Northern minke whale
The Common minke whale (Balaenoptera acutorostrata) is a small member of the suborder of baleen whales. It is the smallest species of the rorquals and the second smallest species of baleen whale. American whalemen in the 19th century simply thought of Common minke whales as "young finbacks" or a "Finback's calf", apparently under the impression that they were juveniles of their larger relative, the Fin whale.
Common minke whales are among the most robust members of their genus, the greatest height of their body being one-fifth their total length. They are dark gray dorsally and clean white ventrally. The lower jaw projects beyond the upper jaw and is dark gray on both sides - though, like the dwarf form, it can have a white mandible blaze at the rear corner of the right lower jaw. An indistinct light gray rostral saddle may be present, and a few individuals can have pale, thin blowhole streaks trailing from the blowholes. A thin, light gray, forward-directed chevron, called the shoulder streak, lies between the pectoral fins. Two light gray to whitish swaths, called the thorax and flank patches, join ventrally in the mid-lateral region, with the former the brighter of the two. The pectoral fins are relatively small, averaging about 73 cm (about 2.4 ft) in length (maximum: 1.38 m, or about 4.5 ft). They have a transverse, white band on their outer margins, which is the most distinguishing feature of the species. The smooth-sided flukes average about 2 m (6.6 ft) in width and can be nearly 3 m (about 9.8 ft) wide. They are light gray or white ventrally and bordered by dark gray. The baleen plates, which number about 230 to 360 pairs and average about 20 by 10 cm (7.9 by 3.9 in), are creamy white with a fine white fringe.
Common minke whales are found in all oceans and some adjoining seas. The migration patterns of these whales are poorly known. They occur in the North Atlantic, the North Pacific, and the Southern Hemisphere. Common minke whales prefer cooler regions. They occur in both coastal and offshore waters. They also often enter bays, estuaries, lagoons and fjords.
Common minke whales are usually seen singly or in small groups of 2-4 individuals; however, where food is abundant they can be seen in large aggregations. These whales are curious creatures. They often approach ships and wharfs which is not typical for whales of their family. They are also highly acrobatic. They can leap completely out of the water like dolphins. Common minke whales are fast swimmers. Some of their populations are migratory. Both southern and northern populations often spend winter in tropical waters, although at different times of the year. This happens because of seasonal differences in their homelands.
Like all baleens, Common minke whales are carnivorous. They feed on krill and some small fish. Their diet also includes pelagic crustaceans and cephalopods and varies by region, season, and year.
Little is known about the reproductive behavior of Common minke whales. Females are known to be promiscuous, suggesting that these minke whales exhibit polygynandrous (promiscuous) mating system. In the Atlantic, breeding takes place in December-May and in the Pacific, it lasts year round. Females have young every other year. Gestation period lasts 10 months after which a single calf is born. The calf is weaned after a period of 6 months. Common minke whales become reproductively mature at about 6-8 years of age for females and about 6-7 years for males.
Scientific and commercial whaling are major threats for the Common minke whale. They are cought largely for their meat. It is now one of the primary targets of the whaling industry. Minke whales are occasionally caught in fishing gear of various types, including set nets, fish pots, gillnets, trap nets, trawls, longlines, and seines. Habitat shifting and alteration are another threats to these whales.
According to IUCN, there is no overall population estimate available for the Common minke whale. However, there are estimates of its populations in the following area: North Atlantic - about 182,000 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers remain stable.
