Movements and Home Ranges of an Endangered Freshwater Fish, Pseudobagrus brevicorpus, and the Impact of River Management

An ecological understanding of threatened species provides the basis for their protection and recovery. This information must be used to analyze threats in order to propose conservation strategies for target species. River management projects, such as the construction of dikes, revetments, and dredging, are often undertaken to prevent flooding, and these activities affect fish communities and population dynamics. The critically endangered Pseudobagrus brevicorpus is highly vulnerable, but the causes of its decline are poorly understood. In this study, we assess the movements and habitat selection of P. brevicorpus to better understand its ecological characteristics and analyse the causes of its decline. We used radio telemetry to track the movements of the species and compared the effects of river-maintenance projects with data from a long-term study of the distribution of this endangered species. Total movements and home ranges were quite limited, with an average total distance traveled of 107.58 ± 66.01 m over an approximately 8-week monitoring period. The average MCP (minimum convex polygon) was 341.91 ± 776.35 m2, the KDE (kernel density estimation) 50 was 76.01 ± 30.98 m2, and the KDE 95 was 144.41 ± 58.86 m2. The species is nocturnal, and during the day, individuals primarily hide among rocks and aquatic roots. The movement and habitat selection of P. brevicorpus indicated that the species could be directly or indirectly affected by river management. Acute population declines have been anticipated due to a lack of avoidance during management, and post-management habitat loss appears to have contributed to long-term population declines. Therefore, a strategic approach that considers ecological consequences is urgently needed to prevent the extinction of this species.