Erika Pheonix, who is the Catchment Partnership Officer at Don Catchment Rivers Trust, recently visited the CRT’s Margaret Wood in Yorkshire to survey for white-clawed crayfish, England’s only native crayfish species.

The Don Catchment Rivers Trust has been working with Yorkshire Wildlife Trust in the Upper Dearne Catchment to identify sites where white-clawed crayfish (Austropotamobius pallipes) may be, as part of a broader initiative to protect and understand their remaining strongholds in Yorkshire. Their work has included surveying sites where remnant populations of this native species might still exist – it was hoped that Clough Dyke, a watercourse that runs through this pristine woodland, could be one of them.

White-clawed crayfish are primarily nocturnal, emerging at night to forage while spending the daytime hidden under rocks and boulders, woody debris or within the crevices of riverbanks. They require quality habitat to support healthy populations, which includes access to suitable refuges, a reliable food supply (such as leaf litter and aquatic macrophytes) and good water quality.

“Unfortunately, over the past few decades, white-clawed crayfish populations have suffered a dramatic decline. This has been driven by a combination of habitat loss, pollution and competition from invasive species like the signal crayfish,” explained Erika.

“These outcompete white-clawed crayfish for food and shelter and carry a fungal-like disease known as 'crayfish plague' which is lethal to the native species. As a result, the white-clawed crayfish is now classified as Endangered by the International union for conservation of nature (IUCN).”

Yorkshire Wildlife Trust host the Yorkshire Crayfish Forum, which is made up of various organisations, all with a passion to protect the remaining white-clawed crayfish populations in Yorkshire. The forum also helps to facilitate the coordination of crayfish efforts across the county, promoting communication, collaboration and partnership.

Recent surveying efforts have focused on the Cawthorne Dyke sub-catchment, a smaller tributary within the Upper Dearne, where white-clawed crayfish have previously been recorded.

Erika and the CRT’s Head of Conservation, Helena Darragh, conducted a licensed hand-survey of the Clough Dyke at Margaret Wood. The survey involved carefully searching the stream by hand, focusing on shallow, clear, slow-moving sections of water.

“We concentrated on areas with natural refuges such as submerged rocks and boulders, tree roots and woody debris,” revealed Erika. “Walking slowly upstream through the woodland, we carefully lifted rocks and debris within the channel inspecting each one for any signs of crayfish.”

“Unfortunately, we didn’t find any white-clawed crayfish during the survey or any invasive crayfish species either. While it was disappointing not to make a sighting, the absence of invasive species is still a positive sign. Our search will continue in other parts of the catchment, in the hope of locating remaining populations and building a clearer picture of the species' distribution in the local catchment.

You can see the distribution of Crayfish on the Yorkshire Crayfish Forum map here.