A researcher from the University of the Sunshine Coast (UniSC) in Australia captured on video for the first time a rare — and uncommon — scene of mating between leopard sharks in the wild, in the crystal-clear waters of New Caledonia.
The discovery, made by marine biologist Hugo Lassauce, revealed an unexpected behavior: two males of the species engaged, sequentially, with the same female, in a kind of underwater “trio.” The moment was captured in detail and is described in an article published in the Journal of Ethology.
According to the researcher, this is the first known scientific record of two male Stegostoma tigrinum copulating successively with a female in natural conditions. All the sharks involved were about 2.3 meters long.
“It’s rare to observe shark mating in their natural habitat, but to do so with an endangered species and still manage to film it all was truly exciting. When I returned to the boat, the entire team celebrated,” says Lassauce, who collaborates with the Aquarium des Lagons, in Nouméa.
For a year, the scientist conducted weekly dives about 15 km from the coast, as part of the aquarium’s monitoring program. Over that period, he had witnessed courtship behaviors between males and females, but had never managed to observe a complete mating — until now.
“I was monitoring a group of leopard sharks when I saw a female accompanied by two males gripping her by the pectoral fins, on the seabed. I asked my colleague to move the boat away, to avoid interference, and I stayed on the surface to watch,” explains.
“I waited about an hour, trembling with cold, until they finally began to ascend. The mating was quick — the first male took 63 seconds, the second 47. After that, both remained motionless on the bottom, exhausted, while the female swam away energetically,” adds.
The two males had already been identified in earlier dives, some dating back to 2018.
Known also as the zebra shark, because of the stripes that juveniles display before gaining the typical spots, the Stegostoma tigrinum is a coastal species of the Indo-Pacific region, classified as endangered by the International Union for Conservation of Nature (IUCN). Until now, its reproductive behaviors were virtually unknown outside of captivity.
The study, co-authored by UniSC researcher Christine Dudgeon — a specialist with more than 20 years of work with leopard sharks —, the aquarium’s scientific director Olivier Chateau and research assistant Hugues Gossuin, offers a new perspective on this less social species.
“These images show that the area where they were captured may be a crucial reproductive habitat. This could help guide conservation measures and also improve understanding of the species’ population patterns and behaviors,” explains Dudgeon.
This type of observation could also be useful for artificial insemination programs aiming to reintroduce the species into the wild — initiatives already underway in countries such as Australia.
“It is remarkable to have seen two males involved in this process, one after the other. From a perspective of genetic diversity, we want to understand how many males actually contribute to the eggs that females lay every year,” concludes.
