals is in their teeth: belugas have common, but this probably shows no because it was a hindrance under ice. a mouthful of peg-like teeth, but nar- more than the difficulty of taking care Because of these, and other, shared ana- whals have no functional teeth at all. of 7 feet of when chasing food tomical features, the two were classified Two elongated teeth develop in the near the bottom in dark water. That it in the same family, the , upper jaw, but they point forwards, not is not needed for survival is shown by separate from other odontocetes. Recent down into the mouth. In females, both the female's not having one. It may be biochemical studies have confirmed usually remain embedded in pockets in used as a weapon by the males in fight- their close relationship. Both also have the maxillary bone, and grow no longer ing for females, but as mating takes a short, broad ; a melon — the than 15 cm or so, but in the males, and place in spring when narwhals are in the hemispherical body of fatty tissue a very few females, the left one erupts offshore pack-ice, their mating situated in front of the cranium — that through the lip and develops as a behaviour is unknown. Scars found on is pronounced, forming a steep forehead straight, spiral, tapered tusk, with a left- the foreheads of mature males have been with no visible beak; and small, hand twist, 2.0 to 2.5 m long. From this cited as evidence for this use, and so rounded, up-curved flippers. extraordinary feature, unique among have such findings as a tusk point once Among the toothed whales, both the the whales, Linne gave the narwhal its discovered embedded in a male's jaw narwhal and the beluga are large: aver- scientific name of Monodon monoceros beside the root of the growing tusk. age males weigh about 1.6 tonne and are "the one-toothed that's like a Males are seen in summer lifting their about 4.6 m long, females weigh about monos, single, odous, a tusks out of the water and crossing them 0.9 tonne and are about 4.0 m long. unicorn" (Gr. Narwhals have blunt heads and small mouths, and are sleeker than beluga, which look blubbery and lumpy in comparison. On small-scale aerial photographs narwhals may be distin- guished from belugas by: their lack of visible flippers; lack of squared shoul- ders; caudal peduncle fine to the point of being invisible; and recurved fluke tips, where the beluga's tail is more The narwhal. (Line drawing courtesy of Larry Foster, Alameda, CA 94501, USA.) Underwater World 3

with the tusks of one or two other males; mammals, narwhals have only one head thrown up to breathe with a jerky but whether this "tusking" has to do at a time. The newborn have only bob, quite unlike the smooth curve with establishing social dominance, or very thin blubber, but the mother's milk of an adult, is unmistakable. The new- is just a way of passing a summer after- is rich in fat and a thicker blubber layer born calves, 1.6 m long, are uniform noon, is unknown. is soon laid down. Calves are nursed for dark grey; white patches.later appear on 20 months; other odontocetes also have the ventral surface and spread with long , perhaps to give their increasing age to the flanks and back. Population Dynamics and calves time to learn the skills they need to survive. The association of mother The death rate among adults is r Females probably start bearing calves and calf is usually close, and when the probably quite low — 7 to 9%/yr — and at 6-8 years of age. They mate in April- whales are travelling the calf remains the mortality of the young unknown. May, and gestate for 14 months, bearing close to the mother's back, where it may The late and slow reproduction means their calves in June-August of the get hydrodynamic assistance. In a that numbers of narwhals, once following year. Like all other marine travelling group of whales, the little grey reduced, could only increase slowly.

LLCSMIERC ISLAND

ci

REPULSE BAY

Range of narwhal in eastern Canadian and West waters. Wintering areas cross-hatched. Summering concentrations in black: (A) Eclipse Sound, Milne Inlet and Tremblay Sound; (B) Admiralty Inlet; (C) Prince Regent Inlet; (D) Peel Sound; (E) Repulse Bay. (Courtesy of Mr. J. T. 0. Strong, DFO, Winnipeg.) 4 Underwater World

