The white-clawed crayfish population will be caught by hand and moved from Sheffield’s Porter Brook, which carries one of the most threatened populations in the Yorkshire region, to a tributary further up in the hills, above a reservoir.

There has already been an outbreak of crayfish plague in the downstream reaches of Porter Brook, and the invasive signal crayfish are advancing upstream. The new location will be kept secret.

The reservoir will act as a barrier, halting the upstream spread of the alien signal crayfish and the plague it carries, and hopefully giving the white-clawed crayfish a safe haven to help it survive.

Ian Marshall, a biodiversity officer for the Environment Agency, said:

“The new home for the white-clawed crayfish will be what we call an ‘ark site’ – a  place which is physically and biologically remote, giving the best protection for our native crayfish from the crayfish plague which has decimated them, and the invasive crayfish itself.

Once at this secure site the native population should be able to settle and reproduce safely, without the problems caused by the signal crayfish. The new location should also have less pollution, another factor in the decline of the white-clawed crayfish.”