An eDNA survey of fish and crayfish presence in the Moälven River, Västernorrland County, was conducted on behalf of Moälvens FVO and Moälvsfisket to map species diversity and ecosystem impacts. eDNA samples were analyzed from 14 locations for fish detection and two locations for crayfish, resulting in the identification of 21 unique fish species and one species complex. The study found that eDNA was twice as effective as traditional electrofishing and gillnet surveys, highlighting the method’s high precision and sensitivity in monitoring aquatic ecosystems.
The survey confirmed the presence of the noble crayfish (Astacus astacus) at one of the two investigated sites, serving as an important indicator of water quality and ecosystem health. Analysis of water chemistry, migration barriers, and historical species introductions verified the fish distributions and demonstrated their role as biological indicators of environmental change.
The results are being used by the municipality and the County Administrative Board of Västernorrland as a basis for decision-making regarding measures to mitigate chemical and physical impacts from human activities, such as habitat degradation and water quality changes. This study enhances the understanding of fish population dynamics and environmental impacts, reinforcing eDNA as a powerful tool for long-term ecosystem management and conservation efforts in Moälven and other Swedish waterways.
