Dugong — Species Spotlight

A Seagrass-Grazing Marine Mammal Vanishing from Its Western Range

The dugong is a large marine mammal — the only living member of the family Dugongidae and the only strictly-herbivorous marine mammal. It grazes seagrass meadows across the shallow coastal waters of the Indian and western Pacific Oceans, from East Africa to Vanuatu. The IUCN lists the species globally as Vulnerable, but in 2022 it reassessed several regional subpopulations as Critically Endangered — notably the East African subpopulation and the New Caledonia subpopulation — reflecting severe localised declines [Marsh & Sobtzick 2019; IUCN 2022 regional reassessments].

The dugong is ecologically and culturally significant across its range: it is a seagrass-ecosystem engineer, a culturally important species for many Indigenous and coastal communities (including Torres Strait Islander and Aboriginal Australian peoples, for whom traditional dugong hunting is a recognised cultural right under managed frameworks), and a flagship for the conservation of seagrass — one of the planet's most effective carbon-sequestering ecosystems.

Biology and identification

Dugong dugon adults reach 2.4–3 m in length and 250–400 kg [Marsh et al. 2011]. The body is fusiform (torpedo-shaped) with a fluked tail like a whale's (distinguishing dugongs from manatees, which have a paddle-shaped tail), paddle-like forelimbs, no hind limbs, and a distinctive downturned snout adapted for bottom-grazing on seagrass. The species is grey-brown, nearly hairless except for sensory bristles around the mouth.

Dugongs are obligate seagrass specialists, consuming up to 40 kg of seagrass per day and showing preferences for particular seagrass species and the more nutritious, lower-fibre parts of the plant. Their grazing physically disturbs and "cultivates" seagrass meadows in ways that affect meadow composition — making them ecosystem engineers [Marsh et al. 2011].

Reproduction is exceptionally slow: females first breed at 6–17 years, produce a single calf every 2.5–7 years, and have a gestation of ~13–14 months. Lifespan exceeds 70 years (age determined by growth layers in the tusks). This slow life history means dugong populations can sustain only very low levels of additional mortality — a population can decline at even a 1–2% annual additional adult mortality rate.

Habitat and range

Dugongs occupy shallow, protected coastal waters with seagrass meadows across approximately 40 countries and territories in the Indo-West Pacific — from East Africa (Mozambique, Kenya, Tanzania, the Red Sea) through the Persian Gulf, South and Southeast Asia, to northern Australia and the southwest Pacific [Marsh & Sobtzick 2019].

The species' global stronghold is northern Australia, which holds the large majority of the world's dugongs (tens of thousands) in relatively healthy seagrass habitat. Outside Australia, most subpopulations are small, fragmented, and declining — many reduced to remnant groups. The East African and New Caledonian subpopulations were reassessed as Critically Endangered in 2022; several Southeast Asian and Indian Ocean populations are similarly imperilled.

Conservation status

The dugong is listed globally as Vulnerable on the IUCN Red List [Marsh & Sobtzick 2019], with the East African and New Caledonia subpopulations reassessed as Critically Endangered in 2022. It is on CITES Appendix I (most populations) — international commercial trade prohibited. It is also listed on the Convention on Migratory Species (CMS), under which a dedicated Dugong MoU coordinates conservation across 26+ range states.

The Australian population is comparatively secure and is the basis for the species' global Vulnerable (rather than Endangered) listing; the concern is the contrast between healthy Australian numbers and the collapse of most other subpopulations.

Threats

Seagrass habitat loss and degradation is the structural threat. Seagrass meadows are damaged by coastal development, dredging, agricultural and urban runoff (which reduces water clarity and smothers seagrass), trawling, and extreme weather events. Because dugongs are seagrass obligates, seagrass loss directly limits the population. Major seagrass die-offs (e.g., after Cyclone Yasi and flooding in Queensland in 2011) have been followed by documented dugong mortality and reproductive failure [Marsh et al. 2011].

