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27 Mar 2017

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

Posted in Latest news

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, the Wildfowl & Wetlands Trust (WWT) has joined other environmental organisations in 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 at WWT 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’.