Community Scientists Tracking the Elusive European Eel

This year, The eDNA Consultancy had the privilege of working alongside the North Kent Marshes Internal Drainage Board (NKMIDB), the Medway Swale Estuary Partnership (MSEP), and the Port of London Authority on a pioneering community-led project to map European eel presence (Anguilla anguilla) and highlight barriers to their migration.

Why Eel, and Why Here?

European eel numbers have plummeted by 95% in recent decades, driven by habitat loss, migration barriers, pollution, and illegal trade. The North Kent Marshes are a vital stopover for juvenile eel, or elvers, as they disperse upstream from the sea — but tidal outfalls, sluices, and culverts can stand in their way. Until now, there’s been little local data to show where eel are still managing to travel, and where connectivity has been lost.

Eel are ideal candidates for eDNA monitoring because of the high quantities of DNA they shed, leaving clear genetic traces in the water as they move. This makes them especially detectable even in low densities and in complex habitats like marsh drainage channels.

Bringing eDNA Into the Field

Our role was to provide the sampling kits and training, as well as to carry out the laboratory analysis. We used a European eel DNA assay developed by one of our own researchers at The eDNA Consultancy, optimised for sensitivity and specificity to this species. By detecting the genetic traces shed into the water, we could confirm eel presence without handling or disturbing them — an ideal approach for such an elusive species.

We delivered training supported by a step-by-step video guide, enabling volunteers to confidently collect and preserve water samples. Each sample was filtered on site, sealed, and sent to us for analysis. We then ran qPCR assays to detect eel DNA and confirmed a subset of positives with Sanger sequencing for added certainty.

photo by Marin Tulard

Community Science in Action

Despite a few logistical hurdles — from locked gates and reed-choked ditches to silty water that clogged filters — the volunteers and project partners did an outstanding job. 40 samples were collected from across the Medway, with eel DNA detected in 25. That’s a strong indication that eel are still making their way into many of these marshland waterways.

Just as importantly, the project highlighted which structures may be acting as migration barriers. Our results are now guiding the NKMIDB’s next steps — from targeted barrier surveys to potential installation of eel passes and ropes.

What We Learned

This project reinforced the value of combining eDNA with community participation:

• Accessible methods – With the right training and kit, volunteers can collect high-quality eDNA samples. This was one of the most challenging environments from which to filter eDNA samples, due to the unusually turbid water, with a fair amount of perseverance, the samples were collected with no contamination in the field controls, congratulations team!

• Data for decision-making – Even where we can’t measure abundance, eDNA provides clear presence/absence data to guide habitat restoration and barrier mitigation.

Looking Ahead

The results from this pilot will feed directly into future eel passage improvements across the Hoo Peninsula. Plans are already in motion to combine eDNA surveys with structured barrier assessments, apply GIS mapping for prioritisation, and expand volunteer involvement.

We’re proud to have played a part in demonstrating that even a critically endangered species can be monitored effectively with the help of local communities — and that these insights can be turned into real conservation action.

"Thank you so much for your patience and invaluable support – you have made the project much easier to deliver" - Anita Soloman, Lower Medway Internal Drainage Board