Whale sharks in popular tourism regions are sustaining most of their injuries from human activity, a new study says.
Nearly 80 per cent of the injuries among whale sharks in Indonesian waters are scars from collisions with boats or fishing platforms.
Researchers tracked 268 whale sharks over 13 years in the Bird’s Head Seascape of West Papua, a global biodiversity hotspot and popular whale shark tourism destination. They found that three-quarters of the sharks had scars or wounds, usually from rubbing against fishing platforms known as bagans or from tour boats.
Most had minor abrasions but almost one in five bore serious injuries like amputations or deep lacerations from propellers.
“Scars and injuries were mainly from anthropogenic causes such as collisions with bagans … and whale shark-watching tour boats,” said Dr Edy Setyawan, the lead conservation scientist at the Elasmobranch Institute Indonesia.
“Relatively harmless minor abrasions were the most common. Serious injuries from natural causes such as predator attacks, or from boat propellers were much less common.”
Whale sharks, the world’s largest fish, are listed as an endangered species by the International Union for Conservation of Nature. Their populations have declined by more than 50 per cent globally over the past 75 years and by as much as 63 per cent in the Indo-Pacific.
Because they take up to 30 years to reach sexual maturity, their populations recover very slowly from threats such as hunting, entanglement and habitat loss.
Most of the whale sharks in Indonesian Papua are juvenile males four to five metres long. They spend more time near the surface and around fishing platforms, frequently gathering around bagans to suck anchovies and other baitfish straight from nets.
“Previous studies from around the world have shown that adult whale sharks, particularly females, 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,” co-author Mochamad Iqbal Herwata Putra of Konservasi Indonesia said.
Nearly half of the sharks were resighted at least once. One individual was recorded 34 times over three years.
Researchers say this high level of residency shows whale sharks should be regarded as valuable tourism assets for local communities.
They warn that as whale shark tourism expands, so too will the risks, unless changes are made to prioritise their safety. They recommend simple modifications to fishing platforms and boats, such as removing sharp edges from outriggers and net frames.
“We aim to work with management authorities of the marine protected areas to develop regulations to require slight modifications to the bagans,” Dr Mark Erdmann, Shark Conservation Director for Re:wild, said. “We believe those changes will greatly reduce scarring of whale sharks in the region.”
The Bird’s Head Seascape has a network of 26 marine protected areas and some of the highest levels of tropical marine biodiversity on the planet.
Researchers argue that protecting whale sharks here is critical both for conservation and for sustaining tourism that supports local livelihoods.
Extreme rain linked to train derailment likelier due to climate change – study
Pakistan floods force mass evacuations as Sikh holy shrine inundated
Europe experienced its worst wildfire season on record this year
India warns Pakistan to expect flooding after opening major dams near the border
Scientists hail major breakthrough in holy grail of renewable energy
FEMA staff warn Trump officials’ actions risk a Katrina-level disaster
