There has been an increasing concern about the population growth of Chinese mitten crabs in the UK, and people have been asked to report sightings of these invasive species.
Chinese mitten crabs, scientifically known as Eriocheir sinensis, are native to East Asia and are named for their furry, brown, mitten-like claws. They usually grow to about 8 centimeters in length, with their legs extending to twice that length. 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.
This invasive species can cause significant damage to the environment by burrowing into river beds, blocking waterways, and damaging fishing gear with their sharp claws. There are also concerns that they could consume fish eggs and outcompete native species for resources. The Chinese mitten crab was first spotted in the UK in 1935 in the River Thames and has since become established in waters throughout the country, with recent sightings in Cambridgeshire.
To address the rising population of these crabs, the Natural History Museum in the UK has launched the “Mitten Crab Watch” initiative, encouraging members of the public to report their sightings. The UK Department for Food, Agriculture and Rural Affairs is also urging people to report sightings to track the crab population and prevent the spread of their eggs.
The population of Chinese mitten crabs is growing rapidly due to their unique life history. Adult females can produce multiple spawnings of eggs, with each spawning yielding between 500,000 and 1 million eggs. To control their population in the UK, the 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.
Are Chinese mitten crabs edible?
Chinese mitten crabs are indeed edible, and in China, they are considered a seasonal delicacy, especially in the autumn. They are commonly steamed whole and served with vinegar. The prices for these crabs can reach 2700 yuan (£300) for a box of eight crabs. The crab legs are known for their pale, silken flesh, while the shells contain the prized golden semen of the males and the bright orange roe of the females.
Although there have been concerns about the possible presence of lung fluke parasites in these crabs, a study conducted in the Thames estuary found no evidence of these parasites. However, high levels of Vibrio parahaemolyticus bacteria were detected in Thames crabs, which could pose a health risk if consumed raw or lightly cooked.
Chinese mitten crabs can also accumulate pollutants such as dioxins and polychlorinated biphenyls (PCBs) in their bodies. A report by the Natural History Museum mentioned that while excessive consumption should be avoided, the harvesting of mitten crabs from the Thames for culinary purposes does not need to be discouraged, especially considering the potential benefits to local fishermen.
Overall, the invasion of Chinese mitten crabs in the UK is a cause for concern due to their negative impact on the environment, but they also present an opportunity for individuals to enjoy a delicious delicacy when prepared and consumed safely.
