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Shark net
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A shark net is a submerged section of gillnets placed at beaches designed to intercept large marine animals including sharks, with the aim to reduce the likelihood of shark attacks on swimmers. The gillnets form a wall of netting that hangs in the water and captures the marine animals by entanglement.
Shark nets do not create an exclusion zone between sharks and humans, and are not to be confused with shark barriers.
Shark nets do not completely prevent shark attacks in the enclosed area, but work on the principle of "fewer sharks, fewer attacks". Specifically, they aim to reduce occurrence of attacks by entangling and via shark mortality. Shark nets such as those in New South Wales are designed to entangle and capture sharks that pass near them.[1] Reducing the local shark populations reduces the chance of an attack.
Historical shark attack figures suggest that the use of shark nets and drumlines does markedly reduce the incidence of shark attack when implemented on a regular and consistent basis.[2][3][4] However a 2019 study argued this conclusion overlooks key factors.[5] The large mesh size of the nets is designed specifically to capture sharks and prevent their escape until eventually, they drown. Due to boating activity, the nets also float 4 metres or more below the surface and do not connect with the shoreline (excluding Hong Kong's shark barrier nets) thus allowing sharks the opportunity to swim over and around nets. Shark nets can cost A$1 million or A$20,000 per beach per year.[6]
Shark nets have been criticized by environmentalists, conservationists and animal rights activists — they say shark nets are unethical and harm the marine ecosystem.[7][8][1][9][10][11] They also argue there is no science showing that nets make the ocean safer for people.[1] Only around 10% of catch in shark nets is the intended target shark species.[12][13]
Shark nets vary in size. The nets in Queensland, Australia, are typically 186m long, set at a depth of 6m, have a mesh size of 500mm and are designed to catch sharks longer than 2m in length.[14] The nets in New South Wales, Australia, are typically 150m long, set on the sea floor, extending approximately 6m up the water column, are designed to catch sharks longer than 2m in length.[15]
History
[edit]Shark net meshing was developed by the New South Wales Fisheries in 1937, after a decade and a half of repeated shark attacks off Sydney beaches. In March 1935, for example, two people — one at North Narrabeen and one at Maroubra — perished after great white shark attacks in a single week. The meshing was never designed to enclose a piece of water, as barrier nets couldn't survive a surf zone. Instead, it was designed to catch large sharks as they swam within range of the surf. At first, the catch was huge; over 600 sharks in the first year of operation, off just a few Sydney beaches. But over time, even without adjusting for the spread of the program across almost all Sydney beaches and into Wollongong and Newcastle, the catch declined. Today's New South Wales meshing annual average catch is 143 sharks, many of which are released alive.[16]
Nets were first deployed off certain beaches in KwaZulu-Natal (formerly Natal), South Africa, in 1952.[3]
Shark nets were also used off Dunedin, New Zealand for roughly 40 years, and were removed in 2011. The nets were found to be detrimental to the environment; 700 non-target species were killed.[17] No shark attacks have occurred since their removal.[18]
As of 2018, shark nets are used in New South Wales, Queensland and KwaZulu-Natal.[11][19][20] In August 2018, it was announced that the nets in northern New South Wales would be removed, but that the nets in Sydney, Newcastle and Wollongong would stay.[8][21] The New South Wales Green party said they wanted all shark nets removed.[21]
Effectiveness
[edit]Ongoing shark control programs have been very successful in reducing the incidence of shark attack at the protected beaches.[3][22][4] In the years from 1900 to 1937, 13 people died off New South Wales surf beaches after shark attacks; over the next 72 years, the death rate fell to eight, only one of which was at a meshed beach. This in a period when the New South Wales human population rose from 1.4 million to seven million — and when more people began going to the beach.[16]
In Queensland, there has been only one fatal attack on a controlled beach since 1962, compared to 27 fatal attacks between 1919 and 1961. Statistics from the New South Wales Department of Primary Industries indicate that before nets were introduced in New South Wales in 1936 there was an average of one fatal shark attack every year. There has been only one fatal attack on a protected beach since then and that was in 1951. Similarly, between 1943 and 1951 the South African city of Durban experienced seven fatal attacks but there have been none since nets were introduced in 1952. A more recent comparison shows that in South Africa there were three shark attacks, none fatal, at protected beaches in KwaZulu-Natal between 1990 and 2011, while there were 20 fatal attacks in the same period at unprotected beaches in the Eastern and Western Cape Provinces.[2]
However, the net program in New South Wales has been called "outdated and ineffective" by environmental groups;[8] they argue that shark nets do not protect swimmers.[1] 65% of shark attacks in New South Wales occurred at netted beaches.[9]
Environmental impact
[edit]Shark nets result in incidence of bycatch, including threatened and endangered species like sea turtles, dugongs, dolphins and whales.[23] In Queensland in the 2011/12 summer season there were 700 sharks caught, 290 above 4 metres in shark nets and drum lines.[24]
In New South Wales, the meshing averages one humpback whale every two years; the whale is almost always released alive. In Queensland in 2015, the bycatch included one bottlenose and seven common dolphin (one released alive), 11 catfish, eight cow-nose rays, nine eagle rays, 13 loggerhead turtles, five manta rays (all but one survived), eight shovelnose rays, three toadfish, four tuna, and a white spotted eagle, which was safely released.[16]
New South Wales and Queensland also utilize acoustic pingers attached to the nets to reduce bycatch of dolphins, whales and other marine mammals.[25] Use of the pingers has been shown to significantly reduce marine mammal bycatch.[26]
The current net program in New South Wales has been described as being "extremely destructive" to marine life.[27] Between September 2017 and April 2018, more than 403 animals perished in the nets in New South Wales, including 10 critically endangered grey nurse sharks, 7 dolphins, 7 green sea turtles and 14 great white sharks.[8] Between 1950 and 2008, 352 tiger sharks and 577 great white sharks died in the nets in New South Wales — also during this period, a total of 15,135 marine animals perished in the nets.[11] More than 5,000 marine turtles have been caught on the nets.[9] The New South Wales government prohibits people from rescuing entangled animals — this prohibition has been called "heartless and cruel".[10]
In a 30-year period, more than 33,000 sharks have perished in KwaZulu-Natal's shark net program.[20] During the same 30-year period, 2,211 turtles, 8,448 rays, and 2,310 dolphins died in KwaZulu-Natal's shark net program.[20]
Controversy
[edit]The continued use of shark nets has generated debate between those prioritising swimmer safety and those opposing the ecological toll of the programs.
