The heatwave hits its stride before breakfast, building to a dog day intensity that will relent only with the last red moments of the sunset. For the long hours between, an endless afternoon, the light ceases to move, training its intensity on the elderflower, oxeye daisies and buttercups of Wharfedale until their colours take on the bleach-brightness that signals high summer in England.
The weather brings people out of hibernation, and into encounters with unfamiliar forms of life. “Look at the size of that crayfish!” The woman paddling in the untypically warm river Wharfe near Appletreewick points near her feet, causing half a dozen swimmers to coalesce around the spectacle. Children express something between amazement and open-mouthed horror.
The crustacean is almost as long as a breadknife, a proper freshwater lobster, and compellingly grotesque. Its body is as dark as the river at its deepest, where the peat-stained water turns as black as molasses.
My friend reaches into the water to try to pick it up, but it shoots backward with startling speed, and he gingerly backs off. We track it across the riverbed before it slides into the shade of some rocks and dissolves back into the river’s darkness.
Its size would seem to suggest it was an introduced American signal crayfish, Pacifastacus leniusculus, as would the balance of probability. The native white-clawed crayfish, Austropotamobius pallipes, is thought to be all but wiped out in the Wharfe, having suffered the same fate as the species across England; a seemingly inexorable devastation by an infection to which the signals – voracious hunters that cannibalise their own young – are immune.
Only on rare days do we wade and swim en masse in the waters of rivers such as the Wharfe, so this aquatic extinction goes largely unseen and unnoticed. But a little way downstream from Appletreewick, someone has placed the recently severed head and claws of another signal, with its unnerving eyes and antennae still intact, on a fence post. This one was not fortunate when its moment in the limelight of human attention arrived.
