Giant Chinese crabs invading North Wales waters

Kelly Williams & Steve Bagnall
·4-min read
The invaders are thought to have travelled from eastern China to Europe in sediment on the bottom of ships' ballast tanks
The invaders are thought to have travelled from eastern China to Europe in sediment on the bottom of ships' ballast tanks -Credit:Reddit


People are being urged to be vigilant for an invading army of giant Chinese mitten crabs spotted in North Wales waterways. With more than 800 sightings recorded in the UK, their presence has now been confirmed in the Dee, Conwy, and Severn estuaries in Wales.

The crabs – named because of their huge furry claws – are among the 100 worst invasive species according to Natural Resources Wales.

The environment organisation warned the creatures are eating the UK's native fauna and posing a threat to biodiversity and are urging members of the public to do their bit to protect it.

READ MORE: The North Wales beach pollution alerts after 'get out of sea' warning

READ MORE: Casualty taken to hospital after Gwynedd cliff fall sparks multi-rescue team response

the UK set up its first trap for the crabs at Pode Hole in Lincolnshire last year in a bid to snare the predators as they migrate downstream to mate, reports The Star.

The invaders are thought to have travelled from eastern China to Europe in sediment on the bottom of ships' ballast tanks either as tiny crabs or larvae.

The first one spotted in the UK was recorded at Lotts Road Power Station which used to generate electricity for the London Underground.

Females can carry from between 500,000 and a million eggs at one time. Experts said there are millions "eating us out of house and home" with native food being depleted and biodiversity "going down."

Mitten crabs grow to the size of a 10in dinner plate
Mitten crabs grow to the size of a 10in dinner plate -Credit:NRW

Mitten crabs grow to the size of a 10in dinner plate, damage fishing gear with their razor sharp claws and eat native species.

Researchers found they prey on salmon and trout eggs - species already under threat in the wild. They also feast on large quantities of mussels and so much river vegetation that they can cause major damage to river courses.

They can carry diseases such as lung fluke and crayfish plague, and will outcompete and predate on the protected, white-clawed crayfish, as well as damage flood assets by burrowing.

Adult Chinese mitten crab spend four to five years in freshwater and move down to estuaries to breed and spawn before they die. Their plankton develop in the estuary, and then juveniles move back upstream.

Jennie Jones, specialist advisor for invasive non-native species (INNS) at Natural Resources Wales said: “Protecting biodiversity is so vital in tackling the climate and nature emergencies. It is important to take action to tackle INNS that pose a threat to native wildlife.

“Most non-native species are harmless, but around 10-15% can become invasive and cause harm. These types of invasive non-native species, like the Chinese mitten crab, outcompete some of our native biodiversity and cause damage to the environment.

They pose a threat to biodiversity
They pose a threat to biodiversity -Credit:Getty images

"There are ways we can all help to prevent the spread of these species, including carrying out biosecurity, recording your sightings and joining a local action group. We really encourage people to get to know what these invasive species are, and record their sightings through the iRecord app or through its online space that collects information about where these non-native invasive species are being seen.”

Sign up now for the latest news on the North Wales Live Whatsapp community

Invasive non-native species are one of the top threats to global biodiversity; 86% of extinctions that have happened on islands were contributed to by invasive non-native species. It costs Great Britain’s economy over £2 billion a year to deal with the issue, and INNS can even harm human health.

To help stop the spread of the Chinese mitten crab and other INNS, there are three simple things people can do:

1. Ensure you do not accidently move this species to a new area by checking, cleaning and drying any equipment, clothing or shoes before travelling to a new site. Now is a critical time in the lifecycle of mitten crabs, there will be larva in the water column which cannot be seen but can cling to any equipment you might be using. It is especially important to check clean dry all your equipment at this time

2. Learn how to identify mitten crab and keep an eye out for this species

3. Record any mitten crab sightings via iRecord

See what's happening in your area:

  • Up next
  • Up next
  • Up next
  • Up next

Latest stories

  • Finally, an answer to a mystery surrounding these 1,000-year-old trees

    The mighty baobab has grown across mainland Africa, Madagascar and Australia for millions of years. But until now, scientists disputed where they came from.

  • 16 common plants you should NEVER grow in your garden

    From invasive weeds that can cause structural damage and cost thousands to irradicate, to pretty blooms harbouring poison inside their leaves or roots, these problematic plants could cause you a headache...

  • Crabs, cockatoos and ringtail possums: the wild things thriving in our cities

    From bees to burrowing owls, many species are adapting to urban environments and, with a little extra help from us, more could follow suit

  • UK weather: Hottest day of the year so far as temperatures hit 28.3C - but cold front on the way

    The UK has experienced the hottest day of the year so far. Temperatures hit 28.3C (82.9F) on Monday in Wisley, Surrey, after a four-day heat health alert came into effect. In London, the temperatures peaked at 27.4C (81.3F) in St James's Park while Aberdeenshire saw the mercury hit 26.9C (80.4F).

