In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.
|EPBC Act Listing Status||
Listed migratory - Bonn
|Adopted/Made Recovery Plans|
|Other EPBC Act Plans||
Threat abatement plan for the impacts of marine debris on vertebrate marine life (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2009t) [Threat Abatement Plan].
|Policy Statements and Guidelines||
Marine bioregional plan for the North Marine Region (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012x) [Admin Guideline].
Marine bioregional plan for the North-west Marine Region (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012y) [Admin Guideline].
Seagrass - A Vulnerability Assessment for the Great Barrier Reef (Great Barrier Reef Marine Park Authority (GBRMPA), 2011k) [Admin Guideline].
Federal Register of
List of Migratory Species (13/07/2000) (Commonwealth of Australia, 2000b) [Legislative Instrument].
Declaration under section 248 of the Environment Protection and Biodiversity Conservation Act 1999 - List of Marine Species (Commonwealth of Australia, 2000c) [Legislative Instrument].
|State Listing Status||
|Non-statutory Listing Status||
|Scientific name||Dugong dugon |
This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.
|Commonwealth attributions||Connection to APII is unavailable.|
|Other illustrations||Google Images|
The Dugong is a large herbivorous mammal which spends its entire life in the sea. It has paddle-like forelimbs, no hind limbs or dorsal fin, and its tail is broad and horizontally flattened, which it moves up and down to swim. Adults grow to about 2.5-3.5 m long, and weigh about 230-420 kg (Gillespie 2005; PWS 2003). Dugongs have no pinnae (outer ears) (Nishiwaki & Marsh 1985). Dugongs have nostrils near the top of their snouts and surface only to breathe. They are generally solitary, travel in pairs, or associate only in small groups (three to six individuals) (Gillespie 2005).
The Dugong is the only species remaining in the Family Dugongidae and one of only four remaining species in the Order Sirenia. It is most closely related to the extinct Steller's Sea Cow (Hydrodamalis gigas) (Marsh et al 2002).
A significant proportion of the world's Dugongs are found in north Australian waters from Shark Bay, Western Australia, in the west to Moreton Bay, Queensland, in the east (Marsh & Lefebvre 1994). Considerable populations occur throughout this region, particularly in the Gulf of Carpentaria (Northern Territory and Queensland), the northern Queensland coast and the northern Western Australian coast (Marsh et al 2002). The large populations in Shark Bay, Western Australia and the Great Barrier Reef, northern Queensland were noted as one of the natural features associated with World Heritage listing of these areas (DASETT 1990). Dugongs are considered occasional visitors to NSW coastal and estuarine waters (Allen et al 2004).
The extent of occurrence for the Dugong in Australia is estimated at approximately 500 000 km2, based on an interim distribution of non-reef areas north of Shark Bay, Western Australia and Moreton Bay, Queensland with a depth of up to 40 m.
Marsh and colleagues (2002) reported on over ten distinct regions of occurrence of the Dugong in Australia, including four areas in Western Australia; three to four areas in the Gulf of Carpentaria (Northern Territory and Queensland); the Torres Strait and northern Great Barrier Reef regions; and several areas off the urban coast of Queensland.
Specific areas supporting Dugongs in Western Australia include: Shark Bay; Ningaloo Marine Park and Exmouth Gulf; Pilbara Coastal and Offshore regions (Exmouth Gulf to De Grey River); and Eighty Mile Beach and Kimberley Coast Region (Marsh et al 2002).
Gulf of Carpentaria - Northern Territory and Queensland
Areas within the Gulf of Carpentaria region include: the North Coast (Daly River to Milingimbi); the Gulf of Carpentaria Coast of the Northern Territory; and the Gulf of Carpentaria Coast of Queensland. Within the Gulf of Carpentaria Coast of the Northern Territory, the Sir Edward Pellew Islands and the mouth of the Limmen Bight River are the most important areas of the Northern Territory and constitute the fourth most important site in Australia (Marsh et al 2002). Marsh and colleagues (2002) recognise the area between Cape Londonderry and the Daly River as a potential Dugong area.
Torres Strait and northern Great Barrier Reef
The Torres Strait region is the most important Dugong habitat in the world (Marsh et al 2002), while the northern Great Barrier Reef region (from Hunter Point to Cape Bedford near Cooktown, Queensland) is the most important Dugong location within the Great Barrier Reef Marine Park and one of the most important locations Australia-wide (Marsh et al 2002). Together these regions contain the largest Dugong population in the world (Marsh et al 2002).
Queensland urban coast
On the urban coast of Queensland, ranging from Cooktown to the Queensland/NSW border, the most important areas are around Hinchinbrook Island, Cleveland Bay and Shoalwater Bay in the Great Barrier Reef, and Hervey Bay and Moreton Bay further south (Marsh et al 2002). In the Moreton Bay area, the eastern Amity Banks, Moreton Banks and areas adjacent to these sandbanks are considered the most critical Dugong areas (Marsh et al 2002), with Rous Channel and east of South Passage (up to 10 m offshore from Moreton Island) also important in cooler months (Preen 1992; Lanyon & Morrice 1997 in Marsh et al 2002).
New South Wales (NSW)
Dugongs were sighted in coastal and estuarine waters around Wallis Lake, Port Stephens, Lake Macquarie and Brisbane Water in the summer of 2002/2003 (Allen et al 2004). These areas are associated with some of the largest seagrass beds in NSW, some of which contain the Halophila species preferred by Dugongs. The presence of Dugongs in these areas at this time coincided with warm water temperatures (>18°C) (Allen et al 2004).
The Dugong has a large range that spans some forty countries and includes tropical and subtropical coastal and island waters from east Africa to Vanuatu, between about 26° and 27° north and south of the equator (Nishiwaki & Marsh 1985). In the South Pacific, it is found in Papua New Guinea, Soloman Islands, Vanuatu, New Caledonia, Palau and Australia (Gillespie 2005). It also occurs in the Arabian Gulf, the Red Sea, east and south-east Asia, India and Sri Lanka (Marsh et al 2002). The Dugong's historic distribution was broadly coincident with the tropical Indo-Pacific distribution of its food plants, the phanerogamous (flowering) seagrasses of the families Potamogetonaceae and Hydrocharitaceae (Husar 1978).
It is likely that outside Australia, the Dugong is currently represented by relict populations separated by large areas where it is close to extinction or extinct (Marsh et al 2005). Dugongs remain present at the historical limits of their range, but there appears to be a reduction in the area of occupancy within this range (Marsh et al 2002). The degree to which Dugong numbers have dwindled, and their range fragmented, is not known.
In June 2003, aerial surveys in the coastal waters of New Caledonia estimated the Dugong population at approximately 1800, making this one of the largest populations in the world outside of the Australian and Arabian regions, and the largest concentration of Dugongs in Melanesia (Garrigue et al 2008).
Global population trends
Globally, the population trend for the entire species cannot be comprehensively established with current known information, even in places where there have been extensive quantitative surveys like Australia and the Arabian region. Furthermore, the evidence of large-scale movements at scales greater than those covered by these surveys is increasing. Nevertheless, the anecdotal evidence suggests that throughout much of the Dugong's global range, its area of occupancy has reduced, in some areas to the point of extinction (Marsh et al 2002).
