Species Spotlight: Endangered white-clawed crayfish

We are continuing our Species Spotlight as part of our Reverse the Red initiative pledge to conserve and protect 97 species facing major threats in the wild.

Previously we have focused on the Critically Endangered turquoise dwarf gecko, the Critically Endangered Negros bleeding-heart dove, and the Critically Endangered blue-eyed black lemur. The next of the six flagship species in the spotlight is one of the UK’s most threatened species, the Endangered white-clawed crayfish, Austropotamobius pallipes.

Here at Bristol Zoological Society, we have been working to protect white-clawed crayfish since 2008 and are a leading partner in the South West Crayfish Partnership (SWCP).

This small and seemingly insignificant invertebrate is under threat due to habitat loss, fragmentation, pollution, and the invasive non-native North American signal crayfish, which not only outcompete them for food and habitat, but also spread a crayfish plague that is usually deadly to the species. However, a few white-clawed crayfish populations have been discovered in mainland Europe which are resistant to crayfish plague, and we are on the hunt for similar populations in the UK!

The Endangered white-clawed crayfish is an ‘ecosystem engineer’, working in harmony with our aquatic ecosystem, unlike the North American signal crayfish which can cause considerable damage. White-clawed crayfish maintain waterways by foraging for invertebrates, carrion, water plants and dead matter, keeping the aquatic environment clean for other species to thrive. Britain’s only native crayfish, these small and bronze-coloured, omnivorous crustaceans have pale undersides on their claws and can be found in freshwater streams and lakes hiding in crevices and under stones.

The species is listed as Endangered by the IUCN and here at Bristol Zoological Society we play a major role in the protection of the species, which includes focusing our efforts on producing captive-born populations at our hatchery in Bristol, for wild release.

Since the project began, the team have released more than 3,000 captive-born white-clawed crayfish into the wild into carefully chosen sites free from the American signal crayfish.

The South West white-clawed crayfish conservation effort has five key elements:

• Mapping of native and non-native crayfish in the South West river catchments.

• Establishing safe ark sites, which high-risk populations of white-clawed crayfish can be translocated into.

• Breeding and rearing white-clawed crayfish at the Bristol Zoological Society hatcheries to facilitate research and to populate ark sites and river supplementations.

• Running outreach programmes to raise awareness of this endangered species, encourage biosecurity and stop the spread of non-native invasive species.

• Conducting a pilot trial and research study investigating methods of controlling invasive non-native crayfish.

  
  The Society, in partnership with the SWCP, has achieved a great deal since setting up the project, including establishing 21 ark sites in the South West for both wild-caught and captive-born white-clawed crayfish. More than 4,000 wild white-clawed crayfish have been moved into ark sites from threatened rivers and the Society has bred crayfish from six different river catchments. These ark sites not only provide a safe haven for this endangered species, but also provide excellent nature reserves for many of our other native species. A pilot trial for invasive crayfish control has also been set up at a local lake.

Our native species conservation work is sponsored by our partners at Marshfield Farm Ice Cream.

Find out ways you can help protect white-clawed crayfish and save the ecosystem on your doorstep here or find out ways you can support these projects through Bristol Zoological Society here.

More information about our conservation work can be found by clicking the button below.