Hardie, S, Australian endangered species: Tasmanian galaxiids, The Conversation, Australia, 23 January 2014 (2014) [Magazine Article]
Official URL: http://theconversation.com/australian-endangered-s...
While the rivers of northern Australia and the Murray-Darling Basin are renowned for their iconic, large-sized, fish species such as Murray Cod and Barramundi, the temperate inland waterways of Tasmania are home to numerous "minnow-type" fishes.
Many of these species belong to the family Galaxiidae. In fact, the island state is a hot-spot for "galaxiid" diversity with 16 species (including 11 endemics). Galaxiids dominate the freshwater fish fauna of Tasmania (making up 64% of native fish species). While they donít provide much sport for anglers, they are important components of its iconic freshwater ecosystems. These include glacial lakes such as Lake St Clair, the deepest lake in Australia, and the wild west coast rivers such as the Franklin.
The life cycle and habitats of galaxiid fishes vary, with both migratory "diadromous" and non-migratory species. Some species use either strategy depending where they live. In Tasmania, migratory species typically inhabit streams as adults and move to the lower reaches of rivers and estuaries to breed in late autumn. They scatter a few thousand eggs over aquatic vegetation or rocks in the shallows. Their larvae grow in estuarine and near-shore marine areas and migrate back into freshwater as schools of juveniles, known as whitebait.
Non-migratory species complete their life cycles in lakes and lagoons, and typically produce fewer eggs (hundreds not thousands). Like overly-protective parents, non-migratory Paragalaxias species carefully attach adhesive eggs to the undersides of rocks along lake shorelines and guard them for up to a month until they hatch. The larvae of some non-migratory species live in open water until they are big enough to require refuge from predators, after which they seek shelter amongst rocks and aquatic plants.
While some Tasmanian galaxiids can live for up to 10 years, most live to less than three years. All endemic galaxiids to Tasmania have limited distributions. This along with habitat alterations and their relatively low fecundity, short life-span, small-size and inability to coexist with introduced fish has led to the demise of several species.
|Item Type:||Magazine Article|
|Keywords:||freshwater ecosystems, threatened species, freshwater fish, conservation, biodiversity, lake|
|Research Division:||Biological Sciences|
|Research Field:||Freshwater Ecology|
|Objective Group:||Flora, Fauna and Biodiversity|
|Objective Field:||Fresh, Ground and Surface Water Flora, Fauna and Biodiversity|
|Author:||Hardie, S (Dr Scott Hardie)|
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