Native Fish Face Growing Extinction Threat

Freshwater ecosystems are facing growing pressure from climate change, invasive species, declining water quality and habitat degradation, with researchers warning some native fish species are at risk of extinction. Photo source: Queensland.com

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Australia’s freshwater fish are facing an escalating extinction threat, with new research highlighting the growing pressure on waterways from invasive species, climate change and declining water quality.

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Researchers from James Cook University and Griffith University assessed 22 rare and threatened Australian freshwater fish species, drawing on published research and the knowledge of regional aquatic specialists.

The study found invasive species, habitat degradation, altered river flows and climate change were among the most significant threats to native fish populations, while crossbreeding between introduced and native species was also identified as a concern.

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James Cook University Principal Research Officer Dr Aaron Davis, a co-author of the study, said freshwater ecosystems were experiencing significant biodiversity loss.

"Modern extinction rates for freshwater fish are more than 100 times higher than natural extinction rates. Globally, nearly one-third of freshwater fish species are at risk of extinction, while an estimated 37% of Australian freshwater fish species are threatened," Dr Davis said.

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Rainbowfish and cling gobies were among the species identified as facing the greatest risk, with several classified as being at high or very high risk of extinction.

Dr Davis said some species were particularly vulnerable because their entire populations could be confined to small catchments.

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“So, their entire global population is extremely vulnerable to a range of potential catastrophic events like pollution, a major landslide upstream filling up instream habitats, a heatwave or hypoxic (low dissolved oxygen) event, or the introduction of a feral species, affecting the entire population. An event like this, which can be very local, and certainly do occur, can wipe out an entire species.”

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The researchers are calling for stronger protection and restoration of critical habitat, improved riparian vegetation management, invasive species control, and targeted translocation and captive breeding programs.

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"If we don't move quickly, we risk losing species found nowhere else on Earth," Dr Davis said.

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