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Steve Simpson has been listening to fish for 15 years. The marine biologist from the University of Exeter wants to find out what they sound like when they are hunting, when they are breeding, and what happens when fish with different “dialects” collide, as warming seas drive species north.

“Initially I wanted to understand how fish can use sound to navigate at night and select habitat to live in,” Simpson tells WIRED. “But my group and I have now been identifying animals that make the sounds and decoding the meaning of different kinds of sounds. For example, we find the sounds of a reef indicate the quality of the habitat and the composition of the local community.”


His fascinating new study into Britain’s marine soundscape and fish accents has been launched today, October 5, with Simpson presenting the work at science showcase Into The Blue in Liverpool. To coincide with the launch, Simpson and his team will be making live recordings using hydrophones dunked in the Liverpool waters.

They expect to largely pick up sounds of passing ships, ferries and motorboats. “This is now a dominant component of many marine soundscapes, and much of the work of my group and I looks at how human noise is drowning out natural sounds, and even causing stress and behavioural changes in fish. I have one student (Harry Harding) exploring impacts of noise on salmon, and another (Tim Gordon) exploring impacts of motorboat noise on coral reefs.”

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“Seawater is hundreds of times denser than air, so sounds travel much faster and further. We have found that fish on coral reefs are susceptible to noise pollution but we are yet to study the effects in our own waters, which are some of the busiest in the world.”

There has already been some work into regional fish accents - Simpson points to studies carried out by Eric Parmentier into coral fish. They found clownfish can have distinct accents. Now, Simpson's team is listening closely to wild cod, and has already found distinct differences between the American and European species.

“We are interested in cod, partly because they are an iconic European species; partly because they have elaborate mechanisms of making sounds through vibrating their swim bladder,” Simpson tells WIRED. “And partly because they have a wide vocal repertoire with opportunity to diversify their song."

“The American sounds are deeper, short thumping sounds, while the European ones are higher in frequency and the growls are more prolonged. This suggests that regional dialects may exist, such as are seen in birds and mammals - including humans!”


Cod are incredibly vocal, says the professor, and have enjoyed established breeding grounds for hundreds and sometimes thousands of years. As sea temperatures rise, however, the dialects are starting to collide as cod migrate further north.

Rather than tracking the complex consequences of these extreme changes by “counting dead fish on a boat”, Simpson and his team plan to “listen to fish while they perform key tasks including hunting, guarding territories and breeding”. The ultimate plan is to build an extensive sound library to record the British marine soundscape - he and his team have begun with the waters around Newcastle and the Clyde.

“Cod produce a variety of sounds using their swim bladders, to establish territories, raise the alarm and attract mates. We may find that the ‘gossip’ essential to their society is being drowned out. If we value our fish stocks – or our Friday night fish supper – we need to understand this.”