Indus River Dolphin

*For Ganges river dolphin click here*

## About

An Indus river dolphin breaching.

The Indus river dolphin ***(Platanista minor)*** also known as the Bhulan, is a freshwater dolphin species that was once thought to be a subspecies of the Ganges river dolphin ***(Platanista gangetica)***. The Indus river dolphin is very similar in appearance to the Ganges river dolphin, both species possess pinkish-grey skin as well as a long beak. This beak contains spire-like teeth, that are noticeably very sharp. The eyesight of the Indus river dolphin is extremely poor, as they depend largely upon echolocation -having quite a large melon- to make their way around the murky Indus river. The weakened eyesight of platanistids is entirely due to the way the dolphins live, hunting in opaque waters that do not require good eyesight to navigate. Despite being very similar to the Ganges river dolphin, Indus river dolphins are unique in their physical features such as the dorsal ridge of the Indus river dolphin being much less pronounced, however, other features are almost identical between the species. Indus river dolphins can grow 2-2.5m (7-8.5ft) in length and weigh 90kg (200lbs) however, sizes may vary and females are generally larger than males.

## Diet

The Indus river dolphin has a majority piscivorous diet, eating species of fish. The dolphins are also known to sometimes form groups, hunting collectively in order to find clams and shrimp on the riverbed. The long beak of the Indus river dolphin is crucial to the way they hunt, allowing them to efficiently unearth prey items. Their fang-like teeth also allow greater dexterity, ensuring that prey cannot escape their maw.

## Conservation Status

Similarly to the Ganges river dolphin, the Indus river dolphin has been classed as an endangered species by the IUCN. Human activity in the Indus is the main reason for the species' decline, as the industrialisation of the river impacts the available habitat of the dolphin. The continued building of dams create problems for the dolphins, as they are typically built upstream from the dolphin's range. reducing the habitable areas of the Indus. These dams can reach up to 25m (82ft) in height on occasion, causing severe habitat fragmentation among populations. Often water is extracted from these areas for agricultural development, leading to further decline of habitat coupled with seasonal droughts. Projects such as the Indus Cascade Project, suggest the construction of six more dams on the China-Pakistan Economic Corridor, which is projected to have devastating effects on the dolphin's recovering population. The Punjab Spatial Strategy, also recommends the construction of inland waterways for the purpose of shipping, which further decreases the species' survivability rate. Human activity in the Indus has also lead to dolphins becoming trapped in irrigation canals. As Pakistan is a desert country, irrigation canals are essential to the agricultural industry in the country. Irrigation canals transport water from rivers into farmlands through riverways, and unfortunately since the 1990s, dolphins have been trapped in these canals for extended amounts of time. Indus river dolphins can often survive in these canals for months at a time however, once the waters are drained in Winter, the dolphins are left stranded, sometimes until death. 194 Indus river dolphin have been found in these canals from 1992-2022, and though 163 individuals were rescued, the remaining died, demonstrating the dangerous nature of these canals. Fishing apparatus such as gillnets are often left in the Indus overnight, which leads to dolphin casualties, as they can quite easily be ensnared in the nets. Bycatch deaths however, are only a small contributor to accidental killings of the Indus river dolphins, and a myriad of other factors play into their continued decline. Pollution in Indus has inadvertently contributed to dolphin casualties, as the contamination of the river causes health to decline in populations. Though the Indus is largely unpolluted, greater than 75% of the dolphin population occurs in the downstream Panjnab river, which contains the largest pollutants from the nearby cities of Punjab. As the Indus river is a high traffic zone for ships and motorised vessels, dolphins are often killed unintentionally by not only vessel collision, but also fisheries and bycatch. In fact, since 2008, 72 Indus river dolphin casualties have been attributed to net entanglement. Finally, Indus river dolphins were once often killed by locals for their meat and oil. These killings were traditional practices at the time, but after the 1970s, hunting had mostly ceased.

