Balaenoptera acutorostrata

Lacepède, 1804 - Minke whale

Distinctive Characteristics

Minke whales are generally easy to distinguish from the larger rorquals. The head is extremely pointed, viewed both from the side and from above, and the median head ridge is prominent. The dorsal fin is tall, recurved, and located about two-thirds of the way back from the snout tip. There are 30 to 70 moderately short ventral pleats (often extending just past the flippers) and 231 to 360 pairs of white to greyish baleen plates.

The minke's coloration is distinctive: dark grey dorsally and white beneath, with streaks or lobes of intermediate shades on the sides or both. Some of the streaks may extend onto the back behind the head. The most distinctive light marking is a brilliant white band across each flipper of Northern Hemisphere and some Southern Hemisphere minke whales (the band is not usually present on Antarctic animals). This band is generally visible through the water when animals are near the surface. The blow tends to be diffuse and is often not visible at all.

Can be confused with

When seen clearly, minkes are probably the easiest to distinguish of the whales of the genus Balaenoptera, by their small size, usual absence of a visible blow, unique head shape, and distinctive colour patterns (especially the flipper bands). Sei and Bryde's whales, and some beaked whales, may present identification problems, but generally only if the animals are seen at a distance.

Size

Adult minke whales reach just over 9 m in length (rarely some females may reach a maximum of 10.7 m). Maximum body weight is about 14 t. Length at birth is 2.4 to 2.8 m.

Geographical Distribution

Minke whales are widely distributed from the tropics to the ice edges in both hemispheres. Although they can be seen offshore as well, minkes are more often seen in coastal and inshore areas. Minke whales are very rare in some tropical pelagic areas, such as the eastern tropical Pacific.

Biology and Behaviour

Minke whales sometimes aggregate for feeding in coastal and inshore areas of cold temperate to polar seas. Although groups elsewhere are generally much smaller (singles, pairs, and trios), aggregations in the Antarctic may contain hundreds of animals. Minkes do not fluke-up on a dive, but they do sometimes breach and perform other aerial behaviours.

Calving occurs in low latitude areas (although the migrations of minkes are not as well-defined as those of larger rorquals) in winter months.

The prey types of minke whales are primarily krill and small schooling fishes.

Exploitation

For the last 2 decades, the minke whale has been the main target of the Antarctic whaling fleets. Although the IWC commercial whaling moratorium has afforded all great whales protection, a certain amount of “scientific whaling” continues and Norway recently resumed commercial whaling for this species. Japan also took some during recent Antarctic whaling seasons. The minke whale is the most abundant of all baleen whales.

IUCN Status

Insufficently known.

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