Bid to halt crays' reign of terror

Norfolk Wildlife Trust has welcomed plans to tackle the threat to Britain's wildlife from non-native plants and animals.The new measures announced by the Department for Environment, Food and Rural Affairs (Defra) yesterday aim to stop the spread of foreign species, like the North American signal crayfish, and help protect our native ones.

Norfolk Wildlife Trust has welcomed plans to tackle the threat to Britain's wildlife from non-native plants and animals.

The new measures announced by the Department for Environment, Food and Rural Affairs (Defra) yesterday aim to stop the spread of foreign species, like the North American signal crayfish, and help protect our native ones.

Experts said last night that non-native plants like the Australian swamp weed are also threatening wildlife in the River Wensum.

The government's plans include identifying potential threats earlier, introducing a rapid response system when invasive species are first detected and educating people on the problem.


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Defra minister Jeff Rooker said: “The introduction of species over thousands of years has shaped British wildlife and the countryside that we love. But non-native species that are invasive can have a serious impact on native wildlife and are estimated to cost the British economy at least £2bn a year.”

Brendan Joyce, Norfolk Wildlife Trust's director, said the trust was looking forward to working with Defra to tackle the problem in this county.

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He said: “We very much welcome action on this and we will be happy to do our bit in terms of raising awareness through our own membership.”

Native white-claw crayfish are quickly disappearing from Norfolk's rivers and streams because they cannot compete with the larger North American signal crayfish for food and habitat.

It is feared they will suffer the same fate as red squirrels, whose numbers have dwindled since the introduction of grey squirrels in the 19th century.

Signal crayfish can also carry a disease known as crayfish plague which is deadly to the white claw species.

They got into Britain's waterways after escaping from farms where they were bred as food.

Mr Joyce said plants like the Himalayan balsam and Australian swamp weed were threatening fish, plants and invertebrates in the River Wensum.

He said: “The Australian swamp weed is particularly nasty. It forms a blanket over the surface of the water, smothering everything underneath it so it dies.”

Non-native plants are often used in garden ponds. Mr Joyce said: “They can spread by spores or people just being careless.

“Our advice is for people to use native species for their ponds and if they are clearing out non-native species they should burn it rather than dumping it on a pile outside their garden.”

The Australian swamp weed was brought to Britain from Tasmania to be sold as an oxygenating plant in garden centres. It has light-green leaves, a yellow-green stem and small white flowers in the summer.

The Himalayan balsam can grow up to 2m high and has pink or purple helmet-shaped flowers. It was first introduced as a greenhouse plant in the 19th century.

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