Fathom Ecology: eDNA as a Fisheries Management tool

The Client

Fathom Ecology Ltd is a small consultancy advising on environmental data for infrastructure projects. The company provides specialist ecological advice in marine, estuarine, and freshwater environments, and advises on mitigation and compensation measures to reduce risk to developers and the environment.

The Problem

Fathom Ecology was commissioned to determine whether European eel (Anguilla anguilla) was present within a series of ponds and connected watercourses prior to a proposed development. As the European eel is listed as Critically Endangered by the IUCN and is protected under UK and European legislation, it was essential to establish whether the species was present before recommending further survey work or mitigation.

Without knowing at which sites European eel was likely to be present, traditional methods would have been too expensive and time consuming to conduct.

“Traditional fisheries surveys such as electrofishing require specialist equipment, trained personnel and suitable site access, and are best undertaken where there is evidence that target species are likely to be present,” said Rayner Piper from Fathom Ecology.

Our Solution

We used our comprehensive biodiversity service to survey 4 ponds, which provided information on the presence/absence of European eels at each site, as well as wider data on overall biodiversity and species presence.

This allowed eDNA to act as a rapid, sensitive, and non-invasive screening tool to assess whether European eel was present before committing to more detailed fisheries surveys and management.

Rayner commented that the sampling process was “straightforward, efficient and considerably quicker than many conventional fisheries survey techniques. Sample collection required very little equipment, could be undertaken by a single surveyor and caused virtually no disturbance to either the waterbody or the surrounding habitats.” They noted that it was “particularly advantageous within the ponds, where access was often restricted and minimising disturbance to protected habitats and species was an important consideration.”

“The sampling protocols provided by Trace Biomonitoring were clear, practical and easy to follow, giving us confidence that samples could be collected consistently whilst minimising the risk of contamination,” said Rayner.

What We Found

We detected the presence of European eel in just one of the ponds surveyed, and three connected watercourses. This allowed Fathom Ecology to focus their subsequent survey recommendations on the locations where eels were confirmed to be present, avoiding unnecessary invasive surveys and interventions.

“The eDNA survey formed an important first stage in a risk-based assessment, allowing our client to make informed decisions whilst minimising unnecessary disturbance to aquatic habitats and ensuring that survey effort was directed where it was genuinely required,” said Rayner.

We also detected 962 taxa across the sites sampled, including two at-risk species (European eel and common ash), six invasive species, and 15 fish to species-level. “One of the most valuable aspects of the survey was the additional ecological information that was obtained,” said Rayner, “the analysis identified a diverse fish assemblage across the survey area, providing valuable baseline ecological data that will help inform the wider ecological assessment of the site.”

Read the full report here.

The Impact

Fathom Ecology were able to use the data from our surveys to provide evidence that mitigation work should commence to protect European eels at locations that would be affected by development work.

By using eDNA, Fathom Ecology were able to prioritise funding and effort on the locations that mattered most. Rather than replacing conventional fisheries surveys, they used eDNA as a complementary part of the survey, allowing them to design more efficient and evidence-led programmes. They commented that “sample collection required only a fraction of the time that would have been needed to undertake conventional fisheries surveys across every waterbody…From a consultancy perspective, eDNA represents excellent value because it enables large areas to be screened rapidly, allowing conventional fisheries surveys to be deployed more strategically and only where they are likely to provide additional ecological benefit.”

The project showcased eDNA’s ability as a screening tool for sensitive species, but also demonstrated the value of the additional data received from our comprehensive biodiversity service. Fathom Ecology gained additional insight into the ecology of the area they were surveying, which added context and value that they would not have achieved through traditional survey methods.

“We see significant opportunities to integrate eDNA into our standard approach for fisheries projects, particularly where the objective is to establish species presence before recommending more intensive field investigations”, said Rayner. “As an aquatic ecology consultancy, we anticipate incorporating eDNA into a wider range of projects, including fish rescue planning, Water Framework Directive investigations, river restoration schemes, ecological impact assessments and post-construction monitoring.”