Coasts and Oceans Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Australian State of the Environment Committee, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06751 5
Habitats and species (continued)
Fish [CO Indicators 1.1and 3.6]
All species of fish have ecological as well as commercial or recreational significance and some are threatened or endangered. Fish species that are commercially harvested or fished recreationally are discussed in the fisheries section (see Fisheries). Only a few hundred species of Australia's fish fauna are harvested in commercial fisheries; the majority of species (several thousand) are not harvested.
Australia has an estimated 4000 to 5000 species of finfish, of which about 80 to 90% have been described. About one-quarter of these species are found only in Australian waters. New species of fish have been discovered in Australia's EEZ, in particular in the upper continental slope (200 to 400 metre depth). However, very little is known about fish species below 1500 metres depth, which comprises the majority of Australia's marine area.
Under the EPBC Act a threatened species may be listed as:
- critically endangered,
- endangered, or
- vulnerable.
The Threatened Species Scientific Committee has outlined criteria that describe each of these categories (http://www.ea.gov.au/biodiversity/threaten/nominations [accessed 5 September 2001]).
It is a requirement of the EPBC Act to prepare recovery plans for all endangered and vulnerable species that occur in Commonwealth areas. The recovery plan must provide for the research and management actions necessary to stop the decline of the species so that its chances of long-term survival in nature are maximised.
| Endangered marine fish | |
| Brachionichthys hirsutus | Spotted Handfish |
| Vulnerable marine fish | |
| Carcharodon carcharias | Great White Shark |
| Carcharias taurus | Grey Nurse Shark |
| Glyphis sp. A (cf Glyphis glyphis) | Speartooth Shark |
| Sympterichthys sp. [CSIRO #T6.01] | Ziebell's Handfish |
| Sympterichthys sp. {CSIRO #T1996.01] | Waterfall Bay Handfish |
| Vulnerable freshwater fish with a marine life stage | |
| Pristis microdon | Freshwater Sawfish |
| Prototroctes maraena | Australian Grayling |
One of the pressures on sharks and other fish species is shark netting at beaches. Victims of this practice include the Grey Nurse Shark (now thought to be reduced to 1000 individuals), turtles, dolphins, whales and Dugongs. Queensland estimates (EPA 1999a) are that in the last five years fewer than eight turtles died in the nets, 70 being released each year. Information from New South Wales indicates that, over a period of five years, from 1995 until April 2000, shark nets at New South Wales beaches killed 535 sharks and 203 other species. Another 45 sharks and 231 other species were released from shark nets (Davey 2000). The other species included rays, finfish, dolphins, seals, turtles and whales.
A recovery plan has been prepared for the Spotted Handfish and draft (as at May 2001) plans for the Great White Shark and the Grey Nurse Shark. There is an action plan for the Australian Grayling.
The Great White Shark is relatively uncommon in Australian waters, although its range extends primarily from Moreton Bay in Southern Queensland, around the southern coastline to the North West Cape of Western Australia.
White Sharks are primarily a coastal species and often enter very shallow water in search of prey. They differ from most other sharks in that they are warm-bodied, which has helped them become dominant predators in cool and cold environments.
Great White Sharks are naturally not abundant, are reasonably long-lived, and have low natural mortality and low birth rate. These characteristics mean that Great White Shark populations are poorly adapted to withstand increases in mortality from non-natural sources and, due to their low reproductive potential, would recover slowly if reduced in abundance.
There are no reliable estimates of the number of Great White Sharks in Australian waters. Following international concerns about reported declines in Great White Shark populations, they were listed as vulnerable under the EPBC Act in 1997.
The Great White Shark - a vulnerable species.
Source: B Bruce, CSIRO Marine Research
The Great White Shark is now protected in all Australian State and Commonwealth waters. The Commonwealth Government has developed a draft recovery plan (as at May 2001). It is fully protected in Tasmania, South Australia and Victoria; commercially protected in Western Australia; and protected in New South Wales and Queensland, but with exemptions for beach meshing operations. Additional listings under State threatened species legislation is being considered by Tasmania and Victoria.
