Background
Southern Pygmy Perch (Nannoperca australis) are a small-bodied native fish endemic to south-eastern Australia. Once widespread and abundant throughout the Murray Darling Basin, the species has suffered dramatic declines in distribution and abundance, particularly since the 1970s.
While the species are regarded as common in coastal areas, the form found north of the Great Dividing Range is now present only in small, fragmented populations, with many regionally threatened. At the end of the Millennium drought, only 12 naturally occurring populations within four river systems were known to exist in Northern Victoria.
Habitat
As they are a native wetland specialist fish, Southern Pygmy Perch prefer to inhabit still or slow-flowing waters in streams, lakes and wetlands, but can also be found in backwaters of larger creeks and rivers. Dense aquatic vegetation and healthy fringing macrophytes are critical to their survival. Instream timber may also be an important habitat component. These habitats provide refuge and food for all their life-history stages.
In rivers and streams that periodically dry up, Southern Pygmy Perch can survive in shallow pools for extended periods, tolerating a broad range of water temperatures, salinities and extremely low dissolved oxygen levels.
Ecology
Southern Pygmy Perch (SPP) are short-lived, with a lifespan of one to three years in the wild or up to five years in captivity. 90% of ‘wild’ populations comprise of 1-2-year-old fish. These perch-like fish can grow to 95 mm in length and are carnivorous, preying on micro-crustaceans and aquatic insects. SPP are predominantly benthic, meaning they are bottom dwelling.
Breeding
Spawning typically occurs between September to January, triggered by rising water temperatures (15-18oC) and changing water levels or flow pulses. Spawning often occurs in slow-flowing or still waters with complex physical habitat and an abundance of aquatic vegetation. SPP breed in their first year (up to 45mm TL) and females can produce 50 – 4 000 eggs over aquatic vegetation, woody debris, rocks and the bottom of waterbodies.
Threats
As with many small bodied native fish, Southern Pygmy Perch are threatened by the impacts of river regulation and altered flooding patterns, clearing of vegetation along waterways, stock access leading to poor water quality and degradation of aquatic vegetation and predation from alien fish including Redfin, Trout and Eastern Gambusia (also known as Mosquito Fish).
The feeding habits of Common Carp (Cyprinus carpio) also directly damage aquatic vegetation on the bed of the waterbody and result in turbid water, which in turn limits light and subsequently the growth of aquatic vegetation that is so important to this fish.
Status
Southern Pygmy Perch is listed as Vulnerable on the Advisory List of Threatened Vertebrate Fauna in
Victoria (2013). Small population numbers, highly fragmented populations, short-life span and their limited dispersal capacity, has resulted in the onset of conservation actions to prevent their local and regional extinction.
With impacts from climate change expected to increase over the coming decades and stream flows predicted to decline by up to 30% in our region, the plight of the Southern Pygmy Perch is now stronger than ever.
Translocations to Farm Dams
The ‘Fish in Supplementary Habitats (FISH)’ program was established in 2018 to conserve threatened Southern Pygmy Perch. The aim of the project was to reduce their risk from extinction by establishing refuge populations in four private farm dams.
Establishment of refuge populations can reduce the potential and immediate threat from catastrophic state-wide loss, such as that suffered in a bushfire or extended drought, and also provide source populations for further translocations in the future.
Two of the four dams stocked in 2018 have become successful refuge and breeding sites for the Southern Pygmy Perch in the North East Victoria region. Since then, the Arthur Rylah Institute harvested source populations and translocated fish to 17 additional refuge sites in the Greta Valley catchment, bringing the total number of sites to 21. Initially the program was conservative, focusing on establishing more secure refuges above the 1 in 100 year flood line. Since 2022, the program has expanded to include farm dams that are connected during flooding or will overflow into neighbouring creeks or rivers periodically, to allow for a natural translocation into our local river systems.
An opportunity also arose early during 2023 to become the custodians and care for a rescued population of Southern Purple Spotted Gudgeon (SPSG) from North West Victoria. These fish were rescued from a lake during the flooding near Mildura in winter 2022 and cared for at Snobbs Creek Hatchery until a suitable translocation site could be found in our local area. The Group put a call out to landholders in the King catchment for suitable farm dam sites for these fish. Five sites were then assessed for their suitability as secure sites for the SPSG. The site with the most secure hydrological conditions and best instream habitat was the site at Hansonville and the SPSG were translocated to this site in March 2023.
How do we choose suitable sites for this species?
The habitat conditions that are most important when selecting appropriate translocation sites are the cover and diversity of submerged and emergent vegetation, stable water levels, restricted stock access, absence of predatory fish, shading and the landholder’s conservation ethos for the site.
SPP show a preference for habitats with slow flowing or still water, abundant macrophytes (shelter, food and spawning sites), high water security and sites that are devoid of predators and competitors. There habitat preferences make them a suitable candidate for translocation to farm dams.
The future of Southern Pygmy Perch
The successful translocation, survival and recruitment of Southern Pygmy Perch into selected private dams provides water managers and conservationists with a successful strategy to protect similar threatened small-bodied native fish in the future.
The Greta Valley Landcare Group will continue to work with the Arthur Rylah Institute to support the monitoring and further preservation of this species in sites across North East Victoria.
