Natural Resources Wales says a Welsh conservation programme to save a highly endangered species is celebrating a milestone after a captive-bred population has successfully spawned in the wild for the first time.
Experts released native white-clawed crayfish in a tributary of the river Irfon near Builth Wells between 2012 and 2014.
Now they have found first-generation wild crayfish in the area – showing that a new population has been established.
The white-claw is Britain’s only native crayfish and without intervention the species could become extinct in mainland Britain in 20 to 30 years.
Over the last decade the species has declined by up to 80 per cent world-wide.
In the wild they have less than a 10 per cent chance of surviving to adulthood, compared to around 80per cent in the hatchery.
To date more than 5,000 captive-reared crayfish have been released into carefully selected ‘Ark’ sites in Wales.
The programme aims to offset the damage caused to the native crayfish population by the non-native American signal crayfish, climate change, habitat degradation and the impact of pollution on water quality.
The American signal crayfish, introduced for food production in the 1970s and 80s, carries a plague which affects only the white-clawed species.