Shark barrier

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A shark barrier (otherwise known as a "shark-proof enclosure" or "beach enclosure") is seabed-to-surface protective barrier that is placed around a beach to protect people from shark attacks. Often confused with shark nets, shark barriers form a fully enclosed swimming area that prevents sharks from entering (nets aim to reduce shark populations). [1] Shark barrier design has evolved from rudimentary fencing materials to netted structures held in place with buoys and anchors. Recent designs have used plastics to increase strength, versatility and to reduce the environmental damage of bycatch.

Contents

Shark barriers vs shark nets

Shark barriers are commonly mistaken for shark nets. [1] 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. [2]

Netting 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. [3] Shark nets have been heavily criticized in the media for the environmental effects of bycatch. [4] 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. [5]

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. [6]

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 venomous jellyfish.

Shark barriers are often made out of netting; held in place by a system of piles, anchors and buoys. Netted barriers are susceptible to damage from strong ocean forces and so are generally limited to sheltered bays and beaches and favourable seasons and weather conditions. [2]

Following the controversial Western Australian shark cull, the Western Australian State Government trialled a netted shark barrier in Dunsborough in 2013/14 and allocated funds for a new shark barrier to be installed in Busselton. Environmentally friendly shark barriers have also been developed in Western Australia in response to a string of fatal shark attacks on the WA coastline. [7]

Hong Kong

In Hong Kong, after three swimmers were killed by sharks in 1995, the government installed shark nets on gazetted beaches. Unlike the long-line and gill-net designs commonly used in Australia and South Africa, these are permanent installations and work as barrier nets. There have been zero fatalities since installation in 1995. As of 2014, shark nets are in place at 32 Hong Kong beaches. [8]

Barrier 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". [9]

Réunion Island

On Réunion Island following 19 shark attacks since 2011, including 7 fatalities [10] "Smart" drumlines are used, in conjunction with shark nets. [11] In 2015 the island, supported by France, spent two million Euros on two shark-proof fences / shark enclosures on the west of the island. The fences are strung below the water's surface and cost the region a million Euros a year to maintain. [12] A 610m net, protecting a bathing area of 84,000sq m, has been installed off Boucan Canot and a 500m net has been installed off Roches Noires. [13] The shark nets are subject to damage from heavy swells. [13] On the 27 August 2016 a surfer lost an arm and a foot from a shark attack whilst surfing within one of the share enclosures. It was reported that at the time of the attack there was a two-meter hole in the nets, most probably caused by the swell. [14]

Environmentally-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. [2]

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). [15] [16]

Another barrier design has been produced from Form Designs Australia, who were also involved in the trial of the Eco Shark Barrier. [17] 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. [18] The structural performance of this design could not be assessed although it potentially improves the current system. [18]

The general response by the public towards the environmentally friendly shark barrier at Coogee was positive (95%). [15] 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. [18]

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. [19] 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. [20] 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". [20]

Related Research Articles

<span class="mw-page-title-main">Shark attack</span> Attack on a human by a shark

A shark attack is an attack on a human by a shark. Every year, around 80 unprovoked attacks are reported worldwide. Despite their rarity, many people fear shark attacks after occasional serial attacks, such as the Jersey Shore shark attacks of 1916, and horror fiction and films such as the Jaws series. Out of more than 500 shark species, only three of them are responsible for a double-digit number of fatal, unprovoked attacks on humans: the great white, tiger, and bull. The oceanic whitetip has probably killed many more castaways, but these are not recorded in the statistics.

<span class="mw-page-title-main">Shark net</span> A submerged barrier that protects swimmers from shark attacks

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. 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. Shark nets do not create an exclusion zone between sharks and humans, and are not to be confused with shark barriers.

<span class="mw-page-title-main">Coogee, New South Wales</span> Suburb of Sydney, Australia

Coogee is a beachside suburb in the Eastern Suburbs of Sydney, in the City of Randwick. Coogee is located 8 kilometres south-east of the Sydney central business district, in the state of New South Wales, Australia.

<span class="mw-page-title-main">Cetacean bycatch</span> Accidental capture of porpoises, whales and dolphins

Cetacean bycatch is the accidental capture of non-target cetacean species such as dolphins, porpoises, and whales by fisheries. Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.

