White-clawed Crayfish now ‘endangered’

The white-clawed Crayfish has now been upgraded to ‘Endangered’ on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

The White-clawed crayfish can grow up to 12cm in length. Pic Bristol Zoo Gardens

The White-clawed crayfish can grow up to 12cm in length. Pic Bristol Zoo Gardens

Experts warn the species could become extinct from the UK within the next 30 years; it is currently a protected species.

The upgraded status from ‘Vulnerable’ to ‘Endangered’ on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species follows a Sampled Red List Index (SRLI) assessment by the Zoological Society of London (ZSL).  The ranking gives an indication of how likely a species is to becoming extinct.

The White-clawed Crayfish (Austropotamobius pallipes) is the only species of crayfish native to the UK.

It can grow up to 12cm in length and live for 7 to 12 years in the wild.

They can often be found in small streams, rivers, lakes, reservoirs and old quarries. They prefer slightly alkaline well oxygenated water with only a small amount of sediment.

The change in status of white-clawed crayfish will help stress the need for conservation strategies
Eve Leegwater, Environment Agency

Eve Leegwater, Technical Biodiversity Officer at the Environment Agency, said: “‘It is important to base conservation efforts on scientific research and the IUCN Red List has become an increasingly important tool to guide government and scientific institutes towards the conservation and legislation of species and habitats at risk of extinction.”

She added: “The change in status of White-clawed Crayfish will help stress the need for conservation strategies to be implemented to aid this valuable species.”

Strongholds for the white-clawed crayfish

Throughout the country a number of organisations are mobilising in an effort to protect the few remaining animals.

The South West Crayfish Project is currently running the largest strategic translocation in the UK to date, re-homing at-risk populations of White-clawed Crayfish to new safe sites.

In addition, a breeding programme for the crayfish is being developed at Bristol Zoo Gardens – the sister organisation to the Bristol Conservation and Science Foundation (BCSF).

Double threat

Up to 70% of White-clawed Crayfish have between lost from the south west of England and some parts of the UK have lost their entire populations.

There is currently no effective way to eradicate non-native crayfish species, or the crayfish plague.
Maddy Rees, BCSF

This is predominantly due to the crayfish plague, called aphanomyces. This is a fungus-like disease which is harmless to people and most animals, but lethal to White-clawed Crayfish.

A second threat comes from the introduction of non-native species of crayfish, especially the American signal crayfish.

Precautions to help stop contamination

Maddy Rees, UK Conservation Officer for the Bristol Conservation and Science Foundation, said: “Although research is being undertaken, there is currently no effective way to eradicate non-native crayfish species, or the crayfish plague. However, there are some simple, precautionary steps the public can take to help prevent the spread of the crayfish plague.

White-clawed crayfish Pic Bristol Zoo Gardens

White-clawed crayfish Pic Bristol Zoo Gardens

The plague can be carried on anything that gets wet in infected water, so we are urging people to wash, dry and, if possible, disinfect footwear, fishing tackle, nets and other equipment that gets damp in our rivers and lakes.

Never trap for any species of crayfish without a trapping licence, as it is illegal, and finally, never move wild fish between waterways, always use a reputable stockist.”

In the North of England scientists hope that the native crayfish can find safe-haven in the relative safety of the waterways of Cumbria.

Paul Bradley who has been studying the native White-clawed Crayfish and the plague for over 10 years  said  “Cumbria supports possibly the best White-clawed Crayfish population in Europe. They are therefore very vulnerable to the plague and a single incident of the plague could devastate the Cumbrian population”.

White-clawed Crayfish conference

The survival of white-clawed crayfish will be the focus of a conference held at Bristol Zoo Gardens during November 2010.

The event, called ‘Species survival: Securing White-clawed Crayfish in a changing environment’ will take place on November 16 and 17 2010.

It will include a range of lectures from speakers from across Europe, and presentations from experts in the field of UK crayfish conservation.

To find out more, or to register to attend, please visit the ‘what’s on’ pages at www.bristolzoo.org.uk.

Further Crayfish information

For more information about the South West Crayfish Project, please visit www.bcsf.org.uk/about/conservation/project.

Guidance on works affecting the White-clawed Crayfish – Natural England

The life cycle of the freshwater invertebrate –  Eden Rivers Trust

Creating an ARK site for native Crayfish protection


The public are being reminded that it is illegal to disturb the protected White-clawed Crayfish without a licence and heavy fines may be imposed.

For more information on how to identify the differences between the native white-clawed crayfish and the invasive American signal crayfish, visit  the South Cumbria rivers Trust website – www.scrt.co.uk/cfinns.

You may also be interested in:

%d bloggers like this: