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[[File:Minke | [[File:Antarctic Minke Whale.jpg|400px|thumb|Antarctic minke whale underwater]] | ||
The '''Antarctic minke whale''' or '''southern minke whale''' (''Balaenoptera bonaerensis'') is a species of minke whale within the suborder of baleen whales. It is the second smallest rorqual after the common minke whale and the third smallest baleen whale. Although first scientifically described in the mid-19th century, it was not recognized as a distinct species until the 1990s. Once ignored by the [[whaling]] industry due to its small size and low oil yield, the [[Antarctica|Antarctic]] minke was able to avoid the fate of other baleen whales and maintained a large population into the 21st century, numbering in the hundreds of thousands. Surviving to become the most abundant baleen whale in the world, it is now one of the mainstays of the industry alongside its cosmopolitan counterpart the common minke. It is primarily restricted to the Southern Hemisphere (although vagrants have been reported in the North Atlantic) and feeds mainly on euphausiids. | The '''Antarctic minke whale''' or '''southern minke whale''' (''Balaenoptera bonaerensis'') is a species of minke whale within the suborder of baleen whales. It is the second smallest rorqual after the common minke whale and the third smallest baleen whale. Although first scientifically described in the mid-19th century, it was not recognized as a distinct species until the 1990s. Once ignored by the [[whaling]] industry due to its small size and low oil yield, the [[Antarctica|Antarctic]] minke was able to avoid the fate of other baleen whales and maintained a large population into the 21st century, numbering in the hundreds of thousands. Surviving to become the most abundant baleen whale in the world, it is now one of the mainstays of the industry alongside its cosmopolitan counterpart the common minke. It is primarily restricted to the Southern Hemisphere (although vagrants have been reported in the North Atlantic) and feeds mainly on euphausiids. | ||
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==Description== | ==Description== | ||
===Size=== | ===Size=== | ||
The Antarctic minke is among the smallest of the baleen whales, with only the common minke and the pygmy right whale being smaller. The longest caught off Brazil were an 11.9 meters (39.0 feet) female taken in 1969 and an 11.27 meters (37.0 feet) male taken in 1975, the former four feet longer than the second longest females and the latter five feet longer than the second longest males. Off South Africa, the longest measured were a 10.66 meters (35.0 feet) female and a 9.75 meters (32.0 feet) male. The heaviest caught in the Antarctic were a 9 meters (29.5 feet) female that weighed 10.4 metric tons (11.5 short tons) and an 8.4 meters (27.6 feet) male that weighed 8.8 metric tons (9.7 short tons). | [[File:Minke whale in ross sea.jpg|400px|thumb|Minke whale in the Ross Sea]] | ||
The Antarctic minke is among the smallest of the baleen whales, with only the common minke and the pygmy right whale being smaller. The longest caught off [[Brazilian Antarctica|Brazil]] were an 11.9 meters (39.0 feet) female taken in 1969 and an 11.27 meters (37.0 feet) male taken in 1975, the former four feet longer than the second longest females and the latter five feet longer than the second longest males. Off South Africa, the longest measured were a 10.66 meters (35.0 feet) female and a 9.75 meters (32.0 feet) male. The heaviest caught in the Antarctic were a 9 meters (29.5 feet) female that weighed 10.4 metric tons (11.5 short tons) and an 8.4 meters (27.6 feet) male that weighed 8.8 metric tons (9.7 short tons). | |||
At physical maturity, females average 8.9 meters (29.2 feet) and males 8.6 meters (28.2 feet). At sexual maturity, females average 8.1 meters (26.6 feet) and males 7.6 meters (24.9 feet). Calves are estimated to be 2.73 meters (8.96 feet) at birth. | At physical maturity, females average 8.9 meters (29.2 feet) and males 8.6 meters (28.2 feet). At sexual maturity, females average 8.1 meters (26.6 feet) and males 7.6 meters (24.9 feet). Calves are estimated to be 2.73 meters (8.96 feet) at birth. | ||
===External appearance=== | ===External appearance=== | ||
