Freshwater Habitats Trust is a UK charity with a mission to protect freshwater life for everyone to enjoy. As an evidence-based conservation charity, FHT promotes a strong science grounding in all their work. FHT approached us to help them carry out aquatic eDNA surveys around the River Ock catchment in Oxfordshire to collect baseline data on fish populations.

The NatureMetrics aquatic eDNA filter kits allowed FHT to quickly and efficiently complete the surveys, obtaining valuable data across 7 different sites to give a rapid fish eDNA baseline which will inform knowledge on freshwater biodiversity in traditionally understudied regions.

The Ock Arable project is engaging with farmers across the Ock catchment in partnership with Environment Agency to help tackle diffuse pollution and identify areas for potential wetland habitat improvement works and installation of Natural Flood Management measures.

We used eDNA kits at 7 locations in the Ock catchment to collect baseline data on fish assemblages in the project area. The NatureMetrics eDNA kits are easy to use in the field, and the team are very responsive and helpful throughout the process, from ordering kits to receiving survey results.

Adam Bows, Catchment Officer, Freshwater Habitats Trust

The Challenge

Bringing clarity with a clear baseline

Baseline ecological data is crucial in order to measure and monitor the impacts and successes of any implemented biodiversity management strategy.

Very little was known about the fish populations in the Ock catchment. FHT needed to rapidly collect information on fish assemblages from across the landscape so that measures to address pollution issues in the area could be undertaken and the results monitored over time.

Our role

Rapid surveying without invasive techniques

The Ock Arable Project and Freshwater Habitats Trust conducted an aquatic eDNA survey with NatureMetrics. As the aquatic eDNA kits are easy to use, no prior sampling experience was required so a project ecologist could collect samples easily and quickly whilst out on site.

Spread across the catchment are a range of springs, headwaters, ponds, small lakes, streams and rivers. The technique allowed for rapid surveys across a large landscape, including one sample from the river Ock and six of its small tributaries, meaning that no invasive methods were needed.

The Impact

An invaluable resource for measuring and protecting biodiversity

From seven aquatic eDNA samples, the highlights of the FHT baseline data included a total of 11 taxa detected, belonging to 6 orders, 7 families and 11 genera. The most commonly detected species was the three-spined stickleback (Gasterosteus aculeatus), a native species common in estuaries and coastal lagoons around Britain and Ireland.

The analysis also detected two species of note that can act as important indicators of freshwater ecosystem health:

  • The European bullhead (Cottus gobio), an IUCN Redlist and annex II SAC species

  • The brown trout (Salmo trutta), a popular commercial and angling favourite.


Freshwater Habitats Trust


River Ock, Oxfordshire

Sample Type

Aquatic eDNA


Freshwater aquatic

Group Targeted


11 taxa were uncovered using aquatic eDNA

Two species of note were detected that indicate freshwater ecosystem health

Detailed diversity patterns plus locational and frequency data across 7 sites

What next?

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What’s Next?

FHT now intend to carry out further validations of eDNA methods with side-by-side comparisons of eDNA metabarcoding and conventional fish survey methods to develop localised understanding of how this new technology compares.

For the Ock catchment, Adam and the team plan to follow this project with regular eDNA monitoring which could be extended to include more taxonomic groups such as amphibians and invertebrates.

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