UK's char populations under threat

A team of leading experts on the Arctic char have published details on the conservation status of the fish in the UK.

The Arctic char, a member of the salmon family which is found in lakes across Britain and Ireland, was previously described as 15 separate species. However, most taxonomists now agree that the many forms actually represent a single polymorphic species complex made up of a single fish - Salvelinus alpinus.

Experts on S. alpinus say that the many distinct populations of the fish have a high conservation value because the level of variation seen between populations can be almost as high as it is between different species. It is also unusual among the fishes of Europe in that it has diversified rapidly into so many different forms, while others have not diversified very much at all.

However, the species is also in decline, and since most conservation measures regard all of the rare and distinct forms as a single fish species, some of the populations which are most at risk are not protected enough and a number of unique populations have already become distinct.

Ian McCarthy, Fran Igoe, Peter Maitland and Ian Winfield presented their findings on the conservation status of the species at the Char Network International Conference which are due to be published in a special edition of the journal Ecology of Freshwater Fish which is devoted to char.

They told delegates that in Scotland, only a small number of the 258 known populations have been studied and at least a dozen of those are now extinct and the picture was similar across the rest of the UK:

"In England, there are eight extant populations in Cumbria and four others extinct. The status of introduced stocks in England is uncertain but there is probably one population surviving in Yorkshire.

"In Wales, eight lakes with resident Arctic charr populations have been recorded, three of these populations are natural, one is extinct and four have been introduced. In Ireland, of the 74 known populations, approximately 30% are extinct. There is no evidence to indicate that introduced stocks (some of them from Iceland) in a small number of lakes have survived there."

The extinction of the various populations of char is believed to be due to a wide range of problems, including pollution, acidification, exploitation, engineering, aquaculture, introduced species and climate change.

The experts said that considerable work needs to be done to conserve the species, otherwise it will continue to be lost unless positive action is taken through local conservation management and national legislation to protect the genetic populations.

For more details see the paper: PS Maitland, IJ Winfield, ID McCarthy and F Igoe (2006) - The status of Arctic charr Salvelinus alpinus in Britain and Ireland. Ecology of Freshwater Fish.