White-clawed Crayfish Project
What are White-clawed Crayfish?
Source: Yorkshire Wildlife Trust
White clawed crayfish (Austropotamobius pallipes) are the only native crayfish species in the UK. These freshwater crustaceans live in ponds, lakes, rivers, streams and canals.
They are:
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Nocturnal, hiding in refuges in the day and emerging at night to forage.
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Omnivourous, eating invertebrates, carrion, water plants and dead organic matter.
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Why are White-clawed Crayfish important?
The UK has a quarter of the world's population of White-clawed Crayfish. They are a key stone species and their presence or absence indicates the overall health of a freshwater habitat. White-clawed crayfish act as ecosystem engineers keeping waterways clean and healthy. They are also an important part of the food chain for various species including otters, herons and dragonfly larvae.
White-clawed Crayfish are protected in the UK under the Wildlife and Countryside Act, 1981, which means it is illegal to harm, disturb or take this species. Due to its recent decline, it is also listed as Endangered on the International Union for Conservation of Nature (IUCN) global Red List of Threatened Species.
Why are White-clawed Crayfish under threat?
Once widespread and common in England and Wales they have declined by 50-80% across their UK and European range in the past decade. This is a result of the release of non-native North American Signal Crayfish from crayfish farms since the 1970s.
These invasive crayfish:
- Out-compete native crayfish for food and places to live;
- Carry ‘crayfish plague’, which is fatal to our native species; and
- Are predatory, eating native crayfish and their eggs.
In addition, urban pollution and agricultural pesticides have impacted water quality in freshwater habitats, impacting populations.
Read a student blog about the spread of invasive Signal Crayfish in the area and their project to assess the biodiversity of water bodies in Coventry’s urban greenspaces:
White-clawed Crayfish conservation at the University of Warwick
There is no way of eradicating the invasive Signal Crayfish, so conservation efforts focus on ensuring native species do not become extinct. ARK sites are established and managed as isolated water bodies free from Signal Crayfish. Here, White-clawed Crayfish populations can establish and, if successful, some individuals can be translocated to other suitable sites to help ensure the survival of the species. We aim to establish a White-clawed crayfish population in the NAIC rill for future translocations to other suitable ponds in the area.
The project is:
- Funded by Natural England’s Species Recovery ProgrammeLink opens in a new window.
- A collaboration between Warwickshire Wildlife Trust, Coventry City Council and the University of Warwick.
NAIC rill Ark site
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Spring 2025 – environmental DNA testing undertaken by the School of Life Sciences confirmed no Signal Crayfish at this isolated site
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July/August 2025 – Refugia installed and enhancement of submerged and marginal vegetation
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September 2025 – White-clawed Crayfish translocated from a nearby site
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Long term monitoring of the White-clawed Crayfish population
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Management of the refugia and vegetation to ensure suitability
Biosecurity
If you are carrying out work in or near the rill, you can help stop the spread of invasive species by:
- CHECK– check your equipment and clothing for live plants and animals – remove anything you find and leave it at the site.
- CLEAN– clean and wash all equipment, footwear and clothing thoroughly with hot water if possible.
- DRY– dry all equipment for as long as you can before using elsewhere as some invasive species can survive for many days in damp conditions
- Please do not put anything into or remove anything from the rill.
- Report any crayfish sightings on iNaturalist.
- Do not enter the water or allow your dog to enter
- No angling
Project Photo Gallery
Scroll to see more pictures of the process. Read more about the the project hereLink opens in a new window.
Preparing the planters at the NAIC rill
Collecting the traps
Inspecting the traps
White-clawed crayfish
Some of the team members involved
Ecology and biodiversity on campus
