“There are dead fish everywhere,” Menindee resident Graeme McCrabb said on Sunday, describing the smell of the Darling-Baaka River in New South Wales as deep and pungent. Among the dead fish are native species such as bone bream, Murray cod, golden perch, silver perch and carp, he said.
The video he took from his boat showed a thick carpet of silvery fish carcasses above the water.
Australian officials have been aware of the disaster since Friday, acknowledging “a developing large-scale fish kill event” involving millions of carcasses in the river. The New South Wales Department of Primary Industries (DPI) blamed low levels of oxygen in the water, known as hypoxia, as floodwaters recede.
“The current warm weather in the region is also exacerbating hypoxia, as warmer water holds less oxygen than cold water, and fish have higher oxygen requirements at warmer temperatures,” said the agency on Friday in a statement.
McCrabb said the same remote area had recorded large-scale fish deaths in December 2018 and January 2019, calling them a result of poor quality water entering the river, which is often used for fishing. But this time, McCrabb said, the disaster is much worse, and many townspeople are “angry and disappointed” that officials don’t seem to have learned from previous mass fish deaths.
“No one was ready for what was seen here,” McCrabb said, adding that officials had “failed in their duty” to manage the river and collect data to help prevent such disasters.
“If you know the water quality is good or bad, you can make more informed decisions about how water is discharged downstream from lakes and avoid sending black water downstream to kill fish. “, said McCrabb.
Black water events occur “during floods when organic material is washed away from the bank and floodplain and into the river system,” according to the New South Wales Water Department.
The government said the dead fish were mainly bony herring, a species that experiences ups and downs in numbers.
“It ‘explodes’ in population numbers during periods of flooding and can then experience significant mortalities 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 under extreme conditions such as the rising temperatures currently seen in the region.”
Cameron Lay, director of freshwater environments at DPI Fisheries, described the situation as “very distressing” and warned that temperatures over 100 degrees in the region could bring more challenges.
“This in itself may 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 available to us,” he said, according to the Australian Broadcasting Corp.
Accelerating climate change is warming waters and cooking creatures in their own habitats, experts say. Many species suffocate because warmer water cannot hold as much dissolved oxygen.
A study published last year found that if greenhouse gas emissions continue to rise, around a third of all marine animals could become extinct within 300 years.
Ocean animals face mass extinction due to climate change, study finds
The remote location of the recent fish deaths, in the far west of the state of New South Wales, only compounds the disaster. The rotting fish cover has been visible for at least three days. “It’s hard to get people here in a rush,” McCrabb said. “If you try to choose [the fish] upwards, you will probably break them and leave a fish soup. There really aren’t many answers.
Several agencies are working on a response to the disaster, the New South Wales DPI said.
The New South Wales Department of Planning and Environment’s Water Division has acknowledged “a large number of fish deaths” 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 New South Wales Government have exacerbated the impact of our climate change,” said Rose Jackson, Opposition Member of Parliament for New South Wales and Shadow Minister for Climate. ‘Water and Housing, wrote on Twitter. The ecosystem “has been pushed to the breaking point”.
On Sunday, McCrabb said fish continued to die in the water, adding to the already monumental loss of aquatic life. “We started losing more this afternoon,” he said, noting that some of the dead mass was starting to move downstream.
He said more deaths along the river would be likely in the coming days: “We are in a world of suffering here.”
Sarah Kaplan contributed to this report.