In June 2026, a decade-long satellite tracking effort across Indonesian waters delivered the most detailed map ever assembled of whale shark movements in the Indo-Pacific. Researchers fitted 70 whale sharks with satellite tags at four aggregation sites between 2015 and 2025, and their findings, published in Frontiers in Marine Science, single out two Indonesian bays as unmatched strongholds for the world’s largest fish: Saleh Bay, off the island of Sumbawa, and Cenderawasih Bay, tucked inside Papua’s Bird’s Head Seascape. No other known site on Earth holds whale sharks in every month of the year the way these two do.
The same tracking data revealed that tagged sharks routinely crossed into the exclusive economic zones of 12 other nations, tying roughly 60 percent of the global whale shark population to a 13-country corridor. For a species listed as Endangered on the IUCN Red List and protected under CITES Appendix II, that cross-border reality complicates conservation in ways no single government can solve alone.
Two bays, twelve months of sharks
Whale sharks gather in predictable numbers at dozens of sites worldwide, from Mexico’s Caribbean coast to Mozambique’s Tofo Beach. But most of those aggregations are seasonal, driven by plankton blooms or spawning events that last weeks or months before the sharks move on. Saleh Bay and Cenderawasih Bay break that pattern.
In Cenderawasih Bay, the evidence runs especially deep. A separate photo-identification study in Frontiers in Marine Science compiled thousands of individual encounters and confirmed sightings spread across all 12 months, wet season and dry season alike. The bay’s semi-enclosed geography shields it from the strongest monsoon swells, creating unusually stable conditions that appear to support genuine residency rather than a revolving door of transient visitors.
Within the bay, the Kwatisore area inside Cenderawasih Bay National Park has become a focal point. Research published in the Jurnal Sumberdaya Akuatik Indopasifik documented whale sharks congregating around bagan, the traditional lift-net fishing platforms used by local fishermen. Small fish spilling from the nets create a reliable, concentrated food source, and the sharks have learned to exploit it. That predictability has turned Kwatisore into both a research hub and a growing marine tourism destination, though published studies have not yet quantified visitor traffic or assessed whether boat activity is changing shark behavior.
Saleh Bay tells a different and potentially more consequential story. Field teams have repeatedly encountered neonatal whale sharks there, animals so small they still carry visible umbilical scars. In a study published in the journal Diversity, researchers described these newborns and argued that the bay may function as a nursery ground, a place where whale sharks are not just feeding but being born and spending their earliest, most vulnerable life stages. If that hypothesis holds, Saleh Bay would rank as something rarer than a gathering spot: a source population that seeds whale shark aggregations across multiple countries.
A 13-country problem
The satellite tracks paint a picture of animals that respect no borders. Tagged whale sharks leaving Indonesian waters entered the jurisdictions of 12 other nations, though the published study does not list those countries individually or break down how much time sharks spent in each. Given Indonesia’s position at the center of the Coral Triangle, the likely candidates include the Philippines, Malaysia, Australia, Papua New Guinea, Timor-Leste, and several Pacific island states, all of which share overlapping waters with known whale shark habitat.
That geographic spread matters because legal protections vary sharply from one jurisdiction to the next. Indonesia has maintained full national protection for whale sharks since a 2013 ministerial decree, and Cenderawasih Bay carries formal national park status. But a legal designation on paper does not automatically translate to safety at sea. The published research includes no patrol logs, violation records, or compliance data from either bay. For Saleh Bay, there are no primary records in the cited literature quantifying current fishing pressure or vessel interactions. Readers should treat “protected” as a legal fact, not a guaranteed outcome, especially across vast and remote marine areas where enforcement boats are scarce.
Outside Indonesian waters, the picture grows murkier. Some neighboring nations have their own whale shark protections; others do not. Without a country-by-country breakdown from the tracking study, it is impossible to say how many of the 13 jurisdictions leave migrating sharks exposed to gillnets, ship strikes, or targeted fishing. That gap is not just an academic inconvenience. It is the central policy question the data raise: if 60 percent of the world’s whale sharks depend on a corridor spanning 13 countries, conservation plans built around a single nation’s parks and regulations will always be incomplete.
What the numbers can and cannot tell us
The 60 percent figure deserves careful reading. It comes from a robust dataset by whale shark research standards: 70 individually tagged animals tracked over 10 years, a sample size that few studies of large, pelagic species can match. But whale shark population estimates remain uncertain. The species’ total global numbers are not precisely known, and the 70-shark sample, while large for this field, cannot capture every subpopulation worldwide. The study’s authors derived their estimate from the movement patterns and site fidelity of tagged individuals, and it should be understood as a well-supported inference from the sampled population rather than a census.
The nursery claim for Saleh Bay rests on similarly solid but still incomplete ground. Documenting neonatal sharks with fresh umbilical scars is direct, primary field evidence, and it is rare. Whale shark pupping has almost never been observed or confirmed at any site globally. But occurrence is not the same as population-level confirmation. Researchers have not yet conducted genetic sampling to link the neonates to local adults, tracked juvenile cohorts over multiple years, or modeled how many recruits Saleh Bay contributes to the wider population. Until that work is done, the nursery hypothesis remains compelling but provisional.
There is also a broader caveat worth noting. The claim that Saleh Bay and Cenderawasih Bay are the “only two places on Earth” with year-round whale shark presence is the strongest statement the Indonesian data support, but a separate global residency analysis in Frontiers in Marine Science found that some aggregation sites outside Indonesia also show sightings in all 12 months, typically at lower densities or with sharper seasonal peaks. The Indonesian bays appear to have the most robust and consistent records, but characterizing them as the sole year-round locations reflects the depth of monitoring there as much as the biology. Less-studied sites elsewhere may eventually join the list as research catches up.
What comes next for the sharks
For conservation planners, the practical implications are clear even where the science is still filling in gaps. Indonesia’s two bays are demonstrably central to the life history of a globally endangered species. Saleh Bay’s possible role as a nursery, if confirmed, would make it one of the most important single sites for whale shark survival anywhere on Earth. Cenderawasih Bay’s year-round residency and its entanglement with local fishing and tourism economies demand management strategies that balance human livelihoods with shark welfare.
But the satellite tracks also show that protecting these bays alone is not enough. The sharks leave. They cross into waters governed by different laws, different enforcement capacities, and different political priorities. The 13-nation footprint revealed by a decade of tagging is, at its core, an argument for regional cooperation: bilateral agreements, harmonized fishing regulations, and shared monitoring systems that follow the animals rather than stopping at maritime boundaries.
The data now exist to build that framework. Whether the political will follows is a different question entirely.
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*This article was researched with the help of AI, with human editors creating the final content.
