Project key points
- The Victorian Fisheries Authority (VFA) has been funded by the Australian Government Murray–Darling Water and Environment Research Program (MD-WERP) to work with Traditional Owners and other partners along the Victorian Murray Corridor to identify and utilise three natural wetland ecosystems as “nursery areas” for stocking native golden and silver perch.
- This 12-month pilot project builds on a previous informal pilot study in Wallpolla – Horseshoe Lagoon. Additionally, other recent studies e.g. by Iain Ellis (see “Managing Wetlands for Native Fish”, Finterest, February 2025) strongly support this concept.
- This project revolves around close partnerships with the First People of the Millewa Mallee Aboriginal Corporation, Barapa Barapa Traditional Owners, Mallee and North Central Catchment Management Authorities (CMA’s), the Victorian Environmental Water Holder (VEWH) and the Arthur Rylah Institute.
- Following the identification of suitable sites, wetlands were filled with water for the environment, monitored for zooplankton (prey for larval fish) and then stocked by the VFA with larvae and fingerling golden and silver perch.
- The project is underpinned by a detailed monitoring and harvest strategy to capture fish and translocate them to permanent waterways.
- At the end of the project wetlands will then be allowed to reset according to their individual wetting and drying regime.
Project scope
1. Explore an innovative stocking strategy (proof of concept) for golden and silver perch. Key questions:
- Can wetlands, where water for the environment is mimicking natural wetting and drying cycles, also be potential nursery environments for native fish?
- Will wetland productivity levels deliver rapid, sustained growth of juvenile fish?
- Can we effectively harvest the fish from the wetlands for translocation to permanent waterways?
2. Work closely with Traditional Owners on Country to develop two-way knowledge sharing between First Nations science and knowledge and western fish ecology/water management sciences. In particular:
- Monitoring wetland and fish stocking performance,
- Aquaculture/stocking practices
- Water quality
- Harvest and translocation of fish from the wetlands into selected permanent waterways.
This project, and the lessons learned from it, could provide the basis for a new native fish recovery tool to enhance our fish stocking program with strong First Nations/Traditional Owner community involvement. It may also demonstrate how the ecological requirements of native fish larvae and fingerlings can be considered in environmental watering plans when complimentary to other outcomes for native plants and animals.
Community participation in these projects can also provide additional benefits from a First Nations perspective through maintaining cultural knowledge and supporting generational transfer of knowledge, and ensuring cultural practices are maintained.
Background
As a consequence of extensive river regulation, the natural wetting and drying cycles of floodplain wetlands has been greatly altered, with most wetland complexes now essentially disconnected from the life blood of the Murray River. This has had a huge impact on these natural ecosystems, and the plant and animal species they support.
The majestic River Redgum is frequently portrayed as the flagship species for the recovery of these ecosystems. However, what is often less well understood is the central role that floodplain wetlands have for native fish, and not just for small bodied (yet no less significant!) native fish. Even large bodied native fish are small at some point, and these systems are critical for the recruitment of two of our most iconic native fish: golden and silver perch.
These two “floodplain specialists” rely on wetlands as a fundamental part of their recruitment strategy. Before river regulation, natural flooding would stimulate native fish spawning in the river during spring & early summer. Eggs and/or larvae are then washed into adjoining wetlands, where the juvenile fish can reap the benefits of these incredibly fertile, warm, sheltered “nursery” environments. Subsequent floods over the next 1-2 years would then create the opportunity for grown fish to return to the river, whilst repeating the cycle as new larvae are washed into the wetland. The loss of wetland connectivity has dramatically reduced opportunities for ephemeral wetland nurseries to regularly boost recruitment in this way. To add to the insult, pest carp now invade wetlands that do fill during floods and disrupt aquatic plant germination (baby fish habitat), devour resources necessary to developing native fish, and impact water quality via their burrowing feeding activity.
With such limited access to these nursery environments (alongside other threatening processes), golden and silver perch are now respectively listed as a “threatened riverine community in the Southern Murray Darling Basin”, Flora and Fauna Guarantee Act and “critically endangered”, EPBC Act.
To help their recovery the VFA already stocks both species as part of our annual fish stocking plan. However, these hatchery reared fingerlings (<40mm) miss out on an extended growth period and are stocked directly into flowing waterways. Unfortunately, it is not possible to hold these fish for longer periods in the hatchery, so developing a means to grow fingerlings to a more robust size of 150mm+ fish, could herald a more rapid recovery of wild populations and increase a return on captive breeding programs.
Site selection
Criteria for site selection was developed at the outset of the project, initially using a rapid “First Pass Wetland Assessment” tool developed by the VFA that was distributed amongst Environmental Water Officer networks along the Murray Corridor. Prospective wetlands were ranked against a number of key criteria, importantly: Is the wetland already part of an approved seasonal watering proposal to receive water for the environment within the project timeframe?
From an initial 33 scoped wetlands, the list was then passed through a facilitated workshop exercise at the “Wetland Warriors” forum hosted by the Tri-State Murray NRM Regional Alliance and North Central CMA at the Winton Wetlands Knowledge Hub. This reduced the list down to five, which were then ground-truthed on Country with Traditional Owners and CMA staff.
Three sites were selected that perfectly fitted all the criteria, with one extra “wildcard” site. Musk Duck Lagoon, Ducksfoot Lagoon and Yarran Creek were the primary sites, with Karadoc-Outlet Creek serving as the back-up. As it happened, when it came time to water the sites one of the preferred locations was unsuitable as it still held too much residual water due to an unexpected rain event, plus a residual carp population, and so the “wild card” site was pressed into service!
Stocking
Musk Duck and Karadoc-Outlet Creek were supplied with an allocation of water for the environment over December 2024 – January 2025. Following a 9-day period of monitoring to ensure plankton growth was suitable to sustain larval stage fish, the wetlands were stocked. In total, Karadoc-Outlet Creek received 84,000 silver perch and 200,000 golden perch, and Musk Duck received 200,000 silver perch and 20,000 golden perch.
The third wetland, Yarran Creek, is a totally different system, being an ephemeral creek in the Gunbower Forest. Due to the need to align the timing of watering with the ecological requirements of the site, Yarran Creek was not watered until late March 2025 and then stocked with fish in mid-April. The later watering timeframe provided us with the opportunity to trial stocking fingerlings instead of larvae to give them ahead start. Consideration also had to be given to the fact that it was getting late in the year for larvae production in the hatchery.
Early signs of success!
In March 2025 the Arthur Rylah Institute undertook the first post-stocking surveys at the Musk Duck and Karadoc-Outlet Creek wetlands. The astonishing productivity of these systems was clear to see, with thousands of yabbies and shrimp caught in overnight sets of fyke nets, alongside copious amounts of plankton, macroinvertebrates, tadpoles and turtles.
Most exciting of course, was the detection of both silver and golden perch juveniles in amazing condition. Both had reached lengths of over 100mm in just a couple of months! Given the quantity of larger prey items in the wetlands, as soon as they are able to consume larger organisms we can expect these growth rates to continue to head off the chart!
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