Marine Mammal Resources J. K. De Zoological Survey of India, Kolkata

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1 Marine Mammal Resources J. K. De Zoological Survey of India, Kolkata Marine mammals form a diverse group of 128 species that rely on the ocean for their existence. It includes seals, whales, dolphins and walruses. The level of dependence on the marine environment for existence, however varies considerably among different species e.g. Dolphins and Whales are completely dependent on the marine environment for all stages of their life, whereas seals feed in the ocean, but breed on land. They do not represent a distinct biological grouping, but rather are for feeding. Marine mammals can be categorised into Cetacea (whales, dolphins, porpises), Pinnipidea (seals, sea lions, walrus), Sirenia (manatees, dugongs), & Fissipedea (otter). The number of marine mammals is small compared to those found on land. Their total biomass is large and they play an important role in maintaining marine ecosystems through regulation of prey populations. These factors make them an integral component of the marine environment. Both Cetaceans and Sirenians are fully aquatic and so are obligate ocean dwellers. Pinnipeds are semi-aquatic & spend majority of their time in the water, but need to return to land for important activities such as mating and breeding. In contrast Fissipeds Otters are much less adapted to ocean living. Order Cetacea includes aquatic mammals having a fusiform body, a pair of pectoral flippers, a horizontally compressed tail-fluke with or without a notch in the middle, dorsal fin, absence of external hind limbs, teeth in one or both jaws (teeth replaced by baleen plates in few species), small eyes, nostrils (which open either separately or by a single crescentic hole much above the extremity of snout) and minute ear orifice. Examples Susuk, whale, dolphin. Order Sirenia includes massive, spindle shaped animals having paddle-like forelimbs, a horizontally flattened tail but no hind limbs or dorsal fin, tough hairless wrinkled skin, rounded head, abruptly cut-off muzzle, small mouth, separate and valvular nostrils located on upper surface of muzzle, small eyelids (capable of contraction with a well developed nictitating membrane, lack of external ears and highly modified and reduced dentition. e.g. dugong. What is Dolphin? Dolphins are aquatic mammals and the term dolphin is generally used for small cetaceans having a slender body & beak like snout, and porpoise for animal having a stocky body and blunt snout. Whales, Dolphin and Dugong constitutes one of the most important components of the aquatic ecosystem, mainly due to their gigantic size & the amount of food consumed by them.

2 Differences between Dolphin and Fish DOLPHIN Have hair whiskers on their face Dolphins give birth to live young (usually born tail first) and suckle their mother s milk The baby dolphin cannot live without its mother for at least a year Have lungs. Must come to the surface to breathe air through their blowhole Tail is horizontal and moves Warm-blooded FISH Do not have hair only scales covering their body Fish lay eggs or give birth to young that usually eat smaller plants and animals The baby fish are independent and do not need to be looked after Do not breathe air. Take oxygen from the water Tail is vertical and moves Cold-blooded Comparative chart of different marine mammals in the world and India Orders Number of species found globally Cetacea 10 families, 41 genera, & 78 spp. Sirenia 2 family, 3 genera, & 5 spp Number of species found in India 6 families, 20 genera & 26 spp. 1 family, 1 genera & 1 spp. HABITAT WISE CATEGORIZATION a.) The river dolphin. b.) Coastal and estuarine forms. c.) Marine species live in deep waters, which may be a resident of tropical water or live in cold waters, but migrate seasonally towards the tropics. eg. Blue Whale Among the 26 species found in India, 6 species belonging to 3 families of Order Cetacea are found in West Bengal. However the single species of Order Sirenia is not found in West Bengal. Species found in West Bengal 1). Platanista gangetica (Roxburgh,1801) Ganges River Dolphin 2). Neophocaena phocaenoides (Cuvier, 1829) Black finless Porpoise 3). Sousa chinensis (Osbeck, 1765)

3 Hump-Backed or Plumbeous Dolphin 4). Stenella attenuata (Gray, 1846) Pantropical Spotted Dolphin 5) Globicephala macrorhyncha (Gray, 1846) Short-Finned Pilot Whale 6) Orcaella brevirostris (Gray, 1866) Irrawaddy River Dolphin 1) Platanista gangetica (Roxburgh,1801) Ganges River Dolphin General appearance : Fusiform body, head prolonged into a long and compressed beak studded with teeth on each side, dorsal fin low and ridge-like, forehead rising steeply, prolonged into a long beak, distinct but short neck, dorsal low, ridge-like, located at midlength of the body and rudimentary, pectoral flippers are short and broad, more or less triangular in shape, tail fluke is horizontally placed and notched in middle, body is Slaty to sooty black throughout. Body weight 0.76 m long dolphin weighed 3.42 kg 1.99 m long weighed 84 kg Distribution : India, Nepal, Bhutan and Bangladesh 2) Neophocaena phocaenoides (Cuvier, 1829) Black finless Porpoise General appearance : Small sized porpoise with abruptly rising forehead, without beak, dorsal fin absent, abruptly rising forehead, without any distinct beak, neck small but distinct, no dorsal fin but low ridge, pectoral flippers small and elliptical, tail fluke compressed horizontally, about 55 cm wide, notched in middle, body colour dark slaty grey with purplish white patch on throat and lips. Body weight m long pregnant female weighed approx. 27 kg Distribution Coastal waters & estuaries from Persian Gulf, through Indian subcontinent (Pakistan, Srilanka, Bangladesh & Myanmar) to southeast Asia, north of China, Korea & Japan 3) Sousa chinensis (Osbeck, 1765) Hump-Backed or Plumbeous Dolphin General appearance : Adults usually have a long low hump on the back, with a small triangular dorsal fin on top, some forms lack hump

