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Partnership protects endangered perch

A local land manager has combined forces with South East Local Land Services, Fisheries NSW and Greening Australia to construct two barriers to prevent the spread of exotic fish, and protect one of the last populations in NSW of the rare and endangered southern pygmy perch.

The Southern pygmy perch is a small fish, growing to approximately 65-85 mm in length. Once widely distributed throughout the Lachlan, Murrumbidgee and Murray River systems, it has suffered large-scale reductions in its range since European settlement

There are only three small isolated populations remaining in NSW, the threat of losing this species from the state is very real.

One of the major causes for the decline in southern pygmy perch is competition and predation from exotic species particularly carp and redfin.  The recent invasion of redfin into Urumwalla Creek has been decimating the population of southern pygmy perch within that system. The redfin have been moving up stream progressively wiping out the pygmy perch as they go.

With no real means of eliminating the redfin at this stage, a project was undertaken to identify any areas within the system that redfin had not reached, and then try to stop them invading these areas.

Techniques such as the use of environmental DNA, electrofishing and netting were employed to determine the extent of the redfin invasion and to identify any areas that they had not yet reached.  Of all the areas investigated only one small section of the upper Urumwalla Creek was identified.  It contained both a good number of southern pygmy perch, the habitat they require, and no redfin.

With funding and resources from South East Local Land Services and the Rivers of Carbon partnership of Greening Australia and the Australian River Restoration Centre over 175 tons of large rock was used to construct two barriers to prevent the movement of exotic fish including redfin upstream, and protect the southern pygmy perch that reside above the barrier.  The rock walls were designed and constructed by South East Local Land Services staff who specialise in this field.

The site where the barriers were constructed also had a pre-existing erosion head cut.
The construction of the structure will benefit the pygmy perch above it.

They will be protected from exotic fish and their habitat will be prevented from being undermined by erosion. The stabilisation of this erosion will also benefit the health of the system by reducing sediment input downstream.

While the population of pygmy perch above this barrier is safe for now from exotic fish, a broader project is currently being undertaken with Gunning District Landcare to try and identify locations safe from exotic fish where other populations of southern pygmy perch can be established.

Fisheries NSW will continue to monitor the site for the presence and population growth indicators of the southern pygmy perch, and any evidence of red fin and other threats.

Melissa Henry
Land Services Officer
Melissa.Henry@lls.nsw.gov.au

Sari Glover
Senior Land Services Officer, NRM
Sari.Glover@lls.nsw.gov.au