Australasian Science: Australia's authority on science since 1938

Fish Migration Can Push the Boundary Layer

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A research team from the Threatened Species Recovery Hub has developed a system that could help dwindling numbers of Australian freshwater fish pass man-made barriers to their migration.

“Simple things like dams, culverts and weirs can be enough to prevent fish from migrating, accessing habitat and even escaping predators,” said Dr Jabin Watson of the University of Queensland. “These kinds of barriers are a major contributor to the declines and local extinctions of many Australian fish species.

“When streams pass through a culvert – the pipes under most roads – the flow is concentrated,” Watson said. “This fast flow can be impossible for many fish to navigate as they simply can’t swim that fast for that long. Small and young fish are particularly impacted.”

Native fish in the Murray-Darling Basin are estimated to be at only 10% of pre European numbers. “Many different types of devices have been trialled in Australia to help fish move past barriers like culverts,” Watson said. “Baffles are frequently used, with the aim of giving fish areas to rest along the way, but our laboratory testing has shown that the turbulence created can really knock fish about and make them disorientated.”

The team tested the swimming ability and behaviour of native fish species in a biohydrodynamics laboratory at UQ, and “discovered a completely new approach that...

The full text of this article can be purchased from Informit.