Conservation
status of the globally Vulnerable Dugong Dugong
dugon (Müller, 1776) (Sirenia: Dugongidae) in the coastal waters of
Kalpitiya area in Sri Lanka
D.M.S.S. Karunarathna 1,
M.A.J.S. Navaratne 2, W.P.N. Perera 2 & V.A.P.
Samarawickrama 3
1 Nature Exploration & Education Team, No. B-1 / G-6, De Soysapura, Morauwa
10400, Sri Lanka
2 IUCN – Sri Lanka country
office, No. 53, Horton Place, Colombo 7, Sri Lanka
3 No. 104,
Bulawaththa, Gannoruwa, Peradeniya, Sri Lanka
Email: 1 dmsameera@gmail.com
(corresponding author),3 woodowl@gmail.com
Date
of publication (online): 26 January 2011
Date
of publication (print): 26 January 2011
ISSN
0974-7907 (online) | 0974-7893 (print)
Editor: Kumaran Sathasivam
Manuscript
details:
Ms # o2235
Received 11
June 2009
Final received
22 November 2010
Finally
accepted 06 December 2010
Citation: Karunarathna, D.M.S.S., M.A.J.S. Navaratne,
W.P.N. Perera & V.A.P. Samarawickrama (2011). Conservation
status of the globally Vulnerable Dugong Dugong dugon (Müller, 1776) (Sirenia: Dugongidae) in the
coastal waters of Kalpitiya area in Sri Lanka. Journal of Threatened Taxa 3(1): 1485-1489.
Copyright: © D.M.S.S. Karunarathna, M.A.J.S. Navaratne, W.P.N. Perera
& V.A.P. Samarawickrama 2011. Creative Commons
Attribution 3.0 Unported License. JoTT allows unrestricted use of this
article in any medium for non-profit purposes, reproduction and distribution by
providing adequate credit to the authors and the source of publication.
Acknowledgements:The authors wish to thank Dr.
Channa Bambaradeniya for critically reviewing this manuscript. We also would like to thank Mrs.
Suseema Liyana-Arachchi (GN), Mrs. Inoka Amaradeva (GN), and villagers in
Soththupitiya, Thirikkapallama, Karative, Puttalama, Mampuriya, Kandakuliya,
Gangewadiya, Theheliya, Palliyawasalture, Kuringyampitiya, Kalpitiya,
Uchchamunei, Bathtalangunnduwa, Pubudugama and Sevvanthive villages for their
cooperation and sharing their observations, and also IUCN Sri Lanka country office
for facilitating the conduct of this study. Finally, we wish to thank Mr. Niranjan Karunarathna (YZA)
for numerous help during the preparation of this paper.
The
Dugong Dugong
dugon is the
only extant species belonging to the family Dugongidae, order Sirenia (Phillips
1984; Weerakoon & Goonatilake 2006; Ilangakoon 2006; Ilangakoon & Tun
2007). It is distributed in
coastal and marine environments ranging from northwest to northeast Australia,
southeast to northeast Africa and the south and southeastAsia region (Smith & Marsh 1990; Adulyanukosol 2000; Marsh et al. 2002; D’
Souza & Patankar 2009). It is
listed as a globally Vulnerable species (Marsh 2008) and also listed in CITES
appendix I. The Dugong is one of a
suite of large, long-lived marine vertebrates, including turtles and inshore
cetaceans, which are under pressure from human activities (Phillips 1984; Preen
1998), and its maximum longevity observed is 73 years (Marsh et al. 1984). The gestation period is estimated to be
about 12-14 months, with females birthing single young (Marsh 1986). The Dugong is a grazer
which feeds on sea-grasses in near shore areas (Marsh et al. 2002;
Chansue et al. 2006).
Dugongs
look rather like a rotund dolphin without a dorsal fin. The head is distinctive with the mouth
opening ventrally below a broad flat muzzle (Phillips 1984) covered sparsely
with short stout hairs that are most developed around the mouth (Marsh
1989). The Dugong has been given
the highest level of legal protection in South Asia, being listed under
Schedule (I) of the Indian Wildlife Protection Act (Marsh et al. 2002; D’ Souza
& Patankar 2009), and also in the Wildlife and Nature Protection Ordinance
in Sri Lanka “Act No. 1. of 1970” (Phillips
1984). The species is a relatively
large and rare marine mammal in Sri Lanka (Santiapillai 1981; Phillips 1984;
Ilangakoon 2006). The occurrence
of the Dugong in Sri Lanka’s waters appears in the literature in the late 19thcentury, at which time it seems to have been rare (Haley 1884; Nevill
1885). This article intends to
document the conservation status of the Dugong in the coastal waters of the
Kalpitiya and Puttalama areas in northwestern Sri Lanka, based on recent field
observations and information gathered from local communities (Image 1).
