Oceans of Australia Project

The coastline of Australia (excluding its offshore islands) stretches for 34,218km (21,262 mi), making it the world’s largest island by many estimations (Commonwealth of Australia, 2006). Australia’s oceans cover more than 16 million km2 (6.2 million mi2) – which equates to more than double the area of the Australian continent itself (DEWHA, 2008).

Australia’s waters span nearly 60 degrees in latitude from Torres Strait to Antarctica, and 72 degrees in longitude from Cocos (Keeling) Island in the west to Norfolk Island in the east (Zann, 1995). They also encompass all five marine climatic zones: tropical (25 to 31ºc or 77 to 87.8ºF); subtropical (15 to 27ºc or 59 to 80.6ºF); temperate (10 to 25ºc or 50 to 77ºF); subpolar (5 to 10ºc or 25 to 50ºF); and polar (-2 to 5ºc or 28.4to 25ºF). Because of this, Australia’s seas boast a huge diversity of geologic and oceanographic features, including deep ocean basins, tropical coral reefs, temperate rocky reefs, submarine canyons, seagrass beds, mangroves, estuaries, and approximately 12,000 islands (DEH 2005). Within this area live thousands of marine species, many of which are unique to Australia and all of which help make Australia the most biodiverse developed nation in the world. (DEWHA)

According to Zann, Australian ocean waters are generally low in nutrients, which also make them relatively low in biological productivity (1995). This is due to a number of factors, including the region’s predomination of low-nutrient tropical water masses; the absence of major upwellings of nutrient-rich deep water; and the low nutrient run-off from the mostly arid mainland. However, some inshore areas are abundant in mangroves, seagrass and coral communities which have adapted to low-nutrient waters. The low nutrient levels also contribute to the country’s relatively low fisheries production.

Despite this, fishing is an important industry in Australia, producing wealth and employment through processing, distribution, recreation and retail activities (AFMA 2009). Covering nearly 9 million km2 (3.5 million mi2), Australia’s fishing zone is the world’s third largest, and supports many fisheries collectively worth more than A$2.5 billion (US$2.25 billion) (CSIRO, 2009).

While Australia’s fisheries are designed to help sustain populations of fish and other marine species, some commercial fisheries, particularly southern bluefin tuna, southern sharks and gemfish, have experienced significant declines (Zann 1995). Reasons for these declines include overfishing, use of non-selective fishing gear, pollution, loss of habitat, and the complexity of Australia's marine jurisdiction, which hinders management of fish stocks.

As Zann has indicated, fishing has direct effects on marine ecosystems – the most significant of which includes overfishing of non-target (or ‘by-catch’) species, which can outnumber the target species by as many as 8 to 1 (1995). Fishing may also cause indirect and very poorly understood effects, such as alterations to food chains and population structures. Increasing pressure from recreational activities such as fishing and collecting is of significant concern, especially near coastal regions.

Consequently, the fisheries management sector is marked by uncertainty. In 2005, the Australian Fisheries Management Authority (AFMA) identified the following major influences as likely to impact on ecological sustainability, fishery economics and organisational resources over the next 5 years:

• Overfished target stocks;
• Excess fishing capacity and effort;
• Economic pressures;
• Resource sharing between commercial and recreational sectors;
• Ecosystem sustainability;
• Adjustment pressures on coastal communities;
• Government policy reviews of fisheries management;
• Cost recovery arrangements;
• Depletion of fish stocks;
• Illegal, unregulated and unreported (IUU) fishing, which are undermining national and regional management efforts;
• The conventions of decisions of Regional Fishery Management Organisations (RFMOs), a number of which Australia is involved in; and
• Market factors – including market prices, production costs and currency exchange rates. (AMFA 2005)

The principal concern regarding the future of Australia’s oceans is climate change. The Commonwealth Scientific and Industrial Research Organisation (CSIRO) predicts that global warming will significantly impact Australia’s ecology and climate (Preston and Jones 2006). Observations since 1961 show that approximately 80% of the heat added to the climate system has been absorbed by the sea, where temperatures have increased to a depth of at least 3,000 metres (9,843 feet) (CSIRO 2008). By 2030, it is estimated that Australia’s sea surface temperature will increase by 0.6-0.9ºC (approximately 33 ºF) in the southern Tasman Sea and off the north-west shelf of Western Australia, and 0.3-0.6ºC (approximately 32.5ºF) elsewhere.

