Indus river dolphin

Dolphin species found in the Indus River

Indus river dolphin

Size compared to an average human

Conservation status

Endangered (IUCN 3.1)[1]

CITES Appendix I (CITES)[1]

Scientific classification
Kingdom:  | Animalia
Phylum:  | Chordata
Class:  | Mammalia
Order:  | Artiodactyla
Suborder:  | Whippomorpha
Infraorder:  | Cetacea
Family:  | Platanistidae
Genus:  | Platanista
Species:  |

P. minor

Binomial name
Platanista minor

Owen, 1853

Ranges of the Indus river dolphin and Ganges river dolphin

The Indus river dolphin (Platanista minor) is a species of freshwater dolphin in the family Platanistidae. It is endemic to the rivers of the Indus basin in Pakistan and northwestern India.[1] This dolphin was the first discovered side-swimming cetacean. In Pakistan, it occurs in the Indus river, patchily distributed in five small sub-populations that are separated by irrigation barrages. In India, a very small isolated population at a very high risk of extinction lives in the Beas river.

From the 1970s until 1998, the Ganges River dolphin (Platanista gangetica) and the Indus dolphin were regarded as separate species; however, in 1998, their classification was changed from two separate species to subspecies of the South Asian river dolphin. However, more recent studies support them being distinct species. It is listed as the national mammal of Pakistan and the state aquatic animal of Punjab, India.

## Taxonomy

[edit]

The long jaws and deep brain pan of the Indus river dolphin are visible from this skull cast. From the collection of The Children's Museum of Indianapolis.

The Indus river dolphin was described in 1853 by Richard Owen under the name Platanista gangetica, var. minor, based on a dolphin skull, which was smaller than skulls of the Ganges river dolphin.[2]

The Indus and Ganges river dolphins were initially classified as a single species, Platanista gangetica. In the 1970s, they were considered to be distinct species, but again grouped as a single species in the 1990s. However, more recent studies of genes, divergence time, and skull structure support both being distinct species.[3]

The Ganges river dolphin split from the Indus river dolphin during the Pleistocene, around 550,000 years ago.[4]

## Description

[edit]

Dolphins leaping

The Indus dolphin has the long, pointed nose 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, although it may still be able to detect the intensity and direction of light. Navigation and hunting are carried out using echolocation. The body is a brownish color and stocky at the middle. The species has a small triangular lump in place of a dorsal fin. The flippers and tail are thin and large in relation to the body size, which is about 2–2.2 m (6 ft 7 in – 7 ft 3 in) in males and 2.4–2.6 m (7 ft 10 in – 8 ft 6 in) in females. The oldest recorded animal was a 28-year-old male 199 cm (78 in) in length.[5] Mature adult females are larger than males. Sexual dimorphism is expressed after females reach about 150 cm (59 in); the female rostrum continues to grow after the male rostrum stops growing, eventually reaching approximately 20 cm (7.9 in) longer.[citation needed]

## Distribution

[edit]

The Indus river dolphin presently only occurs in the Indus River system.[1][6] Its range once stretched over about 3,400 km (2,100 mi) of the Indus River and its tributaries, but today, it only occurs in about 690 km (430 mi) of the river, and its range has declined by 80% since 1870; it is not present anymore in the tributaries.[6] A remnant population is present in the Beas River and Harike Wetland located in Punjab, India.[7][8]

Since the two originally inhabited river systems – between the Sukkur and Guddu barrage in Pakistan's Sindh Province, and in the Punjab and Khyber Pakhtunkhwa Provinces – are not connected in any way, how they were colonized remains unknown. The river dolphins are unlikely to have travelled from one river to another through the sea route, since the two estuaries are very far apart. A possible explanation is that several north Indian rivers such as the Sutlej and Yamuna changed their channels in ancient times while retaining their dolphin populations.[9]

## Behaviour and ecology

[edit]

It is thought that the Indus river dolphin swims on its side to efficiently navigate shallow waters during the dry season.[10]

## Threats

[edit]

Illustration by Friedrich Specht

The Indus river dolphin has been very adversely affected by human use of the river systems in the subcontinent. Entanglement in fishing nets can cause significant damage to local population numbers. Some dolphins are still caught each year for their oil and meat that is used as a liniment, as an aphrodisiac and as bait for catfish. Irrigation has also lowered water levels throughout their 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 dozens of dams along many rivers, causing the segregation of populations and a narrowed gene pool in which dolphins can breed. There are currently three sub-populations of Indus dolphins considered capable of long-term survival if protected.[6]

