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Compiled by Leon P. Zann
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1995)
ISBN 0 642 17391 5
Little is known of the conservation status of most of Australia's marine species(15). Scientific interest to date has largely centred on the higher vertebrates such as turtles, seabirds, seals, dugongs and whales. Micro-organisms, algae, invertebrates and fish have been generally neglected(85).
Much of the effort in conservation of terrestrial biodiversity has centered around the protection of rare and endangered species. However, it is difficult to apply the endangered species concept to marine animals other than mammals, seabirds and some reptiles. Management strategies for conserving terrestrial species are often not suitable because of the interconnectivity in the marine environment. (15)
Many marine species are naturally rare by terrestrial standards but are not necessarily endangered. Species extinctions appear to be infrequent in the marine environmental but local extinctions are more common. If these occur in ecologically important species in specific communities, they may have a major impact on marine ecosystems. (15)
We know very little of marine biodiversity. Many marine species remain undescribed and relatively little is known about most of the described species. An enormous taxonomic and monitoring effort would be required in Australia to describe all species and to determine their status (15)
Given this lack of knowledge, precautionary management strategies are important on the conservation of marine biodiversity. These strategies might include establishing protected areas for endemic species with small geographic ranges or restricted breeding sites; protecting long-lived, large and wide-ranging species; and enhancing populations of excessively exploited species.(15)
Networks of marine protected areas are an important 'catch all' strategy for protecting the majority of species of unknown status and significance, particularly invertebrates.(15)
The seas around Australia contain thousands of different types of microscopic marine algae, fungi and bacteria. Australia's marine phytoplankton includes representatives of all 13 algal classes, including diatoms (5,000 species) and dinoflagellates (2,000 species)(14). Australia is also very rich in macroalgae or seaweeds. Southern Australia has over 1,150 species. This is over 50% more than any comparable region in the world(88).
The angiosperms (flowering plants) are also very well represented. Australia has 11 of the world's 12 genera of seagrass, and over half the total number of species. Australia has 16 of the world's 20 families of mangroves, and 40 of the world's 55 species of mangroves.(88)
The number of marine invertebrate species in Australia is unknown but is probably in the order of tens of thousands. The conservation status of very few invertebrate species is known. A number appear vulnerable because they are rare and have quite restricted habitats(15). Examples include a number of species of volute shells; cowries such as the Western Australian Zoila species and the Queensland Cymbiola species; and the live-bearing starfish Patiriella vivipara and P. parvivipara which are restricted to Tasmania and South Australia, respectively(84),(89).
Because there is insufficient information on the status of invertebrate species, none are listed in the Commonwealth Endangered Species Protection Act 1992. Some, mainly the commercially fished species, are covered by the Wildlife Protection (Regulations of Exports and Imports) Act 1982. All hard corals (Scleractinia) are listed on Appendix 2 of the Convention on International Trade in Endangered Species (CITES) because of problems in controlling trade in other countries. It is expected that as scientific knowledge increases, the vulnerable invertebrates will be progressively incorporated into the legal and administrative framework used to conserve vertebrates(16),(60). Habitat protection is considered to be the most useful approach to conserving invertebrates(15).
Australia has an estimated 4,000 to 4,500 species of fish, of which around 3,600 have been described. Around one-quarter of the species are endemic, most of which are found in the south(5),(90). While regulations governing many of the fished species have long existed in this country, marine fish conservation is a relatively new field and the conservation status of most species is poorly known(16).
Potentially vulnerable fish include the sharks, which are slow growing, have a low reproduction rate, are highly migratory, and school during the mating season. Threats are commercial and sports fisheries, and shark meshing of surfing beaches. Also vulnerable are fish species with restricted distributions which may be threatened by loss of habitat.(16)
Recent concern has focused on the status of the tropical rays known as sawfish, and the endemic handfish family in southern Tasmania. The handfish Brachionichthys hirsutus is the first marine fish to be listed nationally as endangered.(16)
No marine fish in Australia is listed as 'Endangered' by the IUCN (International Union for the Conservation of Nature - World Conservation Union). One, the whale shark, is listed as 'Indeterminate'. The status of the great white shark and several others is insufficiently known. Other species have been considered for national conservation listings, for example Herbst's shark, black cod and southern bluefin tuna(16).
