Whaling nations treat all minke whales as a single species, but it has now been shown that there are at least two different species, which are further divided into separate biological populations. The two recognised species are the Antarctic minke and the common minke, of which the dwarf minke is a subspecies. The dwarf minke is similar in appearance to the common minke, but is only found in the Southern Hemisphere and as the name suggests, it is smaller. The common minke whale is the main species targeted by Japan in the North Pacific and Norway and Iceland in the North Atlantic when they undertake 'scientific' and/or commercial whaling.
Minke whales are the smallest and most abundant of the rorqual whales. They have a sharply pointed snout, straight mouthline and a long ridge along the head with two blowholes. They have hundreds of baleen plates 20 to 30cm long growing from their upper jaws and between 50 and 70 pleats running from their throat and ending just past their flippers. These pleats stretch, allowing the whale to take in huge volumes of water when feeding. Minke whales have a streamlined shape and smooth skin with no callosities or barnacles. They are black, dark brown, or grey on their upper side with a lighter belly and a dorsal fin positioned far behind the centre of their back. Minke whales in the northern hemisphere have a white band on each flipper, though many in the southern hemisphere do not. The fluke of a minke whale is rarely seen above the surface.
Minke whales appear to be mainly solitary, although recent research on dwarf minke whales in the Great Barrier Reef reveal they are more social and communicative than previously believed. They are relatively fast swimmers, occasionally spy-hopping and breaching. When they surface to breathe, their snout appears first. These whales can stay under water for as long as 20 minutes. They are unlikely to bow-ride, but they will swim beside a vessel for some distance and can be seen sometimes at the surface feeding beneath flocks of seabirds. Dwarf minke whales are active and highly manoeuvrable, with an inquisitive nature - they often approach boats - and can swim at 12 knots for short bursts. As with the common minke, most sightings are of a single whale or a pair, but groups of over 20 whales may occur around a boat during a single encounter. They are regularly seen breaching.
Common minke whales and are found in oceans all over the world. They prefer cooler temperatures, are frequently seen in coastal and inshore waters and are less common in tropical waters. During the winter they typically travel toward warmer waters and in summer move closer to the poles. Some populations of minke whales stay in the same area all year round. Sightings suggest that dwarf minke whales have a more coastal distribution than Antarctic minke whales. They are widespread and may have a complex population structure. They have been recorded off South Africa, Australia, New Zealand, New Caledonia, and the eastern coast of South America during March to December. There are scattered records from the sub-Antarctic during December to March. Minke whales (both common and dwarf) are threatened by commercial whaling and hunting, chemical pollution and entanglement in fishing nets. The estimated population of 209,800 is composed of; North Atlantic pop. – 174,000, West Greenland pop. – 10,800, North west Pacific and Okhotsk Sea pop. – 25,000. The common minke whale global population however is currently under review by the IWC whilst little information is available for the dwarf minke whale. The species is listed as of Least Concern by IUCN (2008).