Finding invisible fish: the power of eDNA
What if we could discover which fish live in our waterways without having to catch or even see them? That's the promise of environmental DNA (eDNA) — a rapidly emerging monitoring method helping scientists and communities better understand the fish living in our rivers, wetlands and coastal habitats.
What is eDNA?
All living things leave behind tiny traces of genetic material, or DNA, in their environment. Fish release skin cells, mucus, faeces and urine into the water, all of which contain DNA .
By collecting water samples and analysing the DNA they contain, scientists can identify which fish species are present in a waterway — like analysing evidence from a crime scene.
Why is eDNA a big deal for fish monitoring?
Traditional fish surveys often rely on underwater cameras or physically catching fish to identify species. These methods can be time-consuming, invasive and difficult to use in some environments — especially in a region where crocs make estuarine fish collection an additional chompy challenge.
eDNA analysis offers a promising alternative. A simple water sample can provide valuable information about fish biodiversity, helping scientists detect species that might otherwise go unnoticed.
It could also help us better understand the distribution of native fish and detect invasive species, such as tilapia, that threaten the health of our waterways.
“Importantly, eDNA also opens up opportunities for citizen scientists to contribute to monitoring and protecting their local waterways,” says Executive Officer Kara-Mae Maguire. “And the value of this could be exponential — the more volunteers involved, the more we stand to learn.”
“eDNA opens up opportunities for citizen scientists to contribute to monitoring and protecting their local waterways.”
How is eDNA being used around Townsville and the Dry Tropics?
While eDNA is already being used across the Great Barrier Reef to tackle crown-of-thorns starfish, a new citizen science project, eDNA Fish Monitoring for Reef Waterways, is bringing this promising technology to waterways across the Lower Herbert, Townsville and Lower Burdekin regions.
The project is developing a community-based approach to collecting water samples and monitoring freshwater and estuarine fish biodiversity. By working with local volunteers, it aims to make fish monitoring more accessible while building a clearer picture of native and invasive fish species across connected rivers, wetlands and coastal habitats.
The Healthy Waters Partnership for the Dry Tropics is contributing technical oversight to explore how eDNA data could be incorporated into our Waterways Report Card.
“The new eDNA monitoring has the potential to fill important information gaps by providing data at a finer, sub-basin scale than previously possible,” Maguire explains. “It could give us valuable insights into waterways where data has previously been limited, helping us build a more complete picture of fish populations and ecosystem health across our region.”
The latest project is made possible through funding from the Australian Government Department of Climate Change, Energy, the Environment and Water, through the Great Barrier Reef Citizen Science Program. The project is supported by the Healthy Waters Partnership for the Dry Tropics, OzFish Unlimited, JCU TropWATER, CSIRO, the Great Barrier Reef Foundation, Bioplatforms Australia, and community partners.
How you can get involved
OzFish is inviting Dry Tropics community members, fishers, waterway users and local custodians to get involved in eDNA sampling and other citizen science activities, including collecting water samples from local waterways.
Whether you're keen to participate in a sampling event or simply follow the project's progress, there are opportunities to contribute.
