Crayfish in the Corve (aka Happy Snappy!)

Pacifastacus leniusculus crayfish image credit: GB INNS

Pacifastacus leniusculus crayfish image credit: GB INNS

The White-clawed crayfish (Austropotamobius pallipes) is the only native species of freshwater crayfish in the British Isles. It is under threat and rapidly decreasing in range. They look like mini lobsters and tend to thrive in clean, well-oxygenated rivers (see: 

The main threats to this species are the invasion of non-native crayfish - the American Signal crayfish (Pacifastacus leniusculus) - which are able to out-compete White-clawed crayfish for food and habitat. American Signal crayfish also carry the crayfish plague (Aphanomyces astaci), a fungal disease, which rapidly kills White-clawed crayfish. Find out more here:

In Shropshire, populations have declined dramatically, the River Corve in South Shropshire did once have strong numbers of White-clawed crayfish. River pollution and reductions of habitat quality are also threats in many areas. Without action for conservation, White-clawed crayfish will continue to be lost from sites and whole rivers. 

We are also aware that there is very low knowledge of crayfish in Shropshire and would like to involve the community in survey work along stretches of their local river, helping us to raise awareness of the importance of keeping waterways clean for wildlife and securing the presence of crayfish in our rivers. 

To help conserve the species in Shropshire, the Happy Snappy project will include:

- Surveying the River Corve for White clawed crayfish and invasive Signal Crayfish; 
- Training a volunteer survey team to undertake crayfish (and other native species) surveys and help with ongoing river monitoring along the River Corve; 
- Identifying potential 'Ark sites' for the White clawed crayfish - Ark sites are isolated, self-contained sites which can support the establishment of healthy, self-sustaining populations, safe from non-native crayfish and crayfish plague.

This project is kindly sponsored by Tesco Bags of Help (, and was voted for by the wonderful people around Ludlow - thank you! 

Crayfish survey training evening for volunteers: 23rd July, 6pm, Pam's Pools
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