Specieswatch: efforts are being made to preserve the Arctic char in Britain

Some 10,000 young char have been released into Kielder Water with the aim of saving this ancient fish, an important relic of our past

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.