IRRAWADDY DOLPHINS Presentation byDr Madhusudan Subudhi

IRRAWADDY DOLPHIN IN CHILIKA LAKE

Taxonomy

Kingdom _ Animalia Phylum _ Chordata Class _ Mammalia Order _ Cetacea Family _ Platanistidae Genus _ Orcaella Species _ Orcaella

Brevirostris

Physical description

Colour Slaty blue to slaty grey Under parts are slightly palerLength 180 to275 cmsBody weight May go up to 190 kg(418 lbs)

Gross Anatomy

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 Irrawadi dolphine desected by Dr M.subudhi & Mr Mumtajalli khan.

Grossly healthy kidneys of a dead Irrawady dolphin dissected by Dr M.Subudhi & Mr.Mumtaz alli 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

Panoramic view of Irrawaddy river

Panoramic view of Irrawaddy river

World wide habitats & population

1.BANGLADESH 5832 (Bay of Bengal)

2.BANGLADESH 451 (brackish Sundarban mangrove forest)

3.INDIA 138 (brackish water Chilika lake)

4.LAOS/CAMBODIA 114-152 (Mekong river)

5.INDONESIA N.A (fresh water Mahakam river)

6.PHILLIPINES 77 (brackish water,inner Malampaya sound)

7.MYANMAR 58-72 (370 km stretch of Irrawaddy river)

8.THAILAND <50 (in the brackish Sangkhala lake)

Panoramic view of Irrawaddy river

Bangladesh as fresh,brackish & salt water habitat Sundarban delta

Mangrove forest

Chilika lake as brackish water habitatChilika 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

ExtinctEx- ExtinctEw- Extinct in the wildEndangeredCr- Critically endangeredEn- EndangeredVu- VulnerableLower listNT- Near threatenedLC- Least concernedCd- 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)

Decomposed dolphin

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.