Shark net

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. Shark nets used are gillnets which is a wall of netting that hangs in the water and captures the marine animals by entanglement, however only around 10% of catch is the intended target shark species.^[1][2] 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.^[3] 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.^[4] 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 offer complete protection but work on the principle of "fewer sharks, fewer attacks". They aim to reduce occurrence via shark mortality. Shark nets such as those in New South Wales are designed to entangle and capture sharks that pass near them.^[5] 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.^[6][7][8] However a 2019 study argued this conclusion overlooks key factors.^[9] 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.^[10]

Shark nets have been criticized by environmentalists, conservationists and animal rights activists — they say shark nets are unethical and harm the marine ecosystem.^{[11][12][5][13][14][15]} They also argue there is no science showing that nets make the ocean safer for people.^[5]