Breeding programme boosts endangered crayfish species

A breeding programme has boosted the numbers of an endangered species of British crayfish. The white-clawed crayfish is threatened by a deadly "crayfish plague" and competition from a brash American cousin that was introduced to the country in the late 1970s. The conservation project, launched in 2003 in the Yorkshire Dales, has produced 300 juveniles this year - making it the UK's most successful breeding programme for the native species.

The white-clawed crayfish (Austropotamobius pallipes) was once common in upland rivers and streams, favouring hard-water areas in particular. But its numbers have been devastated by a virulent plague caused by a fungus that was almost certainly brought to this country by the North American signal crayfish - a species that has been farmed in the UK for the seafood trade since the late 1970s. Now the International Union for the Conservation of Nature's Red List of endangered species rates the native white-clawed crayfish as vulnerable to extinction - just two categories away from being critically endangered.

The threat from the larger and more aggressive North American signal crayfish (Pacifastacus leniusculus) is particularly acute because, apart from spreading disease, it is able to breed faster and preys on the smaller native species. Crayfish plague has taken hold quickly because it can be spread by water, fish or equipment that has been in contact with the signal crayfish. In Northern Ireland, where there are no crayfish farms, the crayfish plague is unknown.

The Yorkshire project, run by Natural England and the Environment Agency, began by attempting to ringfence populations of the British crayfish. It has now moved on to developing techniques for captive breeding and rearing that allow more than 60% of offspring to survive - many more than would reach breeding age in the wild.

"We are at a critical stage in protecting our remaining native crayfish populations and our work in the Yorkshire Dales is at the forefront of conserving this endangered species. It has required a lot of hard work but the results demonstrate just how successful we have been in rearing native white-clawed crayfish. We now need to build on this success,"  said Neil Handy, fisheries officer with the Environment Agency, who is responsible for managing the facility.

"The news that white-clawed crayfish are breeding in increasing numbers in the Yorkshire Dales is extremely encouraging and shows that targeted conservation work can make a real impact. The species has been all but wiped out following the introduction of its American cousin, but the success of this project gives grounds for hoping that extinction is by no means inevitable,"  said Dr Helen Phillips, the chief executive of Natural England.