Ecological impacts on the distribution of Ganges River dolphin (Platanista gangetica) in the lower Gangetic plains and its conservation challenges

Despite threatened status, the Ganges River dolphin (Platanista gangetica) received insufficient attention in many habitats including the lower Ganges. In this study, through standardised monitoring programmes, we recorded the population and distribution of the species from a 100-km long stretch of the lower Ganges between January and December 2023. Important ecological parameters (e.g. fish abundance and water quality parameters) were also monitored to understand their effects on dolphin population in the river. Number of Ganges River dolphin varied over time (ANOVA: F11,88 = 10.9, p < 0.001) and space (F8,88 = 24.1, p < 0.001). Maximum number of dolphin was sighted in the month of August; whereas, the minimum was in February. Population of Ganges River dolphin was affected positively by fish abundance (LMM: F = 19.7, p < 0.001) and water transparency (F = 4.4, p = 0.042) and negatively by total dissolved solids (TDS; LMM: F = 13.5, p = 0.001). A range of challenges related to fishermen’s knowledge and attitude towards the Ganges River dolphin were identified. These include lack of awareness, high market demand and price for the species and negative attitude towards the species. Illegally harvested Vulnerable dolphins were sold only to produce dolphin oil to catch another Endangered fish species Clupisoma garua. The results of this study have conservation management applications and implications.