Mammals of Ganga
The otters, at the apex of the food web, are good indicator species of health status of different aquatic ecosystems they inhabited. India is the home of three species viz; Common otter Lutra lutra, smooth coated otter Lutra perspicillata, and the small-clawd otter Aonyx cinerea.
Conservation Of Dolphin
They are members of a large mammalian family called Mustelidae. With their shy and elusive habits, otters are extremely versatile, adapting to a variety of habitats, ranging from marine to freshwater environments. They are invariably associated with water, with a few exceptions. Otters are mainly active around dawn and dusk, being what is known as crepuscular. However; in areas with lower levels of disturbance, they often tend to remain active during anytime of the day.
All the species have been protected under the Wildlife (Protection) Act, 1972 and are listed as endangered. Eurasian and smooth coated otter are listed under Schedule II while Small-clawed otter is listed under Schedule I, which provide complete protection from hunting. Also, Eurasian otter is listed in Appendix I and; smooth coated and small-clawed otter are listed in Appendix II on CITIES. On the other hand, Smooth-coated and Oriental Small-clawed otter are placed in vulnerable category, while Euratian otter is placed in near threatened category by IUCN, 2010.
Smooth Coated Otter (Lutra perpicillata) in the Gangetic plain:-
• Kingdom – Animalia
• Phylum – Chordata
• Class – Mammalia
• Order – Carnivora
• Family – Mustelidae
• Sub Family – Lutrinae
• Genus – Lutrogale
Distribution:- The smooth-coated otter is distributed throughout southern Asia from Indonesia, through Southeast Asia, and westwards through southern China, India and Pakistan, with an isolated population in Iraq. It is gregarious often found in large groups of 4-16 otters. In the wild, the basic family group consists of adult female and her offspring, father and older siblings often join the group, however occasionally two to three family groups join together for hunting. Though the distribution range is known NO detailed population assessment has been done and there is no data available on the number of otters in India. There has also been no recent study on the distribution range reaffirmation either.
Habitat :- The smooth-coated otter essentially is a lowland species. Generally, they use large rivers and lakes, peat swamp forests, mangrove forests along the coast and estuaries. Along the rivers, they prefer rocky stretches since these stretches provide sites for den and resting. They extensively use river banks and shorelines with vegetation for movement and resting. In the Terai areas of the upper Gangetic plains smooth-coated otters use the seasonally flooded swamps during monsoon and in early winter.
Major Threats:- Otters are considered the “ambassadors of the wetlands”. Their presence is the best indicator of the health of the wetland’s ecosystem. However, rampant poaching and habitat destruction threaten the future of otters in India.
Habitat Destruction:- Otters prefer sandy and rocky shores of rivers and marshy areas of wetlands, however due to developmental activities like Dams and Barrages and sand mining etc these areas are being destroyed at a very fast pace leaving no place for these otters.
Poaching:- Otter skins are used to decorate the traditional Tibetan costume, chuba. Otter heads are used to decorate the head gear worn during festivals and sports in Tibet. Water-proof otter skin is used to make fur coats in temperate regions. They are also used for outer lining of coats.
Ganges river dolphin (Platanista gangetica gangetica):-
Two species of River dolphins; the Ganga river dolphin (Platanista gangetica gangetica) and the Indus river dolphin (P. gangetica minor) are found in the Indian subcontinent. The Ganga river dolphin, locally known as Susu, is restricted to the Ganga, Brahamputra, Karnaphuli- Sangu, and Meghna river systems and their tributaries, from the foot hills of the Himalaya to the limits of the tidal zone in India, Bangladesh, and Nepal. In Ganga River, dolphins are also present in its tributaries like Yamuna, Chambal, Ghaghra, Gandak, Rapti, Narayani and Kosi rivers.
