Fish passage reopened in Australia over risk of fish deaths — ABC News Australia

A fish passage has reopened in the Australian area of Menindee, allowing fish to move upstream along the Darling-Baaka River to the Menindee Lakes. This is the final season of a three-year trial of the system, launched amid low water levels, poor water quality and fears of another mass fish death event in summer, ABC News Australia reports.

The passage is operated by Finnish company Fishheart. The company expects that up to 50,000 fish may pass through it by the end of May or the beginning of June. About 7,000 fish passed through the system in its first season and approximately 30,000 in its second.

Fishheart said consultations with a local group of Traditional Owners, who share knowledge about fish behaviour, helped fine-tune the system more precisely. The company also upgraded cameras, lighting and artificial intelligence systems to improve fish identification.

Low water levels and algae

The combined storage level of the Menindee Lakes stands at 29%. There has been little rainfall in the catchment, and algae bloom warnings are in place 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, said the passage could reduce the risk of fish gathering in the area near Menindee Weir.

More current news is available on the UA.News Telegram channel Telegram.

According to him, this area has already been the site of major fish death events, including because of fish concentration and shortages of resources, food and oxygen. About 30 million fish died in the area in 2023.

Lay noted that water oxygen levels are currently generally normal, but concerns remain over blue-green algae. They can multiply rapidly in warm weather, in still or slow-moving water, and where there is an excess of nutrients. In large quantities, such algae can reduce oxygen levels in the water, threatening fish with suffocation.

The passage’s future

No decision has yet been made on whether to continue operating the fish passage after the trial ends. Lay stressed that improving the river system’s condition requires not only fish movement, but also sufficient flow, water temperature and quality, as well as the condition of natural habitats.