After draining a 50-metre section of water for lock repairs, our staff have found, rescued and relocated this rare protected species, which has seen its population plummet in recent years because of the increasing threat from invasive signal crayfish.
Following a virulent outbreak of the Aphanomyes Astaci plague in the 1970s white-clawed crayfish, the UK's only native crayfish species, has been on a steady decline. The plague, started by the invasive signal crayfish species from North America, has spread across the UK's waterways and is widely expected to wipe out large populations.
Now on the endangered list, other predators include the red swamp, noble and narrow-clawed (or Turkish) crayfish. These larger, ‘meatier' species were originally introduced to stock crayfish farms, but their escape and spread has been quick and has caused huge damage to native populations.
Phillippa Baron, ecologist for the Canal & River Trust, who discovered the colony said: “This was a really important discovery for us as we've done a couple of crayfish investigations and found very few. They have been depleting in numbers over the last 30 years since the American signal crayfish were brought to England as fashionable seafood.
“The hidden underwater crevices which our dry stone walls provide are ideal habitats for them. It's therefore crucial we do what we can to protect their populations and the most direct way we can help is to ensure their survival during and after our repair works and relocate them to safe sites.
“Sadly, at the moment there is no known way to eradicate the non-native crayfish which have become very dominant because of their predatory instincts and the plague they've spread.”
The discovery comes as part of our £45 million, five-month maintenance programme to 2,000 miles of waterways across England and Wales.Between November and March essential restoration and repair to locks,aqueducts, reservoirs and tunnels are carried out for the benefit of the 32,000 boats and 13 million towpath visitors that visit them each year.