Minke Whale
Scientific Name: Balaenoptera bonaerensis (Antarctic) Balaenoptera acutorostrata (Northern Whale)
The Minke Whale (pronounced Mink-ey) is the second smallest of the baleen (filter feeding) whales, the smallest being the Pygmy Right Whale. They belong to the rorqual family of whales (those whales with baleen, dorsal fins, and throat pleats). Male and female Minke Whales measure an average of 6.9 and 7.4 meters in length, respectively, at sexual maturity (6-8 years of age). Estimates of maximum length vary from 9.1m to 10.7m for females and 8.8m to 9.8m for males. Both sexes typically weigh 4-5 tonnes at maturity, and the maximum weight may be as much as 14 tonnes.
Minke Whales are distinguished from other whales by a white band on each flipper. The fin and back are usually black or dark-grey above and porcelain white underneath. The body of a minke whale is slender and very streamlined; the head is narrow and pointed. In the Northern hemisphere, the minke whale has an obvious white stripe on the flipper, however In the Southern hemisphere there is a lot of variation in flipper striping (often the stripe is completely absent). The rostrum is very narrow and pointed, with a single ridge from the blowholes to the rostrum. The dorsal fin is relatively tall and sickle-shaped and positioned about 2/3 down the length of the body.
The whales breathe 3-5 times at short intervals before 'deep-diving' for 2-20 minutes. Deep dives are preceded by a pronounced arching of the back. The maximum swimming speed of minkes has been estimated at 20-30km/h. Minke Whales have between 240 and 360 baleen plates on each side of their mouths. Minke Whales typically live for 30-50 years; in some cases they may live for up to 60 years.
These whales appear to be more solitary than other baleens and are usually seen singly or in pairs, although larger groups can gather. Some individuals have been closely monitored and remain within certain areas or "home ranges". Females tend to stay near the shores while males will be found further out to sea. Killer whales have been known to feed on the minke.
Encounters
The total population of Minke Whales is estimated to be in the order of 184,000 (95% confidence interval, IWC Scientific Committee 2004) in the Central and North East Atlantic. As of 2005, there are no agreed estimates for North Pacific or Southern Hemisphere. The IWC IDCR/SOWER population surveys (1978/79-2003/04) will give a revised estimate to the IWC scientific committee at the annual IWC meeting in 2006. Minke Whales are widely distributed throughout the world, commonly found from the poles to the tropics but prefer the open sea. The minke whale is widespread and seasonally abundant in the North Atlantic. In summer they migrate north. There may be segregation of the sexes in summer. They range from Florida to Labrador and Greenland and from North Africa to north of Spitsbergen. In the Pacific they range from the tropics (Vietnam, Baja California) to the Bering Sea. In the Southern hemisphere they have a circumpolar distribution between the Antarctic and as far North as Surinam and Madagascar.
On account of their relative abundance Minke Whales are often the focus of whale watching cruises. Minke Whales are frequently inquisitive and will indulge in 'human-watching'. In contrast to the spectacularly acrobatic Humpback Whale, minkes do not raise their fluke out of the water when diving and are less likely to breach (jump clear of the sea surface). This, combined with the fact that minkes can dive under water for as long as twenty minutes, has led some whale-watching enthusiasts to label them 'stinky minkes'. The name may also be applied because it is frequently possible to smell the breath of a Minke Whale whilst observing it from a boat.
Diet
In the North Pacific, the minke whale feeds on euphausiids (krill) and sand lance. In the North Atlantic the minke whale is known to feed on sand lance, sand eel, krill, salmon, capelin, mackerel, cod, herring and a number of other fish species. In the Antarctic they feed predominantly on krill.
Reproduction
In the Pacific, the gestation period is about 10 months. At birth, the calves are 2.4-2.7 m long. Females become sexually mature at 7.3 m and males at 6.7-7.0 m in length. In the North Atlantic, gestation is also about 10 month. Females may give birth every year, or every other year. Lactation lasts 4-5 months. In the Atlantic the age at sexual maturity has been estimates at 7.1 years in females and 6 years in males.
Conservation
Whaling was mentioned in Norwegian written sources as early as the year 800 and hunting Minke Whales with harpoons was common in the 11th century. In Western Norway, Minkes were trapped in bays and coves and killed with the help of bacteria infected arrows, a form of whaling that continued up until the 20th century.
By the end of the 1930s they were the target of coastal whaling from countries including Brazil, Canada, China, Greenland, Japan, Korea, Norway, and South Africa. Minke Whales were not then regularly hunted by the large-scale whaling operations in the Southern Ocean on account of their relatively small size. However, by the early 1970s, following the over-hunting of larger whales such as the Sei, Fin, and Blue Whales, Minkes attracted the attention of these whalers too. By 1979 the Minke was the only whale caught by Southern Ocean fleets. Hunting continued apace until the general moratorium on whaling was introduced in 1986. According to a study by the International Whaling Commission, 116,568 Minke Whales were caught by whalers between 1904 and 2000. Around 100,000 of these were killed in the Southern Ocean.
Following the moratorium, most hunting of Minke Whales ceased. Japan and more recently Iceland (in August 2003) have continued hunting for Minkes on scientific grounds, however, these "scientific grounds" are criticized by many organizations as being a cover for commercial whaling. Both Iceland and Japan have the long term goal of resuming open commercial whaling. Although Norway initially followed the moratorium, they placed an objection to it with the IWC and resumed a commercial hunt in 1993. Norwegian whalers caught 639 in 2005. The quota for 2006 was set at 1052 animals, from which a catch of 521 was taken.
Like other cetaceans, minke whales are also threatened by degradation of their habitat. This may be caused by depletion of their prey, perhaps resulting from over-fishing, and pollution and global climatic changes. Climatic change could, for example, affect ocean currents and therefore the locality and abundance of the whales' prey. An unknown number of minke whales also become entangled in fishing nets each year.
