Are Shark Sanctuaries Worth It? Evidence Suggests Yes—When Design, Enforcement, and Time Are Aligned
Protection works—but only as part of a system
Shark sanctuaries are often discussed as one of the most direct policy tools for reducing shark exploitation at large spatial scales.
By restricting or prohibiting shark fishing across entire national waters or designated zones, they aim to reduce mortality, stabilize populations, and protect ecological roles that sharks play in marine ecosystems.
But the key question is not only whether sanctuaries are effective in principle—it is what conditions are required for them to deliver measurable conservation outcomes.
This study examines that question through real-world implementation.
What this study actually does
In Shark sanctuaries: a conservation strategy for sharks? (Science), we evaluated early large-scale shark sanctuary designations and their potential to reduce exploitation pressure across national jurisdictions.
The analysis drew on available fisheries data, enforcement capacity indicators, and spatial protection coverage to assess how sanctuary designation translates into ecological and management outcomes.
The work was published in Science and informed by comparative analysis of shark management approaches across multiple regions.
What the study shows
The establishment of shark sanctuaries represents a meaningful shift in how some jurisdictions approach shark conservation.
Across implemented sanctuaries, the key observed outcome is a reduction in targeted shark fishing pressure within designated waters, particularly where enforcement capacity is present and clearly defined.
However, the effectiveness of sanctuaries is not uniform. Outcomes depend on several interacting factors:
Enforcement capacity: Monitoring, compliance, and ability to deter illegal fishing are critical
Spatial scale: Larger sanctuaries tend to provide broader protection but require stronger governance systems
Fisheries displacement: Fishing pressure may shift outside sanctuary boundaries if not managed at a regional scale
Complementary measures: Trade regulations, bycatch controls, and regional agreements strengthen effectiveness
When these elements are aligned, sanctuaries can contribute to meaningful reductions in shark mortality within protected areas.
Why this matters for ocean systems
Shark sanctuaries function as a spatial management tool within broader fisheries systems.
Their importance lies not only in restricting extraction, but in reshaping how human activity interacts with shark populations over space and time.
When effectively implemented, they can:
reduce direct fishing pressure on vulnerable species
protect critical habitats and aggregation areas
support recovery in localized populations
reinforce broader fisheries management objectives
However, sanctuaries are not standalone solutions. Their effectiveness depends on how they integrate into wider governance and enforcement frameworks.
The key insight: protection is not only about designation
One of the central messages from this work is that designation alone does not determine outcomes.
A sanctuary is a spatial policy decision—but its ecological impact depends on how consistently that policy is implemented, monitored, and supported over time.
In practice, this means that:
time is a critical factor in ecological response
enforcement determines real-world effectiveness
and evaluation is necessary to understand whether objectives are being met
