About the Species
The Indus River dolphin, also known as the “bhulan,” is one of the world’s most endangered cetaceans. They are closely related to the Ganges River dolphin, also known as the “susu.” Their eyes are so small that scientists believe they are functionally blind, sensing only the levels and direction of light.
The main threats to the Indus River dolphin include entanglement, habitat degradation, noise, chemical contaminants, and vessel strikes. In 1991, NOAA Fisheries listed the Indus River dolphin as endangered under the Endangered Species Act.
Appearance
The Indus River dolphin is 7 to 8.5 feet long and weighs 150 to 200 pounds. Females are slightly larger than males. All Indus River dolphins have a rounded, stocky body with a small triangular fin located far down their back. Like other cetaceans, they have a distinctive "melon" on their head. This “melon” is a rounded forehead that collects sounds from the environment.
The Indus River dolphin’s back is gray and its belly is pale white or pinkish. Its small, poorly-developed eyes are located above the corners of the mouth.
Behavior and Diet
Indus River dolphins produce sound almost constantly to navigate, communicate, and find food. They make a sound similar to a sneeze when surfacing to breathe. These dolphins are usually found individually or in pairs but have been seen in groups of up to 10. They often swim on their side and rarely approach boats.
Indus River dolphins usually dive for 30 to 90 seconds but are able to hold their breath for several minutes. They use their long beaks to find food along the river bottom and groups of dolphins sometimes work together to find prey. Their fang-like teeth help them eat clams, fish, and shrimp.
Where They Live
Historically, the Indus River dolphin occurred from the Indus River delta to the shallow foothills of the Himalayas. It was also found in the tributaries of the Indus River. Today, its range is limited to the lower and middle areas of the Indus River in south-central Pakistan. This area represents only 20 percent of its historic range.
Indus River dolphins only occur in freshwater. They usually prefer shallow, murky waters, but are sometimes found in the main channels of rivers and tributaries during the flood season.
World map providing approximate representation of the Indus River dolphin's range.
Lifespan & Reproduction
Indus River dolphins can live for about 30 years. They reach sexual maturity when they are 6 to 10 years old. Adults breed throughout the year and females give birth to a single calf. Mothers nurse their calves for about one year.
Threats
Entanglement
One of the main threats to Indus River dolphins is getting entangled or caught in fishing gear, including gillnets and longlines. Indus River dolphins are accidentally captured in fishing gear mainly in the side channels and adjacent pools along the Indus River where fishing activity is greater due to higher densities of fish.
Habitat Degradation
Indus River dolphins are susceptible to habitat degradation and destruction. Human activities such as dredging and water withdrawals can damage Indus River dolphin habitats. Dams and irrigation canals also prevent Indus River dolphins from moving upstream and can separate populations from one another.
Ocean Noise
Underwater noise pollution interrupts the normal behavior of Indus River dolphins that rely on sound to communicate and echolocate. Noise interference from vessels, as well as industrial activities, disturbs Indus River dolphins’ feeding, communication, and orientation. If loud enough, noise can cause permanent or temporary hearing loss.
Chemical Contaminants
Contaminants enter the Indus River from many sources, such as wastewater discharges, agriculture, and other industrial processes. Indus River dolphins can accumulate chemicals in their bodies because of their long lifespan and position near the top of the food chain. These pollutants can harm river dolphins’ immune and reproductive systems. Chemicals can also kill fish, which reduces the amount of prey available for Indus River dolphins.
Vessel Strikes
Inadvertent vessel strikes can injure or kill Indus River dolphins. These dolphins are vulnerable to vessel collisions throughout their range, but the risk is much higher in some areas with heavy vessel traffic.
Scientific Classification
| Animalia |
Chordata |
Mammalia |
Cetacea |
Platanistidae |
Platanista |
gangetica minor |
Last updated by NOAA Fisheries on 10/30/2023
