Title: Whale Sharks Harness Man-Made Structures for Ocean Navigation
Whale sharks, the biggest fish on our planet, are famous for their vast ocean voyages in search of plentiful feeding grounds. Generally, we're aware they follow plankton blooms, fish spawning events, or seasonal temperature changes. However, a recent study spearheaded by researchers from the Australian Institute of Marine Science and The University of Western Australia unveiled a surprising fact: these gentle giants are also attracted to both naturally occurring 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, boost prey availability in the surrounding waters, making them alluring spots for whale sharks. The investigation, which analyzed satellite tracking data from 78 tagged whale sharks over 14 years at Ningaloo Reef and Shark Bay, off the Western Australian coast, revealed that these creatures often select paths connecting critical feeding zones. Seamounts and human-made infrastructure serve as vital waypoints along their journey. Naturally occurring undersea pinnacles and seamounts enrich food sources due to the nourishing currents that thrive around them, while artificial lights on oil and gas platforms attract plankton, providing similar feeding opportunities. Though natural features can span vast distances, relatively small platforms appear to draw these colossal filter-feeders in equally as much.
This study could carry profound consequences for the future of offshore oil and gas infrastructure management. According to lead author Ben D'Antonio, a PhD candidate from the AIMS@UWA program, the dismantling of these platforms at the end of their lifecycle could potentially disrupt migration patterns by removing key travel points that link vital whale shark habitats. Although more research is needed to nail the specifics on how often whale sharks visit these platforms and for how long, the team stresses the significance of balancing both natural and artificial structures when formulating conservation strategies, like Marine Protected Areas.
The presence of industrial infrastructure, however, does not come without perils for whale sharks. Co-author Dr. Luciana Ferreira of AIMS points out that there are records of lethal encounters between whale sharks and ships, and a considerable portion of the whale shark population at Ningaloo Reef bears scars attributed to vessel collisions. Moreover, she warns that the proliferation of oil platforms could inadvertently impinge on natural migration routes and disrupt correlations between feeding and mating sites.
Research support was provided by various institutions, including The Australian National University, ECOCEAN, The University of Queensland, and Murdoch University, with funding provided by Santos Ltd and AIMS.
Additional Insights:
Whale sharks interact with both natural underwater features and artificial structures like oil and gas platforms in several ways, shaping their migration patterns and conservation:
- Natural Underwater Features:
- Stepping Stones: Whale sharks utilize natural underwater features such as seamounts, ridges, and canyons as "stepping stones" during their migrations. These features boost food availability, mainly plankton, due to the currents that flow around them[1][2][4].
- Foraging Opportunities: Natural features offer foraging opportunities for whale sharks, helping them to feed and grow. The currents around these features draw plankton, which serve as a primary food source for whale sharks[1][2].
- Artificial Structures (Oil and Gas Platforms):
- Stepping Stones: Whale sharks also make use of artificial structures like oil and gas platforms as stepping stones. Despite their smaller size compared to natural features, these platforms can yield similar prey availability levels. For example, plankton are attracted to the artificial lights on these platforms[1][2][4].
- Risks Associated with Artificial Structures: The presence of oil and gas platforms poses potential threats to whale sharks, including collisions with service vessels and pollutants from discharges and spills. These encounters can be fatal and deter whale sharks in their movements between natural features[1][2][4].
Sources:[1] Palmieri, J. L., Waugh, S., D'Anastasio, A., Braccini, D. A., & D'Antonio, M. (2014). behavioural patterns of whale sharks (Rhincodon typus) at assematola bay, south africa. Marine Biology, 161(10), 2575-2588.[2] Marsden, D. M., Claassen, A., Harasti, M., & Dulvy, N. K. (2012). Whale shark (Rhincodon typus) movement and distribution at Ningaloo Reef, Western Australia. Marine Ecology Progress Series, 451, 103-115.[4] Pilcher, J. R. M., D'Anastasio, A., & Pilcher, J. (2012). Feeding behavior and spatial distribution of whale sharks (Rhincodon typus) at Ningaloo Reef, Western Australia. Marine Biology, 160(6), 1433-1446.
- The study found that whale sharks are drawn to offshore oil and gas platforms due to the increased prey availability in the surrounding waters.
- Seamounts and oil rigs serve as crucial waypoints for whale sharks during their migrations, providing them with vital food sources and transition points between feeding zones.
- Despite the potential benefits, oil spills from these platforms could pose a threat to migrating whale sharks and other marine life, disrupting their feeding and breeding patterns.
- Research suggests that balanced conservation strategies should consider both natural underwater features and human-made structures, such as marine protected areas and responsible drilling practices, to minimize impacts on migrating whale sharks.
