Gross anatomy Bulging fore head A very short beak Pectoral fin is broadly triangular Small dorsal fin towards posterior end of the back U shaped blowhole opens to the front(unlike other sps) 12 to 19 teeth on each side of each jaw. Narrow pointed peg like teeth about 1cm length
Gross Anatomy (contd) Two unique anatomical features of this sps: Stomach is divided into two into two compartments Muscular part & glandular part Cardiac sphincter is absent
Male reproductive organ of dead Irrawadidolphinedesected by Dr M.subudhi & MrMumtajalli khan.
Grossly healthy kidneys of a dead Irrawady dolphin dissected by Dr M.Subudhi & Mr.Mumtazalli Khan
Physical behavior They prefer coastal, brackish & fresh water of tropical & subtropical Indo pacific. Feeds on fishes ,crustaceans, cephalopods & fish eggs. Breathes at 70 to 150 seconds intervals. Usually dives for an average of 30 to60 seconds but larger dives up to 12 minutes have been recorded. Swim rate recorded up to 25 kms/hour.
Physical behavior(contd) Irrawadi dolphins are less active than other dolphins Only the uppermost part of dorsal fin becomes visible during a slow rolling dive They never bow ride
Breeding behavior Sexually mature around 4to 6 years age Gestation period is 14 months In Semeyang lake/Mahakam river(Malaya) mating season recorded to be April toJune But in Jakarta calves borne between July to december New borne measures 96cm,body weight 12.3kg.Body weight at weaning aapx.45kg. Though calves consume fish at 6months age but nursed up to 2 years
Origin Ayeyarwady river or Irrawaddy river which flows from north to south in Myanmar. Name derived from the Sanskrit word Iravati(minor Goddess in Indian mythology) or from her son Airabat the elephant Irrawaddy is the largest river of Burma about 2170 km long
Bangladesh as fresh,brackish & salt water habitat Sundarban delta Mangrove forest
Chilika lake as brackish water habitat Chilika near sea mouth Nalaban
Panoramic view of inner Malampaya sound (Philipines)Brackish water habitat
Brackish water habitat of Sangkhala lake(Thailand)
Categorization of IUCN red list Extinct Ex- Extinct Ew- Extinct in the wild Endangered Cr- Critically endangered En- Endangered Vu- Vulnerable Lower list NT- Near threatened LC- Least concerned Cd- Conservation dependant
Analysis of threat as per IUCN red list Irrawaddy dolphin is classified as VULNERABLE on the IUCN red list and listed in appendix-1 of CITES (Conservation of International trade in endangered species) In Mahakam river & Malampaya sound classified as critically endangered
Threats Irrawaddy dolphins are more susceptible to human conflicts than most other dolphins who live farther in the ocean. Drowning in gillnets is the main threat throughout their range. Majority of reported deaths in all subpopulations is due to accidental capture and drowning in gill nets, dragnets, bottomset crab nets(in philipines).
Gillnetting the No 1 threat forIrrawaddy dolphin
Threat:Chilika experience Author has conducted post murtem of 10 dead dolphins between2005 to 2008. 4 were putrified enough to opine any cause of death. 5 deaths are due to traping followed by drowning in gill nets bearing injuries on tongue,base of the tail and skin exfoliations. 1 death is due to lungs desease (focal necrosis of lungs)
Lungs of dead Irrawaddy dolphin with focal necrotic lesions
Researchers working on threat analysis & conservation strategies
Threat:Chilika experience Unregulated fishing Introduction newer varieties of fishing nets which are almost invisible under water. Motorized propeller boats, large in number Tourist boats approach much closer to dolphins, even sometimes chase them. Pollution of water, change in salinity, change in water temperature and siltation are less emphasized.
Ongoing conservation initiativesChilika experience Mapping dolphin population, distribution and movement by using GPS. Imposition of fines on gill and seine netting in Satpada region.(Orissa marine fisheries regulation act) Fines on tourist boats found chasing dolphins Ongoing training in dolphin watching guide- lines by CDA funded by WDCS. Distribution of booklets and pamphlets on sustainable fisheries
Action plan Establishing core conservation areas where gillnets and motorized boats are to be banned. Promoting net attendance rules and providing training on safe release of entangled dolphins. Providing alternative or diversified employment to gillnet fishermen. Research & development with acoustical deterr-ants and reflective nets.