|Scientific Name:||Dugong dugon (Müller, 1776)|
|Red List Category & Criteria:||Vulnerable A2bcd+4bcd ver 3.1|
|Assessor(s):||Marsh, H. & Sobtzick, S.|
|Reviewer(s):||Hodgson, A., Pilcher, N.J. & Kwan, D.|
Marsh et al. (2011) made a crude estimate of the Dugong’s extent of occurrence (EOO) as 860,000 km2 based on potential habitat (waters <10 m deep in its known range). This spans approximately 128,000 km of coastline across at least 37, and up to 44, countries and territories. Although the Dugong still occurs at the extremes of its range, Husar (1978) and IUCN (2009) list the Dugong as extinct in the waters of several islands including: the Maldives, the Lakshadweep Islands, Mascarene Islands of Mauritius and Rodrigues, and Taiwan (Husar 1978). Although this species may only have been vagrant at some of these islands (e.g. Taiwan, Hirasaka 1932), there is historical evidence of substantial Dugong populations off Mauritius and Rodrigues Islands; these populations were harvested in the 18th century (Cheke 1987). Cheke quotes historical accounts of a dugong fishery on Rodrigues in the 1730s. There is also anecdotal evidence that the area of occupancy (AOO) of the Dugong has declined in many parts of its range, especially along the coasts of east Africa and India.
The only reference site is the urban coast of Queensland between Cooktown and Brisbane, Australia where a 40 year time series of catch rates in nets set for bather protection indicates that the Catch Per Unit Effort (CPUE) in 1999 was only 3% of that in 1962 (Marsh et al. 2005). This CPUE is considered an index of Dugong decline in the region from all causes during this period. This decline and modern aerial survey estimates of Dugong abundance were used to backcast the population in the region in the early 1960s (which would be expected to have been lower than that at the time of European settlement as a cottage commercial industry for Dugong oil had existed at several locations along this coast since the 1850s). The extrapolation suggested that the region supported 72,000 (95% CI 31,000, 165,000) Dugongs in the early 1960s compared with an estimated 4,220 (95% CI 2,360, 8,360) Dugongs in the mid 1990s. The seagrass habitat in the region is currently insufficient to support 72,000 Dugongs, a result which suggests that the habitat had also declined or that the shark net CPUE has overestimated the decline (see Marsh et al. 2005). If the magnitude of this decline was robust and typical of the entire range of the Dugong, the Dugong would qualify for being classified as Critically Endangered at a global scale. However, there are sites in Australia that support large populations of Dugongs (e.g. Shark Bay, Torres Strait) where it is unlikely that such a decline has occurred (Marsh et al. 2011, unpublished).
The major causes of the Dugong’s decline along the urban coast of Queensland are still present in most of the Dugong’s range as follows: gill netting, subsistence hunting, habitat loss from extreme weather events that are likely to be exacerbated by climate change, human settlement and agricultural pollution. The magnitude of these threats is likely to be greater in most other parts of the Dugong’s range than in Queensland. The Queensland coast supports a low human population density relative to most other parts of the Dugong’s range and has a well- developed system of marine parks and pro-active management. Nonetheless there is evidence of ongoing decline in Dugong numbers (Sobtzick et al. 2012) along the urban coast of the Great Barrier Reef Region largely attributed to habitat loss associated with extreme weather events.
