Macquarie perch were once abundant in their namesake, the Macquarie River, yet are now extremely threatened throughout the Murray-Darling Basin. The species is considered extinct in SA and endangered in NSW, VIC and ACT. Extinction is looming for this little fish, with only four isolated wild populations left in NSW, spanning less than a combined total of 200km of stream.
A key threat to the Macquarie perch is introduced species invading habitat, causing erosion and affecting river water quality. The disruption to the environment has resulted in the smothering of spawning beds and refuge holes that Maccas rely on to reproduce. Given that female Macquarie perch take approximately 3 years to reach sexual maturation – this spells trouble for a rapidly declining species.
Researchers with DPI Fisheries collected a small group of Maccas from the remaining wild populations in the hopes of establishing an insurance population. The fish were kept at the Narrandera Fisheries Centre until a safe refuge site could be located to re-establish the iconic species.
The Winburndale Dam and the subsequent Winburndale Rivulet, provided an ideal location for the project. With the dam being restricted from public access, the site provided relief from the pressures of recreational fishing. The closed system is also located within the Macquarie catchment, making this site particularly historic.
There was only one issue with this site – the overwhelming abundance of Brown trout. In late 2021, recreational fishers were enlisted to aid in the removal of trout from the dam. The trout were relocated to Millponds at Portland to provide a substantial recreational population that is now accessible to the community, a win-win for native fish and rec fishers. In one month, approximately 1000 Brown trout were moved out of the system. This not only secured a safer habitat for the Maccas, but also brought the community together for the longevity of Macca perch and the establishment of sustainable recreational fishing in the area.
Fisheries staff have been back in recent weeks to monitor how the fish from previous releases are faring. The team used a combination of fyke nets and electrofishing to conduct their monitoring. The preliminary findings have produced exciting results, with results exceeding expectations. The fish are in great condition and the population is varied, showing diversity in size and age class.
Learn more about the return of the Maccas in this video from Ozfish:
Scientific progress for fish
In addition to these incredible on ground efforts, in 2021 the NSW DPI team worked with scientists from the University of the Sunshine Coast to establish a specific breeding hormone which targeted female Macquarie perch. The hormone accelerates the maturation process, reducing it from 3 years to somewhere between 36-48 hrs. The hormone breeding trials have been running for 3 years now, producing 3 successful spawns and showing extremely promising results.
The journey of Maccas has been a tumultuous one, but there is a glimmer of hope in these recent recovery activities. This work reminds us of the value of partnerships between scientists, communities and government in restoring our native fish.
Featured image: Macquarie Perch.
Photo credit: Tarmo A. Raadik