Accidental entanglement in gill and mesh nets set by commercial fishers is considered a major but largely unquantified cause of Dugong mortality in many countries (Perrin et al 1996). Indigenous people of Dugong areas throughout the world hunt Dugongs for their meat and oil, however with the advancements in technology and disruptions in Indigenous culture, the challenges of ensuring the sustainability of this harvest are growing (DEH 2005d). The increase in urbanisation and displacement of humans, particularly in developing countries, has led to the exploitation of resources, including food sources such as Dugongs. Traditional environmental values have been lost in these areas and the Dugongs have become an easy and convenient source of food and income. There is often no legislation or enforcement to halt the situation (Marsh et al 2002).
Over most of its range, the Dugong is known only from incidental sightings, accidental drownings, and the anecdotal reports of fishermen. However, within Australia, intensive aerial surveys have resulted in a more comprehensive knowledge of Australian Dugong distributions (Marsh et al 1999). Regular quantitative surveys have been conducted in Australia since the 1970s (Queensland) and the 1980s (Northern Territory and Western Australia).
In Australia, current survey and analytical methods provide adequate knowledge of broad-scale changes in Dugong populations, however these methods are considered inappropriate to detect localised chronic population declines (Marsh 1995, cited in PWS 2003). Given the potential for such localised population declines, information from all sources that indicates evidence of decline is considered closely (PWS 2003).
Northern Territory surveys
In the Northern Territory, a five-yearly aerial survey monitoring program to monitor the distribution and abundance of Dugong has been incorporated in the 2003-2008 monitoring program (PWS 2003). In addition, a marine habitat mapping program has commenced in the Northern Territory, of which seagrass distribution and abundance mapping is a priority component (PWS 2003). The seagrass in the western Gulf of Carpentaria has already been extensively mapped (PWS 2003).
Queensland and Torres Strait surveys
Aerial surveys of Dugong population in the Great Barrier Reef have been carried out by James Cook University on behalf of the Great Barrier Reef Marine Park Authority since 1984 (SOEC 2006).
In 2006, the combined northern Great Barrier Reef (from Cooktown, Queensland) and Torres Strait areas were surveyed concurrently, providing for the first time an estimate of Dugong population for the entire region unconfounded by the effects of Dugong movement between these areas (Marsh et al 2007).
Dedicated aerial surveys of populations indicate that Dugongs are the most abundant marine mammal in the inshore waters of northern Australia (Marsh, unpublished data). Although some suitable habitat has not been surveyed, the population is estimated at about 85 000 Dugongs (Bryden et al 1998; Marsh et al 1999). These are likely to be underestimates as the correction for the number of animals not visible to observers due to water turbidity is probably conservative (Marsh & Sinclair 1989a, 1989b).
In Western Australia, aerial surveys performed during 1989 and again in 1994 resulted in minimal population estimates of 10 000 animals recorded in Shark Bay, and 1000 in the Ningaloo Marine Park and Exmouth Gulf (Marsh et al 2002). Following supplementary aerial surveys in 1999, Gales and colleagues (2004) reported estimates of less than 200 individuals for each of Exmouth Gulf and Ningaloo Reef and 14 000 for Shark Bay. This is an overall population increase within the area which contributed to a distributional shift of animals to the south. It has been hypothesised that the regional change from Ningaloo Reef/Exmouth Gulf region to Shark Bay is a species response to the impact Tropical Cyclone Vance - which passed through the middle of the Exmouth Gulf in March 1999 - had on available forage in the northern habitat (Gales et al 2004).
Northern Territory populations
Surveys have indicated that a significant Dugong population exists in the Northern Territory (PWS 2003). The distribution of Dugongs is patchy in the western areas and quite uniform in the east, towards the Gulf of Carpentaria (PWS 2003). Apart from a major aggregation of about 4400 animals occurring in Commonwealth and Territory waters seaward of the Tiwi Islands, the majority of other sightings occur within the territorial waters of the Northern Territory (PWS 2003). The Cobourg Peninsula/Croker Island area contains the second largest population in the Northern Territory (approximately 5500 animals) (Saalfield 2000, cited in PWS 2003). The whole northern coastline of the Northern Territory (from Daly River to Milingimbi) has been estimated at supporting over 13 000 animals (Marsh et al 2002).
In the western Gulf of Carpentaria, medium to high densities were sighted along almost the entire coastline. Saalfield (2000) (cited in PWS 2003) estimates that about 8000 Dugongs occur from the Limmen Bight River to east of the Sir Edward Pellew Group of Islands - making it the largest Dugong population in the Northern Territory - and about another 4000 Dugongs occur in the Blue Mud Bay area, with about 16 000 occurring in total (Marsh et al 2002).
The populations in the Tiwi Islands, Cobourg Peninsula/Croker Island area, Limmen Bight River to Sir Edward Pellew island group and the Blue Mud Bay area all rank within the top eight Dugong populations in Australia.
Gulf of Carpentaria
In the eastern Gulf of Carpentaria, survey results have indicated that this area supports Queensland's third largest population of Dugong (approximately 4000 animals), and is among the six most important Dugong habitats in Australia (Marsh et al 2002).
Torres Strait and northern Great Barrier Reef
In Queensland, previous surveys estimated that between 13 000 and 27 000 animals occurred in the Torres Strait and some 9000 in the northern Great Barrier Reef region (Marsh et al 2002). Marsh and colleagues (2007) indicate that the results of surveys in these regions have previously been difficult to interpret because of the potentially confounding influences of unpredictable Dugong movements between areas within the regions. However, the results of surveys undertaken in 2006 concurrently across this entire region suggest a total population of around 20 600 to 26 400 (Marsh et al 2007). Studies have also indicated that the fluctuations in estimated population sizes for the Torres Strait region area are unlikely to be due to significant population movements between the Torres Strait and the northern Great Barrier Reef region (Marsh et al 2007). The northern Great Barrier Reef region (from Hunter Point in the north to Cape Bedford near Cooktown further south) has the largest area of seagrass in the Great Barrier Reef and supports one of the largest populations of Dugongs on the eastern Queensland coast (Marsh et al 2002). Seagrass beds in this area are remote and subject to a low level of human influence (Marsh et al 2002).
Great Barrier Reef Marine Park
The Dugong population size for the whole of the Great Barrier Reef Marine Park - which extends southwards from the tip of Cape York in Queensland to almost Bundaberg, thereby incorporating areas from the northern Great Barrier Reef and Queensland urban coast regions described above - is estimated at 14 000 animals (Dobbs et al 2008).
Queensland urban coast
Population size for Dugongs on the Queensland urban coast, including the southern part of the Great Barrier Reef and areas further south of the reef, have been difficult to estimate due to large scale movements of Dugongs in the area (Marsh et al 2002). In 1986, numbers of individuals in the area between Hinchinbrook Island (north of Townsville) and the southern boundary of the Great Barrier Reef Marine Park (north of Bundaberg) were estimated at approximately 3500, and in 1994 at 1700 individuals (Marsh et al 2002). In the Hervey Bay-Great Sandy Strait region numbers were estimated at approximately 2200 in 1988, approximately 800 in 1994, and approximately 1600 individuals in 1999; while in the Moreton Bay region numbers were estimated at approximately 450 individuals prior to 1995, compared to around 360 individuals in 2001 (Marsh et al 2002).
