Current knowledge and limitations of eDNA as a monitoring tool for European eel

Sammanfattning

Monitoring organisms and ecosystems is essential to provide baseline information against which we can evaluate changes and extremes. This is especially important for critically endangered species, such as the European eel (Anguilla anguilla). Today we monitor European eel by the means of trawling, netting and electrofishing, among other methods. eDNA is a relatively new, non-invasive and non-lethal monitoring method that analyses what organisms reside in a system based on what DNA can be found in environmental samples. The aim of this study was to explore the use of eDNA in the monitoring of fish, with emphasis on the European eel. A literature search was performed and the 22 articles reviewed were divided into nine categories, based on the perceived area of use. The most common category was using eDNA to detect European eel (11 studies). Using eDNA to estimate abundance and/or biomass was less common (4 studies) and the results of these studies were less consistent. Using eDNA to confirm absence, detect parasites, and detect hybridization were the least common categories (1 study each). The lack of knowledge surrounding how to estimate abundance and/or biomass with eDNA seems to be the largest challenge to using eDNA in current eel monitoring programs and will likely be investigated more in the future.