Narwhal (Monodon monoceros) COSEWIC assessment and status report: chapter 2

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Executive Summary

Species information

Narwhals (Monodon monoceros) are medium-sized toothed whales that lack a dorsal fin. They are about 1.60 m long at birth (80 kg). Males can grow to 5.40 m (~1935 kg) and females to 4.94 m (~1552 kg). Adult narwhals have only two teeth. In most males, the right tooth remains embedded in the skull and the left forms a magnificent spiral tusk that can extend straight forward over 3 m.

Distribution

Two of three recognized populations of narwhals occur in Canada (Baffin Bay and Hudson Bay). The third occurs in East Greenland. The populations are distinguished by their summering distributions, which may not reflect the degree of interchange between them. The East Greenland population is not thought to enter Canadian waters. Narwhals from the Baffin Bay population summer in the waters of West Greenland and the Canadian High Arctic, and winter in Baffin Bay and Davis Strait. They range over an area of at least 1.25 million km². The degree of site fidelity within this shared population is unknown and it may in fact consist of several populations. Narwhals that summer in northwest Hudson Bay are believed to winter in eastern Hudson Strait and range over an area of roughly 250,000 km². The population affinity of animals that summer north of Baffin Bay and along the eastern and southern coasts of Baffin Island is unknown. Biologists have not identified any large-scale changes in the seasonal distribution of narwhals, but Inuit have observed local changes.

Habitat

Narwhals inhabit a vast area of the Arctic, but little is known of their actual habitat requirements. In summer, they prefer coastal areas that offer deep water and shelter from the wind. During their fall migrations, and later while wintering in the pack ice, narwhals prefer deep fjords and the continental slope, where depths range from 1000 to 1500 m and upwellings may increase biological productivity. The quality of the ice habitat, particularly the presence of leads in fast ice and the density of broken pack ice, appears to influence habitat selection.

Biology

The vital rates of narwhals are uncertain because there is no accurate method to determine their ages. Females are believed to mature at 5 to 8 years and produce their first young at 7 to 13 years. Mating peaks in mid-April, and most calves are produced in July and August after a gestation period of 14 to 15.3 months. While more frequent reproduction is possible, mature females produce a single calf about every three years on average until perhaps 23 years of age. Longevity may be about 50 years, but most animals probably do not reach the age of 30. Generation times and net recruitment rates for narwhals are unknown. Rates of mortality from hunting are imprecise because numbers that are struck and losses is uncertain, and rates of predation by killer whales and polar bears are unknown. Little is known of the diseases of narwhals and their response to pathogens. The potential for large-scale mortality due to entrapment by ice or to disease is also unpredictable.

Narwhals generally travel in small groups in summer (<10 individuals), but gather in concentrations of many hundreds of animals during migrations in the spring and fall. Their diving ability enables them to move long distances under water and makes it difficult to obtain accurate population estimates. Narwhals eat a variety of fishes and invertebrates. Little is known about the physiological requirements of narwhals or their ability to adapt to environmental change or shifts in prey availability.

Population sizes and trends

A good estimate of the initial size of the Baffin Bay and Hudson Bay narwhal populations cannot be generated from historical harvest data. Estimates of population size have generally been limited to methods that only estimate a portion of the population. Past surveys based on aerial surveys of areas of aggregation seldom accounted for narwhals that were submerged beyond view, missed by observers because of ice or poor visibility, or were outside the survey area.

In 1996, a systematic aerial survey of Prince Regent Inlet, Barrow Strait and Peel Sound estimated 45,358 narwhals (95% CI = 23,397-87,932). This estimate was corrected for submerged animals and those missed by observers. It compares well with estimates from surveys conducted in the mid-1980s, but the statistical power to detect a trend is low. Between 45,000 and 50,000 narwhals from the Baffin Bay population may summer in Canadian waters.

The narwhal population in Hudson Bay was estimated at 1,355 (90%CI = 1000-1900) animals in 1984 and 1,780 (90%CI = 1212-2492) animals in 2000. Neither estimate corrected for submerged animals or weather conditions, and the latter included northern Lyon Inlet and Foxe Channel. The Hudson Bay population may be about 3,500 animals in summer.

Limiting factors and threats

Narwhal populations in Canada may be limited or threatened by hunting, environmental contaminants, climate change, and industrial activities such as commercial fishing. The effects of climate change on ice habitats used by narwhals are uncertain, as is the species’ capacity to adapt. The effects of the other factors are mitigated by the species’ deepwater habits and widespread geographical distribution, much of which is outside normal hunting areas in offshore pack ice and in isolated areas of the Arctic. This remote distribution protects many narwhals from hunters as well as isolated oil spills or other events. However, under exceptional circumstances, such as large ice entrapments or when killer whales drive narwhals into shallow water, many animals can be taken at once from a single locality. Hunting probably represents the most consistent limiting factor to narwhal populations in Canada.

Special significance of the species

Narwhals historically provided important staples in the traditional subsistence economy of the eastern Canadian Arctic and Greenland. Hunting and sharing of its proceeds continue to be of great social and cultural significance for some communities. Narwhals are harvested mainly for their maqtaq and ivory. The ivory commands high prices and is marketed internationally, while the maqtaq is consumed locally or traded to other Inuit communities. It is a highly-valued food and demand often exceeds supply. Ecologically, the narwhal is important as it is the only species in its genus and is an apex predator in the Arctic food chain. It generates avid public interest because of its unique “unicorn” tusk and the remoteness of its habitat, but has not been successfully displayed in captivity.

Existing protection or other status designations

Protection for narwhals in Canada is limited to measures that manage the hunt, live capture, and movement of narwhal products. The Nunavut Wildlife Management Board is the main instrument of wildlife management in Nunavut. The Department of Fisheries and Oceans is a co-management partner who provides scientific advice and regulatory support. Other co-management partners are the Hunters and Trappers organizations and the Regional Wildlife organizations. Only Inuit can hunt narwhals and limits are placed on the number of animals each community can land. The species is listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Canada cooperates with Greenland in the conservation of shared narwhal populations. The Joint Commission on Conservation and Management of Narwhal and Beluga has not been able to determine the status of narwhal populations using the data available and Canada and Greenland are conducting surveys to collect new data.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5^th 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The Committee meets to consider status reports on candidate species.

Definitions (November 2004)

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and it is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for atleast 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)^Footnotea

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)^Footnoteb

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)^Footnotec.1

A wildlife species for which there is inadequate information to make a direct, or indirect, assessment of its risk of extinction.