An environmental DNA assay for the detection of Critically Endangered angel sharks (<i>Squatina</i> spp.)

The three sympatric angel shark species occurring in the Mediterranean – Squatina squatina (the angelshark), aculeata sawback and oculata smoothback angelshark) are all classed as Critically Endangered on International Union for Conservation of Nature (IUCN) Red List. There is a clear need to better quantify their current status, using appropriate non-destructive methods, help inform future conservation measures. This study introduces an environmental DNA (eDNA) assay able detect distinguish S. aculeata, oculata, Sea by combining probe-based quantitative polymerase chain reaction (qPCR) technology Sanger sequencing. targets 173-bp barcode mitochondrial cytochrome c oxidase I (COI) gene. It was tested silico, vitro tissue-extracted DNA, eDNA extracted from filtration samples. genus-specific applied presence samples collected Corsica, France. target found seven 76 samples, revealing north-western where has never been observed, confirming its existence eastern coast. also demonstrates that sampling, based 30 L seawater filtered close substrate with waterproof peristaltic pump, it possible this rare benthic species. results detection can identify critical areas facilitate development local public awareness initiatives. novel qPCR should be used applications Atlantic targeting sharks remaining populations. In eDNA, but application still needs validated field.