Aerial surveys of Dugong populations in Shark Bay in 1989 and 1994 indicate that the population is stable, with further surveys indicating the the distribution within this area varies seasonally (Marsh et al 2002). Surveys in 1989 and 1994 also indicated that populations within the Ningaloo Marine Park and Exmouth Gulf region were stable (Marsh et al 2002). However, surveys in 1999 and 2000 revealed that populations had dwindled, most likely due to the effects of Tropical Cyclone Vance and subsequent movement of Dugongs into Shark Bay (Marsh et al 2002). Little is known about the population trends for the Pilbara Coastal and Offshore Region, Eighty Mile Beach and the Kimberley Coast.
Torres Strait and northern Great Barrier Reef
Aerial surveys since the mid-1980s of the Torres Strait and northern Great Barrier Reef regions have not indicated a decline in Dugong populations of that area (Marsh et al 2007). These results must be interpreted with caution, however, as it has been demonstrated that the ability to detect declines in marine mammal stocks is poor (Marsh et al 2007). In addition, Dugongs in the Torres Strait have been found to be breeding at small sizes and young ages, which may be a sign of population decline (Marsh et al 2007).
Queensland urban coast
Although large-scale movements of Dugongs have made interpretation of long-term trends in abundance in this area difficult, evidence suggests a long-term decline for the Queensland urban coast region with shorter-term fluctuations at more local scales (Marsh et al 2002). Marsh (2000) used records from the government shark control program to hindcast changes in Dugong numbers over the last four decades along a 10° latitude stretch of the urban coast of Queensland, south of Cairns. The catch per unit effort of Dugongs as by-catch suggests that populations have declined to about 3% of their size in the early 1960s in this region. Although population numbers are far below those in the early 1960s, and it is difficult to assess whether populations are stable, increasing or declining (Dobbs et al 2008), numbers for the entire urban coast of Queensland are now considered stable (Marsh & Lawler 2006, cited in Dobbs et al 2008).
New South Wales
While Dugongs are considered only occasional visitors to the NSW coastal waters at present, they may have occurred in greater numbers in NSW prior to European settlement (Troughton 1928, cited in Allen et al. 2004).
Simulations of Dugong populations show that, even with low natural mortality and no human-induced mortality, an increase of more than 5% per year is unlikely due to its low reproductive rate. Thus, in order for numbers to be maintained, adult survivorship must be higher than 95% each year, and even a slight fall of adult survivorship can cause a substantial decline (Marsh et al 2002).
Members of the Order Sirenia, including the Dugong and the three species of manatee, are all herbivores and use fresh water to varying degrees. While Dugongs frequent coastal waters, they also use estuarine creeks and streams and have been tracked travelling within creeks upstream for several kilometres (Lawler et al 2002). Feeding aggregations tend to occur in wide, shallow protected bays; wide, shallow mangrove channels; and in the lee of large inshore islands (Heinsohn et al 1979). These areas are coincident with sizeable seagrass beds. Dugongs are also regularly observed in deeper water further offshore in areas where the continental shelf is wide, shallow and protected. In the Torres Strait, between Australia and Papua New Guinea, significant numbers of Dugongs are seen more than 10 km from land (Marsh & Saalfeld 1989, 1991). Marsh and Saalfeld (1989) have also sighted Dugongs approximately 58 km from the north Queensland coast, in water up to 37 m deep. This distribution reflects that of deepwater seagrasses such as Halophila spinulosa. Dugong feeding trails have been observed at depths of up to 33 m off northeast Queensland (Lee Long et al 1997).
There is evidence that Dugongs use specialised habitats for various activities. Shallow waters, such as on tidal sandbanks (Marsh et al 1984) and estuaries (Hughes & Oxley-Oxland 1971), have been reported as sites for calving. Anderson (1981) suggested that this may be a strategy to avoid sharks. The physical characteristics of South Cove in Shark Bay, Western Australia, may make it especially suitable for the lek mating behaviour (gathering of males for mating display) observed by Anderson (1997). At the higher latitudinal limits to their range, deeper waters may be used as a thermal refuge from cooler inshore waters (Anderson 1986; Marsh et al 1990; Preen 1992).
Dugongs are long-lived with a low reproductive rate, long generation time, and a high investment in each offspring. The oldest Dugong whose tusks have been examined for age determination was estimated to be 73 years old when she died. Marsh and colleagues (1984) estimate that Dugongs over 2.5 m are mature, while those less than 2.2 m are probably immature. Females do not bear their first calf until they are at least 10 and up to 17 years old. Gestation is approximately 13 months. The usual litter size is one. The calf suckles for at least 18 months, and the period between successive calvings is very variable; estimates range from three to seven years. Dugongs start eating seagrasses soon after birth, but they grow rapidly during the suckling period when they also receive milk from their mothers (Marsh 1995a, 1999c).
Although Dugongs breed year round, they show some seasonality, with mating and calving apparently peaking in spring and summer especially in the higher latitude limits of their range (Marsh 1999c). Shallow waters, such as on tidal sandbanks (Marsh et al 1984) and estuaries (Hughes & Oxley-Oxland 1971), have been reported as sites for calving. As noted above, Anderson (1981) suggested that this may be a strategy to avoid sharks. The availability of seagrass is also a factor in reproduction; when there is not enough to eat, Dugongs delay breeding.
Dugong mating behaviour appears to vary spatially. Preen (1989) observed mating herds in Moreton Bay, Queensland, where male Dugongs violently compete for oestrous females, and similar herds have been observed in two localities in north Queensland (Marsh 1999c), where several presumed males attempt to embrace the presumed female, each attempting to mate with her (Preen 1989). In contrast, resident Dugongs in South Cove in Shark Bay, Western Australia, exhibit mating behaviour consistent with the definition of a lek ("in a classic lek males aggregate on mutually exclusive display areas at a traditional site that lacks resources required by females, and females visit this site only in order to mate" (Anderson 1997, p434)). Anderson (1997) observed male Dugongs defending mutually exclusive territories in which unique behaviours were displayed in order to attract females. It is not known whether lekking occurs elsewhere in the Dugong's range, and its significance to the estimated 10 000 Dugongs that live in Shark Bay is uncertain (Marsh et al 1994; Preen et al 1997).
Dugongs are seagrass specialists, uprooting whole plants when they are accessible, but feeding only on leaves when the whole plant cannot be uprooted (Anderson 1982b; Marsh et al 1982, 1999). However, Anderson (1998) claims that his observations in North Cove, Western Australia, suggest that Dugongs selectively forage for Halodule rhizomes. Dugongs prefer seagrasses that are early seral or 'pioneer' species (Preen 1995a, 1995b), especially species of the genera Halophila and Halodule. Diet selection is correlated with the chemical and structural composition of seagrass (Aragones 1996; Lanyon 1991). The most frequently selected species are lowest in fibre and highest in available nitrogen and digestibility (Aragones 1996; Lanyon 1991). Selection for the species that are highly digestible (Halophila spp.) and have high nutrients (Halodule spp.) means that Dugongs maximise the intake of nutrients rather than bulk (Aragones 1996). It is estimated that Dugongs consume between 21-36 kg of seagrass each day (PWS 2003).
Marine algae are also eaten (Marsh et al 1982), but this is believed to occur only when seagrass is scarce (Spain & Heinsohn 1973). Anderson (1989) and Preen (1995a) have evidence that Dugongs may deliberately forage for macro-invertebrates near the southern limits of their range in both western and eastern Australia. However, examination of stomach and faecal samples (Preen 1995a) suggests that Dugongs do not deliberately forage on macro-invertebrates in more tropical areas of Australia.
