News
Shark culls don’t work. Here’s what actually keeps people safe.
Monday, 27 Jul, 2026
There is no clear evidence that killing sharks reduces the risk of future shark bites.
Written by Sarah Dawson- NSW volunteer Shark Defence Coordinator and Dirk Holman- Threatened Species Researcher
When shark bite incidents happen, calls for a shark cull often surface. However, killing sharks is not synonymous with reducing the risk of future shark bites. In this blog, we answer frequently asked questions surrounding shark bite mitigation and address why culling sharks is not an effective solution to keeping people safe.
Q: Do shark culls reduce the risk of shark bites?
No. The evidence does not show that lethal shark control reliably reduces shark bite risk.
Scientific evidence shows that shark bite risk is influenced by multiple interacting factors, including ocean conditions, human water use, prey distribution and movement, climate, shark behaviour, and coastal development. It is not simply a case of "fewer sharks equals fewer bites”
Q: Why don’t shark culls work?
One reason is that sharks are highly mobile. Bull sharks in particular move between rivers, estuaries, and coastal waters, with their distribution varying according to season, water temperature, life stage, and habitat. Studies in eastern Australia have shown that bull shark abundance and residency are associated with warmer water temperatures, estuary mouths, mid-shelf habitats, and warmer-than-average months.
As a result, culling assumes a level of control that does not reflect how sharks use the environment. There is no fixed local population that can simply be removed to make an area safe.
Factors that play a role in shark behaviour and increased risks.
Shark bite risk is not determined by shark numbers alone. A global review shows that risk is influenced by multiple interacting factors, including human water use, coastal development, environmental conditions, prey availability and movement, mitigation measures, and shark behaviour.
As a result, removing sharks does not address the underlying factors that influence where they are found. Instead, the risk of shark encounters is shaped by a complex interaction of environmental and human factors that determine when and where sharks and people are most likely to come into contact.
Q: What does real-world evidence show?
Hawaii is one of the clearest examples. Between 1959 and 1976, shark control programs killed 4,668 sharks, but researchers found the programs did not appear to have a measurable effect on shark attack rates in Hawaiian waters.
In Australia, decades of shark control programs via the use of lethal drumlines and shark nets have killed thousands of sharks, yet there is no clear evidence that they provide a consistent or long-term reduction in shark bite risk. In New South Wales, researchers found no detectable difference in shark interaction rates between netted and non-netted beaches since the 2000s.
Q: Have bull shark numbers exploded?
There is no strong scientific evidence that bull shark numbers have “exploded” in Australia.
Instead, the science shows that bull shark presence varies with season, water temperature, and habitat. A seven-year acoustic tracking study in Sydney Harbour found that bull sharks were most abundant during summer and autumn, with numbers peaking in January and February. Water temperature was the strongest predictor of their seasonal movements and return to the harbour.
A telemetry study along eastern Australia found that bull shark abundance increased at southern latitudes during summer and autumn, particularly around estuary mouths and mid-shelf habitats. These seasonal distribution patterns can increase the likelihood of shark–human interactions but do not provide evidence of an increase in overall bull shark population size.
Q: What conditions increase the risk of a bull shark encounter?
Bull shark presence is strongly influenced by environmental conditions.
In Sydney Harbour, bull shark abundance peaked during January and February, with water temperature identified as the strongest predictor of seasonal movements and return to the harbour.
These findings suggest that shark safety should focus on identifying and communicating periods and locations of elevated risk, rather than responding with shark culls after incidents occur. Timely warnings, informed by environmental conditions and monitoring, can help people make safer decisions about when and where to enter the water.
Q: Why are bull sharks important for marine ecosystems?
Bull sharks play an important role in maintaining healthy marine ecosystems.
As apex predators, they move between rivers, estuaries, and coastal waters, linking different habitats and influencing food webs across these environments. Research suggests that their broad use of habitats and prey helps connect ecological processes across marine ecosystems, contributing to ecosystem structure and function.
Q: Fishermen claim to be witnessing increases in shark numbers. Does this mean shark numbers are increasing overall?
Reports of an explosion in shark populations are often cited to justify a shark cull, but the available scientific evidence does not support the claim of a shark population explosion.
An increase in shark sightings does not necessarily indicate an increase in the overall shark population. It may be due to changes in shark distribution, environmental conditions, monitoring efforts, or human activity, or attraction to fishing activity and food sources, rather than a genuine increase in overall shark numbers. Read more about this in our blog: Sharks in plague numbers? What the science really shows.
Q: Do shark culls harm the ocean?
Yes. The impacts extend well beyond sharks themselves.
