Coral Spawning Barrier Reef

Coral Spawning on the Great Barrier Reef

Every November and December as the tropical summer approaches, Marine Biologists that live in Port Douglas get excited about Coral Spawning.This is the one and only opportunity the reef as an ecosystem  gets to  repair damage from cyclones and Crown of Thorns starfish the two greatest destroyers of coral cover and responsible for around half of the coral destroyed in the last 30 years. Picking when the coral is going to spawn is the scientific equivalent of picking the trifecta in the Melbourne Cup! The Great Barrier Reef Coral Spawning is a profound experience as many species of corals release clouds of egg and sperm bundles (gametes) simultaneously for fertilization.
Coral Spawning is often likened to a reverse underwater snowstorm, with millions of gametes, usually pink or white, drifting upwards towards the surface.Eggs are usually pink but can be quite a few shades either side of white to mauve.
Coral Spawning is notoriously difficult to predict. In fact, each year, some of the Port Douglas marine biologists have been known to run a sweepstake on when the reef will actually spawn.
There are a few indicators for the initiation of the Great Barrier Reef coral spawning event, but even so, predicting it is very problematic. A lot of the time it just boils down to being in the right place at the right time.
Coral spawning happens at night, after the ever-increasing water temperatures have stimulated coral to develop the eggs and sperm. Coral spawning usually occurs over a few days after a full moon and it doesn’t all happen at once on the same night. Different areas of the reef and different species of coral spawn at different times. Coral spawning also occurs at different times for inshore reefs and offshore reefs.

This year was particularly tricky – split coral spawning because the lunar sequence straddles the temperature trend this year. November full moon is too early in the temperature trend and December full moon is too late. Biologists were expecting a mild (if at all) coral spawn this week, with bits and pieces going off through the week. Which is what we got.

Our reef experts are predicting that December full moon will be when the biggest Coral spawning event will occur this year (as temperature will be well past trigger point of 26/27) so will likely go off early – like day 3 or day 4 which is around December 8th, 9th and 10th.

Because of the unpredictable nature of Coral spawning, Great Barrier reef tour operators are usually unable to successfully predict or run tours that allow their clients to do a night dive and experience it. Or they will run a coral spawning tour but not guarantee that you will actually SEE the coral spawning. Even if you don’t get to experience coral spawning, these tours can still be a great experience for people wishing to see the night shift of the Great Barrier Reef.
If you are keen on trying to see the coral spawning on the Great Barrier Reef Port Douglas Reef Charters would suggest that you charter your own boat for a few nights to maximize your chances.

Carolynne Staines
Carolynne Staines

Carolynne has been a Port Douglas "local" since 1995 Her travels have taken her far and wide, from Southern Australia to Europe, from Port Douglas to Cape York, Lizard Island and many places in between. With a career in tourism spanning decades that has seen her manage hotel tour desks in five star resorts, as well as manage tour boats in Port Douglas; she enjoys writing about the best possible experiences of tours and activities around Port Douglas and of course her favorite destination...the Great Barrier Reef.