The highly specialised dietary requirements of the Dugong suggest that only certain seagrass meadows may be suitable as Dugong habitat (Preen 1995b). The total area of seagrass may not be a good indication of its value to Dugongs (Lawler et al 2002). Preen (1995b), De longh (1996) and Aragones and Marsh (1999) suggest that grazing activities by Dugongs alter the species composition of seagrass communities at a local scale. Thus, areas that support sizeable numbers of Dugongs may have the capacity to provide better 'quality' food than areas that support few or no Dugongs and rely only on natural turnover rates for recycling and redistribution of nutrients (Aragones & Marsh 1999). The Dugong's reliance on certain species of seagrass makes them particularly vulnerable to habitat loss.
Dugongs are highly migratory and this is believed to be largely due to their search for suitable seagrass beds or warmer waters (Marsh et al 2002). In Australia, most movements of the more than 60 Dugongs tracked using VHF or satellite transmitters have been localised to the vicinity of seagrass beds (De longh et al 1998; Marsh & Rathbun 1990; Preen 1992). Daily movements depend on tidal amplitude. Where the tidal range is large (e.g. up to 8.5 m in Shoalwater Bay in the Mackay-Capricorn Section of the Great Barrier Reef Marine Park (Anderson & Birtles 1978)), Dugongs can gain access to their inshore feeding areas only when water depth is 1 m or more. Where tidal amplitude is low, such as Shark Bay, Western Australia, (Anderson 1982b) or where seagrass grows subtidally, daily movements are not dictated by tides.
At the high-latitude limits of their range, such as Shark Bay in Western Australia and Moreton Bay in Queensland, there is evidence to suggest that Dugongs make seasonal movements to warmer waters. In Shark Bay, results from studies involving satellite tracking have shown that Dugongs moved over 100 km north-westward to the warmer, western part of that bay during winter and then returned to the eastern part of the bay during the onset of warmer conditions in summer (Anderson 1982b; Anderson 1986; Gales 2002, pers. comm.; Marsh et al 1994; Marsh et al 2002). In winter in Moreton Bay, many Dugongs regularly make a round trip of 15-40 km between foraging grounds inside the bay and oceanic waters, which average up to 5°C warmer (Preen 1992).
At least some individual Dugongs undertake long-distance movements. An adult female moved 600 km between two sites in the Gulf of Carpentaria over about five days (Preen 1995c). Another male travelled between two localities in the Central Section of the Great Barrier Reef, a straight-line distance of 140 km, three times in six weeks (Marsh & Rathbun 1990). Of the 10 Dugongs fitted with satellite transmitters in Shoalwater Bay, Queensland, by Preen (2001), four made substantial trips out of that bay. Two made return trips: one travelled 100 km north to Clairview; the other 220 km north to Hay Point near Mackay. Two other animals journeyed 400 km south to Hervey Bay. The reasons for such movements are unknown but may be associated with the tendency of their seagrass food to be emphemeral. Results of a time series of aerial surveys in Queensland and Western Australia also suggest large-scale movements of Dugongs between seagrass beds (Marsh & Lawler unpublished, cited in Dobbs et al 2008).
The minimum length of time to detect patterns in Dugong populations is 9–10 years using annual surveys, however long-term trends can be established with 95% confidence with two surveys 10 years apart (Marsh 1989, 1995a).
Accidental entanglement in gill and mesh nets set by commercial fishers is considered a major but largely unquantified cause of Dugong mortality in many countries (Perrin et al 1996), including Australia (Marsh et al 2002). Coates (2002) reported that, over a 15 month period in the Northern Territory, approximately 42% of the total mortality of Dugongs in the Borroloola region was from non-Indigenous causes, including commercial Barramundi fishing (PWS 2003). Dugongs are more likely to be caught in nets in areas where seagrass beds are largely intertidal (e.g. Shoalwater Bay, Queensland).
Shark nets are also a source of Dugong mortality (Marsh et al 2002). Dugong mortality as a result of shark nets has been greatly reduced by the use of baited hooks rather than nets to protect bathers (Marsh et al 2002).
Habitat loss and degradation
The seagrass ecosystems in which Dugongs feed are very sensitive to human influence (Fonseca 1987; Poiner & Peterkin 1996; Shepherd et al 1989). Seagrass beds may be destroyed directly by mining, trawling (Silas & Bastion-Fernando 1985) and natural catastrophic events (PWS 2003), or lost through the effects of disturbances such as dredging, inland and coastal clearing, and land reclamation. These activities cause increases in sedimentation and turbidity which, in turn, lead to degradation through smothering and lack of light. Other threats to seagrass beds include herbicide (Haynes et al 2000) and sewage runoff, detergents, heavy metals, hypersaline water from desalinisation plants and other waste products. Most losses of habitat are caused from reduced light intensity due to sedimentation and/or increased epiphytic growth caused by nutrient enrichment (Marsh et al 2002). In addition, high rainfall can cause increased sediment loads into river systems and adjacent coastal areas.
Lyngbya, a cyanobacterium, is considered to be the biggest challenge to the ecological health of seagrass beds in Moreton Bay, Queensland. Lyngbya blooms smother seagrass, particularly Zostera marina. Intermittent Lyngbya blooms have been reported from Deception Bay (part of Moreton Bay) for several years. In 2000, these blooms extended over parts of the Amity Banks (Limpus 2000, pers. comm.), a favoured Dugong area.
In addition to habitat loss and degradation and incidental catch in gill, mesh and sharks nets, Dugongs are susceptible to a range of other threatening processes (Marsh et al 1999). The relative importance of the various causes affecting Dugong numbers cannot be quantified.
- In Australia, the Dugong has a significant cultural and dietary role for many Indigenous Australian peoples (PWS 2003), and Dugongs are hunted for meat, jewellery and tusks (Marsh et al 2002). In the Northern Territory, the level of Indigenous use and hunting is not adequately known, however, in the Borroloola region, Bradley (1997) (cited in PWS 2003) and Coates (2002) have reported annual harvest levels of 40 to 50 animals. This is less than 20% of the projected sustainable harvest for the region, which is currently at 400 animals, based on an estimated population size of 8000 (Saalfeld 2000, cited in PWS 2003). In the Torres Strait, estimates of harvest levels correlated against population size suggest that the level of Dugong harvesting may not be sustainable (Marsh et al 2002). A study by Marsh and colleagues (2007) indicated that the northern Great Barrier Reef/Torres Strait population was substantial and genetically healthy. However, the study cautions that the ability to detect declines in marine mammal stocks is weak and, thus, lack of detection of decline in abundance does not prove that the present levels of harvest are sustainable.
Boat strike and boating activities
- At present few Dugongs are killed by boats however increasing vessel traffic in Dugong habitat increases their risk. Particularly at risk are regionally important Dugong populations in extensive shallow areas close to areas of high boat traffic (Marsh et al 2002). On the urban coast of Queensland, areas of high recreational use such as the Hinchinbrook Island area, Cleveland Bay, Hervey Bay and Moreton Bay are of greatest concern (Marsh et al 2002). In addition to boat strike, boating activities have the potential to impact on seagrass beds in these areas. In Western Australia, boat strike and habitat disturbance from boating activities is also an issue in high tourism areas such as Shark Bay, Exmouth Gulf and Ningaloo, and on the Pilbara coastal and offshore region where tourism is increasing (Marsh et al 2002).
