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Balaenoptera acutorostratacommon minke whale

By Bridget Fahey

Geographic Range

Minke whales have a worldwide distribution, appearing in all oceans and some adjoining seas. Cooler regions seem to be preferred over tropical regions.

Habitat

Although not considered "coastal", these baleen whales rarely venture farther than 169 km from land. They also commonly enter estuaries, bays, fjords, and lagoons. They are also know to move farther into polar ice fields than other rorqual species.

Physical Description

Minkes are the smallest of the finback whales, growing to a maximum of 10.2 meters long. Females are larger than males, occasionally growing to a maximum of 10,000 kg. Coloration is dark above with a white underbelly. The head is pointed and bulletlike, with a relatively small rostrum. Baleen plates number around 300, are yellowish in color, and occasionally assymetrical in pattern. There are between 50-70 ventral grooves. A broad white band trims the dorsal side of flippers. The tail extends into two long tips. The dorsal fin is high and curved back.

  • Range mass
    6000 to 9000 kg
    13215.86 to 19823.79 lb

Reproduction

Only one young is born at a time. Gestation lasts for 10 to 11 months. Weight at birth is 450 kg. The young are weaned at 5 months, but they do not become sexually mature for 6 years. Females are thought to have young every other year. The breeding period is long--from December to May in the Atlantic and year round in the Pacific. Peak months for births are December and June. Growth stops at about 18 years for females and 20 years for males.

  • Breeding interval
    Females are thought to have young every other year.
  • Breeding season
    The breeding period lasts from December to May in the Atlantic and year round in the Pacific
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    10 to 11 months
  • Average age at sexual or reproductive maturity (female)
    6 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    2740 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    6 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    2740 days
    AnAge

Lifespan/Longevity

Behavior

Minke whales travel either singly or in small groups (2-4), although they can be found in large aggregations in the hundreds where krill is abundant. They are thought to be curious, approaching ships and wharfs which is not typical of its family. They are also highly acrobatic, able to leap completely out of the water like a dolphin. Minkes are fast swimmers. Some populations are migratory--both southern and northern populations often spend winter in tropical waters, although these are actually at different times of year as a result of seasonal differences in their homelands.

Communication and Perception

Food Habits

A baleen whale, this species feeds primarily on krill and some small fish. There are regional differences in the diet. Minkes eat krill almost exclusively in the Antarctic, but they are more omnivorous in the northern hemisphere, taking as food squid and small vertebrates such as cod, herring, and sardines.

  • Primary Diet
  • carnivore
    • eats non-insect arthropods
  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Economic Importance for Humans: Positive

Minke whales have been hunted by people for products such as meat, oil, and baleen since the Middle Ages. Regardless, it has never been of large commercial importance until other whale species were overhunted. Annual kill peaked in 1976 with 12,398 individuals, but now is down to < 1,000. These are taken primarily by indigenous peoples for food, or by scientists for research.

Economic Importance for Humans: Negative

None.

Conservation Status

The global population is estimated at over 300,000 individuals, and there seems to be no cause for concern, since this species is not commonly hunted anymore. Many populations are on appendix 1 of CITES. Numbers have also been on the rise since the early 1900's because close competitors (other rorqual species) have been overhunted.

Other Comments

A second form of minke whale called the dwarf minke has been found off Australia/ New Zealand/ South Africa. There is debate as to whether this is a subspecies of B. acutorostrata or a different species altogether.

Contributors

Bridget Fahey (author), University of Michigan-Ann Arbor.

Glossary

Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Nowak, R.M. Walker's Mammals of the World, 5th Edition. Johns Hopkins University Press.

Grizemek's Encyclopedia of Mammals. McGraw-Hill Publishing Co.

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