Fish have ears, so man-made noise threatens their survival

April 10, 2018, University of Exeter

An 'acoustic fog' from motorboat noise, underwater construction and other man-made marine sounds can threaten the survival of fish and their ability to communicate with each other, research has found.

A BBC film (link below) made with Professor Steve Simpson, an expert on marine acoustics at the University of Exeter, reveals that man-made noise is interfering with fish's ability to defend themselves against predators. It is also compromising their ability to communicate with each other when they hunt, or to find and attract mates.

Research has also shown that human noise can hamper the development of some young fish, with some born malformed and others failing to hatch at all.

The importance of the marine soundscape to the survival of fish becoming much easier to explore thanks to the use of advanced hydrophones by marine biologists. The technology was originally developed for military use underwater.

Professor Simpson, who recorded the communication of clownfish on Blue Planet II, reveals in a new film for BBC Earth that 'fish have ears' and that they talk to each other, through a variety of different languages, ranging from the crackling sound of snapping shrimp, to the chirping sounds of damselfish to the clicks of clownfish.

Fish also communicate with each other while hunting together, to warn each other about the approach of predators and to impress each other during courtship.  

Professor Simpson said there was a 'full orchestra' of sounds from the communication of marine life but that this is being drowned out by human noise from boats, pile driving, the use of dynamite in fishing and the quest to find untapped oil and gas reserves. 

The man-made noise is affecting marine life from plankton to whales. 

Professor Simpson said: "We are only now beginning to understand the full impact of man- made noise on fish and to assess impacts on how they communicate with each other.  The sound of a motorboat can mask all natural sounds while it passes, and larger ships can be heard from many miles away. But I remain optimistic that action can be taken to reduce man made noise within the next 20 years as the impact begins to more fully understood. By learning to listen, we can help restore the natural acoustic conditions that many marine animals depend upon."

Read more at: https://phys.org/news/2018-04-fish-ears-man-made-noise-threatens.html#jCp