For the first time researchers have witnessed behaviour in the wild which could reveal critical clues about how the endangered whale shark reproduces.
Little is known about the pre-mating rituals of the elusive creature, and due to its endangered status, there has never been a more critical time to uncover them.
Annual research expeditions at Ningaloo Reef have taken place from 2009-2024 during the month of May, the peak of the seasonal aggregation of whale sharks.
During the 2024 expedition, a research team witnessed and recorded following and biting behaviours by a sexually mature male whale shark towards a smaller female.
The research team included PhD candidate Christine Barry from Murdoch University's Harry Butler Institute and the Australian Institute of Marine Science (AIMS), and one of her supervisors Dr Mark Meekan, now from the University of Western Australia, who has been running a monitoring program at Ningaloo Reef with AIMS for the past 20 years.
In a paper published today in Frontiers in Marine Science Ms Barry explores the implications of these observations.
"Following and biting are common copulation behaviours in other species within the subclass of cartilaginous fish that the whale shark belongs to," Ms Barry said.
"This is also consistent with previous reports by fishers recounting behaviours they'd observed out on the water of sexually mature males towards females at different aggregation sites."
While the observed interaction likely did not culminate in mating, Ms Barry said the team's observations suggested the whale shark's mating behaviours resembled those of many other species of shark.
The existence of these records not only expands researchers' understanding of the whale shark's mating behaviours, but also provide insights into sex-biases reported in whale shark populations across various coastal aggregations.
"At Ningaloo Reef, and many aggregation sites around the world, males outnumber females with a ratio of 1 female to 3 males," Ms Barry said.
"This could explain why female whale sharks may be avoiding aggregation sites. Particularly for juvenile female sharks, the energetic costs of unwanted attention from males could imply a reason for strong male biases."
This research opens the door for conservation efforts and further exploration into repopulation and protection of the species.
Ms Barry, and PhD supervisor Dr Adrian Gleiss - senior lecturer with Murdoch University's School of Environmental and Conservation Sciences - have been at the forefront of whale shark research.
Their research outputs have included insights into the impacts of tourism on whale sharks and the predation of baitfishes associated with Ningaloo Reef whale sharks.
