Breeding may occur throughout the year, but there seems to be a calving peak in winter. Males in the North Pacific reach sexual maturity at about 6.9 m in length and females 7.3 m at ages of 5 to 8 and 6 to 8 years respectively (based on growth years in ear plug cores). Natural History & Ecologyįemales on average reach a length of 9 metres, and the average length of males is 8.5 m and up to 12 tonnes in weight. At least 3 geographically-isolated minke whale populations are recognised in the North Pacific, North Atlantic and the Southern Hemisphere at this time. The species is frequently seen in inshore northern and western coastal waters of the UK, and occasional records have been reported from the channel coast of mainland Europe, the Mediterranean, and the Azores and Portugal. Pregnant females seem to move farther north during the summer than lactating and immature females, but in some temperate waters these animals are present year round. Whilst there is little direct evidence to demonstrate long distance migration, seasonal variation in abundance and distribution suggests that the species probably undergoes some migration from higher latitudes in summer to lower latitudes in the winter. Like other balaenopterids, however, they tend to be found in equatorial waters during the winter and in polar waters in summer, although the species seems to be widely distributed in all seasons and migrates in a manner hard to predict from year to year. Minkes are distributed from the tropics to the ice edges. They are also known to breach more often than other baleen whales, leaping clear of the surface and re-entering the water head-first or with a body splash. During the dive, minke whales typically arch their tail stock but never "fluke-up". A typical dive sequence is 3 to 5 blows at intervals between 15 seconds to 1 minute, followed by a dive lasting from 2 to 4 minutes although minkes have been recorded underwater for 20 minutes or longer. The surfacing and blow rates of minke whales tend to be less regular than those of the larger baleen whales and may also be affected by the presence of vessels, the time of day, the activity of the animal and even the environmental conditions. On surfacing, the dorsal fin typically becomes visible simultaneously with the audible blow, although the blow is rarely visible even in the calmest of conditions. Minke whales are fast moving and may swim at speeds in excess of 20 km per hour. The longest of these ends slightly anterior to the navel. Between 50 to 70 thin, ventral pleats can be counted on the throat and belly. The baleen plates (between 230-330 pairs) are characteristically white or cream in colour. The broad tail flukes may be pale grey, blue-grey or white on the underside, and usually have a dark margin. As in fin whales, minke whales sometimes also have a light chevron behind the head and two regions of light grey on each side (one just above and behind the flipper and the other just in front of and below the dorsal fin). The most conspicuous feature for identification is a diagonal white band on the upper surface of each flipper (see photo right), the extent and orientation of which varies from individual to individual. The back of the minke is black, brown or dark grey in colour, whereas the belly and underside of the flippers are usually white. It has a sharply pointed snout, slender streamlined body, and a tall falcate dorsal fin positioned slightly less that two thirds of the way back from the tip of the rostrum (as in Sei whales). Species: Balaenoptera acutorostrata Lacépède, 1804 IdentificationĪt a maximum length of 10.7m, the minke whale ( Balaenoptera acutorostrata) is the smallest member of the rorqual whale family of baleen (filter-feeding) whales. Family: Balaenopteridae Subfamily: Balaenopterinae
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