While fish don't have ears that we can see, they do have ear parts inside their heads that can pick up sounds in the water.

 

According to new research, fish react to the noises they hear and boat noise can disrupt orientation behavior in larval coral reef fish.

 

Researchers from the Universities of Bristol, Exeter and Liège conducted a sound study in French Polynesia and found that while reef fish are normally attracted by reef sound, they are more likely to swim away from recordings of reefs when boat noise is added.

 

Natural underwater sound is used by many animals to find suitable habitat, and traffic noise is one of the most widespread pollutants. If settlement is disrupted by boat traffic, the resilience of habitats like reefs could be affected.

 

The study used controlled field experiments with settlement stage coral reef fish larvae. Larvae in a long plastic tube could decide to swim towards or away from a speaker playing back different sounds. In ambient noise equal numbers of fish were found in each section of the tube and in reef noise most fish swam towards the sound. But when boat noise was played along with reef noise more fish swam away from the sound than in reef noise alone.

 

This is the first indication that noise pollution can affect orientation behavior during the critical settlement stage. Growing evidence for the impact of noise on fish suggests that consideration should be given to the regulation of human activities in protected areas.