Last modified: Sunday December 10th, 2000

Minke whale

Balaenoptera acutorostrata (Lacépède, 1804)

Taxonomy

The taxonomy of the minke whale is confusing. Different authors recognize different subspecies. In some cases these may just be regional variations between isolated stocks. Further genetical and morphological work is needed to resolve this. According to Rice (1998) there are 2 species of minke whale: the Northern minke whale B. acutorostrata (Lacépède, 1804), and the Antarctic minke whale B. bonaerensis (Burmeister, 1867). Furthermore, there may be at least 2 subspecies of the Northern minke whale: the North Atlantic form B. a. acutorostrata and the North Pacific form B. a. scammoni.

Appearance

The minke whale is the smallest of the rorqual whales, seldom exceeding 10 m in length. In Korean waters, the minke whales are usually between 5.8 and 6.5 m and weigh 2-2.7 metric tonnes.

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. There are regional variations in the body and baleen plate coloration. Generally, minke whales are black, grey or brown dorsally and light ventrally. In the Northern hemisphere, the minke whale has an obvious white stripe on the flippers. In the Southern hemisphere there is a lot of variation in flipper striping (often the stripe is completely absent).

Distribution

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.

Population dynamics and life history

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. The age at sexual maturity is unknown. In the North Atlantic, gestation is also about 10 month. Females may give birth every 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.

There is more detailed information available on the Southern hemisphere minke whales. There, the calving cycle is about 14 months. Usually there is one calf, but twins and even triplets have been reported. Females become sexually mature at 7.9 m (6-8 years of age), males at 7.3 m (5-8 m). Pregnancy rates have been reported from 0.78 to as high as 0.96, although the latter figure could be biased because of segregation of pregnant and nonpregnant females. The maximum longevity is probably between 33 and 50 years.

Population status

The minke whale is considered to be reasonable abundant. However, the exact sizes of the various stocks are subject of discussion. The following stocks estimates are available:

Exploitation

In the North Pacific, minke whales were caught by the Russian and Japanese whaling fleets since the 1930s. The Japanese took about 400 whales per year. When the Republic of Korea joined the IWC, there has been a steady catch of 500-1000 whales per year in Korean waters.

In the North Atlantic, minke whales have been hunted since the middle ages, when the whales were caught in nets. Modern whaling for minke whales started in the 1920s. Between the 1920s and 1973, the Norwegian fleet has taken about 94,000 minke whales in this area. In the 1980s a quota of about 2,500 whales was set for the North Atlantic.

In the Southern hemisphere, the first minkes were caught in 1894-1895. Commercial whaling for minkes in this region started in the 1950s and increased after the decline of other whale stocks. Between 1972 and 1980, the Japanese fleet took over 30,000 whales in this region.

Since the moratorium on commercial whaling that took effect in the 1985-1986 season, minke whales have been taken in small numbers under scientific permits. In 1996, the Norway started its commercial hunt for minke whales again. In 1996, 113 minkes were caught. In the 1997 season, 503 whales were caught (a bit short of the self-imposed quota of 580 whales) and in 1998, 624 whales were caught (quota: 671). For more on Norwegian whaling, see the High North Alliance Web site. Greenland has been assigned a quota of 465 minke whales for the period 1995-1997 under the IWC Aboriginal Whaling regulations.

Feeding

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.

References

Stewart, B.S. and S. Leatherwood (1985)
Minke whale. In: S.H. Ridgway and R.J. Harrison (eds.): Handbook of Marine Mammals, Vol. 3: The Sirenians and Baleen Whales. pp.91-136. Academic Press.
Klinowska, M. (1991)
Dolphins, Porpoises and Whales of the World. The IUCN Red Data Book. IUCN, Gland, Switzerland.
Rice, D.W. (1998)
Marine mammals of the world - Systematics and distribution
Society of Marine Mammalogy Special Publication Number 4, 231 pp.


Note on the pictures

The pictures were taken in July 1998 in Iceland, on a whale watching tour on Skjálfandi, out of Húsavík, in Northern Iceland. The tour was organized by North Sailing

For more minke whale pictures and additional information, visit the Minke Whales - Dwarf Minke Whale pages.


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