Assessing the conservation challenges for the European eel through the Delphi technique

The once abundant European eel (Anguilla anguilla) is currently classified as a Critically Endangered species by the International Union for Conservation of Nature. Although both the European Union (through the 2007 Eel Regulation) and its member states have implemented various conservation actions, many uncertainties remain regarding the actual and anticipated effectiveness of these measures. This study aimed to identify and prioritise the conservation and recovery measures for the European eel, using the expert-based Delphi technique. We conducted a two-round Delphi survey on eel conservation measures (these measures were derived from an extensive review of the peer-reviewed literature). The findings highlight the need for establishing a pan-European eel recruitment monitoring programme (to obtain reliable eel population estimates), restoring access to suitable inland habitats by removing migration barriers and improving habitat quality. Experts also emphasized the necessity for a more stringent silver eel escapement target and stronger enforcement of this target. While restocking of eel remains a contentious issue, a set of preconditions could render it conditionally acceptable. This study offers important insights into the areas of consensus and divergence among eel experts in the challenging field of eel conservation. We hope these results strengthen eel management decision-making such that this Critically Endangered species does not become a museum specimen for future generations.