A genetic rescue operation

They say visionaries look through the lens of the future in order to see possibilities, the potential to realise a distant dream.

Perhaps that’s what drove the clever individuals who, 100 years ago, took the extraordinary step of translocating thousands of native fish from the Murrumbidgee River to the Cataract Dam near Wollongong.  In doing so they may have helped save the Macquarie Perch—known affectionately as Maccas.

Access to fresh water was vital for European colonisers to prosper in such a dry foreign landscape. Homesteads were established on the banks of meandering rivers, villages soon grew, then towns flourished. Unfortunately, this incremental development had a detrimental impact.

Of all our ecosystems, our rivers have borne the brunt. Our continent’s arteries are no longer pulsating with raw energy, no longer brimful of fresh water aquatic life. Clogged with sediment and starved of flow, our rivers are impacted by weeds, polluted by our urban runoff. When you add water extraction, disease, introduced fish species, overfishing and barriers to migration, the result has been the devastating decline of native fish species; today it’s estimated to be just 10% of pre-European levels.

The magnificent Maccas have suffered, becoming one of the most endangered species in the Murray–Darling Basin. Populations have declined, become isolated and genetically compromised. The hereditary traits that ensure their long-term survival as a species, such as their adaptability to climate change, is likely to be in grave jeopardy.

Our own Cotter River population hasn’t been exempt. Despite being protected and managed for these threats, recent genetic research has revealed our Maccas are genetically impoverished.

But the good news is that back in 1916 our erstwhile visionaries decided to ‘Harvest Nature’s Waste’ by translocating native fish from billabongs and weirs before they dried up. Thousands of Maccas, Murray Cod, Trout Cod, Silver Perch and Catfish were moved to Cataract Dam.  For just over a century the Maccas prospered within the dam’s tranquil waters, breeding in Sydney’s water supply—a large, genetically diverse population quietly going about their business, unaware of the plight of their kin in the Murray–Darling Basin.

Scientists are now reaping the benefits of that historic translocation. A genetic rescue operation is underway through a collaboration between the ACT Government, the University of Canberra and Monash University—funded through an Australian Research Council initiative.

A select group of Maccas have made a triumphant return to their ancestral home within the majestic Cotter River. These genetically vigorous young Maccas, which are the same strain as the Cotter River population, carry the inherent destiny of a species thanks to the foresight of those whose footsteps we walk in today.

Brett Mac

Brett McNamara - Regional Manager with ACT Parks & Conservation Service

Brett loves our national parks almost as much as the Gang-gang on his uniform. He is prone to using the word 'majestic' when referring to the bush capital. He loves talking. A lot. His favourite animal is the playful Platypus.

Article also appeared in The Chronicle