Indus River dolphins
Indus River dolphins are a unique and endangered species of freshwater dolphins found in the Indus River of South Asia.
Its appearance is distinct from that of other dolphin species. It doesn’t have the same long beak as oceanic dolphins. Instead, its long, slender snout ends in a small, rounded mouth. The Indus River dolphin has a rounded body with a small triangular hump on its back, which is more pronounced in males. It has poor eyesight—which is likely due to the murky waters in which it lives—and relies on echolocation to locate its prey.
These dolphins are exclusively found in the waters of the Indus River in Pakistan, primarily inhabiting the lower reaches of the river, where the water is shallower and moves more slowly. Indus River dolphins are not known to exhibit aggressive hunting behaviours like their oceanic counterparts, and their diet primarily consists of fish, though they also feed on small invertebrates like clams and shrimp.
Indus River dolphins typically have a low reproductive rate. Females give birth to a single calf after a gestation period of around 9 to 10 months. Calves are born in late winter or early spring. Generally solitary animals, Indus River dolphins can sometimes be seen in loose, temporary groups. They are known for being cautious and shy. However, their social behaviours are not as well-documented as some other dolphin species due to their elusive nature.
Indus River dolphins are a valuable indicator species for the health of the Indus River. Their presence in the waterways indicates a thriving ecosystem, with sufficient food and water quality for the species to thrive. Protecting their habitat benefits a range of other aquatic species that also inhabit the river. The dolphins also help control the population of their prey, maintaining necessary ecological balance in the river.
Unfortunately, the Indus River dolphin is endangered due to habitat degradation, water pollution, and human activities like dam construction. Conservation efforts are essential to protect these unique and ecologically significant creatures as well as the overall health of the Indus River ecosystem.
What is the Indus River dolphin’s scientific name?
The scientific name for the Indus River dolphin is Platanista minor. They are toothed whales and part of the Platanistidae family.
Are Indus River dolphins endangered?
The species has been classed as endangered by the IUCN since 1986. With less than 2000 mature individuals left in the world, Indus River dolphins have a severely fragmented population and a declining mature population, making conservation efforts critical.
Indus River dolphins face several key threats, including:
- Habitat degradation: Dam construction and water diversion projects have altered the flow and quality of the Indus River, impacting the dolphins’ natural habitat.
- Water pollution: Industrial, agricultural, and domestic pollution have led to deteriorating water quality, affecting the health and food sources of the dolphins.
- Entanglement: Dolphins can become unintentional victims (known as bycatch) of fishing practices, getting caught in gillnets and other fishing gear.
- Climate change: Changing weather patterns and temperature fluctuations can impact the availability and quality of dolphins’ prey.
- Human activities: Human disturbances, including boat traffic and habitat destruction, disrupt the dolphins’ behaviour and habitat.
Where do Indus River dolphins live?
As evidenced by their name, Indus River dolphins live exclusively in the Indus River, which flows through South Asia. While their range used to extend from the river’s delta to the foothills of the Himalayas, they are now found in only 20% of that area, predominantly in the lower and middle areas of the river where it flows through south-central Pakistan.
Indus River dolphins inhabit the lower reaches of the river, favouring areas with slow-moving, murky waters.
Threats
Indus River dolphins face several threats, including entanglement, vessel strikes, industrial noise, habitat degradation, and pollution, which jeopardise the survival of the species.
Entanglement
With more than 180 species of fish available in the Indus River, it’s no surprise that fishing activity is high, particularly in the side channels and adjacent pools where fish live in abundance. Unfortunately, these fishing habits pose a significant threat to Indus River dolphins—they are often accidentally caught and entangled in fishing gear, such as gillnets and fishing lines, as they become bycatch.
Weighed down by fishing gear, entangled Indus River dolphins are unable to move freely through the water or feed. They are at risk of a slow, painful death. The fishing gear can also cut their bodies as they try to free themselves, potentially causing life-threatening damage.
Vessel strikes
High boat traffic on the Indus River can lead to collisions between Indus River dolphins and these large vessels, injuring or even killing the dolphins. The presence of boats also disrupts the dolphins’ natural behaviour and navigation, causing them to become disoriented.
