Sometimes science gets a little scandalous. Marine biologist Dr. Hugo Lassauce was filming Indo-Pacific leopard sharks (Stegostoma tigrinum) off New Caledonia when he caught two males literally locking fins with a female in a rare shark ménage à trois. This isn’t an “Oh! Avert your eyes!” moment for the science world (although the video is available to watch with the published article) — it’s one of the first times anyone has seen leopard sharks mating in the wild, and for a species teetering on the brink in parts of Asia, this is a tantalizing peek into their secret love lives that could help save them.
A distinctive species with large pectoral fins, spineless dorsal fins, and a very long caudal fin, they are generally slow-moving and adults sport a yellow-brown with a covering of dark brown spots, while juveniles display a striking pattern of narrow yellow to white bars and blotches on a brown background. Also known as zebra sharks, they are primarily nocturnal feeders, preying mainly on gastropod and bivalve molluscs, with crabs, shrimps, and small fishes forming a smaller part of their diet. They are oviparous, laying large, dark-colored egg cases that are anchored to the seabed throughout the tropical Indo-West Pacific. Hatchlings often resemble banded sea snakes in both color and in how they swim (undulating like a snake instead of swimming like other shark species), an adaptation that may help them avoid predators. This new insight that New Caledonia’s waters might be an important breeding ground is beyond fascinating: it’s crucial for their survival. Leopard sharks in South-East Asia are facing serious declines from overfishing, making every glimpse of natural reproduction essential for conservation efforts. And seeing the sharks’ mating dance in action helps researchers understand their biology in ways photos or lab studies can’t.
Dr. Lassauce said his team had been monitoring the area for weeks, observing small courtship gestures that hadn’t yet led anywhere. “We have been seeing and observing some courtship events [over several weeks] where the male will try a little bit with the female, but nothing happened,” he told ABC. “This day it just happened … I saw the two male sharks grabbing the female’s fin and I knew the mating behaviour [was] coming soon.” It started with some careful pre-copulation positioning, followed by the males gripping the female’s fins and tail, showing off their siphon sacs, and then thrusting with their claspers. All of these moves had only been seen before in captive sharks. And while pre-mating interactions have been photographed, fully documented sequences like this one are extremely uncommon.
Sharks are notoriously tricky to study in the wild. They travel long distances, inhabit vast oceans, and often behave differently under observation. Documenting natural behaviors ensures conservation measures are informed by accurate ecological knowledge rather than assumptions. This observation is part of the global ReShark collective project, which aims to help leopard shark populations recover in South-East Asia. The Stegostoma tigrinum Augmentation and Recovery Project, or StAR Project, is a global effort to restore endangered leopard shark populations in areas where overfishing and habitat loss have caused dramatic declines. Officially launched in 2020 following a pivotal workshop hosted by Georgia Aquarium, it became the world’s first conservation translocation program for a shark species. The project combines captive breeding, genetics, and careful release strategies with in-situ conservation; only eggs from approved aquariums are transferred to local nursery facilities, where they are hatched, raised, and eventually tagged for release, with post-release monitoring tracking their adaptation to the wild. The project also emphasizes community involvement, engaging local schools and volunteers to foster stewardship, while ongoing research in Australia and New Caledonia provides crucial insights into leopard shark behavior, nutrition, and habitat use.
“Trying to reintroduce the species you need more information on the biology and ecology of the shark,” Lassauce said. “We need to know more about their behaviour, about how far they can swim, how they reproduce … to make sure their reintroduction into [new] environments can be a success.” That is what Lassauce and his team where doing when they came across this… event. Knowing where and how these sharks reproduce, scientists can target breeding grounds for protection and design effective conservation measures; this can influence fishing limits, marine protected areas, and reintroduction strategies in areas where the species has disappeared. But the stakes go beyond the survival of a single species. As predators, leopard sharks play a vital role in maintaining the balance of reef ecosystems, supporting coastal fisheries, and sustaining broader marine biodiversity. Protecting their reproductive behavior ensures these ripple effects continue, keeping entire ecosystems healthier and more resilient.
This new PG-13 observation also reminds us how much we still do not know about the private lives of these enigmatic sharks. How many more breeding hotspots remain unobserved, and what other behaviors critical to their survival are unfolding just out of sight? The challenge now is translating that knowledge into meaningful protections across the Asia Pacific and beyond, ensuring that rare moments like this mating event are not just a fleeting glimpse but part of a sustainable future for leopard sharks. Can global collaborations like the ReShark and StAR Projects provide the blueprint for safeguarding other threatened marine species? Only time will tell. And will our growing knowledge be enough to tip the balance in favor of leopard sharks before human pressures push them past the point of recovery? That answer will ultimately shape the next chapter of shark conservation.
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