Shark nets do not create a complete barrier, as they extend only a few metres below the surface and can be bypassed by sharks swimming over or around them.[28] Following a fatal shark attack at a netted Sydney beach in 2025, researcher Chris Pepin-Neff described the nets as “like throwing a napkin into the pool.”[28]
A 2025 review by the New South Wales Threatened Species Scientific Committee found no measurable evidence that the presence of nets significantly reduced shark-bite incidents compared with non-netted beaches.[29]
Political scientist Christopher Neff notes, "Internationally, shark nets have been labeled a 'key threatening process' for killing endangered species." He adds: " ... killing endangered species to boost public confidence or to show government action is not workable. It is a disservice to the public."[7] Jessica Morris of Humane Society International calls shark nets a "knee-jerk reaction" and says, "sharks are top order predators that play an important role in the functioning of marine ecosystems. We need them for healthy oceans."[9] Sea World Research & Rescue Foundation also oppose the use of shark nets to cull shark populations "In an ideal world we would like for there to be no culling of sharks in Australia and around the world however, this is not a reality. We understand the pressure on governments to protect swimmers through the use of shark control programs. We continue our stance against shark nets and maintain our rescue operations to save dolphins, whales, turtles that become entrapped within them, along with working with the authoritative agencies to research improved methods which will lessen the impact on our marine life".[30]
Animal welfare groups note the suffering and cruelty that nets inflict upon animals, such as lacerations, stress, pain, and disease.[9] They suggest alternatives such as surf lifesaving patrols, public education on shark behaviour, radio signals, sonar technology and electric nets.
While most environmental groups call for the nets’ removal, some commentators argue that their ecological harm is overstated. Australian surf journalist Nick Carroll wrote in The Telegraph that the impact of shark nets “is less than commonly thought” and that their safety benefits for swimmers and surfers outweigh the environmental cost.[31]
His arguments have been contested by marine scientists and conservation organisations, who cite government bycatch data and maintain that non-lethal deterrents can provide equivalent safety without the same ecological toll.[32]
Comparisons with commercial fishing are also cited in debate. On average 15 Great white sharks are caught by the NSW and Queensland shark control programme each year, compared to 186 caught in Australia from other activities.[33] Australia's commercial shark fishing industry is catching over 1200 tonne of shark each year,[16] of which 130 are Great white sharks.[33] The NSW prawn trawling industry alone results in 64 tonne of shark as bycatch each year,[16] with two thirds dying.[34] Tuna and swordfish longline fishing off the coast of South Africa reported 39,000 to 43,000 sharks died each year between 1995 and 2005.[34] Sharksavers estimates that in total 50 million sharks are caught unintentionally each year as bycatch by the commercial fishing industry.[35]
Plans by the New South Wales government to trial the removal of shark nets from selected beaches were paused in 2025 after a fatal attack, citing safety concerns while investigations continued.[36] Several local councils and conservation groups continue to advocate replacing nets with modern technologies such as SMART drumline systems, drones, and acoustic monitoring networks.[37]
Cost
[edit]Total cost for the Shark netting program in NSW for the 2009/10 year was approximately AUD $1m, which included the cost of the nets, contractors, observers and shark technician, shark meshing equipment (dolphin pingers and whale alarms etc.), and compliance audit activities.[6] For the 51 beaches protected,[6] this represents a financial cost of approximately AUD$20,000 per beach per year.
