Researchers at Murdoch University in Western Australia have observed pre-mating behaviours in endangered whale sharks at Ningaloo Reef. For the first time, following and biting behaviours were recorded between a mature male and a smaller female, shedding light on their elusive mating rituals. These findings will support conservation efforts and understanding sex biases in whale shark populations. Credit: Harry Butler Institute, Murdoch University.
For the first time researchers have witnessed behaviour in the wild which could reveal critical clues about endangered whale shark reproduction.
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, a World Heritage Site in the northwest coastal region of Western Australia, 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, and one of her supervisors Dr Mark Meekan from The University of Western Australia.
In a new paper Barry explored 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.
“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.”
Insights
While the observed interaction likely did not culminate in mating, 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.
Barry said: “At Ningaloo Reef, and many aggregation sites around the world, males outnumber females with a ratio of one female to three males.
“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.
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.
The study is published in Frontiers in Marine Science.