Tourism - Dugong watching and harrassment
- The precise impact of Dugong watching tours on the species is unknown but is considered a threat to Western Australian and Queensland urban coastal populations, particularly in Shark Bay, Western Australia (Marsh et al 2002). Investigations are underway into the effects of these activities in Western Australia (Marsh et al 2002).
- Dugongs are believed to have acute hearing within narrow sound thresholds (Lawler et al 2002). Acoustic pollution can be caused by vessel traffic, low flying aircraft, seismic surveys and Defence Force activities (primarily underwater detonations). The impact of these on Dugongs needs to be studied further, although there is a preliminary study from Western Australia by the Department of Defence (Marsh et al 2000).
- Several environmental contaminants have the potential to cause harm to Dugongs including: oil from oil spills and the subsequent use of dispersants; heavy metals such as those associated with ports established to load metal ores; and pesticides (Marsh et al 2002). Polychlorinated dibenzodioxins seem to be the most significant ogranchlorine pesticide pollutant bioaccumulated in Dugongs (Marsh et al 2002). The results from liver and blubber tissue analyses from Dugong carcasses stranded along the Queensland coast between 1996–2000 (Haynes et al 2005) showed that octachlorinated dibenzodioxin concentrations were up to twice as high as that found in any other marine mammal (Marsh et al 2002). Other studies revealed that organochlorine levels were similar to those 20 years ago; however, these and other chemicals have been implicated in reproductive and immunological abnormalities in other marine mammals (Marsh et al 2002). The significance of the effects of these types of chemical pollutants on Dugongs requires further investigation (Marsh et al 2002).
Disease and parasites
- Dugongs are susceptible to a wide range of disease including parasitic infestations. Since 1996, 30% of the 80 animals reported to the Queensland Parks and Wildlife Service died from disease (Haines & Limpus 2000, cited in Marsh et al 2002).
- While Dugongs are susceptible to capture stress, the risks associated with catching Dugongs for research are considered low (Marsh et al 2002). While many Dugongs fitted with radio tracking devices appear to have remained unharmed, two out 60 Dugongs caught and fitted with these devices died during capture (Marsh et al 2002). These animals were caught at the southern limit of their range at a time of year when they are typically in the poorest condition.
- Aquaculture is a potential threat as the sites may restrict Dugong feeding grounds and resting refuge access, and interfere with preferred travel routes (Marsh et al 2002).
- Tidal surges from tropical cyclones, for example, cause Dugongs to become stranded (Marsh 1989a). Marsh (1989a) reported the stranding of 27 Dugongs after a tropical cyclone, of which four died and 23 were rescued and released back to sea. However, injuries caused by the stranding event could potentially have killed all of the animals.
Starvation/Loss of seagrass
- Experience from various parts of northern Australia suggests that episodic losses of hundreds of square kilometres of seagrass are associated with extreme weather events such as some cyclones and floods (Poiner & Peterkin 1996). For example, following two floods and a cyclone in early 1992, more than 1000 km² of seagrass were lost from Hervey Bay, Queensland (Preen & Marsh 1995). Between March 1992 and May 1993, a total of 99 Dugong carcasses were recovered in the Hervey Bay area, on the southern and central Queensland coast and along the NSW coast. Most appeared to have been suffering from starvation. This is likely to be a substantial underestimate of the Dugong mortality during this period (Preen & Marsh 1995). In 1995, Cyclone Sandy decimated about 151 km² (20%) of the seagrass area in the Gulf of Carpentaria (Marsh et al 2002).
Marsh and colleagues (2002) noted that the maximum rate of population increase under optimum conditions when natural mortality is low would be around 5% per year, concluding that even a slight reduction in adult survivorship as a result of habitat loss, disease, hunting or incidental drowning in nets, can cause a chronic decline in a population (Marsh et al 2002). The maximum sustainable mortality rate of adult females killed by human activities is around 1 or 2% (Lawler et al 2002), and this rate would need to be lower in areas where food supplies are low (Marsh et al 2002).
The Dugong is fully protected from any form of commercial or recreational exploitation within Australian waters, making it an offence to kill, injure, take, trade, keep or move Dugongs in a Commonwealth area without a permit.
The Native Title Act 1993 and 1998 protects native title holder's rights to non-commercial hunting for subsistence and cultural purposes.
The Sustainable Harvest of Marine Turtles and Dugongs in Australia - A National Partnership Approach (DEH 2005d) is a partnership between the Australian, Western Australian, Northern Territory and Queensland governments and relevant Aboriginal and Torres Strait Islander communities. It was established to support the management of these species while maintaining traditional cultural practices.
The primary protection of seagrass to date has been through marine parks and fishing industry closures to halt trawling that causes structural damage to seagrass beds (Marsh et al 2002).
In 1986, Shark Bay, Western Australia, was closed to mesh netting by Fisheries Western Australia to protect Dugong populations. All other commercial net fisheries are managed on a limited entry basis. Licensing of ecotourism companies that restricts interactions with Dugong and frequency of visits from Monkey Mia, in Shark Bay, also occurs through the Conservation and Land Management Act 1984 (Marsh et al 2002).
In the Northern Territory, the main objectives of the Northern Territory's Draft Management Program for the Dugong are to (PWS 2003):
- identify and encourage protection of important Dugong habitat;
- identify anthropogenic sources of Dugong mortality;
- manage and mitigate identified direct and indirect threats to Dugong and Dugong habitat; and
- develop a monitoring program on Dugong in Northern Territory waters for monitoring of both populations and habitat at all scales.
The management actions accompanying these objectives encompass a range of management, monitoring and sustainable utilisation options which were developed in consultation with Aboriginal people, professional fishers, local communities and various government and non-government organisations. These include the declaration of areas of essential Dugong habitat, and the development of possible fishing regulations, education programs, harvest limits (for Aboriginal communities) and monitoring programs. The monitoring of distribution and abundance of Dugong in the Northern Territory will consist of ongoing aerial surveys at five year intervals (PWS 2003).
Extensive areas of seagrass along the coast have been identified and a number of those supporting high density Dugong populations have been identified as priority conservation and habitat protection areas (PWS 2003).
In 1997, the Northern Territory Fishing Industry Council developed an information kit for licensees to assist with minimising the incidental capture of Dugong in barramundi nets in the Sir Edward Pellew Island region.
Gulf of Carpentaria
In the Gulf of Carpentaria, the Northern Prawn Fishery has closed off specific areas to prawn trawling (Marsh et al 2002).
As part of the North Australian Indigenous Land and Sea Management Alliance (NAILSMA), the Dugong and Marine Turtle Regional Activity Plan for the Southern Gulf of Carpentaria has been developed (NAILSMA 2006). The objectives of this plan are to appoint a coordinator to oversee Dugong conservation projects, provide opportunities for traditional owners to visit Indigenous land and sea management agencies, provide training to traditional owners on Dugong management, develop detailed maps of the southern Gulf of Carpentaria, document important breeding sites for Dugongs as well as hunting areas used by indigenous communities and produce a range of education material for Indigenous communities around the southern Gulf of Carpentaria (NAILSMA 2006).
A marine park has been proposed for the waters around the Wellesley Islands and the Great Barrier Reef Marine Park Authority (GBRMPA) has developed a Dugong Research Strategy (Marsh et al 2002).
The Torres Strait Treaty, signed in 1985, established the Torres Strait Protected Zone, of which a segment is designated as a Dugong sanctuary (Marsh et al 2002).
