Sea-cretions: How dolphins’ poo might unlock the secrets to their behaviour

25 May 2025, 22:36 | Updated: 25 May 2025, 23:08

Bottlenose dolphins have been studied by conservationists in west Wales for decades. Picture: Alamy

By Rose Morelli

Scientists in Wales have started analysing the DNA in dolphins’ droppings - and it’s unlocked a boatload of new data on the species’ behaviour beneath the waves.

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Conservationists in west Wales, Cardigan Bay have been studying a group of over 250 bottlenose dolphins for decades - but up until now, they could only observe them from above the waves.

By forensically examining the DNA in the dolphins’ poo, they’ve learned about the species’ sex and social lives, their diets, and even their family lineage.

Catching the droppings is a fast-paced process, as the clouds of waste appear with little warning, then quickly sink.

Samples need to be quickly scooped out, then sent to University of Aberystwyth for examination.

“In order to be able to conserve them, we need to know why they’re here, and a big missing part of this is what they’re feeding on,” says Dr Sarah Perry of The Wildlife Trust of South and West Wales.

Climate change may also be affecting the dolphins’ diet and availability of food, so examining the dolphins’ waste allows scientists to see which fish species the dolphins are feeding on.

Bronze Dolphin statue overlooking Barmouth Harbour, close to Cardigan Bay in west Wales. Picture: Alamy

“We are seeing large amounts of sardine, sprat and anchovy,” says Dr Niall McKeown, a marine biologist at Aberystwyth University.

“This is quite interesting, because these are species that are known to have increased abundance in Welsh waters in response to, we believe, climate change”.

Waters around the west coast of England have experienced a record-breaking heatwave over the last two months.

The Met Office recorded an average temperature around Cardigan Bay that was 2C higher than average.

Dolphin numbers in Cardigan Bay are falling, but it’s not yet clear what exactly is causing the population to drop.