Marsh et al. (2011) undertook a regional assessment of the Dugong and concluded that the East African population was likely ‘Endangered’; Red Sea and Gulf of Aden ‘Data Deficient’; Arabians Gulf ‘Data Deficient’; Indian sub-continent and Andaman and Nicobar Islands ‘Endangered’; continental South East Asia ‘Endangered’; archipelagic East and South East Asia ‘Data Deficient’; Western Pacific Islands ‘Data Deficient’; and Palau and the Japan (Ryukyus) as Critically Endangered. The most recent assessment of the Australian population (Woinarski et al. 2014) concluded it was ‘Near Threatened’. The Dugong’s confirmed range states include a mix of developing and developed countries and territories including countries and territories with a very high Human Development Index (HDI), countries with a high HDI, countries with a medium HDI and three countries with a low HDI (Marsh et al. 2011). The outlook for Dugongs in countries with a very small Dugong population and/or a low HDI must be poor. These countries include Brunei, Cambodia, China, Comoros, Djibouti, Egypt, Iran, Japan, Kenya, Madagascar, Mayotte, Mozambique, Myanmar, Papua New Guinea, Singapore, Sri Lanka, Sudan, Tanzania, Viet Nam and Yemen. Nonetheless, four countries/territories with a very high HDI (Australia, New Caledonia, Qatar and the United Arab Emirates) support substantial populations of Dugongs (hundreds or thousands; Marsh et al. 2011), although even among and within these countries/territories the prospects are uneven. Because of the uncertainty associated with the assessment of the status of the Dugong, we suggest that the classification should remain as Vulnerable.
|Previously published Red List assessments:|
|Range Description:||Dugongs inhabit coastal and island waters between East Africa and Vanuatu between latitudes of about 27° north and south of Equator. Spanning approximately 128,000 km of coastline (860,000 km2) across at least 37 and and possibly occur in an additional seven states and territories (Marsh et al. 2011, N. Pilcher pers. comm).|
Native:Australia; Bahrain; Brunei Darussalam; Cambodia; China; Cocos (Keeling) Islands; Comoros; Djibouti; Egypt; Eritrea; India (Andaman Is., Laccadive Is., Nicobar Is.); Indonesia; Japan (Nansei-shoto); Jordan; Kenya; Madagascar; Malaysia; Mayotte; Mozambique; New Caledonia; Palau; Papua New Guinea (Bismarck Archipelago); Philippines; Qatar; Saudi Arabia; Seychelles; Singapore; Solomon Islands; Somalia; Sri Lanka; Sudan; Tanzania, United Republic of; Thailand; Timor-Leste; United Arab Emirates; Vanuatu; Viet Nam; Yemen (Socotra)
Regionally extinct:Mauritius (Rodrigues - Native); Taiwan, Province of China
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Five countries/territories (Australia, Bahrain, Papua New Guinea, Qatar and the United Arabian Emirates) support substantial subpopulations of Dugongs (thousands) with tens of thousands of Dugongs in northern Australia/Papua New Guinea alone (Marsh et al. 2011, unpublished). The percentage of mature individuals is likely to vary between various subpopulations, but is likely to be somewhere between 45% and 70% (Marsh et al. 2011). Genetic information on Dugong stocks is mostly limited to the Australian region. Recent work based on mitochondrial DNA (Blair et al. 2014) shows that the Australian Dugong population is not panmictic. The Australian population still has high genetic diversity, indicating that recent population declines are not yet reflected in the genetic makeup of the population. Seddon et al. (2014) used microsatellite markers to demonstrate low, but significant, population differentiation within a regional in southern Queensland. Further data (D. Blair unpublished data) using the same genetic markers indicate considerable differentiation between southern and northern Queensland populations. Preliminary population-genetic and phylogeographic studies on Dugongs outside Australia are ongoing. These studies suggest strong regional differentiation. Australian populations are largely distinct from those elsewhere; populations in the Western Indian Ocean (Red Sea, Persian/Arabian Gulf, East Africa) are rather uniform and with limited genetic diversity; Madagascar might harbour a distinct lineage. The situation for the Indo-Malay Region is unclear but possibly more than one historical lineage occurs there. Thailand (Palmer 2004, L. Parr unpublished data) and Australia (McDonald 2005, Blair et al. 2014) are home to distinct matrilines that possibly diverged during Pleistocene sea-level fluctuations, but are now able to mix geographically within those regions|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Habitat requirements for Dugongs include coastal areas, shallow to medium deep, warm waters (15-17°C minimum with behavioural thermoregulation), seagrass beds supporting sub-tropical and tropical species of seagrass, particularly low fiber species (Hines et al. 2012, Marsh et al. 2011). Dugongs show great variability in