What Is Shark Culling and Why Is It So Controversial?

Shark culling refers to the deliberate killing or removal of sharks from coastal waters to reduce the risk of shark bites on swimmers, surfers, and divers. It has been practiced for decades in Australia and South Africa using underwater nets and baited hooks, and the controversy comes down to a collision between two things people care deeply about: human safety at the beach and the health of marine ecosystems. The evidence on both sides is more complicated than either supporters or critics tend to acknowledge, which is part of why the debate stays heated.

How Shark Culling Actually Works

The term “shark culling” is a broad label, and the specific gear matters a lot for understanding the debate. The two main tools are shark nets (also called mesh nets or gill nets) and drumlines, and they work in fundamentally different ways.

Shark nets are large panels of mesh set near the seabed at popular beaches. In Queensland’s Shark Control Program, for example, surface nets are constructed from three panels joined end to end, creating a barrier roughly 186 meters long with a six-meter drop, anchored to the seabed with heavy anchors and marked with floats.¹ A common misconception is that these nets form a wall between swimmers and open ocean. They do not. The nets are set parallel to the beach but do not span the full width of the swimming area. Sharks can swim around, over, or under them. The nets work not by blocking sharks but by catching and removing them from the local population over time.

Drumlines are the other primary tool. A drumline is a single large baited hook suspended from a buoy, anchored to the seafloor. The hook hangs at least two meters off the bottom and is typically baited with sea mullet or shark flesh.¹ When a shark takes the bait, it is hooked and held in place until a contractor arrives to deal with it. In traditional programs, the shark is killed. In newer programs using SMART drumlines (more on those below), the shark is tagged and released.

Drumlines were originally tested in South Africa’s KwaZulu-Natal region as an alternative to gill nets because they showed greater selectivity for sharks and a reduced catch of dolphins, turtles, rays, and bony fish.² The three species most often targeted by these programs are bull sharks, tiger sharks, and white sharks, the species responsible for the majority of serious bites on humans.

Where and When Shark Culling Began

Large-scale shark control programs have operated at popular beaches in New South Wales and Queensland, Australia, and in KwaZulu-Natal, South Africa, for decades.³ KwaZulu-Natal’s nets have been in place since 1952. New South Wales began its shark meshing program in 1937, making it one of the oldest in the world. Queensland introduced nets and drumlines later, gradually expanding coverage to beaches along its coast.

These programs were born in an era when shark bites carried extremely high fatality rates and there were few other options. The basic logic was straightforward: fewer large sharks near the beach means fewer encounters with people. Over the decades, however, the context has changed. Emergency medical response is faster, beach patrols are more sophisticated, and our understanding of marine ecology has deepened. All of those shifts feed into the controversy over whether traditional culling still makes sense.

Does It Actually Reduce Shark Bites?

This is the central practical question, and the answer is less clean than proponents often suggest. The rate of shark bites has indeed declined in areas with long-running control programs, but attributing that decline specifically to the nets and drumlines is harder than it sounds. A detailed analysis of New South Wales’s 80-year shark meshing program found that total shark numbers and populations of the three key target species have dropped over the program’s lifetime, and the incidence of shark bites has declined since the program’s introduction.⁴

But that same analysis raised two important caveats. First, key factors that also influence bite rates are frequently overlooked: changing cultures of beach use and ocean recreation, advances in beach patrols, and improvements in emergency and medical response. Second, the proportion of bites that prove fatal has dropped significantly in recent decades for reasons that have nothing to do with nets, mainly because medical care has improved.⁴ In other words, the decline in shark bite incidents is real, but multiple social and environmental factors contribute to that outcome. Crediting nets alone overstates their role.

This distinction matters because it shapes how governments weigh costs and benefits. If nets are responsible for most of the safety improvement, removing them seems risky. If they contribute only a portion of the improvement alongside lifeguards, helicopters, medical response, and public education, then the ecological cost of nets looks harder to justify.

The Bycatch Problem

The ecological case against shark culling starts with bycatch. Shark nets are not selective. They catch dolphins, sea turtles, rays, and various bony fish along with the target shark species.² Many of these animals drown or die from stress before contractors check the gear. Over decades of operation, the cumulative toll on non-target marine life has been substantial, and some of the species caught are themselves threatened or endangered.