At the end of 2023, SPP had survived in 16 of the 21 translocation dams. In the last 6 years, we started with 1,000 fish, we now have > 5,000 fish and 9 self-sustaining populations, doubling the known number of SPP populations, thereby decreasing the species’ extinction risk.
Resources
You can read more about this project on the Southern Pygmy Perch in Farms Dams Factsheet. For more technical information consult the Final Report (2018) or the Supplementary Report (2019).
The Tri State Alliance for Small Bodied Native Fish Recovery also has also compiled some fantastic resources in this space:
Webinar
Dr Scott Raymond from the Arthur Rylah Institute took us through a great presentation outlining more about the translocation program and the habitat needs, breeding ecology, and threats to the survival of the Southern Pygmy Perch.
Video runs for 38 minutes. Recorded 19 November 2021.
Farm Dams
Please click on the green link below under ‘Site Details’ to read more about the habitat, water supply and translocations for each farm dam site.
| Landholder | Location | Fish Translocated | Success | Site Details |
| Gearon/Ott Dam 1 | Moyhu | SPP 17/05/2018 | Yes | Gearon 1 |
| Gearon/Ott Dam 2 | Moyhu | SPP 17/05/2018 | Yes | Gearon 2 |
| Gearon/Ott Dam 3 | Moyhu | SPSG 22/03/2023 | Too early to say | Gearon 3 |
| Mike Burtson | Myrrhee | SPP 17/05/2018 | Yes | Burston |
| Steve & Marie Whipps | Glenrowan West | SPP 16/05/2018 | No | Whipps |
| Brent & Pauline Bailey | Glenrowan West | SPP 16/05/2018 | No | Bailey |
| Peter Shanley Dam 1 | Moyhu | SPP 30/04/2021 | Yes | Shanley 1 |
| Peter Shanley Dam 2 | Moyhu | SPP 11/10/2022 | Yes | Shanley 2 |
| Peter Shanley (creek) | Moyhu | SPP early 2023 | Too early to say | Shanley 3 |
| Fiona McCallum | Greta West | SPP 15/09/2021 | Yes | McCallum |
| Bill & Val McMonigle | Glenrowan | SPP 15/09/2021 | Yes | McMonigle |
| Anthony Griffiths | Greta West | SPP 15/09/2021 | Yes | Griffiths |
| Marc & Sharon Sealey | Greta West | SPP 15/09/2021 | Yes & No | Sealey |
| Berry Dam A | Greta West | SPP 16/09/2021 | No | Berry A |
| Berry Dam B | Greta West | SPP 16/09/2021 | No | Berry B |
| Andrew Briggs | Glenrowan | SPP 12/10/2022 | Yes & No | Briggs |
| Arthur Parker | Oxley | SPP 16/09/2021 | Yes & No | Parker |
| Fosters Lake | Glenrowan | SPP 16/09/2021 | Yes | Fosters |
| Megan Callus | Greta South | SPP 11/10/2022 | Yes | Callus |
| Craig Stevenson | Lurg | SPP 12/10/2022 | Yes | Stevenson |
| Kylie Topal | Cheshunt | SPP 11/10/2022 | Yes | Topal |
Landholder involvement
The Greta Valley Landcare Group has been thrilled to work with ARI on this project over the past six years. We’ve included some photos below that characterise the spirit and enthusiasm that our landholders have bought to the project – with huge thanks to Dr Scott Raymond for his time and involvement over the years and for choosing us to partner with!
Completed projects
Please click on the links below to find out more about individual funding and project outcomes:
Southern Pygmy Perch in Farm Dams (2018-2019)
Establishing a refuge population of threatened Southern Pygmy Perch (2019-2021)
Southern Pygmy Perch in Farm Dams (2020-2021)
Introducing wild populations of Southern Pygmy Perch (2022-2023)
What are the barriers/challenges to implementation?
We believe that the biggest challenge to using farm dams to secure threatened populations of small bodied native fish is due to natural weather conditions and the regularly changing hydrologic conditions in each of the farm dam sites. Depending on their location in the catchment, we have sites that range from spring fed (secure), through to those located on the floodplain of a major river (risky). The level of risk we are prepared to accept depends on: total number of translocation sites for each species; how many secure sites we have and their breeding capacity; how many fish we are prepared to lose to the local river system during flood events (natural seeding of populations); cost associated with monitoring and translocation of additional fish to top-up existing sites.
Recent follow up monitoring of sites from 2021 revealed that Weatherloach had moved into one dam (aquarium species), floods had mostly swept SPP from two sites and another excellent site had been overtaken by algae. All four of these sites were, what we thought upon initial translocations, A-list sites where our fish would breed prolifically! And yet we had been thrown a curve ball. Without monitoring we would have had no idea of the trajectory these sites were on. Follow up monitoring also allows us to make assessments of the health of the remaining population, whether active intervention is required to change the conditions or whether top-up translocations were required at the site.
Take home messages
- Translocations are a valuable tool for threatened species conservation
- We need to follow (and develop) an established translocation process
- Farm dams as ‘interim’ surrogate habitats have been a huge success
- Landholders and the local community are the key to project success.
Funding Sources