## Range and Population

The Indus river dolphin lives exclusively in the Indus river, which runs mostly in Pakistan, but is dolphins are also prominent in the northwestern Indian Beas river. Indus river dolphins inhabit deeper canals and are far less common in side canals, which are often more shallow. during the annual low-water season (October-April) the dolphins are typically diverted downstream by barrages, which flow large amounts of water into available dolphin habitat. Indus river dolphins are unable to inhabit river located at mountain foothills, as the rocky inclines create natural barriers which inhibit further upstream movement. Though the current population of the Indus river dolphin is small (currently sitting at 1,987 individuals) and occurs in fragmented habitat, the species is seeing a general population increase due to the continued effort of conservation methods such as legal protection. In recent years, the remaining dolphin population was protected, following the Wildlife Act of Sindh in 1972. In 1974, the government of Sindh would declare that the stretch of river between the Sukkur and Guddu barrages would now act as a dolphin reserve. The Punjab government would also prohibit the deliberate killing of dolphins in 1974, which has contributed greatly to population inclines, further decreasing chances of rapid decline in the population. These hunting regulations have proved to be extremely effective, as their have been no reports since of dolphin killing or dolphin oil and meat products. The declaration of the Taunsa and Chasma wildlife sanctuaries in 1983 and 1984 respectively have also become prime dolphin habitat and remain key biodiversity areas presently. One of the largest contributors to population incline has been the continued conservation efforts of the WWF. The dolphin canal rescue program established by the WWF has contributed to rescue of injured dolphins from canals for over 20 years, saving an average of 7 dolphins annually. WWF continues to work with the Sindh Wildlife Department, to rescue dolphins, continuing the canal rescue program as a partnership. With the legal protection of the species, the dolphins have become a more respected animal in the Indus, even becoming Pakistan's national mammal.

## Behaviour

Though pods of up to 30 individuals are reported, Indus river dolphins often do not exceed pod sizes of 3 individuals. Indus river dolphins are able to swim on their sides if needed, typically switching to this swimming method when restricted to shallow bodies of water. Interestingly, juveniles are unable to perform this style of swimming. Indus river dolphins were actually the first side-swimming dolphin ever discovered, first being described in 1853 by biologist Richard Owen. Unlike other dolphin species, Indus river dolphins do not perform the stereotypical aerial jumping (or breaching) that other dolphins do, preferring to stay submerged the majority of the time. Like other Cetaceans, Indus river dolphins employ a range of different vocalisations for a range of reasons. These vocalisations, known as echolocation, allow the dolphins to navigate their environments through the use of sounds. As Indus river dolphins are blind, echolocation greatly improves the animal's navigation. Unlike other dolphins however, Indus river dolphins will typically use echolocation more frequently for navigating murky rivers, rather than communicating with other individuals.

### Relationship with Humans

Indus river dolphins are shy animals that rarely approach humans. Dolphins will actively avoid motorised vehicles, which further drives them away from human interaction. Furthermore, noise pollution caused by industrialisation further inhibits the dolphin's navigation, causing the dolphins to avoid areas were humans are abundant. If noise pollution is frequent and loud enough, it can even cause temporary hearing loss and in more serious cases, it can even make dolphins go deaf.

## In Captivity

Due to the increased caution surrounding Cetacean welfare in captivity, Indus river dolphins do not occur in captivity.

## Sources

* Indus River Dolphin | NOAA Fisheries - https://www.fisheries.noaa.gov/species/indus-river-dolphin
* Indus River Dolphin | WWF - https://www.worldwildlife.org/species/indus-river-dolphin
* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/41757/50383490
* Indus River Dolphin | Animal Database University of Michigan, Museum of Zoology - https://animaldiversity.org/accounts/Platanista\_minor/
* Indus River Dolphin | Wikipedia - https://en.wikipedia.org/wiki/Indus\_river\_dolphin