Blind Dolphin

Indus River Blind Dolphin 

  Physical Description

The South Asian River Dolphins have the long, pointed noses 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 colour and stocky at the middle. The species has only a small triangular lump in the 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 meters in males and 2.4-2.6 m in females. The oldest recorded animal was a 28 year old male 199 centimeters in length. Mature adult females are larger than males. Sexual dimorphism is expressed after females reach about 150 centimetres (59 in); the female rostrum continues to grow after the male rostrum stops growing, eventually reaching approximately 20 centimetres (7.9 in) longer. Calves have observed between January and May and do not appear to stay with the mother for more than a few months. Gestation is thought to be approximately 9–10 months.

The species feeds on a variety of shrimp and fish, including carp and catfish. Dolphins are usually encountered on their own or in loose aggregations; they do not form tight interacting groups.

Human interaction 

Both subspecies have been very adversely affected by human use of the river systems in the sub-continent. Entanglement in fishing nets can cause significant damage to local population numbers. Some individuals are still taken each year and their oil and meat used as a liniment, as an aphrodisiac and as bait for catfish. Irrigation has lowered water levels throughout both subspecies' 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 more than 50 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.

Both subspecies are listed by the IUCN as endangered on their Red List of Threatened Species. The Indus River Dolphin is listed as endangered by the U.S. government National Marine Fisheries Service under the U.S. Endangered Species Act.

The immediate danger for the resident population of P. gangeticus in National Chambal Sanctuary is the decrease in river depth and appearance of sand bars dividing the river course into smaller segments.          ,

By Yasir Babbar, Islamabad

Courtesy and Thanks: The News

Indus Blind Dolphin, a protected species, is fighting a war of survival in the Indus River because of record water shortage. The required water level in the reserve stretch of 210 kilometres for blind dolphin is at least 40 thousand cusecs. Only 10 to 15 thousand cusecs of water is currently available which makes breeding extremely difficult for the world renowned Indus Blind Dolphin.

It was after a research of about 40 years that the wildlife department found these dolphins between the Indus River’s Guddu and Sukkur Barrage area. At present there are 602 dolphins surviving in this stretch of the River Indus, declared as Indus Dolphin Reserve by the Sindh Wildlife Department way back in 1974. There is an Indus Dolphin Centre, established for its monitoring and safety, by the same department a few years ago.

Unfortunately, the authorities of Wildlife, Irrigation and IRSA have not made any more efforts to make the Indus Blind Dolphin (Andhi Bulhan) secure.

The Indus Blind Dolphin (Platanista minor) is one of the world’s rarest mammals and the second most endangered freshwater river dolphin. Endemic only to Pakistan, it is a close relative of Platanista Gangatica, which is found in India in the Brahmaputra and Ganga rivers. Historically, the Indus Blind Dolphin was found in abundance in the Indus River and its tributaries, mainly from the Himalayanfoothills (NWFP) to the delta region (Sindh) about a century ago. Its range was approximately 3,500 km of Indus River from upstream Attock to downstream delta region and the Sutlej, Ravi, Chenab and Jhelum rivers. At present, the potentially available habitat has shrunk to less than 900 km — mainly between Jinnah to Sukkur barrage.

Actually, the construction of dams and barrages on the Indus River has changed the distribution and movement of the Indus Dolphin and divided its current population into four or five subpopulations that exist in isolated pockets between these barrages and dams. The centre of abundance for the Indus Dolphin is currently in the area of Sindh.

Originally Platanista India was an inhabitant of the sea when the vast Indian subcontinent was submerged under the Tethys sea during the Eocene geological period. But as the land level rose and the sea dried up, the dolphins headed to adapt themselves to the new habitat provided by the turbid waters of the river. Adapting to the vastly changed environment cost them the loss of their sight. However, nature compensated the animal with the development of a perfect echolocation or sonar system. Thus, dolphins are able to navigate in the fierce current, find food and identify objects in the turbid waters of the river.

In view of the acute scarcity of water in the reserve area in Indus River and the consequent danger to the protected genus, TNS spoke to the Deputy conservator Wildlife Sukkur region Hussein Bux Bhaagat. “The water level in Indus River has been going down since 2005 and we are aware that Indus Blind Dolphin cannot survive in low level of water. Therefore I made many correspondences with the authorities of IRSA and irrigation departments but there is no response.” Bhaagat told that Indus Blind Dolphins can swim actively only when the water level is high and move freely up and down through the water currents in search of food .He appealed to the authorities of irrigation and IRSA to not create water shortage in Indus Dolphin Reserve between Guddu and Sukkur Barrages to save the species.

An environmentalist Nasir Ali Panhwar from IUCN told TNS that Indus Blind Dolphin is a typical fresh water mammal. The body is smooth, hairless, fish-shaped and pinkish gray in colour. The skin is devoid of mucous secretions and so delicate that it can be easily cut with a slight touch. He added that Dolphin has broad flippers and a long slender beak, which is comparatively shorter in the male than in the females. A fully grown, mature animal weighs between 100-120 kg and has a body length of about 170-176 cm and new born dolphins weighs 2-3kg and are 30-36cm in length. The animal breathes through a blow-hole located on the top of the head, which is directly connected to the lungs. Though virtually blind dolphin locates and identifies objects and prey by using a well-developed sonar system.

These animals prefer to live in groups near anchored boats and at the mouths of rivers and inundated canals. But the chances of fish disturbance are much more due to the frequent movements of boats. Nasir Panhwar explained that there are about //17 dolphin shoals between Guddu and Sukkur barrages. “Dolphins don’t stay permanently at a particular place but move from one place to another in search of food. At night, the dolphins come close to the fishing nets and boats to catch small fish, while during the day they prefer to stay at a distance from the boats because of human activity.”

He also told that Dolphins spend little time sleeping and mostly keep on the move in search of food. Adults surface every one to three minutes and calves 30-45 seconds to breathe through the blow-whole.

About the reproduction of Indus Blind Dolphins another environmentalist Amar Gurirro told TNS that the gestation period is about 11-12 months. After mating in April and May, breeding takes place in April-May in of the following year. He explained that Dolphins give birth to calves in shallow water no deeper than 0.5-1.5 meters, where water current is gentle. It is an observation by the experts that the birth process is rapid and the baby slips easily through the birth canal, tail first. The entire birth process takes place under the water. As soon as the baby is born, the mother quickly escorts the calf to the water surface to breathe deeply for the first time in air. The mother supports her baby with their flipper for about one and a half month and then releases the baby for the independent life like other baby dolphins.

Amar Gurirro told TNS that the Indus Blind Dolphin swims very fast to catch live fish. It holds the fish in its jaws at a right-angle to the beak, and swallows the whole fish, head first. During April and May when breeding takes place, dolphins are seen in shallow water. It is obvious that the mother dolphins easily find their prey by taking refuge in brush wood and other growth to feed their babies and themselves.

About the Dolphin a local fisherman Abdullah Mallah said while talking to TNS: “We used to catch fish in Indus River on a regular basis for many years. During this period we used to see dolphins in Indus River here in Sukkur barrage. He told that once a dolphin was caught in the net. When we saw, it was already dead. At that moment we were very disturbed because it was bad omen. I and my cousin Ali Sher also a fisherman buried the body of dolphin in the open land quite far from our homes.”

About the capture of dolphins by fishermen, the deputy conservator Hussain Bux Bhaagat told TNS that fishermen are illiterate so they don’t know about the significance of dolphins world wide. “We have charged such fishermen with fines etc and such incidents have not happened in recent times. We have extend the security system in Dolphin reserve zone.”