The vendace has been confirmed as extinct at Bassenthwaite
A rare fish dating back to the Ice Age has been declared extinct at one of its few historic homes in Britain.
However, the vendace is now thriving at a new site in Loch Skene in Dumfries and Galloway after its spawn was introduced there in the 1990s.
Extensive surveys have confirmed the vendace has died out at Bassenthwaite Lake in the Lake District.
The situation means nearby Derwent Water is its only remaining native site in the UK.
The vendace is a herring-like fish which can be traced back to the Ice Age.
Historically, it has only been known at four sites - Bassenthwaite Lake and Derwent Water in the Lake District and the Castle and Mill Lochs in Lochmaben, Dumfries and Galloway.
The Castle Loch population disappeared at the beginning of the 20th Century and Mill Loch shortly before the end of the century.
It has now met a similar fate at Bassenthwaite.
Due to the decline in numbers, conservationists took action about a decade ago.
Spawn from the struggling Bassenthwaite population were taken to Loch Skene in southern Scotland.
They have fared so well that they have outlived their "parent" stock.
The Scottish loch now boasts a population density significantly higher than that remaining in Derwent Water.
Dr Colin Bean of Scottish Natural Heritage said the scheme had been a great success.
"It has been incredibly successful - beyond all expectations," he said.
"We have really taken vendace back from the brink here."
He added that the lessons learned at Loch Skene could be valuable in the conservation of other types of fish.
"The vendace population in here is in an incredibly healthy state, probably better than some of the parent populations ever did," he said.
"We've learned an incredible amount from stocking vendace in here and that's a lesson we can learn for trying to save other fish species."