Massive fish die-off sparks outcry in Australia | Science

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Massive fish die-off sparks outcry in Australia | Science

A viral video drew attention to water woes in the Murray-Darling Basin.

Rob McBride/Tolarno Station

Australians knew another long drought was hammering the country’s southeast. But it took a viral Facebook video posted on 8 January to drive home the ecological catastrophe that was unfolding in the Murray-Darling river system. In the footage, Rob McBride and Dick Arnold, identified as local residents, stand knee-deep among floating fish carcasses in the Darling River, near the town of Menindee. They scoff at authorities’ claims that the fish die-off is a result of the drought. Holding up an enormous, dead Murray cod, a freshwater predator he says is 100 years old, McBride says: “This has nothing to do with drought, this is a manmade disaster.” Arnold, sputtering with rage, adds: “You have to be bloody disgusted with yourselves, you politicians and cotton growers.”

Scientists say McBride probably overestimated the age of the fish. But they agree that the massive die-off was not the result of drought. “It’s about taking too much water upstream [to irrigate farms] so there is not enough for downstream users and the fish,” says Quentin Grafton, an economist specializing in water issues at Australian National University (ANU) in Canberra. The Australia Institute, a Canberra-based think tank, blamed “policy failure and mismanagement” in a 19 January report, but called drought a catalyst.

Excessive water use has left river flows too low to flush nutrients from farm runoff through the system, leading to large algal blooms, researchers say. A cold snap then killed the blooms, and bacteria feeding on the dead algae sucked oxygen out of the water, suffocating between 100,000 and 1 million fish. The death of so many individuals that had survived previous droughts is “unprecedented,” says ANU ecologist Matthew Colloff. And with fish of breeding age decimated, recovery will be slow. “But only a bloody fool would put a time frame on that,” Colloff says.

This wasn’t supposed to happen. In 2012, the national government adopted the Murray-Darling Basin Plan, touted as a “historic” deal to ensure that enough water remained in the rivers to keep the ecosystem healthy even after farmers and households took their share. But, “The plan didn’t take enough water back for the environment, and then we didn’t use it well,” says John Williams, an ANU hydrologist.

The 1-million-square-kilometer Murray-Darling Basin accounts for 40% of Australia’s agricultural output, thanks in part to heavy irrigation. By the early 2000s, water flows in the lower reaches of the basin were just a third of historical levels, according to a 2008 study. During the millennium drought, which started in the late 1990s and lasted for a decade, downstream communities faced water shortages.

In 2008, the federal government created the Murray-Darling Basin Authority to wrestle with the problem. In 2010, a study commissioned by the authority concluded that farmers and consumers would have to cut their use of river water by at least 3000 but preferably by 7600 gigaliters annually to ensure the health of the ecosystem. Farmers, who saw their livelihoods threatened, tossed the report into bonfires.

The final plan, adopted as national law in 2012, called for returning just 2750 gigaliters to the rivers, in part by buying water rights back from users. “It was a political compromise that has never been scientifically reviewed,” Williams says, adding that “climate change was never considered in the plan, which was a dreadful oversight.”

Implementation has exacerbated the problems. Since 2012, the federal government has spent AU$6 billion on the plan, but two-thirds has gone to improving irrigation infrastructure, on the premise that efficiency would ease demands on the rivers. Critics say the money would have been better spent on purchasing water rights.

Grafton says there are also suspicions of widespread water theft; up to 75% of the water taken by irrigators in the northern part of the system is not metered. Farmers are also now recapturing the runoff from irrigated fields that used to flow back into streams, and are increasing their use of ground water, leaving even less water in the system, says Mike Young, an environmental policy specialist at the University of Adelaide in Australia.

In February 2018, such issues prompted a group of 12 academics, including scientists and policy experts, to issue the Murray-Darling Declaration. It called for independent economic and scientific audits of completed and planned water recovery schemes to determine their effects on stream flows. The group, which included Williams and Grafton, also urged the creation of an independent, expert body to provide advice on basin water management. Young, who wasn’t on the declaration, wants to go further and give that body the power to manage the basin’s water, the way central banks manage a country’s money supply, using stream levels to determine weekly irrigation allocations and to set minimum flow levels for every river.

Before the fish kill, such proposals had garnered little attention. But Young hopes the public outrage will influence federal elections that have to take place by mid-May. The major parties “have to be seen to be committed to expedite improvements to the basin plan,” Young says. The big question then is “whether or not they carry through.”

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