Bristol Zoo Staff In a Rush to Relocate and Save Rare Crayfish

By Vanessa Hollier

Bristol, UK - A vital project to save the UK’s only native crayfish from extinction has begun in the south west.

The project sees the translocation of the white-clawed crayfish into safe havens in an attempt to halt the takeover by the aggressive, disease-carrying American signal crayfish.

The effort is being led by the Bristol Conservation and Science Foundation (BCSF) - a sister organisation to Bristol Zoo Gardens - in partnership with the Avon Wildlife Trust, natural England, the Environment Agency, Bristol Water and Buglife. 

The rare white-clawed crayfish is the UK’s largest freshwater invertebrate and plays a vital role in aquatic ecosystems. But the species faces extinction from UK waters within 30 years unless new populations can be created in safe, uncontaminated waters.

Jen Nightingale, the UK conservation officer for BCSF, explains: “White-clawed crayfish were abundant and easy to find until the American signal crayfish species was introduced to UK waters in recent years. The American species not only out-competes native crayfish for resources, it also carries a disease, the crayfish plague, which is fatal to UK crayfish. We now believe that three quarters of native crayfish populations in the Bristol Avon catchment area have been wiped out.”

Natural England has provided funding for the partner organisations to set up the South West White Clawed Crayfish Conservation Group to carry out the largest strategic translocation effort in the UK to date.

The first relocation day saw staff and volunteers from Bristol Zoo Gardens, the Avon Wildlife Trust and the Environment Agency move a number of crayfish from South Gloucestershire to two new ‘safe’ sites in Somerset. 

Jen Nightingale said: “The native crayfish population in our target area has been categorised as highly at risk of being infiltrated by American signal crayfish or crayfish plague, so we decided to catch enough individuals to form two new populations in designated safe sites, without impacting on the existing population.”

She added: “Both sites are isolated water bodies with little chance of being affected by American Signal crayfish. We want to keep these locations secret to prevent people visiting the areas and risk spreading crayfish plague – which can be carried on damp equipment and boots as well as in water. People who visit rivers, ponds and lakes can help prevent the spread of disease by washing and drying equipment after use. We’d also like to encourage people to report crayfish sightings - of any species - to the Environment Agency.”

Pete Sibley, from the Environment Agency, said: ‘It is hoped that by re-establishing the native species in an area free of the American crayfish will help it re-establish itself and increase in number. It was important not to harm the resident ecology when transferring the crayfish to new sites and exhaustive tests had been undertaken to assess the new habitat and ensure that there was a high water quality, tree cover with leaf litter, and rocks and boulders for refuge. This type of rescue mitigates the threat from signal crayfish by actively conserving natives through seeking out safe refuge sites. Efforts to eradicate American Signal Crayfish have to date proved unsuccessful.”

The crayfish had to be moved carefully in chilled containers to their new homes in Somerset and North Somerset where they were released. These populations will be monitored carefully, to determine whether the translocated crayfish are able to successfully form new, secure, populations for the future.

For more information about the Crayfish Conservation Group visit the Environment Agency website at www.environment-agency.gov.uk/homeandleisure and click on ‘fishing’.

For more information about Bristol Zoo Gardens and its conservation projects, visit www.bristolzoo.org.uk/about/conservation

Bristol Zoo Gardens

· Bristol Zoo Gardens is open from 9am every day except Christmas Day.

· The Zoo is an Education and Conservation Charity and relies on the income from visitors to support its work.

· The Zoo is involved with over one hundred co-ordinated breeding programmes for threatened wildlife species.

· It employs 140 full and part-time staff to care for the animals and run a successful visitor attraction to support its conservation and education work.

· Bristol Zoo Gardens supports – through finance and skill sharing - over 10 projects in the UK and abroad that conserve and protect some of the world’s most endangered species.

· Bristol Zoo Gardens is a member of the British and Irish Association of Zoos and Aquariums. BIAZA represents more than 90 member collections and promotes the values of good zoos and aquariums.

To view Bristol Zoo's web page on Zoo and Aquarium Visitor, go to: http://www.zandavisitor.com/forumtopicdetail-719-Bristol_Zoo_Gardens