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

Siamese bat catfish ( 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 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 . Therefore, this study developed an eDNA assay targeting a 160 bp fragment of the 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. 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 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.