Human noise ‘leads fish from habitats’

NOISE pollution from shipping, drilling for oil or wind farms could lead fish away from their natural habitat into areas where they could die, potentially devastating future fish stocks.

A British-led team made the discovery while working on the Great Barrier Reef — as well as debunking the myth that fish have three-second memories.

Dr Steve Simpson, of the University of Bristol’s School of Biological Sciences, said: “When only a few weeks old, baby reef fish face a monumental challenge in locating and choosing suitable habitat. Reef noise gives them vital information but if they can learn, remember and become attracted towards the wrong sounds, we might be leading them in all the wrong directions.”

After developing for weeks at sea, baby tropical fish rely on natural sounds made by fish, shrimps and sea urchins as a cue to find coral reefs where they can survive and thrive.

With human noise pollution from ships, wind farms and oil drilling on the increase, this behaviour is coming under threat.

Researchers collected baby damselfish as they were returning to coral reefs.

The fish were then put into tanks with underwater speakers playing natural reef noise or a synthesised mix of pure tones.

The next night the fish were put into specially designed long tubes with contrasting conditions at each end in which the fish could move freely towards the end they preferred with natural or artificial sounds playing.

All liked the reef noise, but only fish that had experienced the tone mix swam towards it.

Dr Simpson said: “This result shows that fish can learn a new sound and remember it hours later, debunking the three-second memory myth.”

His collaborator Dr Mark Meekan said: “It also shows that they can discriminate between sounds and, based on their experience, become attracted to sounds which might really mess up their behaviour on the most important night of their life.”

The study is published today in the journal, Behavioral Ecology.