OCEANS AND ESTUARIES

In 2007, for fish stocks in fisheries managed by the Australian Government, 16 of the 96 principal species assessed (17%) were overfished and/or subject to overfishing. This compares with 4 of the 55 species assessed (7%) in 1997 and 24 of the 83 species assessed (29%) in 2005 (see Endnote 1). Commonwealth-managed fisheries account for about 30% of all Australian fisheries by production volume. In 2002 (the most recent data available) the National Land and Water Resources Audit assessed the condition of about 1,000 estuaries and found that 50% were near-pristine, 22% were largely unmodified, 19% had been modified and 9% had been extensively modified (Endnote 2).

ABOUT THESE INDICATORS

Australia's coastal and marine regions support a large range of species, many of them found only in Australian waters. These regions are also important to Australian society and the economy.

At present, this dimension has no single headline indicator, but it does have important aspects which different organisations have attempted to measure.

One such aspect is the sustainability of fish stocks. Australia's major fisheries target prized species such as lobsters, prawns, abalone and tuna, which, despite modest production tonnage in world terms, are subject to high fishing pressure. Overfishing occurs when the fishing pressure is too heavy to allow the fish population to replenish itself, or when too many small fish are taken, and therefore too few grow to a size that provides the largest yield for that fishery. Overfished species are those for which the current stock is below a reference point set by scientists and managers.

Measuring the condition of estuaries not only reports on the state of our oceans, it also sheds light on how land use in the estuary catchment is affecting the sea. The Estuarine Condition Index, developed by the National Land and Water Resources Audit, provides a snapshot of estuary health. The more modified an estuary, the greater the pressures on it.

SEE ALSO

Oceans and estuaries - Measures of Australia's Progress, 2006
Themes - Environment & Energy
State of the Environment reporting

ENDNOTES


1. The number of fish stocks (that is, species or groups of species) examined each year has generally increased over time although occasionally a stock may be removed from assessment. For further information see Fishery Status Reports 2007: Status of Fish Stocks Managed by the Australian Government from the Bureau of Rural Sciences.

2. National Land and Water Resources Audit 2002, Catchment, River and Estuary Condition in Australia, NLWRA, Canberra.

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