Effects of climate change on marine ecology have already been widely observed (CSIRO 2008). For example, recent warming of tropical waters has precipitated repeated mass coral bleaching on the Great Barrier Reef and elsewhere, an occurrence not seen globally before 1979. Researchers predict that the Great Barrier Reef and reefs around Lord Howe Island could be destroyed as a result of the rise in water temperature (IPCC 2007).

Australian research indicates that climate change holds inevitable implications for societies and economies, especially those in coastal areas, which depend strongly on the ocean and its resources (CSIRO 2008). Coastal communities face risks from rising sea levels, though over a long period based on current estimates (IPCC 2007).

A result of increasing concentration of greenhouse gases in the atmosphere, rising sea levels contribute to erosion and inundation of low-lying coastal areas. They also lead to saltwater intrusion into aquifers, deltas and estuaries, which can impact on coastal ecosystems, water resources, and human settlements. With the majority of the Australian population living near the coast, rising sea levels could affect millions of people (CMAR 2009).

Although rising temperatures have a strong influence on observed changes in Australia’s marine environment, other factors such as fishing, coastal run-off, pollution and ocean acidification also play a significant part, and threaten to reduce decrease ecosystems’ resilience to climate change (CSIRO 2008).

Little data exists on the effects of climate change on Australian oceans, mainly due to a lack of long-term data collection (2008). Because little modelling has been conducted to predict future changes in Australia’s marine ecosystems, this remains a crucial impediment in developing a strategic assessment climate change effects, which will enable appropriate policies and strategies to be established.

Australian Fisheries Management Authority (AAFMA). [Internet]. [updated 2007 Oct 25] [cited 2009 Oct 27]. Available from: http://www.afma.gov.au/default.htm

Commonwealth of Australia. 2005. National Marine Bioregionalisation of Australia: Summary. Canberra: Department of the Environment and Heritage (DEH). p. 7-10.

Commonwealth of Australia. State of the Environment 2006 [Internet]. [updated 2006]. [cited 2009 Oct 26]. Available from: http://www.environment.gov.au/soe/2006/publications/drs/indicator/142/index.html

Commonwealth Scientific and Industrial Research Organisation (CSIRO). Climate change, fisheries and the marine environment [Internet]. [updated 2008 Dec 5] [cited 2009 Oct 25]. Available from: http://www.csiro.au/science/Marine-Climate-Adaptation.html

CSIRO Marine and Atmospheric Research (CMAR). Sea Level Rise: Understanding the past – Improving projections for the future [Internet]. [updated 2008 Oct 28]. [cited 2009 Oct 26]. Available from: http://www.environment.gov.au/coasts/species/index.html

Department of the Environment, Water, Heritage and the Arts (DEWHA). Marine species conservation [Internet]. [updated 2008 Sep 19] [cited 2009 Oct 26]. Available from: http://www.environment.gov.au/coasts/species/index.html

Preston B.L and Jones R.N. 2006. Climate Change Impacts on Australia and the Benefits of Early Action to Reduce Global Greenhouse Gas Emissions. Aspendale: CSIRO.

United Nations Intergovernmental Panel on Climate Change (IPCC). 2007. Climate Change 2007: Fourth Assessment Report of WGIII IPCC. Cambridge: Cambridge University Press.

Zann, P. Our Sea, Our Future: Major findings of the State of the Marine Environment Report for Australia [Internet]. [updated 1995]. Department of the Environment, Sport and Territories; [cited 2009 Oct 25]. Available from: http://www.environment.gov.au/coasts/mbp/publications/general/pubs/nmb.pdf