American signal crayfish

Signal crayfish were introduced as a food source in the late 1970s and 1980s but spread quickly across much of the UK.

Their small lobster-like appearance make crayfish easy to identify, however, care must be taken to distinguish between the invasive Signal crayfish and our native White-clawed crayfish.

What’s the problem?

• They out-compete native White-clawed crayfish; they spread crayfish plague (which decimates our native population), eat their food source and can actually eat smaller White-clawed crayfish.
• They burrow into riverbanks which eventually leads to the undermining and erosion.
• They predate on aquatic invertebrates and the eggs of native fish.
• Human transfer to unpopulated sites, although illegal, still continues.

If you do see a Signal crayfish in your local river, it could carry crayfish plague. Although not harmful to humans, the plague can be transported on clothing and unknowingly spread to uninfected areas.

Therefore, it is important to check, clean, and dry your clothing and equipment whenever you’ve been in the river and/or in contact with a Signal crayfish.

How you can help save our native White-clawed crayfish from the Signal crayfish

Clean your gear after being in the river.  Crayfish plague spores can be spread on damp equipment such as fishing tackle and canoes, so always clean and disinfect your equipment.

Don’t trap or remove any crayfish (whether alien or native). This can only be done with a special licence.

Spot one? Log it on INNS Mapper. Download this free app onto your phone and log your sighting so that we can determine whether they are close to/threaten our native populations. At the same, please notify the Environment Agency as well on 0800 807060.