Country diary: Nature red in tooth and – quite literally – claw | Charlie Elder

The river unwinds beneath overhanging trees, its broad back gently massaged by submerged knuckles of rock and trailing fingers of vegetation. Wading into the shallows, the conservationists James Maben and Charly Mead search amid tangles of tree roots and pull up short lengths of black plastic tubing bound together like oversized panpipes. They peer into the black cylinders, before emptying the silty contents into a bucket.

So far this morning the riverbed traps along this stretch of the River Culm have drawn a blank. But this time we are in luck. There in the bucket, resembling a little brown lobster, is a crayfish. More importantly, a white-clawed crayfish – and one that could help secure a future for this threatened freshwater species.

Pincering it between finger and thumb, James lifts it up to reveal its muddy bronze colouring and the pale undersides of its claws. “A signal crayfish would be far more feisty,” he tells me.

Signal crayfish – an invasive species of American origin – have had a devastating impact since arriving in the 1970s. Large and aggressive, they dominate river stretches and spread a disease that is deadly for Britain’s native white-clawed crayfish. Nature red in tooth and, quite literally, claw. In Devon, white-clawed crayfish could become extinct within a decade. The team I am accompanying are in a race against time.

Led by the Wildwood Trust, the Saving Devon’s Native Crayfish project involves catching white-clawed crayfish to breed in captivity, before rearing their young for release at safe “ark” sites. But this well-camouflaged and largely nocturnal species is not easy to find. The plastic tube traps deployed under licence provide snug underwater hidey‑holes, and the hope is that one or two are lurking within them when lifted out.

Fortunately, after the initial catch, other traps along a mile of river also prove fruitful. In all, half a dozen white-clawed crayfish are collected – each individual boosting the breeding project’s chances of success.

This is my first encounter with these secretive and endearing creatures. Their precipitous decline within UK rivers has taken place out of sight, but fortunately not out of mind among those striving to ensure they have a future.

• Country diary is on Twitter at @gdncountrydiary

• Under the Changing Skies: The Best of the Guardian’s Country Diary, 2018-2024 (Guardian Faber) is published on 26 September; pre-order now at the guardianbookshop.com and get a 20% discount