Baby fish lured home by fried bacon
Baby reef fish that have drifted too far from home rely on a cacophony of sound, including the sound of frying bacon, to guide them back, new research suggests.
Scientists who worked on Australia's Great Barrier Reef publish their study in today's issue of the journal Science.
After fish larvae hatch from eggs on the reef, ocean currents carry them out to sea.
But once the little blobs of larvae have grown into strong swimmers, they need to listen to sounds of the reef to find their way back.
Researcher Dr Mark Meekan, currently scientist in charge of the Australian Institute of Marine Science (AIMS) in Darwin, but based with AIMS on Lizard Island for the research, says creatures on the reef make an "incredible and bizarre" array of noises.
These range from the sound of frying bacon that snapping shrimp claws make, to trumpeting, drumming, crackling, whistling and the sound of sawing wood.
"It was kind of an unexpected result, because a lot of people don't even realise that fish have ears to start off with, let alone that they use them to find their way home," Meekan says.
"The funny thing is that fisherman have known about these sounds for years; that's why they've named fish 'trumpeters' or 'drummers'."
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(Sound: Rob McCauley)
The researchers built 24 artificial reefs and outfitted half with speakers broadcasting reef noise.
They discovered that two common types of reef fish larvae, cardinalfish and damselfish, settled in greater numbers on the noisy reefs than on the quiet reefs.
The researchers also found the damselfish had a distinct preference for high frequency sound, while the cardinalfish were attracted to both low and high frequency sound.
Meekan says the finding that certain species prefer sounds of certain frequencies raises the question of whether human noise could be interfering with marine communication.
"Humans make a lot of noise near certain reefs. We have turbine intakes for power stations, and a lot of shipping noise," he says.
"The concern is that this human-made noise may actually be blotting out the sounds that these baby fish need to make it back to reefs."
But Meekan believes the research could be used in the future to attract baby fish to depleted reefs or marine conservation reefs.