A whale washed up on an East Lothian beach has been found to have some of the “most severe wounds” from fishing gear ever recorded.

Scientists said it had probably suffered for months and experienced an “agonising death”.

Experts from the Scottish Marine Animal Strandings Scheme (SMASS) said the Sowerby’s beaked whale was discovered at Gullane Beach after a “horrific entanglement.”

The 14.7ft female, which weighed 102 stones, was found at the weekend and is the latest of such net snaring incidents around the Scottish coast.

“An adult beaked whale [was] chronically entangled with some of the most severe wounds we have recorded,” said a report by SMASS.

“The animal had died on the beach, was in thin body condition and showed severe trauma to the right pectoral fin, large areas of skin loss from the flank, and a loop of thin, green cord embedded around its neck.

“It had been entangled for long enough that the cord had worked its way right through the skin and blubber layer into the underlying muscle layer.

“In some places the skin had grown over the top of the rope; in others it had set up a deep tissue infection and abscessation. There were goose barnacles attached to the rope, an indication the entanglement had considerably compromised the swimming capabilities of the animal."

The report added: “This animal suffered for a long time, certainly weeks, possibly months, ending in what we can only assume was an agonising death. This was a very grim case to witness and extremely concerning from a welfare and conservation point of view. 

“The evidence is the issue is getting worse, affecting an increasingly wide range of species and causing unquantifiable harm and suffering to our marine populations. Everyone is responsible for the current state of our seas. Everyone has the opportunity to improve them.”

Last week SMASS revealed a minke whale killed after becoming snared in fishing nets off Orkney was pregnant. Investigators said it too would have suffered an agonising death – especially over an “exhausting” last few hours – and criticised fishermen who “wilfully” throw gear overboard.

The 28ft adult female came ashore on Sanday on September 28. More than one-sixth of the most common species of whale found in Scottish waters – minke whales – have been damaged by fishing equipment, a previous investigation has revealed.

Fortunately, a giant humpback whale was freed from being snared in fishing gear in Orkney on October 1. A specially trained group of volunteers from British Divers Marine Life Rescue were mobilised to rescue the animal trapped off Westray.

The report was received from a local fisherman who found the animal anchored in his fishing ropes.

Six organisations last year joined forces to tackle the threats posed to marine wildlife, such as seals, whales and dolphins, from lost fishing gear along the coast. The Scottish Entanglement Alliance has said it will work closely with the inshore fishing industry to better understand the scale of the problem. Another aim is to raise greater awareness of it.

In May it was discovered fishing gear that snared a giant humpback whale to its death on the north Caithness coast originally came across the Atlantic from Nova Scotia.

The whale came ashore close to Scrabster, near Thurso. Investigators have probed if the whale got entangled off Canada and dragged the rope and buoy across the Atlantic or – more likely – if the gear floated to off Scotland and then snared the humpback. Humpback whales are at high risk of entanglement in ropes and lines in the water, including the giant snared in fishing gear at Helmsdale, Sutherland.