At least 100 white-clawed crayfish have died in Northumberland, which is one of the endangered species’ last remaining strongholds.
The dead individuals were found with unusual orange patches on their shells. Extensive surveys have revealed that the mysterious marks are widespread in individuals across the River Wansbeck catchment, with affected individuals also found in catchment areas of the River Tyne and River Blyth.
The race is now on to protect the population.
“We will carry out rescues to move some crayfish into quarantine so they can be monitored, and if healthy, released back into the wild in future,” says Sarah Jennings, Area Environment Manager for the Environment Agency in the North East.
White-clawed crayfish mate in the autumn, and many females are currently carrying eggs. Egg-carrying females that are rescued from the affected areas will be taken to Northumberland Zoo, where the young will be reared and released at safe sites at some point in the future.
Other individuals will be quarantined in tanks at the National Trust’s Wallington Estate, where they will stay for a minimum of three months. If they remain healthy they will be released back to the wild, to sites that have been designated as safe.
It is hoped that this work, alongside ongoing efforts by the Northumberland Crayfish Partnership, will safeguard this endangered species.
Sarah says the work is “a positive step in what is still a concerning and developing situation.”
Alongside the rescue mission, the Environment Agency is currently monitoring thirty affected individuals. They hope this will give them a better understanding of the condition, and how deadly it is.
Various common crayfish diseases have already been ruled out by the Centre for Environment, Fisheries and Aquaculture Science. While some of the dead crayfish were carriers of a parasite known to be deadly, this parasite does not explain all of the deaths. Water pollution has also been ruled out as the cause.
Nick Allen, a National Trust Ranger at Wallington, says “here at Wallington we are focused on playing our part in the rescue mission alongside other organisations from the Northumberland Crayfish Partnership. This latest challenge to one of our country’s native species is a stark reminder of the increasing number of threats nature is facing.”
If you see any crayfish, alive or dead, leave it where it is and report it immediately to the Environment Agency on 0800 807060.
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