Specieswatch: efforts are being made to preserve the Arctic char in Britain
The Arctic char, Salvelinus alpinus, is a remarkable survivor from the ice age in Britain, having been trapped in various lakes and Scottish lochs for 10,000 years. As a result, if you manage to catch one, the fish may look considerably different from those in other lakes, because they have had many generations to evolve to survive in local conditions after being cut off from the oceans when the ice retreated.
Some scientists went to the trouble of designating each of these populations of Arctic char as separate species because of these different characteristics, but this idea has generally been dropped as too difficult, not least because there are dozens of cut-off populations, some yet to be described.
Further north than Britain in colder waters, particularly Norway, char are numerous, dominating some rivers in the Arctic regions too cold for salmon and trout. Like salmon these char migrate out to sea, returning to spawn, but do not die with the effort and can return many times. In the UK and Ireland they have adapted to live all their lives in cold freshwater.
It is 10 years since a definitive look at the status of this fish in Britain. The char generally only thrives in a temperature below 8C so Scotland has the largest share where, incidentally, char is spelt with two rrs, further adding to confusion.
In 2006 it was reported in Ecology of Freshwater Fish that there had been 258 natural populations recorded in lochs in Scotland, with 12 already having gone extinct.
The reasons for extinction are pollution, acidification of waters, and global warming.
It is this last threat that is the biggest to the eight existing populations in north-west England, four others already having been lost. Of the eight lakes in Wales with char, three were natural populations and the rest introduced, while Ireland had once had 74 places with char, of which 30% have become extinct.
Even these numbers are approximate; in at least a third of the places, the evidence of the fish being present dates from so long ago that the current status is classed as “uncertain”.
All this is undesirable, say scientists, because the char is a valuable fish, not least because it is very good to eat and full of natural oils, similar to its close relations, brown trout and salmon. In the right conditions successful attempts have been made to farm char. As a result it can be found occasionally on restaurant menus, but because of its rarity is usually expensive.
Apart from the economic and nutritional value of char, the fish is an important ancient relic of our past, so efforts are being made to preserve the species in the UK. One of the difficulties is that the char is already on the southern limit of its range and needs cold water. The manmade reservoir Kielder Water in Northumberland fits the bill and in 2013 10,000 young char were released there. They were bred from a population in Ennerdale in the Lake District that was threatened with extinction because surrounding coniferous woodland had turned the water acid.
It is still too early to know whether the adults in the cold depths of the lake will live to breed successfully and provide both a lucrative fishery for Kielder and a safe place for the char until the water quality in Ennerdale can be restored.