The bad news for Nessie hunters is that they found no evidence of large animals and ruled out suggestions that the monster could be a prehistoric marine reptile called a plesiosaur.

The DNA also failed to support theories that a large fish, such a sturgeon or a catfish, could be lingering in the depths, or that a Greenland shark may be living in Inverness-shire.

However, the researchers did find a “very significant amount” of eel DNA. Juvenile eels, known as elvers, arrive in Scottish rivers and lochs after migrating more than 3,000 miles from the Sargasso Sea. Prof Neil Gemmell, a geneticist from New Zealand’s University of Otago, said: “People love a mystery. We’ve used science to add another chapter to Loch Ness’ mystique.