From Exeter University
Professor Simpson, who has listened to the vocalisations of fish using sophisticated underwater listening equipment, has identified variations in the “voices” of cod from America and Europe.
Different ‘dialects’ have been found in many animals, from songbirds to sperm whales. Simpson is now exploring whether vocal fish, including cod and haddock, living in different areas around Britain could have localised accents because they gather in the same spawning grounds generation after generation.
Prof. Simpson’s research into bioacoustics and the “soundscape” of Britain’s seas has so far focused on the impact of maritime noise pollution on fish. His group has shown that fish become stressed by noise, make bad decisions when feeding and faced with predators, and that early development is impacted by noisy conditions. He fears noise pollution from maritime construction, speed boats and ships could affect their ability to attract mates, where their vocal behaviour is key to reproductive success.
“Seawater is hundreds of times denser than air, so underwater 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 shipping areas in the world.
“Fish produce a variety of sounds, sometimes using their swim bladders to make thumping and rumblings sounds, to establish territories, raise the alarm and attract mates. In noisy places 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,” he said.
His research into fish has found that American cod make “a staccato, banging, bop bop bop sound” while European cod he has listened to, make a “deep, rumbling growling.” Recordings of American cod are very different to those from their European cousins, so there is a precedent. This species is highly vocal with traditional breeding grounds established over hundreds or even thousands of years, so the potential for regionalism is there,” he said.
Simpson’s work has led him to study fish all over the world, including the Great Barrier Reef where he has recorded the love song of the damselfish. The fish’s song, which he likened to the sound of a windscreen wiper, is used during courtship. He said the sound which distinguishes it from other fish in the sea, could help the damselfish identify other fish of its species within the reef environment.
But he said that climate change could lead to different populations of fish coming into contact for the first time. As sea temperatures rise, fish species such as plaice and cod are migrating north.