While aerial surveys conducted since the mid-1980s indicate that Dugong numbers for the entire Queensland urban coast are stable (Marsh & Lawler, cited in Dobbs et al 2008), they are still well below 1960s numbers and Marsh and colleagues (1995) (in Dobbs et al 2008) recommends managing human-related mortality as close as possible to zero. In 1997, the Australian and Queensland governments agreed to several measures aimed at reducing the decline in Dugong numbers along the urban coast of Queensland (Marsh et al 2002).
Throughout the Great Barrier Reef Marine Park, commercial net fishing has been prohibited or restricted, and a series of Dugong Protection Areas have been established (Marsh et al 2002). The GBRMPA has designated approximately 3500 km² of the Park as 'no-take' areas, which either prohibits extraction activities ('Marine National Park' status) or prohibits extraction activities and restricts access ('Preservation' status) (Dobbs et al 2008). For example, the GBRMPA established a 'Preservation Zone' in the northern region of the Marine Park, which is designed to protect Dugong habitat. This area prohibits any extraction activities and strictly controls entry by people. Grech and Marsh (undated) (cited in Dobbs et al 2008) noted that approximately 96% of high conservation value Dugong habitats in the Great Barrier Reef Marine Park are at low risk from key anthropogenic impacts such as mesh gill netting, water quality, Indigenous harvest and boat strike (Dobbs et al 2008).
In the Shoalwater Bay Defence Training Area (~50 km north of Rockhampton, northern Queensland), the potential impacts of defence force activities (primarily underwater detonations) have been minimised by a range of techniques including (URS 2002):
- initial search and mild 'scare-off' techniques using small boats before routine small detonation events (where minimum safe distance areas are under 250 m);
- incremental increases in charge quantities after any time (for example 24 hours or more) of non-activity;
- a safe minimum distance area of 50 m radius for routine charge deployments;
- a larger safe minimum distance area for larger charge detonations;
- the use of delay-causing fuses that link the individual charges and placement of charges in the intertidal holes or channels; and
- avoiding detonations at the peak spring high tide.
In Australia in 2004, the Marine and Coastal Committee (MACC), a body of the Australian Government's Natural Resource Management Ministerial Council (NRMMC), developed a Taskforce on Dugong and Marine Turtle Populations. This Taskforce, which included representatives from a range of Australian Government, State and Territory agencies, developed an approach to ensure the sustainable harvest of Dugongs by Indigenous communities throughout Australia (Sustainable Harvest of Marine Turtles and Dugongs in Australia - A National Partnership Approach). The approach sets out a range of relevant legislative policies, goals and objectives, and suggests a number of actions to ensure this. The goals include (DEH 2005d):
- improve the information base available to Indigenous communities for managing the sustainable harvest of turtles and Dugongs;
- respect for Indigenous and non-Indigenous knowledge and management;
- improve education and awareness;
- identify the economic, social and cultural factors that may contribute to unsustainable harvest levels and identify and implement measures to address them; and
- protect sea country resources.
Outside of Australia, the World Resources Institute suggests that the impacts from coastal development, due to high levels of human population growth and industrialisation, are medium to high. Marsh and colleagues (2002) consider that the long term conservation of the species will depend on conservation strategies, including:
- identifying areas that still support significant numbers of Dugongs; and
- cooperatively working with the community to develop strategies and actions for minimising the impacts upon Dugongs and their habitat (e.g. through management plans).
Marine bioregional plans have been developed for four of Australia's marine regions - South-west, North-west, North and Temperate East. Marine Bioregional Plans will help improve the way decisions are made under the EPBC Act, particularly in relation to the protection of marine biodiversity and the sustainable use of our oceans and their resources by our marine-based industries. Marine Bioregional Plans improve our understanding of Australia's oceans by presenting a consolidated picture of the biophysical characteristics and diversity of marine life. They describe the marine environment and conservation values of each marine region, set out broad biodiversity objectives, identify regional priorities and outline strategies and actions to address these priorities. Click here for more information about marine bioregional plans.
The Dugong has been identified as a conservation value in the North (DSEWPaC 2012x) and North-west (DSEWPaC 2012y) marine regions. See Schedule 2 of the North-west Marine Bioregional Plan (DSEWPaC 2012y) for regional advice. Maps of Biologically Important Areas have been developed for dugong in the North-west (DSEWPaC 2012y) Marine Region and may provide additional relevant information. Go to the conservation values atlas to view the locations of these Biologically Important Areas. The "species group report card - dugongs" for the North (DSEWPaC 2012x) and North-west (DSEWPaC 2012y) marine regions provide additional information.
Research on Dugongs began in Queensland in the 1960s, focussing on anatomy, life history and diet; much of the current knowledge of Dugong-seagrass interactions comes from Queensland studies. Studies on the general ecology and behaviour began in Western Australia in the late 1970s (Marsh et al 2002). Throughout Australia, regular quantitative surveys have been conducted since the 1970s (Queensland) and the 1980s (Northern Territory and Western Australia).
In northern Queensland, between 1998 and 2002, the Department of Defence managed four research studies relating to the impacts of Defence training activities (primarily underwater detonations) on Dugongs in the Shoalwater Bay Training Area (~50 km north of Rockhampton). These studies were (URS 2002):
- Dugong tracking by satellite telemetry;
- an acoustics monitoring study of detonations at Triangular Island;
- a study of Dugong auditory sensitivity by comparative anatomical analysis of Dugong and Manatee heads; and
- low level aerial monitoring of Dugong movements during CD training.
In Queensland, Haynes and colleagues (2005) analysed liver and blubber samples from 53 stranded Dugong carcasses between 1996 and 2000. The livers were analysed for heavy metals and the blubber was analysed for organochlorine compounds. The results suggest that the accumulation of heavy metals and organochlorine is not a significant risk to Great Barrier Reef Dugong populations, however some Dugong tissue may be unsuitable for human consumption due to these elevated levels (Marsh et al 2002).
In 2002, the United Nations Environment Programme (UNEP) published the report: Dugong: Status Report and Action Plans for Countries and Territories, compiled by Marsh and colleagues (Marsh et al 2002), which provides an overview of the status and management of the Dugong globally.
- Sustainable Harvest of Marine Turtles and Dugongs in Australia - A National Partnership Approach (DEH 2005d).
- The Northern Territory Parks and Wildlife Service have developed a Draft Management Program for the Dugong (Dugong dugon) 2003-2008 (PWS 2003).
- The Commonwealth Government ihas developed a Threat Abatement Plan (DEWHA 2009t) to reduce the impact of marine debris on threatened marine species, including Dugongs.
The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.
|Threat Class||Threatening Species||References|
|Agriculture and Aquaculture:Livestock Farming and Grazing:Habitat loss and modification due to clearance of native vegetation and pasture improvements||Commonwealth Listing Advice on Loss of terrestrial climatic habitat caused by anthropogenic emissions of greenhouse gases (Threatened Species Scientific Committee, 2001u) [Listing Advice].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Indigenous hunting and harvesting||Dugong dugon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006hw) [Internet].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Mortality due to capture, entanglement/drowning in nets and fishing lines||Dugong dugon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006hw) [Internet].|
|Ecosystem/Community Stresses:Ecosystem Degradation:Decline in habitat quality||Dugong dugon in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006hw) [Internet].|
|Human Intrusions and Disturbance:Recreational Activities:Environemental pressures due to ecotourism|
|Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Presence of pathogens and resulting disease|
|Pollution:Pollution:Pollution due to oil spills and other chemical pollutants|
|Species Stresses:Species Stresses:unspecified|
|Transportation and Service Corridors:Shipping Lanes:Collision with shipping infrastructure|
2006 Australian State of the Environment Committee (Beeton R.J.S., Buckley, K.I., Jones, G. J., Morgan D., Reichelt R. E. and Trewin, D.) (SOEC) (2006). Australia State of the Environment 2006.
