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Ganges and Indus River Dolphin

Ganges and Indus River Dolphin

Overview
The South Asian River Dolphin (Platanista) is a freshwater or river dolphin
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...

 found in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...

 and Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

 which is split into two sub-species, the Ganges River
Ganges River
The Ganges or Ganga, , is a trans-boundary river of India and Bangladesh. The river rises in the western Himalayas in the Indian state of Uttarakhand, and flows south and east through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. By discharge it...

 Dolphin
(Platanista gangetica gangetica) and Indus River
Indus River
The Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...

 Dolphin
(Platanista gangetica minor). The Ganges River Dolphin is primarily found in the Ganges and Brahmaputra Rivers and their tributaries in Bangladesh, India and Nepal, while the Indus River Dolphin is found in the Indus
Indus River
The Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...

 river in Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

 and its Beas
Beas River
The Beas River is a river in the northern part of India. The river rises in the Himalayas in central Himachal Pradesh, India, and flows for some 470 km to the Sutlej River in the Indian state of Punjab....

 and Sutlej
Sutlej
The Sutlej River is the longest of the five rivers that flow through the historic crossroad region of Punjab in northern India and Pakistan. It is located north of the Vindhya Range, south of the Hindu Kush segment of the Himalayas, and east of the Central Sulaiman Range in Pakistan.The Sutlej...

 tributaries.
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Encyclopedia
The South Asian River Dolphin (Platanista) is a freshwater or river dolphin
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...

 found in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...

 and Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

 which is split into two sub-species, the Ganges River
Ganges River
The Ganges or Ganga, , is a trans-boundary river of India and Bangladesh. The river rises in the western Himalayas in the Indian state of Uttarakhand, and flows south and east through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. By discharge it...

 Dolphin
(Platanista gangetica gangetica) and Indus River
Indus River
The Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...

 Dolphin
(Platanista gangetica minor). The Ganges River Dolphin is primarily found in the Ganges and Brahmaputra Rivers and their tributaries in Bangladesh, India and Nepal, while the Indus River Dolphin is found in the Indus
Indus River
The Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...

 river in Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

 and its Beas
Beas River
The Beas River is a river in the northern part of India. The river rises in the Himalayas in central Himachal Pradesh, India, and flows for some 470 km to the Sutlej River in the Indian state of Punjab....

 and Sutlej
Sutlej
The Sutlej River is the longest of the five rivers that flow through the historic crossroad region of Punjab in northern India and Pakistan. It is located north of the Vindhya Range, south of the Hindu Kush segment of the Himalayas, and east of the Central Sulaiman Range in Pakistan.The Sutlej...

 tributaries. From the 1970s until 1998, they were regarded as separate species; however, in 1998, their classification was changed from two separate species to subspecies of a single species (see taxonomy below). The Ganges river dolphin has been recognized by the government of India as its National Aquatic Animal.

Taxonomy


The species was described by two separate authors, Lebeck and Roxburgh, in 1801 and it is unclear to whom the original description should be ascribed. Until the 1970s, the South Asian River Dolphin was regarded as a single species. The two subspecies are geographically separate and have not interbred for many hundreds if not thousands of years. Based on differences in skull structure, vertebrae and lipid composition scientists declared the two populations as separate species in the early 1970s. In 1998, the results of these studies were questioned and the classification reverted to the pre-1970 consensus of a single species containing two subspecies until the taxonomy could be resolved using modern techniques such as molecular sequencing. Thus, at present, there are two subspecies recognized in the genus Platanista, the Platanista gangetica gangetica (Ganges River
Ganges River
The Ganges or Ganga, , is a trans-boundary river of India and Bangladesh. The river rises in the western Himalayas in the Indian state of Uttarakhand, and flows south and east through the Gangetic Plain of North India into Bangladesh, where it empties into the Bay of Bengal. By discharge it...

 dolphin) and the Platanista gangetica minor (Indus River
Indus River
The Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...

 dolphin).
Synonyms
  • Blind River Dolphin, Side-swimming Dolphin
  • Ganges subspecies: Gangetic Dolphin, Ganges Susu, Shushuk
  • Indus subspecies: Bhulan, Indus Dolphin, Indus blind dolphin

Physical description



The South Asian River Dolphins have the long, pointed noses characteristic of all river dolphins. The teeth are visible in both the upper and lower jaws even when the mouth is closed. The teeth of young animals are almost an inch long, thin and curved; however, as animals age the teeth undergo considerable changes and in mature adults become square, bony, flat disks. The snout thickens towards its end. The species does not have a crystalline eye lens, rendering it effectively blind
Blindness
Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness...

