Bowhead Whale (Balaena mysticetus)

                 

Class: Mammalia
Order: Cetacea
Family:    Balaenidae
Size:    Length: Up to 60 feet (18 m)
Weight: Up to 120,000 pounds (54,431 kg)   
Diet: Plankton
Distribution: Arctic waters, sub-Arctic waters of the north Atlantic and Pacific Oceans
Young:  1 calf every 3 to 4 years
Animal Predators:  Killer whales
IUCN Status: Lower Risk, Conservation Dependent
Terms: Group: Pod   Young: Calf
Lifespan: Up to 185 years

 

Facts/Trivia:

·         Bowheads are also known as Greenland right whales, Arctic whales, or Great polar whales.  

·         Before commercial whaling, there were over 50,000 bowhead whales worldwide.

·         Unlike many other whales, bowheads have smooth skin that is nearly free of external parasites.

·         They are the second largest whales in the world—only blue whales are larger.

·         Bowheads can filter copepods—a type of crustacean—at a rate of 50,000 per minute.

 

Description

Bowheads have extremely thick blubber (up to 28 inches/70 cm thick) because they spend their entire lives in the cold polar waters of the extreme north. Their skin is black with a white patch on the underside of their triangular head. They have two blowholes located at the top of their head. They have no dorsal fins, and short, narrow flippers. Bowheads are baleen whales, which means that instead of teeth, they have a row of plates in their mouth known as baleen that they use to filter their food. Baleen is made of keratin, a flexible material also found in fingernails and hooves that becomes frayed at the tips. Also called whalebone, it was used in previous centuries to make corset stays and umbrella ribs. In bowheads, the baleen plates are extremely long and dark, usually dark grey or black. Bowheads are extremely vocal whales, and have the largest mouth and head of the entire animal kingdom—about one-third the length of their body. The name bowhead comes from the resemblance of their mouth to an archers bow. The lower jaw makes a U-shape around the upper jaw, resulting in a crown at the top of the head, and is usually marked with white spots, contrasting with the rest of the whales black body. Bowhead females tend to be larger than their male counterparts.

 

Habitat

Bowhead populations are restricted to the northern waters of the Atlantic, Pacific and Arctic oceans, near ice floes. 

 

Feeding Habits

To feed, bowheads opens their mouths while swimming, then close them around a concentration of plankton and the water surrounding it. They then strain the water out through the bristly baleen plates on the upper jaws, leaving behind only the food. Bowheads are extremely strong whales that can break holes through ice up to 12 inches (30 cm) thick.

 

Reproduction

Mating occurs during late winter and early spring. Spring migration takes place soon after this and the female gives birth between April and June, with most births occuring in May. Bowheads give birth in the frigid waters of the north, after a 13 to 14 month pregnancy. Calves immediately begin swimming at birth. Newborns are 11 to 18 feet (3.5 to 5.5 m) long and weigh approximately 2,000 pounds (907 kg), and during their first year grow to about 26 feet (7.9 m) in length. The calf is fed with its mother’s milk until it is weaned, which occurs between nine and 15 months after birth. Bowheads do not begin to reproduce until they are 10 to 15 years of age. 

 

Behaviour

Bowhead whales spend their time in small pods of up to six individuals, but may congregate in larger pods of up to 50 whales in the spring and fall when they migrate. They sometimes travel in a V-shape formation, swimming at the same speed to filter feed together. True cold water whales, they only migrate as far south as the Bering and Labrador seas. They are slow swimmers and non-aggressive, and will dive and retreat under the ice when threatened. Bowhead whales are able to smash through ice that is one to two feet (30.5 to 61 cm) thick to breathe. They are highly vocal, using their songs, calls and the echoes of their songs to attract mates and navigate through icy waters. 

 

Conservation

Bowhead whales are listed as endangered under the Endangered Species Act of 1973 (ESA) and depleted under the Marine Mammal Protection Act of 1972 (MMPA). During the 17th century, when commercial whaling began in earnest, bowheads were hunted for their blubber, meat, oil, bones and baleen. In the mid-1800s kerosene was invented and became a cheaper alternative to whale oil, but whaling continued until the bowhead population had been reduced by 90 percent. In 1935, the bowhead was granted worldwide protection by the International Convention for the Regulation of Whaling. Bowheads can now only be legally hunted off the coast of Alaska by native peoples. The bowhead population is slowly recovering in most areas where they live and is estimated at approximately 8,000 individuals. Whaling in Canadian waters is prohibited by The Canadian Whaling Regulations. Although bowhead whales are listed as Lower Risk, Conservation Dependent on the IUCN Red List, several subspecies have their own special ratings. The Baffin Bay, Davis Strait stock and the Okhotsk Sea subpopulation are listed as Endangered; the Hudson Bay, Foxe Basin stock listed as Vulnerable; and the Svalbard-Barents Sea Stock is listed as Critically Endangered. 

 

Sources

All the World’s Animals: Sea Mammals, Torstar Books Inc. 1984

http://www.enchantedlearning.com/subjects/whales/species/Bowheadwhale.shtml

http://animaldiversity.ummz.umich.edu/accounts/balaena/b._mysticetus$narrative.html

http://www.nature.ca/notebooks/english/bowhead.htm

http://www.acsonline.org/factpack/bowhead.htm

http://www.state.ak.us/local/akpages/FISH.GAME/notebook/marine/bowhead.htm

http://whales.magna.com.au/DISCOVER/BOWHEAD/bowg.html

http://collections.ic.gc.ca/arctic/species/bowhead.htm

http://nmml.afsc.noaa.gov/education/cetaceans/bowhead2.htm

http://www.cetacea.org/bowhead.htm

http://www.redlist.org