Sei whale

The sei whale (/ˈseɪ/ or /ˈsaɪ/) (Balaenoptera borealis) is a baleen whale, the third-largest rorqual after the blue whale and the fin whale.[3] It inhabits most oceans and adjoining seas, and prefers deep offshore waters.[4] It avoids polar and tropical waters and semienclosed bodies of water. The sei whale migrates annually from cool and subpolar waters in summer to winter in temperate and subtropical waters, with a lifespan of 70 years.[5]

Reaching 19.5 m (64 ft) long and weighing as much as 28 t (28 long tons; 31 short tons),[5] the sei whale consumes an average of 900 kg (2,000 lb) of food every day; its diet consists primarily of copepods,  krill, and other zooplankton.[6] It is among the fastest of all cetaceans, and can reach speeds of up to 50 km/h (31 mph) (27 knots) over short distances.[6] The whale's name comes from the Norwegian word for pollock, a fish that appears off the coast of Norway at the same time of the year as the sei whale.[7]

Following large-scale commercial whaling during the late 19th and 20th centuries, when over 255,000 whales were killed,[8][9] the sei whale is now internationally protected,[2] although limited hunting occurs under a controversial research program conducted by Japan.[10] As of 2008, its worldwide population was about 80,000, less than a third of its prewhaling population.[11][12]