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Gloves off: scientists chart Chinese mitten crab invasion

Tuesday 20th September 2011

Become a nature detective and record the invasion of the alien Chinese mitten crab (Eriocheir sinensis) in rivers of England and Wales.

Scientists from a consortium of UK research institutes, including London’s Natural History Museum are asking the public to become nature detectives this autumn to better understand the full extent of the Chinese mitten crab invasion and the threat these crustaceans pose to our rivers and waterways. Anglers, waterway workers, boating enthusiasts and other nature lovers can use an online survey, to identify and record any sightings of the alien species. The recordings will be used by scientists to clarify the full distribution of the exotic crabs in English and Welsh rivers.

Chinese mitten crabs are now one of the most notorious aquatic invasive species featuring in the international list of the world’s 100 worst invasive species and they are here in the UK. They are regarded as a pest because they cause immense economic and ecological damage such as damage to fishing gear and unprotected river banks, block water systems as well as compete with native species for food and habitat.

Current records show that mitten crabs have established populations in the Thames, Medway, Ouse Washes, Humber and the Dee Estuary. There are a number of areas where our records are incomplete. Researchers are particularly interested in any 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 rivers and watersheds are also most welcome.

Becky Seeley, Marine Life Records Officer at the Marine Biological Association said "These crabs can be quite large and conspicuous and by helping us track them, the public and river users in particular will be doing something positive for the environment by helping to tackle their further spread."

Research and Government agencies and Nature lovers can report their finds by phone, email or online and upload their photographs by visiting

To find out more about mitten crabs and the survey visit and

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