Common minke whale

The common minke whale or northern minke whale (Balaenoptera acutorostrata) is a species of minke whale within the suborder of baleen whales.

It is the smallest species of the rorquals and the second smallest species of baleen whale. Although first ignored by whalers due to its small size and low oil yield, it began to be exploited by various countries beginning in the early 20th century. As other species declined, larger numbers of common minke whales were caught, largely for their meat. It is now one of the primary targets of the whaling industry. There is a dwarf form in the Southern Hemisphere.

This species is known in the fossil record from the Pliocene epoch to the Quaternary period (age range: 4.7 million years ago to present day).

Vernacular names

The origins of the species' common name are obscure. One of the first references to the name came in Henrik Johan Bull's account of his 1893–95 voyage to the Antarctic, when he mentioned catching a small whale "called in the Arctic language a Mencke whale, after a German who accompanied Mr. Foyn on some of his voyages."Bull, H. J. (1896). The cruise of the 'Antarctic' to the South Polar regions. London: Edward Arnold. According to the British writer John Guille Millais (The mammals of Great Britain and Ireland, 1906, vol. 3, p. 279), "Minkie was a Norwegian seaman who was always calling 'Hval' at whatever backfin he saw. He is now regarded as the type of the 'tenderfoot' at sea. Norwegians often refer to any small whale with some contempt or amusement as a 'Minkie' or 'Minkie's hval'."Allen, G. M. (1916). The whalebone whales of New England. Boston. The American marine biologist and painter Richard Ellis, citing the Norwegian scientist Age Jonsgård, stated "that Meincke was a German laborer working for Svend Foyn, inventor of the grenade harpoon. Meincke 'one day mistook a school of this whale species for blue whales.... most probably he made this mistake during Foyn's whaling operations in the Varanger Fjord between 1868 and 1885."Ellis, Richard. 1980. The Book of Whales. Alfred Knopf, New York.

It has formerly been known as the little piked whale, the lesser or least rorqual, and the sharp-headed finner. American whalemen in the 19th century simply thought of them as "young finbacks" or a "Finback's calf", apparently under the impression that they were juveniles of their larger relative, the fin whale. They were also called zwergwal (German: "dwarf whale") or vågehval (Norwegian: "bay whale"). In Japan they are called koiwashi-kujira ("little sardine whale") or minku-kujira ("minke whale").Omura, H. and H. Sakiura. (1956). "Studies on the little piked whale from the coast of Japan". Sci. Rep. Whales Res. Inst., 11: 1-37. In Greenland they are known by the Danish name sildepisker ("herring thresher").Boertman, David. (2007). "Greenland red list", p.60. Greenland Government and Aarhus University. . (retrieved 2014.5.21) In Spanish it is known as Rorcual aliblanco (Whitewing Rorcual), Ballena minke común (Common Minke whale) or Ballena enana (Dwarf whale).

Taxonomy

History

Otto Fabricius, in his Fauna Groenlandica (1780), was the first to describe the minke, noting its small size and white baleen – but he described it erroneously under the name Balaena rostrata (the taxonomic designation for the beaked whale). In 1804, Baron de Lacepede named it Balaenoptera acuto-rostrata, basing his description partly on the stranding of a juvenile female near Cherbourg, France in 1791.True, F. W. (1904). The whalebone whales of the western North Atlantic: Compared with those occurring in European waters. Washington: Smithsonian institution.

In 1872, the American whaleman and naturalist Charles Melville Scammon described and named Balaenoptera davidsoni, after an pregnant female that was found dead on the north shore of Admiralty Inlet in October 1870 in then Washington Territory (now Washington state) and towed into Port Townsend Bay by Italian fisherman, who flensed it on the beach. Scammon mentioned its "dwarfish size", "pointed head", "falcated dorsal fin", and the "white band" on its "inordinately small, pointed pectorals". In 1877, the Italian geologist and paleontologist Giovanni Capellini described and named Sibbaldius mondini from a juvenile specimen that was captured off Italy in 1771. Both were later synonymized with B. acutorostrata.

A smaller, Southern Hemisphere form of minke whale with white-banded flippers was first described in separate studies by Peter Best (1985) and Peter Arnold, Helene Marsh, and George Heinsohn (1987), though a white-flippered form in the Southern Hemisphere had been noted earlier. The former described a "diminutive form" based on specimens caught off Durban, South Africa, while the latter named a "dwarf form" based on specimens and sightings from Australia. This unnamed subspecies has a prominent white flipper and shoulder blaze and a dark throat patch, whereas what was called the "dark-shouldered" or "ordinary" form of minke whale (now known as a separate species, the Antarctic minke whale, B. bonaerensis) lacked these contrasting markings.

Until recently, all minke whales were considered a single species. However, the common minke whale was recognized as a separate species from the Antarctic minke whale based on mitochondrial DNA testing. This testing also confirmed that the Antarctic minke whale is the closest relative of the common minke whale, thus confirming the validity of the minke whale clade.

Divergence

Common and Antarctic minke whales diverged from each other in the Southern Hemisphere 4.7 million years ago, during a prolonged period of global warming in the early Pliocene which disrupted the Antarctic Circumpolar Current and created local pockets of upwelling, facilitating speciation by fragmenting populations. The radiation of common minke whales into the Northern Hemisphere occurred rapidly about 1.5 million years ago during a period of cooling in the Pleistocene.