Australia
[edit]In New South Wales, Australia, 51 beaches are netted.[38] The nets are maintained by the New South Wales Department of Primary Industries. The nets are generally 150 metres long, 6 m wide and "bottom-set" on the seabed in depths of 10 m. The nets can be 500 metres from the beach. The mesh is sized 50–60 centimetres. Nets are lifted every 24 to 48 hours for servicing so as to prevent rotting, to clean out debris and to remove dead sharks and other marine life. It is said that 35–50% of the sharks are entangled from the beach side. Acoustic "pingers" have been fitted to the nets to warn off dolphins and whales and the nets are not in place in winter, the whale migration season. The department states that the nets have "never been regarded as a means of absolutely preventing any attacks", but help to deter sharks from establishing territories.[39] From 1950 to 2008, hundreds of great white sharks and tiger sharks perished in the nets in New South Wales.[11]
In Queensland, Australia, drum lines are used in combination with shark nets. Queensland's Shark Control Program has been in place since the early 1960s. In Queensland's 2011/12 summer season there were 714 sharks caught, 281 above 2 metres in shark nets and drum lines.[24] Since 1997, 500-900 sharks perished annually in the program, including several shark species of conservation concern. They include the following:
| Common name | Scientific name | IUCN Redlist status | EPBC conservation listing (AUS) |
|---|---|---|---|
| Great hammerhead | Sphyrna mokarran | Endangered[40] | |
| Great white shark | Carcharodon carcharias | Vulnerable[41] | Vulnerable[42] |
| Grey nurse shark | Carcharias taurus | Vulnerable[43] | Critically Endangered (East Coast) Population[42] |
| Scalloped hammerhead | Sphyrna lewini | Endangered[44] |
A fatal attack in Queensland occurred in January 2006 at Amity Point on North Stradbroke Island. The water at this location drops off to 30 metres depth, and bull sharks are known to frequent the area.[45] Drum lines were installed at beaches around the island at the time.[46] Another shark attack occurred at Greenmount Beach on the Gold Coast in 2020. Drumlines and shark nets were installed at the beach at this time.[47]
Following a fatal attack in 2025 on one of Sydney's northern beaches, the state government paused plans for removal of shark nets from three beaches.[48]
South Africa
[edit]In South Africa, shark nets are installed at numerous beaches in KwaZulu-Natal by the KwaZulu-Natal Sharks Board.[49] Shark nets have been installed in KwaZulu-Natal since the 1950s[20] and have greatly reduced the number of shark attacks along the beaches where they are installed.[4] However more than 33,000 sharks have perished in KwaZulu-Natal's nets in a 30-year period.[20] KwaZulu-Natal's shark net program has been called "archaic" and "disastrous to the ecosystem".[20]
See also
[edit]References
[edit]- ^ a b c d Forrest, Alice (2014-09-10). "Shark Nets in Australia – What Are They and How Do They Work?". sealifetrust.org. Archived from the original on October 16, 2018. Retrieved October 17, 2018.
- ^ a b "Can governments protect people from killer sharks?". ABC News. 22 December 2013. Retrieved 22 April 2017.
- ^ a b c Curtis; et al. (2012). "Responding to the risk of white shark attack: updated statistics, prevention, control, methods and recommendation. Chapter 29 In: M. L. Domeier (ed). Global Perspectives on the Biology and Life History of the White Shark". CRC Press. Boca Raton, FL. Retrieved 18 January 2020.
- ^ a b c "Shark attacks on the South African coast between 1960 and 1990". South African Journal of Science. 87 (10): 513–518. October 1991. Retrieved 22 November 2018.
- ^ Gibbs, Leah; Fetterplace, Lachlan; Rees, Matthew; Hanich, Quentin (2 December 2019). "Effects and effectiveness of lethal shark hazard management: The Shark Meshing (Bather Protection) Program, NSW, Australia". People and Nature. 2: 189–203. doi:10.1002/pan3.10063. S2CID 213735780.
- ^ a b c Green, M., Ganassin, C. and Reid, D. D. "Report into the NSW Shark Meshing (Bather Protection) Program" (PDF). State of New South Wales through NSW Department of Primary Industries. Retrieved 21 December 2016.
{{cite web}}: CS1 maint: multiple names: authors list (link) - ^ a b Pepin-Neff, Christopher (12 October 2011). "The Untold Story of Shark Nets in Australia". theconversation.com. Retrieved October 17, 2018.
- ^ a b c d Mackenzie, Bruce (August 4, 2018). "Sydney Shark Nets Set to Stay Despite Drumline Success". swellnet.com. Retrieved October 17, 2018.
- ^ a b c d e Morris, Jessica (December 8, 2016). "Shark Nets – Death Traps For Marine Animals". hsi.org.au. Retrieved October 17, 2018.
- ^ a b Eddie, Rachel (January 9, 2018). "Threat to Cut Shark Nets if Government Fails to Act". thenewdaily.com. Retrieved October 17, 2018.
- ^ a b c d "Shark Culling". marineconservation.org.au. Retrieved October 17, 2018.
- ^ Fisheries, NOAA. "Gillnets: Fishing Gear and Risks to Protected Species :: NOAA Fisheries". Retrieved 22 April 2017.
- ^ "Council calls for removal of shark nets on the Northern Beaches". 28 April 2021. Retrieved 19 March 2022.
- ^ "Shark control equipment and locations". Retrieved 22 April 2017.
- ^ "Shark Nets - SharkSmart - NSW Government". 2 August 2021. Retrieved 19 March 2022.
- ^ a b c d e Media, Australian Community Media - Fairfax (8 November 2016). "Beyond the panic: the facts about shark nets". Retrieved 22 April 2017.
- ^ Benson, Nigel (2011-11-17). "Dunedin shark-nets film 'positive environmental story'". Otago Daily Times. Retrieved 2024-09-13.
- ^ "Recorded shark attacks in New Zealand to 2014 - Te Ara". Retrieved 19 March 2022.
- ^ "Shark Defence Campaign". Sea Shepherd Australia. Retrieved 2024-09-13.
- ^ a b c d e f "Shark Angels - Turning Fear Into Fascination". SHARK ANGELS. Retrieved 2024-09-13.
- ^ a b "Shark nets to be removed from all NSW north coast beaches". The Guardian. 2018-08-17. ISSN 0261-3077. Retrieved 2024-09-13.
- ^ Dudley, S.F.J. (1997). "A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa)". Ocean Coast Manag. 34 (34): 1–27. Bibcode:1997OCM....34....1D. doi:10.1016/S0964-5691(96)00061-0.
