You can help in the fight against invasive mitten crabs


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The Chinese mitten crab (Eriocheir sinensis) is one of the world's 100 worst invasive alien species and an unwelcome visitor to the UK. You can help scientists in their quest to better understand the mitten crab invasion and the threat they pose to rivers and waterways.

Scientists from the Natural History Museum, University of Newcastle, Royal Holloway University of London, The Countryside Council for Wales and the Marine Biological Association are seeking the public's help in mapping the distribution of the mitten crab in rivers and waterways in England and Wales.

The scientists have appealed to anglers, waterway workers, boating enthusiasts or nature lovers in particular to identify and record any sightings of the alien crustacean online, by telephone, email or text. Further details are available at

Chinese mitten crabs are native to East Asia, and gained entry to Europe following accidental introduction to Germany in 1912 via the discharge of ships’ ballast water.

The first British record of this species was obtained in 1935 from the Thames drainage in Chelsea.  Since the late 1980s, the population in the Thames drainage has undergone a massive increase.

In the UK, the mitten crabs are responsible for immense economic and ecological damage. Their burrowing action damages unprotected river banks and clogs drainage systems, their sharp claws damage fishing gear (and the fish caught in them) and they compete with native species for food and habitat.

The Chinese mitten crabs are now established in the rivers Thames, Medway, Ouse Washes, Humber and the Dee Estuary.

The scientists are particularly interested in sightings in the Thames west of Windsor to beyond Reading; Tyne, Tees and Wear in the North East; Dee and Merseyside and from the Severn Estuary to the Isle of Wight in the South West. However records from other places are also welcome.

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