Ganges river dolphins are freshwater dolphins that inhabit the Ganges, Meghna, Brahmaputra, and Karnaphuli-Sangu river systems in Nepal, India, and Bangladesh.
They are one of the oldest species of dolphin still existing today. Unfortunately, due to their endangered status, there are less than five thousand Ganges river dolphins left in the entire world. This is in stark contrast to the more than four hundred million people living in the Ganges River basin.
Other names: Susu, Sus, Swongsu, Soonse, Sunsar, Hiho, Shihu, Shusshuk, Foomach and Sishumaach.
IUCN conservation status: Endangered
What do Ganges river dolphins look like?
This greyish-brown dolphin has an unusual looking head and face. Their eyes are teeny and only visible as small pinhole openings just above the end of their upturned mouth line. The very long, slender snout is lined with lots of sharp, pointy teeth which get longer towards the tip and are visible on the outside of the mouth. The dorsal fin is more of a low hump and the belly is rounded which gives these dolphins a stocky appearance. The triangular-shaped flippers are large and broad; they are squared-off at the end and have a crenulated trailing edge. The tail flukes are also large and wide.
What’s life like for a Ganges river dolphin?
Ganges river dolphins are sometimes called ‘blind dolphins’. They live in rivers that are brimming with sediment that has been washed downstream from the Himalayas. Light doesn’t penetrate through the brown water, so there is no need for eyesight to navigate their surroundings. Instead, the dolphins use echolocation clicks to explore and find food.
Ganges river dolphins are not demonstrative or acrobatic; they tend to surface quickly and discreetly, with the occasional snout peeking above the water. Typically, they are spotted alone or in pairs, sometimes in small groups. Individuals tend to congregate in spots along the river that offer optimal fishing opportunities, such as counter-current pools formed near channel intersections, mid-channel islands, sharp bends, and man-made structures like bridge pilings. These locations assist in the accumulation of nutrients and fish within the river.
One notable characteristic of these dolphins is their highly flexible necks, which differ from most other dolphins due to their unfused vertebrae. This flexibility allows them to move their heads in a sweeping motion while echolocating. They swim upside down and on their sides, using one flipper to detect prey in the riverbed's murky waters. Ganges river dolphins are thought to reach sexual maturity at between 6 and 10 years old. Each pregnancy lasts about a year and the calves stay with their mothers for a year before they are weaned. Lifespan is estimated at up to 30 years.
What do Ganges river dolphins eat?
Ganges river dolphins eat a variety of freshwater fish and invertebrates. Their long, thin snouts are designed for quick snapping actions to capture fast prey.
Where do Ganges river dolphins live?
Ganges river dolphins live in rivers spilling from the Himalayan foothills in Nepal and India and flow through northern India and Bangladesh to the Bay of Bengal. Ganges river dolphins live in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river basins that span Nepal, India and Bangladesh.
During high water seasons created by monsoon rains, Ganges river dolphins are able to spread out and live in seasonal tributaries and lakes as well as the main river channels.
What's in a name?
Ganges river dolphins have many local names throughout the countries where they live. Most are related to the sound people hear when the dolphins surface to breathe. These include Sus and Swongsu (Nepali); Susu, Soonse and Sunsar (Hindi); Hiho and Shihu (Assamese); and Shusshuk, Foomach and Sishumaach (Bengali).
An endangered species
Ganges 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 Ganges 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 Ganges River dolphin lives in one of the world’s most densely populated areas. Their overall range has shrunk and the remaining dolphins are divided into four subpopulations, isolated from one another by barrages.
Ganges river dolphins share their river habitats with crocodiles (gharials), freshwater turtles and wetland birds.
Ganges river dolphins are legally protected from hunting in all three countries they live in.
Compared to other river dolphins, Ganges 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.
Ganges river dolphins need your help
The main threats...
Regrettably, the life of every single surviving Ganges river dolphin is full of hazards and dangers.
- Dams and Barrages - the biggest threat Ganges river dolphins face is the existence of dams and barrages built to alter rivers for human benefit. These structures are insurmountable physical barriers to the dolphins and prevent their free movement and seasonal migration in rivers. They have reduced the complexity of natural river flow and ecosystems and reduced habitats available for the dolphins. The surviving dolphins are now divided into isolated and vulnerable subpopulations. Dolphins trapped upriver of some dams have already disappeared. More dams and barrages are under construction or planned, driven by higher demands for freshwater supplies for agriculture, industry and urban areas and so Ganges river dolphin populations will continue to decline, unless protection is put in place for them.
- Fishing nets - Ganges river dolphins get caught accidentally and die in gillnets. Both fishermen and dolphins fish in the same parts of the river where nutrients are richest and the fish are concentrated.
- Pollution- levels of pollution in rivers of South Asia are increasing and can be expected to carry on increasing as development is ongoing and there are few controls on pollutant discharges. Rivers are less able to dilute pollutants because water is increasingly removed to supply agricultural and industry demands.
- Direct takes – Although fully protected by law, some individuals are still known to be taken illegally and in some areas, due to a lack of awareness, individual dolphins are targeted out of an unsubstantiated fear of competition for prey.
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