- ^ "Baby whale dies in shark net". News24. July 19, 2004. Archived from the original on March 22, 2005. Retrieved March 22, 2005.
- ^ a b "Data Tables: Shark control program: Sharks caught by area, Queensland, 2002–03 to 2012–13 (OESR, Queensland Treasury)". Oesr.qld.gov.au. 2013-07-26. Retrieved 2013-09-11.
- ^ "Subscribe - theaustralian". Retrieved 22 April 2017.
- ^ Barlow, Jay; Cameron, Grant A. (2003). "Field experiments show that acoustic pingers reduce marine mammal bycatch in the California drift gill net fishery". Marine Mammal Science. 19 (2): 265–283. doi:10.1111/j.1748-7692.2003.tb01108.x. S2CID 26969713.
- ^ Scott, Elfy (July 5, 2018). "Here's What You Need To Know About Australia's SMART Drum Lines Being Used To Prevent Shark Attacks". BuzzFeed. Retrieved October 17, 2018.
- ^ a b "Fatal attack revives debate over controversial shark nets in Australia". www.bbc.com. 2025-10-03. Retrieved 2025-10-12.
- ^ Miller, Melanie (2025-03-31). "government scientists condemn shark nets". Humane World for Animals. Retrieved 2025-10-12.
- ^ "Sea World Research & Rescue Foundation - What is the Foundation's opinion of the Shark Control Program?". Retrieved March 19, 2022.
- ^ Arylko (October 29, 2016). "11 shark net myths debunked as pro surfers freak out over attacks". The Daily Telegraph.
- ^ Claudiaj (November 1, 2016). "Surfer creates more shark myths, says marine ecologist". The Daily Telegraph.
- ^ a b H. Malcolm, B. D. Bruce and J. D. Stevens (September 2001). "A Review of the Biology and Status of White Sharks in Australian Waters". CSIRO Marine Research, Hobart: 93. Retrieved 8 December 2018.
- ^ a b Stephanie M. Bettis (July 2017). "Shark Bycatch in Commercial Fisheries: A Global Perspective". Nova Southeastern University. Retrieved 8 December 2018.
- ^ "Shark fin trade myths and truths" (PDF). Sharksavers. Retrieved 8 December 2018.
- ^ "Why shark nets are not effective at handling certain species". ABC News. 2025-09-08. Retrieved 2025-10-12.
- ^ "Shark nets to be removed early in NSW with future undecided". ABC News. 2025-03-27. Retrieved 2025-10-12.
- ^ "Summer is coming and so are the sharks". Smh.com.au. 2012-10-19. Retrieved 2013-09-11.
- ^ "NSW Shark Meshing publications | NSW Department of Primary Industries". Dpi.nsw.gov.au. Retrieved 2013-09-11.
- ^ "Sphyrna mokarran". The IUCN Red List of Threatened Species. International Union for the Conservation of Nature. Retrieved 2014-09-14.
- ^ "Carcharodon carcharias". The IUCN Red List of Threatened Species. International Union for the Conservation of Nature. Retrieved 2014-09-14.
- ^ a b "EPBC Act List of Threatened Fauna". Department of the Environment. Australian Government. 2014. Retrieved 2014-09-14.
- ^ "Carcharias taurus". The IUCN Red List of Threatened Species. International Union for the Conservation of Nature. Retrieved 2014-09-14.
- ^ "Sphyrna lewini". The IUCN Red List of Threatened Species. International Union for the Conservation of Nature. Retrieved 2014-09-14.
- ^ Wikinews:Woman killed in shark attack at Amity Point, Australia
- ^ Sarah Vogler. "Monster shark spreads fear off Queensland coast". Couriermail.com.au. Retrieved 2013-09-16.
- ^ "Gold Coast shark attack victim named as Nick Slater, Greenmount and Burleigh beaches closed". ABC News. abc.com.au. 8 September 2020. Retrieved 2022-10-29.
- ^ Messenger, Andrew (2025-09-07). "NSW is pausing its shark net reduction trial after fatal Long Reef beach attack. What's the plan this summer?". The Guardian. ISSN 0261-3077. Retrieved 2025-09-21.