, although it may still be able to detect the intensity and direction of light. Navigation and hunting are carried out using echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...

. They are unique among cetaceans in that they swim on their side. The body is a brownish color and stocky at the middle. The species has only a small triangular lump in the place of a dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

. The flippers and tail are thin and large in relation to the body size, which is about 2-2.2 meters in males and 2.4-2.6 m in females. The oldest recorded animal was a 28 year old male 199 centimeters in length. Mature adult females are larger than males. Sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 is expressed after females reach about 150 centimetres (59.1 in); the female rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

 continues to grow after the male rostrum stops growing, eventually reaching approximately 20 centimetres (7.9 in) longer.

Distribution and habitat


The South Asian River Dolphins are native to the freshwater river systems located in Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, and Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

. They can be most commonly found in water with high abundance of prey and reduced flow.

The Ganges subspecies (P. g. gangetica) can be found along the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, although its range formerly extended to Nepal. A small subpopulation can be still found on the Karnali River and possibly the Sapta Kosi River.

The majority of the Indus subspecies (P. m. minor) is located between the Sukkur and Guddu barrage in the Sind Province
Sindh
Sindh historically referred to as Ba'ab-ul-Islam , is one of the four provinces of Pakistan and historically is home to the Sindhi people. It is also locally known as the "Mehran". Though Muslims form the largest religious group in Sindh, a good number of Christians, Zoroastrians and Hindus can...

 of Pakistan. Two smaller subpopulations have also been recorded in the Punjab and NWFP Provinces.

Biology


Births may take place year round but appear to be concentrated between December to January, and March to May. Gestation is thought to be approximately 9–10 months. After around one year, juveniles are weaned and they reach sexual maturity at about ten years of age. During the monsoon, South Asian River Dolphins tend to migrate to tributaries of the main river systems. Occasionally, individuals swim along with their beak emerging from the water, and they may "breach"; jumping partly or completely clear of the water and landing on the side of the body.

The South Asian River Dolphin feeds on a variety of shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 and fish, including carp
Carp
Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain...

 and catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

. They are usually encountered on their own or in loose aggregations; the dolphins do not form tight interacting groups.

Conservation


International trade is prohibited by the listing of the South Asian River Dolphin on Appendix I of the Convention on International Trade in Endangered Species (CITES). It is protected under the Indian Wildlife Act, although these legislations require stricter enforcement.

Both subspecies are listed by the IUCN as endangered on their Red List of Threatened Species. The Indus River Dolphin is listed as endangered by the U.S. government National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...

 under the U.S. Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

. On a positive note, in recent years the population of Blind Indus Dolphins in Pakistan has increased.

The immediate danger for the resident population of P. gangeticus in National Chambal Sanctuary is the decrease in river depth and appearance of sand bars dividing the river course into smaller segments. The proposed conservation measures include designated dolphin sanctuaries and the creation of additional habitat.

The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.

The Uttar Pradesh government in India is bringing up 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 Ramayan, highlighted the force by which the Ganga emerged from Lord Shivji’s locks and along with this force came many species such as animals, fish and the Shishumaar—the dolphin.

Human interaction


Both subspecies have been very adversely affected by human use of the river systems in the sub-continent. Entanglement in fishing nets can cause significant damage to local population numbers. Some individuals are still taken each year and their oil and meat used as a liniment, as an aphrodisiac
Aphrodisiac
An aphrodisiac is a substance that increases sexual desire. The name comes from Aphrodite, the Greek goddess of sexuality and love. Throughout history, many foods, drinks, and behaviors have had a reputation for making sex more attainable and/or pleasurable...

 and as bait for catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

. Irrigation has lowered water levels throughout both subspecies' ranges. Poisoning of the water supply from industrial and agricultural chemicals may have also contributed to population decline. Perhaps the most significant issue is the building of more than 50 dams along many rivers, causing the segregation of populations and a narrowed gene pool
Gene pool
In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...

in which dolphins can breed. There are currently three sub-populations of Indus Dolphins considered capable of long-term survival if protected.

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