Baby Barramundi Booming In Restored Wetlands 

Recent monitoring of restored wetlands at Alligator Creek near Mackay has shown thriving populations of native fish communities, including juvenile barramundi. This success follows comprehensive restoration efforts, which have transformed the once shallow, weed-infested wetlands into vibrant ecosystems.

The restoration works have included improving fish passage through the implementation of rock fish ladders, constructing deep pool refuge habitats, revegetation, and improved grazing management. Before these efforts, the wetlands were often dry and overrun by hymenachne, an invasive aquatic weed that reduces dissolved oxygen to levels unsustainable for aquatic life.
The restoration project was designed by Matt Moore, Fisheries Ecologist at Catchment Solutions, with funding from Reef Catchments NRM via the Australian Federal Government Reef Trust.  
“When people think about water quality, they often think about nutrients and pesticides and forget about oxygen. However, many coastal wetlands in North Queensland don’t have enough oxygen to sustain aquatic life. This is a major issue that has largely been forgotten about.'"
The work included creating deep pool refuge habitats and adding large hardwood logs to increase habitat complexity.
Moore explained, "The deep pools help manage invasive weed problems, as these prefer shallow areas. The refuge pools with logs provide cooler temperatures during the summer and help baby barramundi survive the dry season before migrating back to saltwater habitats to breed.
“Improving connectivity and ensuring good water quality means we have healthier populations of iconic barramundi. These are important to coastal Queensland communities, sustaining recreational, commercial, and Indigenous fisheries and playing a vital role in aquatic ecosystems as top-order predators, including helping the fight against pest fish populations."
Reef Catchments Senior Project Officer Carlos Bueno explained how important wetland restoration is to the fish breeding cycle.
"Barramundi breed in saltwater before their juvenile offspring undertake a lifecycle-dependent migration into freshwater wetlands at approximately 50 mm in length.
“At this small size, they are weak swimmers, so fish barriers like weirs, road causeways, and pipe and box culverts often block this critical migration, reducing barramundi populations and impacting aquatic ecosystem health. Remediating barriers with rock fish ladders allow baby barramundi to reach wetlands, which they use as nursery habitats for the first few years of their life before migrating back to saltwater to breed."
The wetland restoration works have been a collaborative effort with local grazier and sugar cane farmer Paul Bradford, demonstrating that improving wetland health and barramundi populations can go hand in hand with farming.
MrBradford commented, "This project shows that sustainable farming and wetland conservation can coexist and benefit each other."
This successful restoration project at Alligator Creek is a testament to the effectiveness of targeted ecological interventions and highlights the critical role of improving farm management practices to enhance water quality runoff. (e.g. fencing and off-stream watering points).
By adopting better farm management techniques, significant reduction of pollutants (fine sediments, nutrient and pesticides) entering waterways can be achieved, thereby supporting healthier wetland ecosystems. Such efforts not only benefit wildlife but also contribute to the well-being of local communities who rely on the ecosystem services provided.

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Matt Moore holding juvenile barramundi (young of the year) recorded during electrofishing surveys at the wetlands. The baby barramundi use the restored wetlands as nursery habitats for the first few years of their life before migrating back to saltwater

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Before and after; showing some of the restored wetlands. Photos supplied

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Juvenile barramundi and tarpon on the measuring board sampled via electrofishing monitoring in the wetlands

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