Dept of Climate Change, Energy, Environment & Water
Fishways – More Than Just Passageway For Native Fish
Did you know fishways not only help native fish travel thousands of kilometres throughout the Murray-Darling Basin? They can also help with monitoring movement and managing invasive fish.
Most Australian native fish species need to move to complete their lifecycle. The environmental water that the Commonwealth Environmental Water Holder (CEWH) and other water holders provide in the Murray-Darling Basin, is crucial for fish movement and breeding.
Given the right conditions, some native fish can travel from hundreds to thousands of kilometres. However, weirs and dams, constructed to provide water for human use, can get in the way of our native fishes’ epic journeys.
To help adventurous native fish find a mate or healthier habitat, the CEWH is working to optimise fishways for native fish with:
Dr Ivor Stuart is a freshwater fisheries researcher from Charles Sturt University. He has extensive experience with native fish movement, fishway design and construction.
“We need to design fishways and environmental flows that work together to pass native fish upstream so they can complete their breeding,” said Dr Stuart.
“We need to get fish passages right. Not just to help fish move at a local scale, but also to preserve ‘globally important swim ways’ if we are to maintain our native fish populations.”
Since shortly after the first weir was constructed in the Murray-Darling Basin in 1922, there have been efforts to help native fish move around barriers like dams and weirs using fishways.
Based on the site, barrier, and the fish species, fishways can be a shallow rock ramp, or a series of pools that allow the fish to rest as they move up, or a fish-lift for taller structures like the 15 metre Yarrawonga Weir on the Murray River. They do more than just allow fish to pass a barrier and move up or down stream.
Native fish respond to pulses of water coming down the river to move into the fishway and complete their migrations. As the fish pass through the fishway bottleneck, it presents the perfect opportunity to monitor native fish numbers and health.
Monitoring at the Euston and Mildura weirs showed that fish were having difficulty finding the entrances and moving up the fishways. Weir keepers, fish ecologists and water managers are working together on modifications to try to improve fish passage.
At Mildura fishway they are finding that minor tinkering can make a lot of difference. Following some small changes to help native fish find the entrance, up to 400 Golden Perch were record moving through the fishway each day during high spring flows. This was much greater than the numbers of fish previously reported in the fishway. Golden Perch populations in the mid and upper reaches of the Murray River crucially rely on fish from the lower Murray and Darling rivers to sustain their populations.
Fishways also provide the perfect opportunity to remove invasive fish such as carp using separation cages.
The fishway at Torrumbarry Weir, near Echuca, includes a manual lift where invasive fish can be removed, while native fish continue their way up the Murray River.
At the height of floods in 2023. the workers at the weir were removing thousands of invasive fish every day. These fish would otherwise compete with natives and destroy habitat up and down the system.
“Some of the fish that make it to Torrumbarry Weir are coming all the way from Queensland, so the scale of their life history means we have to manage rivers, fishways and flows over a similarly massive scale,” Dr Stuart said.
“I can happily say that every weir on the Murray all the way to the Coorong has a fish ladder now. So, in theory there is passage or connectivity for fish from the ocean to the Hume Dam, that’s 2000 kilometres.”
https://www.dcceew.gov.au/about/news/fishways