Like their close relative the common minke, the Antarctic minke whale is robust for its genus. Antarctic minkes lack the light gray rostral saddle present in the common and dwarf forms. All individuals possess pale, thin blowhole streaks trailing from the blowhole slits, which first veer left and then right – particularly the right streak. These streaks appear to be more prominent and consistent on this species than on either the common or dwarf minke. Most also have a variably colored – light gray, light gray with dark edges, or simply dark – ear streak trailing behind the opening for the auditory meatus, which widens and becomes more diffuse posteriorly. A light gray variably shaped double chevron or W-shaped pattern (analogous to a similar pattern seen on their larger cousin the fin whale) lies between the flippers. This broadens to form a light gray shoulder patch above the flippers. Like common and dwarf minkes, they have two light gray to whitish swaths, called the thorax and flank patches, the former running diagonally up from the axilla and diagonally down again to form a triangular intrusion into the dark gray of the thorax and the latter rising more vertically along its anterior edge and extending further dorsally before gradually sloping posteriorly to merge with the white of the ventral side of the caudal peduncle. A dark gray, roughly triangular thorax field separates the two, while a narrower dark gray shoulder infill separates the thorax patch from the shoulder patch. Two light gray, forward directed caudal chevrons extend from the dark gray field above, forming a whitish peduncle blaze between them. The smooth sided flukes, usually about 2.6 to 2.73 m (8.5 to 9.0 ft) wide, are dark gray dorsally and clean white (occasionally light gray to gray) ventrally with a thin, dusky margin. Some small, dark gray speckling may be present on the body. | Like their close relative the common minke, the Antarctic minke whale is robust for its genus. Antarctic minkes lack the light gray rostral saddle present in the common and dwarf forms. All individuals possess pale, thin blowhole streaks trailing from the blowhole slits, which first veer left and then right – particularly the right streak. These streaks appear to be more prominent and consistent on this species than on either the common or dwarf minke. Most also have a variably colored – light gray, light gray with dark edges, or simply dark – ear streak trailing behind the opening for the auditory meatus, which widens and becomes more diffuse posteriorly. A light gray variably shaped double chevron or W-shaped pattern (analogous to a similar pattern seen on their larger cousin the fin whale) lies between the flippers. This broadens to form a light gray shoulder patch above the flippers. Like common and dwarf minkes, they have two light gray to whitish swaths, called the thorax and flank patches, the former running diagonally up from the axilla and diagonally down again to form a triangular intrusion into the dark gray of the thorax and the latter rising more vertically along its anterior edge and extending further dorsally before gradually sloping posteriorly to merge with the white of the ventral side of the caudal peduncle. A dark gray, roughly triangular thorax field separates the two, while a narrower dark gray shoulder infill separates the thorax patch from the shoulder patch. Two light gray, forward directed caudal chevrons extend from the dark gray field above, forming a whitish peduncle blaze between them. The smooth sided flukes, usually about 2.6 to 2.73 m (8.5 to 9.0 ft) wide, are dark gray dorsally and clean white (occasionally light gray to gray) ventrally with a thin, dusky margin. Some small, dark gray speckling may be present on the body. | ||
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==Distribution== | ==Distribution== | ||
[[File:Balaenoptera acutorostrata Neko Harbour Antarctica.jpg|thumb|Minke whale in Neko Harbor]] | |||
Antarctic minke whales occur throughout much of the Southern Hemisphere. Vagrants have been reported in Suriname – an 8.2 meters (26.9 feet) female was killed 45 km (28 mi) upstream the Coppename River in October 1963; the Gulf of Mexico, where a 7.7 meters (25.3 feet) female was found dead off the U.S. state of Louisiana in February 2013; and off Jan Mayen (June) in the northeastern North Atlantic. | Antarctic minke whales occur throughout much of the Southern Hemisphere. Vagrants have been reported in Suriname – an 8.2 meters (26.9 feet) female was killed 45 km (28 mi) upstream the Coppename River in October 1963; the Gulf of Mexico, where a 7.7 meters (25.3 feet) female was found dead off the U.S. state of Louisiana in February 2013; and off Jan Mayen (June) in the northeastern North Atlantic. | ||