<span class="mw-page-title-main">Turtle excluder device</span> Device for freeing sea turtles from bycatch

A turtle excluder device (TED) is a specialized device that allows a captured sea turtle to escape when caught in a fisherman's net.

<span class="mw-page-title-main">Wedding Cake Island</span>

Wedding Cake Island is an island located approximately one kilometre (0.6 mi) east of Coogee Beach, Sydney, Australia in the Tasman Sea. The island protects the beach from most swells. The island is also known as Lemo's Island.

<span class="mw-page-title-main">Drift netting</span> Fishing technique

Drift netting is a fishing technique where nets, called drift nets, hang vertically in the water column without being anchored to the bottom. The nets are kept vertical in the water by floats attached to a rope along the top of the net and weights attached to another rope along the bottom of the net. Drift nets generally rely on the entanglement properties of loosely affixed netting. Folds of loose netting, much like a window drapery, snag on a fish's tail and fins and wrap the fish up in loose netting as it struggles to escape. However, the nets can also function as gill nets if fish are captured when their gills get stuck in the net. The size of the mesh varies depending on the fish being targeted. These nets usually target schools of pelagic fish.

<span class="mw-page-title-main">Greenmount Beach</span>

Greenmount Beach is a beach located in Coolangatta on Queensland's Gold Coast in Australia.

<span class="mw-page-title-main">Environmental issues in Australia</span>

Environmental issues in Australia describes a number of environmental issues which affect the environment of Australia. There are a range of such issues, some of the relating to conservation in Australia while others, for example the deteriorating state of Murray-Darling Basin, have a direct and serious effect on human land use and the economy.

<span class="mw-page-title-main">Shelly Beach (Manly)</span>

Shelly Beach is a beach located in Manly, a suburb of Sydney, New South Wales, Australia. It is adjacent to North Head and Fairy Bower. Shelly Beach is a western facing beach on the eastern coast of Australia.

<span class="mw-page-title-main">Grey nurse shark conservation</span> Conservation management of grey nurse sharks

One of the first shark species to be protected was the grey nurse shark. The biology, distribution and conservation of this species are dealt with in the following paragraphs with a main focus on Australia as it was here it first became protected.

<span class="mw-page-title-main">Environmental impact of fishing</span>

The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of industrial fishing on other elements of the environment, such as bycatch. These issues are part of marine conservation, and are addressed in fisheries science programs. According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. There is a growing gap between the supply of fish and demand, due in part to world population growth.

Dolphin-safe labels are used to denote compliance with laws or policies designed to minimize dolphin fatalities during fishing for tuna destined for canning.

A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks. They are typically deployed near popular swimming beaches with the intention of reducing the number of sharks in the vicinity and therefore the probability of shark attack. Drum lines are often used in association with shark nets, which results in shark mortality. However SMART drum lines can be used to move sharks, which greatly reduces shark and bycatch mortality. The use of drum lines has been successful in reducing shark attacks in the areas where they are installed. The topic of shark culling became an international controversy and sparked public demonstrations and vocal opposition, particularly from environmentalists, animal welfare advocates and ocean activists.

Angourie Point is a surf break in the small township of Yamba on the north coast of New South Wales, Australia. Angourie Point is an exposed point break that has consistent surf, and surf offshore winds are from the southwest. Groundswells and wind swells are good and the best swell direction is from the east or south east.

<span class="mw-page-title-main">Western Australian shark cull</span> Former policy to reduce sharks attacks

The Western Australian shark cull is the common term for a former state government policy of capturing and killing large sharks in the vicinity of swimming beaches by use of baited drum lines. The policy was implemented in 2014 to protect human swimmers from shark attack following the deaths of seven people on the Western Australian coastline in the years 2010 to 2013. National public demonstrations opposing the policy attracted international attention to the issue. In September 2014 the seasonal setting of drum lines was abandoned following a recommendation made by the Western Australian Environment Protection Authority. From December 2014 to March 2017, the special deployment of drum lines was permitted in cases where sharks were deemed to present a serious threat to public safety. This policy allowed the government of Western Australia to kill "high-hazard" sharks it found to be a threat to humans; the policy was criticized by senator Rachel Siewart for damaging the environment. In March 2017 the use of drum lines was abandoned by the newly elected West Australian state government. In August 2018 following continual shark attacks the West Australian state government reversed their position and announced a 12-month trial of "SMART" drumlines along Western Australia's South West coast, near Gracetown.