Distribution, Movements, and Numbers summer as far northwest as Lougheed Island. It seems as though, by choosing The narwhal inhabits ice-covered particular areas in these restricted Arctic seas, only rarely wandering into waters, they can find shelter from rough temperate waters. In ice-free waters, it seas (which perhaps, living in pack ice is more likely to be preyed upon by killer of other times of year, they are not whales (Orcinus orca), and would have accustomed to) or places to stay away to compete for food with other from killer whales, from which at other of whale better adapted to warmer times of year the ice offers some pro- conditions. It has no to hinder tection. When the days shorten in it in swimming under the ice, and can September, and seas start to freeze, break several centimetres of ice with its narwhals head out again into Baffin forehead. Narwhals can travel miles Bay. Herds are sometimes trapped in the under the ice between breathing forming ice; then tens or hundreds may opportunities, and can use even the crowd at a single contracting hole in the breathing holes made in the ice by ice, where they may become prey for the Arctic seals, surfacing head first polar bears (Ursus maritimus) or . and then sliding back underwater. In The narwhal is also found in other Canadian waters, narwhals winter in the parts of the Arctic: in the waters of West close pack ice of and Davis Greenland, and in the northern Atlantic. Strait, between and Although not unknown, it is uncommon Greenland. As the ice melts in spring, in the Bering, Beaufort and Chukchi they migrate northward up the east coast seas, and in the seas to the north of of Baffin Island. Herds of hundreds, Siberia. heading north and west, round off the northern end of Baffin Island and crowd at the edges of the fast ice in , and Jones Sound. As these ice edges retreat with the onset of summer, narwhals penetrate and cracks into Eclipse Sound, Navy Board Inlet, Admiralty Inlet, and Prince Regent Inlet, and as the ice melts, they tend to stay associated with it. About 1200 narwhal are also found in summer in northwest ; they are probably a separate group wintering in . Photo- graphic aerial surveys of the main summering areas have estimated the total number inhabiting Canadian waters in summer to be about 20 000. Narwhals summer in the Thule area of northern West Greenland, and over 4000 have been counted there. It is not known whether the groups in the different in summer are always the same, or whether they exchange members on the wintering grounds. At the height of summer, narwhals are found in greatest numbers in the fjords of northern Baffin Island, moving from place to place in herds of hundreds, but other groups are also regularly found in Peel Sound between Somerset Island and Prince of Wales Island, and narwhals have been seen in Narwhal often associate in tight groups. (Photo courtesy of Larry Dueck, DFO, Winnipeg.) Underwater World

Food and Feeding What information we have on the diet of the narwhal relates mostly to the summer, between the time when nar- whals appear at the fast-ice edges and their disappearance in fall. The narwhal has no functional teeth, but it has a wide rostrum and a ridged palate. All these features are thought to be typical of whales that live mostly on , and the food species that has been found most consistently is a squid, Gonatus Narwhal stomachs have been examined that were packed full with squid, and others that contained hundreds or thousands of squid beaks, which stay long after the rest of the squid is digested. Other important food species are: the Arctic cod, , a small relative of the familiar food fish, which the narwhal feeds on heavily at the ice edges in spring; turbot or , Rheinhardtius hippoglossoides; and a pelagic Pasiphaea tarda. There is no indication that narwhals feed heavily on Arctic char (Salvelinus alpinus). From the evidence of stomach contents, adult male narwhals feed more on bottom- dwelling species such as than the females or young; unhindered by accompanying calves, they can dive deeper and faster, and stay down longer. There is no information on how much narwhals eat in the wild, but a whale of such size should need about 30 kg (wet weight) of food a day. It has been sug- gested that narwhals eat less in the summer and loses some weight then, but narwhals have been observed in August engaged in deep diving behaviour typical of feeding, and summer blubber loss is only slight. Feeding narwhals spread quite widely and dive independently; they don't seem to hunt cooperatively for prey. Although there have not been any direct observations of how deep nar- whals can dive, they have been found Examples of tusk display behaviour. Note the pronounced melon. (Photos courtesy with bottom-dwelling flatfishes in their of Larry Dueck, DFO, Winnipeg.) stomachs from over 800 m of water. They have good adaptations for deep diving, such as and muscle tissue with -holding capacities well- developed even for a whale, and a complex network of blood-vessels between the lungs and the spine. 6 Underwater World

Between deep feeding dives narwhals lie still in the water breathing deeply to replenish their oxygen stores. As the whale breathes in, the long grey back rises in the water, and then the is closed for a while, before an explo- sive exhalation and the next indrawn breath. When it has finished ventilating, it starts to swim forward, rising and falling in the water with increasing amplitude as it accelerates. The last high rise in the water, in which the head is often thrown almost clear, is followed by a deep dive, with pronounced flexure of the body and the tail stock, as the whale submerges; narwhals often, but not always, fluke out when starting a deep dive.

