This footage shows the Stingray, that the previous post I posted didnt, that was almost dead lying at the bottom of the ocean in Bondi near the dead shark on Friday 21/11/14 suffering a prolonged agonising death. In 1992 Valerie and Ron Taylor successfully tested the Shark Shield against the Great White Sharks and made the recommendation to remove all of the nets and to replace them with these electronic devices that was quite obviously ignored. Valerie and her now deceased husband (2012) Ron Taylor filmed a documentary to show how the deterrents worked. I am quoting from the Shark Shield Wikipedia testing for your information with the link below some of the quotes from the report: ...The original SharkPOD was tested for eight years off Dyer Island with mainly great white sharks, and was the first electronic device that was proven successful in deterring sharks when tested by Ron Taylor and Valerie Taylor in 1992 on sharks in Australia and South Africa with positive results—they made a documentary about it called Shark POD. Extensive field testing was conducted on the Shark Shield off Neptune Island, South Australia, using the FREEDOM4 and subsequently the FREEDOM7 by renowned wildlife documentary videographer, Ian “Shark” Gordon. Gordon personally tested the effectiveness of the device on a variety of particularly aggressive shark species, including black-tipped reef sharks, mako sharks, and great white sharks, by setting a tuna bait to attract the sharks while he was wearing a Shark Shield, and then videoing their hasty retreat as they approached within meters of the activated device.[8]... All chondrichthyans have highly sensitive electrical receptors called the “Ampullae of Lorenzini” located in their snouts. These tiny gel filled sacs sense electrical current from prey at very close distances, typically less than one meter. They use these short range sensors when feeding or searching for food. They do not use electrical receptors to track animate objects over long distances; other senses such as audition and olfaction are the primary drivers.[3][4] Shark Shield devices create an electrical waveform that creates an unpleasant sensation impacting the shark’s ‘Ampullae of Lorenzini’. When the shark comes into proximity of the electrical waveform (a few meters in diameter) it experiences uncontrollable muscular spasms causing it to flee the area.[5][6] The field is projected from two electrodes, which create an elliptical field that surrounds the user. Both electrodes must be immersed in the water for the field to be created. Research conducted by The South African National Space Agency (SANSA) in 2012 estimated the Shark Shield electrical field to be approximately four to five meters in diameter.[7] While sharks are attracted to electromagnetic pulses produced by potential prey animals, the electronic field emitted by the Shark Shield does not attract sharks to the device and therefore would not increase the risk of attracting sharks to the vicinity of the user. A sharks sensory organs are acutely sensitive to low-voltage gradients (> 5 nVcm), enabling them to detect very low-frequency electronic fields of between 1–8 Hz at short range, after which the other senses (sight, chemoreception and mechanoreception) aid the shark in capturing its prey.[3][4] The range at which an electronic shark deterrent emits a field that is the equivalent of a prey-like stimulus (approx 1–100 nV/cm) is much further than their short range detection facilitates. Should a shark approach the device, the strength of the electric field will get stronger the closer it gets, and will soon cause the shark extreme discomfort, forcing it to turn away. Scientific studies modelling this effect show that the output produced at a 3 meter distance is far greater than that produced by prey, and would drop off significantly beyond a 6 m radius, where it would be beyond the short range detection ability of a shark.... en.wikipedia.org/wiki/Shark_Shield
Posted on: Mon, 24 Nov 2014 09:22:38 +0000
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