Industrial noise
As they have poor eyesight, Indus River dolphins rely heavily on their other senses. However, increased industrial activities along the river contribute to underwater noise pollution, which can disrupt the dolphins’ echolocation and communication, making it harder for them to navigate and find prey.
Habitat degradation
The construction of dams, water diversion projects, and other building activities have altered the flow and water quality of the Indus River, impacting the dolphins’ natural habitat. Dams and irrigation systems are particularly problematic, as they stop Indus River dolphins from travelling freely upstream. This can cause populations to become fragmented, making it harder for the dolphins to reproduce.
Pollution
Industrial, agricultural, and domestic pollution have deteriorated the water quality in the Indus River, harming the dolphins’ reproductive and immune systems. These pollutants also impact the health—and number—of prey species, which in turn reduces the amount of food available to Indus River dolphins.
Climate change
As it does to many animals, climate change also poses a looming threat to Indus River dolphins. Changing weather patterns and temperature fluctuations can impact the availability and quality of prey species, which threatens the dolphins’ survival.
FAQs
What do Indus River dolphins look like?
These dolphins are 2 to 2.5 metres (6 to 8 feet) long and weigh 40 to 60 kilograms (90 to 130 pounds). Female Indus River dolphins are slightly larger than males.
The Indus River dolphin has distinctive physical features, including:
- A rounded, stocky body
- A small, triangular fin far down their back, which is more pronounced in males
- An elongated but slim snout with a small, rounded mouth, lacking the beak seen in marine dolphins
- Greyish-brown to pinkish skin, with a lighter underside
- Poor eyesight, due to their murky habitat
Their unique appearance is well-adapted to their freshwater habitat in the Indus River.
What do Indus River dolphins eat?
Scientists have observed that the diet of Indus River dolphins varies based on location and season, but generally consists of mid-sized bottom-dwelling fish, like catfish and carp, and invertebrates, like prawns and clams.
They use echolocation to locate and capture their prey in the Indus’ murky waters. The dolphins can hold their breath for several minutes, using their beak to scoop up food from the bottom of the river. Their reliance on fish as a food source is essential to maintaining the ecological balance of the Indus River ecosystem.
Are Indus River dolphins carnivores?
Indus River dolphins’ diets consist only of meat, making them carnivorous animals. They also have fang-like teeth that allow them to eat these meaty prey.
Are Indus River dolphins blind?
Due to its tiny eyes, located on each side of its head above its mouth, it’s widely believed that the Indus River dolphin is blind—or very close to blind.
Instead of relying on their eyesight to survive, they use sonar to navigate and find food. This echolocation method involves making high-pitched clicking sounds and listening for their reflections as they bounce off underwater objects. This technique allows them to determine an object’s size and density, how far away it is, how fast it’s moving, and in which direction it’s heading.
This echolocation is exceptionally precise, allowing dolphins to identify fish species by aiming their echolocation beams at different parts of their bodies. It’s so advanced that they can detect an object the size of a golfball from the length of a football pitch away.
Are Indus River dolphins mammals?
Like all other dolphin species, Indus River dolphins are mammals. Adults breed throughout the year, and females give birth to a single calf, which is nursed for around one year.
Do Indus River dolphins migrate?
Historically, Indus River dolphins moved upstream during the summer months—flood season—and returned downstream during the low-water season. However, in the last century, there have been a number of dams and barrages constructed that block the dolphins’ seasonal movements. It has impacted their quality of life and fragmented their population, making it harder for Indus River dolphins to find mates and reproduce.
Why is the Indus River dolphin endangered?
Indus River dolphins are endangered due to a combination of factors. Habitat degradation and alteration caused by dam construction, water diversion, and other human activities have significantly reduced their available habitat.
Pollution from industrial, agricultural, and domestic sources has led to deteriorating water quality, affecting both the dolphins’ and their prey’s health. Additionally, entanglement in fishing gear, vessel strikes, and boat traffic disrupt their behaviour and pose direct threats to their survival.
How many Indus River dolphins are left?
The exact number of Indus River dolphins left in the wild is estimated to be about 1,987. They are an endangered species.
How can you help?
IFAW is working hard to help save endangered species across the globe. To continue carrying out this important work, we require the generous support of animal lovers like you.