The Environment Agency is carrying out a series of summer surveys to try to identify the cause of unusual symptoms in an endangered native species.
Last autumn around 100 native white clawed crayfish were found dead in the River Wansbeck catchment in Northumberland.
The subsequent investigation determined crayfish displaying similar symptoms - unusual orange patches on their shell - were widespread across the Wansbeck catchment as well as areas of the neighbouring rivers Tyne and Blyth catchments.
Now the Environment Agency is carrying out surveys across Northumberland and the North East through the summer to determine current populations of the native species.
The surveys will also be identifying locations where crayfish are displaying the unusual symptoms.
Intensive surveys on the Hart Burn, where the initial deaths were reported, as well as at some other sites, will help the Environment Agency understand the mortality rates in the population.
Working closely with experts
The team is working with both the Centre for Environment, Fisheries and Aquaculture Science (Cefas) and experts at Teesside University in efforts to understand more about the situation.
Sarah Jennings, Area Environment Manager at the Environment Agency said:
After a pause during winter and spring while the river levels were high we are now back out at rivers right across the North East to carry out widespread crayfish surveys.
We are working closely with experts at Cefas and Teesside University on sampling and analysis in efforts to understand more about what is happening to this important species.
There's a lot we still don't know but we hope this new work sheds some light as we continue efforts to safeguard the future of the white clawed crayfish.
Early surveys indicate that healthy populations of the native white clawed crayfish still remain in the North East - including in the Wansbeck catchment - but symptoms persist in some areas.
Surveys also show populations of the invasive American signal crayfish are also affected by the same symptoms.
Potential novel pathogens
Dr Jamie Bojko, Associate Professor in Disease Ecology (Research and Innovation), Teesside University, said:
We are applying metagenomic and metatranscriptomic methods, in combination with histology, to uncover potential novel pathogens that may be the cause of the shell abnormalities seen in the white claw population.
At the end of September last year, it was discovered that around 100 of the endangered native species had been found dead in the River Wansbeck catchment, one of the last remaining strongholds of the species.
Testing carried out by Cefas returned negative results for the listed disease white spot syndrome virus, in addition to Bunya-like brown spot virus, crayfish plague, and no evidence for any significant bacterial infection was identified.
The Environment Agency continues to be supported by the Northumberland Crayfish Partnership, which as well as the National Trust and Zoo, also includes Northumberland Rivers Trust and Northumberland Wildlife Trust.
The public and especially river users are being urged to follow Check, Clean, Dry advice to prevent the spread of symptoms:
- Check clothing and equipment for mud, aquatic animals or plant material. Remove anything found and leave it at the site.
- Clean everything thoroughly as soon as possible, paying attention to areas that are damp or hard to access and using hot water if possible.
- Dry for at least 48 hours, or if this is not possible use a suitable disinfectant before using elsewhere.
