a 2017 population assessment estimated less than 5,000 individuals for the species as a whole, of which about 3,500 belong to the ganges subspecies and about 1,500 to the indus subspecies. however, the underlying surveys are temporally patchy and believed to contain a large amount of uncertainty. current population trends are unclear. a demonstrable increase in the main river population of the indus subspecies between 1974 and 2008 may have been driven by permanent immigration from upstream tributaries, where the species no longer occurs.