Overdue investment in projects that will revive native fish populations could contribute to jobs-creation during the pandemic, says a Border co-author of a world-first report.
Charles Sturt University fish ecologist Lee Baumgartner was among 22 contributors to Living Planet Index for Migratory Freshwater Fish, which found migratory freshwater fish species reduced on average by 76 per cent between 1970 and 2016.
"No one has done this on a global scale before, for freshwater fish," Professor Baumgartner said.
"Fish are at nine per cent of what they were before European settlement.
"There's not too much to go before they're at a really bad level."
After mass fish-kills in 2019, Professor Baumgartner said the summer's bushfires had taken their toll, including on Macquarie perch at Mannus Creek, near Tumbarumba.
"We surveyed them a couple years ago and they were doing quite well; there were lots of adults and babies, he said.
"One fire completely destroyed the whole system.
"For those threatened species, they're on such a knife-edge.
"We're really at a tipping point - we either go one way, where we see lots of extinctions and big fish declines, or we take some action."
Professor Baumgartner said the Native Fish Recovery Strategy published in June awaited investment.
"We'd really like to see the attitude towards fish changed and for government to get a bit more proactive towards solutions," he said.
"In the Murray-Darling alone, there's 14,000 barriers to fish migration; that's from road crossings right up to big dams like Hume Dam.
"Hume Dam creates what we call thermal pollution.
"It heats up at the top, and then they release water from the bottom, which is really cold ... it stops fish from breeding, eggs from hatching, and babies feeding.
"It's a pretty simple solution to drain the water from the top and not the bottom.
"There's engineering solutions that could fix it, which weren't known in the 1940s when the dam was built."
Professor Baumgartner said such infrastructure projects could create much-needed jobs, but smaller projects such as reintroducing snags in the Murray River could also make an impact.
"You could get local Indigenous groups involved, fishermen involved - it's stuff that can bring the community together," he said.
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"That sort of thing doesn't necessarily need big money.
"A healthy river is an economic engine.
"When the river is full of water, when the farmers are growing crops around it, when the fish are doing well, and the fishermen are happy, everyone's happy.
"There's an economic reason to get our management of rivers right."