Call to help to tackle spread of invasive Chinese mitten crab in Wales

As Invasive Species Week (20th – 26th May) kicks off, Natural Resources Wales (NRW) is urging people across the nation to help stop the spread of the Chinese mitten crab, the only crab species found in UK freshwaters.

Already established in the Dee estuary, the Chinese mitten crab, an invasive non-native species (INNS), has now been confirmed in the Conwy estuary. Rare sightings have also been recorded in the Severn estuary. NRW encourages the public to record any sightings on the iRecord app or online to better understand the impact and spread of this invasive species.

The Chinese mitten crab poses significant threats to biodiversity. They are known to consume rare salmon eggs, large quantities of mussels, and extensive river vegetation, which can cause major damage to river courses. They also carry diseases such as lung fluke and crayfish plague, threatening native species like the protected white-clawed crayfish. Their burrowing activities further damage flood defenses.

Jennie Jones, Specialist Advisor for Invasive Non-Native Species at NRW, emphasized the importance of public involvement: “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.”

Jennie highlighted the need for biosecurity measures, public awareness, and community action: “These types of invasive non-native species, like the Chinese mitten crab, outcompete some of our native biodiversity and cause damage to the environment.”

“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.”

Invasive non-native species are one of the top threats to global biodiversity, contributing to 86% of extinctions on islands.

The issue costs Great Britain’s economy over £2 billion annually and can even harm human health.

The natural world is already under pressure from climate change and habitat destruction; invasive species further reduce the resilience of native wildlife.

Once introduced, managing INNS, particularly in marine environments, is challenging.

Early detection and rapid response are crucial to prevent their establishment and minimize their negative impacts.

To help stop the spread of the Chinese mitten crab and other INNS, NRW advises the public to take three simple actions:

1. Ensure you do not accidentally move this species to a new area by checking, cleaning, and drying any equipment, clothing, or shoes before traveling to a new site.
2. Learn how to identify the mitten crab and stay vigilant.
3. Record any mitten crab sightings via iRecord.