The Odisha coast is very famous for dolphins which attract tourists from far and wide. Their habitat in the State's coast is very congenial, but over some years the conditions are degrading very fast due to various reasons, particularly for commercialisation of the ocean and pollution of the habitat.
A recent census of the dolphins speaks that the management of the habitat of oceanic creatures, particularly of the flora and fauna, is not up to the mark. Dolphin is a mammal. There are various types of dolphins, but in Odisha, the Gangetic dolphin is very common. The biological name of the species is "Platanista gangatica". There are also various types of this Gangetic one; which is known as Irrawaddy dolphin, Bottle nose dolphin and Humpback dolphin.
The Irrawaddy is the main river of Myanmar, which enters to the Andaman sea. In Sanskrit and Odia it is known as Sisumar. Generally, it grows up to 2.3 to 2.6 mtr in length. The females are larger than the males. The head is prolonged with a compressed beak. The number of teeth varies from 27 to 32 in each side of jaw. This species is found in the Ganges, the Brahmaputra, the Indus and their tributaries. But it never enters into deep sea. The Gangetic dolphins always move in small groups. The animal always avoids the hotness of the climatic conditions and migrates to comfortable zones. The governing factors of migration are food, temperature, increased salinity in the oceanic water and pollution of habitat. It always rises to the surface of the water body for breathing and lives upon the crustaceans and cat fishes, which live generally in bottom of the bays. During monsoon months, the Gangetic dolphin commonly descends to the tidal waters. Quite often for this reason, the dolphins are caught in the fishing nets. The gestation period of dolphin is nine months. The young are born between April and July. This is the best period for census.
Poaching is a prominent factor for quick reduction in number. The nets and the harpoons are used for capturing the animals. The oil of the animal is used for different kinds of medicines and purposes. There is no great zoological difference between the Indus dolphin and Gangetic dolphins, although these animals are described as separate species. The Indus dolphin is known scientifically as "Platanista indi", but the Gangetic dolphin is known zoologically as "Platanista gangetica". Both are marine cetacean and ranks with the other fresh water dolphins.
The group of dolphins is known as a school. There is always cooperation between the members of a school to help each other. The main food of the dolphin is the shoaling fishes and krills. The main and vulnerable zones of availability of dolphin in Odisha are Gahirmatha river mouth, Brahmani, Baitrani, Dhamara and Chilika. The river mouth of various river streams; Hukitola, the river mouth of Mahanadi, Paradip coast, Bhitarakanika, Kalibhajadia, Chanjirily Muhan, Jatadhari Muhan, Kajalapatia, Nalitapatia, Jambu, Kharnashi etc. are places known as hub of dolphins in North -Eastern coast of Odisha. The Subarnrekha river is the main route of dolphins, which joins the Bay of Bengal within the State of Odisha crossing the boundary of West Bengal.
As informed, a total 307 dolphins are counted to be living in Odisha side, but the details of sex and age are not known. The counting of dolphin or any other mammals of the oceaning creatures are done only on sighting. These are migratory animals. They migrate from one place to other for food and for peaceful existence.
During rains, the dolphins in pair are found in the Budhabalanga river. The river originates from Similipal hills of the Eastern Ghat range. The wild life wing of Odisha State Forest Department is carrying out a census of dolphins since 1915, but the census should be carried out at a time throughout of the State, where there is possibilities of presence of dolphins on migration.
Chilika is a most vulnerable lagoon at present. Now, the entire wetland stands polluted due to commercial exploitation of the lagoon resources. So conservation measures are required to maintain the ecological order of the nature. Every river mouth is very rich in bio-diversities of flora and fauna. The problem is that large scale fishing is carried out within the river mouths creating problems for the very existence of all kinds of oceanic mammals. The oceanic mammals are voracious eaters. They need profuse food for survival. Sometimes, they eat plastic products along with their normal food and die due to food poisoning. It is not unusual that, we get several bodies of dolphins and other oceanic mammals in the sea coasts of Odisha and other States due to plastic poisoning and other such oceanic poisoning. There should be greater awareness among the people for preventing oceanic pollutions.
Odisha has nearly 500 km of sea coast which forms the north- eastern and southern boundary of the State; but there is no consciousness for conservation and protection of the sea and the coast. The students are not taught on the benefits we normally get from ocean.
Basically, the whole ocean is divided in to four zones right from surface of the ocean to bottom. Such divisions are the sun-lit zone, the twilight zone, the dark zone and the abyss zone. The sunlight zone is the most important zone of all. It extends to a depth of 650 feet. In this zone there is enough of sun light to promote the growth of various types green plants. There are strong food chains in this zone to maintain the biodiversity. The sun light zone is known as the home of dolphins and other mammals of the ocean. The sun lit zone is the life of the ocean. If the zone is spoiled through commercial activities and other types of pollutions then the whole food chains of land and ocean will be seriously affected. The writer recently visited Chilika lagoon, but did not come across any dolphin. The local people are also not seeing dolphins any more, which means their population is on the wane.
(The writer is an ex-forest officer and an environmentalist, Mob: 9937460649, Email: nadiya.kanungo@gmail.com)