The Buriganga River near Dhaka has long been turned into a drain for factories and waste, where oxygen nearly vanishes and heavy metals accumulate in the silt. Yet here, against all odds, about twenty Ganges river dolphins hold on.
A study conducted from September 2023 to August 2024 on a 27-kilometre stretch showed that the animals were present in the river ten months out of twelve. The greatest number of sightings came in winter, and the share of calves was almost sixteen percent — a sign that reproduction continues.
The local fish have almost disappeared, but invasive catfish capable of breathing atmospheric air have proliferated. According to the researchers, it is precisely these fish that the dolphins feed on, adapting to conditions that seem unfit for life.
The river's pollution is the result of discharges from tanneries, textile enterprises and household sewage. Concentrations of chromium, lead and cadmium regularly exceed safe norms, and in the dry season dissolved oxygen falls to almost zero. Such conditions are fatal for most aquatic organisms, but the dolphins so far find a way to exist.
Nationwide, a recent census recorded more than two thousand Ganges river dolphins in forty-five rivers of Bangladesh. However, in heavily polluted waterways such as the Buriganga and the Turag, their numbers remain small, and the threats are constant: illegal nets, intensive shipping and ongoing pollution.
Conserving these populations requires above all reducing industrial discharges and banning harmful fishing gear. Without these measures, even the dolphins' remarkable adaptability may prove insufficient.