Even drumlines, which are more selective than nets, catch non-target species. A SMART drumline trial on the New South Wales coast caught 300 animals across 16 species, including 11 shark species. Target species (white, tiger, and bull sharks) made up about 70% of the catch, but the remaining 30% included dusky whalers, grey nurse sharks, smooth hammerheads, common blacktips, loggerhead turtles, green turtles, a leatherback turtle, a black marlin, and a manta ray.⁵ Grey nurse sharks, for instance, are critically endangered in eastern Australia, and every accidental capture matters for that population.

The silver lining for SMART drumlines is that most animals survive. In that same trial, 97% were released alive and in good condition. The nine animals that died during capture were mostly smaller species: common blacktips, smooth hammerheads, a dusky whaler, and one white shark.⁵ A separate trial in Réunion using SMART drumlines found that about 87% of caught animals were retrieved alive, though survival varied sharply by species. Giant trevally, scalloped hammerheads, and small carcharhinid sharks were the most fragile, while stingrays, guitarfish, and tawny nurse sharks generally survived well.⁶

Bigger Ecological Consequences of Removing Sharks

Beyond bycatch, the concern is what happens to the broader ecosystem when large shark populations decline. Sharks sit at or near the top of marine food webs, and removing them can set off chain reactions. One widely cited study in the northwest Atlantic found that as abundances of all 11 great shark species fell over 35 years, 12 of 14 prey species (rays, skates, and small sharks) increased. The cascade went further: cownose rays, freed from shark predation, ate so many bay scallops that a century-old scallop fishery collapsed.⁷

Another documented example involves white sharks and sevengill sharks in South Africa’s False Bay. When white sharks disappeared from a foraging site at Seal Island, sevengill sharks moved in and began filling the vacated ecological role, including attacking live seals. This was unprecedented behavior for sevengills, which normally inhabit kelp-associated environments rather than open-water seal colonies.⁸ The finding illustrates that removing one apex predator does not simply leave a gap; another species may shift its behavior to exploit the opening, with unpredictable consequences.

That said, the evidence for these trophic cascades is not uniform across all marine ecosystems. On coral reefs, for instance, the picture is murkier. The high diversity of species and functional redundancy among reef organisms makes it harder for the removal of one predator to cascade cleanly through the food web. Models suggesting that shark declines on reefs trigger cascading effects have been challenged on the basis that reef food webs are too complex for simple top-down control to dominate.⁹ So the ecological argument against culling is strong in some settings and less definitive in others, which is exactly the kind of nuance that gets lost in public debate.

SMART Drumlines as a Middle Ground

SMART stands for “shark management alert in real-time,” and the technology represents an attempt to split the difference between safety and conservation. A SMART drumline works the same way as a traditional drumline, except that when an animal is hooked, the buoy sends an electronic alert to a contractor’s phone or pager. The contractor then arrives quickly, tags the shark with a tracking device, and releases it alive.

The speed of response matters for animal welfare. Because animals spend less time on the hook, typically under 30 minutes, most are released in good condition.¹⁰ Research on white sharks caught on SMART drumlines found minimal physiological disturbance: of 18 blood markers analyzed, only lactate and one liver enzyme showed significant increases with time on the line, and those increases were modest.¹¹ In practical terms, the sharks seem to tolerate brief capture reasonably well.

SMART drumlines also generate data. Every tagged shark becomes a data point for tracking movements, identifying hotspots, and understanding when and why sharks come close to shore. Over time, that data can improve beach management decisions. The tradeoff is that SMART drumlines are more labor-intensive and expensive than traditional drumlines, since each alert requires a boat crew to respond. And they are not foolproof: a trial in the high-energy Capes region of Western Australia found that SMART drumlines were ineffective at catching white sharks there, with acoustic detections confirming that sharks were present but simply not taking the bait.¹⁰ What works in one area may not transfer easily to another.

Non-Lethal Alternatives and How Well They Work

Critics of culling programs often point to non-lethal alternatives, but these range widely in how proven they are. Some are already operational, others remain experimental, and a few are more wishful thinking than reliable technology.

Drone surveillance has become one of the most visible alternatives. Drones fly over beaches, and operators scan for sharks in the water below. The limitation is detection rate. In a drone patrol program in southeast Queensland, sharks were spotted on only about 3% of flights across all beaches surveyed, similar to a New South Wales trial where only about 2% of flights detected bull, white, or whaler sharks.¹² That does not mean drones are useless, but it does mean they miss most sharks, especially in murky or choppy water. They work best as one layer in a multi-tool system rather than as a standalone replacement for nets.

Acoustic telemetry buoys represent a complementary technology. These are underwater receivers that detect acoustically tagged sharks in real time and relay alerts to beach managers. Real-time buoys have been shown to provide reliable detection in dynamic nearshore environments and offer immediate data access, which is valuable for making rapid closure decisions when a tagged shark enters a swimming zone.¹³ The catch is that only previously tagged sharks trigger an alert, so the system is only as good as the tagging effort that feeds it.

Personal electric deterrents have received considerable attention. Testing on white sharks found that one device, the Freedom+ Surf, reduced the proportion of bait taken from 96% down to 40% and roughly doubled the average distance sharks kept from a surfboard. However, several other commercial deterrent products, including a magnetic bracelet and a repellent wax, showed limited or no measurable effect on shark behavior.¹⁴ Scaling up electric deterrents to protect an entire beach has proven even harder. A long-range electric deterrent designed to cover a wider area reduced bait-taking by roughly a quarter at 80 volts and by about half at 150 volts, but high variance in the results made the effect statistically unreliable, and the coverage area remained limited.¹⁵

One of the more unusual lines of research involves chemical repellents derived from dead shark tissue. A compound created from putrefied shark flesh proved completely repellent to Caribbean reef sharks and blacknose sharks during competitive feeding experiments in the Bahamas. Doses as small as 150 milliliters, delivered from a pressurized canister, triggered immediate aversive responses in groups of up to nine feeding sharks.¹⁶ Whether this works on the larger, more dangerous species in open-ocean conditions is an open question, but the principle that sharks strongly avoid the chemical signals of dead conspecifics is intriguing.

Public Attitudes and the Economics of Beach Safety

One reason shark culling persists despite ecological objections is economic. Beach tourism is a major industry in coastal regions of Australia and South Africa, and governments face genuine pressure to keep beaches feeling safe. An economic study of Durban beach in South Africa estimated that removing protective shark nets would decrease recreational visits by more than 20%, with the size of the drop depending on whether visitors typically enter the water, whether they had heard about past shark incidents, and their general risk tolerance.¹⁷ A 20% decline in beach visits translates into a real economic loss for local businesses, lifeguard services, and municipal revenue. Politicians weighing these numbers have a strong incentive to keep some form of visible protection in place, even if the ecological cost is high.

Public opinion, interestingly, may be more nuanced than policymakers assume. A pilot survey conducted in Cape Town’s Fish Hoek and Muizenberg neighborhoods before and after a shark bite found that levels of “pride” in local white shark populations remained steady even after the incident. Confidence in beach safety programs and attitudes toward other marine life also did not change significantly.¹⁸ That suggests a previously undocumented level of public sophistication: at least in some communities, a single shark bite does not automatically trigger calls for lethal intervention.

Media framing has also been examined as a driver of public fear. In an experiment where participants were exposed to different types of shark-related headlines (sensational attack coverage, statistical framing, non-attack stories, and neutral content), researchers found no significant differences between conditions on perceived risk, acceptance of sharks, blame toward sharks, or mitigation preferences.¹⁹ Headlines may matter less than commonly thought, at least in controlled settings. Real-world media cycles are harder to study, but the finding challenges the assumption that sensationalized “Jaws”-style coverage is the primary driver of public support for culling.

Why the Debate Is Unlikely to Resolve Soon

The controversy over shark culling is not a simple factual disagreement waiting to be settled by more data. It sits at the intersection of several genuinely competing values: the immediate safety of beachgoers, the long-term health of marine ecosystems, the economic interests of coastal communities, and evolving societal attitudes about how humans should relate to wildlife. People who emphasize different values will look at the same evidence and reach different conclusions, and both can be acting in good faith.

What has shifted in the last decade or so is the menu of options. Governments no longer face a binary choice between lethal nets and doing nothing. SMART drumlines, drone patrols, acoustic receiver networks, personal deterrents, and chemical repellents all represent partial solutions that can be combined. None of them is a silver bullet, but layered together, they begin to approximate a system that can manage risk without the same level of ecological damage as traditional nets. The sticking point is cost and political will: non-lethal systems require ongoing investment, trained personnel, and a public willing to accept that no approach will reduce the risk of shark encounters to zero. Whether communities and governments embrace that tradeoff or cling to the perceived certainty of lethal methods is what keeps the debate alive.

The Welfare Question for Sharks Themselves

A strand of the controversy that gets less attention than bycatch or ecosystem effects is the welfare of the individual sharks caught in control programs. Even when SMART drumlines are used and the intent is catch-and-release, being hooked and restrained is a physiologically stressful event for a shark. The research showing minimal blood chemistry changes in white sharks after brief capture is reassuring to a point, but it applies specifically to white sharks held for short periods.¹¹ Other species respond differently. Scalloped hammerheads and small carcharhinids are far more fragile and have higher mortality on drumlines even with rapid response times.⁶

For traditional nets, the welfare picture is grimmer. Animals that become entangled may struggle for hours or days before drowning or being removed. Dolphins and turtles, which must surface to breathe, face especially high mortality in gill nets. As societal attitudes toward animal sentience evolve, these welfare costs are increasingly difficult to defend, particularly for species with documented cognitive complexity. The question is not just whether culling programs affect populations, but whether the suffering imposed on individual animals is ethically acceptable given the existence of alternatives that, while imperfect, could substantially reduce that suffering.

1
African Journal of Marine Science. Gear selectivity of large-mesh nets and drumlines used to catch sharks in the Queensland Shark Control Program
2
Marine and Freshwater Research. Shark control: experimental fishing with baited drumlines
3
Marine and Freshwater Research. Reducing the environmental impact of shark-control programs: a case study from KwaZulu-Natal, South Africa
4
People and Nature. Effects and effectiveness of lethal shark hazard management: The Shark Meshing (Bather Protection) Program, NSW, Australia
5
Fisheries Research. The influence of bait position on the catch of target and non-target sharks in a SMART drumline bather protection program
6
Fisheries Research. An innovative fishing gear to enhance the release of non-target species in coastal shark-control programs: The SMART (shark management alert in real-time) drumline
7
PubMed. Cascading effects of the loss of apex predatory sharks from a coastal ocean
8
PubMed Central. Disappearance of white sharks leads to the novel emergence of an allopatric apex predator, the sevengill shark
9
PubMed Central. Emerging insights on effects of sharks and other top predators on coral reefs
10
PubMed Central. SMART Drumlines Ineffective in Catching White Sharks in the High Energy Capes Region of Western Australia: Acoustic Detections Confirm That Sharks Are Not Always Amenable to Capture
11
Conservation Physiology. The acute physiological status of white sharks (Carcharodon carcharias) exhibits minimal variation after capture on SMART drumlines
12
PubMed Central. Factors Affecting Shark Detection from Drone Patrols in Southeast Queensland, Eastern Australia
13
Journal of Marine Science and Engineering. Real-Time Acoustic Telemetry Buoys as Tools for Nearshore Monitoring and Management
14
PubMed Central. Effectiveness of five personal shark-bite deterrents for surfers
15
ICES Journal of Marine Science. Long-range electric deterrents not as effective as personal deterrents for reducing risk of shark bite
16
Ocean & Coastal Management. Chemical shark repellent: Myth or fact? The effect of a shark necromone on shark feeding behavior
17
ScienceDirect. Hazardous human–wildlife encounters, risk attitudes, and the value of shark nets for coastal recreation
18
ScienceDirect. Shark bites and public attitudes: Policy implications from the first before and after shark bite survey
19
ScienceDirect. The impact of news media portrayals of sharks on public perception of risk and support for shark conservation