## Conservation status

[edit]

The Indus river dolphin is protected under Appendix I of the Convention on the International Trade of Endangered Species which prohibits the commercial international trade of the species (including parts and derivatives).[6] It is listed as Endangered on the IUCN Red List,[1] and by the U.S. government National Marine Fisheries Service under the U.S. Endangered Species Act. It is the second most endangered cetacean in the world. As of 2017 it is estimated that there are only about 1,800 individuals remaining (up from 1,200 estimated in 2001).[11] A demonstrable increase in the main river population of the Indus subspecies between 1974 and 2008 may have been driven by permanent immigration from upstream tributaries, where the species no longer occurs.[12] According to an estimation survey conducted by the Wildlife Institute of India, there are only three individuals found in the Beas River.[13][14]

It is threatened by extensive fishing that reduces their prey availability.[15] Accidentally entangling in fishing nets causes fatalities.[16] Deforestation along the river basins is causing sedimentation which degrades the dolphin's habitat.[15] Another factor for its decline is the construction of cross-river structures such as dams and barrages causing more isolation of the already small sub-populations.[15] A major threat is human induced water pollution through industrial and human waste, or agricultural run-off containing high amounts of chemical fertilizers and poisonous pesticides.[15]

Studies suggest that a better understanding of this species ecology is needed in order to develop good conservation plans. Regular monitoring is necessary to assess the population's status and factors causing its decline.[15] A satellite tagging effort was begun in 2022.[17]

## See also

[edit]

* South Asian river dolphin
* Project Dolphin (India)
* Amazon river dolphin

## References

[edit]

1. ^ a b c d e Braulik, G.T.; Khan, U.; Malik, M. & Aisha, H. (2023) [errata version of 2022 assessment]. "Platanista minor". IUCN Red List of Threatened Species. 2022: e.T41757A243168232. doi:10.2305/IUCN.UK.2022-1.RLTS.T41757A243168232.en. Retrieved 4 March 2024.
2. ^ Braulik, G.T.I.; Archer, F.; Khan, U.; Imran, M.; Sinha, R.K.; Jefferson, T.A.; Donovan, C. & Graves, J.A. (2021). "Taxonomic revision of the South Asian River dolphins (Platanista): Indus and Ganges River dolphins are separate species". Marine Mammal Science. 37 (3): 1022–1059\. Bibcode:2021MMamS..37.1022B. doi:10.1111/mms.12801. hdl:10023/21691.
3. ^ "Explore the Database". www.mammaldiversity.org. Retrieved 2021-08-27.
4. ^ "Fossilworks: Platanista gangetica". Archived from the original on 2023-04-22. Retrieved 2021-12-17.
5. ^ Kasuya, T., 1972. Some information on the growth of the Ganges dolphin with a comment on the Indus dolphin. Sci. Rep. Whales Res. Inst. 24: 87–108.
6. ^ a b c d Braulik, G.T. (2006). "Status assessment of the Indus river dolphin, Platanista gangetica minor, March–April 2001". Biological Conservation. 129 (4): 579–590\. Bibcode:2006BCons.129..579B. doi:10.1016/j.biocon.2005.11.026.
7. ^ Puri, G. (2022). "Tarn Taran diary: Harike, an abode for birds, rare Indus dolphins". The Tribune.
8. ^ Mahale, S. (2024). "Indus river dolphins in troubled waters". Mongabay India.
9. ^ Sanyal, S. (2012). Land of the Seven Rivers: A Brief History of India's Geography. Penguin.
10. ^ Herald, E. S.; Brownell, R. L.; Frye, F. L.; Morris, E. J.; Evans, W. E.; Scott, A. B. (1969). "Blind river dolphin: first side-swimming cetacean". Science. 166 (3911): 1408–1410\. Bibcode:1969Sci...166.1408H. doi:10.1126/science.166.3911.1408. PMID 5350341.
11. ^ "Signs of hope as population of endangered Indus River dolphin jumps in Pakistan". WWF. Retrieved 2017-12-17.
12. ^ Braulik, G. T.; Noureen, U.; Arshad, M.; Reeves, R. R. (2015). "Review of status, threats, and conservation management options for the endangered Indus River blind dolphin". Biological Conservation. 192: 30–41\. Bibcode:2015BCons.192...30B. doi:10.1016/j.biocon.2015.09.008.
13. ^ "What the first-ever comprehensive survey of India's river dolphins revealed". The Indian Express. 2025-03-04. Retrieved 2025-03-13.
14. ^ "Population Status of River Dolphins in India". wii.gov.in. Retrieved 2025-03-13.
15. ^ a b c d e "Indus River dolphin: the survivor of River Beas, Punjab, India". India Biodiversity Portal. Retrieved 2021-08-27.
16. ^ Khan, M.S. (2013). "Indus River Dolphin: The Survivor of River Beas, Punjab, India". Current Science. 104 (11): 1464–1465.
17. ^ "First ever satellite tagging of river dolphins in Asia". WWF. 2022. Retrieved 2 February 2022.