The habitat of Dugong in Kalpitiya and Putalama areas: The Kalpitiya and Puttalama Lagoon area
has several plant species: Aegiceras
corniculatum, Avicenia marina, Acrostichum aureum, Acanthus
illicifolius, Bruguieria cylindrical, B. gymnorhiza, Ceriops
tagal, Exoecariya agallocha, Hibiscus tiliaceus,Rhizophora mucronata,R. apiculata, Scyphiphora hydrophyllaceae, Sonneratia alba and Xylocarpus
granatum dominant
mangrove forests. The lagoon also harbours patches of sea-grass beds, which
consists of species such as Halophila
beccarii, H. decipiens, H. ovalis, H.
ovata, Thalassia hemprichii, Cymodocea rotunda, C.
serrulata, Halodule uninervis, H. dinifolia, and Syringodium
isoetifolium as
dominant aquatic vegetation. The
Dugong - preferred sea grass, Haloduleand Halophila, are also present in Puttalama Lagoon
(Marsh et al. 2002; pers.obs.).
The
Dugong visits the sea grass beds in the near-shore areas of Kalpitiya, while
fishermen have also observed this species in the Kalpitiya Lagoon area. The average depth of the near-shore
area is about 2m, while the Kalpitiya Lagoon area is approximately 1.5m in
depth. The sea area and brackish
water temperature varies from 27-28 0C. The average annual rainfall in this area is 1,100mm, with
most of the rainfall occurring from December to March, with occasional rains in
the other months. The weather
gradually becomes very dry from August to December with the highest
temperatures recorded in August. The mean annual temperature in the Puttalama District is 280C
with a maximum of 320C and a minimum of 240C.
Recent field observations: We interviewed 78 fishermen (32
fisheries societies in 21 fisheries villages) engaged in near-shore fishing
activities in the Kalpitiya and Puttalama areas. Their frequency of Dugong observations averaged once in
every 100 fishing trips, indicating a low chance of encountering Dugongs in
this area. Two specimens were
observed in fisheries bycatch during the study period; on 05 December 2007
(Image 2) in the Soththupitiya Village (8007’03.41’’N& 79044’21.44’’E) in Kalpitiya Peninsula, and on 21 October 2008
in Puttalama. The Soththupitiya
specimen was an adult male with a snout to tail end length of approximately
1.5m that was accidentally caught in a fishing net in the Kalpitiya Lagoon
area. The body
was taken away by junior officers of Kalpitiya navy camp. Some fishermen had observed Dugongs in
Puttalama Lagoon in Uchchamunei and Kalpitiya. They did not provide the exact dates of these
observations. There is an accepted
fact that the Muslim community in the area does not like to catch and eat
Dugongs for religious reasons, which is useful information for education and awareness
programmes.
Trends in population status: According to Santiapillai (1981), prior
to the mid 1980s, Dugongs were both abundant and widely distributed along the
northwestern coast of Sri Lanka, although no numbers are available regarding
the abundance. At this time they
were actively hunted in the Puttalama area using gillnets. Over the past 30 years however, Dugong
numbers have declined dramatically and sightings are now very rare. Interviews
fishermen yielded just 12 reported sightings since the beginning of year 2000
(9 incidental captures and 3 live animals), which is a small number even for
the 1% observation frequency mentioned above. According to fishermens in this area, a small resident
population is known to exist in just two remaining areas, Kalpitiya (Images 3
a, b, c) and Uchchamunei area. In
some areas Dugongs are referred to as ‘Caddadt pandri’ (sea pigs) in Tamil
(Phillips 1984). An island near
Kalpitiya is called ‘Pandipitiya’ (pig island) most probably refering to Dugong
island.
Threats to Dugong in Kalpitiya and Putalama areas: The main threat to Dugongs in the past
was deliberate hunting for meat (Ilangakoon 2006). Anthropogenic threats to Dugong in the Kalpitiya area can be
divided into direct and indirect impacts. According to information gathered from local communities, Dugongs were
killed there at the rate of one animal every four months. Direct impacts include hunting, habitat
loss, habitat degradation, water pollution and accidental entanglement as a
result of commercial fishing practices. Indirect impacts include agricultural practices such as land clearing
and the application of fertilizers with subsequent run-off impacting sea grass
beds, which serve as the feeding habitats of the Dugong. Other indirect impacts include
disturbance and alteration of habitat from mining, use of harmful fishing
practices such as drag nets / push nets, dredging and trawling activities. The sea grass beds are also adversely
affected by sedimentation related to aquaculture ponds in the area. However, according to the historical
notes from 1957 and 1959, some 100 to 150 dugongs were taken each year in the
Mannar District of Sri Lanka (Phillips 1984).
Recommendations for conservation of Dugong: The following suggestions are made to
conserve the dwindling populations of Dugong in the northwestern coastal waters
of Sri Lanka:
(i)
Scientific research and monitoring: A systematic research on this threatened
marine mammal should be initiated, to document its current distribution in the
area, habitat status, breeding and migration
patterns. The local fishermen
should be involved in a community based monitoring programme to document
observations related to Dugong, including records on bycatch. Priority attention should be placed to
document the small resident population of Dugong in this area, as informed by
the fishermen. The National
Aquatic Resources Research and Development Agency (NARA) Station in Kalpitiya
could play a lead role in monitoring programs, also Department of Wildlife
Conservation (DWC).
