Ganges river dolphin Platanista gangetica
They were found in large numbers before a few years. But now their number has come down considerably due to various human activities like fishing (gillnetting), poaching, damming (Farakka barrage) in Ganges and other dams, sand mining (in Kulsi river of Assam) and deforestation.
The river dolphins are included in the schedule 1 of Indian Wildlife Act 1972. According to this Act, if any one is found killing them or possessing any part of them can be imprisoned for 1-6 years and fined not less than Rs. 6000.
The Ganges river dolphins ("Susu" or "Hihu") grow to a maximum length of 2.6 m (8 ft.), weighing about 100 kg. They have elongated beak with about 28 sharp curved teeth on each side of upper and lower jaws. The flippers (fore arms) are broad and paddle like. The dorsal fin is short but the caudal fluke is well developed. As they are mammals they breath air with lungs and come to the surface for breathing. They have to surface at least once in 30-50 seconds. They give birth to a calf of length of about 65 cm after a gestation period of about 9 months. They feed their young ones with milk from the mammary glands located near its anus. The river dolphins feed on small fishes and prawns. They mature at an age of 6-7 years and may live for about 35 years. Because of their poor eye sight they cannot be trained as in the case of marine dolphins. Further they do not live for long in captivity. Hence they cannot be kept for shows in dolphinariums.
The uniqueness of the dolphin is their highly developed sonar sense. It is the only aquatic mammal which has developed its sonar sense (sound ) to an extent that it captures its food and navigates with the help of echolocation. They produce ultra sonic sound upto 200 000 Hz where as the hearing capacity of the human ear is only 18 000 Hz. Its optic sense organs have degenerated and their eye lens have atrophied. But the loss of vision is compensated by the well developed sonar sense.
During a recent population
survey conducted in 1993 from South Salmara to
It is estimated that about 100 dolphins are killed annually in Ganges and Brahmaputra. The oil of dolphins is used as medicine for rheumatism and for the preparation of bait for the catfishes, Clupisoma garua (Garuah fish or Neria). Bihari and Bangladesh fishermen carry out the fishery in Brahmaputra. It has been recently found that the fish oils can be used in the place of dolphin oil for the preparation of bait. Popularisation of the fish oil as bait may reduce the poaching of dolphins for its oil. Crude shark liver oil was distributed to the fishermen of South Salmara, Dhubri and Goalpara and the results were very encouraging. It was observed that the fishermen of Dhubri and Goalpara in Assam, and Kahalgan of Bihar in Ganges were getting more fishes when they used the bait made of fish oil than with dolphin oil. Further River Dolphin Protection Committees are formed in the districts along the banks of the Brahmaputra with Deputy Commissioners as Patrons and officials and interested individuals as members. These committees will be taking active role in protecting the species.
R.S. Lal Mohan surveying river
Brahmaputra for river dolphinsThough the river dolphins of Ganges and Brahmaputra are in peril, they can be saved, if concrete efforts are taken. The survival of the species rests finally in the hands of fishermen, who are unfortunately, poor and illiterate. Any steps directed to save the dolphins should take into consideration their economic status and give them an alternate livelihood.
Banning the use of dolphin oil as a fish bait, popularisation of fish oil as bait, implementation of Indian Wildlife Protection Act, 1972, improving the habitat of dolphins, prevention of over-exploitation of fish stock, declaration of sanctuaries (Kulsi river and lower reaches of Subansiri river) and creation of general awareness among fishermen and law enforcing authorities will go a long way in saving this endangered and unique river dolphins of Ganges and Brahmaputra.
Read more in the
book: Whales and Dolphins of India, by R.S. Lal Mohan
For more information contact:
Phone +91-(0)4652-35 027
(c) Dr. R.S. Lal Mohan, last updated Oct.. 2000, firstname.lastname@example.org
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