## Further reading

[edit]

* Randall R. Reeves; Brent S. Stewart; Phillip J. Clapham; James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0-375-41141-0.

## External links

[edit]

Wikimedia Commons has media related to Platanista minor.

* v
* t
* e

Extant Cetacea species

* Kingdom Animalia
* Phylum Chordata
* Class Mammalia
* Infraclass Eutheria
* Superorder Laurasiatheria
* Order Artiodactyla
* Suborder Whippomorpha

Parvorder Mysticeti (Baleen whales)

| Balaenidae|

| Balaena|

* Bowhead whale (B. mysticetus)

|

Eubalaena
(Right whales)|

* Southern right whale (E. australis)
* North Atlantic right whale (E. glacialis)
* North Pacific right whale (E. japonica)

Balaenopteridae
(Rorquals)|

| Balaenoptera|

* Common minke whale (B. acutorostrata)
* Antarctic minke whale (B. bonaerensis)
* Sei whale (B. borealis)
* Bryde's whale (B. brydei)
* Pygmy Bryde's whale (B. edeni)
* Blue whale (B. musculus)
* Omura's whale (B. omurai)
* Fin whale (B. physalus)
* Rice's whale (B. ricei)

|

Eschrichtius|

* Gray whale (E. robustus)

Megaptera|

* Humpback whale (M. novaeangliae)

Cetotheriidae|

| Caperea|

* Pygmy right whale (C. marginata)

|

Parvorder Odontoceti (Toothed whales)

| Delphinidae
(Oceanic dolphins)|

| Aethalodelphis|

* Pacific white-sided dolphin (A. obliquidens)
* Dusky dolphin (A. obscurus)

|

Cephalorhynchus|

* Peale's dolphin (C. australis)
* Commerson's dolphin (C. commersonii)
* Hourglass dolphin (C. cruciger)
* Chilean dolphin (C. eutropia)
* Heaviside's dolphin (C. heavisidii)
* Hector's dolphin (C. hectori)

Delphinus|

* Common dolphin (D. delphis)

Feresa|

* Pygmy killer whale (F. attenuata)

Globicephala
(Pilot whales)|

* Short-finned pilot whale (G. macrorhynchus)
* Long-finned pilot whale (G. melas)

Grampus|

* Risso's dolphin (G. griseus)

Lagenodelphis|

* Fraser's dolphin (L. hosei)

Lagenorhynchus|

* White-beaked dolphin (L. albirostris)

Leucopleurus|

* Atlantic white-sided dolphin (L. acutus)

Lissodelphis
(Right whale dolphins)|

* Northern right whale dolphin (L. borealis)
* Southern right whale dolphin (L. peronii)

Orcaella|

* Irrawaddy dolphin (O. brevirostris)
* Australian snubfin dolphin (O. heinsohni)

Orcinus|

* Orca or killer whale (O. orca)

Peponocephala|

* Melon-headed whale (P. electra)

Pseudorca|

* False killer whale (P. crassidens)

Sotalia|

* Tucuxi (S. fluviatilis)
* Guiana dolphin (S. guianensis)

Sousa
(Humpback dolphins)|

* Indo-Pacific humpback dolphin (S. chinensis)
* Indian Ocean humpback dolphin (S. plumbea)
* Australian humpback dolphin (S. sahulensis)
* Atlantic humpback dolphin (S. teuszii)

