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Bowhead Whale (Balaena mysticetus)

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Bowhead whales are mysticetes, which means they have “baleen” plates instead of teeth for filtering food out of the ocean. Bowhead whales have extremely long baleen plates (up to 14 feet (4.25 m)) and feed almost exclusively on zooplankton, which includes small to moderately sized crustaceans such as copepods, euphausiids, and mysids, as well as other invertebrates and fish. Bowhead whales have a dark body and a distinctive white chin. Unlike most cetaceans, they lack a dorsal fin.

The bowhead whale has a massive bow-shaped skull that is over 16.5 feet (5 m) long and about 30-40% of their total body length. This large skull allows the bowhead whale to break through thick ice with its head. The bowhead whale also has a 17-19 inch (43-50 cm) thick blubber layer, thicker than any other whale’s blubber.

Bowhead whales reach sexual maturity at about the age of 20 years, when they reach a length of about 35-40 ft (13-14 m). Females generally have one calf every 3 to 4 years after a gestation period around 13 to 14 months. Calves are usually about 13 ft (4 m) long at birth and weigh about 2,000 lbs (900 kg). Adults grow to about 45-60 ft long (14-18 m) and weigh 150,000- 200,000 lbs (75-100 tons). The average and maximum lifespan are unknown; however, some evidence suggests that they can live over 100 years.

This species is classified as LEAST CONCERN according to the IUCN's Red List.
This species is classified as LEAST CONCERN according to the IUCN’s Red List.

Status

ESA Endangered – throughout its range
MMPA Depleted– throughout its range
CITES Appendix I – throughout its range

Species Description

Weight:
150,000-200,000 lbs (75-100 tons) for adults;
at birth, about 2,000 lbs (900 kg)
Length:
about 45-60 ft (14-18 m) for adults;
at birth, about 13 ft (4 m) long
Appearance:
dark body with a distinctive white chin, and–unlike most cetaceans–they do not have a dorsal fin; the bow-shaped skull is over 16.5 feet (5 m) long, about 35% of their total body length
Lifespan:
unknown, but some evidence suggests that they can live over 100 years;
they reach sexual maturity around 20 years old
Diet:
zooplankton (crustaceans like copepods, euphausiids, and mysids), other invertebrates, and fish
Behavior:
they use their large skull to break through thick ice

RELATIVE SPECIES: North Atlantic and North Pacific Right Whales

OTHER NAMES: Greenland Right Whale

NEIGHBORING SPECIES: Gray Whale, Northern Bottlenose whale, Beluga, Narwhal, Killer Whales

PREDATORS: Humans

THREATS: Whaling by indigenous peoples for fuel, fishing gear, ship strikes, noise and pollution from oil drilling.

DIET: Krill, copepods and various invertebrates.

MANNER OF FEEDING: Skim feeding.

BEHAVIOR: Breaching and lobtailing. Occasionally swim together but are usually solitary. They often break through ice with their large powerful heads. The sounds they make are believed to be a form of primitive echolocation. Migration depends on ice formation.

REPRODUCTION: Give birth every 3-4 years. Gestation is 13-14 months. Calves are weaned at 9-12 months. Males have a loud mating call. Females mate with multiple males. Mating occurs in late winter.

LIFE SPAN: over 100 years.

Habitat

Bowheads live in the Arctic Ocean and adjacent seas. They spend most of the summer in relatively ice-free waters of seas adjacent to the Arctic Ocean. They are associated with sea ice the rest of the year.

Distribution

Bowhead whales are circumpolar, ranging throughout high latitudes in the Northern Hemisphere. They spend the winter associated with the southern limit of the pack ice and move north as the sea ice breaks up and recedes during spring. Five stocks of bowhead whales have been recognized. Three of these stocks occur in the North Atlantic: the Spitsbergen, Baffin Bay-Davis Straight, and Hudson Bay-Fox Basin stocks; and two in the North Pacific: the Sea of Okhotsk and Bering-Chukchi-Beaufort stocks

Population Trends

The historic worldwide abundance of bowhead whales prior to commercial exploitation is estimated at about 30,000-50,000. Commercial exploitation drove the worldwide abundance down to about 3,000 by the 1920s. Current abundance is estimated between 7,000 and 10,000 animals.

