Ganges River Dolphin

Appearance

The Ganges river dolphin has a rectangular, ridgelike dorsal fin and females tend to be larger than males. Ganges river dolphins usually are tan, chocolate brown, dark grey or light blue. They have an elongated, slender snout with sharp and very pointed teeth, similar to most river dolphins. The river dolphin has a rounded belly which, combined with their rectangular dorsal fin, makes them look particularly stocky in build compared to other dolphins. Their flippers and tail flukes are large and broad. They have a large melon head used for echolocation, because they cannot see well. Their eyes are usually small due to the cloudy water. Ganges river dolphins are usually 2.2–2.6 meters long. The oldest recorded animal was a 28-year-old male, 199 cm in length, although they are estimated to live up to 30 years old.

Naming

The species has multiple common names throughout its range. It is known as "susu" as a popular name, "soons, soans", or "soos" in Hindi, "shushuk" in Bengali, "hiho" or "hihu" in Assamese, "bhagirath", and "shus" or "suongsu" in Nepali. Its Sanskrit name in medieval times was likely "shishumar", and during the Mughal era, it was known as "pani suar".

Distribution

It lives along the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, and the Sapta Koshi and Karnali Rivers in Nepal. The Ganges river dolphin favours deep pools, eddy countercurrents located downstream of the convergence of rivers and of sharp meanders, and upstream and downstream of midchannel islands.

Status

In 2017, it was estimated that the global Gangetic river dolphin population comprised less than 3,500 individuals. The underlying surveys are temporally patchy and believed to contain uncertainty.

The Ministry of Environment and Forest declared the Gangetic dolphin the national aquatic animal of India. A stretch of the Ganges River between Sultanganj and Kahlgaon in Bihar has been declared a dolphin sanctuary and named Vikramshila Gangetic Dolphin Sanctuary, the first such protected area.

The Uttar Pradesh government in India is propagating ancient Hindu texts in hopes of raising the community support to save the dolphins from disappearing. One of the lines being versed from Valimiki's Ramayana, highlighted the force by which the Ganges emerged from Shiva's locks and along with this force came many species such as animals, fish, and the Shishumaar—the dolphin.

On 31 December 2020, a dead adult dolphin was found at the Sharda canal in the Pratapgarh district in India. A video circulated on social media showing a dozen men beating the dolphin with sticks and an axe. On 7 January 2021, three people were arrested. Similarly, there is another news story in which a few fishermen caught one Gangetic dolphin and feasted upon it, leading to their arrest by Kaushambhi police in Uttar Pradesh.

The species is protected from international trade by its listing in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. This makes commercial international trade prohibited.

Bangladesh has established six sanctuaries in the Sundarbans.

On 20 May 2013, India's Ministry of Environment and Forests declared dolphins 'nonhuman persons' and as such has forbidden their captivity for entertainment purposes; keeping dolphins in captivity must satisfy certain legal prerequisites.

Behavior

The Ganges river dolphins usually swim alone or in pairs, they are known to breach rarely and are shy around boats and therefore difficult to observe.

Reproduction

The Ganges river dolphin does not have a specific mating season. When a calf is born, 8–12 months after conception, it stays with its mother for one year.

Food

The Ganges river dolphin finds food through echolocation and feeds on crustaceans such as prawns and fish including carp, mahseer, and even sharks such as the Ganges shark. It also takes birds and turtles.

Predators

The Ganges river dolphin has been listed as an Endangered species on the IUCN Red List since 1996. It is threatened by habitat fragmentation due to reduced dry-season river flows, entanglement in fishing gear and by-catch mortality, targeted hunting, pollution of rivers in proximity to urban areas and intensive agricultural landscapes; it is disturbed by inland navigation and potentially threatened by seismic surveys, oil well blowouts, and the effects of climate change on hydrological dynamics.
Human activity has played a large role in the reduction of its native range and population size due to stressors such as noise pollution, ship traffic and fishery bycatch, construction of dams and hydroelectric power plants. It is also endangered due to pollution and overfishing for oil. Entanglement in fishing nets as bycatch can cause significant damage to local populations, and individuals are taken each year by hunters; their oil and meat are used as a liniment, as an aphrodisiac, and as bait for catfish. Poisoning of the water supply by industrial and agricultural chemicals may also have been a contributing factor towards population decline, as these chemicals are biomagnified in the bodies of the dolphins....hieroglyph snipped... An immediate danger in National Chambal Sanctuary is the decrease in river depth and appearance of sand bars dividing the river course into smaller segments.

Cultural

The Ganges dolphin is associated with Ganga and is occasionally the depiction of her vahana, the makara.