Mongabay · Climate & nature

Endangered Dolphins Persist in Polluted Buriganga River

Despite extreme pollution, about 20 Ganges river dolphins survive in Bangladesh's Buriganga River, one of the world's most contaminated. Conservationists urge pollution control and safer fishing methods.

A 12-month study (Sept 2023-Aug 2024) found dolphins in a 27-km stretch of the Buriganga, a river heavily polluted by industrial effluent and sewage. Researchers were surprised by their presence, noting they hunted invasive catfish.

Dolphin sightings peaked in winter. Groups averaged 4.18 individuals, with calves comprising 16%, indicating reproduction. The river's heavy metal pollution exceeds safety limits, and oxygen levels are critically low.

Pollution has decimated native fish and caused biodiversity loss, with pollutants entering the food chain. The Buriganga is ranked the fifth most polluted river globally.

Conservationists stress that reducing pollution is vital. Excessive boat traffic also disrupts dolphin movement. A separate survey found over 2,000 Ganges river dolphins across 45 rivers in Bangladesh.

Twenty-seven dolphins were found in polluted stretches of the Turag, Buriganga, Bongshi, Surma, and Kalni rivers.

Bangladesh has established dolphin sanctuaries, but populations decline due to pollution and illegal gillnet fishing, which traps and kills them. Dolphins have vanished from previously inhabited rivers.

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