Lifeline for endangered crayfish as National Trust creates first ‘Ark’ site

Press release
A native white-clawed crayfish at Wallington, Northumberland
Published : 15 Mar 2022

One of the UK’s most endangered native species has been given a fresh chance of survival thanks to a newly created refuge on a National Trust estate.

An old cattle drinking hole at Wallington in Northumberland will become the charity’s first ‘Ark’ site for the white-clawed crayfish, the country’s only indigenous crayfish.

Often compared to a miniature lobster in appearance, the white-clawed crayfish is so vulnerable that experts fear it may become extinct.

Populations have more than halved across Europe in recent decades largely due to the spread of the American signal crayfish, a bigger species which was introduced to the continent in the 1970s as a restaurant delicacy. 

As well as outcompeting white-clawed crayfish for food and habitat, the signal crayfish carries a deadly plague that while harmless to itself, can decimate white-clawed populations in a matter of weeks. 

Now the National Trust hopes to give the native species a lifeline by moving up to 100 of the crustaceans into an ‘Ark’ site – a safe waterbody where it is hoped they will breed. 

The crayfish will be taken from the River Wansbeck which runs through the estate and is deemed to be one of the best habitats for white-clawed crayfish left in the UK.

The River Wansbeck on the Wallington Estate is one of the best habitats left in the UK for white-clawed crayfish
Two visitors walking over the bridge over the River Wansbeck, Northumberland
The River Wansbeck on the Wallington Estate is one of the best habitats left in the UK for white-clawed crayfish

Rangers have spent 15 months taking water samples, surveying, applying for a handling licence and most recently, turning the 200-year-old cattle drinking hole into an ideal home for the crayfish, using dry-stone walling techniques to create crevices that imitate their natural habitat. 

The site is fed by a spring, with the water flowing over significant barriers before it reaches the Wansbeck, meaning the chances of signal crayfish or plague entering are low.    

Matthew Fitch, National Trust Ranger at Wallington, said: “This species is very much on a knife edge. It’s so important we shore up the healthy populations, like the one we’re fortunate to have here on the Wansbeck, as quickly as we can, to make sure it doesn’t vanish from our rivers altogether. 

“The ‘Ark’ site will not only give us a safe haven for white-clawed crayfish at Wallington but also contribute to the long-term protection of the animal, as the crayfish that are kept here can in theory be used to repopulate other waterbodies.”  

The new refuge will also become a focal point for the 250,000 annual visitors to the estate, as will a display tank in the reception area, where the public can see crayfish in close detail.  

Wider efforts to protect Wallington’s 54km of waterways are in progress too, including work to stop riverbanks eroding and soil spilling into the water, thanks to funding from the Government’s Green Recovery Challenge Fund, which has also paid for the display tank.

Talks and engagement activities are planned to educate people about this unsung species – and crucially how people can help stop the spread of crayfish plague. 

The disease can be carried unwittingly on boots, dog paws and fishing equipment between rivers and waterways, and can survive on wet or muddy items for up to three weeks. 

Matthew continued, “We really need people to help us by following the steps of clean-check-dry if they’ve been in water. That means cleaning boots, dog paws, or any fishing rods or boat equipment, giving everything a check for mud, animal or plant materials, and then leaving it to dry for as long as possible before using it in another body of water.”

The Trust is working in partnership with the Environment Agency, Northumberland Wildlife Trust, Northumberland National Park and the Rivers Trust to reinforce this message and protect the endangered species across the North East of England.

Ian Marshall, Environment Agency Biodiversity Technical Specialist in the North East and white-clawed crayfish National Species Lead, has just published a best practice reference book to help future white-clawed conservation efforts across the country, in conjunction with Bristol Zoological Society. 

He said: “White-clawed crayfish are under threat nationally from the rapid spread of non-native crayfish and the diseases they carry, but we are fortunate to have some of the best populations here in Northumberland. 

“They are vital to our ecology, helping to keep our waterways clean and providing a source of food for other native species.  

“The Northumberland Crayfish Partnership is working hard to better protect them and this brilliant project at Wallington is one of many big plans to make 2022 the best year yet for the recovery of native crayfish across the region.” 

Staff will closely monitor the new refuge and expect to translocate a second batch of crayfish in September. Twenty willow trees have been planted along its banks, with the trees’ roots providing further homes for the crayfish. 

Any changes to the site are being made in keeping with the aesthetic of the historic estate, with traditional materials such as dry-stone walls and cobbles used wherever possible.

White-clawed crayfish are the only native freshwater crayfish in the UK. They can grow up to 12cm in length and weigh around 90g. They are listed as endangered on the ICUN Red List and are a European Protected Species.

Known as a ‘keystone species’, they are an indicator of healthy rivers and play an important role in freshwater ecosystems – providing food for fish and otters and helping break down leaf litter.

If you see any crayfish, alive or dead, leave it where it is and report it immediately to the Environment Agency on 0800 807060. If possible, take close-up photos of the crayfish to help identify the species. It is illegal to handle or remove crayfish from the water without the correct licences.