- ^ [1] Archived March 31, 2009, at the Wayback Machine
External links
[edit]Shark net
View on GrokipediaDesign and Functionality
Materials and Construction
Shark nets are typically engineered as gillnet-style barriers using UV-resistant polyethylene webbing to endure marine conditions including saltwater corrosion, abrasion, and solar degradation. The mesh is constructed in a multifilament or braided configuration with stretched openings of approximately 50 cm, calibrated to entangle sharks exceeding 2 meters in length by gilling or snagging their gills, fins, or bodies.[13][14] Dimensions are standardized within programs but vary regionally for site-specific deployment. In Queensland's Shark Control Program, nets measure 186 m in length and 6 m in drop depth, with a mesh size of 500 mm. In KwaZulu-Natal's bather protection system, nets are 213.5 m long and 6.3 m deep, utilizing black flat braid polyethylene with a 51 cm stretched mesh.[14][15] Construction includes reinforced selvedges and integrated components for structural integrity, such as weighted footropes and buoyed headlines, to facilitate controlled positioning amid currents and wave action while minimizing drift. Regional adaptations may incorporate larger mesh trials, like 70 cm variants tested in KwaZulu-Natal since 1991, to reduce incidental capture of smaller marine life without compromising entanglement efficacy for target sharks.[16][17]Deployment and Maintenance
Shark nets in Australian programs, such as those operated by New South Wales, are deployed seasonally from early September to late March or April to correspond with heightened beach attendance and shark presence during warmer months.[18] Nets are positioned parallel to the shoreline, anchored to the seabed with weights at each end, typically 400 to 500 meters offshore in water depths of 10 to 12 meters to intercept sharks approaching swimming areas without fully enclosing beaches.[19][9] Installation requires specialized vessels to lay the nets, which span approximately 150 meters in length and 6 meters in depth, ensuring they hang vertically while allowing passage over or under for non-target species.[19] Deployment logistics account for local bathymetry and currents, with anchors adjusted to maintain position amid tidal fluctuations that can exceed 2 meters in some regions.[20] Ongoing maintenance entails daily or near-daily patrols by contractor-operated boats for drumlines in complementary programs, but net inspections occur every 72 hours under standard conditions, escalating to every 48 hours in high-risk periods like February and March to release bycatch promptly and assess structural integrity.[21][22] Crews remove entangled debris, such as seaweed or fishing line, which can compromise net efficacy, and repair tears from marine fouling or abrasion, with full retrieval and storage during off-seasons to prevent degradation. Fuel consumption for patrols, labor for manual checks, and periodic replacement of frayed mesh sections represent key operational inputs, as nets endure constant submersion and biofouling.[21] Adaptations for environmental variability include reinforced anchoring systems to withstand storm surges, which have historically delayed reinstallation by days or weeks, as seen in September 2025 at Sydney's Shark Beach following severe weather.[23] In areas with strong tidal ranges, nets may incorporate additional buoys or tension lines to prevent sagging or displacement, ensuring consistent deployment despite wave action up to 3 meters.[20] These measures address site-specific challenges, such as coral proximity in Queensland, where nets avoid sensitive reefs by precise seabed mapping prior to setting.[1]Mechanism of Operation
Shark nets function as gillnets, vertical panels of mesh suspended in the water column to capture sharks primarily through entanglement rather than physical obstruction. Typically 150 meters long and 6 meters deep with mesh openings of 50-60 centimeters, the nets are anchored to the seabed and buoyed at the surface, deployed parallel to shorelines in 10-12 meter depths about 500 meters offshore. This configuration targets large predatory species over 2 meters in length, including tiger sharks (Galeocerdo cuvier), great white sharks (Carcharodon carcharias), and bull sharks (Carcharhinus leucas), whose body girth exceeds the mesh size upon partial entry.[24][25] Upon contact, a shark's head, gills, fins, or dermal denticles snag in the mesh as it attempts passage or investigation, with forward momentum and netting barbs hindering withdrawal. Struggling exacerbates entanglement, depleting energy reserves; large sharks, reliant on ram ventilation—swimming to pump water over gill slits for oxygen—succumb to asphyxiation when immobilized. The gillnet principle exploits the mismatch between mesh aperture and animal dimensions, leading to progressive constriction without requiring active pursuit by operators.[26][25] These installations form partial barriers, vulnerable to bypass via submersion beneath the shallow depth or navigation around unsecured ends, particularly in currents or deeper zones. Operation hinges on passive interception, leveraging predatory sharks' investigatory behavior toward novel coastal structures rather than sensory repulsion, as the inert netting provides no chemical, visual, or electromagnetic deterrence.[24][27]Historical Development
Origins in South Africa
Shark nets were introduced along the beaches of Durban in KwaZulu-Natal (then Natal Province), South Africa, in 1952 as a direct response to a cluster of fatal shark attacks that heightened public concern for bather safety in this popular tourist area. Between 1943 and 1951, Durban recorded 21 shark attacks, including seven fatalities, amid increasing beach usage that amplified risks in waters frequented by large sharks such as Carcharodon carcharias and Carcharhinus leucas.[28][29] These incidents, verified through local records, underscored the empirical need for intervention in high-density swimming zones, where historical attack rates averaged several per year during peak periods, contrasting with rarer events elsewhere.[30] The nets, adapted from gillnet fishing techniques to create protective barriers approximately 400 meters offshore and parallel to the beach, were initially deployed off Durban's South Beach by the Durban Beach Committee, marking the first systematic use of such gear for human protection in South Africa.[31] This approach prioritized verifiable attack data over broader ecological speculation, targeting reduction of shark presence in nearshore areas through entanglement and selective culling. Early implementation focused on empirical outcomes, with nets set at depths of 5-10 meters to intercept sharks drawn to the warm, bait-rich waters off the subtropical coast.[32] In 1964, the Natal Provincial Administration established the Natal Anti-Shark Measures Board (later renamed the KwaZulu-Natal Sharks Board) as a statutory body to oversee net deployment, maintenance, and monitoring across protected beaches.[28][33] This formalized management responded to the program's initial success, with no fatal attacks recorded at netted Durban beaches since 1952, representing a stark decline from the pre-net average of 1-2 fatalities per decade in the region.[29] The Board's establishment ensured sustained operations based on ongoing attack logs and bather volume data, emphasizing causal links between net presence and reduced incidents in empirically high-risk locales.[34]Expansion to Australia
