Whale sharks use offshore oil rigs as food stops during migration, harming conservation efforts

Massive whale sharks, the gentle giants of the ocean, are engaging in unexpected behavior. According to a new study, whale sharks use oil platforms as migratory stopover sites during their expansive journeys across the globe.

These spotted behemoths don’t just randomly cruise the seas – they follow a network of natural and human-made structures that dot their underwater highways.

These observations come from a long-term tracking study conducted by Ben D’Antonio and his colleagues at the Australian Institute of Marine Science (AIMS) and The University of Western Australia (UWA).

The findings paint a fascinating picture of how these enormous fish navigate the vast expanses of our oceans.

Tracking whale sharks across the ocean

The study involved analyzing satellite tracking data from 78 whale sharks over a span of 14 years. The researchers focused on whale sharks that had been tagged at Ningaloo Reef and Shark Bay – two critical habitats along the Western Australian coast.

According to lead author Ben D’Antonio, a Ph.D. candidate from the AIMS@UWA program, the study provides crucial insights into how these massive creatures navigate the ocean.

“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,” D’Antonio said.

The researchers found that whale sharks use natural underwater formations, such as seamounts, pinnacles, and canyons as navigational aids.

These structures, shaped by ocean currents, act as hotspots for plankton and other small organisms, which provide a reliable food source for the filter-feeding giants.

“Whale sharks travel huge distances across the oceans, and our study illustrates that they tend to use undersea pinnacles and seamounts as stepping stones on these journeys because the currents that flow around these features help to enhance food availability like plankton,” said D’Antonio.

Interestingly, the researchers also found that artificial structures, such as offshore oil and gas platforms, may play a similar role in facilitating whale shark migration.

Whale sharks like oil and gas platforms

While seamounts and pinnacles can span tens of kilometers, oil and gas platforms are relatively small. Yet, they seem to offer a comparable level of food availability.

Researchers believe this may be due to the way industrial infrastructure affects surrounding marine ecosystems.

“The same is true for the industrial infrastructure found off the north-west coast of Australia,” D’Antonio explained.

There is evidence, for example, that plankton are attracted by the artificial lights on these platforms. This discovery suggests that oil and gas platforms may unintentionally benefit marine life by attracting prey species.

However, the role of oil and gas platforms as migratory stepping stones also raises new questions about how their eventual removal could affect whale shark movement patterns.

Impact of oil platform removal

As oil and gas platforms reach the end of their operational lives, many are scheduled for decommissioning.

The study’s findings suggest that removing these structures could disrupt whale shark migration.

“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,” D’Antonio said.

Understanding the extent to which whale sharks depend on these artificial structures is now a priority.

Why does any of this matter?

Researchers need to determine how frequently the sharks visit platforms and whether they rely on them for sustenance or merely use them as occasional stopovers.

“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,” noted D’Antonio.

These insights are crucial for conservation and management strategies, particularly when planning marine protected areas (MPAs) and making decisions about decommissioning offshore infrastructures.

Policymakers must carefully weigh the ecological consequences before dismantling platforms that may serve an unexpected but important role in whale shark migration.

Balancing conservation and risks

While the presence of oil and gas platforms may provide benefits for whale sharks, they also introduce significant risks. Ship strikes from service vessels are a major concern, particularly in areas with heavy industrial activity.

AIMS scientist and co-author Dr. Luciana Ferreira pointed out the dangers posed by vessel interactions.

“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,” she said.

Whale sharks, offshore oil, and pollution

Pollution is another pressing issue. Discharges, spills, and other contaminants associated with industrial operations can pose serious threats to marine life.

Even subtle environmental changes caused by industrial infrastructure may have unintended consequences for whale shark behavior.

“The presence of the platforms may also have indirect implications by altering migration patterns and disrupting the movements of whale sharks between natural features,” explained Dr. Ferreira.

Despite these concerns, whale sharks face threats across their entire distribution. Fishing bycatch, entanglement, and ship strikes are all significant dangers that affect populations globally.

To protect whale sharks effectively, conservationists must take a holistic approach that accounts for both natural and artificial influences on their movements.

Need for further research

This study highlights the complexity of whale shark conservation. While natural features remain the primary drivers of migration, artificial structures appear to play a growing role in shaping their movement patterns.

Experts must now investigate whether these structures act as temporary refuges, long-term feeding grounds, or accidental hazards.

More broadly, the study highlights the importance of integrating industrial considerations into marine conservation planning. With careful management, it may be possible to mitigate risks while preserving the unexpected benefits that artificial structures provide.

As decisions about decommissioning offshore platforms loom, scientists and policymakers must work together to ensure that conservation efforts align with the realities of an ever-changing marine environment.

The future of whale sharks depends on understanding how both natural and human-made factors, such as oil and gas platforms, shape their world – and ensuring that their migratory pathways remain intact for generations to come.

The study is published in the journal Diversity and Distributions.

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