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Ballast convention reduces mitten crab threat, but it’s not the end of the story

At the start of Invasive Species Week, environmental organisations have welcomed the Government’s commitment to tackle the risk posed by ships’ ballast water.

27 March 2017

The risk to UK wildlife from invasive Chinese mitten crabs will be significantly reduced once the Government follows through on its commitment to treat ballast water from ships coming into UK waters. However, environmental organisations are highlighting that invasive non-native wildlife can still enter the environment through other routes.

Ballast water is used to stabilise ships and in doing so it transports marine plants and animals around the world. Discharged ballast water is implicated in introducing many aquatic invasive species into the UK, including the Chinese mitten crab, which have the potential to wipe out native species.

The Chinese mitten crab population has increased rapidly in recent years. Significant populations now exist in the Thames and other rivers throughout England and Wales. As well as affecting native crayfish, they damage riverbeds and banks causing problems for freshwater fisheries.

Environmental organisations welcomed the news this week that the UK Government has committed to complying with The Ballast Water Management convention, which will require all ships involved in international trade to manage their ballast water to specified standards from September 2017.

Hannah Freeman, Government Affairs Officer, Wildfowl & Wetlands Trust said:
‘Transport and establishment of invasive species through ballast water plays a significant role in the health of our native aquatic species. The Ballast Water Management Convention is an important international tool to tackle a global problem. We welcome the Government’s intention to comply with and ratify the Convention. This is an important step to maintaining our status in Europe as frontrunners on action against invasive non-native species’.

Concern remains about other routes for invasive species to reach the UK environment. The trade in live crabs for restaurants is highlighted as a potential threat. Chinese Mitten Crabs are kept alive before consumption. As female crabs’ culinary value decreases during pregnancy, there is temptation for them to be released into nearby watercourses to be harvested later. Environmental organisations want to ensure that the EU Invasive Alien Species Regulation is brought into domestic law through the Great Repeal Bill in order to counter such threats.

Chair of Wildlife and Countryside Link’s Invasive Non-Native Species Group, Camilla Morrison-Bell said:
‘We know the number of invasive non-native species in England continues to increase and their arrival through ballast water is just one of the pathways into the country. We will continue to work with the Government to tackle invasive non-native species, through ensuring the EU Invasive Alien Species Regulation is brought into domestic law through the Great Repeal Bill and that the GB Non-Native Species Strategy continues to be implemented. Both contain important measures to prevent the arrival of invasive non-native species within England and the UK’.


This press release is supported by the following organisations:

Buglife, RSPB, WWT, Angling Trust, The Rivers Trust and the British Ecological Society

Notes to editors:

  1. Invasive Species Week runs from 27 March – 31 March 2017. The Great Britain Non-Native Species Secretariat and Defra launched the first Invasive Species Week in 2015. It brings together a range of organisations and individuals to raise awareness of invasive non-native species and the damage they can cause.
  2. Wildlife and Countryside Link (Link) brings together 46 voluntary organisations concerned with the conservation and protection of wildlife and the countryside. Our members practise and advocate environmentally sensitive land management, and encourage respect for and enjoyment of natural landscapes and features, the historic and marine environment and biodiversity. Taken together our members have the support of over 8 million people in the UK and manage over 750,000 hectares of land. Invasive species blogs can be viewed at:
  3. The EU Regulation (1143/2014) on invasive alien (non-native) species entered into force on 1 January 2015. The Regulation imposes restrictions on a list of species known as “species of Union concern”. These are species whose potential adverse impacts across the European Union are such that concerted action across Europe is required. This list is drawn up by the European Commission and managed with Member States using risk assessments and scientific evidence.
  4. Mitten Crab Recording Project -
  5. Free to use images of Chinese Mitten Crabs can be downloaded from the GB Non-Native Species Secretariat here
  6. For media enquiries or interview opportunities please contact: Mark Simpson, Wildfowl and Wetlands Trust,, 07825 890 590

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