The most recent stock assessment report with current population estimates are available on our website.

Bowhead whales have been hunted by indigenous peoples for food and fuel for the last 2,000 years. However, subsistence harvest is currently regulated by quotas set by the International Whaling Commission  and are allocated and enforced by the Alaska Eskimo Whaling Commission. Bowhead whales are harvested by Alaskan Natives in the Beaufort, Bering, and Chukchi Seas. The number of subsistence whaling crews in Alaska increased from 44 to 100 between 1970 and 1977. During this same period, the average number of whales landed increased from 15 per year to 30 per year, and the percentage of whales struck but lost also increased, possibly reflecting an increase in inexperienced crews. The annual level of subsistence landings averaged 37 whales per year from 1990-2000.

Threats

Historically:

  • commercial harvest
    • targeted by hunters because they are slow and big, with large amounts of blubber
    • pursued by European and American commercial whalers for lamp oil and baleen
    • North Atlantic stocks were hunted commercially for almost four hundred years, beginning in the 15th or 16th century
    • Commercial hunting of bowheads in the North Pacific started when they were discovered there in the 1840s
      NOTE: Commercial whaling of bowheads effectively ended by 1921, when the worldwide population of the species declined to about 3,000. Moratoriums on commercial whaling went into place later and are still in effect today.

Currently:

  • ship strikes
  • entanglement in fishing gear
  • contaminants
  • anthropogenic noise, especially from offshore oil drilling

Conservation Efforts

Since ending commercial exploitation of bowhead whales, conservation efforts have been focusing on monitoring stocks, determining population structure, identifying calf-rearing habitat, and studying feeding ecology.

All five stocks are listed on the IUCN Red List This link is an external site.. The Spitsbergen, Baffin Bay-Davis Strait, and the Sea of Okhotsk stocks are listed as “endangered.” The Hudson Bay-Fox Basin stock is listed as “vulnerable” and the Bering-Chukni-Beaufort stock is listed as “lower risk, conservation dependent.”

Subsistence harvest is currently regulated by quotas set by the International Whaling Commission This link is an external site. and are allocated and enforced by the Alaska Eskimo Whaling Commission.

Regulatory Overview

Prior to the Endangered Species Act (ESA) of 1973, bowhead whales were protected at different times under the 1931 League of Nations Convention, the Endangered Species Preservation Act (ESPA) of 1966, and the Endangered Species Conservation Act (ESCA) of 1969. The ESCA ended commercial whaling in the United States. Bowhead whales are also listed in Appendix 1 of the Convention on International Trade in Endangered Species of 1973 (CITES) This link is an external site., which prohibits trade of the species. Bowhead whales also receive additional protection under the Marine Mammal Protection Act (MMPA) of 1972.

The International Whaling Commission (IWC), established in 1946 by the International Convention for the Regulation of Whaling, continued a prohibition on commercial whaling that was initiated with the 1931 League of Nations Convention. The IWC began to regulate commercial whaling among signatory nations in 1964. In 1972, the IWC asked the United States to gather data on aboriginal subsistence whaling. The IWC subsequently called for a ban on subsistence bowhead whaling in 1977, based on increasing concerns about the status of bowhead whale populations and documentation of increases in subsistence whaling in Alaska and loss of struck whales. The United States requested modification of the ban and the IWC responded with a limited quota. Currently, subsistence harvest is limited to nine Alaskan villages.

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Balaenidae
Genus: Balaena
Species: mysticetus

References:

  • NOAA
  • knopf, Alfred A. Guide to Marine Mammals of the World.Random House. 2002
  • http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/bowheadwhale.htm

Cool/Gross/Weird:

  • Of all large whales, the bowhead whale is the most adapted to life in icy cold water. It has a layer of blubber up to 1.6 feet (50 cm) thick.
  • The bowhead whale has a huge head that it uses to break through thick ice.  Can break through ice 6ft thick.
  • No dorsal fin.
  • Most adapted out of any whale to live in cold water.
  • They hold their breath for a long time so they can swim under ice.
  • Most are identified from scars they acquire from breaking through ice.
  • They may be the oldest living mammal in the world.

-TSF-

 

 
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