The whale shark (Rhincodon typus) is the largest fish ever known, facing a real risk of extinction. In recent years the global population has declined, yet scientists have not pinpointed a single cause. An international team spanning 50 institutions and universities tracked whale sharks and commercial ships worldwide to uncover the threats. Their findings show that shipping incidents cause hundreds of deaths and pose a grave danger to the species’ future.
Research led by the Marine Biological Association and the University of Southampton in the United Kingdom revealed that fatal collisions with large vessels have been significantly underestimated and may drive population declines. Over the past eight decades the species has already fallen by more than 50 percent.
Whale sharks can reach up to 20 meters in length and weigh more than 34 tons. They spend substantial time at the surface and gather in coastal zones, which increases the likelihood of encounters with ships. This connection prompted researchers to test the hypothesis that ship strikes contribute to high mortality rates among whale sharks.
The study, published in the Proceedings of the National Academy of Sciences, aimed to quantify this threat, identify high-risk areas, and anticipate potential collisions. Satellite-tracked movements for 348 whale sharks were shared with the Global Shark Movement Project, led by MBA researchers, to map overlap with global shipping lanes.
Regulate the speed of ships
The team highlighted critical overlap points where whale sharks intersect with cargo ships, oil tankers, cruise vessels, and large fishing boats. They found that more than 90 percent of whale shark movements coincide with heavy shipping activity.
Satellite tracking also showed that signals from tagged whale sharks often end up in busy shipping lanes sooner than expected. The researchers concluded that many transmissions stop because whale sharks are struck by large ships, sink, and disappear from the tracking network.
Dr. Freya Womersley emphasized that the shipping industry, essential for global trade and access to a variety of diary products, could contribute to the decline of whale sharks, a crucial species in ocean ecosystems. Southampton researchers led the investigation.
Maritime transport moves more than 90 percent of global commerce, a reality that shapes market access and freight costs. The study authors call for monitoring collisions, setting speed limits in identified risk zones, and implementing local safeguards to lessen the threat of fatal collisions.
Professor David Sims of the University of Southampton and founder of the Global Shark Movement Project noted that most tagged whale sharks travel along major routes and then descend toward the deep seafloor. The ocean lies hundreds of meters below the surface.
harmless to humans
It is disheartening that many whale shark deaths have occurred in ways that could have been prevented through better action. At present there are no international regulations specifically protecting whale sharks from ship strikes.
The researchers issue a clear warning: the whale shark faces an uncertain future unless swift steps are taken. They hope their findings will inform management decisions to conserve the species and prevent further population declines.
The authors advocate dedicating time and energy to developing strategies that shield this endangered species from commercial transport. Doing so could ensure that the world’s largest fish endures future challenges such as shifts in ocean climate and habitat pressures.
The report also notes that similar hidden mortality could occur for other marine megafauna, including sunfish, sea turtles such as the leatherback, and large whales. These species face additional risks from habitat loss, climate change, accidental net entanglement, and poaching for meat, fins, and oil.
Despite its size, the whale shark remains peaceful and poses no threat to humans. It feeds on zooplankton, helps regulate plankton populations, and plays a vital role in marine food webs and healthy ocean ecosystems.
Citation: Proceedings of the National Academy of Sciences.
…..
The environment department can be consulted for additional information.