movement patterns and migration, depending on the study area and the influence of seasonal temperature or rainfall on regional ecosystems. Long-distance movements by Dugongs along the Queensland coast are well-documented (Sheppard et al. 2006), even though Dugongs do not appear to undertake regular migrations and individual movements are individualistic (Sheppard et al. 2006, Marsh et al. 2011, Gredzens et al. 2014). Cope et al. (2015) used pedigree analysis based on individual genetic markers to infer the movements of Dugongs between locations in southeast Queensland including Moreton Bay and Hervey Bay. They found that approximately 30% of assigned parents had at least one offspring found in a different locality, implying recent movement of the parent or offspring. This analysis suggested markedly more movement between localities than detected through repeated direct sampling of individuals (Seddon et al. 2014) or through telemetry (Sheppard et al. 2006).|
|Generation Length (years):||22-25|
|Use and Trade:||Archaeological evidence confirms exploitation of Dugongs by early humans. As long as 6,000 years ago, Dugongs on the small island of Akab in the United Arabian Emirates were hunted for food (Méry et al. 2009). Excavations in the Torres Strait, Australia, has revealed that Dugong hunting in this region dates back at least 4,000 years and possibly up to 7,000 years (Crouch et al. 2007, Wright 2010) and that the harvest has been substantial for at least 400–500 years (McNiven and Bedingfield 2008). Although hunting is now legally banned in most countries, there are important exceptions for the subsistence use by traditional peoples. In Australia, the Dugong hunting rights of ‘Native Title Holders’ (indigenous people who can prove continuous connections to their traditional land and sea country) have been consistently upheld by the courts in a series of landmark decisions since 1993. Dugong hunting still has considerable cultural significance to coastal Aboriginal and Torres Strait Islander peoples across northern Australia, and Dugong meat is considered by these groups to be the one of the highest value traditional foods. Some subsistence Dugong hunting is also allowed in the Pacific states of Papua New Guinea (restrictions apply), Vanuatu and New Caledonia (restrictions apply), where Dugongs are still of great cultural and dietary significance.Commercial exploitation of Dugongs occurred intermittently at various places along the coast of Queensland, Australia, from 1847-1969 (Daley et al. 2008). Numerous products are still obtained from Dugongs and used for food, folk medicine, cooking/lubrication, aphrodisiacs, amulets/charms/jewellery, carvings, religious artefacts, leather products and other (Marsh et al. 2011). Trade in Dugong (and all other sirenian) products is regulated or banned by the Convention for Trade in Endangered Species (CITES). Dugongs are currently listed on CITES Appendix I.|
Threats to Dugongs vary between different populations as detailed in Marsh et al. (2011) and Hines et al. (2012). Major threats include:
Climate change is projected to lead to altered coastal environmental condition and increases in severe tropical storms and flood events that could affect both Dugongs and their seagrass habitats exacerbating the effects of the other drivers listed above (see Marsh et al. 2011 for details).
Dugongs are covered under three international conservation conventions: 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 (also known as CMS or the Bonn Convention). Dugongs are also included in the Coral Triangle Initiative (CTI), goal five (Threatened Species). Additionally, the Convention on Wetlands (the Ramsar Convention) protects some important Dugong habitats.
To date, there has been little effective management intervention to reduce anthropogenic impacts on the Dugong, apart from legislative protection which is almost ubiquitous throughout its range. Protected area initiatives aim to protect Dugongs in many range states (Marsh et al. 2011) and are most developed in Australia. Most of the marine protected areas outside Australia with the potential to protect Dugongs are ‘paper parks’ where laws and regulations exist but are not implemented. Strategic Action Programmes/Strategic Plans/Action Plans to protect Dugongs have been developed by countries in the Red Sea and Gulf of Aden region (Gerges 2002), Indonesia (de Iongh et al. 2009a, 2009b) and South Pacific Regional Environmental Programme (SPREP; Gillespies 2005). However, effective enforcement of conservation regulations is a problem throughout most of the region because of poverty, lack of resources and personnel. The most pressing need is for alternative sustainable livelihoods that address poverty and provide incentives for conservation. The most promising initiative is the UNEP Dugong, Seagrass & Coastal Communities Initiative (see http://www.cms.int/en/publication/dugong-seagrass-and-coastal-communities-initiative).