Sound and Communication It is hard to see very far in the , but sound travels well, and narwhals, like other odontocetes, have evolved complex and sophisticated systems to A group of younger males. The leading one is a dark subadult. Note the neck use sound to investigate their environ- articulation shown by the upper one. (Photo courtesy of Larry Dueck, DFO, ment and to find food. By the controlled Winnipeg.) passage of air between chambers near the blowhole, the narwhal can create clicks and whistles. These sounds are reflected off the sloping front of the and focused by the melon, which is filled with a special mix of blubber oils and can be altered in shape under muscular control. Clicks and knocks can come slowly, like knocks on a door, or in faster sequences, like a stick on a picket fence, or in very rapid trains that can produce a trumpeting blare or the sound of a squeaking door. Click trains are used by odontocetes for echo- Behaviour be almost touching. Such tight groups location of prey, and for detecting vocalise little, if at all. Travelling herds obstacles, at short ranges. Individual This whale is in general a placid may adopt more open distributions, and bangs may also be strong enough to dis- species, little given to spontaneous are then more vocal, giving click series orient or incapacitate prey and make it exuberance. Its normal swimming speed and trumpetings. Narwhals on the easier to catch. Whistles are rarely heard is low. As it is in general a social species, summering grounds seem to spend much — another contrast with the beluga, few individual behaviour patterns have time loafing, logging (i.e. lying inactive which whistles so much that it earned been recorded. The usual social unit is at or below the surface), and socialising, the nickname "sea canary". The nar- a group of 2 to 12. Groups often consist and a wide variety of behaviour patterns whal's repertoire of whistles is small, only of adult males, or only of sub- have been observed and recorded. Males and they are usually short, and simply adults and females with young, but in particular display to each other, modulated as a single upward or down- mixed groups do sometimes occur. crossing and "comparing" their tusks. ward glissando. Trumpetings, whistles, There is no information on how long However, there is no information on the and squeaking-door sounds may be used these groups last, nor whether they social significance of these behaviour for communication. Males have the represent enduring social bonds. When patterns, nor on the functional structur- larger vocal repertoire, and make a wide travelling, these groups may be tightly ing of narwhal society. range of calls when socialising. cohesive: the individuals often seem to Underwater World 7

Exploitation and Management The total quota for the Canadian Arctic and some of the adjacent fjords have is 527 yearly. Tags authorising recently been studied by flying repeated Narwhals are hunted by the Inuit of a hunter to take a whale are distributed aerial surveys over the same track every the Canadian Arctic and in Greenland. in the communities by the local Hunters' 3 or 4 days. By observing where the The skin, known as "", is an and Trappers' Associations. The aver- narwhal go as the ice melts or moves, esteemed food — especially the narrow age estimated kill in in recent or as the wind or weather change, scien- strips taken from the back edges of the years is 450-500. tists have been trying to deduce what tail and flippers — and is eaten raw or factors make them select the areas they boiled. It is rich in . The Current Research do. is often left in a cache to age through Also recently studied have been the the summer and fall, and is eaten as Some areas of recent research on the reactions of narwhal to ice-breaking ore- cured meat in the winter. narwhal have been the search for a relia- carriers which come into the eastern ble way to age individuals, so that more Canadian Arctic in early summer: The tusks at one time commanded a and better information on the popula- whether they show signs of alarm, flee, high price on international markets. tion dynamics can be obtained. Layers or change their vocalization patterns. To Narwhal, like other toothed whales, are in teeth are often used to age animals, compare with such results, the undis- listed in Appendix II of the Convention but although the embedded teeth in turbed vocalizations of narwhal have on International Trade in Endangered narwhal do have layers, they become been recorded in one of the narrow Species, so trade in tusks requires an confused once the tooth has grown to fjords where they summer, while their export permit. Even so, concern for the fill the maxillary pocket that encloses it. behaviour was simultaneously observed species has led the European Economic Tusks have readable layers, but sawing from the top of a cliff. This has helped Community to ban the import of tusks a tusk in half is not only an expensive to show which sex or age-groups give into member states (tusks taken by the way to age a narwhal, but cannot be particular vocalizations, and what they Inuit of Greenland are exempted). used to age females. Scientists have might be doing at the time, and so inter- Inuk villages where narwhals occur looked for layers that may be related to pret the communication function of the have quotas on how many they can take, age in other hard structures, such as various calls; and to indicate whether which range from 100 in Arctic Bay and bones, and have examined age-related vocalizations might be usable to tell the Pond Inlet in north Baffin Island where changes in the amino-acid composition numbers of narwhals at times or in narwhals come in great numbers every of the tip of the embedded tooth. places where they can't be counted year, to 5 or 10 for communities away The movements of the narwhal within visually. from the zone of greatest abundance. their summering areas in Eclipse Sound A research activity that has recently started is to monitor the movements of narwhal using tusk-mounted radios that transmit signals to orbiting satellites. As well as yielding information on move- ments of the whales in their summering areas, this could also allow it to be tracked into the dark and cold of the Arctic winter. More complicated tags, capable of storing, and then transmit- ting, information on how deep, and how often, a narwhal dives, could provide valuable information on underwater behaviour.