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===Migration and movements=== | ===Migration and movements=== | ||
Two Antarctic minke whales marked with "Discovery tags" – 26 cm (10 in) stainless steel tubes with an inscription and number engraved on them – in the [[Southern Ocean]] during the austral summer (January) were recovered a few years later off northeastern Brazil (6° – 7°S, 34°W) during the austral winter (July and September, respectively). The first was marked off Queen Maud Land (69°S 19°E) and the second southeast of the South Orkney Islands (62°S 35°W). Over twenty individuals marked with these Discovery tags showed large-scale movements around the Antarctic continent, each moving more than 30 degrees of longitude – two, in fact, had moved over 100 degrees of longitude. The first was marked off the | Two Antarctic minke whales marked with "Discovery tags" – 26 cm (10 in) stainless steel tubes with an inscription and number engraved on them – in the [[Southern Ocean]] during the austral summer (January) were recovered a few years later off northeastern [[Brazilian Antarctica|Brazil]] (6° – 7°S, 34°W) during the austral winter (July and September, respectively). The first was marked off Queen Maud Land (69°S 19°E) and the second southeast of the South Orkney Islands (62°S 35°W). Over twenty individuals marked with these Discovery tags showed large-scale movements around the Antarctic continent, each moving more than 30 degrees of longitude – two, in fact, had moved over 100 degrees of longitude. The first was marked off the Adélie Coast (66°S 141°E) and recovered the following season off the Princess Ragnhild Coast (68°S 26°E), a minimum of 114 degrees of longitude. The second was marked north of Cape Adare (68°S 172°E) and recovered nearly six years later northwest of the Riiser-Larsen Peninsula (68°S 32°E), a minimum of over 139 degrees of longitude. Both were marked and recovered in January. | ||
On 20 January 1972, a 49.5 cm (19.5 in) broken-off bill of a marlin was found embedded in the rostrum of a minke whale caught in the Southern Ocean at 64°06′S 87°14′E, providing indirect evidence of migration to the warmer tropical or subtropical waters of the Indian Ocean. | On 20 January 1972, a 49.5 cm (19.5 in) broken-off bill of a marlin was found embedded in the rostrum of a minke whale caught in the Southern Ocean at 64°06′S 87°14′E, providing indirect evidence of migration to the warmer tropical or subtropical waters of the Indian Ocean. | ||
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Antarctic minke whales are the main prey item of Type A [[Orca|killer whales]] in the Southern Ocean. Their remains have been found in the stomachs of killer whales caught by the Soviets, while individuals caught by the Japanese exhibited damaged flippers with tooth rake scars and parallel scarring on the body suggestive of killer whale attacks. Large groups of killer whales have also been observed chasing, attacking, and even killing Antarctic minke whales. Most attacks involve Type A killer whales, but on one occasion, in January 2009, a group of ten Type B or pack ice killer whales, which normally preyed on Weddell seals in the area by wave-washing them off ice floes, were observed to attack, kill, and feed on a juvenile Antarctic minke whale in Laubeuf Fjord, between Adelaide Island and the [[Antarctic Peninsula]]. | Antarctic minke whales are the main prey item of Type A [[Orca|killer whales]] in the Southern Ocean. Their remains have been found in the stomachs of killer whales caught by the Soviets, while individuals caught by the Japanese exhibited damaged flippers with tooth rake scars and parallel scarring on the body suggestive of killer whale attacks. Large groups of killer whales have also been observed chasing, attacking, and even killing Antarctic minke whales. Most attacks involve Type A killer whales, but on one occasion, in January 2009, a group of ten Type B or pack ice killer whales, which normally preyed on Weddell seals in the area by wave-washing them off ice floes, were observed to attack, kill, and feed on a juvenile Antarctic minke whale in Laubeuf Fjord, between Adelaide Island and the [[Antarctic Peninsula]]. | ||
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