In May 2024, a surprising discovery by local Indonesian fishers reignited an extraordinary story. The long-distance migration of a great white shark (Carcharodon carcharias) tagged more than a decade earlier off the coast of South Africa. What began as a routine satellite-tracking project has evolved into a groundbreaking case study, that is reshaping scientific understanding of shark movements across oceans, and sparking renewed debate about conservation challenges on opposite sides of the Indian Ocean.
The remarkable case was first detailed in the peer-reviewed study Transoceanic dispersal and connectivity of a white shark (Carcharodon carcharias) between southern Africa and Southeast Asia, published in Wildlife Research. Later, Mongabay brought the story into public view with an in-depth report underlining the shark’s incredible 37,178-kilometer journey from South Africa to Southeast Asia. Together, the two accounts offer the first documented evidence of connectivity between great white shark populations in these distant regions.
From Gansbaai to the Tropics
On May 9, 2012, researchers working in Gansbaai, South Africa—a global hotspot for white shark research—tagged a 390-centimeter female with a SPOT-258 satellite transmitter. Nicknamed “Alisha” by some in the scientific community, the shark initially lingered near the tagging site, remaining within about 150 kilometers of the coast for roughly five months.
Then the shark began a journey that astonished scientists. Over the next four and a half years, Alisha traversed the western Indian Ocean, moving past the exclusive economic zones of Mozambique and Madagascar, before eventually reaching the waters of Indonesia.
By the time she was accidentally caught by fishers near Sumba, eastern Indonesia, in November 2016, Alisha had grown to 473 centimeters in length, adding 83 cm at an average growth rate of about 18.4 cm per year. Tragically, she was misidentified at the time as a shortfin mako shark (Isurus paucus) and was landed for local consumption.
Although her life ended prematurely, her satellite tag—initially withheld by the fishers out of fear of legal consequences—was eventually handed over in 2024 after conservation groups offered an incentive. That decision unlocked years of data and allowed scientists to reconstruct the shark’s extraordinary transoceanic voyage.
The Significance of the Journey
For marine biologists, the recovery of this data represents a watershed moment in shark science.
Lead researcher Dylan Irion emphasized how rare such a case is. “You never really see a shark moving that far,” he told Mongabay, noting that while previous tags had revealed long-distance movements—such as the so-called “P12” shark that traveled from South Africa to Australia—Alisha’s journey extended the known limits of white shark dispersal.
The discovery is important not only because of the distance involved but also because it reveals connectivity between two regions previously considered distinct in terms of shark populations. This suggests that the Indian Ocean is far more permeable to white sharks than previously thought, challenging assumptions about population structure.
Yet experts caution against over-interpreting the findings. Sara Andreotti, a postdoctoral researcher at Stellenbosch University who was not involved in the study, pointed out that migration alone does not prove interbreeding between populations. “The fact that they traveled tells us a great deal about their migratory routes, but even that does not necessarily mean they travel there to breed,” she explained.
Her remarks highlight a critical question that remains unanswered: whether these rare long-distance journeys contribute to genetic exchange between distant populations or simply represent individual exploratory events.
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Tracking the Unseen
The case underscores both the power and the limitations of satellite tagging. Between 2012 and 2016, the SPOT-258 transmitter collected invaluable location data, allowing researchers to reconstruct a detailed track of Alisha’s movements. Complementary photo identification efforts in South Africa helped verify her identity during the early stages of the journey.
But tagging projects remain expensive and logistically challenging, and very few white sharks are ever tracked across such timescales. The recovery of the tag by Project Hiu—a conservation initiative based in Lombok, Indonesia—proved decisive. Without local cooperation, the data might never have resurfaced.
This collaboration highlights another lesson from the case, that science depends not only on advanced technology but also on trust and partnership with coastal communities. Initially reluctant to surrender the device, the fishers only came forward years later when reassured that doing so would not bring legal repercussions.
Conservation Challenges on Two Fronts
The scientific breakthrough comes against a backdrop of escalating threats to white sharks in both South Africa and Indonesia.
