What Makes a Shark Sanctuary? It Depends on Design, Enforcement, and Evaluation
Shark sanctuaries are not a single policy—they are a spectrum of protection
Shark sanctuaries have become one of the most visible global responses to declining shark populations.
At their core, they aim to reduce shark mortality by restricting commercial shark fishing and, in many cases, banning the export of shark products across large ocean areas—often entire Exclusive Economic Zones.
But while the idea is simple, the reality is not.
A “shark sanctuary” is not one standardized tool. It is a set of regulations that can vary widely in scope, strength, and enforceability—and those differences determine whether it meaningfully protects sharks.
What this study actually does
In “A global overview of shark sanctuary regulations and their impact on shark fisheries” (Marine Policy), we reviewed 11 shark sanctuaries globally, covering roughly 3% of the world’s ocean area.
We examined how these sanctuaries are structured, what regulations they include, and how they intersect with known patterns of shark fisheries and trade.
The goal was not just to document where sanctuaries exist, but to understand what they actually do in practice—and where their design may limit conservation outcomes.
What we found across shark sanctuaries
Across the 11 sanctuaries reviewed, a few consistent patterns emerged.
Most shark sanctuaries include bans on:
commercial shark fishing
retention or landing of sharks
export of shark products
In some cases, they also include provisions that support tourism or non-extractive uses of sharks, reinforcing their economic value in coastal systems.
Where these measures are implemented and enforced, they can reduce direct targeted shark mortality within sanctuary boundaries.
However, the structure of these policies varies significantly between jurisdictions, and this variation matters.
The key limitation: bycatch is largely unaddressed
One of the most important findings is that while shark sanctuaries often focus on targeted shark fisheries, they are far less explicit about bycatch reduction.
This matters because:
sharks are frequently caught incidentally in other fisheries
bycatch can represent a substantial source of mortality
banning targeted fishing alone does not eliminate indirect capture
In many sanctuaries, bycatch remains the main pathway of shark mortality.
As a result, protection can be incomplete even when regulations appear strong on paper.
Why design alone is not enough
Another consistent finding is that sanctuary effectiveness is strongly shaped by what happens after designation.
Three factors determine whether protection translates into real-world outcomes:
1. Enforcement: Without monitoring and compliance capacity, regulations are difficult to implement consistently.
2. Baseline data: Many sanctuaries were created without clear reference points for shark abundance or fishing pressure.
3. Evaluation frameworks: Few sanctuaries define what success looks like—or how it should be measured over time.
This creates a gap between policy intention and ecological outcome.
What the data suggest about global impact
Historical catch data indicate that shark sanctuaries currently represent a relatively small proportion of global shark mortality.
In some cases, sanctuaries were implemented in regions where commercial shark fishing was already limited, meaning their immediate global impact on total shark catch is constrained.
However, this does not diminish their importance.
In several jurisdictions, sanctuaries likely prevented the expansion of commercial shark fisheries and reduced future exploitation pressure—an important form of preventative conservation.
The central issue: we rarely measure whether sanctuaries work
A consistent challenge across all sanctuaries reviewed is the lack of structured evaluation.
Once designated, sanctuaries are often assumed to be effective—but without:
consistent monitoring
baseline ecological data
or clear performance indicators
it becomes difficult to determine whether they are achieving their intended goals.
This is especially true for shark populations, where movement patterns, life histories, and multi-jurisdictional ranges complicate simple before-and-after assessments.
What changes now
This work highlights a clear next step for shark conservation policy:
Shark sanctuaries need to evolve from static designations into evaluated management systems.
That means integrating:
explicit conservation objectives
bycatch-inclusive regulations
long-term monitoring programs
and transparent performance metrics
