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. 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. However a 2019 study argued this conclusion overlooks key factors. 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 approximately A$20,000 per beach per year. Shark nets have been criticized by environmentalists, conservationists and animal rights activists — they say shark nets are unethical and harm the marine ecosystem. They also argue there is no science showing that nets make the ocean safer for people. Only around 10% of catch in shark nets is the intended target shark species. 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. 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.
History 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. Nets were first deployed off certain beaches in KwaZulu-Natal (formerly Natal), South Africa, in 1952. 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. No shark attacks have occurred since their removal. As of 2018, shark nets are used in New South Wales, Queensland and KwaZulu-Natal. 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. The New South Wales Green party said they wanted all shark nets removed.
Effectiveness Ongoing shark control programs have been very successful in reducing the incidence of shark attack at the protected beaches. 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. 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. However, the net program in New South Wales has been called "outdated and ineffective" by environmental groups; they argue that shark nets do not protect swimmers. 65% of shark attacks in New South Wales occurred at netted beaches.
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