Distribution and Conservation Threats of Softshell Turtles (Nilssonia spp.) in Morang District, Nepal

Abstract

Softshell turtles (Nilssonia spp.) are freshwater turtles that act as natural scavengers and indicators of freshwater ecosystem health. Five species of softshell turtles are recorded across Southeast Asian countries, with three species, Nilssonia nigricans, N. hurum and N. gangetica being native to Nepal. This research aimed to assess the distribution and anthropogenic threats faced by Nilssonia spp. in Morang District of eastern lowland Nepal and propose potential conservation solutions. This study analyzed environmental and anthropogenic variables affecting distribution of the three turtle species in the eastern lowlands of Morang, Nepal, considering factors such as pH, dissolved oxygen (DO), habitat types (ponds, rivers, wetlands), water depth, connectivity, and the Human Disturbance Index (HDI). The variables are based on their documented relevance to aquatic ecosystems and turtle ecology. The results revealed that temperature (CI = –0.83 to 2.06, estimate = 0.4222, p > 0.05), pH (CI = –5.40 to 0.43, estimate = –1.8473, p > 0.05), river habitats (CI = –1.82 to 30.74, estimate = 6.7434, p > 0.05), wetlands (CI = –3.12 to 24.75, estimate = 4.7402, p > 0.05), and connectivity (CI = –23.74 to 1.5, estimate = –6.8630, p > 0.05) did not show significant effects on turtle occurrence. However, the HDI (CI = –13.13 to –2.80, estimate = –5.7479, p < 0.05)) had a significant negative influence on their distribution. The width of carapace from live turtle specimens was significantly smaller than that of the old carapaces indicating over harvesting of the species. Electrocution, habitat fragmentation and excessive exploitation of resources are the major threats to the softshell turtles in the study area. A questionnaire survey with pre-structured questions was done among the local inhabitants of the study area. Fishing, habitat modification and poisoning were identified as the major conservation threats to softshell turtles in the study area. This study identified human disturbance as a major conservation threat to the softshell turtles in Morang District and suggests for formulating species specific management and conservation strategies.