Shark barriers vs shark nets
Shark barriers are commonly mistaken for shark nets. While they have the same objective of protecting swimmers, they have different characteristics as follows:Exclusion method
Shark barriers work on the principle of excluding sharks from a designated swimming area. Shark barriers form an "underwater fence" from seabed-to-surface, beach-to-beach. Shark barriers are seen as a more environmentally friendly option as they largely avoid bycatch, however they cannot protect the same sized area as culling methods.McPhee, D. “Likely effectiveness of netting or other capture programs as a shark hazard mitigation strategy in Western Australia” Fisheries Occasional Publication, 2012. no.108, August. Available at: www.fish.wa.gov.au.Culling method
Shark (meshing) nets operate as a catch-and-kill strategy to reduce the incidence rate of shark attack by reducing the local population size of sharks. Shark nets have been heavily criticized in the media for the environmental effects of bycatch. They also do not provide a fully enclosed swimming area as sharks can swim above, below or around them.Suitability for surf beaches
Shark barriers are not generally used on surf beaches because they usually disintegrate in the swell and so are normally constructed only around sheltered areas such as harbour beaches. Where there are surf conditions at Hong Kong beaches, the swell is "typically small". Even if they were in place at surf beaches, they would not protect surfers who go some distance from shore. The shark nets are more suitable for surf beaches as they can be anchored beyond the deepest sandbank and can be easily taken out of the water whenever any big swell is forecast.Australia
Shark barriers are currently used in Queensland, New South Wales, South Australia and Western Australia. Many of the shark barriers used in Queensland also feature protection from venomousHong Kong
InBarrier net design
The Hong Kong nets are generally 35 mm square on the surface 2 m and 100 mm square thereafter. They are suspended off 225 mm HDPE pipe or BL14 Marine Float Lines, and anchored strongly to resist the many typhoons and waves up to 10 m. They are anti-fouled, and spend an average of 9 months a year in the water. An average net enclosure would be 500 m long and either semi-circular or rectangular in shape. They are diver-inspected a minimum of two times a week, and independent verification is required. They also exclude floating refuse, and clearly define the swimming area. They can be clearly picked out on Google Earth - at 22^14'38" North, 114^11'26" East, see "Repulse Bay".Réunion Island
OnEnvironmentally-friendly shark barriers
Development in materials has led to innovative plastic barrier designs that prevents marine bycatch. The rigid barrier panels allow fish and small marine creatures to swim through unobstructed, while restricting larger marine predators. New materials also potentially increase the scope of use beyond calmer waters. The first environmentally friendly shark barrier was trialled at Coogee Beach in Western Australia. The trial ran for four months between December 2013 and April 2014. Since this trial, new designs have emerged, including a new barrier from local company Eco Shark Barriers which was purchased by the City of Cockburn in 2014 (currently operational at Coogee Beach). Another barrier design has been produced from Form Designs Australia, who were also involved in the trial of the Eco Shark Barrier. The "Bionic Barrier" was designed to overcome some of the issues that arose in the trial, including increasing flexibility with hinge panels to adapt to tides and swell. The structural performance of this design could not be assessed although it potentially improves the current system. The general response by the public towards the environmentally friendly shark barrier at Coogee was positive (95%). It was also noted that the barrier acted as a form of artificial reef or FAD (fish attracting device) which was seen as a positive point of interest for the beach. In 2016 trials of two eco friendly shark barriers in NSW, Australia were discontinued after both manufacturers were unable to safely and effectively install the barriers. Installation of the "eco barrier" by Eco Shark Barriers at the popular surf break Lighthouse Beach, on the New South Wales far north coast, had been stopped by the amount of sand movement which made it impossible for divers to install the moorings. Another kind of barrier, the Aquarius Barrier, designed by a different company, Global Marine Enclosures, was installed at Seven Mile Beach, Lennox Head, about 10 km up the coast. Head-high swell came over the course of a weekend and the barrier started to fray and disintegrate. Plastic from the barrier was scattered for kilometres. Locals were referring to the Aquarius Barrier as an “environmental disaster”.References
{{Reflist Protective barriers Shark attack prevention