The Indus River dolphin lives in the Indus river basin of Pakistan and India.
Unfortunately, there are currently less than two thousand of these endangered dolphins left in the world. However, there have been some promising signs of increasing numbers, which can be attributed to better protection measures in Pakistan.
Other names: Bhulan
IUCN conservation status: Endangered
What do Indus river dolphins look like?
Indus river dolphins are typically light brownish-grey in colour, sometimes with lighter undersides. Adult dolphins can reach lengths of up to 2.5 metres and weigh between 70 to 110 kg. Their long and thin rostrum is adorned with visible teeth, even when their mouths are closed. Their eyes are incredibly small, with pinhole-sized openings, and they have a small triangular hump as their dorsal fin. Additionally, they have large flippers, tail flukes, and flexible necks.
What’s life like for an Indus river dolphin?
Indus river dolphins are typically solitary, although they can gather in groups of up to 30 individuals. They are not acrobatic dolphins and keep a low profile; only surfacing quickly before diving for over a minute. They prefer to keep their distance from humans.
Indus river dolphins can usually be found where the best fishing spots are such as counter-current pools created near channel convergences, mid-channel islands, sharp meanders and man-made structures such as bridge pilings. These features help to concentrate nutrients and fish in the river.
Indus river dolphins utilize a distinctive side-swimming technique to navigate through shallow waters. They have adapted to living in murky river water and cannot see. Instead, they rely on echolocation to locate food and find their way around underwater. In contrast to other dolphin species, Indus river dolphins possess flexible necks and move their heads from side to side to scan their surroundings while constantly emitting echolocation clicks.
Indus river dolphins typically reach sexual maturity at around 10 years old. While mating can occur at any time of the year, the period between March and May seems to be associated with a higher frequency of births. Following a gestation period of 8-9 months, a single calf, typically measuring around 70cm in length, is born and nurtured with their mother's milk. Although there is limited information about their lifespan, the oldest known Indus river dolphin lived to be 39 years old.
What do Indus river dolphins eat?
Indus river dolphins eat a large variety of freshwater fish including catfish and carp, and prawns. Their long, thin snouts are designed for quick snapping actions to capture fast prey.
Where do Indus river dolphins live?
Indus river dolphins are found mostly in the lower parts of the Indus River in Pakistan. The dolphins historically swam freely through about 3500 km of the Indus River system from the Karakoram mountains to the Indus delta. Their range has been reduced by approximately 80% due to the construction of irrigation barrages, and now most of the remaining dolphins are in a 690 km stretch of the Indus River in three separated populations. A handful of Indus river dolphins also occur in the Beas River in India, trapped in the upper section of the river above an irrigation dam.
Indus river dolphins prefer the deepest river channels and are less common in secondary or side channels and in small braids. During the low-water season (October to April), barrages divert a large amount of the river’s flow such that the dolphin habitat downstream of Sukkur Barrage and in most tributaries has been eliminated. As water levels drop in the winter, dolphins are concentrated in the remaining deep areas.
An endangered species
Indus river dolphins are rated by IUCN as Endangered due not only to the huge reduction in their overall numbers, but also the ongoing shrinking of their habitats and freshwater places they are able to live.
The range of the Indus river dolphin is predicted to continue to diminish as those living in sections of rivers isolated from others by dams and barrages disappear due to further habitat loss and climate change.
The Indus River dolphin is now limited to a 700 km stretch of the Indus mainstream which is about one-fifth of their historical range. More tragically, the last surviving dolphins are separated into three subpopulations and isolated from each other by barrages and this isolation makes them more vulnerable to other threats.
Indus river dolphins share their river habitats with crocodiles (gharials), freshwater turtles and wetland birds.
Indus river dolphins are legally protected from hunting in Pakistan and India.
Compared to other river dolphins, Indus river dolphins have smaller brains but the part of the brain used for acoustic functions is well developed.
Although they cannot see images as their eyes lack lenses to focus, they do have an optic nerve and retina and so can detect light and dark.
The ear opening is above the eye which is unlike that of other dolphins whose ear openings are just behind the eye.
Unfortunately, these dolphins sometimes become stranded and trapped in irrigation canals as water levels fall in the dry season and their only hope is human rescue.
Indus river dolphins need your help
The main threats...
Pakistan is a country that consists mainly of desert, has a constantly increasing human population, and rapidly developing industrial and agricultural sectors that require more and more water. Unfortunately, this has caused significant damage to the rivers and has led to the loss of the habitat of river dolphins.
- Dams and Barrages - The Indus river dolphin faces significant threats from the widespread building of dams, barrages, and river water diversions. These manmade structures cause river flow regulation and habitat fragmentation, which reduces connectivity and isolates dolphins in specific river sections. Indus river dolphins are also at risk of becoming trapped in irrigation canals and may die unless rescued.
- Fishing nets also pose a significant risk, as dolphins become entangled and drown. Eighty Indus dolphins have died in gill net entanglement since 2008 in a 190km stretch of the river.
- Pollution from domestic, industrial, and agricultural sources can harm the health of the dolphins, as they are long-lived top predators. Heavy metals, industrial pollution, and agricultural run-off can all contaminate their river homes and negatively impact their health.
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