White-Clawed Crayfish
The white-clawed crayfish is the only native species of freshwater crayfish in England. They are mainly found in rivers, reservoirs, and lakes. They are primarily nocturnal, hiding under stones or in banksides during the day.
Alexander Mustard / 2020
Threats:
Populations are now rapidly declining due to many factors including habitat loss, pollution, and the introduction of invasive crayfish species. This has led to white-clawed crayfish being classed as Endangered.
Legal status:
The white-clawed crayfish is protected under Schedule 5 of the Wildlife and Countryside Act (1981). This means it is illegal to harm, disturb and take (including picking up or handling) this species.
What
are Invasive Non-Native Species?
Some species have been introduced (deliberately or accidentally) by people and established outside of their native range. This has a detrimental impact on wildlife, habitats, and the economy.
These are Invasive
Non-Native Species (INNS)
They can displace native species, spread disease, decrease biodiversity and clog waterways. This adversely impacts recreation by affecting water quality, fishing and navigation.
1970s, after escaping from commercial fisheries, this INNS has had a devastating impact on white-clawed crayfish populations across England. Its larger size, more aggressive behaviour and ability to produce more young has enabled it to outcompete the native species for habitat and food.
inda Pinkin / 2020 VISION
This species also has a negative impact on river ecosystems. Heavy burrowing in banksides can increase sediment in the watercourse and lead to bank collapse.
The invaders are also causing the decline of other native freshwater species, including many fish, by competing for food and eating their eggs.
John Boulton
Crayfish Plague
Signal crayfish can carry an invisible killer - crayfish plague, a type of water mould that is deadly to whiteclawed crayfish.
Crayfish plague can also be accidentally moved between watercourses on clothing and equipment. Outbreaks of plague have been found in watercourses where no signal crayfish are present.
Obvious signs of crayfish plague include large number of dead whiteclawed crayfish in the watercourse and on banksides, and individuals appearing active during the daytime.
By following three simple steps after leaving the water, you can help stop the spread of invasive non-native species and disease, including crayfish plague.
CHECK your equipment, boat, and clothing after leaving the water for mud, aquatic animals and plant material. Remove anything you find and leave it at the site.
CLEAN everything thoroughly as soon as you can, paying attention to areas that are damp or hard to access. Use hot water if possible.
DRY everything for as long as you can before using elsewhere as some invasive plants and animals can survive for over two weeks in damp conditions.
Crayfish Trapping
Trapping invasive crayfish, such as signal crayfish, can be problematic for several reasons:
Accidental trapping of protected white-clawed crayfish.
Increases risk of spread of invasive crayfish and crayfish plague .
Not an effective method for control (removing larger crayfish via trapping can lead to a population boom).
Accidental trapping and killing of protected species such as water vole and otter.
Trapping any species of crayfish requires permission from the Environment Agency and Natural England, but permission may be denied.
Crayfish Dos
Practice ‘Check Clean Dry’ biosecurity to prevent the spread of crayfish plague and other INNS.
Leave all crayfish where you find them, regardless of species (it can be difficult to tell the difference between native and invasive crayfish).
Report illegal crayfish traps (no visible white EA tag) to the Environment Agency (0800 80 70 60).
Report crayfish sightings to the Environment Agency and online through iRecord (irecord.org.uk).
Crayfish Don’ts
Pick up any species of crayfish (unless authorised to do so).
Move crayfish to another watercourse.
Trap crayfish for consumption or control.
Use crayfish as bait.
North Yorkshire Crayfish Forum
North Yorkshire is a stronghold for the endangered white-clawed crayfish, but the population is under threat and could disappear completely if no action is taken.
The North Yorkshire Crayfish Forum, led by Yorkshire Wildlife Trust, is made up of various organisations including government agencies, national parks, conservation charities and private companies, all with a passion to protect the remaining white-clawed crayfish populations in North Yorkshire. The forum facilitates the coordination of crayfish efforts across the county, promoting communication, collaboration, and partnership.
Ones to watch…
Virile crayfish
There are a number of invasive crayfish species that are threatening to become established in England.
Here are the main species to watch out for: Narrow-clawed (Turkish) crayfish
Spiny- cheek crayfish
Virile crayfish
Red swamp crayfish
White river crayfish
Red claw crayfish
Red swamp crayfish
For further information visit nonnativespecies.org/non-nativespecies/information-portal
N ick Mott
Staffordshire Wildlife Trust
This pocket guide was produced in partnership between: With funding from: