“There are dead fish everywhere,” Menindee resident Graeme McCrabb said Sunday, describing the smell in New South Wales’ Darling-Baaka River as far-reaching and pungent. Among the dead fish are native species such as bony bream, Murray cod, gold perch, silver perch and carp, he said.
Video he took from his boat showed a thick carpet of silver fish carcasses on top of the water.
Australian officials have been aware of the disaster since Friday, acknowledging “an evolving large-scale fish kill” involving millions of carcasses in the river. The New South Wales Department of Primary Industries (DPI) blamed low oxygen levels in the water, known as hypoxia, as the floodwaters recede.
“The region’s current warm weather also exacerbates hypoxia, as warmer water holds less oxygen than cold water and fish require more oxygen at higher temperatures,” the agency said in a statement Friday.
McCrabb said he had the same remote area recorded large-scale fish kills in December 2018 and January 2019, citing them as the result of poor-quality water flowing into the river, which is often used for fishing. But this time, McCrabb said, the disaster is much worse, and many in the city are “angry and disappointed” that officials don’t seem to have learned from the previous mass fish kill.
“No one was ready for what was seen here,” McCrabb said, adding that officials had “failed to fulfill their duties” to manage the river and collect data to help prevent such disasters.
“Knowing the quality of the water is good or bad can help you make more informed decisions about how water is discharged downstream from the lakes and avoid sending black water downstream to kill fish,” McCrabb said.
Blackwater events occur “during flooding when organic matter is washed away from the riverbank and floodplain and into the river system,” according to the New South Wales water department.
The government said the dead fish were mainly leg herring, a species that is rising and falling in numbers.
“It ‘booms’ in population during floods and then can experience significant deaths or ‘busts’ when flows return to more normal levels,” DPI Fisheries said. “They may also be more sensitive to environmental stresses such as low oxygen levels, especially during extreme conditions such as elevated temperatures currently being experienced in the area.”
Cameron Lay, director of freshwater environments at DPI Fisheries, described the situation as “very distressing” and warned that temperatures above 100 degrees in the area could create more challenges.
“That in itself can pose an ongoing risk to water quality and native fish, so we will do everything we can to monitor the situation and use all management options at our disposal,” he said, according to the Australian Broadcasting Corp.
Accelerating climate change is heating up the water and cooking creatures in their native habitats, experts say. Many species suffocate because warmer water can’t hold as much dissolved oxygen.
A study published last year found that if greenhouse gas emissions continue to rise, about a third of all marine life could disappear within 300 years.
The remote location of the recent fish kill, in the far west of the state of New South Wales, only exacerbates the disaster. The rotting blanket of fish has been visible for at least three days. “It’s hard to get people here in a hurry,” McCrabb said. “When you try to choose [the fish] on, you’re probably going to break them up and leave a fish soup. There aren’t really many answers.”
Multiple agencies are working on a response to the disaster, the New South Wales DPI said.
The water division of the NSW Department of Planning and Environment acknowledged “a large number of fish kills” and said “Dissolved oxygen levels remain a concern for fish health.”
“The reality is that the Darling River is very sick. Years of mismanagement by the NSW government have exacerbated the impact of our changing climate,” Rose Jackson, an opposition member of the New South Wales Parliament and shadow minister for water and housing, wrote on Twitter. The ecosystem “has been pushed to breaking point.”
On Sunday, McCrabb said fish are still dying in the water, adding to the already monumental loss of aquatic life. “We’re starting to lose more this afternoon,” he said, noting that some of the dead mass had begun to move downstream.
He said more deaths are likely to occur along the river in the coming days: “We are in a world of pain here.”
Sarah Kaplan contributed to this report.