Crayfish

Unfortunately this good news does not apply to the one species native to the British Isles. Our resident white-clawed crayfish has actually suffered depleting numbers over the last 30 years, and it is now a protected species.

Most people would be able to identify a crayfish, thanks to their close resemblance to the familiar lobster. However, their nocturnal lifestyle and frequent habit of hiding in underwater crevices mean that crayfish are not often sighted - away from the dinner plate that is. Left alone, these small scavengers will thrive in any aquatic habitat, be it freshwater stream, canal, river or quarry pool. They like alkaline conditions with plenty of protective shelter such as rocks, drystone washwalls, reedy vegetation or tree roots.

In recent years, our native population has been threatened by the arrival - and spread - of the signal crayfish. This larger species was brought here from the USA to stock crayfish farms and meet growing culinary demand for fashionable seafood dishes. However, the docile white-clawed crayfish is simply no match for its beefy American cousin when it comes to competition over food and territory and sadly, the alien species is now top dog in many of our waterways.

Take part in British Waterways' 2008 National Wildlife Survey