Shark attack prevention
Environmental groups have voiced concern over the impact of reduced shark numbers on ocean ecosystems and the problem of by-catch of other marine life, particularly endangered species.
[8][19][13] The current net program in New South Wales has been described as being "extremely destructive" to marine life;[20] it has also been called "outdated and ineffective".
[22] Shark barrier design has evolved from rudimentary fencing materials to netted structures held in place with buoys and anchors.
When deployed in sheltered areas shark barriers offer complete protection and are seen as a more environmentally friendly option as they largely avoid bycatch.
[25] A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks.
Drum lines were first deployed to protect users of the marine environment from sharks in Queensland, Australia in 1962.
[30] Drum line programmes that involve culling have been criticized for being environmentally destructive and speciesist, and have sparked public demonstrations and vocal opposition, particularly from environmentalists, animal welfare advocates and ocean activists.
[34] However environmental damage from drumlines is minor compared to commercial fishing[15][16] with estimates of 50 million sharks caught unintentionally each year.
[35] This technique has also been successfully demonstrated in the NSW North Coast SMART drumline trial (Australia) where 99% of targeted sharks and 98% of other animals caught were released alive.
[38] Whilst it is noted the Shark Shield technology does not work in all situations[36][39][37] and divers have been attacked whilst wearing Shark Shield,[38][40] modelling research from Flinders University in 2021 indicated that the proper use of personal electronic deterrents is an effective way to prevent future deaths and injuries.
[44] Acoustic tags transmit pulses which are detected by underwater listening stations when the sharks swim close by, typically within 500 metres.
[2] However visibility issues with water clarity can be a problem particularly with aerial patrols, which have been found to identify less than 20% of sharks present.
[49] Other examples of personal shark protection technologies include wearing interruption patterned or camouflage wetsuits,[50] magnetic repellents incorporating a small magnet in a band worn on the wrist or ankle,[48] acoustic repellents that mimic the sound of orcas[38] and changing surf board colours.
Only Shark Shield’s Ocean Guardian Freedom+ Surf showed measureable results, with encounters reduced from 96% to 40%.
Rpela (electrical repellent technology), SharkBanz bracelet & SharkBanz surf leash (magnetic shark repellent technology) and Chillax Wax (semiochemical) showed no measureable effect on reducing shark attacks.
[57] In September 2015, a shark sonar created by Ric Richardson was tested in Byron Bay, Australia.
[62][63] The technique of setting drum lines is also used in Queensland and New South Wales, where they have been used in association with shark nets.
[67] Following 11 shark attacks along the NSW north coast between 2014 and 2016, including two fatalities,[68] Shark nets and SMART drumlines were deployed in December 2016 to cover five additional beaches along the NSW North Coast in a two-year trial.
[77] In South Australia, spotter planes and a small number of patrolled swimming beaches are the only methods used to mitigate the risk of shark attack.
On 6 February 2014, Port Lincoln tuna "baron" Hagen Stehr expressed his support for the Western Australian shark cull.
He also stated that his business' spotter planes had observed increases in great white shark numbers off the west coast of Eyre Peninsula.
The region's shark attack statistics primarily reflect the effectiveness of netting, as drum lines were only introduced recently, following their successful use for over 40 years in Queensland, Australia.
"[81] The presence of nets has greatly reduced the number of shark attacks along Natal beaches.
Drum lines set in the region are baited with 500 grams of meat per hook and are believed to only attract sharks from several hundred metres away.
Pressure from the tourism industry to reinstate nets during the sardine run has previously proven "disastrous", resulting in large numbers of shark and dolphin mortalities.
[19] Environmental groups say KwaZulu-Natal's "shark control" program is unethical and harms the marine ecosystem.
[10][84] The study concluded that the culls "do not appear to have had measurable effects on the rate of shark attacks in Hawaiian waters".
[85] Borg detailed the debates between the study's authors and other scientists who argued that the experiences of South Africa's KwaZulu-Natal Shark Board[86] demonstrated the effectiveness of the culling.
[25] The protective nets / shark enclosures at the two beaches have a total length of just under 1 mile and are subject to damage from heavy swell.
On 27 August 2016 a surfer lost an arm and a foot from a shark attack while surfing within one of the enclosures.
