Whale sharks (Rhincodon typus), the world’s largest fish, are known for their vast migrations across oceans in search of food-rich environments. Sure, we know they often follow plankton blooms, fish spawning events, or seasonal changes in water temperature. But a recent study led by scientists from the Australian Institute of Marine Science and The University of Western Australia has found that these gentle giants are drawn to both natural underwater features like seamounts and canyons, as well as artificial structures such as offshore oil and gas platforms. These features, whether natural or man-made, provide critical foraging opportunities by increasing prey availability in the surrounding waters.
The study analyzed satellite tracking data from 78 whale sharks tagged over 14 years at Ningaloo Reef and Shark Bay, two well-known aggregation sites off the Western Australian coast. “We mapped their movements across the eastern Indian Ocean and the North West Shelf. The latter area in particular features a number of oil and gas platforms and associated infrastructure,” said lead author Ben D’Antonio, a PhD candidate from the AIMS@UWA program, in a press release. The data revealed that whale sharks tend to follow paths that connect key feeding grounds, with seamounts and industrial infrastructure acting as stepping stones along their journey. The ocean currents surrounding undersea pinnacles and seamounts enhance the availability of food sources such as plankton. Interestingly, the same phenomenon appears to occur around oil and gas platforms, where artificial lights may attract plankton, creating similar feeding opportunities. While natural features can span tens of kilometers, the relatively small platforms seem to provide a comparable level of attraction for these massive filter feeders.
The study’s findings could have important implications for the future management of offshore oil and gas infrastructure. As platforms reach the end of their operational life, their removal could disrupt migration patterns. “The removal of platforms at the end of their productive life may change seascape connectivity by removing migratory stepping stones that link important habitats for whale sharks,” he said. “There is still a need to understand the detail in the relationships between whale sharks and individual oil and gas platforms, like how often and for how long they visit.” The team emphasized the the importance of considering both natural and artificial features when planning conservation strategies such as Marine Protected Areas.
However, the presence of industrial infrastructure is not without risks for whale sharks. Co-author Dr. Luciana Ferreira of AIMS said, “There are records of fatal interactions between whale sharks and vessels and a considerable portion of the whale shark population at Ningaloo Reef have scars attributed to vessel strikes.” Additionally, she argues, the artificial presence of oil platforms could inadvertently alter natural migration routes and disrupt the connectivity between key feeding and breeding sites. “Having said that, whale sharks are at risk across large areas of their distribution from ship strike and fishing bycatch and entanglement, and we need to do more research to better understand the threats.”
The research was conducted with support from several institutions, including The Australian National University, ECOCEAN, The University of Queensland, and Murdoch University, with funding provided by Santos Ltd and AIMS.
