Pods of dolphins living off Cardigan Bay were recorded using their own unique dialect, with their whistles found to be at a higher frequency.
Experts on the BBC nature series Wonders of the Celtic Deep studied pods of 240 dolphins as part of the programme.
“Bottlenose dolphins are highly sociable, the group are in constant communication,” the show’s narrator, Dame Sian Phillips, said.
“Each dolphin has its own unique signature whistle and the Cardigan Bay dolphins may have their very own dialect.
“Their whistles are at a higher frequency than those recorded anywhere else in the world.”
Researchers have previously discovered that dolphins in Cardigan Bay have different sounding whistles to other pods found around the UK.
In 2007, marine scientist Ronan Hickey of the University of Wales in Bangor, and experts from the Shannon Dolphin Foundation in Ireland carried out a study on the dolphins.
They digitised and analysed 1,882 whistles from 120 Irish Sea dolphins to find the Welsh dolphins had their own accent.
Speaking at the time, project leader Dr Simon Berrow said: “We’re trying to associate whistle types with different forms of behaviour – like foraging, resting, socialising and communicating with their young.
“One was distinctive and exclusive to the dolphins of Cardigan Bay.
“We’re really building up a dictionary of a whole range of sounds. There are whistles, clicks, barks, groans and a gunshot sound which they might use to stun their prey.”
The discovery comes after other studies showed that cows moo in regional accents and bird calls vary in different parts of the country.