Balancing science, public safety, and conservation through a precautionary lens

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South Africa was the first country in the world to grant full legal protection to the white shark (Carcharodon carcharias). This landmark decision, taken in 1991, was guided by a precautionary approach — recognising the ecological importance of apex predators and their economic value to coastal communities and marine tourism, despite limited data on population status at the time.

More than three decades later, new research has reignited debate around the status of South Africa’s white shark population. At the centre of this discussion is a critical question: are white sharks simply redistributing along the coastline, or is the population in decline? The answer to this question has direct implications for management, conservation policy, and the future of this protected species.

Why This Debate Matters?

At the Oceans Research Institute, long-term datasets, ecosystem-based thinking, and evidence-led decision-making form the foundation of our approach to interpreting population trends. This debate is not academic — it directly influences how conservation measures are implemented, how public safety is managed, and how South Africa meets its national and international biodiversity commitments.

Multiple Lines of Evidence Point Toward Decline

Several independent indicators suggest that South Africa’s white shark population is more likely to be declining than stable:

• Reduced sightings at historically well-studied aggregation sites over the past decade, particularly of large, mature individuals that are essential for reproduction.
• Low genetic diversity and a small effective population size, limiting resilience to additional pressures and environmental change.
• Population simulation modelling indicating that current levels of white shark removals by South Africa’s lethal shark control program — even in isolation — exceed what the population can sustain over time.

Importantly, these indicators emerge from different methodologies and datasets yet converge on the same concern: ongoing losses of white sharks are unlikely to be biologically sustainable.

The Orca Redistribution Hypothesis

A recent study has suggested that white sharks have not declined but instead redistributed eastward along the South African coastline in response to increased predation by orcas (Orcinus orca). Predator–prey interactions are natural processes that play a crucial role in structuring marine ecosystems.

However, attributing long-term population-level changes primarily to orca predation becomes problematic when considered alongside persistent, well-documented human-induced sources of mortality. When considering orca predation, we acknowledge that not all predation events have been recorded. However, the higher the effective level of predation, the more urgently South Africa’s government would need to act to reduce the very high levels of white shark mortality under its control. Redistribution alone does not adequately explain observed genetic patterns, demographic changes, or the sustained absence of mature individuals at multiple aggregation sites.

Anthropogenic Pressures Are Manageable

While natural predation is an inherent component of healthy ecosystems, anthropogenic pressures are subject to policy and management decisions. In South Africa, these include:

• The lethal shark control program, which has removed white sharks from coastal waters for more than 65 years.
• Demersal shark fisheries, which may contribute to both targeted and incidental mortality.

Simulation modelling demonstrates that removals through the lethal shark control program alone are sufficient to drive population decline. When combined with other sources of mortality, the cumulative impact becomes increasingly concerning — particularly for a species with slow growth, late maturity, and low reproductive output.

Balancing Public Safety, Livelihoods, and Conservation

Effective shark management must strike a balance between public safety, community livelihoods, and the conservation of biodiversity. Oceans Research Institute recognises the complexity of this challenge and the need for solutions that are socially and economically informed.

However, continued removal of a threatened and legally protected species raises important questions when credible scientific evidence indicates that current mortality levels are unsustainable. As management strategies evolve globally, non-lethal alternatives and adaptive approaches are increasingly recognised as viable pathways to reduce risk while conserving apex predators.

A Renewed Call for a Precautionary Approach

South Africa’s early protection of white sharks positioned the country as a global leader in shark conservation. Applying the same precautionary principle today, informed by decades of additional data, is consistent with both our conservation legacy and our scientific responsibility.

Reducing anthropogenic sources of white shark mortality represents an actionable step toward safeguarding this population and the ecosystem services it supports. These services extend beyond biodiversity, contributing to healthy marine ecosystems, tourism, and ocean resilience upon which many South Africans depend.

The evidence increasingly suggests that waiting for absolute certainty may come at a cost that both the white shark population and South Africa cannot afford.

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