Invasive crab could be used for food

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An invasive alien species of crab wreaking environmental havoc on the Thames can be harvested for food to keep their numbers down, according to scientists.

The Chinese mitten crab (Eriocheir sinensis) was first recorded from the Thames in 1935, but numbers having increased explosively since the early 1990s.

This species has subsequently been recorded from other UK rivers, such as the Tyne, and appears to be spreading rapidly.

The mitten crab damages riverbanks by burrowing into them, as well as posing a danger to native organisms by predating on them or out-competing them for resources.

According to Dr. Paul Clark of the Natural History Museum, the mitten crab appears in the Thames in large numbers, and it seems to be gradually dispersing westwards.

"It's eating everything in sight and the other problem is it burrows into soft banks," he said.

However, a recent report offers a solution at hand " the dinner table.

The Natural History Museum conducted a two-year pilot fishing programme investigating ways of reducing the population of mitten crabs in the Thames and concluded that harvesting the species for culinary use is a viable way of controlling the crabs (although this is not a novel solution as the mitten crab is considered a delicacy in Southeast and East Asia).

But the London Port Health Authority (LPHA), the food authority for the Thames, needed to ascertain if the crab was suitable for human consumption, so scientists from the LPHA, the Natural History Museum, the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), the Food Standards Agency (FSA) and the Central Science Laboratory have been assessing potential health risks.

They concluded that the levels of metal contaminants and hydrocarbons were too low to be of concern. However, the FSA has advised girls and women of child-bearing age against eating excessive amounts of mitten crab.