Scientists say a giant leatherback turtle washed up on a Gold Coast beach may be the same animal caught in nearby shark nets days earlier.

Key points:

• A 2.5-metre leatherback turtle has been discovered dead on a Gold Coast beach
• Marine scientists say it could have been caught in shark nets
• Experts will conduct tests to help determine the cause of death

The 2.5 metre adult male was found deceased on Mermaid Beach by passers by yesterday.

Marine scientist Siobhan Houlihan, from Sea World, said it washed up at high tide and was thought to be between 30 and 50 years old.

"It's extremely uncommon to see one washed up," Ms Houlihan said.

"They are found in our waters, but they're normally far off shore.

"The last time this happened was about 16 years ago, and the last time we've seen one nest in Australia was 1996.

"If you were to look from the tale tip to the head he'd probably be around 2.5-3 metres in length"

Siobhan Houlihan says whale-watching boats occasionally spot leatherbacks, but it's rare to see the animals close to shore.(ABC Gold Coast: Sarah Cumming)

Foraging for sea jellies

Ms Houlihan estimated the leatherback weighed about 400 kilograms.

She said the species' main diet was sea jellies, and the animal could have been following its food source closer to shore.

"We've had some strong easterlies recently which have brought the sea jellies in, so there's a good chance he was coming in foraging on those guys," she said.

"They have a high saline diet.

"A really cool fact about these guys is that their salt glands are twice the size as their brain because of how much salt water they take in."

Council workers have removed the turtle from Mermaid Beach.(ABC Gold Coast: Sarah Cumming)

Leatherback caught in shark net

Ms Houlihan said there were no visible signs of significant injury on the turtle.

"We do know that there was a leatherback caught in a shark net a couple of days ago," she said.

"It was released alive, so we're unsure, but that is a potential.

"There is a smaller injury to the front left flipper, but again, we won't know until we perform that necropsy."

The dead leatherback attracted curious locals, including Austin Langridge and his sons.

"We've seen sea turtles, but never a turtle that big — especially a leatherback," Mr Langridge said.

Eight-year-old Reef Langridge said seeing the creature up close was an interesting experience.

"The teeth are pretty sharp actually," he said.

"It's cool to see it in real life, but also not cool to see it dead."

Council workers used a bobcat to remove the animal from the beach before it was transported to Brisbane.

Scientists hope their examination will provide valuable information about the species, but said the initial autopsy results were inconclusive and pathology results would take up to a week.

"It is really fascinating," Ms Houlihan said.

"But it is also really sad."