Menindee fishway reopens for final year of trial ahead of 'hot, dry summer'

A vital fish passageway in the Darling-Baaka River has reopened for its final year of trial, offering a lifeline to fish struggling in the Menindee Lakes' low water levels and poor water quality.

The passageway, which allows fish to travel upstream, is expected to see up to 50,000 fish travel through between now and late May or early June. The technology was installed to help reduce the risk of mass fish kills, including the devastating 2023 event that saw about 30 million fish die in the area.

Improving fish passage

Fishheart co-founder Mika Sohlberg said the increasing number of fish using the passageway each year had come from a better understanding of the river. "The first season we got 7,000 fish, and then around 30,000 fish," he said.

Fishheart regularly consult with a local group of traditional owners, who are able to share advice on fish behaviour. "Obviously the local fish are new to us," Mr Sohlberg said. "It's like going fishing in a new place. When you go the first time in a new place, you hardly ever get a fish. When you go a second time, you might get one fish. But when you've been there 20 times, you get a lot of fish. So it's a local knowledge and it's innovation."

Concerns about water quality

The fishway has reopened as the Menindee Lakes sit at a combined capacity of 29 per cent, with low rainfall in the catchment and algal bloom alerts in effect in parts of the lakes. Cameron Lay, director of Freshwater Fisheries and Threatened Species at the New South Wales Department of Primary Industries and Regional Development (DPIRD) Fisheries, said the fishway could help reduce the risk posed by fish becoming concentrated in the Menindee weir pool.

"I'm certainly worried, however we're here on the banks of the Baaka and we've done a number of things in recent years to try and minimise that risk," he said. "Fish now have the ability to leave the Menindee weir pool which has been the site of a lot of those significant fish kills. Some of that has been because there's been an accumulation of fish and there hasn't been sufficient resources, food, oxygen et cetera, for them to survive."

Mr Lay said there was concern around blue-green algae, although oxygen levels in the water were generally fine. "Things can change very quickly when you get extended periods of 40-degree days," Mr Lay said. "Probably the biggest concern is the potential of a really hot, dry summer."

Future plans

It is yet to be confirmed whether the fishway will be extended after the trial's conclusion, but Mr Lay said the fish passage was only one part of the broader work needed to improve river health. He said outcomes from the recent Basin Plan Review would begin being implemented after they are released in December.

"There's been a lot of focus in sort of purchasing water and water recovery and that has been an essential step," Mr Lay said. "The river can't survive unless it's got sufficient flow so that was probably the obvious and first priority area to focus on. But it's not the only problem that our rivers are facing."