Fisheries bycatch — particularly entanglement in gillnets and shark nets — is a leading direct mortality source across the species' range. Dugongs surface to breathe and drown when entangled. Gillnet fisheries in dugong habitat across Southeast Asia, the Indian Ocean, and East Africa are a principal cause of the regional declines.

Boat strikes — like manatees, dugongs feeding near the surface in coastal waters are vulnerable to vessel collisions.

Hunting — traditional and illegal hunting for meat, oil, and (in some cultures) tusks. In Australia, traditional hunting by Indigenous communities is a recognised cultural right managed under co-management frameworks; elsewhere, unregulated hunting contributes to decline.

Climate change — affects seagrass distribution and the extreme-weather events that cause seagrass die-offs; warming and sea-level change have uncertain long-term effects on the shallow coastal meadows dugongs require.

What is being done

CMS Dugong MoU — the Memorandum of Understanding on the Conservation and Management of Dugongs and their Habitats, coordinating conservation across 26+ range states, with a Standardised Dugong Catch/Bycatch Questionnaire and seagrass-monitoring programs.
Australian management — Great Barrier Reef Marine Park dugong-protection areas, gillnet restrictions in dugong habitat, Indigenous co-management of traditional hunting (Traditional Use of Marine Resources Agreements), and the world's most comprehensive dugong aerial-survey program.
Seagrass-Watch and seagrass restoration programs — community and scientific monitoring of seagrass health across the Indo-Pacific, since seagrass is the binding constraint on dugong populations.
Regional NGO work — the Mozambique Bazaruto Archipelago dugong population (East Africa's last viable group) is the focus of targeted protection by the Endangered Wildlife Trust, WWF, and partners.
Project Dugong / Dugong & Seagrass Conservation Project — a GEF-funded, UNEP/CMS-implemented program working across eight range countries on seagrass and dugong conservation with community incentives.

How readers can help

Support seagrass conservation — because dugongs are seagrass obligates, protecting and restoring seagrass meadows is functionally equivalent to protecting dugongs. Seagrass is also a major blue-carbon ecosystem, so this work has climate co-benefits. Organizations: Project Seagrass, the CMS Dugong & Seagrass Conservation Project.
Support gillnet-bycatch reduction. Entanglement is a leading direct mortality cause. NGOs working on alternative fishing gear and gillnet restrictions in dugong habitat (particularly in East Africa and Southeast Asia) address the most-immediate threat.
Choose responsible seafood. Avoid wild-caught seafood from gillnet fisheries operating in dugong habitat; MSC certification and Seafood Watch ratings flag high-bycatch fisheries.
For coastal travellers in dugong range (Australia, the Red Sea, East Africa, the Persian Gulf): choose ethical wildlife-viewing operators, never chase or crowd dugongs, and reduce boat speed in seagrass areas.
Support the Bazaruto (Mozambique) dugong protection work specifically — it protects East Africa's last viable dugong population, now Critically Endangered.
Support climate and water-quality policy. Seagrass die-offs are driven by runoff, dredging, and extreme weather; coastal water-quality regulation and climate mitigation protect the meadows.

Last verified: 2026-05-24 Conservation status: Vulnerable globally (IUCN Red List 2019 assessment); East African and New Caledonia subpopulations Critically Endangered (2022); CITES Appendix I; CMS Dugong MoU.

References

Marsh, H., O'Shea, T. J., & Reynolds, J. E. III (2011). Ecology and Conservation of the Sirenia: Dugongs and Manatees. Cambridge University Press.
Marsh, H., & Sobtzick, S. (2019). Dugong dugon. IUCN Red List of Threatened Species. e.T6909A160756767.
CMS (2024). Memorandum of Understanding on the Conservation and Management of Dugongs and their Habitats. Convention on Migratory Species. https://www.cms.int/dugong/
UNEP/CMS Dugong & Seagrass Conservation Project (2024). Programme summary. Global Environment Facility.