Australian researchers have caught on camera and documented – for what is believed to be the first time – a rare and rather risqué shark mating sequence in wild, suggesting that when it comes to leopard sharks, sometimes it takes more than two to tango.

The surprise discovery was made by Dr Hugo Lassauce from the University of the Sunshine Coast who documented the moment two males and one female of the globally endangered shark species commenced their display in the waters off New Caledonia. The findings were then published in what is now tipped to be this year’s hottest ‘bonkbuster’ – one to rival the next Jilly Cooper novel – a delicately outlined paper in the scientific journal, Journal of Ethology.

It’s believed to be the world’s first recorded and scientifically documented observation of two males of the Indo-Pacific species of leopard shark copulating in quick succession with a female. All three of the sharks measured at around 2.3 metres in length.

Dr Lassauce, a marine biologist and ecologist who collaborates with Noumea’s Aquarium des Lagons, said the team celebrated the scientific and conservation significance of this video ‘as soon as he swam back to the boat. “It’s rare to witness sharks mating in the wild, but to see it with an endangered species – and film the event – was so exciting that we just started cheering,” he said.

The postdoctoral researcher had snorkelled with the sharks 15km off the New Caledonian coast every week for a year as part of the aquarium’s monitoring programme.

“I’d seen males swimming fast after females before and I’d arrived ‘on the scene’ just after another male and female separated, but I’d never seen the whole sequence,” he continued. “Then when I was surveying this particular aggregation of leopard sharks, I spotted a female with two males grasping her pectoral fins on the sand below me.”

“I waited an hour, freezing in the water, but finally they started swimming up. It was over quickly for both males, one after another. The first took 63 seconds, the other took 47. Then the males lost all their energy and lay immobile on the bottom while the female swam away actively.”

Listed as endangered by the International Union for Conservation of Nature (IUCN), the Stegostoma tigrinum has primarily been studied in captivity, with little information on its natural mating behaviour or environmental influences in the wild.

Also known as a zebra shark because its pups are born with stripes that gradually turn into spots, the species is found in coastal waters across the Indo-West Pacific region, from Africa’s east coast to the Pacific Islands and including Australia.

The paper documenting the finding is co-authored by University of Sunshine Coast Fellow, Dr Christine Dudgeon and Aquarium des Lagons’ director and chief scientist Dr Olivier Chateau alongside research assistant Hugues Gossuin. Dr Dudgeon – a marine ecology and evolution expert known for her work with leopard sharks over two decades – said the footage offered great insights into the mostly solitary animals.

“This evidence suggests the site in New Caledonia is a critical mating habitat, which can inform management and conservation strategies as well as help us understand population dynamics and reproductive behaviours more widely,” she said.

These findings could also aid artificial insemination research aimed at helping ‘rewild’ the species, currently underway between countries, including Australia.

“It’s surprising and fascinating that two males were involved sequentially on this occasion,” said Dr Dudgeon. “From a genetic diversity perspective, we want to find out how many fathers contribute to the batches of eggs laid each year by females.”

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