The shark meshing program in New South Wales was initiated in 1937 by the state fisheries department in direct response to a series of fatal shark attacks on Sydney beaches during the preceding decade and a half, including incidents that heightened public demand for protective measures.[7] Initial deployments consisted of 305-meter-long gill nets installed parallel to the shore at approximately 18 popular Sydney beaches starting in October 1937, marking Australia's adaptation of fixed-net technology to its temperate coastal environments and targeting large predatory species such as great white sharks (Carcharodon carcharias), which were more prevalent in local waters compared to tropical Indo-Pacific varieties.[35] The program was government-funded through public beach safety allocations, reflecting policy prioritization of bather protection amid growing urban coastal recreation.[36] Expansion within New South Wales accelerated in the 1960s, driven by empirical assessments of shark risks and surging beach visitation rates post-World War II, with a steep rise in the number of protected beaches and total netting length to accommodate heightened human-shark encounter potential.[37] By the 1970s, the program had scaled to encompass 51 key beaches along the coastline, stabilizing thereafter with minimal additions as coverage aligned with high-risk zones identified through incident data.[38] Queensland's shark control program, incorporating mesh nets alongside baited drum lines, commenced in 1962 following multiple fatal attacks that underscored localized threats in subtropical waters, with initial focus on southeastern beaches near Brisbane before broader rollout.[39] Like its New South Wales counterpart, it was financed via state budgets dedicated to public safety, customized for Queensland's longer continental shelf and migratory shark patterns, emphasizing capture of tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas) common to the region's river mouths and bays.[40] This development represented a parallel policy response to Australia-specific threat profiles, independent of contemporaneous South African efforts which postdated New South Wales implementations.[37]Global Adoption and Early Trials
In the mid-2010s, Réunion Island conducted limited trials of shark nets at select beaches, including Boucan Canot and Roches Noires, in response to a spike of over 20 shark attacks since 2011, resulting in multiple fatalities primarily from tiger and bull sharks.[41] [42] These installations, deployed as submerged gillnets to entangle approaching predators, represented one of the few international adaptations of the technology amid heightened public safety concerns, but expansion was curtailed by persistent bycatch of protected marine species and incomplete attack prevention.[43] Similarly, regions like Recife, Brazil, experienced sharp increases in shark incidents starting in 1992—linked to coastal development altering prey distribution and drawing bull and tiger sharks closer to shore—but opted against sustained shark net programs, favoring drum lines for targeted capture and relocation instead, which reportedly reduced attack rates by up to 97% before partial discontinuation due to logistical and ecological drawbacks.[44] Global uptake of shark nets has remained minimal due to prohibitive deployment and maintenance expenses, often exceeding hundreds of thousands of dollars annually per site; regulatory barriers stemming from international biodiversity protections, such as those under CITES for threatened shark species; and a inclination toward alternatives like localized culling, as seen in Hawaii's 1969–1987 program that targeted sharks via baited hooks at a cost of over $300,000 with limited verifiable reductions in encounters.[3] [45] In California, authorities have rejected nets and similar lethal interventions, prioritizing surveillance and behavioral advisories to avoid ecosystem disruption from non-selective gear.[46] Early 20th-century efforts beyond foundational implementations, such as reactive netting or capture operations following the 1916 Jersey Shore attacks that killed five people, proved ineffective for enclosing dynamic open-water zones and were largely abandoned in favor of vigilance or prohibition of bathing during high-risk periods.[47] These pilots underscored inherent limitations in scalability and reliability, contributing to the technology's confinement to a handful of high-incident locales rather than widespread endorsement.[48]Effectiveness for Human Safety
Empirical Data on Attack Reductions
In KwaZulu-Natal, South Africa, shark nets were deployed starting in 1952 following a series of fatal attacks, including seven documented fatalities off Durban beaches in the preceding years. Prior to implementation, the region experienced elevated shark-human interactions, with the majority of South Africa's recorded attacks in the early 20th century occurring along the KZN coast, contributing to disruptions in beach tourism. Since 1952, protected beaches have recorded 27 unprovoked attacks over 67 years through 2019, with none resulting in fatalities; the most recent two decades (1999–2019) saw only two non-injurious incidents at netted sites.[34][30] In New South Wales, Australia, the shark meshing program commenced in 1937 amid prior fatalities, including nine deaths on Sydney ocean beaches in the preceding decade. Pre-meshing records indicate recurrent fatal incidents at targeted surf beaches, with historical data showing clusters such as multiple attacks prompting the program's initiation. Post-implementation, meshed beaches have experienced markedly fewer severe outcomes: only one fatal attack recorded at a netted site since 1937, compared to 28 fatalities at unmeshed coastal areas over the same period; early post-deployment data from the first 20 years averaged 0.25 fatalities and 1.1 attacks annually across protected zones.[49][50] Shark attacks overall remain statistically rare, with global unprovoked incidents occurring at rates approximating 1 in 3.7 million beach visits, though historical lethality without intervention was high, often exceeding 20% fatality rates in documented cases. Adjusted historical baselines suggest shark nets have prevented hundreds of potential incidents in high-use areas, accounting for population and visitation growth; for instance, Queensland's analogous program (nets from 1962) saw one fatal attack at controlled beaches versus 27 pre-implementation from 1919–1961. Official records from agencies like the KwaZulu-Natal Sharks Board and NSW Department of Primary Industries cross-verify these trends against incident logs and eyewitness accounts, emphasizing localized reductions at protected sites.Statistical Comparisons Pre- and Post-Implementation
