Con Dao IMMA

Criterion A – Species or Population Vulnerability

The dugong has 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, Hines et al. 2008). From 2010 until October 2018, several opportunistic sightings of dugong were made by the marine patrolling team of the Con Dao National Park. In addition the Park is located approximately 100 km offshore of the southeast coast of Vietnam, and it is inferred that the individuals in the locally occurring population are an isolated group. In July to August 2018, two dugongs were found dead 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 is limited information on the abundance and distribution patterns of dugongs 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.