Minke whale
The minke whale (/ˈmɪnki/), or lesser rorqual, is a species complex of baleen whale.[1] The two species of minke whale are the common (or northern) minke whale and the Antarctic (or southern) minke whale.[2] The minke whale was first described by the Danish naturalist Otto Fabricius in 1780, who assumed it must be an already known species and assigned his specimen to Balaena rostrata, a name given to the northern bottlenose whale by Otto Friedrich Müller in 1776.[3] In 1804, Bernard Germain de Lacépède described a juvenile specimen of Balaenoptera acuto-rostrata.[4] The name is a partial translation of Norwegian minkehval, possibly after a Norwegian whaler named Meincke, who mistook a northern minke whale for a blue whale.[5]
Most modern classifications split the minke whale into two species:
Taxonomists further categorize the common minke whale into two or three subspecies; the North Atlantic minke whale, the North Pacific minke whale and dwarf minke whale. All minke whales are part of the rorquals, a family that includes the humpback whale, the fin whale, the Bryde's whale, the sei whale and the blue whale.
The junior synonyms for B. acutorostrata are B. davidsoni (Scammon 1872), B. minimia (Rapp, 1837), and B. rostrata (Fabricius, 1780). There is one synonym for B. bonaerensis – B. huttoni (Gray 1874).
Writing in his 1998 classification, Rice recognized two of the subspecies of the common minke whale – B. a. scammoni (Scammon's minke whale) and a further taxonomically unnamed subspecies found in the Southern Hemisphere, the dwarf minke whale (first described by Best as "Type 3," 1985).[7]
On at least one occasion, an Antarctic minke whale has been confirmed migrating to the Arctic.[8][9] In addition, at least two wild hybrids between a common minke whale and an Antarctic minke whale have been confirmed.[8][9][10]
Diet[edit]
North Atlantic[edit]
Minke whales in the north Atlantic are observed to take a variety of food items.[25] Before 1993, minke whales in the north Barents Sea fed predominantly on capelin until stocks collapsed and the whales switched to krill as their primary prey type.[26] The minke whale population in the Norwegian Sea primarily feeds on adult herring[27] while krill, capelin, and sand eels are also recorded prey types.[28] In Scotland, sand eels are the most commonly observed prey species, followed by herring and sprat.[29] Seasonal variations are observed off of Finnmark, with krill the most popular prey type in the summer and cod in the autumn.[25] Stable isotope analysis from 2003 shows minke whales in the north Atlantic also feed on prey from lower trophic levels.[30]
North Pacific[edit]
Two stocks of minke whale are observed in the North Pacific: the "J stock" (Sea of Japan, Yellow Sea, East China sea) and the "O stock" (Okhotsk sea, west Pacific).[31] Seasonal variations in diet exist. J-stock whales' primary prey type is Japanese anchovy during May and June, Pacific saury in July and August, and krill in September. O-stock whales primarily feed on krill in July and August.[32] Most minke whales observed in 2002 (90.4%) fed solely on one prey species.[32]
Antarctic[edit]
Antarctic minke whales are diurnal feeders.[33] This minke whale population mainly feeds on Antarctic krill in offshore areas and ice krill in coastal areas on the continental shelf such as the Ross sea and Prydz bay.[34] The population has been recorded to forage on ten known species: five fish (Antarctic silverfish, Antarctic jonasfish, Antarctic lanternfish, Chionodraco, and Notothenia), four euphausiids (Antarctic krill, ice krill, Euphausia frigida, Thysanoessa macrura), and one amphipod (Themisto gaudichaudii).[34]
Population and conservation status[edit]
As of 2018, the IUCN Red List labels the common minke whale as Least Concern[35] and the Antarctic minke whale as Near Threatened.[36]
COSEWIC puts both species in the Not At Risk category.[37] NatureServe lists them as G5 which means the species is secure on global range.
Population estimates are generated by the Scientific Committee of the International Whaling Commission. The 2004 estimate yielded 515,000 individuals for the Antarctic minke stock.[38]