Disappearance whale sharks are covered with scars, and humans are to blame

More than 60% of Indonesia whale sharks are marked, most of them by boats and fishing platforms.

Scientists say that simple changes in tourist equipment and practices could prevent these injuries and help protect the sweet giants of the ocean.

Whale sharks are faced with steep drop

Whale sharks, the largest living fish speciesare classified as in the process of disappearing on the red list of the IUCN of endangered species. Over the past 75 years, populations have decreased by more than 50% worldwide and up to 63% in the Indo-Pacific region. Because whale sharks take up to 30 years to become sexually ripe, populations can only slowly recover threats such as hunting for fins, meat and oil, loss of habitat and tangle in fishing nets.

Now, an international group of researchers has shown that in the sea landscape of the bird of Western Papua, 62% of whale sharks have scars and injuries of avoidable human causes. They argue that simple interventions could considerably reduce this burden on the local population of these sweet giants.

Boats and Bagans injuries

“We have found that the scars and injuries came mainly from anthropogenic causes, such as collisions with` `Bagans ” – traditional fishing platforms with lifting nets – and shark observation turned boats,” said Dr. Edy Setyawan, main scientist of the conservation of the Elasmobran Indonia Institute and study.

“Relatively harmless minor abrasions were the most common. The serious injuries of natural causes, such as predators’ attacks or boat propellers, were much less common.”

Follow -up of whale sharks over the years

Between 2010 and 2023, Setyawan and his colleagues studied the presence by whale sharks at the Baie de Cenderawasih, Kaimana, Raja Ampat and Fakfak in the seastand for the head of the bird, a region organizing a network of 26 sea zones and a hotspot for the marine megafauna and the tropical marine biodiversity. Each whale shark sports its own unique scheme of white spots and scratches, which allowed scientists to use photos of researchers and scientific citizens to identify each individually. Setyawan et al. also recorded the date and time of each observation, its GPS The contact details, sex and maturity status of the shark, size, behavior and visible injuries.

During this period, they observed a total of 268 unique whale sharks, 98% of which were seen in the bay of Cenderawasih and Kaimana. The observations of whale shark was almost exclusively seen near Bagans, where they generally fed on fish-appliaments such as anchovies, herring and sprats-swimming horizontally or in a vertical head-up position. They were also observed to suck fish directly from Bagans, who have often damaged the nets. Most of the light individuals were juveniles between four and five meters long, while 90% were men.

52.6% of whale sharks were put back at least once, up to 11 years apart. The record holder was a young man who was recorded 34 times over three years.

Of the 206 sharks recorded with injuries or scars, 80.6% presented injuries attributed to causes of human manufacture, while 58.3% suffered injuries that probably come from natural causes (Note: Some people have undergone anthropogenic and natural injuries). Serious lacerations, amputations and evidence of blunt trauma of anthropogenic causes were relatively rare, observed in 17.7% of individuals. However, non -fatal abrasions were common and frequently due to whale sharks rubbing against Bagans or boats.

Missing females and mature giants

But where did women and older and sexually mature people drag? Researchers have a good idea.

“Previous Studies from Around the World Haven that adult Whale Sharks, Especially Female, Prefer the Deep Ocean where they feed on prey like Krill and Schooling Fish, While The Younger Males Stay Closer to Shore in Shallow, Plankton-Rich Waters that Help Them Grow Quickly, “Said Co-Author Mochamad Iqbal Herwata Putra, a Senior Manager at the Focal Species Conservation Program of the National Foundation Konservasi Indonesia.

“Our own satellite monitoring data also shows that women and adults frequently use features on the high seas such as canyons and submarines.”

Growing tourism, growing risks

“Whale sharks in Cenderawasih Bay and Triton Bay (Kaimana) had high rates of residence and recovery, indicating that they should be considered as precious tourist assets for local communities and governments,” said Dr. Mark Erdmann, the last author and director of the study of the study of the study for Re: Wild.

Given that the majority of the observations of whale sharks took place in Bagans, at a time when whale shark tourism develops, researchers expect the risk of injury of bagans and boats to increase in the future – unless simple measures are taken to protect the whale sharks.

“We aim to work with the protected marine areas management authorities to develop regulations to require slight modifications for bagans, including the abolition of the lively edges of boats and net executives.

Reference: “Overview of demographic and residence models of the population of photo-identified whales Rhincodon Typus In The Bird’s Head Seascape, Indonesia “by Edy Setyawan, Abdy W. Hasan, Yance Malaiholo, Abraham B. Sianipar, Ronald Mambrarasar, Mark Meekan, Bronwyn M. Gillanders, Ben d’Antonio, Mochamad Ih Putra and Mark V. Erdmann, July 9 2025, July 9, 2025, July 9, 2025, July 9, 2025, July 9, 2025 Borders in marine science.
Two: 10.3389 / FMARS.2025.1607027

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