4 and have larger dorsal fin, head with long beak, demarcated from forehead by a notch, dorsal fin triangular in shape, but may be small or large or little elevated, pectoral flippers are broad at base, tail fluke horizontally flattened & notched in middle, body colour varies from bluish grey to white. Body weight 1.0 m long dolphin weighed 37 kg, 2.3 m long weighed 139 kg Distribution Coastal and inshore waters from South Africa, east through Indian subcontinent & Indonesia to southern China and queensland (Australia), Sri Lanka, Pakistan (Karachi coast) & tidal estuaries of Myanmar 4) Stenella attenuata (Gray, 1846) Pantropical Spotted Dolphin General appearance : Medium sized spotted dolphin with short and thick beak, a black stripe connects angle of gape with the flipper, a portion of rostrum and lower jaw white, head with short thick beak, well demarcated from forehead; portion of rostrum & lower jaw white up to the gape in adults, dorsal fin tall and black, located in the middle of back, pointed backwards, pectoral flippers falcate and black with black stripe present between angle of gape and flipper Tail fluke is notched in middle and black, body divided into dark upper & light (whitish or greyish) lower portion. Distribution Worldwide in tropical and subtropical waters of both coastal and offshore Includes Indian ocean and Javan Sea and Red Sea In Indian ocean, Sri Lanka, India (sunderbans), Maldive Islands, Gulf of Oman 5) Globicephala macrorhyncha (Gray, 1846) Short-Finned Pilot Whale General appearance : Body long and slender with bulbous forehead & protruding lips, teeth moderately large and confined to anterior half of rostrum, bulbous forehead, beak in form of protruding lips, notch present between and snout, dorsal fin is located at middle of the back, broad on base, half crescent in shape, pectoral flippers long, narrow and tapering, tail fluke horizontally flattened, 1.3 m in width, medially notched, body colour with black above with a white mark on throat and a pale patch behind dorsal fin Body weight : 4.2 m long whale weighed 680 kg Distribution

5 Found in warm temperate and tropical waters of the world including Indian Ocean from South Africa to Australia, Bay of Bengal, Maldive Island off the Sri Lankan coast, Savu Sea, seas around Java, Sumatra & Borneo 6) Orcaella brevirostris (Gray, 1866) Irrawaddy River Dolphin General appearance : Similar in size to Ganges river dolphin, with a bulzing forehead, no beak, downwardly pointed mouth, everted lips, dorsal fin blunt at tip and ellipsoid flippers, bulzing forehead with no beak, Body colour is bluish grey above and paler below with no distinct pattern, dorsal fin small, blunt at tip, situated at posterior half of back, pectoral flippers ellipsoid with oval tip, tail fluke horizontally flattened and notched in middle. Distribution Coastal waters from East coast of India through Myanmar, Thailand and Indonesia to northern Australia Food The dolphin and whales subsist mainly on crustaceans, cephalopods and fishes. Quantum of food taken depends upon their body size. (eg. A 26m long blue whale has been reported to consume 5 million krill's weighing about 2 ton.) The main reason for the population deterioration over the years is due to trade of products obtained from them. Trade is illegal, most of them go unnoticed and only a few of the trade are recorded. Commercial Exploitations Dolphins are killed for meat, fat and oil, bones for manures, ambergris (used as a fixture in perfumes), protein rich solid and liquid residue etc. Up to early 20th century, whales and dolphin are killed in a large number for extraction of oils from fats in Antarctic oceans resulting in dwindling of their population. However, the tendency to kill Dolphin has to a certain extent checked in recent years due to framing and promulgation of many national and international legislations Threats