(ii)
Environmental education and awareness: A well-planned and targeted program has
to be carried out among local communities on the need to conserve the Dugong,
and other marine mammals, reptiles (i.e., turtles, sea snakes) and coral reef
fish in the area. Such a good
programme should be targeted at discouraging local communities from consuming
Dugong meat. The Central
Environmental Authority (CEA), Ministry of Education, Educational Publication
Department, and environmental related NGO’s may perhaps play the most important
role in environmental education and awareness programmes, also the Department
of Wildlife Conservation (DWC).
(iii)
Declaration of a protected area: There is tremendous
potential to declare a marine and coastal Ramsar site (an internationally
important wetland) in this area, which would enable to conserve the habitats of
not only the Dugong, but several other marine animals inhabiting this
region. The naval base in
Kalpitiya could play a vital role in the conservation of Dugongs in this
area. We believe that the lagoon
areas are very important but they need to be planned and managed in such a way
that they balance the needs to protect the marine environment whilst promoting
poverty alleviation, integrated livelihoods and a human rights approach to
development along the Puttalama Lagoon.
References
Adulyanukosol,
K. (2000). Dugong survey in Thailand. Biologia
Marina Mediterranea7(2): 191-194.
Chansue,
N., S. Monanunsap & A. Sailasuta (2006). Pyometra with diffuse fibrin fibrinopurulent peritonitis in a
Dugong (Dugong
dugon). Proceedings of AZWMP, Chulalongkorn
University Faculty of Veterinary Science, Bangkok, Thailand, 56pp.
D’ Souza, E. & V. Patankar
(2009). First
underwater sighing and preliminary behavioural observation of Dugongs (Dugong dugon) in the wild from Indian waters,
Andaman Island. Journal
of Threatened Taxa1(1): 49-53.
Ilangakoon, A.D. (2006). Taxonomy and current
satus Marine mammals in Sri Lanka, pp. 302-308. In: Bambaradeniya, C.N.B. (Ed.). Fauna of Sri Lanka: Status of
Taxonomy, Research and Conservation,
IUCN Sri Lanka, Colombo, xiii+308.
Ilangakoon, A.D. & T. Tun (2007). Rediscovering the Dugong (Dugong dugon) in Myanmar and capacity building for
research and Conservation. Raffles
Bulletin of Zoology55(1): 195-199.
Haley,
A. (1884). Administration Report of the Director of the Colombo museum for
1883. National Museum of Sri Lanka, Colombo, 18pp.
Marsh,
H. (1986). The status of the dugong in Torres Strait, pp. 53-76. In:
Haines, A.K., G.C. Williams & D. Coates (eds.). Torres Strait Fisheries Seminar,
Port Moresby,Australian Government Publishing Service: Canberra, 285pp.
Marsh,
H. (1989). Chapter
57 – Dugongidae, pp. 1-18. In: Walton, D.W. & B.J. Richardson (eds.).Fauna of
Australia: Volume 1B Mammalia.CSIRO Publishing / Australian Biological Resources Study
(ABRS), 827pp.
Marsh, H. (2008). Dugong dugon. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>. Downloaded on 14 January 2011.
Marsh,
H., G.E. Heinsohn & P.W. Channells (1984). Changes in the
ovaries and uterus of the dugong, Dugong
dugon (Sirenia, Dugongidae) with age and reproductive activity. Australian
Journal of Zoology 32:
743-766.
Marsh,
H., H. Penrose, C. Eros & J. Hugues (2002). Dugong, Status Reports and Action
Plans for Countries and Territories. Early Warning and
Assessment Report Series of United Nation Environmental Programme (UNEP),
162pp.
Nevill,
H. (1885). Dugong. Taprobanian 1(1): 2.
Phillips,
W.W.A. (1984). Manual
of the Mammals of Sri Lanka, 2nd Revised Edition, Part – 3. Wildlife and Nature
Protection Society of Sri Lanka (WNPS) Colombo, pp. i-xxxv+269-389, xx-xxxix
plts.
Preen,
A. (1998). Marine
protected areas and Dugong conservation along Australia’s Indian Ocean Coast. Environmental Management 22(2): 173-181.
Santiapillai,
C. (1981). On the
ecology and conservation of the dugong Dugong
dugon in Sri
Lanka. Tiger
Paper 8(1):
2-6.
Smith, A. & H. Marsh (1990). Management of
Traditional hunting of Dugongs [Dugong
dugon (Müller, 1776)] in the northern great Barrier reef, Australia. Environmental
management 14(1):
47-55.
Weerakoon, D.K. & W.L.D.P.T.S.
de A. Goonatilake (2006). Taxonomic status of the Mammals of Sri Lanka, pp. 216-231.In: Bambaradeniya, C.N.B. (ed.). Fauna
of Sri Lanka: Status of Taxonomy, Research and Conservation, IUCN Sri Lanka, Colombo, xiii+308pp.