The Murray–Darling Basin is the largest and most complex river system in Australia. It spans from Queensland, through New South Wales and the Australian Capital Territory, Victoria and South Australia, covering 77,000 kilometres of rivers, many of which are connected. The Basin contains over 30,000 natural wetlands along with their associated biota of plants, invertebrates, fish, waterbirds and other vertebrates. Despite having been greatly modified from their natural state, these habitats and environments retain significant cultural, scientific, conservation, ecological, recreational, and commercial values. The 23 river valleys and more than 30,000 wetlands of the Basin are home to over 60 species of native fish. Most of these species are unique to Australia, with a number living only in the Basin. View some of these native fish species here.

Native fish in the Murray-Darling Basin have declined to just 10% of their pre-European settlement levels. Habitat loss, waterway degradation, intense bushfires, and large-scale fish death events, such as those in the lower Darling River in 2018–2019, have worsened the crisis. Many native species are now restricted to small, fragmented populations, leaving them vulnerable to extinction.

The Native Fish Recovery Strategy put together by the Australian Government, aims to reverse this trend over the next 30 years. The Fish Friendly Water Extraction Project is an integral part of this strategy, which aims to protect and recover native fish populations. It has been developed and will be implemented collaboratively with Basin states, First Nations peoples, aquatic ecology experts and communities along the Basin’s rivers and wetlands. In the first decade, the focus will be on:

• Recovering and sustaining native fish populations
• Mitigating threats to fish habitats and ecosystems
• Involving communities in conservation efforts
• Using science and knowledge to guide recovery actions
  

Scientific studies in Australia have provided some of the best data globally on native fish losses at water diversions or extractions, such as irrigation pumping. These insights highlight the significant impact water extraction has on native fish populations.

Key Findings from Research

1. Pump Diversions on the Namoi River (Baumgartner et al., 2007, 2009):

• Two pump stations (with capacities of 35ML/day and 150ML/day) were studied.
• Sampling revealed that 232 fish per day were removed, 70% of which were native species.
• On average, one native fish was lost per megalitre of water diverted.

2. Experimental Pump Studies (Boys et al., 2012, 2013):

• Research on both an experimental pump (35ML/day) and a regulated pump on the Namoi River found higher losses.
• Approximately 3.5 native fish were lost per megalitre of water diverted.

3. Oakey Creek Study (Brown et al., 2015):

• A 300mm intake pipe in Queensland’s unregulated Oakey Creek system removed more than 9,000 Australian smelt in a single afternoon.

4. Harrah Lakes Study (Brown et al., 2015):

• Severe injuries were documented in 75% of fish passing through pumps, including de-scaling, decapitation, and eye injuries (exophthalmia).

Even conservative estimates suggest that irrigation has had a massive impact on the sustainability of native fish populations. In nearly all studies, diversion from natural waterways is effectively a one-way trip for fish, permanently removing them from breeding cycles. This leads to long-term declines in population numbers and threatens the ecological balance of aquatic ecosystems.

A Call to Action

The Native Fish Recovery Strategy relies on partnerships with First Nations peoples, recreational fishers, conservation groups, industry, and local communities. Together, we can protect these unique species, restore balance to our waterways, and ensure future generations inherit thriving rivers and wetlands. Let’s work towards healthy fish, healthy rivers, and healthy communities.

“Without urgent intervention through a major program such as the Native Fish Recovery Strategy, we could see the extinction of native fish species (… found nowhere else on Earth) from the Murray–Darling Basin over coming years.”

Dr Paul Sinclair, Campaign Director, Australian Conservation Foundation.