1. History

Shark net meshing was thought up by the New South Wales Fisheries in 1935, after a decade and a half of relentless Shark attacks off Sydney beaches. In March 1935, for example, two people — one at North Narrabeen and one at Maroubra — were killed by great white sharks in a single week. The meshing was never designed to enclose a piece of water — even back then, they knew barrier nets would never survive a surf zone. Instead, it was designed to catch large dangerous 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, quite a number of which are released alive.^[1]

Nets were also first deployed off certain beaches off KwaZulu-Natal (KZN, formerly Natal) South Africa, in 1952.^[2]

As of 2018, shark nets are currently used in New South Wales, Queensland and KwaZulu-Natal.^[3][4][5] 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.^[6][7] The New South Wales Green party said they wanted all lethal nets to be removed.^[7]

2. Effectiveness of Shark Nets

Ongoing shark control programs have been somewhat successful in reducing the incidence of shark attack at the protected beaches.^[2][8] In the years from 1900 to 1937, 13 people were killed off New South Wales surf beaches by sharks; 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.^[1]

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.^[9]

However, the net program in New South Wales has been called "outdated and ineffective".^[6] It has been argued that shark nets do not protect swimmers.^[10] 65% of shark attacks in New South Wales occurred at netted beaches.^[11]

3. Environmental Impact

Shark nets result in incidence of bycatch, including threatened and endangered species like sea turtles, dugongs, dolphins and whales. In Queensland in the 2011/12 summer season there were 700 sharks caught, 290 above 4 metres in shark nets and drum lines.^[12]

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.^[1]

New South Wales and Queensland also utilize acoustic pingers attached to the nets to reduce bycatch of dolphins, whales and other marine mammals.^[13] Use of the pingers has been shown to significantly reduce marine mammal bycatch.^[14]

The current net program in New South Wales has been described as being "extremely destructive" to marine life.^[15] Between September 2017 and April 2018, more than 403 animals were killed 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.^[6] Between 1950 and 2008, 352 tiger sharks and 577 great white sharks were killed in the nets in New South Wales — also during this period, a total of 15,135 marine animals were killed in the nets.^[3] More than 5,000 marine turtles have been caught on the nets.^[11] The New South Wales government prohibits people from rescuing entangled animals — this prohibition has been called "heartless and cruel".^[16]

In a 30-year period, more than 33,000 sharks have been killed in KwaZulu-Natal's shark net program.^[5] During the same 30-year period, 2,211 turtles, 8,448 rays, and 2,310 dolphins were killed in KwaZulu-Natal's shark net program.^[5]

Animal welfare groups suggest alternatives such as surf lifesaving patrols, public education on shark behaviour, radio signals, sonar technology and electric nets.

However, it should be noted that bycatch from shark nets is minor compared to bycatch from other activities. For example, Australia's commercial shark fishing industry is taking over 1200 tonne of shark out of our various fisheries each year: everything from gummy shark to mako, and very likely a few white sharks as well. The NSW prawn trawling industry alone results in 64 tonne of shark as bycatch each year. Six percent of what's caught in the tuna longline fisheries in northern Australia is shark.^[1]

4. Cost

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.^[17] For the 51 beaches protected,^[17] this represents a financial cost of approximately AUD$20,000 per beach per year.

5. Australia

Graph of sharks caught in Queensland's Shark Control Program (by type) July 1997- June 2014. https://handwiki.org/wiki/index.php?curid=1272973

In New South Wales, Australia , 51 beaches are netted.^[18] 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.^[19] From 1950 to 2008, hundreds of great white sharks and tiger sharks were killed in the nets in New South Wales.^[3]

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.^[12] Since 1997, the program kills 500-900 sharks annually, including several shark species of conservation concern. They include the following:

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.^[25] Drum lines were installed at beaches around the island at the time.^[26]

6. South Africa

In South Africa , shark nets are installed at numerous beaches in KwaZulu-Natal by the KwaZulu-Natal Sharks Board. Shark nets have been installed in KwaZulu-Natal since the 1950s.^[5] More than 30,000 sharks have been killed in KwaZulu-Natal's nets.^[5] KwaZulu-Natal's shark net program has been called "archaic".^[5]

The content is sourced from: https://handwiki.org/wiki/Engineering:Shark_net