Allen, S., H. Marsh and A. Hodgson (2004). Occurrence and Conservation of the Dugong (Sirenia: Dugongidae) in New South Wales. Proceedings of the Linnean Society of New South Wales. 125:211-216.
Anderson P.K. (1986). Dugongs of Shark Bay, Australia - seasonal migration, water temperature and forage. National Geographic Research. 2:473-490.
Anderson, P.K. (1981). The behaviour of the dugong (Dugong dugon) in relation to conservation and management. Bulletin of Marine Science. 31:640-647.
Anderson, P.K. (1982b). Studies of dugongs at Shark Bay, Western Australia. I. Analysis of population size, dispersion and habitat use on the basis of aerial survey. Australian Wildlife Research. 9:69-84.
Anderson, P.K. (1989). Deliberate foraging on macro-invertebrates by Dugongs. National Geographic Research. 5:4-6.
Anderson, P.K. (1997). Shark Bay dugongs in summer. I: Lek mating. Behaviour. 134(5-6):433-462.
Anderson, P.K. (1998). Shark Bay Dugongs (Dugong dugon) in summer. II: Foragers in a Halodule-dominated Community. Mammalia. 62(3):409-425.
Anderson, P.K. & A. Birtles (1978). Behaviour and ecology of the dugong Dugong dugon (Sirenia): Observations in Shoalwater and Cleveland Bays, Queensland. Australian Wildlife Research. 5:1-23.
Aragones, L. (1996). Dugongs and green turtles: Graziers in the tropical seagrass ecosystem. Page(s) 292. Ph.D. Thesis. James Cook University, Australia.
Bryden, M., H. Marsh & P. Shaughnessy (eds) (1998). Dugongs, Whales and Seals: a Guide to the Sea Mammals of Australasia. Allen & Unwin, St Leonards.
Coates, J. (2002). Sea Turtle and Dugong of the south-west Gulf of Carpentaria: Incorporating traditional knowledge into sustainable resource management. Unpublished report to Environment Australia.
De longh, H.H. (1996). Plant-herbivore interactions between Seagrasses and Dugongs in a Tropical small island ecosystem. Page(s) 205 pp. Roghorst 343: 6708 KX Wageningen, Netherlands.
De longh, H.H., P. Langeveld & M. van der Wal (1998). Movement and home ranges of dugongs around the Lease Islands, East Indonesia. Marine Ecology. 19(3):179-93.
Department of Arts, Sport, Environment, Tourism and Territories (DASETT) (1990). Nomination of Shark Bay, Western Australia. Page(s) 40. Dept of Arts, Sport, Environment, Tourism &Territories, Canberra.
Department of the Environment and Heritage (DEH) (2005d). Sustainable Harvest of Marine Turtles and Dugongs in Australia - A National Partnership Approach. [Online]. The Department of Environment and Heritage, Canberra, Australia. Available from: http://www.environment.gov.au/coasts/publications/turtle-harvest-national-approach.html.
Department of the Environment, Water, Heritage and the Arts (DEWHA) (2009t). Threat abatement plan for the impacts of marine debris on vertebrate marine life. [Online]. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/marine-debris.html.
Dobbs, K., L. Fernandes, S. Slegers, B. Jago, L. Thompson, J. Hall, J. Day, D. Cameron, J. Tanzer, F. Macdonald, H. Marsh & R. Coles (2008). Incoroprating dugong habitats into the marine protected area design for the Great Barrier Reef Marine Park, Queensland, Australia. Ocean & Coastal Management. 51:368-375.
Fonseca, M.S. (1987). The management of seagrass systems. Tropical Coastal Area Management. 2:5-7.
Gales, N. (2002). Personal Communication.
Gales, N., R.D. McCauley, J. Lanyon & D. Holley (2004). Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: Evidence for large-scale migration. Wildlife Research. 31:283-290.
Garrigue, C., N. Patenaude & H. Marsh (2008). Distribution and abundance of the dugong in New Caledonia, southwest Pacific. Marine Mammal Science. 24(1):81-90.
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(2):135-158.
Haynes, D., Carter, S., Gaus, C., Muller, J. & Dennison, W. (2005). Organichlorine and heavy metal concentrations in blubber and liver tissue collected from Queensland (Australia) Dugong (Dugong dugon). Hutchings, P. & Haynes, D., eds. Marine Pollution Bulletin. 51:361-369. Elsevier, Oxford, England.
Haynes, D., J. Muller. & S. Carter (2000). The impact of the herbicide Diuron on photosynthesis in three species of tropical seagrass. Marine Pollution Bulletin. 41:289-293.
Heinsohn, G.E., H. Marsh, B.R. Gardner, A.V. Spain & P.K. Anderson (1979). Aerial Surveys of Dugongs. In: Proceedings of Workshop held in Canberra February 1977. Page(s) 85-96. ANPWS, Canberra.
Holley,D & R. Prince (2008). Historical datasets of dugong (Dugong dugon) observations in the Kimberley region of Western Australia. Dataset Report No. 2008-03. Coastal Marine Ecosystems Research- Edith Cowan University.
Hughes, G.R. & R. Oxley-Oxland (1971). A survey of Dugong (Dugong dugon) in and around Antonio Enes, Northern Mozambique. Biological Conservation. 3:299-301.
Husar, S. (1978). Dugon dugon. Mammalian Species. 88:1-7.
Lanyon, J.M. (1991). The nutritional ecology of the dugong (Dugong dugon) in tropical north Queensland. Page(s) 337. Ph.D. Thesis. Monash University, Australia.
Lawler, I., H. Marsh, B. McDonald & T. Stokes (2002). Current State of Knowledge: Dugongs in the Great Barrier Reef. CRC Reef Research Centre, Townsville.
Lee Long, W.J., L.J. McKenzie & R.J. Coles (1997). Deepwater seagrasses in northeastern Australia - How deep, how meaningful?. In: J. Kuo, R.C. Phillips, D.I. Walker & H. Kirkman, eds. Seagrass Biology: Proceedings of an International Workshop, Rottnest Island, Western Australia, 25-29 January 1996. Page(s) 41-50. University of Western Australia, Perth.
Limpus, C.J. (2000). Personal Communication.
Marsh H., G. De'Ath, N. Gribble & B. Lane (2005). Historical marine population estimates: Triggers or targets for conservation? The dugong case study. Ecological Applications. 15:481-492.
Marsh, H. (1989). Biological basis for managing Dugongs and other large vertebrates in the Great Barrier Reef Marine Park. Unpublished report to the Great Barrier Reef Marine Park Authority.
Marsh, H. (1989a). Mass stranding of Dugong by a tropical cyclone in northern Australia. Marine Mammal Science. 5(1):78-84.
Marsh, H. (1995a). The Life History, pattern of breeding and population dynamics of the Dugong. In: T. J. O'Shea, B. B. Ackermann & H. F. Percival, eds. Population Biology of the Florida Manatee'. Page(s) 75-83. US Department of the Interior, National Biological.