Inuk hunters removing muktuk. (Photo courtesy of Larry Dueck, DFO, Winnipeg.) 8 Underwater World

Further reading Hay, K. A. and A. W. Mansfield. 1989. Pilleri, G. 1983. In Baffin Land to study the Narwhal — Monodon monoceros narwhal (Monodon monoceros). Verlag Arvy, L. 1978. The narwhal (Monodon Linnaeus, 1758, p. 145-176. In S. H. des Hirnanatomischen Instituts, Oster- monoceros L.). Acta Zool. Pathol. Ridgway and R. J. Harrison [ed.] mundigen, Berne (Switzerland), 102 p. Antverp. 73: 43-118. (Transl. from Handbook of Marine Mammals, (Transl. from German. Can. Transl. French. Can. Transl. Fish Aquat. Sci. Volume 4: River Dolphins and the Fish. Aquat. Sci. 5192, 1985, 140 p.) 5342, 1988, 107 p.) Larger Toothed Whales. Academic Press, San Diego, CA. Reeves, R. R., and E. D. Mitchell. 1981. The Bruemmer, F. 1989. Ancient spell of the sea whale behind the tusk. Natural History unicorn. International Wildlife 19(6): Kingsley, M. C. S. 1989. Population 90(8): 50-57. 38-43. dynamics of the narwhal Monodon monoceros: an initial evaluation Silverman, H. 1979. Social organisation Hay, K. A. 1984. The life history of the (Odontoceti: Monodontidae). Journal and behaviour of the narwhal, narwhal (Monodon monoceros L.) in of Zoology 219: 201-208. Monodon monceros L., in Lancaster the eastern Canadian Arctic. Ph.D. Sound, Pond Inlet, and Tremblay thesis, Institute of Oceanography, Kingsley, M. C. S., and M. A. Ramsay. Sound, Northwest Territories. M.Sc McGill University, Montreal, Quebec. 1988. The spiral in the tusk of the thesis, McGill University, Montreal, 255 p. (Unpublished.) narwhal. Arctic 41: 236-238. Quebec, 144 p. (Unpublished.)

Published by:

Communications Directorate Department of Fisheries and Oceans Ottawa, Ontario Underwater World factsheets are brief K1A 0E6 illustrated accounts of fisheries resources and marine phenomena pre- DFO/4284 UW/61 pared for public information and edu- cation. They describe the life history, © Minister of Supply and Services geographic distribution, utilization and Canada 1990 population status of fish, shellfish and Catalogue Number Fs 41-33/61-1990E other living marine resources, and/or ISBN 0-662-17907-2 the nature, origin and impact of marine processes and phenomena. Aussi disponible en francais

Others in this series: Alewife Atlantic Shellfish Marine Fish Eggs and Selected Freshwater Fish Think Recycling! American Eel Atlantic Snow Crab Larvae Selected of American Oyster Bluefin Northern Shrimp British Columbia American Plaice Pollock Soft-Shell Clam American Shad Cetaceans of Canada Red Hake Spiny Dogfish American Smelt Crabs of the Atlantic Urchin Squid Arctic Char Coast of Canada Red Tides Thorny and Smooth Arctic Cod Dungeness Crab Redfish ( Perch) Skates Pensez a recycle.! Trout in Canada's Atlantic Cod Grey Seal Rockfish Printed on recycled paper Atlantic Fishing Methods Haddock Roundnose Grenadier Atlantic Provinces Atlantic Groundfish Irish Moss Sand Lance Turbot (Greenland Halibut) Atlantic Halibut Lake Trout Sea Cucumber Walleye Atlantic Lingcod Sealing — A Canadian White Hake Atlantic Mackerel Lumpfish Perspective Winter Flounder Atlantic Pelagic and Sea Scallop Witch Flounder Diadromous Fish Yellowtail Flounder Atlantic Salmon