( An exotic type of crab is spreading at ...)Exotic crab poised for widespread UK invasion

The Chinese mitten crab, brought to Britain during the last century in ships' ballast water, could cause devastating environmental problems if populations are not monitored and controlled, say the study's authors.

Researchers from the University of Newcastle upon Tyne carried out the first comprehensive modelling of the crab's migration through Europe and the UK. They compared the two and found the pattern of the crabs' ongoing invasion of the UK is similar to the population expansion in Europe earlier in the last century when the Continent experienced a major outbreak.

The study authors predict that the mitten crab - so called because its claws are coated with small clumps of dark brown fur, or mittens - has the potential to establish itself in all major UK estuaries in several years time.

Mitten crabs are unwelcome because they prey on protected UK native species such as the white-clawed crayfish and salmon eggs and fry. They also settle in river banks, burrowing into them and riddling them with bore holes up to half a metre long which may eventually cause the bank to collapse.

The Newcastle University study, published in the academic journal Biological Invasions, recommends that a nationwide monitoring and trapping system for the crab should be introduced before it is too late to control the population.

Chinese mitten crabs are already present in some of our waterways, including the Thames, Humber and Tyne rivers and parts of the North Sea and Channel coasts.

The study details how the UK colonisation of mitten crabs has increased on a large scale in recent years. From 1997-1999 the spread along the coast was 448km per year - nearly six times the average spread of 78km per year from 1976-1999. In rivers, the increased spread from 1995-1998 was 49km per year, around three times the
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Source:University of Newcastle upon Tyne