Crayfish deaths in watercourses in our area, and increased biosecurity
The Environment Agency is investigating the deaths of our rare protected native white clawed Crayfish in three locations across the Severn and Wye river catchment. It is expected that the cause of this will be confirmed as Crayfish Plague which is very infectious for Crayfish.
White clawed Crayfish look like miniature lobsters, they hide away under rocks and logs during the day, and emerge during the night to eat. They are our largest freshwater invertebrate and the few remaining populations are very vulnerable to this disease and face local extinction. Crayfish Plague is a species specific disease and has no implications for human or other animal health. It is a water mold (fungus) that is carried mainly by American Signal Crayfish and it’s spores can be easily transported and transferred from infected waters by people and animals.
Dead white clawed Crayfish have been seen in the following catchments:
• Nailsworth Stream, Gloucestershire
• Dowles Brook, Wyre Forest
• The River Redlake, Shropshire
White Clawed Crayfish maybe infected, but apparently healthy, and continue to die for several weeks in these locations therefore an outbreak of Crayfish Plague can last for several weeks. The disease can be transferred to White Clawed Crayfish via water and mud on damp clothes, footwear, bike tyres, fishing or boating equipment or any machinery. The Crayfish Plague pathogens can live for 22 days on damp clothes or equipment.
We are asking the public to stay out of watercourses in these areas. If you are using equipment in any river, to stop the spread of the Plague, other infectious diseases or invasive species, please follow these steps:
• Clean off any mud or vegetation and remove any standing water.
• Either thoroughly dry the equipment, preferably in sunlight making sure all nooks and crannies are dry OR
• Treat with a disinfectant capable of killing fungal spores, such as Virkon, or an iodine based disinfectant
• If you or your dog goes into a stream, do not go into another stream on the same day.
The cheapest, safest and most effective way of disinfecting any equipment is to thoroughly dry it in sunlight for a minimum of 48 hours. It is essential that all mud and debris is removed first.
If this is not possible then the use of Virkon as a disinfectant is the next best alternative. Again it is essential that all mud and debris are removed first before applying Virkon. For boots it is best to use a boot dip if possible (step in tub) or to spray the whole of the boot liberally with Virkon. For other equipment (nets, sample cans, etc) it is recommended to immerse for 10-15 minutes in Virkon solution and then to rinse with clean water or leave to dry.
Virkon solution is best made up using Virkon (5mg) tablets, where one tablet is added to 500ml of water (2 to 1litre). This will then go pink and stay active for approximately 5 days. After this the pink colour will start to fade and the solution should be changed. Dispose of used solution safely (not surface water drain).
More information and resources can be found on the non-native species website: http://www.nonnativespecies.org/checkcleandry/
If you would like additional information about increasing biosecurity and targeting other vulnerable White Claw Crayfish populations please contact the Environment Agency at SHWGenquiries@environment-agency.gov.uk
The Environment Agency have temporarily suspended routine activities in these watercourses and are taking additional precautions in other catchments with native crayfish.
If you see dead Crayfish or an environmental incident please phone 0800 80 70 60.
Please do not handle or remove live or dead Crayfish. It is illegal to do this without a license.