Hybrids

There have been two confirmed hybrids between common and Antarctic minke whales. Both were caught in the northeastern North Atlantic by Norwegian whaling vessels. The first, an female taken off western Spitsbergen () on 20 June 2007, was the result of a pairing between a female Antarctic minke and a male common minke. The second, a pregnant female taken off northwestern Spitsbergen () on 1 July 2010, on the other hand, had a common minke mother and an Antarctic minke father. Her female fetus, in turn, was fathered by a North Atlantic common minke, demonstrating that back-crossing is possible between hybrids of the two species.

Description Size

The common minke whale is the smallest of the rorquals, and one of the smallest baleen whales (second smallest only to the Pygmy right whale). In the North Atlantic, Norwegian whaling vessels in 1940 allegedly caught individuals of up to in length, but they were likely only measured visually in comparison to objects of known dimensions aboard the ships themselves – the longest caught in subsequent years were typically only up to in length. In the North Pacific, Soviet vessels operating out of the Kuril Islands claimed to have caught two males of 12.2 (40 ft) and and a female of – the first two were landed in 1951, the third in 1960.Ivashin, M. (1992). "USSR catch and sightings data". Report of the Scientific Committee on North Pacific minke whales (Appendix 7), p. 168. These likely represent undersized sei whales, part of the massive misreporting of whaling data by the Soviet Union in the North Pacific and elsewhere. The maximum weight recognized by scholars is .

The longest measured by Icelandic scientists were an male and a female, while the longest caught by the Japanese in the western North Pacific were males and a female – the latter caught off eastern Hokkaido in 1977. For the dwarf form, the longest reported are a male caught in May 1973 and a 7.77 (25.5 ft) female caught in May 1970, both taken off South Africa.

Males caught in the western North Pacific and weighed whole on a truck scale averaged between 2.85 and 4.23 metric tons (3.14 and 4.66 short tons) (range: 0.86 to 6.36 metric tons, 0.95 to 7.01 short tons), while females averaged between 1.93 and 3.63 metric tons (2.13 and 4.00 short tons) (range: 0.84 to 8.35 metric tons, 0.93 to 9.20 short tons).Kishiro, T., Kato, H., Ohizumi, H., Yoshida, H., Saito, T., Isoda, T., Tabata, S., Sakakibara, M., Saino, S., Hara, T., Hayashi, T., Miyashita, T., Fukudome, K., Kiwada, H., and Kawahara, S. (2003). "Report of the 2002 JARPN II survey in the western North Pacific. Part II: Coastal component – Coastal survey off Kushiro, northeast Japan". Paper SC/55/O8 submitted to the 55th IWC Scientific Committee, 26pp.Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Ryono, T., Tabata, S., Sakakibara, M., Saino, S., Hara, T., Hayashi, T., Tomizawa, Y., Tamai, K., Okamoto, R., Fukuoka, M., Watanabe, H., Tsunekawa, M., and Kawahara, S. (2004). "Report of the coastal survey on common minke whales off Sanriku coast, northeast Japan: the Japanese whale research program under special permit in the western North Pacific–Phase II (JARPN II) in 2003 (Part II) – Coastal component". Paper SC/56/O14 submitted to the 56th IWC Scientific Committee, 31pp.Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., and Kawahara, S. (2005). "Cruise report of the coastal survey on common minke whales off Kushiro, northeast Japan: the 2004 JARPN II survey (Part II) – Coastal component". Paper SC/57/O4 submitted to the 57th IWC Scientific Committee, 37pp.Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Saito, T., Shigeo, T., Morita, Y., Sato, H., Okada, A., Tomizawa, Y., Saino, S., Kuroishi, H., Ebisui, T., Nakai, K., Nishiwaki, S., and S. Kawahara. (2006). "Cruise report of the second phase of the Japanese Whale Research Program under Special Permit in the western North Pacific (JARPN II) in 2005 – Coastal component off Sanriku". Paper SC/58/09 Submitted to the 58th IWC Scientific Committee, 30 pp.Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., and Kawahara, S. (2006). "Cruise report of the Second phase of the Japanese Whale Research Program under Special Permit in the western North Pacific (JARPN II) in 2005 – Coastal component off Kushiro". Paper SC/58/O10 submitted to the 58th IWC Scientific Committee, 32pp.Goto, M., Kato, H., Zenitani, R., Yoshida, H., Saito, T., Tabata, S., and Kawahara, S. (2007). "Cruise report of the second phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II) in 2006 – Coastal component off Sanriku". Paper SC/59/O6 submitted to the 59th IWC scientific Committee, 34pp.Yoshida, H., Kato, H., Kishiro, T., Miyashita, T., Iwasaki, T., Minamikawa, S., and Kawahara, S. (2007). "Cruise report of the second phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II) in 2006 – Coastal component off Kushiro". Paper SC/59/O7 submitted to the 59th IWC Scientific Committee, 43pp.Bando, T., Kato, H., Kishiro, T., Goto, M., Saito, T., Tabata, S., and Kawahara, S. (2008). "Cruise report of the second phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II) in 2007 – Coastal component off Sanriku". Paper SC/60/O6 submitted to the 60th IWC scientific Committee, 27pp.Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Iwasaki, T., Kanaji, Y., and Kawahara, S. (2008). "Cruise report of the Second phase of the Japanese Whale Research Program under Special Permit in the western North Pacific (JARPN II) in 2007 – Coastal component off Kushiro". Paper SC/60/O7 submitted to the 60th IWC Scientific Committee, 33pp.