Featured Image Credit: WWF
By: Kira Krall
The Indus River dolphin once called the entire Pakistani river and its tributaries home. They’ve now been separated into isolated populations because of hydrological changes that were made in the 1930s. Certain parts of the lower Indus face even stronger droughts with this man-made change, leaving the dolphins with few habitat options. The dolphin locally known as bhulan had decreased to 1,100 members in 2001. Despite pressure from habitat loss and bycatch, the dolphins have made a comeback. World Wildlife Fund Pakistan recently did a survey of the second most endangered freshwater dolphin the world and found that at least 1817 bhulan now grace Indus waters, the only place in the world you can find the freshwater cetacean.
The research team set out for the 620-mile-long river and began counting the blind dolphins. The Indus has such poor visibility that the bhulan’s eye lenses never evolved. They rely exclusively on echolocation to hunt and navigate. Bhulan have also developed a behavioral adaptation to life in the river. The 8-foot mammal swims on its side, which lets it swim in water as shallow as 11 inches. Every 30-60 seconds when it needs to breathe, the dolphin rotates 90 degrees to expose its blowhole to the air, then rotates 90 degrees back down and continues its sideways swim. They’ve perfected the art of navigating murky and shallow water to follow the food and avoid getting stranded.
Indus River Dolphins are facing some major threats, the largest being human hydrological changes. The 1930s dam projects rerouted the River’s water into agricultural irrigation fields. Draining the Indus left dry patches that even the bhulan couldn’t navigate and has reduced their range by as much as 80%. The remaining small subpopulations now face inbreeding and are more likely to develop genetic issues and an inability to fight diseases. Until the 1970s, fishermen hunted them for their oil and meat. Bhulan are still affected by commercial fishing in the form of bycatch and illegal poaching. Runoff from the land dumps pollutants like pesticides, chemicals, and raw sewage into the river, which work their way into the dolphin’s prey.
In 1974, World Wildlife Fund Pakistan works with the Sindh Agriculture Extension Department to reduce agricultural pollution sources near the Indus. They educate farmers, communities, and fishermen on ways they can contribute to a healthier bhulan population. Read more from the WWF Pakistan study here and learn more about the Indus River dolphin here.