A population of rare Arctic char has been discovered in a Kerry lake.
The finding reverses "a depressing trend" of extinction of the species in many Irish lakes due to pollution and the introduction of predators, according to scientists conducting a survey of fish.
The scientists working with the Irish Char Conservation Group discovered the distinctive red-bellied fish, one of our oldest species, when carrying out a routine survey of Lough Namona near Waterville at a depth of 15 metres.
The Lough Namona char are thought to represent an old line close to the ancestors of the Arctic char that colonised Irish lakes when the Ice Age began to thaw some 18,000 years ago.
Scottish fish expert Ron Greer said enough char had been recorded to indicate the lake had a self-reproducing population. The discovery was "exciting", Mr Greer said.
Dr Fran Igoe, scientific adviser to the group, said the discovery was a boost as recently they had been reporting depressing extinctions. Five populations of char had been confirmed in Kerry since 2003 and not many European countries let alone Irish counties had such a record, Dr Igoe said.
Unless local planning was sensitive in areas where Arctic char populations survive, he added, "we can expect to see many more extinctions".
Char, a salmon-like fish, are found mainly in landlocked glacial lakes and survive only in the purest of waters. Because of their isolation each population has a unique genetic make-up.
Once recorded in up to 70 Irish lakes, it is estimated that about a third of the char populations has been lost due to pollution, the introduction of non-native fish, habitat destruction, forestry and acidification, and possibly global warming.
In recent years the char populations of Lough Corrib and Lough Erne have disappeared, along with those in at least three lakes in Co Clare. Over-fishing is not thought to be a factor.