In New South Wales, Australia, Sydney's ocean beaches experienced 9 fatal shark attacks between 1927 and 1937 prior to the deployment of shark nets under the Shark Meshing Program in 1937. From 1937 to 2024, no fatal shark attacks occurred at these netted beaches, representing a complete elimination of fatalities over 87 years despite substantial increases in beach visitation and ocean user numbers.[50] In Queensland, Australia, records indicate 36 shark attacks resulting in 19 fatalities at ocean beaches from 1916 to 1962, before the Shark Control Program—incorporating nets and drumlines—was implemented in 1962 to target high-risk areas. Since implementation, only 2 shark attacks have been documented across the program's monitored beaches over the subsequent 63 years, reflecting a marked decline in both frequency and severity at protected sites.[50] In KwaZulu-Natal, South Africa, Durban beaches recorded 7 fatal shark attacks between 1943 and 1951 prior to the introduction of shark nets in 1952. Post-implementation, zero fatal attacks have occurred at these netted beaches, while unnetted coastal areas continue to see periodic fatalities, highlighting a localized reduction in attack incidence.[50]| Region | Pre-Implementation Period | Attacks/Fatalities | Post-Implementation Period | Attacks/Fatalities |
|---|---|---|---|---|
| Sydney, NSW (Australia) | 1927–1937 | 9 fatal | 1937–2024 | 0 fatal |
| Queensland Beaches (Australia) | 1916–1962 | 36 attacks, 19 fatal | 1962–2025 | 2 attacks |
| Durban, KZN (South Africa) | 1943–1951 | 7 fatal | 1952–present | 0 fatal |
Critiques of Causation and Attribution
Critics contend that observational comparisons between netted and non-netted beaches fail to establish causation due to the inherently low incidence of shark bites, which limits statistical power for detecting meaningful differences. A 2023 analysis of Australian shark-bite data emphasized that even zero bites at protected beaches would not suffice to infer mitigation efficacy, as baseline event rarity precludes robust effect-size detection without large sample sizes or controlled experiments, which are infeasible given ethical and logistical constraints.[7] This methodological hurdle underscores reliance on confounded pre-post implementations, where unmeasured variables like varying beach attendance or patrol visibility obscure attribution to nets alone.[51] Alternative explanations for observed attack declines include natural shark migration patterns and heightened public education on avoidance behaviors, rather than net deterrence. In regions with long-standing programs, such as New South Wales, shark distributions influenced by ocean currents and prey availability may align with seasonal low-risk periods independently of interventions.[52] Moreover, increased swimmer awareness and zoning restrictions post-implementation could account for reductions, as no randomized allocation of nets exists to isolate their impact from these behavioral shifts.[3] Recent surges in Australian shark attacks during the 2010s—rising from an average of 6.5 incidents annually in 1990–2000 to 15 per year thereafter—occur despite entrenched net deployments, challenging direct attribution of safety to the programs.[52] These upticks are linked by researchers to rebounding shark populations following decades of commercial overfishing and subsequent protections, rather than operational shortcomings in nets.[53] Nets typically span only portions of beaches, enabling circumvention via end-swimming or depth variations, with historical data showing 63% of New South Wales ocean beach attacks occurring at meshed sites.[35] Empirical assessments thus yield inconclusive evidence of deterrence, as null hypothesis testing reveals patterns consistent with baseline variability over net-specific causality.[7]Environmental and Ecological Impacts
Bycatch Rates and Non-Target Species
In New South Wales, Australia's Shark Meshing Program deploys gillnets seasonally at 51 beaches, resulting in the entanglement of approximately 200-300 non-target marine animals per season based on recent monitoring. For the 2023/24 season, official records indicate 240 non-target entanglements, comprising 90 rays (including species such as southern eagle rays and cownose rays), 29 turtles (predominantly loggerhead and green sea turtles), 7 marine mammals (such as dolphins), 5 finfish, and 109 sharks not classified as primary targets like white, tiger, or bull sharks. Of these, mortality rates varied, with tag-and-release protocols applied to viable specimens, though exact survival post-release remains unverified in field conditions.[54][21] Target shark captures constitute less than 10% of total entanglements in the program, with rays and turtles forming the majority of bycatch; for instance, rays accounted for over 37% of non-target captures in 2023/24, many of which are protected under Australian biodiversity laws. Loggerhead turtles, listed as endangered, are recurrently entangled, with seasonal peaks during migration periods aligning with net deployments from September to April. Government logs from tag-and-release efforts provide verifiable counts, though underreporting of smaller teleosts or post-release fatalities may occur due to observational limitations.[54][55] In South Africa's KwaZulu-Natal province, the Sharks Board's gillnet program historically captured around 1,600 non-target animals annually alongside 120 target sharks in the 1990s across 40 beaches spanning 44 km of nets, including thousands of teleosts such as tunas and jewfish, as well as rays and cetaceans. Rays dominated numerical bycatch, comprising the largest group, followed by finfish; efforts since the early 2000s to replace nets with drumlines at select sites reduced non-target captures by 47.5%, though gillnets persist at key locations. Target-to-non-target ratios reached 1:8.7 in monitored areas like Richards Bay as of 2025, with over 90% of catches being incidental species, verified through board-maintained catch statistics. Seasonal peaks coincide with bather protection deployments, and while monitoring has stabilized bycatch volumes, transitions to baited hooks have not eliminated gillnet use entirely.[56][29][57]Effects on Shark and Apex Predator Populations
