Arctic char

The Arctic char or Arctic charr (Salvelinus alpinus) is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is circumpolar. It spawns in fresh water and populations can be lacustrine, riverine or anadromous, where they return from the ocean to their fresh water birth rivers to spawn. No other freshwater fish is found as far north; it is, for instance, the only fish species in Lake Hazen on Ellesmere Island in the Canadian Arctic. It is one of the rarest fish species in Britain and Ireland, found mainly in deep, cold, glacial lakes, and is at risk from acidification. In other parts of its range, such as the Nordic countries, it is much more common, and is fished extensively. In Siberia, it is known as golets (Russian: голец) and it has been introduced in lakes where it sometimes threatens less hardy endemic species, such as the small-mouth char and the long-finned char in Elgygytgyn Lake. The Arctic char is closely related to both salmon and lake trout, and has many characteristics of both. The fish is highly variable in colour, depending on the time of year and the environmental conditions of the lake where it lives. Individual fish can weigh 20 lb (9.1 kg) or more with record-sized fish having been taken by anglers in northern Canada, where it is known as iqaluk or tariungmiutaq in Inuktitut. Generally, whole market-sized fish are between 2 and 5 lb (0.91 and 2.27 kg). The flesh colour can range from a bright red to a pale pink. The arctic char was initially scientifically described in the salmon genus Salmo as Salmo alpinus by Carl Linnaeus in the 1758 edition of Systema Naturae, which is the work that established the system of binomial nomenclature for animals. Meanwhile, he described Salmo salvelinus and Salmo umbla, which were later considered as synonyms of S. alpinus. John Richardson (1836) separated them into a subgenus Salmo (Salvelinus), which now is treated as a full genus. The genus name Salvelinus is from German 'Saibling' – little salmon. The English name is thought to derive from Old Irish ceara/cera meaning ' red', referring to its pink-red underside. This would also connect with its Welsh name torgoch, 'red belly'. In North America, three subspecies of Salvelinus alpinus have been recognized. 'S. a. erythrinus' is native to almost all of Canada's northern coast. This subspecies is nearly always anadromous. S. a. oquassa, known as the blueback trout or Sunapee trout, is native to eastern Quebec and northern New England, although it has been extirpated from most of its eastern United States range. S. a. oquassa is never anadromous. Dwarf Arctic char has been classified as S. a. taranetzi. These scientific names are not generally accepted, however, as the names S. a. erythrinus and S. a. taranetzi usually refer to subspecies that are endemic to Siberia only. Arctic char are also found in Lake Pingualuit in the Ungava Peninsula, Quebec, a lake situated in an impact crater formed roughly 1.4 million years ago. Since the last glaciation, changing water levels are believed to have connected the lake with glacial runoff and surrounding streams and rivers, allowing char to swim upstream into the lake. Arctic char are the only fish found in the lake, and signs of fish cannibalism have been found. Arctic char are notable for exhibiting numerous, seemingly distinct morphological variants or 'morphs' throughout the range of the species. Consequently, Arctic charr have been referred to as the 'most variable vertebrate on Earth'. These morphs are often sympatric within lakes or rivers. Morphs often vary significantly in size, shape and colour. Morphs often demonstrate differences in migratory behaviour, being resident or anadromous fish, and in feeding behaviour and niche placement. Morphs often interbreed, but they can also be reproductively isolated and represent genetically distinct populations, which have been cited as examples of incipient speciation. In Iceland, Þingvallavatn is noted for the evolution of four morphs: small benthic, large benthic, small limnetic and large limnetic.