Great Barrier Reef coral spawning begins off Magnetic Island, 45 years after it was first recorded

The Great Barrier Reef’s annual coral spawning season has begun in the waters off Magnetic Island, Queensland. Corals across the reef are releasing egg and sperm bundles into the ocean at the same time, in a spectacle often described as an underwater blizzard.

The event lasts just a few days each year, happening at night a few days after a full moon. This year’s spawning window was predicted for the nights of 30 and 31 October into 1 November.

This year’s spawning marks the 45th anniversary of the first recorded mass synchronised coral spawning, which scientists observed at Magnetic Island in 1981. It also marks 45 years since the Great Barrier Reef was added to the UNESCO World Heritage List.

Professor Peter Harrison was among the researchers who witnessed that first recorded spawning in 1981. “I vividly remember the first time I saw mass coral spawning at Magnetic Island,” he said. “I was overwhelmed with the scale of the event. So many different types of corals were releasing eggs and sperm together and the eggs sperm bundles filled the area and floated to the surface creating one of nature’s greatest underwater spectacles.”

His research later led to coral IVF, a technique that grows coral larvae in floating pools and moves them to damaged sections of reef. It has been used to help renew the Great Barrier Reef and reefs around the world.

Why it matters

Spawning is how the reef renews itself: the bundles released now become the next generation of corals, even as the reef faces pressure from warming seas and other threats. Harrison called the reef “a world heritage icon” and said it was Australia’s responsibility to manage it effectively, noting it is the largest coral reef system on the planet.

The timing also matters locally. The Port of Townsville has said it will not dredge until 4 November, when it plans to dump sediment at sea 6 kilometres from Magnetic Island’s shores. Nearby residents have raised concerns the dumping could harm reef reproduction.

What happens next

The spawning is expected to continue for a few more nights, with a second window predicted for late November. The port’s dredging is due to start on 4 November, and attention will turn to whether the sediment dumping affects young corals settling on the reef.

Sources

• https://aapnews.aap.com.au/news/underwater-blizzard-coral-spawning-season-kicks-off (AAP, 31 October 2026)
• https://www.ad-hoc-news.de/unterhaltung/reisen/great-barrier-reef-coral-spawning-begins-on-31-october/70439243 (ad-hoc-news, 31 October 2026)
• https://umlegacypressqsefc.com/concern-as-queensland-port-plans-sea-dump-in-coral-spawning-season/ (UM Legacy Press, 28 October 2026)

This article is for general information and education only. It is not legal or financial advice.