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Invasive Signal Crayfish Threaten Native White-Clawed Crayfish at Syston

We bring you some sobering news from the Upper Witham at Syston that has left us deeply saddened. The invasive signal crayfish (Pacifastacus leniusculus), known for their aggressive nature, rapid breeding, and carrying the deadly ‘crayfish plague,’ have been discovered in this delicate ecosystem, raising concerns for our beloved native white-clawed crayfish (Austropotamobius pallipes).

The Threat to Native White-Clawed Crayfish:

The arrival of signal crayfish in the Upper Witham poses a significant threat to our native white-clawed crayfish population. Unlike their native counterparts, signal crayfish are known for their aggressive behaviour, and they reproduce at a startling pace, quickly outcompeting the natives for resources.

What’s even more alarming is that signal crayfish can carry the dreaded ‘crayfish plague,’ a highly contagious disease that is lethal to our native crayfish. Once infected, native crayfish populations experience devastating declines, which can have cascading effects on the entire aquatic ecosystem.

Furthermore, signal crayfish are notorious for their burrowing habits. They dig into the riverbanks, causing extensive damage that not only destabilises the banks but can also lead to erosion, impacting the overall health of the waterway and increasing flood risk.

Signal crayfish were first introduced into the UK in the 1970’s, intended to be farmed for food. They quickly escaped the fisheries and swiftly spread across watercourses and land, where they began to outcompete the native white-clawed crayfish for both food resources and habitat.

What Can We Do to Help?

In the face of this disheartening news, it’s imperative that we take action to protect our native crayfish. We have a shared responsibility to minimise the spread of invasive species such as the signal crayfish.

One simple and effective way to contribute to the conservation effort is by following the Check, Clean, Dry protocol:

Check: Before leaving the water, carefully inspect your equipment and gear, such as fishing gear, boats, and waders. Look for any signs of invasive species, like signal crayfish.

Clean: Thoroughly clean and disinfect your equipment. This step is crucial in eliminating any potential hitchhikers that could be lurking on your gear.

Dry: Make sure your equipment is completely dry before using it in another waterway. Many invasive species, including crayfish, can survive for some time in damp conditions, so drying your equipment is a critical final step.

For more information on how to implement Check, Clean, Dry and other ways you can contribute to the conservation effort, please visit

Let’s work together to safeguard our natural treasures and hope for a brighter future for our native white-clawed crayfish.