White-clawed crayfish (Austropotamobius pallipes) are Britain’s only native crayfish species. Their population has drastically declined in recent years due to the introduction of non-native crayfish species, habitat destruction and pollution. Now, catastrophe has struck in one of their last remaining strongholds – Northumberland.
At least one hundred individuals, with peculiar orange patches on their shells, have been found dead in the River Wansbeck’s catchment area.
Extensive surveys have revealed that the mysterious orange patches are widespread in individuals across the River Wansbeck catchment. Affected individuals have also been found in catchment areas of the River Tyne and River Blyth.
White-clawed crayfish can live for up to twelve years and are ecosystem engineers, playing a significant role in keeping freshwater habitats clean. They are also an important food source for many species, including otters. That a mysterious condition is suddenly killing this endangered species in such numbers is a huge worry for conservationists.
The race is now on to protect the remaining individuals.
“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.
Some 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.
White-clawed crayfish mate from September to November, so many of the rescued females are carrying fertilised eggs. These females – known as ‘berried’ females – will be taken to Northumberland Zoo instead, where the young will be reared before also being released to safe sites.
It is hoped that this work, alongside ongoing efforts by the Northumberland Crayfish Partnership, will safeguard this 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 in order to understand more about the deadly condition. Various common crayfish diseases have already been ruled out by the Centre for Environment, Fisheries and Aquaculture Science. Water pollution has also been ruled out as the cause.
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