Many shark species are apex predators that help maintain healthy marine ecosystems. Removing them can trigger cascading effects throughout the food web. For example, a landmark in the north-west Atlantic found that declines in large sharks were followed by increases in ray populations, which in turn depleted shellfish populations.
More recent research from South Africa found that the disappearance of white sharks was associated with increases in some prey and mesopredator species and declines in the species they consume, demonstrating how the loss of an apex predator can reshape an entire ecosystem.
Because sharks play a vital ecological role, many scientists argue that efforts to improve swimmer safety should focus on reducing the likelihood of shark–human interactions rather than removing predators from the ocean. This includes providing timely warnings, reliable information, and practical tools that help people make safer decisions about when and where to enter the water.
Q: What actually keeps people safe in the ocean?
No measure can eliminate the risk of shark bites entirely. The most effective approach is a layered strategy that reduces the likelihood of shark–human interactions while ensuring a rapid response if an incident does occur.
This includes:
Education about when and where risk is higher
Drones and aerial surveillance to detect sharks
Real-time alerts and temporary beach closures
Personal deterrent devices for surfers, divers, and ocean swimmers
Strong beach safety practices and clear public communication
Shark bite trauma kits and emergency response planning
Together, these measures help prevent shark–human interactions wherever possible and improve preparedness in the rare event of a shark bite. Unlike culling, they can be adapted to changing environmental conditions and provide a more targeted, evidence-based approach to improving ocean safety.
Queensland's KPMG Shark Control Program Evaluation Report concluded that the state's shark control program should modernise and progressively move away from environmentally harmful measures such as traditional shark nets and drumlines. The review supports greater use of targeted, non-lethal approaches, including emerging technologies and trial programs.
Q: How can I take action?
You can help advocate for evidence-based shark safety solutions that protect both people and marine life.
Support Sea Shepherd's campaigns by signing petitions calling on governments to remove shark nets and invest in modern, non-lethal technologies that improve ocean safety while protecting marine wildlife. Find out more here.
Research links
Shark Bite Risk and Drivers of Shark Interactions
Duval, D., Mangeas, M., Huveneers, C., Barnett, A. & Vigliola, L. (2025). Global systematic review of the factors influencing shark bites. Global Ecology and Conservation, 62, e03684.
https://www.sciencedirect.com/science/article/pii/S0025326X24003055
Bull Shark Ecology, Movement and Feeding Behaviour
Lee, K.A., Smoothey, A.F., Harcourt, R.G., Roughan, M., Butcher, P.A. & Peddemors, V.M. (2019). Environmental drivers of abundance and residency of a large migratory shark, Carcharhinus leucas, inshore of a dynamic western boundary current. Marine Ecology Progress Series, 622, 121–137.
https://doi.org/10.3354/meps13052
Daly, R., Froneman, P.W. & Smale, M.J. (2013). Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis. PLOS ONE, 8(10), e78229.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078229
Shark Abundance, Monitoring and Population Trends
Monteforte, K.I.P., Butcher, P.A., Morris, S.G. & Kelaher, B.P. (2022). The Relative Abundance and Occurrence of Sharks off Ocean Beaches of New South Wales, Australia. Biology, 11(10), 1456.
https://pubmed.ncbi.nlm.nih.gov/36290360/
Smith, A., Songcuan, A., Mitchell, J., Haste, M., Schmidt, Z., Sands, G. & Lincoln Smith, M. (2022). Quantifying Catch Rates, Shark Abundance and Depredation Rate at a Spearfishing Competition on the Great Barrier Reef, Australia. Biology, 11(10), 1524.
https://www.mdpi.com/2079-7737/11/10/1524
Shark Behaviour, Movements and Distribution
Meyer, C.G., Holland, K.N. & Papastamatiou, Y.P. (2009). Movements of Tiger Sharks (Galeocerdo cuvier) in Coastal Hawaiian Waters.
Ecological Impacts of Shark Removal
Myers, R.A., Baum, J.K., Shepherd, T.D., Powers, S.P. & Peterson, C.H. (2007). Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean. Science, 315(5820), 1846–1850.
https://trophiccascades.forestry.oregonstate.edu/sites/default/files/Myers%20et%20al%202007.pdf
Hammerschlag, N., Herskowitz, Y., Fallows, C. & Couto, T.B.A. (2025). Evidence of Cascading Ecosystem Effects Following the Loss of White Sharks from False Bay, South Africa. Frontiers in Marine Science, 12, 1530362.
https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2025.1530362/full
Policy and Program Reviews
KPMG. (2024). Shark Control Program Evaluation Report. Report for Queensland Department of Agriculture and Fisheries.
Queensland Government. (2025). Queensland Shark Management Plan 2025–2029.
https://www.dpi.qld.gov.au/business-priorities/fisheries/shark-management-plan