Mass fish deaths have occurred in the Darling River, the second longest river in Australia, due to low levels of dissolved oxygen. Hundreds of thousands of fish, predominantly bony herring, were found dead on the surface of the river near Menindee in New South Wales, almost 1,000km west of Sydney. Fisheries officers are investigating and monitoring the situation as rotting carcasses cause a putrid smell for residents. It follows similar mass fish deaths in the same area in 2018 and 2019 as a result of poor water quality and sudden temperature changes.
The NSW Department of Planning and Environment’s water division has warned that oxygen levels in the river may fall further as temperatures rise before cooler conditions return next week. The NSW Department of Primary Industries (DPI) will continue to monitor the area’s fish health, with the agency stating that higher temperatures may increase the amount of stress already placed on fish by the low oxygen levels. Dissolved oxygen levels remain a significant concern for fish health in the region.
The ongoing incidents of mass fish deaths highlight concerns over Australia’s water quality and river management. Climate change is predicted to lead to more extreme weather events, including rises in temperatures and sudden fluctuations in river water levels. Additionally, damming, extraction and agriculture have placed increasing pressure on the country’s water resources. The Murray-Darling river system, which includes the Darling River, is home to 30% of Australia’s agricultural production.
The New South Wales government announced plans to invest AUD 650m ($460m) in water infrastructure projects in February 2019, following media and public pressure over the impact neglectful safety standards were having on the Murray-Darling Basin. The plan includes stricter regulation and higher penalties for environmental offences, but critics say that more needs to be done to ensure that Australia’s precious water resources are managed in a sustainable and effective way. The government argues that it is committed to improving the health of rivers and waterways nationally through its Water for the Environment programme.