Swan Galaxias (Galaxias fontanus)

Swan Galaxias (Galaxias fontanus)

Image of adult fish and map of known distribution (DPIPWE 2008) from records in 2008 ('recent') and 1980-2000 ('historical').

The recent distribution shown here is believed to be fairly accurate, though there may still be one or two small populations as yet undiscovered.

The true historical distribution, prior to introduction of trout and redfin perch, is believed to have extended throughout the Macquarie catchment drainage system.

Copyright Deborah Williamson. Please contact us for any dealings with this work

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Animal

Native

River: Channel

The Swan River Galaxias is a native fish of the family Galaxiidae – a group of native southern hemisphere fish occurring in southern Australia, New Zealand and Chile – which is especially diverse in Tasmania. The species was first discovered in the upper headwaters of the Swan River on the east coast. Further surveys over the last thirty years have revealed small isolated populations in eastern tributary creeks of the upper Macquarie River catchment, as well as five small western populations in creeks draining Macquarie Tier and the lower slopes of the Western Tiers between the catchments of Dairy Creek and Floods Creek.
This species swims in shoals in permanent pools in small woodland or forested streams with good cover (logs and rocks) where it lays sticky eggs on the underside of rock and wood surfaces.
All known natural populations are found upstream of a natural barrier to upstream fish movement – waterfalls, chutes or poorly defined wetland drainages. This, along with the known disappearance of two populations once trout and redfin perch became established in their habitat indicates that the species is highly vulnerable to predation by those two introduced fish species. It also suggests that the Swan Galaxias was widespread and locally abundant throughout the Macquarie, and perhaps the South Esk, catchments prior to European settlement.
Swan Galaxias populations persist in small, shaded creeks in zones in which flow and pool habitats are sustained during the summer-autumn months by groundwater inflow – that is, typically below the elevation of contact between dolerite and older geologies, and above barriers to introduced fish invasion.

Management should focus on protecting the remnant creek habitats from alterations to flow regime, erosion and water quality; from the clearance of riparian forest; and from any physical alteration to the downstream channel which might allow fish invasion. The causing of inflow by diversion of other streams should be avoided as well as the construction of new farm dams within their stream drainage (with the associated risk of future stocking with redfin perch or trout).
Several new populations have also been successfully established within the species’ former range by translocation into small previously fishless streams above suitable barriers.
All known populations are highly vulnerable to prolonged drying, since they occupy small stream systems. Management options to sustain the species consist of further translocations within and outside its range; translocation to protected permanent water bodies (storages/lakes); enhancement of existing stream refuge suitability by enlarging pool depths and lengths; and/or supplementation of flows and water supplies through controlled and screened diversions to sustain refuge habitats through prolonged dry periods.