Its call is hard to miss. A series of steady clicks, like switches being flipped on and off. To other marine life that move around in the water’s muddy depths, it is a sign that the Ganges river dolphin is nearby. Records dating back to 1879 show that the mammal once had a large range extending from the Himalayan foothills to the delta at the Bay of Bengal. It swam along the entire length of the Ganga and Brahmaputra, and their tributaries. Even during peak summer, when the levels of the Ganga were low, this dolphin could be seen even as far as the waters of the Yamuna in Delhi.
But things have taken a turn for the worse in the past few decades, with a decreasing trend in the population of the Ganges river dolphin. The construction of dams and water pollution caused by pesticides, fertilisers, and industrial effluents has resulted in a decline in their numbers. As per a 2018 National Mission for Clean Ganga (NMCG) report, their population in the river and its tributaries reduced from about 10,000 in the late 19th century to around 3,526 in 2014. The continued decline has prompted the IUCN Red List, which indicates global extinction risk status of species, to list it as “endangered”.
Today, it is estimated that 2,500-3,000 Ganges river dolphins survive in the wild. Of these, more than 80 percent can be found in the river Ganga and her tributaries. “The general population is on the decline. Some outliers may indicate otherwise. For instance, around 50 percent of the total freshwater dolphin population in the country can be found in Bihar alone, with the segment between Buxar and Manihari ghat having the maximum density. But yes, the overall numbers of the Ganges river dolphin have reduced over the years,” says Dr Bela Singh, who has been studying the species in Bihar for over two decades.
The Ganges river dolphin is endemic to the Indian subcontinent, and inhabits one of the most densely populated regions of the world. It is one of the four freshwater dolphin species in the world, the others being the Amazon river dolphin in South America, the Indus river dolphin in Pakistan and the Yangtze river dolphin in China (now thought to be extinct). It is almost blind, and depends on high-frequency clicks to catch prey, communicate with one another and navigate the muddy waters of the river systems it inhabits.
This species favours waters that are at least five feet deep, and prefers eddies around islands, river bends and confluences. The dolphins can typically be found in areas where there is little to no current. Doing so, helps them save energy. However, they head to more turbulent waters when it is time to feed, as they can find enough fish there. Once done hunting, they return to the no-current zone. Their diet is mainly made up of small and medium-sized fish, and crustaceans.
Often spotted alone, they at times can also form small groups. Females tend to be larger than males, and typically give birth to a single calf every two to three years. A calf is chocolate brown in colour, but develops grey-brown smooth skin as an adult. Mother and calf generally stay close, and travel together.
The Ganges river dolphin is an indicator species and has long been hailed by conservationists for the crucial role it plays in the ecosystem. “Its presence alone indicates the health of a river. They are top predators in their habitat, and play a role that is similar to the tiger in a forest,” says Vidyut Jha, independent researcher and marine biologist.
There are several threats to the dolphin’s population, the biggest being the declining flow in the Ganga due to the erection of dams and barrages. Also, water-intensive agriculture in the basin results in the base flow petering out, leading to fragmentation of their habitats.
That apart, industrial and human pollution has also led to degradation of their ecosystem. According to the World Wildlife Fund, annually, 9,000 tons of pesticides and 6 million tons of fertilisers are used in areas that are close to the river. It takes a toll on the dolphin and their prey species. They also get caught in fishing nets and are still killed for meat and oil, despite it being illegal to hunt or trade the species in international and domestic markets.
It is not all doom and gloom, though. Steps are being taken to ensure its long-term survival. In 2009, the government of India declared the Ganges river dolphin the ‘National Aquatic Animal’. This accords it equal status with the peacock, India’s National Bird, and the tiger, our National Animal.
When the 15,000 crore ‘Mission Clean Ganga’ project was announced at the same time, the then Environment and Forests Minister Jairam Ramesh acknowledged that an increase in the number of dolphins in the river would be the one and only yardstick to gauge its success. This has shown some results. As per the Uttar Pradesh government, as of 2022, there have been increased sightings of the mammal as the quality of water improves through the Namami Gange programme. Dolphins have also been seen breeding in Brijghat, Narora, Kanpur, Mirzapur and Varanasi, which will help their numbers in the future.
In 2020, a ‘Dolphin Jalaj Safari’ was started at six locations - Bijnor, Brijghat, Prayagraj and Varanasi in Uttar Pradesh, Kahalgaon (Bihar) and Bandel (West Bengal) - to help create awareness about the species, preserve the Ganga’s ecology and create employment opportunities for locals via tourism in the region. To protect and understand them better, Vikramshila Gangetic Dolphin Sanctuary and National Dolphin Research Centre have been set up in Bihar. A second research centre could be set up at the Katarniya Ghat Wildlife Sanctuary in Uttar Pradesh.
But more needs to be done. For instance, communities along vital stretches of dolphin habitat must be encouraged to use natural fertilisers and avoid disposal of domestic sewage in the river. The riverbank must also be reforested, and commercial fishing and sand-mining activities need to be controlled.
Conservation of this keystone species is essential and needs to be given the attention it deserves. “Failure to save it could have a cascading effect on the ecosystem and marine life that lives there in the long run,” says Singh.