Thousands of invasive European carp and a small number of native Murray cod have perished in a fish kill at Lake Pamamaroo in far western New South Wales, near Menindee, according to visiting filmmakers.
The filmmaker Rory McLeod and anthropologist Peter Yates, both of Maldon, Victoria, told Guardian Australia they arrived in the area on Tuesday to investigate reports of a possible mass fish kill.
Earlier this week, the NSW Department of Primary Industries had said it was unable to confirm from previously released aerial footage if a fish kill had occurred at the site.
Yates said: “What we found is mainly – I’d say more than 90% – European carp and much less than 1% are cod. I could see no golden perch.
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“In a sense this is a cull of the carp, but there are some pretty big cod too.”
Yates and McLeod said they were only able to see about 20 native Murray cod, a species listed as vulnerable in Australia, among the dead fish. They estimated between 2,000 and 5,000 fish had died.
“It wasn’t really possible to count with any accuracy. I tried to count sections but there’s a lot of bodies and mud and it was pretty hard to move around,” said Yates.
“What’s confronting is the size of them. There would not be one fish under two or three kilos. The Murray cod were probably small compared to what they could be. The carp look like big breeding age fish. It’s actually great to have them out of the system.”
European carp are an invasive species that damage ecosystems and push out native species, and are subject to a national program investigating ways to remove them.
In January, hundreds of thousands of native fish perished in three mass fish kills.
Yates said he thought the Lake Pamamaroo fish kill was down to a drying of the lake that left fish isolated.
He said: “It’s connected to the rapid drying of the lake system, but it’s not caused by the blue green algae like the others. This is purely the lake dried out and there was a deeper part and the fish were trapped.”
Earlier this week the drought minister, David Littleproud, announced a native fish management and recovery strategy, which included $300,000 set aside from an existing emergency fund, for states to manage “urgent and extreme fish death events”.
Littleproud said: “Make no mistake, we are likely to see fish deaths this summer. We’re facing another hot summer with very little water flowing through our rivers.”
He said: “Fish deaths are common during summer but what we saw last year were a major wake-up call about the impact of the drought on our rivers.”
The plan would provide any available environmental water to mitigate fish deaths, support emergency responses, keep a fish deaths database and “contribute to water quality monitoring programs” that would identify risk areas.
The Greens water spokesperson Sarah Hanson-Young attacked the plan, saying Coalition cuts to environmental flows in favour of irrigators meant there was “no water for the fish to survive”.