A Kiwi scientist who has been probing the legend of the Lock Ness monster say there is no evidence the mythic creature exists, though it might be a "large eel".

With over a thousand reported sightings dating back to the 6th century, University of Otago geneticist, Professor Neil Gemmell said one of the most common ideas was there might be a Jurassic-age reptile or population of Jurassic-age reptiles such as a plesiosaur present in Loch Ness.

"We can't find any evidence of a creature that's remotely related to that in our environmental-DNA sequence data," Professor Gemmell said today.

"So, sorry, I don't think the plesiosaur idea holds up based on the data that we have obtained.

The research team carried out investigations into the environmental DNA present in the British Isles' largest and second deepest body of fresh water.

They tested other predominant theories of various giant fish; whether it be a giant catfish or a giant sturgeon, an eel, or even a shark such as a Greenland shark.

"So there's no shark DNA in Loch Ness based on our sampling. There is also no catfish DNA in Loch Ness based on our sampling. We can't find any evidence of sturgeon either," Professor Gemmell says.

The remaining theory that Professor Gemmell cannot refute based on the environmental DNA data obtained is that what people are seeing is a very large eel.

The loch monster, commonly referred to as "Nessie", supposedly has a long neck and one or more humps that protrude from the water.

Evidence of its existence has always been purely anecdotal, with a few disputed photographs and sonar readings.

Popular interest and belief in the creature has varied since alleged sightings came to worldwide attention in 1933.

The new findings came several years after the idea of turning new science toward the myth was first mooted on Twitter.

Darren Naish, the author of a book called Hunting Monsters, used the platform to quiz Professor Neil Gemmell on whether environmental DNA, or eDNA, might be the key to clearing up the mystery.

Environmental DNA, capable of uncovering a wealth of information with just a single water sample, seemed an obvious solution.

Gemmell got an email from John Paul Breslin, a Scottish journalist , asking whether they'd ended up progressing the idea. Though the answer was no, it was still enough to give Breslin an article that quickly spread across the Scottish press - then around the planet.

The response stunned Gemmell.

Professor Neil Gemmell of Otago University has been hunting for the Loch Ness Monster. Photo / Supplied

"In fact, we would have got more publicity out of just saying we'd decided not to do anything at Loch Ness than all of the other work my team had done put together - it was crazy," he told the Herald last month.

Not long after that, Gemmell found himself on a boat in Loch Ness, collecting hundreds of samples from various parts of the lake, some from as deep as 200m.

Choosing to pursue the project obviously posed a potential risk to his scientific reputation, with some colleagues suggesting the idea could be a career-killer.

Yet he also understood that doing science was just one part of a scientist's work; sharing and communicating it was another.

"I felt like for 25 years of my academic career, I'd only just realised how I could be smart about it."