Arctic char
Overview
 
Arctic char or Arctic charr (Salvelinus alpinus) is both a freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 and saltwater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 in the Salmonidae
Salmonidae
Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes and graylings...

 family, native to Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

, sub-Arctic
Subarctic
The Subarctic is a region in the Northern Hemisphere immediately south of the true Arctic and covering much of Alaska, Canada, the north of Scandinavia, Siberia, and northern Mongolia...

 and alpine lake
Alpine lake
Alpine lakes are classified as lakes or reservoirs at high altitudes, usually starting around 5,000 feet in elevation above sea level or above the tree line....

s and coastal waters. No other freshwater fish is found as far north. It is the only species of fish in Lake Hazen
Lake Hazen
Lake Hazen is often called the northernmost lake of Canada, in the northern part of Ellesmere Island, Nunavut, but detailed maps show several smaller lakes up to more than farther north on Canada's northernmost island. Turnabout Lake is immediately northeast of the northern end of Hazen lake...

, on Ellesmere Island
Ellesmere Island
Ellesmere Island is part of the Qikiqtaaluk Region of the Canadian territory of Nunavut. Lying within the Canadian Arctic Archipelago, it is considered part of the Queen Elizabeth Islands, with Cape Columbia being the most northerly point of land in Canada...

 in the Canadian Arctic
Northern Canada
Northern Canada, colloquially the North, is the vast northernmost region of Canada variously defined by geography and politics. Politically, the term refers to the three territories of Canada: Yukon, Northwest Territories, and Nunavut...

. It is one of the rarest fish species in Britain
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, found only in deep, cold, glacial lake
Glacial lake
A glacial lake is a lake with origins in a melted glacier. Near the end of the last glacial period, roughly 10,000 years ago, glaciers began to retreat. A retreating glacier often left behind large deposits of ice in hollows between drumlins or hills. As the ice age ended, these melted to create...

s, mostly in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

, and is at risk from acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ification. It is also found in deep mountain lakes in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

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