The Indus River dolphins may not be as beloved as their more famous cousins, but they are at a much higher risk of disappearing.

In a secluded pocket of Pakistan’s Lab-e-Mehran park, the smooth waters of the Indus River break into circular ripples, and the head of a pale gray dolphin appears. The animal lingers briefly before diving back into the water, its dorsal fin gleaming in the sun.

This quiet riverside park in the southern city of Sukkur, popular with families out for a stroll, is also home to the endangered Indus River dolphin, one of only four freshwater dolphin species left on Earth.

These animals, which weigh up to 200 pounds and can grow up to 8.5 feet long, are found only in the freshwater Indus River in South Asia. They have small, poorly-developed eyes that lack a crystalline lens, which make them practically blind to their surroundings.

As an adaptation, they navigate the muddy waters of the Indus River relying solely on echolocation.
But a dam at the western end of the park restricts their ability to travel freely during the monsoon season, a crucial part of their life cycle.

With just about 1,500 Indus River dolphins left on the planet, these gentle creatures are considered to be one of the world’s most endangered groups of animals. Their population numbers went down drastically after an irrigation system was built and they continue to be hunted by local fisherman for bait, meat and medicine.

The remaining Indus dolphins are concentrated mostly in the Pakistani province of Sindh, in a 410-mile stretch of river between the Guddu and Kotri dams. Engro, an energy company that works with the thermal power plant connected to Guddu dam, did not respond to requests for comment about the dam’s impacts on the species.

Beyond dams, water pollution and industrial waste dumped into the Indus pose the gravest long-term threat to the dolphins. Studies have found DDT and other pesticides in the animals’ tissue, according to Uzma Khan, Asia coordinator for WWF’s River Dolphins Initiative.

The biggest challenge to saving animals like this elusive dolphin is lack of knowledge. They have not been widely studied and there is very little literature about them.

Researchers are taking an especially close look at the Indus River dolphin because they don’t want the same fate of the Yangtze River dolphin to fall on them. The Yangtze River dolphin hasn’t been spotted for decades and it believed to be extinct, but its decline and disappearance was so quick that conservationists didn’t have time to act.

Fishermen in these provinces tell an origin story for the species. In the legend, when a woman offers butter and milk to a mystic patron of the river, the waters part and she safely crosses to the other side. But once, she fails to make an acceptable offering—and the river spirit transforms her into a dolphin.

WATCH AN INDUS DOLPHIN RESCUE