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Exploring Eden
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Exploring Eden

Big results from tiny DNA

29/05/2026 3 min read

 – using science to search for Eden’s endangered species

A major environmental DNA (eDNA) survey led by river conservation charity, Eden Rivers Trust (ERT) has provided new insights into the distribution of endangered native species and an invasive predator across the Upper Eden catchment within the North Pennines National Landscape.

Two men are in outdoors clothes and waders. They are wearing blue latex gloves. One has a syringe in his hand and the other a clear plastic bag containing water and a vial.
A man in waders is in bending over in a beck to collect water for eDNA sampling

What is eDNA sampling?

The project used eDNA sampling to detect the presence of water vole, white-clawed crayfish, and American mink across a wide network of rivers and streams—offering a snapshot of biodiversity in this area. 

Environmental DNA sampling is a relatively new tool that allows scientists to detect species by analysing genetic material in water, such as fragments of fur, poo and blood, providing a faster and less invasive alternative to traditional surveys. 

Stephen Henderson, ERT’s Conservation Manager: Species and Habitats explains the value of this survey:

“Being able to utilise the latest sampling techniques has been invaluable, and we are grateful for the support from the North Pennines National Landscape team through Defra's Farming in Protected Landscapes programme  to make this project happen. 

“While the technique has some limitations, it has demonstrated its value for a smaller charity such as ourselves as an efficient tool for large-scale biodiversity monitoring and conservation planning, particularly in the wild and remote becks on the fellside. As a result, we’ve been able to confirm anecdotal reports of two of our rarest and most threatened native species, alongside the presence of a key invasive predator.”

Key Findings

  • 99 water samples were collected from 19 watercourses, covering approximately 66 km of habitat.
  • White-clawed crayfish were detected at two locations, reaffirming their  continued presence in these small becks, although none were recorded in three becks where previously there were reported populations, requiring further investigation.
  • Water vole, an endangered species in the UK, was detected at five watercourses, including some previously unrecorded locations. On the nine watercourses where water voles had previously been recorded but eDNA was not found on this occasion, six tested positive for mink eDNA.
  • American mink, a non-native, invasive predator posing a serious threat to water voles and other native wildlife, was detected at nine watercourses, prompting immediate action with nine new mink traps deployed.

Overall, 27% of samples were positive for at least one target species, with detections recorded across 63% of surveyed watercourses. 

Read the full report - eDNA surveying in the North Pennines National Landscape

With such a wide area to survey, Stephen explains how the trust approached this mammoth task:

“Volunteers have been central to the success of this work. Following training in eDNA surveying techniques, ten volunteers contributed 91 hours to sample collection, enabling us to cover a wider and more statistically robust area.

“With both staff and volunteers now trained in this approach, we see potential to carry out further eDNA surveys in other hard-to-reach parts of the catchment. This will help us build a clearer picture of the health of some of Eden’s smallest and most vulnerable species and target our conservation efforts most effectively .”

Supporting Conservation Action

The findings are already driving conservation action on the ground. Identifying the presence of new populations of water voles and white-clawed crayfish has helped to pinpoint where follow-up physical surveys should be conducted to understand more about the populations suggested by the data and inform future conservation efforts here.

Evidence of mink presence has led to expanded trapping efforts, with multiple landowners agreeing to deploy traps across the area – helping the trust realise their goal of a mink-free Cumbria.

Whilst out in the field, engaging with farmers and land managers has opened up more opportunities to work together, making habitat improvements that create better conditions for water voles and crayfish to thrive in. 

By aligning funding from Defra and its agencies, the trust has supported local farmers to install fencing to create wider riparian buffer zones and install alternative livestock watering solutions. The photo above shows ERT staff with Chris Addy from the Environment Agency in the new buffer.

Tim Jacobs, Farming and Nature Officer at the North Pennines National Landscape said: 

“We are pleased to have been able to support this Eden Rivers Trust project which has provided a clearer picture of species presence across the Eden catchment’s becks. It has also been invaluable for working more closely with farmers, with a good number already taking action to help remove mink and to improve river bank habitats and water quality. 

"It is hoped that it will also help to inform their future farming and nature opportunities and ambitions.”

Made possible thanks to the North Pennines National Landscape team through Defra's Farming in Protected Landscapes programme.

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