NatureMetrics and NIRAS have a long-standing commercial partnership. Together we have delivered more than 40 eDNA projects across Swedish freshwaters, the Baltic Sea and the Arctic, for clients in hydropower, offshore wind and local government.

This client story looks at one of those projects. The Blekinge County Administrative Board commissioned NIRAS to map the fish community in Gåsefjärden, part of the Karlskrona archipelago. By running eDNA alongside conventional net fishing, the project showed that eDNA can deliver comprehensive fish community data with minimal disturbance to the ecosystem and less risk to field teams.

Comprehensive fish data, minimal disturbance

The Blekinge County Administrative Board needed a survey method that could deliver comprehensive data on fish species while minimising environmental disturbance.

NIRAS and its client wanted to compare eDNA and conventional net fishing directly. Their aims were to understand the relative merits of each approach and to gather as much data as possible.

NatureMetrics supported NIRAS in designing and deploying a sampling programme that combined both methods:

• 45 stations were surveyed using net fishing.
• 17 stations were surveyed using eDNA.
• 16 stations were assessed using both methods at the same time, allowing a direct comparison.

A single 3-litre water sample was collected at each eDNA station. This generated comparable biodiversity data with significantly less environmental impact than net fishing.

The parallel comparison showed that eDNA could deliver comprehensive fish community data while causing minimal disturbance to the ecosystem and reducing risk to field teams.

The results validated eDNA as a practical, lower-impact alternative to conventional methods for fish biodiversity surveys in coastal and freshwater environments.

Larger datasets, lower impact

• Bigger, more cost-effective datasets: eDNA allows NIRAS to offer its clients larger and more cost-effective fish datasets.
• Ethical, non-invasive surveying: eDNA addresses the ethical and conservation concerns that come with traditional net fishing.
• Safer fieldwork: Collecting water samples reduces the risks field teams face compared with net fishing.
• A growing partnership: The project adds to more than 40 eDNA projects delivered through the NatureMetrics and NIRAS partnership across Swedish freshwater, Baltic Sea and Arctic environments.