Are Chinese mitten crabs edible? Arthropods invading and spreading across UK

Chinese mitten crabs have been spotted crawling around in the waterways of the United Kingdom. These crabs first appeared in the UK in 1935. Recently, they have been seen around London and Cambridgeshire, at a park in the southwest, at a dyke in Whittlesey, and in a park in Peterborough.

As per National World, the Chinese mitten crabs are edible, however, they can carry health risks due to the potential accumulation of pollutants. The crabs are a delicacy in China and are used in many dishes, such as crab soup, dumplings, or stir-fries.

As per BBC, the first permanent Chinese mitten crab trap has been invented and installed at Pode Hole in Lincolnshire to counteract the invasion of the species.

---

Invasion of Chinese mitten crabs explored

A researcher named Dr. Paul Clark from the Department of Life Sciences at the Natural History Museum has worked with Chinese mitten crabs since 1976 after he was asked to retrieve the second mitten crab found in Britain.

The crabs are thought to have come from eastern China to Europe and North America in ships through the sediment found on the bottom of ballast tanks, as per BBC. The Chinese mitten crabs are named as such because of their distinctive appearance, with a furry, or "mitten-like," patch of setae (hair) on their claws.

According to New Scientist, they are edible and are a delicacy in China. People are advised to ensure that the crabs are harvested from clean and uncontaminated waters, as they may carry a potential accumulation of pollutants.

According to The Department for Environment, Food and Rural Affairs (Defra), "In the UK, there is no legal fishery for the species, if a Chinese mitten crab is caught as a by-catch, they cannot be sold live for human consumption."

Dr. Paul Clark stated that in each spawning, the number of eggs produced can range from 500,000 to one million, as per BBC. He added:

"Numbers are rising because they have a very unusual life history. After the migration downstream, adult females may be able to produce three spawnings of eggs."

All the larvae might not reach the juvenile crab state, but according to the researcher, once a species gets established, it gets very difficult to remove them.

---

The Chinese mitten crabs trap

At Pode Hole in Lincolnshire, the first permanent Chinese mitten crab trap was installed on August 31, 2023. The collaboration was between Lincolnshire Wildlife Trust, the Welland and Deepings Internal Drainage Board, and the Natural History Museum.

The Welland Board donated around £8,000, and Mick Henfrey, who is employed by the Welland and Deepings Internal Drainage Board, made the trap. It is built like a letterbox that traps the mitten crabs and keeps them inside until researchers extract them for analysis.

As per The Independent, these forms of crabs are getting invasive and can weaken riverbanks and structures. It may lead to erosion and potential damage to infrastructure like levees.

The competition for food can disrupt local ecosystems and threaten the survival of native species in the United Kingdom. The crabs are stronger than some native species, and they compete for food resources and habitat, potentially winning and displacing native aquatic species, as per BBC.

If someone catches Chinese mitten crabs, they are obligated to report the arthropod sighting to the Environment Agency or a similar environmental agency, which is responsible for managing invasive species and water quality in their area.

A snip from the species may cause some discomfort and a minor injury, however, there have been no reports of serious physical harm from the species yet.