Indicator: CO-02 Number of marine species that are endangered or threatened and changes in population/ distribution of selected threatened species

Data

Number of marine species that are endangered or threatened

See Indicator: BO-02 The conservation status of nationally significant species and ecological communities, compared with previous years

Population and distribution of selected threatened marine species: dugongs, whales and turtles

There are relatively little continent-wide, recent and time series data on marine species, even those that are known to be threatened.

Densities of threatened marine species (less than 14 or greater than 50 threatened species per IMCRA) are shown on the National Marine Atlas.

Threatened Marine Species (PDF - 1430 KB)

Source: National Oceans Office 2006, National Marine Atlas, viewed 29 May 2006, http://www.oceans.gov.au/Non-fish%20Atlas.jsp.

Dugongs

Dugong densities and dugong protection areas continent-wide as at 2004 are shown on Map 20 of the National Marine Atlas. Dugongs are estimated to be distributed over 50,607,207 hectares of marine area, of which 637,122 hectares are dugong protected areas.

Distribution of selected threatened species (PDF - 2000 KB)

Source: National Oceans Office 2006, National Marine Atlas, viewed 29 May 2006, http://www.oceans.gov.au/Non-fish%20Atlas.jsp.

Area where species or species habitat is likely to occur (Dugong)	50,607,209
Total Dugong protection areas	637,122
Dugong protection areas as a proportion of dugong habitat	1%

Source: DEH, unpublished

Torres Strait and the northern waters of the Great Barrier Reef support the largest known populations of Dugong in the world. The largely undisturbed population of Dugong in Shark Bay is the largest intact population of Dugong in the Indian Ocean. In all parts of their range, Dugong populations are under pressure, and in some places they have already been eliminated

Most other available data on dugongs are from the Great Barrier Reef. Aerial surveys of dugong populations, commissioned by the Great Barrier Reef Marine Park Authority (GBRMPA), are carried out by James Cook University since 1984. The number of dugongs in the Great Barrier Reef north of Cooktown has remained stable since surveys started in 1986. However, between 1986 and 1994, the surveys detected a significant population decline from an estimated 3480 (+/- 460) to an estimated 1680 (+/- 240) within eight years.

The results of the 1999 surveys (3993 +/- 644) showed that numbers in the southern area were back at 1986-87 levels probably as a result of dugongs moving into the survey area from other parts of their range in Australia.

An analysis of dugongs caught unintentionally in shark nets at bathing beaches indicates that the catch per unit effort in the nets has fallen to about 3% of the initial catch rates. This evidence may support anecdotal information that the dugong population along the urban coast of Queensland has declined since the 1960s.

Data from these surveys are not available. No more recent data on dugong population and distribution are available.

Whales

Migration paths and other significant areas for various species of whale as at 2004 are shown on the National Marine Atlas.

Distribution of selected threatened species (PDF - 2000 KB)

Source: National Oceans Office 2006, National Marine Atlas, viewed 29 May 2006, http://www.oceans.gov.au/Non-fish Atlas.jsp.

The Marine Atlas estimates of whale distribution (date of data provided to the Atlas is unknown) can be compared to more recent estimates. In all cases, whale distribution appears to have declined since the Atlas data was collected.

Changes in Area of whale activity 2001 to 2005
	Area estimated by NOO for Marine Atlas	Area estimated by NOO in 2005	Difference in hectares	Area of similarity as a percentage of Atlas area
Humpback whales	16,813,738	16,146,437	667,301	96
Blue whales	6,468,107	3,200,110	3,267,997	49
Southern Right whales	11,793,913	2,225,967	9567,946	19
Total	35,075,758	21,572,514	13,503,244	62

Source: Derived from unpublished DEH data

The Humpback Whale Recovery Plan for 2005 - 2010 estimates that in 1999, the west coast population of humpback whales was estimated to be between 8,000 and 14,000 individuals with a rate of increase of approximately 10.14% from 1982 to 1994. In 1999, the east coast population was estimated to be 3,160-4,040 individuals with a rate of increase of approximately 10.9% from 1978 to 1999. It is likely that these rates of increase will fall as the populations near maximum abundance. (http://www.deh.gov.au/biodiversity/threatened/publications/recovery/m-novaeangliae/index.html)

Most other available data on whales and dolphins are from the Great Barrier Reef.

