Northern hemisphere minke whale  (Balaenoptera acutorostrata)

The smallest of the rorqual whales, the Minke whale is also the most abundant (1). Two species are now recognised, the northern hemisphere minke whale (the subject of this species page) and the southern hemisphere minke whale (Balaenoptera bonaerensis) (2). Minke whales are slim in shape (1), with a pointed 'dolphin-like' head (4), bearing a double blow-hole (2). The smooth skin (2) is dark grey above, the belly and undersides of the flippers are white, and there is often a white band on the flipper (3). When seen at close quarters, minke whales have variable 'smoky' patterns which have been used to photo-identify individuals (1).

Occurs in all oceans of the northern hemisphere from polar waters to tropical regions. The northern hemisphere minke whale is the whale most likely to be seen from the coasts of the UK and Ireland, particularly from Scotland, western Ireland and the Northern Isles (5). In the English Channel and southern parts of the Northern Sea it is rare (5).

Inhabits inshore to offshore waters (1) and is usually more concentrated in higher latitudes during the summer and lower latitudes during the winter, but migrations vary from year to year. This whale often enters estuaries, bays and inlets, and during summer may feed around headlands and small islands (7).

Minke whales feed on fish and various invertebrates; like all baleen whales they filter their food from the water using their baleen plates like sieves (1). Although largely a solitary species, when feeding minke whales can often be seen in pairs, and on particularly good feeding grounds up to a hundred individuals may congregate (1). A number of feeding techniques have been observed, including trapping shoals of fish against the surface of the water (5). After a 10-month gestation period, births occur in mid-winter (4), at birth the calf measures up to 2.8m in length (2). It will be weaned at 4 months of age (4), and will stay with its mother for up to two years, becoming sexually mature at seven years of age (5). Minke whales have an average life span of around 50 years (5).Minke whales are fairly inquisitive and often swim by the side of boats for up to half an hour (2).

The common name of this species indicates the main threat that has faced it for many years; Minke was an 18th century Norwegian whaler who hunted small whales, flouting the whaling rules of the day (5). Despite the world moratorium on commercial whaling set up by the International Whaling Commission (IWC) in 1982, minke whales are still hunted by Norway and Japan (1). Norway officially objected to the moratorium, and Japan kills whales for 'scientific research', but the carcasses are commercially processed after the research has been carried out (1). Other potential threats facing minke whales, and indeed all cetacea, include pollution and reduction in prey abundance, perhaps as a result of over-fishing (5). Entanglement in fishing nets and the effects of long-term climate change are also likely to pose problems, but as yet the importance of these threats is unknown (5).

This whale is a UK Biodiversity Action Plan priority species. Under Schedule 8 of the Wildlife and Countryside Act of 1981, this species is fully protected in UK waters. CITES (the Convention on International Trade in Endangered Species) controls exports of whale meat and products (5). In 1996, 6 tonnes of Norwegian whale meat was confiscated by customs officials in Japan. The shipment was disguised as mackerel (1). The current population figures for northern hemisphere minke whales are unknown and highly disputed. The future status of this inquisitive whale is unclear.

For more on this species see the WDCS (Whale and Dolphin Conservation Society) Species Guide, available on-line at:
http://www.wdcs.org/dan/publishing.nsf/allweb/494E7E35C71C8D1C802568F8004C2059 For more on whales and dolphins and their conservation see the WDCS homepage at;
http://www.wdcs.org/

Information authenticated by WDCS, the Whale and Dolphin Conservation Society:
http://www.wdcs.org