The Indus River dolphin is the world’s most infrequent mammals. It is the second most endangered freshwater river dolphin in the world. The Indus River dolphin, is a commit freshwater cetacean species found in the Indus River, Pakistan.
The common name Indus River dolphin are, Bhulan, blind river dolphin, Indus dolphin while the scientific name of Indus River dolphin Platanista minor. Round about 1,100 individuals of this species exist today in a small portion of their previous range, the lower number of the Indus River in Pakistan.The number of individuals in this species has continuously decreased due to different factors, such as water contamination, poaching, discontinuity of their habitat.
The numbers of dolphins have gradually declined since the construction of the water system framework in the Indus. This is the one of the main reason of their extinction. Approximately the number of individuals of Indus River dolphins are 965. According to the IUCN the status of Indus River dolphins is Endangered.
Indus river dolphin is endemic to Pakistan. They are found in the lower region, where the water current is weak, of Indus River in Pakistan. Its ecological regions are Indus River Delta & Rann of Kutch.The most favorable habitat of Indus River dolphin is of silt laden, fresh, turbid water with depth range 3-9 meter and temperatures range of 8-33 degree Celsius. They are mostly sighted in the main channel rather than secondary channel barrages.
Indus River Dolphin pattern of distribution is patchy. As it is native to Indus River Pakistan so it must be distributed throughout the Indus River, but it is now only found in waters below the Chasma, Trimmu, Islam and Sidhnai Barrages and water above the Kotri Barrages. Changes in rainfall pattern and threats poses by the human beings to them they now become limited to the small geographical area.
Diet mainly depends on the physical abilities and the area, which it lives. By using its echolocation abilities and long snouts combined with strong teeth they mostly live on other fish and invertebrates including prawns, catfish, carp, herring, masheers, gobies etc. By analyzing their stomach contents, it has been found that most important diet were Tank Gobi Glossogobius giuris, and freshwater prawns Macrobrachium rosenbergii and Macrobrachium malcolmsonii both of which are demersal and gregarious. The feeding is declined due to the summer monsoon as river bottom is fed by the flood resulting into erosion.
The unique behavior that was observed in Indus River dolphin was their side-swimming behavior. Pectoral flipper is trailed above or touch at the bottom, the tail was normally higher than the head, and the body nearly angled at 100 to the bottom and the head move side by side during the journey. The lower flipper has tactile function. It is mainly considered that they live solely but they generally they are found in groups but no more than three. They have poor eyesight perhaps they used the echolocation abilities for navigation and perception. But they used only 5% of these sounds for communication.
Due to the patchy distribution little is known about their reproduction but mostly they mate throughout the year as calves born at different season of the year. But in captive population it has been found that male chased the female in Spring season and their gestation period ranges from 8-11 months. At a time, it gives birth to only one newborn. Sexual maturity age for female and male is 10 years, less than 10 years respectively, and weaning age ranges between 2 to 12 months. No appropriate data available regarding their lifespan as their sexual maturity age is long so it has been predicted that these dolphins have longer lifespan approximately 28 years.
As each dolphin eat a kilogram of benthic fish and invertebrates, yet it has not been clear that how much they affect prey population. People hunt them for meat and oil. While other just poach them as a fishing lure. Its oil is used for medicinal purposes and considered it as effective for aphrodisiac.
No adverse effects are being known but if these highly endangered species become extinct then there must be a negative impact on river ecosystem. If proper steps will not be taken toward their preservation, then Pakistan lost its unique dolphin specie.
Endangered species can be the cause of the great loss afterwards. Indus dolphin was highly found under the area included in the subcontinent but in the 1930’s the construction the dams and barrages cause a great damage to them it disturbed their habitat and because of this they started migrating and this was also a cause of death for them. Some people caught them and sale their flesh and oil for their personal benefits. Increase in the human population was also a great cause of damage for them because a huge level of industry was held and a high range of chemicals were discharged on the river kitchen utensils were being washed with the river water was also effecting the specie badly in 1879. Anderson reported that in different areas he found hunting of the dolphin for flesh and oil. The oil of the dolphin in used in medicines and to produce light and same thing was reported in 1900 and 1915 some Muslims were also found eating its flesh somehow it is considered as haram in Islam and a huge amount of the non-Muslims were using it as their food. In 1970 by survey it was found that Muslims don’t have it any more but non-Muslims still in 1970 there was an action done for it, hunting of dolphins were banned due to this its population become stable with the passage of the time. After the time the Pakistan came into being there was a rule passed for it and any kind to damage to this specie was strictly banned and this later give the positive result.
Through a community based conservation approach, WWF along with Sindh Agriculture Extension Department is taking the following steps for conservation of Indus River dolphin.
- In order to reduce the pollution agricultural practices are being improved.
- WWF educates the anglers regarding its ecological role and importance.
- WWF rescued 80 dolphins from irrigation canals.
- By organizing Dolphin Safaris ecotourism has been promoted among the public.
- Scientific research has been conducted in order to understand its habitat and its ecological role.
Research and Report by: Bareera Anees, Qurat-Ul-Ain Rahman & Adeen Raees
Under the supervision of: Dr. Sahar Fazal