The grey nurse sharks, harmless fish-eaters despite their fearsome reputation, are protected in New South Wales because populations were seriously depleted by spear fishing. Whale sharks are protected in Ningaloo Marine Park in Western Australia. The leafy sea dragon is protected in South Australia because of concerns that populations were declining, possibly due to trawling, collecting and loss of habitat. The blue groper is protected in parts of South Australia. The black cod, a large species targeted by spear and line fishing, is protected in New South Wales and through the establishment of the National Marine Nature Reserve at Elizabeth and Middleton Reefs in the Tasman Sea(16).
Australia has about 30 of the world's 50 species of sea snakes, around half of which are endemic. The family of aipysurids live in coral reef waters and the family of hydrophiids live in inter-reefal waters of Australia's tropics. Sea snakes bear live young and have a relatively short lifespan; they reach sexual maturity in around three years, and live for some 10 years. The greatest human impact is from prawn trawling. Sea snakes are quite fragile animals and it has been estimated that between 10 and 40% taken in trawls die once released. For the past 20 years trawled sea snakes have been used in a small leather industry. Licences currently limit the take of sea snakes for leather to 20,000 per year.(18)
Turtles are large and exceptionally long-lived reptiles. They are slow to reach maturity; for example it takes about 35 years for green turtles to mature. Turtles may breed only around five times in their lives, making them extremely vulnerable to over- exploitation. Six of the seven world turtle species occur in Australian waters. One, the flatback turtle, is endemic. Breeding migrations may cover hundreds to thousands of kilometres and many turtles breeding in Australia may live around the islands of Papua New Guinea, the south-western Pacific Islands, and Indonesia, making species management difficult.(18)
The major human impacts on Australian breeding turtles while in neighbouring countries are from subsistence and commercial hunting for meat, shells and leather. The main human impacts occurring while turtles are in Australian waters are: mortality of adults in prawn trawls, shark nets and gill nets, and in collisions with speedboats; subsistence hunting by indigenous communities; habitat degradation; and predation on eggs by feral animals.(18)
Figure 29: Status of turtle rookeries in northern Australia and adjacent islands. Some major declines have occurred in populations to the north.
Turtles are seriously threatened worldwide. The leatherback, green, hawksbill and olive ridley are listed as 'Endangered' by the IUCN; the loggerhead is listed as 'Vulnerable'; and the flatback as 'Potentially Vulnerable'. Despite their apparent abundance in this country, populations of green, loggerhead, and hawksbill are declining in Australia, Indonesia/Malaysia and Oceania. Because some species are highly migratory, a regional approach to the management of turtles is important.(18)
There are about 110 species of seabirds belonging to 12 families found in Australia and its external territories. Of these, 76 species breed and spend their entire lives in the region, and the remaining 34 species are regular or occasional visitors.(17)
The conservation status of most species breeding in the region appears to be satisfactory. In cases where seabirds were formerly exploited, for example for oil, food and bait, most populations have recovered satisfactorily(17). The only remaining industry, the harvesting of short-tailed shearwaters, is sustainably managed(84).
Some 14 species or subspecies of Australia's seabirds (13% of the total) are considered by ornithologists to be threatened, largely because their colonies on oceanic islands are few in number and are vulnerable to harvesting and natural disasters. The wandering albatross on Macquarie Island, Abbot's booby on Christmas Island, and the Australian sub-species of the little tern are classified as 'Endangered' under IUCN criteria. Lord Howe's Kermadec petrel and white-bellied storm-petrel, and Christmas Island's Christmas frigatebird are considered 'Vulnerable'.(17)
Problems for sea birds include illegal poaching of adults, chicks and eggs; mortality from bushfires and feral animals; incidental capture of albatrosses and other seabirds by longline fishing; clearing of habitats; and disturbances of nesting colonies by humans and low-flying aircraft. Possibly half of Australia's nesting islands are subject to one or more of these direct human threats.(17)
Treaties on the protection of migratory shorebirds have been signed with Japan and China, and are planned with Russia, Thailand, Indonesia and Papua New Guinea. International management of migratory seabirds is likewise important.(17)