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Home > Local Issues > In The Ocean > PROTECT: Dugongs

PROTECT: Dugongs

The Dugong is listed as Vulnerable by the IUCN RED list

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http://www.iucnredlist.org/apps/redlist/details/6909/0

The dugong’s range spans at least 48 countries and an estimated 140,000 km of coastline. We have used two relatively crude relative indices of extent of occurrence: (1) length of coastline, and (2) area of continental shelf with a depth of <10 m. We then assembled the evidence for all countries in the dugong’s range based on the review of the status of the dugong throughout its range conducted in 2002 with the assistance of more than 100 experts (Marsh et al. 2002) plus additional literature published since that time (see Tables 1.1 and 1.2 in attached PDF). The results of this synthesis are summarized in Table 2.1 (see attached PDF). This synthesis indicates that the dugong is declining or extinct in at least a third of its range, of unknown status in about half its range and possibly stable in the remainder – mainly the remote coasts of the Northern Territory and Western Australia.

The only reference site is the urban coast of Queensland where the most robust quantitative data on population trends are available and a 40 year time series of catch rates in nets set for bather protection indicates that the 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 (unlikely) 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. 

As summarized in Table 2.1, 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 87-99%, subsistence hunting 85-98%, human settlement 82-85%, agricultural pollution 80-89%. 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. There is also anecdotal evidence that the area of occupancy of the dugong has declined in many parts of its range, especially along the coasts of east African and India where anecdotal evidence suggests that it is at high risk of extinction. 

Even in the regions where we have classified the status of the dugong as stable, this classification is unconfirmed. Much of the northern Western Australian and some of the Northern Territory coast has never been surveyed for dugongs and there are no accurate estimates of the Indigenous harvest. The sustainability of this harvest must be questioned as it has been shown to be unsustainable by population modeling in remote parts of Queensland and Torres Strait (Heinsohn et al. 2004, Marsh et al. 2004).

Genetic information on dugong stocks is limited. Recent work based on mitochondrial DNA and microsatellite markers (Brenda McDonald, unpublished data) indicates that the Australian dugong population is not panmictic. There is clear evidence of two maternal lineages, which have a geographical basis apparently reflecting the existence of the Torres Strait land bridge between Australia and PNG, despite the flooding of this land bridge some six thousand years ago. The Australian dugong population still has a fair degree of genetic diversity indicating that recent losses are not yet reflected in the genetic makeup of the population. There is some evidence of gene flow between dugongs in Australia and Eastern Indonesia.

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. Management plans have been developed for some 22-24% of the range (mainly in Australia) but are in place in only 18-22% of the range. The dugong is protected by marine protected areas in 22-23% of its range (again mostly in Australia) (see Table 1.3 in attached PDF). 

Because of the uncertainty associated with the assessment of the status of the dugong both on the Queensland coast based on the CPUE data (Marsh et al. 2005) and the rest of its range, we suggest that the classification should remain as Vulnerable A2bcd.

 

Dugongs facing multiple threats, warns EAD

http://www.khaleejtimes.com/displayarticle.asp?xfile=data/theuae/2011/November/theuae_November142.xml&section=theuae&col=
6 November 2011

ABU DHABI – The dugong (also known as Sea Cow) population in the UAE waters, the world’s second largest home for the marine mammal, is facing multiple threats, the Environment Agency-Abu Dhabi (EAD) warned on Thursday.

 

“The endangered dugong species is currently facing a number of threats due to habitat loss and human-related activities such as increased marine activity, being caught in discarded fishing nets, impact with boats, marine pollution, as well as a decline of its critical natural habitat — underwater sea grass beds,” Thabit Al Abdessalaam, Director of Biodiversity Management Sector at EAD. According to the agency, the world’s second largest population of dugongs is in the UAE waters, and the importance of protecting this unique species is being highlighted in the fifth episode of ‘The Environment Show with Ask Ali’ series. This episode on the dugong is being screened at the Eco-Cinema at the ‘Bu Tinah Experience’ until November 10.

There are only 95,000 to 100,000 dugongs left in the world. Australia has 85,000, the Arabian Gulf and Red Sea bordering countries have approximately 7,300, while the remainder are located in the other range states.

“The protection of Bu Tinah Island and other dugong habitats continues to be a priority for Abu Dhabi. As our country continues to grow and develop, we must ensure that all our biodiversity and natural resources are conserved effectively,” said Al Abdessalaam.  

In this episode of the documentary, viewers get a closer look at the dugong and learn why it has been classified as being ‘vulnerable to extinction’ under the International Union for Conservation of Nature’s (IUCN) 2009 Red List of Threatened Species.

This index indicates how such animals face a high risk of extinction in the wild. During the programme, Ali meets with experts from the EAD who explain the threats facing the species, the importance of its existence to the future sustainability of the UAE’s biodiversity and how Bu Tinah has increasingly become a safe haven for this migratory sea mammal.

The EAD’s Dugong Conservation Programme studies the dugongs’ ecology, movement and migration patterns.  The data collected over the past 10 years has enabled the EAD to better understand the health of the environment and how it should be managed to ensure long-term sustainability.

It has also helped the EAD to understand dugong behaviour and contribute to the establishment of the Marawah Marine Biosphere Reserve.

“We are focused on ensuring that Abu Dhabi’s waters are managed in a manner which helps this globally endangered species. These efforts have enabled us to maintain the species’ population by ensuring the integrity of its key habitats and marine ecosystems,” said Abdessalaam.

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