In South Africa, once considered a stronghold for the species, populations have declined sharply in recent years. Experts cite multiple pressures: targeted fishing, shark nets and drumlines deployed for bather protection, and incidental bycatch in commercial fisheries.
Indonesia presents a different but equally urgent challenge. Here, sharks are not merely incidental bycatch but often direct targets for fishers, who harvest them for meat and fins. White sharks are so rare in Indonesian waters that they seldom appear in official records. The misidentification of Alisha as a mako illustrates how gaps in fishery identification guides and limited training for inspectors complicate conservation efforts.
These shortcomings in species recognition mean that white sharks may be caught more often than the data suggest, their presence hidden within mislabeled catch reports.
Both Irion and Andreotti agree that the case is scientifically significant, though for different reasons.
Irion views the migration as unprecedented and invaluable for understanding how wide-ranging white sharks can be. The sheer scale of Alisha’s journey, he argues, opens new avenues of inquiry into habitat use, navigation, and survival strategies across ocean basins.
Andreotti, however, stresses the need for restraint in interpreting the data. While acknowledging the importance of documenting such a journey, she warns against assuming it automatically translates into connectivity at the population level. The ultimate question—whether these sharks interbreed across regions—remains unresolved.
Their perspectives illustrate a balance between excitement and caution, hallmarks of responsible science.
Implications for Global Conservation Policy
At a policy level, Alisha’s journey reinforces the importance of multinational cooperation in shark conservation. Migratory species like white sharks do not respect national boundaries, traversing jurisdictions that often differ widely in terms of regulation and enforcement.
The Convention on Migratory Species (CMS) already lists the great white shark in its appendices, urging international collaboration. But as this case shows, effective conservation requires not just treaties but also practical mechanisms for data sharing, community engagement, and enforcement at sea.
The role of local initiatives such as Project Hiu demonstrates how community-based conservation can complement global frameworks. By building trust with fishers, the project facilitated the recovery of a lost scientific record, turning what might have been a forgotten tag into a breakthrough discovery.
While the scientific community celebrates the insights gained from Alisha’s journey, the story is tinged with tragedy. Her premature death underscores the fragility of the very creatures scientists seek to understand.
White sharks are apex predators critical to marine ecosystems, but they are also highly vulnerable. Their slow reproductive rates, long gestation periods, and delayed maturity make them especially susceptible to population decline.
Alisha’s story is therefore both an inspiration and a warning: a reminder of the resilience of sharks to undertake epic journeys, and of their vulnerability to human activity that can cut those journeys short.
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Looking Ahead
Scientists now face the challenge of building on this rare case. More tagging studies, expanded photo identification databases, and improved fishery monitoring will be needed to determine whether Alisha’s journey was an outlier or part of a broader but overlooked pattern.
Equally important will be efforts to improve training and resources for fishery inspectors in regions like Indonesia, ensuring that white sharks and other threatened species are correctly identified in landing data. Without accurate records, policymakers lack the evidence needed to implement effective protections.
Ultimately, Alisha’s story offers a powerful narrative for both science and conservation. It shows that even in a world where satellite tracking and genetic analysis are possible, chance encounters and human choices—whether a fisher decides to surrender a tag, or a local community agrees to collaborate—can shape the course of discovery.
The recovery of a single satellite tag has rewritten part of the scientific record on white shark movements, revealing that individuals can traverse the Indian Ocean from South Africa to Southeast Asia. For Dylan Irion, the case proves that sharks are capable of feats beyond what scientists had imagined. For Sara Andreotti, it is a reminder to temper enthusiasm with caution, recognizing that much remains unknown about the genetic and ecological consequences of such journeys.
Together, their voices capture the dual message of Alisha’s odyssey: awe at the capacity of a top predator to connect distant seas, and humility before the limits of current knowledge.
If conservationists, scientists, and communities can heed both lessons, Alisha’s final journey may yet help ensure that future generations of white sharks can undertake their own epic voyages—unseen but vital threads stitching together the world’s oceans. (Sulung Prasetyo)
