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Using eDNA to detect barriers to fish barriers in Australian waterways


  • Structures like culverts, weirs, causeways, and tidal gates are common barriers that prevent fish from migrating between freshwater and marine habitats, leading to a decline in fish diversity.

  • TropWATER scientists are using environmental DNA (eDNA) technology to understand the distribution of various fish species in northern Australia, identifying which structures act as barriers to fish migration.

  • This research is helps decision-makers determine how to manage these barriers, whether by removing them or implementing measures to facilitate fish migration.

Key points

Using eDNA to detect barriers to fish barriers in Australian waterways


Cecilia Villacorta-Rath

Senior Research Officer

Damien Burrows

Director, TropWATER Founder

Research leads

How fish barriers impact Australian native species

Human-made physical barriers like culverts, weirs, causeways and tidal gates are common fish barriers, stopping fish from migrating between freshwater and marine habitats. This loss of connectivity is contributing to a decline in fish diversity.

Many Australian fish species need to move between marine and freshwater habitats at different times of the year to feed, reproduce, spawn, access nursery grounds and escape predators.

Barramundi in particular struggle with barriers, limiting their ability access essential habitats. In extreme cases, barriers like large weirs and dams can lead to localised extinctions.

Thousands of barriers exist in coastal areas, making it critical to understand their effects on fish communities. Determining the fish communities that have been able to make it past these barriers is key to understanding their effects on Australian native fish.

How eDNA helps identify fish barriers in Australia

TropWATER scientists are using eDNA technology to revolutionise how we identify problematic fish barriers in Australian waterways.

The technology uses water samples to detect genetic material left in the water, such as mucus, scales, and other residues, without capturing or sighting the species. These methods help scientists quickly see if key fish, such as barramundi, can migrate past these barriers, and if it's harming fish diversity.

This is pinpointing which structures block fish passage for fish migration and survival, providing critical data to support better management. Detecting fish species upstream from such structures using eDNA methods could give an idea of whether these are impeding fish migration.

The impact of eDNA technology on fish barrier monitoring and management

With eDNA technology, managers can make informed decisions about barrier removal or modification, ensuring better connectivity for fish populations.

eDNA methods allow for more accurate environmental impact assessments by providing precise data on fish presence and migration patterns. This data helps organisations and environmental managers who need to identify problematic barriers and develop strategies to mitigate their impacts.

This approach not only enhances fish diversity but also supports the sustainability of freshwater and marine ecosystems in northern Australia.

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