More than 1,000 native white-clawed crayfish have been released into a Welsh river as part of continued efforts to save the species from extinction.
This is the third year Natural Resources Wales officers have captive reared and released the juvenile crayfish working in conjunction with the Wye and Usk Foundation.
To date more than 2,700 captive reared crayfish have been released into the wild in a bid to offset the damage caused by the non-native American signal crayfish, climate change and the impact of pollution on habitat and water quality to the native crayfish population.
The one-year-old crayfish were reared at Natural Resources Wales Cynrig Fish Culture Unit and have been released into specially selected ‘ark’ sites on a tributary of the River Irfon, near Builth Wells.
These sites are chosen for their good habitat and water quality and because they are free from non-native crayfish and crayfish plague - a lethal fungus-like disease carried by the North American invaders.
Early signs suggest the project has been a success with crayfish found at release sites 15 months after the initial introduction.
The white-claw is Britain’s only native crayfish and experts believe that without intervention there is real risk of the species becoming extinct from mainland Britain within the next 20 to 30 years.
They play an important role in aquatic ecosystems and thanks to their sensitivity to chemical pollution they are a useful indicator of water quality.
Oliver Brown, Natural Resources Wales, said: “Establishing a healthy population of native white-clawed crayfish would be a good sign that we are creating a better environment in Wales.
“It’s under threat from the invasive American Signal invader, which can devastate aquatic wildlife by eating insects and fish eggs – and in doing so, causing long-term damage to fish stocks. It also burrows into riverbanks to nest, making them less stable, and increasing the risk of flooding.
“Rearing in excess of 1,000 crayfish in one production cycle is a real breakthrough for us.
“With few naturally abundant populations left in Wales, captive rearing is likely to be the most efficient way of providing crayfish to stock ark sites.
“Working with the Wye and Usk Foundation has allowed us to release larger numbers of this threatened species back into the wild to help ensure its survival.”
This project is a small part of the wider work taking place to mitigate the many threats facing the white-clawed crayfish.
Elsewhere, water quality and habitats are being restored to a condition suitable for the crayfish to flourish.
The project is part of the European Union’s Life+ funded Irfon Special Area of Conservation Project (ISAC).