“With acoustics, we can leave our recorders there for a long time, up to a year, and when something swims by we can detect it.”
The key to the technique is it can only pick up animals that make sound, while many fish, especially native species, remain relatively quiet in their watery homes.
Dr Linke said about 20 per cent of fish species made sounds that could be picked up on the recorders and recognised.
But importantly, many of the “noisy” species are invasive foreign species, meaning unlike above the water, where a noisy bushland suggests a healthy ecosystem, under the surface it is more complex.
Ultimately, Dr Linke said being able to accurately measure noise as an indicator of waterway health was the “holy grail” of the field.
But he said more research was needed to be able to generalise the links between the two factors.
“It’s not as simple as more noisy is more good,” he said.
Dr Linke and his colleagues recently took over the editorial desk of the journal Freshwater Biology for an issue, to highlight the potential of the field of underwater acoustics on research and conservation efforts.
One of the research projects highlighted is a sort of “Shazam for fish”, which would be able to recognise what type of fish was making a noise in real-time.
Another looks at whether fish looking for love emit different noises, while one article looks at the noises Amazonian piranhas use to communicate.
Apart from the scientific outcomes, Dr Linke said the issue was an indicator the sector had a promising future.
“We are extremely proud that nine out of the 15 articles were led by students,” he said.