Southern minke whale
The Antarctic minke whale or southern minke whale (Balaenoptera bonaerensis ) is a species of minke whale within the suborder of baleen whales. It is the second smallest rorqual after the common minke whale and the third smallest baleen whale. Although first scientifically described in the mid-19th century, it was not recognized as a distinct species until the 1990s. Once ignored by the whaling industry due to its small size and low oil yield, the Antarctic minke was able to avoid the fate of other baleen whales and maintained a large population into the 21st century, numbering in the hundreds of thousands. Surviving to become the most abundant baleen whale in the world, it is now one of the mainstays of the industry alongside its cosmopolitan counterpart the common minke. It is primarily restricted to the Southern Hemisphere (although vagrants have been reported in the North Atlantic) and feeds mainly on euphausiids.
Antarctic minke whales are among the smallest and most common of the rorqual whales, the largest number of baleen whales. These whales are noticeably more streamlined than other types of whales, being long and slender. An Antarctic minke whale has a pointed snout which is distinctively narrow, triangular, and pointed (thus the nicknames "little piked whale" and "sharp-headed finner") and a pair of blowholes; the upper part of its head is flat and broad). The upperparts of the whale are dark gray, while its underbelly is white, the flippers are pale and there are pale streaks on its sides.
The Antarctic minke whale is found in all seas in the southern hemisphere and sometimes ranges into the northern hemisphere. In summer, these animals congregate in large numbers in Antarctic waters in order to feed; during winter most of them move north to more temperate or tropical waters to mate. Antarctic minke whales do not all migrate, with some overwintering in the Antarctic. They inhabit offshore and coastal waters. During the summer, many of them are found near the ice edge, amongst pack ice or in open water surrounded by ice.
Minke whales are usually seen on their own or in pairs or threes. Bigger groups can be found in both hemispheres in high latitudes of up to 10 to 15 animals. Minke whales are known for their curiosity and so are among the most frequently observed of the rorquals (of the baleen whale family) due to their habit of approaching boats that are stationary. Their usual dive lasts 2 to 6 minutes, then they spend 1 minute up at the surface, when they blow 5 to 8 times. A minke whale breaches more frequently than other baleens, lifting at least 40% of its body out of the water and then slamming back down into the sea, making a large splash and a thudding sound. Antarctic minke whales will sometimes use their beaks to break ice that is several centimeters thick, in order to create breathing holes. Holes are usually 200 - 300 m apart.
Like all baleens, minkes are carnivorous, and are seasonal feeders. They filter out krill, small plankton, and small fish, and sometimes chase schools of sardines, cod, anchovies, herring, and capelin.
Antarctic minke whales have a polygynous mating system, one male mating with multiple females. The mating and calving usually occurs during the winter. After a gestation lasting 10-11 months, a single calf is born. Like all mammals, minke calves drink their mother's milk until they are weaned, at about 4-6 months. They remain with their mothers for up to two years. Antarctic minke whales are sexually mature at about 7-8 years old.
Scientific and commercial whaling are major threats for the Antarctic minke whale, and it is now a main target of the whaling industry in Japan, especially as larger species of whale have been depleted through hunting. Antarctic minke whales, like all cetaceans, are also vulnerable to noise and chemical pollution. Climate change is another possible major threat. With rising temperatures, the reduction of sea ice suggests a loss of 5 - 30 percent over the next 40 years of ice-associated habitat, which may also affect Antarctic krill abundance. There will be increased competition for food and space as the extent of prey populations and suitable habitat reduces, with the result that this whale population will decrease.
According to the International Whaling Commission's most recent estimate in 2003-2004, the population size of Antarctic minke whales is around 515,000 individuals. Currently this species is classified as Data Deficient (DD) on the IUCN Red List.