Batista, V.S., Fabré, N.N , Malhado A.C.M. and Ladle, R.J. 2014. Tropical Artisanal Coastal Fisheries: Challenges and Future Directions. Reviews in Fisheries Science & Aquaculture 22: 1-15.
Blair, D., McMahon, A., McDonald, B., Tikel, D., Waycott, M. and Marsh, H. 2014. Pleistocene sea level fluctuations and the phylogeography of the dugong in Australian waters. Marine Mammal Science 30(1): 104-121.
Cheke, A.S. 1987. An ecological history of the Mascarene Islands, with particular reference to extinctions and introductions of land vertebrates. In: Diamond, A.W. (ed.), Studies of Mascarene island birds, pp. 5-89. Cambridge University Press, Cambridge, U.K.
Chuenpagdee, R., Nielsen, J., Dodson, J.J., Friedland, K., Hamon, T.R., Musick, J. and Verspoor, E. 2008. Small is beautiful? A database approach for global assessment of small-scale fisheries: preliminary results and hypotheses. In: Nielson, J. (ed.), Reconciling Fisheries with Conservation: proceedings of the 4th World Fisheries Congress, pp. 587–595. American Fisheries Society, Bethesda, MD.
Cope, R.C., Pollett, P.K., Lanyon, J.M. and Seddon, J.M. 2015. Indirect detection of genetic dispersal (movement and breeding events) through pedigree analysis of dugong populations in southern Queensland, Australia. Biological Conservation 181: 91-101.
Crouch, J., McNiven, I.J., David, B., Rowe, C. and Weisler, M.I. 2007. Marine resource specialisation and environmental change in Torres Strait during the past 4000 years. Archaeology in Oceania 42: 49–64.
Daley, B., Griggs, P., and Marsh, H. 2008. Exploiting marine wildlife in Queensland, the commercial dugong and marine turtle fisheries, 1847-1969. Australian Economic History Review 48: 227-265.
de Iongh, H., Hutosomo, M., Moraal, M. and Kiswara, W. 2009a. National Dugong Conservation Strategy and Action Plan for Indonesia. Part 1 Scientific Report. Institute of Environmental Sciences Leiden and Research Centre for Oceanographic Research, Jakarta.
de Iongh, H., Hutosomo, M., Moraal, M. and Kiswara, W. 2009b. National Dugong Conservation Strategy and Action Plan for Indonesia. Part 2 Strategy Report. Institute of Environmental Sciences Leiden and Research Centre for Oceanographic Research, Jakarta.
Gerges, M.A. 2002. The Red Sea and Gulf of Aden action plan - facing the challenges of an ocean gateway. Ocean and Coastal Management 45: 885–903.
Gillespie, A. 2005. The Dugong Action Plan for the South Pacific: An Evaluation Based on the Need for International and Regional Conservation of Sirenians. Ocean Development and International Law 36: 135–158.
Gredzens, C., Marsh H., Fuentes M.M.P.B., Limpus C.J., Shimada, T. and Hamann, M. 2014. Satellite Tracking of Sympatric Marine Megafauna Can Inform the Biological Basis for Species Co-Management. PLoS ONE 9(6): e98944.
Hines, E., Reynolds, J., Mignucci-Giannoni, A, Aragones, L.V. and Marmontel, M. 2012. Sirenian Conservation: Issues and Strategies in Developing Countries. The University Press of Florida.
Hiraska, K. 1932. The occurrence of the dugong in Formosa. Memoirs of the Faculty of Science and Agriculture, Taihoku Imperial University, Formosa Japan 8: 1-3.
Husar, S. L. 1978. Dugong dugon. Mammalian Species. The American Society of Mammalogists 88: 1-7.
IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: www.iucnredlist.org. (Accessed: 19 November 2015).
Marsh, H., De'ath, G., Gribble, N. and Lane, B. 2005. Historical marine population estimates: triggers or targets for conservation? The dugong case study.
Marsh, H., O’Shea, T.J. and Reynolds III, J.E. 2011. The ecology and conservation of Sirenia: dugongs and manatees. Cambridge University Press.
McDonald, B. 2005. Population genetics of the dugong around Australia: Implications of gene flow and migration. Department of Tropical Biology and Tropical Environment Studies and Geography, James Cook University.
McNiven, I.J. and Bedingfield, A.C. 2008. Past and present marine mammal hunting rates and abundances: dugong (Dugong dugon) evidence from Dabangai Bone Mound, Torres Strait. Journal of Archaeological Science 35: 505–515.
Méry, S., Charpentier, V., Auxiette, G. and Pelle, E. 2009. A dugong bone mound: the Neolothic ritual site on Akab in Umm al-Quwain, United Arab Emirates. Antiquity 83: 696-708.
Moore, J.E., Cox, T.M., Lewison, R.L., Read, A.J., Bjorkland, R., McDonald, S.L., Crowder, L.B., Aruna, E., Ayissi, I., Espeut, P., Joynson-Hicks, C., Pilcher, N., Poonian, C.N.S., Solarin, B. and Kiszka, J. 2010. An interview-based approach to assess marine mammal and sea turtle captures in artisanal fisheries. Biological Conservation 143: 795–805.
Muir, C. and Kiszka, J. 2011. East African dugongs. In: E. Hines, J. Reynolds, A. Mignucci-Giannoni, L. Aragones and M. Marmontel (eds), International Strategies for Manatee and Dugong Conservation, pp. University Press of Florida. Gainesville.
Palmer, D. 2004. Genetic characterization of Thailand Dugongs, implications for conservation. Department of Biological Sciences, San Jose State University.
Pilcher, N.J., Williams, J., Hopkins, G., Hess, D. and Jaouen, L. 2014. CMS-UNEP Questionnaire Survey: Assessment of Dugong Distribution and interactions with small-scale fisheries. CMS-UNEP Office, Abu Dhabi, United Arab Emirates.
Read, A.J., Drinker, P. and Northridge, S. 2006. Bycatch of marine mammals in US and global fisheries. Conservation Biology 20: 163–169.
Robards, M.D. and Reeves R.R. 2011. The global extent and character of marine mammal consumption by humans: 1970–2009. Biological Conservation 144: 2770–2786.
Seddon, J.M., Ovenden, J.R., Sneath, H.L., Broderick, D., Dudgeon, C.L. and Lanyon, J.M. 2014. Fine scale population structure of dugongs (Dugong dugon) implies low gene flow along the southern Queensland coastline. Conservation Genetics 15(6): 1381-1392.
Sheppard, J., Preen, A.R., Marsh, H., Lawler, I.R., Whiting, S. and Jones, R.E. 2006. Movement heterogeneity of dugongs, Dugong dugon (Müller) over large spatial scales. Journal of Experimental Marine Biology & Ecology 334: 64–83.
Sobtzick, S., Hagihara, R., Grech, A. and Marsh, H. 2012. Aerial survey of the urban coast of Queensland to evaluate the response of the dugong population to the widespread effects of the extreme weather events of the summer of 2010-11. Final Report to the Australian Marine Mammal Centre and the National Environment Research Program June 1 2012.
Woinarski, J.C.Z., Burbidge, A.A. and Harrison, P.L. 2014. The Action Plan for Australian Mammals 2012. CSIRO Publishing, Collingwood.
Wright, D. 2011. Mid Holocene maritime economy in the western Torres Strait. Archaeology in Oceania 46: 23-27.
|Citation:||Marsh, H. & Sobtzick, S. 2015. Dugong dugon. The IUCN Red List of Threatened Species 2015: e.T6909A43792211.Downloaded on 22 September 2017.|
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