Scientists are undertaking the largest and most complicated coral regeneration attempt ever undertaken on the Great Barrier Reef in an unprecedented new project that could help save dying coral reefs across the globe.

The project has been dubbed by some as 'IVF for the Great Barrier Reef'.

Professor Peter Harrison, from Southern Cross University, said researchers were collecting millions of coral eggs and sperm during the annual and beautiful coral spawning event on the reef this week in the first step of the ambitious project.

"This is the largest larval restoration project that's ever been attempted not only on the Great Barrier Reef but anywhere in the world," he said.

"It's really exciting.

"For the first time we are going to try on a large scale to capture literally millions of eggs and sperm during the coral spawning event. We're building spawn catchers floating off Moore Reef off Cairns."

Those involved say the scale of the project is unprecedented. ( Supplied: Biopixel )

Innovative idea to give coral best chance at life

Professor Harrison said scientists will grow the tiny corals in the floating booms for about a week and when the larvae were ready they would be introduced onto the most damaged parts of the reef.

He said it was all to repair the damage done by the mass bleaching in 2016 and 2017.

"On the Great Barrier Reef we've lost more than half of the corals in those recent two bleaching events," he said.

"The future is not looking good for any reef system around the world unless we can manage climate change.

"We've lost so many corals that fewer corals are able to spawn and rates of fertilisation are going to be lower and the billions of larvae the reef needs to be replenished naturally [won't be produced].

"In the intervening years we need to start working out how to get [restorations projects like this] to a large scale to make it meaningful."

Scientists are taking coral spawn, raising it and introducing the coral larvae back onto the most damaged parts of the reef. ( Supplied: Katie Chartrand )

El Nino forecast makes human intervention more vital

The Bureau of Meteorology predicts a 70 per cent chance of an El Nino weather pattern forming this summer, which is associated with warmer, more extreme temperatures and fewer cyclones.

"It's really urgent we do this now — starting this year, because we face the potential for another massive El Nino developing and a consequence of that will be increased sea temperatures and a high likelihood of yet another major bleaching event," Professor Harrison said.

Great Barrier Reef Marine Park Authority chief scientist David Wachenfeld agreed and said that coral will continue to be stressed as temperatures rise.

Great Barrier Reef Marine Park Authority chief scientist David Wachenfeld ( Supplied: GBRMPA )

"The concern is as humans change, the climate the world is warming up, the reef is warming up — and that means conditions that lead to coral bleaching and coral mortality are happening more frequently and are more severe," he said.

"At the moment the reef is fighting for survival, it's battered and bruised, but it's resilient.

"But if we continue the way we are, the reef won't be able to keep up and there won't be anything we can do locally, so it's absolutely vital we do everything we can do to reduce greenhouse gases.

"We need to tackle climate change locally but at the same time we're working with scientists to develop techniques to help us in the future."

Marine researcher Katie Chartrand said the project was being run in collaboration with James Cook University, Southern Cross University and the University of Technology Sydney with help from international researchers and tourism organisations.

"We have 55 people involved in this project," she said.

"We also have teams coming over from the Philippines to take part."

While most of the coral spawn is being grown on the reef, some has been taken back to labs where scientists will experiment further to work out how to best promote growth

Ms Chartrand said spawning coral relied on algae to grow.

She said researchers in Cairns were using coral spawn collected by scientists on the reef this week to test which types of algae gave coral the best chance at life.

Scientists have set up floating booms ready to catch the coral spawn this week. ( Supplied: Biopixel )

Reef restoration project could go global

Professor Peter Harrison (pictured) is leading the project. ( Supplied: Biopixel )

Professor Harrison said the scale of the operation was unprecedented but needed to be expanded further.

"This project is the first large-scale attempt to get millions of larvae back onto the reef system in an efficient way," he said.

"We then plan to scale it to hectare scales and within the next few years we're aiming for square kilometre scale.

"The scale of the damage on reefs worldwide is overwhelming, more than 70 per cent of the world's coral reefs are already highly degraded, and another 10 or 20 per cent face imminent pressure from growing human populations.

"We have to be operating at these much larger scales into the future."

Ms Chartrand said if the project was successful, it could be applied to damaged reefs all over the world.

"We're not just talking about using this technology here on the Great Barrier Reef, this is something to scale up and make available globally particularly helping to restore the source reefs, those reefs that really help to baby corals to other surrounding reefs," she said.

"[Outside the box thinking] is critical, it's about getting real solutions and getting an outcome for the reef."