In Hong Kong waters, two resident cetacean species are found: the Indo-Pacific humpback dolphin (also known as the Chinese white dolphin; Sousa chinensis) and the Indo-Pacific finless porpoise (Neophocaena phocaenoides). These species play an important role in coastal ecosystems as top predators, yet their populations are declining due to human activities. Environmental DNA (eDNA) analysis, which extracts DNA directly from environmental samples such as water, is a promising method for monitoring threatened species efficiently. Although eDNA analysis has been widely applied to various organisms such as fish, mammals, and birds, its use for cetaceans remains limited. In this study, we developed cetacean-specific eDNA metabarcoding primers and species-specific quantitative PCR (qPCR) primers to improve the efficiency of eDNA-based cetacean monitoring in Hong Kong waters. We carefully validated the sensitivity and effectiveness of these methods through in silico analysis, laboratory experiments, and tank water tests, and then applied them to seawater samples collected from coastal areas in Hong Kong. The eDNA metabarcoding and qPCR successfully detected both resident cetacean species in Hong Kong waters. Although cetacean eDNA concentrations were generally low (e.g., below the limit of quantification), these successful detections demonstrate the sensitivity and usefulness of eDNA methods to improve the efficiency of cetacean monitoring. In this presentation, we will discuss potential applications of these approaches and propose new directions for integrating cetacean eDNA monitoring data with other eDNA and non-eDNA monitoring methods.
 

Cetacean,Environmental DNA (eDNA),eDNA metabarcoding,Hong Kong waters,qPCR