There is a need to develop new approaches that can effectively detect biodiversity hotspots important areas for conservation. We developed a species-specific eDNA assay for the Chilean devil ray, Mobula tarapacana, to assess the capability of using eDNA to detect transient pelagic marine animals. Seawater samples taken at seamounts around the Azores (NE Atlantic) were tested for the presence of the ray and, our assay successfully detected M. tarapacana at four out of five seamount sampling opportunities where the species was observed.

This study has shown the potential of eDNA techniques as a rapid and relatively inexpensive tools for detecting transient species where traditional surveying methods are not feasible. The results indicate that this tool (assay) can be further developed, combined with visual observations to establish modelling approaches and used to delineate the spatial and temporal distribution of poorly understood species, such as the Chilean devil ray, and improve our capabilities to identify important areas for conservation where vulnerable species reside.