Application of environmental DNA technology in marine ranching-case study of Bailong Pearl Bay Demonstration area in Beibu Gulf

•A complete eDNA workflow was established for the Marine Ranching Demonstration area.•The artificial reef marine ranch demonstration area in Beibu Gulf has achieved remarkable results.•Environmental factors have different effects on fish in different habitats.•Fish diversity distribution in the different four areas was different and the overall fish community is changing to smaller species.