Three leopard sharks – 2 male and 1 female – in the process of mating. Credit: UniSC
Three wild and frisky leopard sharks have been caught in the act of copulation by a scientist snorkelling at Abore Reef, 15km off the coast of Noumea, New Caledonia.
Roughly 90 minutes of lead up involved the males latching onto the female’s caudal and pectoral fins, remaining almost motionless on the seafloor. The main event, in which each male took a turn to mate with the female, was over in just 110 seconds.
This is the first documented observations of group mating for the species. The exploits have been described in a new study in the Journal of Ethology.
“I’d seen males swimming fast after females before and I’d arrived ‘on the scene’ just after a male and female separated, but I’d never seen the whole sequence,” says Lassauce.
“Then while I was surveying this particular aggregation of leopard sharks, I spotted a female with 2 males grasping her pectoral fins on the sand below me.
“I told my colleague to take the boat away to avoid disturbance and I started waiting on the surface, looking down at the sharks almost motionless on the sea floor.
“I waited an hour, freezing in the water, but finally they started swimming up. It was over quickly for both males, one after the other. The first took 63 seconds, the other 47.
“Then the males lost all their energy and lay immobile on the bottom while the female swam away actively.” The female had visible wounds on each of her pectoral fins.
“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.”
Three leopard sharks – 2 male and 1 female – in the process of mating. Credit: UniSC
Leopard sharks (Stegostoma tigrinum) are found in coastal waters of the Indo-West Pacific region, from Africa’s east coast to the Pacific Islands including Australia.
They prefer habitats such as coral and rocky reefs, sandy plateaus next to coral formations, inshore mudflats, mangroves and seagrass beds.
The species is listed as endangered by the International Union for Conservation of Nature (IUCN) due to significant population declines and local extinction in the western Indian and southeast Asian regions. This has been driven by overfishing and habitat degradation.
As a result, leopard sharks are mostly studied in captivity and little is known about their natural mating behaviours.
Leopard sharks mating in the wild. Credit: UniSC
“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,” says UniSC Senior Research Fellow Dr Christine Dudgeon, an expert in marine ecology and evolution and co-author of the paper.
She says the findings could also aid artificial insemination research aimed at helping rewild the species.
“It’s surprising and fascinating that 2 males were involved sequentially on this occasion,” she says.
“From a genetic diversity perspective, we want to find out how many fathers contribute to the batches of eggs laid each year by females.”