eDNA complements scientific trawling in surveys of marine fish biodiversity components.

 Environmental DNA (eDNA) metabarcoding is a method to detect taxa from environmental samples. It is increasingly used for marine biodiversity surveys. As it only requires water collection, eDNA metabarcoding is less invasive than scientific trawling and might be more cost-effective. Here, we analysed data from both sampling methods applied in the same scientific survey targeting Northeast Atlantic fishes in the Bay of Biscay. We compared the methods in terms of spatial patterns of taxonomic, phylogenetic and functional diversity. We found that eDNA captured more taxonomic and phylogenetic richness than bottom trawling and more functional richness at the local scale. eDNA was less selective than trawling and detected species in local communities spanning larger phylogenetic and functional breadths, especially as it detected large pelagic species that escaped the trawl, even though trawling detected more flat fish. eDNA indicated differences in fish community composition that were comparable to those based on trawling. However, consistency between abundance estimates provided by eDNA metabarcoding and trawl catches was low, even after accounting for allometric scaling in eDNA production. We conclude that eDNA metabarcoding is an efficient method that can complement scientific trawling for multi-component biodiversity monitoring based on presence/absence. Here with provide the eDNA data set that support these findings.