Shark net programs in Australia, such as Queensland's Shark Control Program (SCP) and New South Wales' Shark Meshing Program, have historically removed targeted large-bodied sharks including tiger (Galeocerdo cuvier), bull (Carcharhinus leucas), and great white (Carcharodon carcharias) species, with annual catches of target sharks averaging dozens to low hundreds across regions prior to policy shifts in the 2010s.[58][51] In Queensland, catch-per-unit-effort (CPUE) data indicate localized declines in abundance for these species near netted beaches, reflecting selective removal of mature individuals, though total program captures include many non-target smaller sharks.[59] Since the mid-2010s, operational changes emphasizing tagging and live release of non-aggressive or undersized sharks have reduced mortality rates, with New South Wales reporting only five target shark deaths out of 15 captures in the 2023-2024 season.[60] Population modeling and genetic analyses reveal resilience in shark demographics, with no documented local extinctions attributable to nets despite cumulative removals exceeding thousands over decades. Eastern Australia's great white shark population, estimated at 2,909 to 12,802 individuals (median 5,460) via genetic mark-recapture methods on juveniles, has maintained stable effective breeder numbers over successive years from 2017 to 2021, buoyed by legal protections since 1999 that curtailed commercial fishing impacts.[61][62] Sighting and tagging data further show population recovery trends, with aggregation site abundances increasing post-protection, suggesting immigration from broader oceanic ranges mitigates localized depletions from nets, which affect only a fraction of transient individuals.[63] The selective pressure exerted by nets remains modest relative to historical overfishing, which depleted many apex shark stocks globally prior to protections; shark life history traits—long migrations, low natural mortality, and philopatry to non-netted breeding grounds—confer demographic buffering against sustained population crashes in managed areas.[11] While CPUE reductions signal caution for nearshore cohorts, broader monitoring via acoustic arrays and genetics indicates no collapse, with apex predator roles persisting through regulatory prey dynamics rather than absolute abundance thresholds.[51]Long-Term Ecosystem Consequences
The hypothesis of mesopredator release posits that reductions in apex predators like sharks could lead to expansions in mid-level predators, potentially disrupting lower trophic levels through overpredation. In the context of shark netting programs, such as Queensland's since 1962, empirical catch data indicate declines in certain target species like whaler sharks (Carcharhinus spp.), yet no corresponding surges in mesopredator abundances or explosive increases in their prey have been documented in long-term monitoring. Tiger shark (Galeocerdo cuvieri) catches, for example, have increased, potentially compensating for losses in other apex predators and stabilizing top-down pressure.[64][65] Coastal marine food webs in netted regions appear buffered against pronounced trophic cascades by concurrent human fishing pressures on mesopredators and forage species, which maintain elevated mortality rates independent of shark reductions. Over six decades of data from eastern Australian programs reveal community shifts toward increased functional richness in non-target sharks, but without evidence of systemic instability or verified prey population booms attributable to netting alone. Broader anthropogenic factors, including commercial trawling, contribute more substantially to these dynamics than localized net effects.[66] Sea turtle entanglement in nets contributes to annual mortality rates of approximately 25-30 individuals in New South Wales, primarily loggerheads and green turtles during nesting seasons, with potential localized impacts on recruitment. However, long-term population trajectories remain stable, as evidenced by sustained nesting surveys, owing to offsetting measures like immediate release protocols (with 14 of 19 captured turtles released alive in one assessed period, though post-release survival varies) and dedicated rehabilitation efforts. No empirical records indicate nesting collapses or broader reptilian trophic disruptions from these losses.[67][51] Pre-netting baselines from the early 20th century featured higher apex shark densities without reported ecosystem imbalances beyond natural fluctuations, suggesting inherent resilience in these systems. Post-implementation assessments spanning over 50 years in Queensland and New South Wales confirm no major observed trophic cascades or foundational habitat shifts, such as reef degradation directly linked to shark declines from nets, underscoring that while functional diversity has diminished, outright ecosystem collapse has not materialized.[66][64]Economic and Operational Analysis
Implementation and Maintenance Costs
The Shark Meshing (Bather Protection) Program in New South Wales, Australia, incurs annual costs of approximately AUD 21 million, covering net deployment and servicing at 51 beaches, vessel operations, contractor payments, and administrative oversight by the Department of Primary Industries.[68] These expenditures have trended upward in recent years, influenced by net replacements due to environmental degradation and supplementary technologies such as drone surveillance trials.[69] In Queensland, Australia, the Shark Control Program, which incorporates nets alongside drum lines at key coastal sites, receives substantial government funding, including an additional AUD 88.228 million allocated over four years from 2025 to 2029 for expanded operations and equipment modernization.[6] Base annual operating costs prior to this infusion were lower, with historical parliamentary estimates around AUD 3-5 million, though recent evaluations indicate escalation from program scaling and maintenance demands.[70] The KwaZulu-Natal Sharks Board in South Africa reported ZAR 19.5 million in direct expenditure for shark net maintenance and implementation in the financial year ended 31 March 2024, supporting 13.5 km of netting across 37 beaches, including 1,012 net changes and 8,192 gear services via 3,070 boat launches.[71] This figure excludes broader personnel costs (ZAR 47.88 million total, with ZAR 1.5 million net-specific) and repairs (ZAR 8.07 million), which encompass vessel upkeep and material replacements amid challenges like budget shortfalls and staffing vacancies.[71] Overall program revenue, derived from grants (ZAR 71.27 million) and municipal fees (ZAR 38.04 million), sustains these operations at less than 1% of provincial tourism income.[71]| Cost Component (KZN Sharks Board, 2023/24) | Amount (ZAR) | Description |
|---|---|---|
| Shark Net Maintenance & Implementation | 19,500,000 | Core netting operations and deployment.[71] |
| Net-Related Personnel | 1,500,000 | Staff dedicated to net servicing.[71] |
| Repairs & Maintenance (incl. nets/vessels) | 8,070,000 | Equipment upkeep and replacements.[71] |