Bushfires that continue to ravage Australia may also present a longer-term threat to the natural habitat of native fish populations, according to Australia’s Department of Primary Industries.
According to its report early this month, extensive bushfires across New South Wales pose “additional risk for native fish populations coastal and inland catchments.”
“Fish can be directly impacted during fires through extremely high temperatures, loss of habitat, or be threatened from rapid declines in water quality if rainfall occurs in recently burnt areas,” the report said. “Run-off from rainfall events can wash large amounts of ash and sediment into rivers following fires, causing rapid drops in oxygen levels and threatening the survival of fish populations.”
The bushfire is linked to the reported death of thousands of fish in Northern New South Wales, the department said, and the risks of more fish kills might last for a while. DPI added that the fish kills are impacting both inland and coastal waterways from the catchments in the northern Basin, Border Rivers, Gwydir, Namoi, Macquarie, and Barwon-Darling; as well as the Lower Darling and Lachlan catchments.
In the DPI’s updated fish kill events from 10 to 13 January, hundreds of thousands of dead fish were reported throughout the region, including mullet, catfish, herring, bull trout, Australian bass, and eels in Maclay River.
DPI said that that the fish kills were likely caused by “isolated large rain events moving mud and ash from bushfires through the river system, resulting in a drop in dissolved oxygen levels for native fish.”
Australian Marine Conservation Society (AMCS) fisheries spokesperson Adrian Meder said in a statement that while the rains have been a welcome respite after the fire season, the runoffs in bushfire hit areas are impacting many species, including commercially important seafood like prawns, snapper, whiting, and flathead.
“We welcome this desperately needed rain but there’s a flip-side with all the ash and sediment from the fires that will wash downstream. The recent runoffs have already resulted in fish kill events in our rivers, and this choking water is now making its way down our clear, calm estuaries,” he said. “Coastal estuaries are already under so much pressure. They’re critical habitats for a range of species found nowhere else, as well as many commercially important fish species. It could take years for estuaries in Australia to recover from such devastating impacts, and for Australians to enjoy their abundant waters again.”
He urged Australian government to take preventative action on global warming to try to prevent another disastrous bushfire season.
“Australians recognize that the only way to achieve this is to urgently lower emissions by switching from dirty coal and gas to clean renewable energy," he said. "Australia should be leading the way as a global renewable energy superpower, rather than a global fossil fuel pariah.”
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