A sperm whale washed up on a beach died with plastic sheeting in its stomach, a post-mortem examination has found.
The animal was first spotted at Hell's Mouth, near Abersoch, Gwynedd, on Tuesday evening and later died.
It was the first sperm whale to be washed up in Wales since records began in 1913 - though a related pygmy sperm whale was found in June.
The plastic was not the only piece of marine rubbish the 6.7-metre (22ft) long mammal had eaten.
Rob Deaville, project manager for the Zoological Society of London's cetacean strandings investigation programme, said several pieces of marine debris were found in the animal's stomach.
"It is not possible to accurately assess whether the ingestion of debris was a result of the whale's presence in the abnormal habitat of shallow waters around the UK, or if other underlying issues may have played a role in their ingestion," he said.
"However, it may have had some impact on the animal's ability to digest any ingested prey.
"A large piece of blue plastic sheeting was found in the stomach and a relatively large mass of ropes."
There was also fishing line "and other plastic fragments, seaweed and minor nematode parasites".
The debris had not become impacted and blocked the stomach.
Tests are now being conducted to shed light on this "markedly unusual" out-of-habitat stranding.
The male calf was the second smallest sperm whale ever recorded in the UK.
Because the whale was so small it is thought it may have come from a matriarchal pod rather than rather than a bachelor pod.
The former are found in temperate and tropical waters south of the UK while the latter are found in colder waters north of the UK.