Helping fish thrive through the wet and the dry

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Author: Dr Matthew Coleman, MDBA General Manager Science and Evaluation

This year, helping to sustain native fish populations will be a priority for water planners and environmental water holders.

The Murray–Darling Basin Authority (MDBA) has released its recommendations on how water for the environment should be used so that it best meets the needs of native fish, waterbirds and plant life—something we’re required to do under the Murray–Darling Basin Plan.

The Basin Plan sets out to achieve a sustainable environment across the one million square kilometres of the Basin—not just at the individual catchment level. It’s also looking to secure a sustainable future for communities and industries in the Basin.

Gunbower Creek near Cohuna

In the past few seasons there has been significant fish breeding in parts of the river system, especially the Darling, the Murray and the Murrumbidgee rivers. These fish are maturing and will need to be able to move up and down the rivers to find new food sources and opportunities to produce the next generation of fish. As a result, we are placing a priority on sustaining those populations and their ability to migrate.

Where conditions have been dry in the northern catchments for some time, we recommend maintaining river flows at least at a low level so fish, and the invertebrates they rely on for food, have somewhere to live.

This will build on the benefits of a recent 23-gigalitres environmental flow that successfully delivered water from the Border and Gwydir rivers in the north to the Barwon–Darling and on to the Menindee Lakes. We will continue to witness the benefits of this flow to fish and their habitats over the coming months as plants, insects and other river life get a boost along the 2000 kilometres of river networks that received a welcome drink.

If dry conditions continue in the north, we anticipate more events like this may be needed to ensure fish populations, especially Murray cod and golden perch, are maintained until the next wet period.

In the southern system we expect to see more moderate conditions, which means water will be available for water managers to assist the species that have grown in the past few years.

Making sure rivers connect with each other and with the floodplains and wetlands is also critically important to enable young fish to migrate up and down the river system. This connectivity is essential for moving food and nutrients from the floodplains to the rivers. We saw successful watering by Commonwealth, state and local authorities in the Campaspe and Goulburn Rivers recently, with silver perch and even lamprey moving throughout the Murray River and its tributaries.

This thoughtful management of water adds up to plenty of fish that are just entering the juvenile to adult stage across the Basin. If you are casting a line into your local river, you can expect to see more fish moving through the system in the coming years, thanks to carefully delivered flows at the right time, in the right volumes to support the environment.

You can find out more about the 2018-19 Environmental Watering Priorities in the Murray–Darling Basin on the MDBA website here.

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