Over 30 species of whales and dolphins visit or are resident in the Great Barrier Reef, including:

Humpback whale
dwarf minke whale
bottlenose dolphin
spinner dolphin
Bryde’s whale
pan-tropical spotted dolphin
false killer whale
killer whale
short-finned pilot whale
sperm whale; and
various beaked whales.

Very little is known of the status of these species in the Great Barrier Reef, other than their occurrence in the region.

In Queensland, the humpback whale population is recovering from the large-scale, industrialised whaling activities. The most recent population survey was in 1998. This estimated the population at 4000 animals, with an annual increase of 11% (Vang 2002). Data do not appear to be available on the current populations of other species of whale.

There is not enough information available to assess the conservation status of dolphins in the Great Barrier Reef. Information on sightings of groups of Indo-Pacific humpback dolphins during aerial surveys, suggests that the population may be declining.

Aerial sightings of Irrawaddy dolphins are even fewer, suggesting either that they are relatively uncommon in Australian waters or that they are inadequately sampled by aerial surveys (Parra et al. 2002). Current research (G. Parra, James Cook University) is looking at populations in the central and northern Great Barrier Reef, using boat-based surveys.

Source: Great Barrier Reef Marine Park Authority 2006, Environmental Status: Marine Mammals - Whales and Dolphins, viewed 23 May 2006, http://www.gbrmpa.gov.au/corp_site/info_services
/publications/sotr/marine_mammals/part_02.html.

Data from these whale surveys are not available. No more recent data on whale population and distribution are available.

Turtles

Again, most of the data is from the Great Barrier Reef. The Great Barrier Reef contains six of the world's seven species of marine turtles. One of these, the flatback turtle, nests only on Australian beaches. All six species of marine turtle are threatened by a variety of human activities and are protected by Commonwealth and State Government legislation.

Of the species for which population trends are known, the loggerhead turtle has declined significantly since 1977 and the green and hawksbill show indications of decline.

Source: Kirstin Dobbs 2001, Marine Turtles in the Great Barrier Reef World Heritage Area: A Compendium of Information and Basis for the Development of Policies and Strategies for the Conservation Of Marine Turtles, Great Barrier Reef Marine Park Authority, viewed 23 May 2006, http://www.gbrmpa.gov.au/corp_site/info_services
/publications/sotr/marine_reptiles/index.html.

The data from which this summary is drawn are not available and data on trends in other marine turtle species do not appear to be available.

Marine Reptiles (Word - 149 KB)

What the data mean

Trends in population and distribution of selected threatened species is limited as an indicator because positive changes in populations of such species may reflect only efforts to save that particular species (for example because of popular attention having been drawn to the issue), rather than improvements in the condition of marine species, habitats and ecosystems more generally. However, the declining range in which particular species are found can be read as broadly indicative of a decline in marine ecosystems.

Much of the data on Trends in population and distribution of selected threatened species are limited to the Great Barrier Reef. However, these also show that several threatened marine species such as dugongs and several species of marine turtle appear to be declining, as are some other species of marine mammal, such as the Indo-Pacific humpback dolphin.

The total number of species that are considered to be threatened has steadily increased since 1993: the listings of these species do not disaggregate whether they are terrestrial and marine. The indicator Number of Threatened Species needs to be treated with caution as an indicator of condition of species and ecosystems. Increases in numbers of listed species may reflect only an increase in scientific knowledge and/or levels of public concern.

Data Limitations

Other than the changes in area where species are found, even in the Great Barrier Reef, where monitoring of some species and populations is relatively intensive, available data on populations and distribution of species are very limited, and time series data even rarer. Data from around the rest of the continent are anecdotal at best.

Issues for which this is an indicator and why

Coasts and Oceans - Condition of the ocean and coastal waters - Condition of species, habitats and ecosystems

Number of threatened species and communities, as represented by the number that have attained legal status as threatened or endangered species, is an ambiguous indicator for loss of biodiversity. However, trends in population and distribution of selected threatened species may be broadly indicative of condition of marine biodiversity more generally.