Detection of the Endangered Siamese Bat Catfish (Oreoglanis siamensis Smith, 1933) in Doi Inthanon National Park Using Environmental DNA

SIMPLE SUMMARY: Using traditional methods for surveying and monitoring Siamese bat catfish (Oreoglanis siamensis Smith, 1933), an endangered and endemic species in Thailand, is difficult. In this study, the eDNA-based method was used to confirm the O. siamensis habitat and its presence in the Doi Inthanon National Park, Chiang Mai, Thailand. Water samples were collected, and eDNA was analyzed by real-time PCR with species-specific primers. The eDNA of O. siamensis was detected in 12 samples out of 15 samples, inferring its distribution in the rivers of the Doi Inthanon National Park. The results showed that the eDNA-based approach can successfully detect O. siamensis in 300 mL turbid water samples. This information may be beneficial for the species management plan. The success of the eDNA-based method in O. siamensis detection indicates the usefulness of this method for rare species surveys in unfavorable environments. ABSTRACT: Siamese bat catfish (Oreoglanis siamensis Smith, 1993) has been listed as an endangered species, and its abundance has been severely declining due to habitat degradation and overfishing. To establish an appropriate management strategy, it is crucial to gain information about the distribution of this endangered species. As O. siamensis live under rocks in streams, detecting their presence is difficult. Recently, environmental DNA (eDNA)–based detection has been demonstrated to be a valid tool for monitoring rare species, such as O. siamensis. Therefore, this study developed an eDNA assay targeting a 160 bp fragment of the COI region to detect the presence of this species in its natural habitat. An amount of 300 mL of water samples (0.7 μm filtered) were collected from 15 sites in the Mae Klang sub-basin, where this fish species was visually detected at two locations. O. siamensis eDNA was detected at 12 of the 15 sites sampled with varying concentrations (0.71–20.27 copies/mL), including at the sites where this species was visually detected previously. The developed O. siamensis eDNA assay was shown to be effective for detecting the presence of this endangered species in the Klang Phat and Klang Rivers within the Doi Inthanon National Park.