Crayfish hatchery and nursery
The white-clawed crayfish (WCC) is the UK’s only indigenous freshwater crayfish and has seen a decline of over 70% in the South West in the last 50 years.
The WCC is now recognized as globally Endangered (IUCN) and is protected under the Wildlife and Countryside Act 1981.
Why conserve crayfish?
Keystone Species
WCC are native to Europe and are the only native crayfish species found in the UK and Ireland. They play a crucial role in maintaining
biodiversity by occupying a specific niche in freshwater ecosystems. They are an important part of the food chain for otters, fish and birds, and their disappearance could disrupt the balance of aquatic ecosystems.
Indicator Species
WCC are considered an indicator species, meaning their presence or absence can indicate the overall health of a freshwater habitat.
Their sensitivity to environmental changes, pollution, and habitat degradation makes them valuable indicators for assessing the well-being of rivers and streams.
Invasive Species Threat
The introduction of non-native crayfish species, such as the signal crayfish, poses a significant threat to the WCC. The invasive species outcompete native crayfish for resources and can carry a devastating
crayfish plague.
Legal Protection
WCC are a protected species in the UK due to their declining populations. In conservation terms, the white-clawed crayfish is on a
par with tigers and rhinos - a globally Endangered species battling for survival.
Threats
The sharp decline in the species has been driven by habitat degradation, pollution, deteriorating river water quality, but primarily the introduction of the invasive, non-native American signal crayfish and its associated pathogens.
Signal crayfish not only carry a deadly crayfish virus which kills WCC, but they also prey and outcompete WCC for food.
WCC are a smaller, less aggressive species which produce fewer young.
Signal crayfish produce greater numbers of young and mature faster.
Unlike our native crayfish species, signal crayfish burrow extensively into riverbanks and predate coarse fish and eggs. This means that there is also a risk of soil erosion, flooding and deterioration of ecosystem health if they are present.
How we are saving them
At present there is no way of eradicating the invasive American signal crayfish or effectively reducing their numbers in our rivers, without causing unacceptable environmental damage to other aquatic species.
Conservation methods are focused on ensuring whiteclawed crayfish populations do not become extinct by establishing a Devon crayfish hatchery and subsequent breeding populations in ‘ark sites’ ahead of potential future river re-introductions.
Addressing deteriorating water quality in our rivers is an equally important aspect but sadly there are no quick solutions due to the scale and complexity of the land management and wastewater issues involved.
Contact details
charlotte.mead@wildwoodtrust.org
The Saving Devon’s Native Crayfish project is managed by the Wildwood Trust (Devon) and is funded through Natural England’s Species Recovery Programme. The project is also supported by South West Water and by a Devon Environment Foundation grant.