• Class- Mammalia
• Sub-class- Eutheria
• Order- Cetacea
• Family- Platanistidae
• Genus- Platanista
• Species- gangeticus
• Sub-species- gangetica
Morphological characters:- The Ganges River dolphins have a long, pointed snout that is characteristic of all river dolphins. Both the upper and lower jaw sets of long sharp teeth are visible even when the mouth is closed. While the snout is long and widens at the tip, the female’s snout is generally longer than that of the male and may curve upwards and to one side. The eyes are extremely small openings slightly above the mouth. The species does not have crystalline eye lens rendering it effectively blind, although it may still be able to detect the intensity and direction of light. The body is a deep brown colour, stocky in the middle and attenuating to a narrow tail stalk behind the dorsal fin. The dorsal fin is a very low triangular hump located two-thirds of the body length from the anterior end. The broad flippers have a crenellated margin, with visible hand and arm bones. The flippers and flukes are thin and large in relation to the body size. Body size is about 2m - 2.2m in males and 2.4m - 2.6m in females. At the time of birth they measure 70cm - 90 cm and weigh around 6 kg. While adults usually weigh upto 120 kg.
Habitat and niche:- This species is exclusively riverine. Relatively high densities of dolphins are found at sites where rivers join or just downstream of shallow stretches, in areas where the current is relatively weak; off the mouths of irrigation canals; and near villages and ferry routes. In the river basins in India, the Ganga river dolphin is present mostly in plains where the rivers run slowly. This seems to be opposite to the habitat observed in Nepal, where the dolphin can be found in relatively clear waters and rapids. In both areas, however, there is a preference for deep waters. Primary habitats are characterized by an eddy countercurrent system in the main river flow caused by a fine sand/ silt point bar formed from sediment deposits of a convergent stream branch or tributary. Marginal habitats are characterized by a smaller eddy counter-current system caused by an upstream meander. Dolphins concentrate in locations of high prey availability and reduced flow.
In recent years several workers estimated the population of Ganga river dolphin in different segments of Ganga River and its tributaries in Ganga and Brahmaputra river system and Sundarbans delta. Once believed to be in the tens of thousands their number has gradually reduced to four to five thousand with a further decline to less than 2000 individuals in all the tributaries of its distribution range in India.
Breeding:- Dolphins are social animals and live in small to large groups, associated with many animals like crocodiles, turtles and wetlands birds. But in adulthood they turn solitary, remain alone or best in pairs, and may group during mating season where several males display courtship for the attention of the females. Calving apparently can occur at any time of the year, but there may be peaks in December to January and March to May. Newborn calves have been observed mainly in April and May. Calves are weaned within one year of birth. Gestation lasts 10-11 months.
Food and Feeding:- Dolphins are catholic feeders. Ganges river dolphins feed on several species of small fish and invertebrates ranging from 3.5-11.8 cm. They mostly feed at or near the bottom, echolocating and swimming on one side. The Ganga river dolphins show seasonal and diurnal migration for feeding and maintaining their territorial behavior. The marked seasonal changes in Susu distribution and density over much of its range at least in large part, are due to fluctuations in water levels. During the dry season from October to April, many dolphins leave the tributaries and congregate in the main channels, only to return to the tributaries the following rainy season. They may become isolated in pools and river branches during the dry season.
Status of dolphin in river Ganga:- The species is facing a series of threats for its survival due to poaching, construction of dams and barrages pollution; mining of sand and stones, and incidental catches in gillnets. The Ganga river dolphin is important not only because it is endangered, but perhaps more so because, it is a reliable indicator of the health of the Ganga river, in fact the whole river ecosystem. In spite of being a "flagship" species, representing an ecosystem in need of conservation, its status has become a matter of grave concern over the past few decades. This is why the government of India declared this animal as the “National Aquatic Animal”, during the year 2009. Close monitoring of dolphins and their habitats involving local communities is required for long term conservation of the species. It has been placed in Schedule-I of Wildlife (Protection) Act of India (1972). Appendix-1 reported in the Convention on International Trade in Endangered Species (CITES) (IUCN 2009) had listed the species as “Endangered”.
a) OM as on 28.10.2010.
b) OM as on 07.12.2012.
c) OM as on 18.12.2013.
National Aquatic Animals
a) National Aquatic Animals
The Gangatic Dolphin Report
a) The Gangatic Dolphin Report
Operatioonalization of Dolphin Action Plan,2010-2020
a) Operatioonalization of Dolphin Action Plan,2010-2020