<span class="mw-page-title-main">Middleton Beach shark barrier</span>

Middleton Beach shark barrier, also referred to as the Albany shark barrier and the Ellen Cove shark barrier, is a shark barrier to prevent sharks entering the main swimming area at Ellen Cove at the southern end of Middleton Beach, a popular swimming beach in Albany in the Great Southern region of Western Australia.

<span class="mw-page-title-main">Shark attack prevention</span> Means to reduce the risk of shark attack

There are a range of shark attack prevention techniques employed to reduce the risk of shark attack and keep people safe. They include removing sharks by various fishing methods, separating people and sharks, as well as observation, education and various technology-based solutions.

<span class="mw-page-title-main">Shark culling</span> Sanctioned killings of sharks

Shark culling is the deliberate killing of sharks by government authorities, usually in response to one or more shark attacks. The term "shark control" is often used by governments when referring to culls. Shark culling has been criticized by environmentalists, conservationists and animal welfare advocates—they say killing sharks harms the marine ecosystem and is unethical. Government officials often cite public safety as a reason for culling. The impact of culling is also minor compared to bycatch with 50 million sharks caught each year by the commercial fishing industry.

<span class="mw-page-title-main">Valerie Taylor (diver)</span> Australian underwater photographer

Valerie May Taylor AM is a conservationist, photographer and filmmaker, and an inaugural member of the diving hall-of-fame. With her husband Ron Taylor, she made documentaries about sharks, and filmed sequences for films including Jaws (1975).

References

  1. 1 2 Meerman, Ruben (7 March 2002). "Shark nets". Abc.net.au. Retrieved 26 November 2021.
  2. 1 2 3 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.
  3. ↑ "NSW Shark Meshing publications | NSW Department of Primary Industries". www.dpi.nsw.gov.au. Retrieved 20/09/14
  4. ↑ Dudley, S and Cliff, G. "Reducing the environmental impact of shark-control programs: a case study from Kwa-Zulu-Natal, South Africa". Marine and Freshwater Research, 2011. vol.62, pp. 700-709
  5. ↑ "Fact File: Protecting people from shark attacks". Abc.net.au News. 22 December 2013. Retrieved 26 November 2021.
  6. ↑ "Trigger Bros Surfboards – Phils Ramblings – Shark Nets". Blog.triggerbrothers.com.au. Retrieved 26 November 2021.
  7. ↑ [ dead link ]
  8. ↑ "Safety at the beach". Gov.hk. Aug 2014. Retrieved 2014-09-14.
  9. ↑ 76 Chung Hom Kok Rd. "Google Maps" . Retrieved 2013-09-11.
  10. ↑ Suarez, Alexandra (30 August 2016). "Surfer Shark Attack On Reunion Island Leaves Man Without Arm And Foot". International Business Times . Retrieved 26 November 2021.
  11. ↑ "Surrounded: Island of the Sharks (Part 2)". Video.vice.com. Retrieved 26 November 2021.
  12. ↑ Magazine, Smithsonian; Schuetze, Christopher F. "Why Is This Indian Ocean Island a Hot Spot for Shark Attacks?". Smithsonian Magazine. Retrieved 26 November 2021.
  13. 1 2 "Subscribe to The Australian". Dsf.newscorpaustralia.com. Retrieved 26 November 2021.
  14. ↑ "Shark Attack Number 19 and All is Not Well on Reunion Island - Magicseaweed". Magicseaweed.com. Retrieved 26 November 2021.
  15. 1 2 "Summary of Agenda to be presented to the Ordinary Council Meeting to be Held on Thursday, 8 May 2014 at 7:00 PM" (PDF). City of Cockburn. 2014. Retrieved 5 October 2014.
  16. ↑ "Eco Shark Barrier". Ecosharkbarrier.com.au. Retrieved 26 November 2021.
  17. ↑ "Global Marine Enclosures". Global Marine Enclosures. Retrieved 26 November 2021.
  18. 1 2 3 "Department of the Premier and Cabinet". Wa.gov.au. Retrieved 26 November 2021.
  19. ↑ "Shark management". Archived from the original on 2016-11-29. Retrieved 2016-11-28.
  20. 1 2 "Ballina shark problem: How an eco barrier became an 'environmental disaster'". Abc.net.au. Retrieved 28 November 2016.
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