Tasmania's Threatened Galaxiids
Threatened Species Day fact sheet
Galaxiids are small fish that grow between 35 and 270 millimetres in length. There are approximately 50 Galaxiid species worldwide and of these, 15 of them are found in Tasmania. Ten are endemic to Tasmania – that is, they are found nowhere else in the world.
Four out of ten endemic Galaxiids are listed threatened species under the Environment Protection and Biodiversity Conservation Act 1999. This Act is the main Commonwealth legislation for protecting the environment and conserving biodiversity.
Galaxiids generally have restricted distributions with many found in only a handful of rivers, lakes or swamps. Although restricted in range, Galaxiids inhabit a variety of freshwater habitat types, including streams, lakes and swamps.
Predation by and competition with introduced fish, such as the Brown Trout and Redfin Perch threaten Tasmania's Galaxiids. Fish habitat has also been degraded through damming of rivers, draining and flooding of wetlands and water pollution. Because many Galaxiids have very small distributions they are very vulnerable to any kind of threat or disturbance.
Together with the Australian Government's Natural Heritage Trust, the Tasmanian Government has developed a recovery program to conserve five of Tasmania's most threatened Galaxiids. A number of actions are being undertaken, including establishment of translocated populations, monitoring natural populations, raising public awareness and habitat protection.
Breeding populations of the Pedder and Swan Galaxias have been successfully established. Artificial barriers have been constructed at some sites to protect Swan Galaxias from introduced fish such as trout.
Here's how you can help threatened Galaxiids as well as other threatened fish species:
- declare your land a private reserve or conservation covenant;
- protect native fish habitat by looking after freshwater and streamside environments;
- don't move fish between streams or lakes; and
- report sightings of introduced fish. Contact your local coordinator at the details given below.
The Pedder Galaxias in one of Australia's most endangered fish. Once common, it declined rapidly after Lake Pedder was flooded for hydro-electricity in the 1970's. It is now thought to be extinct in Lake Pedder. Translocation of the species has been successful and a breeding population has now been established in a nearby lake. Attempts are now being made to establish a second breeding population at another nearby dam.
Since the early days of European settlement many freshwater fish species have been introduced to Tasmania, mainly from European countries. The species listed below have become established in the wild in Tasmania and all have major impacts on native fish species through predation, competition, spreading of disease or parasites, or alteration of habitat.
Often referred to as the 'freshwater rabbit' because of how quickly they multiply, Carp are one of Tasmania's worst introduced fish. Carp compete for food and space with native species. Their habit of gulping mud to filter out food muddies clean waterways, disturbs aquatic vegetation and is thought to have caused bank slumping and erosion in a number of mainland rivers.
Carp were first discovered in north-west Tasmania in 1975, and attempts were made to exterminate them. They were rediscovered in 1995 and have since been the subject of a huge and costly eradication program. They are currently thought to be in decline.
Brown, Rainbow and Brook trout are introduced fish species that are widespread in Tasmania. They prey on a number of native fish species and compete with them for food and space but also are very popular among recreational anglers. They are implicated in the decline of a number of Tasmanian Galaxiids. Moving trout into waterways where they have not previously been known can have a devastating impact on our much smaller native fish species.
Also known as Mosquito Fish, Gambusia were discovered in Tasmania in 1991, and although attempts were made to eradicate them they were rediscovered in 2001. Ironically, this fish targets virtually everything other than mosquitoes, with a particular preference for tadpoles and frog's eggs. They are thought to have had severe impacts on many threatened Australian frog species.
Although only growing to about 60 millimetres in length, they are fast growing, tolerant of a wide range of temperatures and salinity, and are highly aggressive. Mosquito Fish also prey on eggs and fry of many native fish species.
For more information about helping threatened species in Tasmania, contact the Threatened Species Network Coordinator:
Telephone: (03) 6234 3552
You can also find out more information about Australia's threatened species by calling the Department of the Environment and Heritage Community Information Unit on free call 1800 803 772 or by visiting www.environment.gov.au/biodiversity/threatened.