SINGAPORE: Whale sharks are the world’s largest fish, yet the movements and key habitats of these highly migratory creatures largely remain a mystery.
But a decade-long study tracking whale shark movements in the Indo-Pacific region has helped Indonesian researchers uncover migration patterns and feeding sites, as well as better understand the various ways different demographics of whale sharks use the waters.
The study also identified Indonesia as a global stronghold for whale sharks in the Indo-Pacific region, with two locations – Saleh Bay in Sumbawa island, east of Bali, and Cenderawasih Bay in West Papua, some 2,000km away – being year-round habitats for the endangered creatures.
Together with local communities and government partners, national foundation Konservasi Indonesia is working to establish Indonesia’s first whale shark-focused marine protected area in Saleh Bay, which was designated a conservation area by the provincial government in May.
Scientists believe the bay may also serve as a nursery habitat, after the rare discovery of newborn whale sharks in the waters in 2025.
“Our research shows that Indonesia plays a central role in whale shark connectivity across the Indo-Pacific, while also revealing how limited their year-round habitat truly is,” said Mochamad Iqbal Herwata Putra, focal species conservation senior manager at Konservasi Indonesia.
“Through the protection of their ‘childhood home’, we can make sure that important areas for whale sharks can be managed effectively and support the recovery of the population,” added Mochamad Iqbal, who was also the lead author of the study.
Led by Konservasi Indonesia, research non-profit Elasmobranch Institute Indonesia and other partners, researchers tracked 70 whale sharks from 2015 to 2025 via satellite tags, with some whale sharks being tracked for more than two years.
For the study, they collaborated with local fishermen to catch the whale sharks in nets for tagging, as the whale sharks were observed to approach and interact with wooden fishing platforms known as bagan, said Mochamad Iqbal.
Recognisable for the unique patterns on their skin, whale sharks are filter feeders, surviving on a diet of plankton, krill and small fish. More than 60 per cent of the population is found in the Indo-Pacific Ocean.
The study produced one of the largest satellite tag datasets for whale sharks ever studied, tracing their movements across 13 countries.
Edy Setyawan, Elasmobranch Institute Indonesia’s lead conservation scientist, said: “From aggregation sites in the Indonesian archipelago, they travel huge distances, guided by food, currents and environmental cues. Many of these journeys take them into international waters and high seas, where protections are limited.
“That’s where these endangered animals face the biggest dangers from unsustainable fisheries and busy shipping routes.”
As solitary creatures, their movements differ across individuals, explained Mochamad Iqbal. The study found that juvenile males tend to occupy areas with nutrient-rich waters such as coastal areas.
Meanwhile, females and adult males use deeper habitats in the high seas, hunting around areas such as underwater mountains and canyons.
Having such data can better inform conservation management, allowing conservationists to identify habitats specific to a particular demographic and its purpose, such as for migration or foraging, said Mochamad Iqbal.
“Protecting these habitats is critical to maintaining connectivity and sustaining the population. If we want to protect whale sharks, we cannot protect only a particular habitat,” he said.
“If we want to protect the whole population, we need to understand which areas are utilised the most and then prevent threats they face in the area.”
The team’s close ties with local fishermen also allowed them to record Indonesia’s first baby whale shark sighting in Saleh Bay, after they were alerted to the accidental capture of a whale shark measuring around 1.5m long.
Whale sharks can grow up to 12m or longer and are estimated to have an average lifespan of 70 years in the wild. However, individuals less than 1.5m in length are rarely encountered, and the baby whale shark was later estimated to be around four months old.
“I think working with the local community and fishermen is key. They are scientists, in a traditional way, and we can use their local ecological knowledge to improve our modern science,” said Mochamad Iqbal.
Whale sharks serve as indicators of healthy marine environments, and their presence often acts as a natural sign of a productive fishing ground for local fishermen, he added.
The researchers also assisted local tourism operators by sharing tracking data from the study, enabling the community to develop a better understanding of the locations and timings of whale shark sightings, said Mochamad Iqbal.
He added that following the study, Konservasi Indonesia is engaging tourism operators and local communities in the area to build a citizen science programme and increase their involvement in research and conservation.
By establishing a whale shark-focused marine protected area, researchers hope to protect not just the whale sharks, but also their nursery area, which is sensitive to human activity, as well as their food source, he said.
To understand the optimal level of fishing operations in the bay, researchers are currently conducting fish stock assessments to understand fishing pressures in the area.
Mochamad Iqbal said: “As a conservation scientist, I’m very happy to see our research being used for policy and decision-making.
“Knowing that our study does not just stay as a publication and is used to help our earth and the animals makes me feel good.” - The Straits Times/ANN
