The Bowhead Whale (Bering-Chukchi-Beaufort Sea Population)

This species has been identified as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). It is listed under the federal Species at Risk Act (SARA) and was afforded protection under the SARA as of December 2007. Additional protection is afforded through the federal Fisheries Act. Under the SARA, a management plan must be developed for this species.

General Description

Balaena mysticetus

Illustration by G. Kuehl
© Fisheries & Oceans Canada

Bowhead Whales (Balaena mysticetus) are large baleen whales of the Balaenidae family. Other common names include the Greenland Whale, Greenland Right Whale and Polar Whale. In northern Aboriginal languages, it is known as Arviq or Arvik (Inuktitut and Inuvialuktun), Agkhovik (Inupiat), Akhgvopik (Yupik) and Ittiv (Chukchi). Bowhead Whales have the following characteristics:

• Barrel-shaped body and a very large head (about 30% of total body length)
• Upper jaw is bowed sharply upward; each side of upper jaw has on average 330 baleen plates up to 427 cm long
• The blubber layer is thick, from 5.5 cm on the chin to about 28 cm over the trunk reaching a maximum of 50 cm
• Flippers are small and paddle-shaped
• No dorsal fin or dorsal hump
• Flukes are pointed at the tip
• Calves are 4 to 4.5 m long at birth and brownish black in colour
• Adults are black in colour with white areas near the chin, eyelids, flipper insertions, ano-genital area, tail stock and flukes

Distribution

The Bowhead Whale has a nearly circumpolar distribution in the northern hemisphere and ranges from 54^o to 85^oN latitude. Physical barriers such as land and impassable ice are believed to have divided the world’s bowheads into five populations, three of which occur in Canada. The extent of occurrence of the Bering-Chukchi-Beaufort Sea population in Canadian waters is roughly 207,000 km². Whales in this population winter in the western and central Bering Sea where there is adequate open water and broken pack ice. In the spring, the whales migrate north and east to the eastern Beaufort Sea. In summer, the whales are distributed mainly in the Canadian Beaufort Sea, along the south and west coasts of Banks Island, in Amundsen Gulf, and along western Tuktoyaktuk Peninsula. In fall, Bowhead Whales migrate from the Canadian Beaufort Sea into the Alaskan Beaufort and Chukchi Sea, and then into the Bering Sea.

Bowhead Whale Distribution: Bering-Chukchi-Beaufort Sea

Habitat and Life History

Bowhead Whales occur in marine waters within areas ranging from open water to thick, unconsolidated pack ice. They break through ice over 20 cm thick with the crown of the head to breathe, and can navigate and communicate under extensive ice fields using their sophisticated acoustic sense. They grow and develop slowly, reaching sexual maturity at about 25 years of age. Females grow faster than males and give birth approximately once every three years during the spring migration. Gestation lasts between 12 and 16 months. Longevity is estimated to be between 50 and 75 years, with some individuals possibly reaching over 100 years of age.

Diet

The Bowhead Whale feeds on crustacean zooplankton such as euphausiids and copepods. Epibenthic organisms (mysids and gammariid amphipods) are also consumed. It has been suggested that the annual variability in Bowhead Whale sightings is related to the abundance and distribution of zooplankton. 

Threats

Commercial whaling was once the greatest threat to the Bowhead Whale and the main reason why the species is at risk in parts of its range. At present, the Killer Whale (Orcinus orca) may pose the greatest threat. Bowhead Whales are known to be displaced for short periods of time by industrial activity such as oil and gas exploration and development. Potential long-term effects on Bowhead Whales are unknown. Lastly, climatic factors, which influence ice conditions and prey availability may impact the survival and/or distribution of this whale.

Similar Species

There are no similar species. 

Text Sources: Thomas 2005 (COSEWIC Status Report).

For more information, visit the SARA Registry Website at www.SARAregistry.gc.ca.