Stenella|

* Pantropical spotted dolphin (S. attenuata)
* Clymene dolphin (S. clymene)
* Striped dolphin (S. coeruleoalba)
* Atlantic spotted dolphin (S. frontalis)
* Spinner dolphin (S. longirostris)

Steno|

* Rough-toothed dolphin (S. bredanensis)

Tursiops
(Bottlenose dolphins)|

* Indo-Pacific bottlenose dolphin (T. aduncus)
* Burrunan dolphin (T. australis)
* Tamanend's bottlenose dolphin (T. erebennus)
* Common bottlenose dolphin (T. truncatus)

Monodontidae|

| Delphinapterus|

* Beluga whale (D. leucas)

|

Monodon|

* Narwhal (M. monoceros)

Phocoenidae
(Porpoises)|

| Neophocoena
(Finless porpoises)|

* Indo-Pacific finless porpoise (N. phocaenoides)
* Yangtze finless porpoise (N. asiaeorientalis)
* East Asian finless porpoise (N. sunameri)

|

Phocoena|

* Spectacled porpoise (P. dioptrica)
* Harbour porpoise (P. phocoena)
* Vaquita (P. sinus)
* Burmeister's porpoise (P. spinipinnis)

Phocoenoides|

* Dall's porpoise (P. dalli)

Physeteridae|

| Physeter|

* Sperm whale (P. macrocephalus)

|

Kogiidae|

| Kogia|

* Pygmy sperm whale (K. breviceps)
* Dwarf sperm whale (K. simus)

|

Iniidae|

| Inia|

* Araguaian river dolphin (I. araguaiaensis)
* Bolivian river dolphin (I. boliviensis)
* Amazon river dolphin (I. geoffrensis)

|

Lipotidae|

| Lipotes|

* Baiji (L. vexillifer)

|

Platanistidae|

| Platanista|

* Ganges river dolphin (P. gangetica)
* Indus river dolphin (P. minor)

|

Pontoporiidae|

| Pontoporia|

* La Plata dolphin (P. blainvillei)

|

Ziphiidae
(Beaked whales)|

| Berardius|

* Arnoux's beaked whale (B. arnuxii)
* Baird's beaked whale (B. bairdii)
* Sato's beaked whale (B. minimus)

|

Hyperoodon
(Bottlenose whales)|

* Northern bottlenose whale (H. ampullatus)
* Southern bottlenose whale (H. planifrons)

Indopacetus|

* Tropical bottlenose whale (I. pacificus)

Mesoplodon
(Mesoplodont whales)|

* Sowerby's beaked whale (M. bidens)
* Andrews' beaked whale (M. bowdoini)
* Hubbs' beaked whale (M. carlhubbsi)
* Blainville's beaked whale (M. densirostris)
* Ramari's beaked whale (M. eueu)
* Gervais's beaked whale (M. europaeus)
* Ginkgo-toothed beaked whale (M. ginkgodens)
* Gray's beaked whale (M. grayi)
* Hector's beaked whale (M. hectori)
* Deraniyagala's beaked whale (M. hotaula)
* Strap-toothed whale (M. layardii)
* True's beaked whale (M. mirus)
* Perrin's beaked whale (M. perrini)
* Pygmy beaked whale (M. peruvianus)
* Stejneger's beaked whale (M. stejnegeri)
* Spade-toothed whale (M. traversii)

Tasmacetus|

* Shepherd's beaked whale (T. shepherdi)

Ziphius |

* Cuvier's beaked whale (Z. cavirostris)

Taxon identifiers

Platanista minor|

* Wikidata: Q260018
* Wikispecies: Platanista minor
* ADW: Platanista_minor
* BOLD: 747352
* CoL: 6VNVD
* EoL: 1240173
* GBIF: 2440768
* iNaturalist: 1453948
* IRMNG: 11166812
* ITIS: 180414
* IUCN: 41757
* MDD: 1006547
* MSW: 14300135
* NCBI: 48752
* Paleobiology Database: 117088
* WoRMS: 254968

Platanista gangetica minor|

* Wikidata: Q12967430
* CoL: 7KLYH
* ECOS: 1231
* GBIF: 6165031
* iNaturalist: 147757
* ITIS: 612630
* NOAA: indus-river-dolphin
* Observation.org: 80609
* OBIS: 254969
* Paleobiology Database: 117087
* WoRMS: 254969

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