Devon Wildlife Trust The White-clawed crayfish is a freshwater, bronze-coloured crustacean with pale undersides to its claws - hence the name. It is under threat from an invasive and introduced species of crayfish.
As the UK's only native freshwater crayfish, the White-clawed crayfish is in decline due to the introduction of the non-native North American signal crayfish. This invasive species has brought disease to which our indigenous crayfish has no natural resistance. An omnivorous crustacean, the White-clawed crayfish eats invertebrates, carrion, water plants and dead organic matter. It inhabits small freshwater streams of a depth less than 1 metre, hiding underneath stones and rocks and in small crevices where they forage for food.
How to Identify
The White-clawed crayfish is small and bronze-coloured, with pale cream or rose undersides on its claws.
https://commons.wikimedia.org/wiki/File:Austropotamobius_pallipes.jpg
Connecting the Culm Once widespread in English streams and rivers, the white-clawed crayfish is now severely threatened and is close to extinction in Devon. The Upper Culm provides a fragile sanctuary to a small population of these fascinating creatures, which are the UK’s largest native freshwater invertebrate (ie an animal with a hard external skeleton). Only one other river in Devon also provides a home, and the situation is equally bleak in other English counties. It is classified as ‘endangered’ on the International Union for Conservation of Nature (IUCN) red list of threatened species and is at risk of global extinction.
One of the reasons we want to make the Culm a healthier river is to give the white-clawed crayfish a safe haven here in Devon. And, because the white-claw needs clear, unpolluted waters, it’s a good indicator of general river health.
It’s not only poor water quality that threatens the white-claw. An invasive sister species, the American signal crayfish, was introduced to this country around 40 years ago as a source of food. Much larger than the white-claw, it is more tolerant of poor water-quality and, fatally, it carries a virus called “crayfish plague” that kills white-claws. It also competes with our native crayfish for food. All told, signal crayfish are bad news for our native wildlife and they are present in large numbers on the Upper Culm, both upstream and downstream of the surviving white-claw colonies.
Since the white-claws of the Culm were re-discovered in 2010, they have been under close inspection and are now regularly surveyed. In 2018-19, through the Culm Community Crayfish project, funded by the Heritage Lottery Fund, we were able to recruit and train a team of crayfish surveyors (because they are endangered, you need a licence to survey for them). By monitoring closely and improving their habitat in the river, we can give them a fighting chance.
What can I do to help white-clawed crayfish?
Crayfish plague can be easily spread between sites, for example on wet angling kit, dogs or footwear.
There are some simple things that you can do to help to prevent the spread of crayfish plague such as following the ‘check, clean, dry’ code to stop the spread of crayfish plague.
- Get involved as a volunteer crayfish surveyor.
- Talk to us about how you could manage your land to help the white-clawed crayfish.
- If you are fishing in or using the river, check your equipment and clothing for live organisms and mud that could carry crayfish plague spores.
- Clean and wash all equipment, footwear and clothes thoroughly.
- Dry all equipment and clothing – some species can live for many days in moist conditions. Make sure you don’t transfer water elsewhere.
https://connectingtheculm.com/crayfish/
Buglife Crayfish Hub Welcome to the UK Crayfish Hub! Here you can find everything you need to know about our only native crayfish species, the White-clawed crayfish, its ecology, reasons for its decline, conservation projects and the latest scientific research on all aspects that concern crayfish in the UK.
You can also find information and advice on introduced crayfish species and how you can help the White-clawed crayfish. This fantastic freshwater invertebrate is very rare and its numbers are declining due to impacts from introduced crayfish species such as the North American Signal crayfish and from the damage to river and stream habitat.
The UK Crayfish Hub is a resource for everyone. It caters for ecologists, conservation professionals and managers plus people wanting to find out more about the White-clawed crayfish, invasive species and conservation projects running throughout the UK.
https://www.buglife.org.uk/resources/species-hub/crayfish-hub/
Wikipedia: Austropotamobius pallipes is an endangered European freshwater crayfish, and the only crayfish native to the British Isles. Its common names include white-clawed crayfish and Atlantic stream crayfish.
Distribution and ecology
It is found from the easterly Balkan Peninsula to Spain and reaches its northerly limit in Great Britain and Ireland, where it is limited to some regions only: its highest densities are in chalk streams. A. pallipes is the only crayfish found in Ireland, occurring over limestone areas in rivers, streams, canals, and lakes. It is absent from the more acidic waters of the west, and occurs in streams with a moderate flow alongside other freshwater invertebrates such as caddis fly, mayfly, and mollusc species. Trout and three-spined stickleback also occur in the same habitat. Tree roots and rocks in the banks provide shelter. Juveniles shelter in vegetation such as watercress and grass mats growing out of the bank.
https://en.wikipedia.org/wiki/Austropotamobius_pallipes
National Biodiveristy Network Austropotamobius pallipes
The NBN Atlas is a collaborative project that aggregates biodiversity data from multiple sources and makes it available and usable online. It is the UK’s largest collection of freely available biodiversity data.
https://species.nbnatlas.org/species/NBNSYS0000033009
