A Chinese mitten crab seen on the shore of the river Thames in London
Mike Lane/imageBROKER/Shutterstock
People in the UK have been asked to report sightings of Chinese mitten crabs, a species of concern that is invading the country.
Chinese mitten crabs, scientifically known as Eriocheir sinensis, are native to East Asia and are named for their furry, brown, mitten-like claws. They have bodies that can be greenish-grey to dark brown in color and can grow up to 8 centimeters in length, with their legs twice as long.
Over the past century, these crabs have spread to various parts of the world, including Europe and North America, where they are considered invasive. They are typically found in freshwater habitats like rivers, canals, and estuaries.
Chinese mitten crabs can cause damage to the environment by burrowing into river beds, blocking waterways, and damaging fishing gear with their sharp claws. There are concerns that they may also consume fish eggs and compete with native species for resources.
The first sighting of Chinese mitten crabs in the UK was in 1935 in the river Thames, and they have since established themselves in waters across the country. There has been a recent increase in sightings of these crabs in waterways in Cambridgeshire.
The Natural History Museum has launched a citizen science initiative called “Mitten Crab Watch,” where members of the public can report their sightings of Chinese mitten crabs. The UK Department for Food, Agriculture and Rural Affairs is also encouraging people to report sightings, as this can help track the crab population and prevent the spread of their eggs.
“The numbers are increasing because they have a very unique life history. After migrating downstream, adult females can lay three batches of eggs,” explained Paul Clark, an expert at the Natural History Museum. Each batch can contain between 500,000 and 1 million eggs.
In an effort to control the growing population of Chinese mitten crabs in the UK, several organizations, including Lincolnshire Wildlife Trust, Welland and Deepings Internal Drainage Board, and the Natural History Museum, have installed the first permanent Chinese mitten crab trap in Pode Hole, Lincolnshire, in August.
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