With initial funding of $100 000 from the Natural Heritage Trust, CSIRO and a number of agencies and groups have joined forces to collect information about Great White Sharks in Australian waters. The study, begun in 1999, aims to clarify the current population status and to understand the behaviour of the sharks. A juvenile great white, nicknamed Neale, was tagged in March 2001 (http://www.marine.csiro.au/research/pelagic/tagging/neale/index.htm [accessed 5 September 2001]) to enable scientists to track daily and seasonal movement patterns. The information will enable more informed decision-making on white shark conservation management in Australia. However, Neale's tag ceased to transmit in July 2001.
Tagged shark.
Source: B Bruce, CSIRO Marine Research
Handfish are small, unusual, slow fish that prefer to ' walk' on their pectoral and pelvic fins rather than swim. The pectoral or side fins are leg-like, with their extremities resembling a human hand (hence their common name).
Handfish are found only in Australia, and generally have very limited ranges. The Spotted Handfish is endemic to the Derwent River. It is considered to be at risk due to its very restricted and patchy distribution, low population density, limited dispersal capacity, and a reproductive strategy producing low numbers of eggs that are highly susceptible to disturbance. The eggs are usually laid around the base of a stalked ascidian (sea squirt).
Spotted Handfish were commonly sighted in the Derwent during the 1960s and 1970s. By 1989 researchers failed to locate any in areas previously renowned for sightings. Subsequently, only two were reliably reported between 1990 and 1994. These results were the first indication that Spotted Handfish had suffered a substantial decline in abundance during the 1980s. The cause of the decline is unclear, but may be connected with its unusual spawning habitat.
All Tasmanian Spotted Handfish are now legally protected, and the species is protected under the EPBC Act.
In March 1996 a recovery team involving many organisations was formed to coordinate research and management of the Spotted Handfish. A collaborative research program between CSIRO and the Tasmanian Aquaculture and Fisheries Institute (TAFI) was successful in spawning and rearing Spotted Handfish.
The recovery plan was completed in March 1998 and actions were initiated in 1999 with funds from the Natural Heritage Trust. The plan includes a variety of strategies, including the use of artificial spawning substrates in the wild.
The Spotted Handfish.
Source: M Green, CSIRO Marine Research
Seahorses
Seahorses are found in most of the world's temperate and tropical coastal waters. Seahorses are considered a curiosity: not only is their appearance unusual, but it is the male which becomes 'pregnant' when a female deposits her eggs into his pouch. Seahorses are caught, particularly in Asia but also in Australia, for traditional Chinese medicines and the aquarium trade.
Leafy Sea-dragon, found only in southern Australian waters.
Source: D Muirhead, Marine Life Society of South Australia Inc
The families Syngnathidae (seahorses, sea-dragons and pipefish) and Solenostomidae (ghost pipefish), of which there are 117 species in Australian waters, are nationally listed marine species. Sea-dragons are found only in southern Australian waters (Figure 9).
Figure 9: Seahorses and pipefish distribution.
Source: Environment Australia (2000)
Syngnathids are long, slender fish with bony plates surrounding their bodies. The name 'syngnathid' refers to their jaws, which are united into a 'tube-snouted' mouth. The two species of sea-dragons, the Leafy Sea-dragon (Phycodurus eques) and the ' Common' or Weedy Sea-dragon (Phyllopteryx taeniolatus), both have many leaf-like appendages on their heads and bodies.
DragonSearch is a Natural Heritage Trust funded program which has gathered distribution information about these little known species through occurrence reports provided by sport and recreational divers (see http://www.dragonsearch.asn.au [accessed 5 September 2001]).
There are controls on taking seahorses in all Australian jurisdictions, for example a prohibition in Commonwealth waters under the EPBC Act. Attempts to culture seahorses in many countries include a successful program in Tasmania.