  • Watch: Rattlesnakes flee hail storm, return to sip melting ice

    Trail cameras captured the rarely observed phenomenon at a rattlesnake rookery Monday in Northern Colorado.

  • Top Climate Scientist Sums Up Second Donald Trump Term With 2 Chilling Words

    Michael E. Mann offered a terrifying analysis of what a second Trump administration would mean for both the American and global fight against climate change.

  • Wolf Shows Playful Interest in Grizzly Bear's Meal

    A wolf seemed super keen to get a piece of a bison carcass from a grizzly bear, footage by a nature photographer in Yellowstone National Park shows, but the bear seemed unimpressed by its antics as it bounced around.Trevor LaClair said he filmed the scene in April 2023, when the bear pulled the carcass from a frozen pond.“Two of the wolves approached the grizzly. One of the wolves got too close and the bear lunged at it as a warning. However, the wolf viewed it as an opportunity to potentially lure the bear away and began play bowing and bouncing around,” LaClair wrote on Instagram.“After a while, the grey wolf gave up and laid down nearby, waiting patiently for a piece of meat,” LaClair added. The grizzly eventually left and the wolves were able to get their turn.According to the National Wildlife Federation, a wolf will dance and bow if it is feeling playful. Credit: Trevor LaClair via Storyful

  • Green Party leader admits she has gas boiler, not heat pump

    The Green Party leader has admitted that she still has a gas boiler despite her party’s commitment to reach net zero by 2040.

  • Woman 'Seriously Injured' After Being Mauled by Wolves at Zoo in France

    A Paris woman was attacked by Arctic wolves while out for a run at the Thoiry ZooSafari in France and sustained bites to her neck, leg and back

  • The ‘world’s largest mammal migration’ happens here every year. War means no one knows about it

    New research shows that more than 5 million antelope cross South Sudan each year – blowing the world-famous Serengeti migration out of the water.

  • Residents of a small island off the coast of Panama evacuate as the sea level rises

    CNN’s Rafael Romo reports on island residents who are relocating, about the human impact of climate change.

  • Berlin Zoo Welcomes Newborn Giraffe

    A zoo in Berlin has welcomed the arrival of a baby Rothschild giraffe.Tierpark Berlin said the almost six-foot-tall newborn was “still a little wobbly on its feet, but nonetheless in great shape.”The baby giraffe was born to 10-year-old Amalka, the zoo said, her fourth calf in all. The new arrival brings to nine the total number of giraffes at the zoo.Rothschild giraffes are endangered, with only 1,400 remaining in the wild, the zoo said.The zoo’s mammal curator Maren Siebert said, “Rothschild giraffes are threatened in their native Kenya and Uganda, primarily by illegal hunting and the expansion of agriculture.”“The fragmentation and destruction of habitats has also led to the Rothschild giraffe being eradicated in almost its entire former range,” Siebert said. Credit: Tierpark Berlin via Storyful

  • New species of arachnid captured on video for first time

    The Associated Press has captured footage of a new species of arachnid on camera for the first time. Biologists in southern Spain discovered the new species - the first of its kind to be found in the country in 200 years. Gluvia brunnea belongs to the order solifugae and, although they are sometimes called camel spiders, they're actually a different creature altogether.

  • Critically endangered wildcat kittens born in Scottish national park

    Two wildcats released into a national park last year have given birth, marking a “major milestone” for wildcat recovery in Scotland, conservation experts have said. Nineteen wildcats bred in captivity were released into the Cairngorms National Park last June as part of efforts to save the species which in 2018 was deemed to be on the verge of extinction. The Saving Wildcats partnership, led by the Royal Zoological Society of Scotland, said that at least two of the females have now given birth in the wild.

  • Clean energy, fresh mussels: Scandinavia’s experiment to harvest seafood and wind power together

    Denmark is serving up a side of mussels alongside renewable power.

  • Nine tonnes of bird poo removed from landmark North East bridge

    Nine tonnes of bird muck removed from Tyne Bridge Nine tonnes of bird poo has been removed from the Tyne Bridge in the early stages of its huge restoration.

  • Highs of 31C forecast for coming week as temperatures continue to rise

    A yellow heat health alert has been issued by the UK Health Security Agency (UKHSA) and Met Office for most of England.

  • Wildcat kittens born outside captivity in Cairngorms a ‘major milestone’

    Adult cats were released into national park last year after British population had come close to extinction

  • Bear Inspects Truck Bed, Grabs Bag, and Leaves

    A curious bear was caught red-pawed helping itself from the back of a truck in Tennessee, not far from Gatlinburg where a theme park employee recently found herself face to face with a furry visitor.Keith Aldijaili told Storyful that he was used to seeing this particular bear near his rental cabins in Sevierville, alongside her several cubs.Aldijaili’s Ring camera recorded the moment the bear inspected the back of his truck for a while, before leaving with a white plastic bag. Credit: Keith Aldijaili via Storyful

  • Will climate change really lead to more immigration? Here's what the experts think

    All of the experts Euronews Green spoke to said the same thing: there is no empirical evidence to support the claim that climate change will lead to more international migration into Europe.