Con Dao is an archipelago located about 100 km offshore of the southeast coast of Vietnam. The Con Dao area is one of only two locations in Vietnam – the other being the island of Phu Quoc in the eastern Gulf of Thailand, that have had relatively recent records of dugong sightings after the year 2000. The seagrass beds in Con Dao, which are mainly dominated by Halophila ovalis, Halophila minor, and Halodule uninervis, have been strictly protected from fishing and development by the National Park rangers. In combination with consistent dugong sightings reported by the park’s rangers, Con Dao National Park potentially contains important foraging habitat for this population of locally occurring and possibly resident dugongs.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
The dugongs that inhabit Con Dao National Park have been assessed as Vulnerable on a global scale in the IUCN Red List of Endangered species (Marsh and Sobtzick, 2015).
The dugong (Dugong dugon) is a coastal marine mammal inhabiting tropical and subtropical coastal waters (Marsh et al. 2011, Hines et al. 2012). Dugongs have been prioritized for conservation by three international conservation conventions including: The Convention on Biological Diversity (CBD); the Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES); and the Convention on Migratory Species of Wild Animals (CMS) (Marsh and Sobtzick, 2015). Dugongs are also mentioned in the Coral Triangle Initiative as species whose habitats need to be protected (Marsh and Sobtzick, 2015). All conventions mention the lack of robust ecological data for dugong conservation.
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
Since 2002, no systematic research has been conducted on the dugong in the Con Dao archipelago, which results in enormous gaps of information on the abundance and distribution of dugongs as well as anthropogenic threats. Cox (2002), reported observing a total of 33 individuals, including several calves between 2000-2002. Cox believed there were about 10 dugongs in the Con Dao area but this estimate was mainly based on his observations in one location, not a formal survey of the whole archipelago (Cox, 2002). The World Wildlife Fund (WWF) also conducted an interview survey in Con Dao and Phu Quoc islands but only to document inadequate information on the dugong (Adulyanukosol, 2002). From 2010 until October 2018, several opportunistic sightings of dugong were made by the marine patrolling team of the Con Dao NP. In addition the Park is located approximately 100 km offshore of the southeast coast of Vietnam, and as such it is inferred that the individuals in the locally occurring population are isolated to surrounding dugongs on the mainland and beyond. Remarkably, from July to August 2018, two dugongs were found dead at the same time in the Park. Necropsies performed by trained veterinarian of Con Dao National Park showed signs of interactions with fishing gear, such as rope marks on the flukes, and intestine perforations potentially caused by shallow remnant fishing hooks in a seagrass bed. For such a small population, two mortalities within two weeks could be a significant threat to what we assume is a small group of animals (Marsh and Sobtzick, 2015).
Criterion C: Key Life Cycle Activities
Sub-criterion C2: Feeding Areas
Without a systematic survey, there has been limited information on the distribution patterns of dugong in this area. The seagrass beds in Con Dao, which are mainly dominated by Halophila ovalis, Halophila minor, and Halodule uninervis, have been strictly protected from fishing and development by the National Park ranger, and their presence and the number of dugong sightings around Con Dao National Park has been frequently used to argue that dugongs are foraging in the Park (Pham, 2003). This was backed up by the historical occurrence and consistency of dugong sightings. We suggest, based on the consistency of sightings over time, that the seagrass meadows in this area are important feeding grounds for the dugong, especially as the Park is isolated from the mainland. Additionally, the necropsy of two freshly stranded dugongs found in Con Dao in August 2018 revealed a stomach full of seagrass, implying that these dugongs could have foraged in nearby seagrass.
Adulyanukosol, K. 2002. Report of Dugong and seagrass survey in Vietnam and Cambodia. Kanjana Adulyanukosol, Phuket Marine Biological Centre, Phuket 83000 Thailand. 4 pp.
Cox, N. 2002. Observations of the Dugong Dugong dugon in Con Dao National Park, Vietnam, and recommendations for further research. Unentitled Report. 8 pp.
Cox, N., Tran, C.K., Hines, E. 2003. Proceedings of the Workshop on the Conservation of the Dugong and Seagrass Habitats in Vietnam January 20-2- 2003. World Wildlife Fund (WWF), Indochina Programme, Hanoi, Vietnam.
Con Dao National Park website. 2013. Made Available from < http://www.condaopark.com.vn/vn/tai-nguyen-sinh-vat-bien-con dao.html>
Con Dao National Park. 2014. Annual report on monitoring valuable marine animal. Internal report (in Vietnamese). Made Available from < http://www.condaopark.com.vn/vn/tai-nguyen-sinh-vat-bien-con dao.html>
Con Dao National Park. 2015. Annual report on monitoring valuable marine animal. Internal report (in Vietnamese). Made Available from < http://www.condaopark.com.vn/vn/tai-nguyen-sinh-vat-bien-con dao.html>
Con Dao National Park. 2016. Annual report on monitoring valuable marine animal. Internal report (in Vietnamese). Made Available from < http://www.condaopark.com.vn/vn/tai-nguyen-sinh-vat-bien-con dao.html>
Con Dao National Park. 2017. Annual report on monitoring valuable marine animal. Internal report (in Vietnamese). Made Available from < http://www.condaopark.com.vn/vn/tai-nguyen-sinh-vat-bien-con dao.html>
Lang Van Ken. 1997. New Record of dugong in Con Dao waters, southern Vietnam. Sirenews 27: 17-18.
Hines, E.M., Reynolds, J.E., Aragones, L. V. and Mignucci-Giannoni, A.M.M. 2012. Sirenia conservation: Issues and strategies in Developing countries. Florida, US. University Press of Florida.
Pham, H.D. 2003. The primary assessment on the dugong population in Viet Nam. Pages 64–71 Proceedings on the 4th SEASTAR 2000 Workshop. Kyoto University, Kyoto.
Isaac, N.J.B., Turvey, S.T., Collen, B., Waterman, C. and Baillie, J.E.M. 2007. Mammals on the EDGE: Conservation priorities based on threat and phylogeny. PLoS ONE 2.
Marsh, H. and Sobtzick, S. 2015. Dugong dugon. The IUCN Red List of Threatened Species 2015: e. T6909A43792211. 8235 < http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T6909A43792211.en>
Nguyen, V.V. 2018. Con Dao National park. Personal Communication. Van Bree, P. J., and Gallagher, M. D. 1977 Catalogue de la collection des mammiferes marin du Museum de Bordeaux. Ann. Soc. Sci. Nat. Char-marit 6: 289-307.
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