Cod may have local accents, scientists suggest

Fish romance may be doomed – at least for certain species that migrate away from their traditional spawning grounds, say scientists.

Cod fish use sounds that are similar to a love song to attract a mate, explained British researchers at a science showcase run by the National Environment Research Council (NERC) on Wednesday.

But as cod in the UK increasingly move north to find cooler water, scientists are concerned that local “accents” – and noise pollution – may hamper future breeding.

Male cod vibrate their swim bladders to produce a pattern of sounds, incorporating thumps, growls and a variety of frequencies which stimulate females to release their eggs.

However, research suggests cod bred in different parts of the UK may have different vocal repertoires – or accents – making it difficult for cod to understand their counterparts from another region.

“Recordings of American cod are very different to those from their European cousins, so there is a precedent,” Professor Stephen Simpson of the University of Exeter, who is leading the research, told the Press Association.

“This species is highly vocal with traditional breeding grounds established over hundreds or thousands of years, so the potential for regionalism is there.”

Moving to colder climes

Global warming has seen sea temperatures rise in the UK, prompting cold water species such as cod and haddock to move further north.

Now scientists are conducting experiments to ascertain whether fish with with accents from Cornwall, in the south west of England, can talk to those from Liverpool, located further north – or whether their chat up lines will be lost on them.

Cod spawning grounds are typically quite isolated, increasing the likelihood of each group having its own local dialect.

Noise pollution

There are also suggestions that cod chatter is being “drowned out” by noise pollution – from boats and other marine equipment.

“Listening to fish is a really good way of surveying what is there, and what their behavior is,” said Simpson, whose team have been dragging underwater microphones through coastal waters to capture the communication.

“Given that cod produce a variety of sounds for establishing territories, raising the alarm and attracting mates, we may find that the ‘gossip’ essential to their society is being drowned out,” he told PA.

However the marine biologist said noise pollution could be better tackled with simple tactics, such as boats avoiding cod spawning grounds at key times and research vessels increasingly designed to be more quiet.