Invasive Weather Loach Swarms Take Over Irrigation Filters Following Major Flash Flood in Australia

Thanks to a surge in their population brought on by a recent major flood, swarms upon swarms of slimy gray fish are clogging irrigation water filters in Australia.

Invasive species like weather loaches are a problem in Australia, particularly in rivers like Murray.

Ornament to Invasive Species

Gulbali Institute of Charles Sturt University's, Lee Baumgartner, the executive director, and Fisheries and River Management professor, said that the weather loach is an invasive species that was released into rivers as an ornamental species.

They are marketed as ornamental species in aquarium stores, but owners have introduced them to the river systems.

They have developed wild populations over time.

These fish typically have a mottled yellow-brown color with some black spots and a long, cylindrical body that resembles an eel.

They have a maximum length of about ten inches.

John Koehn, a Charles Sturt University freshwater fish ecologist, told Newsweek, that The fish are a highly adaptable invasive species that can survive in the mud beneath the floodplain surface and reappear later.

Over the past 20 years or so, there has been a weather loach invasion of the 125-mile Murray river.

It is unclear how they affect native fish in Australia.

However, there has been a considerable dietary overlap with the local Mountain Galaxias, which could result in the loach out-competing the native species for food and resources.

The weather loaches are known to carry several parasites that are not native to Australia and may also eat the eggs of native species.

Western Murray Irrigation (WMI) claims that they have never encountered this issue before, not even during previous floods, according to a report from NSW Irrigators' Council.

Murray-Darling River and Floods

One female can produce up to 100,000 eggs in her lifetime, and the fish can withstand low oxygen levels, according to the NSW Department of Primary Studies.

More than 3,000 homes in South Australia alone have been affected by recent severe flooding in the Murray-Darling River basin, which makes up 14% of Australia's enormous landmass.

These kinds of floods have the potential to dramatically increase the population of weather loaches, particularly if they take place during the breeding season.

According to Baumgartner, every time there is a flood, the fish population increases.

This year, the Murray-Darling basin has seen an increase in its population, and previous floods have also brought this about.

The floodplain offers ideal conditions for spawning and larval egg survival.

This year's flooding occurred during their breeding season.

Up to 8,000 eggs can be laid by a female in a single spawning. According to the NSW Irrigators' Council, there were so many weather loaches in the river this year that they managed to get past fish screens and congregate in irrigation water pumps.

The Murray-Darling fish and their interaction with fish filters are a much bigger problem than the clogged pump that can be seen in the image.

According to Baumgartner, there has been a significant amount of work done to create fish-friendly screens that safeguard farmers' pumps, and fish, and prevent this from happening.

Several solutions are now open and being implemented all along the Murray-Darling river, thanks to a team of scientists that have been working to address this issue.

Native Species and the Flood

In essence, the river basin has experienced severe drying and deterioration of water quality as a result of water extraction for use in irrigation and other purposes.

To guarantee minimum river flows for critically important environments and downstream communities, Richard Kingsford, University of New South Wales Sydney's director of the center for ecosystem science, stated that they needed to reduce water extractions and redistribute water on this iconic river in 2022.

His paper on water problems was published in Transactions of the Royal Society A: Mathematical, Physical, and Engineering Sciences.

Although the flooding may have aided invasive species in their growth, it has also benefited native species that were having trouble surviving because of the water allocations for the basin.

However, Koehn noted that native fish species like golden perch, as well as waterbirds, plants, and another native biota, have benefited greatly from this flooding.

Rivers and floodplains have come back to life as a result.

This is a part of Australia's drought-flood cycle, which the UK and Europe are less accustomed to or familiar with, Newsweek reported.