The discovery of the White-clawed crayfish population at Luddenden Brook has been described as an “exciting” find by the Environment Agency, which discovered the species alongside partners at the Reviving Calderdale’s Rivers project.
The species of freshwater crustaceans has been listed as rare and threatened species under Section 41 of the Natural Environment and Rural Communities Act (2006) since the introduction of the American signal crayfish in the 1970s saw a sharp reduction in numbers.
The American species not only transfers a fatal disease, referred to as “crayfish plague”, but it also outcompetes the white-clawed crayfish for food.
Dan Chadwick, fisheries technical officer from the Environment Agency in Yorkshire, said: “We’re delighted with this discovery. The white-clawed crayfish is in very real danger of disappearing from the UK so to confirm that a population we thought was lost is flourishing is exciting.
“We’ll be working with partners including Yorkshire Wildlife Trust, Calderdale Council and Calder Rivers Trust to create better habitats and ensure this rare species can survive and thrive. It gives us real hope that there might be further populations in the Calder river catchment.”
The Environment Agency is now calling on people to ‘Check, Clean, Dry’ their clothing to try to make sure they are not moving crayfish from where they have been found.
Tim Selway, Environment Agency biodiversity technical officer, said: “Signal crayfish have rapidly spread across the country and moving just one into a river can wipe out an entire population of the white-clawed species, killing hundreds of thousands of them. And once the invasive signal becomes established in a river there is currently no way to get rid of them.”
According to experts, the rare species plays a huge role in keeping waterways clean and is an important part of the river ecosystem, acting as food for other native species.
Elliot Baxendale from Yorkshire Wildlife Trust said: “Through partnership work it’s fantastic to see the rediscovery of the white-clawed crayfish in Luddenden Brook. This endangered species needs all the help that it can get and this can be as little as following the Check, Clean, Dry guidance to help ensure their survival in our shared interconnected eco systems.
Elsewhere in the UK, the Environment Agency worked with Northumberland Rivers Trust to move a large number of the species to refuge sites, known as ‘Arks’.