A multi-disciplinary approach for investigating the ecology of dugongs in Con Dao Archipelago, Vietnam

A coastal view of the main island - Con Son on the way to Co Ong airport © Uy Nguyen  

Our project’s goal is to fill the current gaps on dugong ecology in Con Dao national park (NP) of Vietnam, with strong emphasize on aspects that driven conservation managements for this species at local level.

The dugong (Dugong dugon) is a conservation-dependent marine mammal inhabiting tropical and subtropical coastal waters. In Vietnam, dugong is extremely rare. Con Dao NP (east coast) and Phu Quoc island (west coast of Vietnam) are only two places where dugong sightings were confirmed. For Con Dao NP, which consist 120 square kilometer of sea area and 14 islands, previous study in 2002 recorded only 33 dugong sightings. Since 2002, no systematic survey has been done study this population. The presence of seagrass beds around Con Dao NP has been frequently used to argue that dugong foraging in this area. But until now, it is unclear whether the dugong feeding in Con Dao sea or they utilize the area for other purpose (e.g. mating, resting or socializing). This uncertainty resulted in under-investigation in protecting potential feeding grounds of dugong and other potentially important habitats for the species in Con Dao.

Fishing, most commonly long-line fishing and trawling, still takes place in Con Dao seagrass beds. Beside the disturbances cause by fishing activities to the seagrass meadows, abandoned fishing hooks, lines and nets pose a significant threat for the dugong. From July to August 2018, two dugongs were found dead in Con Dao NP. Necropsy showed concerning signs of interaction with fishery, such as rope marks on the fluke, or intestine preformation that potentially caused by shallowing left-over fishing hooks in seagrass beds. For a small population in Con Dao area, two mortalities within 02 weeks can cause a significant impact on the population survival.

This dugong was found stranded on Aug 3, 2018 in Con Dao area © Uy Nguyen 

With current gaps of information regarding the dugong ecology in Con Dao area, local conservation practitioners will continue to struggle in focusing their limited resources to protect this threatened population. Filling the current gaps on dugong ecology in Con Dao NP is crucial for dugong conservation in this area. To address this issue, we will use a multi-disciplinary approach to investigate the ecology of dugong in Con Dao Archipelago from October to August 2019. Two standardized methods we use to collect dugong ecology data are feeding trail monitoring and interview survey.

The main output of our project is the first comprehended baseline on the ecology of dugong in Con Dao archipelago. Our findings on how dugong utilizing the sea areas in Con Dao archipelago will evidence-based actions for Con Dao NP. Our findings on the spatial or temporal changes in dugong distribution in the area will also help implementing conservation actions effectively (e.g. in where and when Con Dao NP need to prioritize to implement their dugong protection activities).

Our specific objectives are: (1) assessing the spatiotemporal patterns of dugong’s presence in Con Dao NP; (2) investigating how the dugong utilize the sea area of Con Dao NP; and (3) identifying the hotspots for dugong conservation management in Con Dao NP.