Ashmore Island (actually composed of three reef islets) is part of Ashmore Reef National Nature Reserve, established in August 1983, and covers 583 sq km (225 sq mi). It is of significant biodiversity value since it lies in the flow of the Indonesian Throughflow ocean current from the Pacific Ocean through the Malay archipelago to the Indian Ocean. It is also in a surface current west from the Arafura Sea and Timor Sea.

The Reserve comprises several marine habitats, including seagrass meadows, intertidal sand flats, coral reef flats, and lagoons, and supports an important and diverse range of species, including 14 species of sea snakes, a population of dugong that may be genetically distinct, a diverse marine invertebrate fauna, and many endemic species, especially of sea snakes and molluscs. There are feeding and nesting sites for various turtle species. It also serves as a bird sanctuary and has 50,000 breeding pairs of various kinds of seabirds. A high abundance and diversity of sea cucumbers, over-exploited on other reefs in the region, is present, with 45 species recorded. 

This astronaut photo from 1992 shows that the reef making up the island is not continuous but has several breaks that allow for current and sediment inflow. Image courtesy of NASA.
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Introduction

Background

Indonesian fishermen have long fished in the area around Ashmore Reef and Cartier Island. British explorers were the first Europeans to see Cartier Island and Ashmore Reef in 1800 and 1811, respectively. American whalers frequently sailed by the islands in the 1850s and later settled to mine the phosphate deposits on Ashmore Reef, which were exhausted by 1891. The UK disputed US access to Ashmore Reef and formally annexed it in 1878. Cartier Island was annexed in 1909. In 1931, the UK transferred the islands to Australia, which accepted them in 1934 as part of Western Australia. In 1938, Australia transferred governance to the Northern Territory. During World War II, the islands saw several Allied ship visits and post-war, Cartier Island became a bombing range. In 1978, governance of Ashmore and Cartier Islands was moved to the federal government. Ashmore Reef and Cartier Island became marine reserves in 1983 and 2000 respectively.

In 1974, Australia and Indonesia signed a memorandum of understanding (MOU) to allow Indonesian fishermen to continue fishing around the islands. The MOU also allows Indonesian fishermen to visit the graves of past fishermen, replenish their fresh water, and shelter in the West Island Lagoon of Ashmore Reef. In the 1990s, Indonesia challenged Australia’s claims to the islands, which was settled in a maritime boundary treaty in 1997. The islands were a popular first point of contact for migrants and refugees seeking to enter Australia, so in 2001, Australia declared the islands outside the Australian migration zone.

Visit the Definitions and Notes page to view a description of each topic.

Geography

Location

Southeastern Asia, islands in the Indian Ocean, midway between northwestern Australia and Timor island; Ashmore Reef is 840 km west of Darwin and 610 km north of Broome; Cartier Islet is 70 km east of Ashmore Reef

Geographic coordinates

12 25 S, 123 20 E

note - Ashmore Reef - 12 14 S, 123 05 E; Cartier Islet - 12 32 S, 123 32 E

Map references

Southeast Asia

Area

total: 5 sq km

land: 5 sq km

water: 0 sq km

note: includes Ashmore Reef (West, Middle, and East Islets) and Cartier Island

country comparison to the world: 254

Area - comparative

about eight times the size of the National Mall in Washington, DC

Land boundaries

total: 0 km

Coastline

74.1 km

Maritime claims

territorial sea: 12 nm

contiguous zone: 24 nm

continental shelf: 200-m depth or to the depth of exploitation

exclusive fishing zone: 200 nm

Climate

tropical

Terrain

low with sand and coral

Elevation

highest point: Cartier Island 5 m

lowest point: Indian Ocean 0 m

Land use

agricultural land: 0% (2018 est.)

Natural hazards

surrounded by shoals and reefs that can pose maritime hazards

Geography - note

Ashmore Reef National Nature Reserve established in August 1983; Cartier Island Marine Reserve established in 2000

Map description

Ashmore and Cartier Islands map showing the islands and reefs that make up this Australian territory in the Indian Ocean.

People and Society

Population

(July 2021 est.) no indigenous inhabitants

note: Indonesian fishermen are allowed access to the lagoon and fresh water at Ashmore Reef's West Island; access to East and Middle Islands is by permit only

Age structure

0-14 years: NA

15-24 years: NA

25-54 years: NA

55-64 years: NA

65 years and over: NA

Dependency ratios

total dependency ratio: NA

youth dependency ratio: NA

elderly dependency ratio: NA

potential support ratio: NA

Death rate

(2021 est.) NA

Drinking water source

improved: urban: NA

rural: NA

total: NA

unimproved: urban: NA

rural: NA

total: NA

Environment

Environment - current issues

illegal killing of protected wildlife by traditional Indonesian fisherman, as well as fishing by non-traditional Indonesian vessels, are ongoing problems; sea level rise, changes in sea temperature, and ocean acidification are concerns; marine debris

Climate

tropical

Land use

agricultural land: 0% (2018 est.)

Government

Country name

conventional long form: Territory of Ashmore and Cartier Islands

conventional short form: Ashmore and Cartier Islands

etymology: named after British Captain Samuel ASHMORE, who first sighted his namesake island in 1811, and after the ship Cartier, from which the second island was discovered in 1800

Dependency status

territory of Australia; administered from Canberra by the Department of Regional Australia, Local Government, Arts and Sport

Legal system

the laws of the Commonwealth of Australia and the laws of the Northern Territory of Australia, where applicable, apply

Citizenship

see Australia

Diplomatic representation in the US

none (territory of Australia)

Diplomatic representation from the US

embassy: none (territory of Australia)

Flag description

the flag of Australia is used

Economy

Economic overview

no economic activity

Transportation

Ports and terminals

none; offshore anchorage only

Military and Security

Military - note

defense is the responsibility of Australia; periodic visits by the Royal Australian Navy and Royal Australian Air Force

Transnational Issues

Disputes - international

Australia-Indonesia:  Australia has closed parts of the Ashmore and Cartier reserve to Indonesian traditional fishing; Indonesian groups challenge Australia's claim to Ashmore Reef