For much of the year, the world’s largest fringing reef is also home to the world’s largest fish.
Hundreds of whale sharks visit Western Australia’s Ningaloo Reef annually, with as many as 60 sighted in a single day during the peak feeding period.
Their presence also brings a festive atmosphere to the coastal town of Exmouth, more than 1,200 kilometres north of Perth.
But, like all great parties, the music must stop eventually, and come early summer, the whale sharks tend to dwindle in numbers.
Laundry list of destinations
Brad Norman, a research fellow with Murdoch University’s Harry Butler Institute, says where the whale sharks go when they leave Ningaloo is one of the big questions.
“We have done a lot of satellite tracking and some of the whale sharks go all the way up to Indonesia,” Dr Norman said.
“Some go directly west, only about 500km, then come back.
“Some have gone down to Shark Bay and even right down to Perth.”
Dr Norman has frequented Ningaloo Reef for the study of whale sharks since 1995.
He is behind some of WA’s most comprehensive whale shark tracking programs and the Wildbook for Whale Sharks, a citizen science photo-identification library powered by a NASA algorithm.
Dr Norman says, while researchers are beginning to understand whale shark migration, the animals’ laundry list of destinations offers an indication that things are not straightforward.
“They can dive down thousands of metres,” he explained.
“The deepest we’ve recorded a whale shark is almost 2,000 metres and they can spend months down at a time.
“Putting electronic tags on animals that can go that deep … it’s been quite challenging to understand where they actually travel to.”
Longer than usual season
Tourism WA officially describes whale shark season as stretching from March to July, but tour operators say they’re far from stowing their sails this year.
Aerial spotter Tiffany Klein has flown above Ningaloo Reef for 14 years.
She says locals have noticed a particularly prolific season in 2024.
“It gives so many more people opportunities to see them and it’s great for all the businesses because they get to run a lot longer,” Ms Klein said.
“I’ve never seen numbers like this in October, ever.”
Tour operator Meghan Loughery said her company had begun running tours through to mid-November.
“I have so many people come in and go, ‘Oh my God, I never knew that they would still be here this late,'” she said.
Warming temperatures
Experts say there could be several reasons why whale sharks are sticking around Ningaloo Reef.
One explanation is that, with more boats hitting the water in recent years, scientists are only now discovering the full extent of the reef’s whale shark population.
However, drawing on global tracking data collected by researchers like Dr Norman, an associate professor at the Australian National Univesity believes climate change could be having a serious impact.
Whale sharks are especially attuned to sea surface temperatures and prefer a narrow band of tropical waters, venturing only slightly warmer in environments rich with food like Ningaloo Reef.
In a recently published study, co-author Ana Sequeira found rising ocean temperatures were pushing whale shark migration routes toward cooler waters, with an average displacement of 12km each year.
It’s also putting them more firmly in the path of global shipping lanes.
Modelling projects collisions between whale sharks and ships will be 15,000 times greater by the end of this century, should water temperatures continue to rise.
It spells disaster for a species that’s declined in population by over 50 per cent in the last 75 years — largely due to ship strike.
Dr Sequeira says the apparent reluctance by whale sharks to leave Ningaloo Reef may be an early warning sign of a broader change in behaviour.
“Whale sharks are just one of those key species that do come in and stay longer in Ningaloo, likely in association with how the temperatures are going in that particular region,” she said.
Leaving safe harbour
There is no shortage of other dangers which threaten whale sharks during their months-long migration away from Ningaloo Reef.
Large areas of the UNESCO World Heritage site are subject to some of the strictest conservation protections on the planet.