6 The primary threat is the destruction of habitat and loss of available foods. The habitat of the dolphin is greatly affected by industrial and agricultural development. Due to pollution by sewage and chemical wastes and habitats mauled by cruising. Poisoning of the water supply from industrial and agricultural chemicals may have also contributed to population decline. From Uttaranchal to Hooghly in West Bengal, particularly in UP and Bihar, this blind aquatic mammal is seriously threatened. Many dolphins have suffered deep cuts from boat propellers, illness from ingestion of foreign objects and unnatural or poor quality food, and loss of natural foraging behavior. Entanglement in fishing nets can cause significant damage to local population numbers. The biggest threat the dolphins face is drowning in fishing nets. The mammals live in shallow waters near shore or in rivers and suffer high death rates as by catch in fishing nets. Pollution may be affecting the viability of the Dolphin species, especially considering the decline in flushing and dilution due to reduced flows. Massive fish kills have reportedly become common from industrial pollution in urban areas and from pesticides used on irrigated crops grown along the riverbanks. The pressures on river water supply and continued untreated discharge of pollutants result to a continuing decline in the amount and quality of dolphin habitat (Reeves and Chaudhry 1998). Deliberate killing for meat and oil was a traditional and widespread practice until at least the early 1970s (Pilleri and Zbinden ). Perhaps the most significant issue is the building of dams along many rivers, causing the segregation of populations and a narrowed gene pool in which dolphins can breed, that have severely fragmented the population and reduced the amount of available habitat (Smith and Reeves 200 Conservation Why conservation is necessary? Maintenance of essential ecological process and life support systems. Preservation of genetic diversity. Sustainable utilization of the genes, species and ecosystem. It is very important to protect and conserve dolphin populations, as once they are gone, they will be gone forever

7 How to achieve? To emphasize on the basic role of natural ecological process, bio-diversity and sustainable utilization at all levels of decision making. To identify conservation priorities with attainable goals. To promote establishment of protected area network, biosphere reserve, management and other conservation initiative for preservation the natural habitat. To promote conservation, consciousness within the public and community participation is to be developed To provide facilities for conservation education and community development programme. To establish efficient scientific information and decision support system for needs-driven research and conservation planning. Conservation measures Enforcement of regulations prohibiting marine mammals hunting by Indian Wildlife (Protection ) Act, 1972, Wildlife(Protection) amendment Act, Many National and International, Govt. and Non-Govt. Agencies ( NGO) like IUCN, WWF, WTI, UNDP etc., engaged for Dolphin conservation Many research projects are going on by Government and Non-government Agencies. Awareness programme Recommendations for survival To raise awareness about importance of conservation of marine mammals, local NGOs and school Level eco-clubs will be the most effective. Priority should be given to preserving all of its components including fishes that provide food for the marine mammal as well as the indigenous people. Local bodies are to be involved in management for conservation area. Fishing should be regulated to reduce the pressure on the feeding ground of marine mammals Fishing gear that harm marine mammals should be restricted in the primary habitats. To find out the migratory route of marine mammals by satellite imaging so that the fisherman can avoid that route to protect these animals

8 Regular monitoring is to be conducted To avoid stress on the food habitat of these animals, fishermen should be made aware to catch only the commercial species of fishes. Private and community managed fishing culture can be promoted in ditches, brakish water, making bheri in the coastal area and small ponds around the area To involve local resource managers and community groups for long term survival of these animals Guardianship is to be developed in and around the animal s habitat by involving community Based Anti-Poaching Units The prime location for dolphin and other aquatic mammals watching during low water seasons is to be selected for tourists by developing infrastructure Community managed tourism is to be promoted in the areas to improve the local economy Marine mammals usually feed upon smaller fishes and shrimps, the mesh size of fishing nets can be regulated for the selected only larger fishes and allow smaller fishes to escape It was observed that the use of gill net is destructive to the fishing population as it entangles fishes of all size that ultimately hampers breeding fish population. Both local and national media, print (news paper and magazines) and electronic (radio and TV), should extensively be made use of in highlighting the issues on the existing marine mammal population. It is seen that the local communities have religious and cultural belief regarding dolphin, sea cow and other marine mammals as a holy animal, conservation effort should be built on their existing belief rather than trying to impose a scientific basis for conservation at the very beginning References 1) Agrawal, V. C. and Alfred, J. R. B Handbook on Whales, Dolphins and Dugong from Indian Seas. Zoological Survey of India, Calcutta. 2) Venkataraman, K Natural Aquatic Ecosystems of India. Zoological Survey of India, Calcutta. 3) Agrawal, V. C., Das P. K., Chakraborty, S., Ghose, R. K., Mandal, A. K., Chakraborty, T. K., Poddar, A. K., Lal, J. P., Bhattacharya, T. P. and Ghosh, M. K State Fauna Series 3 : Fauna of West Bengal, Part 1: ) Basu, R. C., Khan, R. A. and Alfred, J. R. B Enviornmental

9 awareness and Wildlife conservation. Zoological Survey of India, Calcutta. 5) Alfred, J. R. B, Das, A. K. and Sanyal, A. K Faunal diversity in India. ENVIS Centre Zoological Survey of India, Calcutta. 6) Alfred, J. R. B, Ramakrishna and Pradhan, M.S Validation of Threatened Mammals of India. Zoological Survey of India, Calcutta.

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