Marsh, H. (1999c). Reproduction in sirenians. In: J.E. Reynolds, III & S.A. Rommel, eds. Biology of Marine Mammals. Page(s) 243-256. Smithsonian Institution Press.
Marsh, H. & D.F. Sinclair (1989a). An experimental evaluation of dugong and sea turtle aerial survey techniques. Australian Wildlife Research. 16:639-650.
Marsh, H. & D.F. Sinclair (1989b). Correcting for visibility bias in strip transect Aerial Surveys of aquatic fauna. Journal of Wildlife Management. 53:1017-1024.
Marsh, H. & G.B. Rathbun (1990). Development and application of conventional and satellite radio-tracking techniques for studying dugong movements and habitat usage. Australian Wildlife Research. 17:83-100.
Marsh, H. & L.W. Lefebvre (1994). Sirenian Status and Conservation efforts. Aquatic Mammals. 20:767-788.
Marsh, H. & Saalfeld, W.H. (1989). The distribution and abundance of dugongs in the northern Great Barrier Reef marine park. Australian Wildlife Research. 16:429-440.
Marsh, H. & W.K. Saalfeld (1991). The status of the Dugong in Torres Strait. In: The status of the Dugong in Torres Strait, ed. Sustainable Development of Traditional Inhabitants of the Torres Strait Region.'. Page(s) 187-194.
Marsh, H., A. Hodgson, I. Lawler, A. Grech & S. Delean (2007). Condition, status and trends and projected futures of the dugong in the Northern Great Barrier Reef and Torres Strait; including identification and evaluation of the key threats and evaluation of available management options to improve its status. Marine and Troical Sciences Research Facility Report Series. Page(s) 77. Reef and Rainforest Research Centre LImited, Cairns.
Marsh, H., C. Eros, P. Corkeron & B. Breen (2000). A Conservation Strategy for Dugongs: Implications of Australian research. Marine and Freshwater Research. 50:979-990.
Marsh, H., Eros, C., Cockeron, P. & Breen, B. (1999). The Dugong, Dugong dugon, in Australia: A Conservation Overview. Page(s) 122. Environment Australia, Canberra.
Marsh, H., G. E. Heinsohn & L. M. Marsh (1984). Breeding cycle, life history and population dynamics of the dugong Dugong dugon (Sirenia: Dugongidae). Australian Journal of Zoology. 32:767-788.
Marsh, H., H. Penrose, C. Eros & J. Hugues (2002). Dugong Status Report and Action Plans for Countries and Territories. United Nations Environment Programme, Nairobi.
Marsh, H., P. J. Corkeron, C. J. Limpus, P. D. Shaughnessy & T. M. Ward (1995). The reptiles and mammals in Australian seas: their status and management, in. In: compiled by Leon P. Zann, ed. State of the marine environment report for Australia: the marine environment - technical annex 1. [Online]. Available from: http://www.environment.gov.au/coasts/publications/somer/annex1/index.html.
Marsh, H., P.W. Channells., G.E. Heinsohn & J. Morissey (1982). Analysis of stomach contents of Dugongs from Queensland. Australian Wildlife Research. 9:55-679.
Marsh, H., R.I.T. Prince, W.K. Saalfeld & R. Shepherd (1994). The distribution and abundance of dugongs in Shark Bay. Wildlife Research. 21:149-61.
Marsh, H., W.K. Saalfeld & A.R. Preen (1990). The distribution and abundance of dugongs in southern Queensland waters: implications for management. Qld Dept. Primary Industries.
McDonald, B. (2005). Population genetics of dugongs around Australia : implications of gene flow and migration. Ph.D. Thesis. James Cook University.
Nishiwaki, M. & H. Marsh (1985). Dugong. (Dugong dugon (Muller, 1776)). In: S.H. Ridgeway & R.J. Harrison, eds. Handbook of Marine Mammals. Page(s) 1-31. Academic Press, London.
North Australian Indigenous Land & Sea Management Alliance (NAILSMA) (2006). Dugong and Turtle Management. [Online]. Available from: http://www.nailsma.org.au/projects/dugong_turtle.html. [Accessed: 29-May-2008].
Parks and Wildlife Service (PWS) (2003). Management program for the Dugong (Dugong dugon) in the Northern Territory of Australia 2003 - 2008. Department of Infrastructure, Planning and Environment, Darwin.
Perrin, W.F., M.L.L. Dolar & M.N.R Alava (1996). Report of the Workshop on the Biology and Conservation of Small Cetaceans and Dugongs of Southeast Asia, Dumaguete, 27-30 June 1995. Bangkok, United Nations Environment Programme.
Poiner, I.R & C. Peterkin (1996). Seagrasses. In: L.P. Zann & P. Kailola, eds. The State of the Marine Environment Report for Australia. Technical Annex: 1. Page(s) 40-45. GBRMPA, Townsville.
Preen, A.R. (1989). Observations of mating behaviour in Dugongs (Dugong dugon). Marine Mammal Science. 5:382.
Preen, A.R. (1992). Interactions between dugongs and seagrasses in a sub-tropical environment. Page(s) 392. Ph.D. Thesis. James Cook University, Townsville.
Preen, A.R. (1995a). Diet of Dugongs:are they omnivores?. Journal of Mammalogy. 76:163-171.
Preen, A.R. (1995b). Impact of dugong foraging on seagrass habitats:observational and experimental evidence for cultivation grazing. Marine Ecology Progress Series. 124:201-13.
Preen, A.R. (1995c). Dugongs, "hot spots" and meta-herds. In: Proceedings of the 1995 Scientific Meeting of the Mammal Society and mammals of the Wet Tropics Symposium. Page(s) 1. Townsville, Qld.
Preen, A.R. (2001). Dugongs in the Shoalwater Bay Area. Report to the Royal Australian Navy.
Preen, A.R. & H. Marsh (1995). Response of Dugongs to large-scale loss of seagrass from Hervey Bay, Queensland, Australia. Wildlife Research. 22:507-519.
Preen, A.R., H. Marsh., I.R. Lawler., R.I.T. Prince & R. Shepherd (1997). Distribution and abundance of dugongs, turtles, dolphins and other megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia. Wildlife Research. 24:507-519.
Shepherd, S.A., A.J. McComb, D.A. Bulthuis, V. Neveravskas, D.A. Steffensen & R. West (1989). Decline of seagrasses. In: A.W.D. Larkum, A.J. McComb & S.A. Shepard, eds. Biology of Australian Seagrasses - An Australian Perspective. Page(s) 364-393. Elsevier, Amsterdam.
Silas, E.G. & Bastion-Fernando, A. (1985). The dugong in India- is it going the way of the dodo?. In: Symposium on Endangered Marine Animals and Marine Parks, Cochin, India, 12-16 January. Page(s) 18. The Marine Biological Association of Indis, Cochin.
Spain, A.V. & Heinsohn, G.E. (1973). Cyclone associated feeding changes in the dugong (Mammalia:Sirenia). Mammalia. 37:678-80.
URS Australia Pty Ltd (2002). Shoalwater Bay Defence Training Area Dugong Research Program: Stage Two Final Report and Recommendations. URS Australia Pty Ltd, Perth, Western Australia.
This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.
Citation: Department of the Environment (2014). Dugong dugon in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Mon, 17 Mar 2014 02:17:43 +1100.