SHARK MITIGATION SCIENCE
Accessible Research, Safer Waters
Magnetic mitigation science
Magnetic mitigation aims to deter sharks. These come in the form of magnets used as deterrents/repellents. Examples of magnets used as barriers/nets can be found on the Barriers & enclosures page.
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Studies that assess magnetic deterrents/repellents generally can test whether these products can deter sharks (as opposed to testing the ability to detect sharks or test bite resistance, for example). This is because magnetic mitigation works at a short range (within approximately 3m) and studies can be designed with control trials (e.g., no/fake magnet present), which gives researchers the ability to compare the deterrent and control.
The research
This study assesses the ability of strong neodymium magnets and pulsed magnetic fields (PMFs) to deter captive sand tiger sharks (Carcharias taurus). The magnet did not affect shark behaviour. The PMFs affected some of the sharks behaviours. Results suggest that strong magnets may not be an adequate sand tiger shark deterrent, but PMFs show promise.
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Polpetta, M., Piva, F., Gridelli, S. and Bargnesi, F., 2021. Behavioural responses in the sand tiger shark (Carcharias taurus) to permanent magnets and pulsed magnetic fields. Marine Biology Research, 17(1), pp.41-56.
​Juvenile lemon sharks (Negaprion brevirostris) were temporarily blinded and exposed to magnetic fields to assess if shark behaviours changed. Magnets increased avoidance distance, visit frequency before entrance to the magnetic zone and total visits and entrances.​ Murky water maximised magnetic repellent effectiveness.
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O'Connell, C.P., Guttridge, T.L., Gruber, S.H., Brooks, J., Finger, J.S. and He, P., 2014. Behavioral modification of visually deprived lemon sharks (Negaprion brevirostris) towards magnetic fields. Journal of experimental marine biology and ecology, 453, pp.131-137.
This study assesses the deterrent ability of C8 Barium-Ferrite (empirically, BaFe12O19) permanent magnets on southern stingrays (Dasyatis americana) and nurse sharks (Ginglymostoma cirratum). Both species exhibited more avoidance behaviours around the magnets and more feeding behaviours around the non-magnet section of the experiment. Both species were sensitive to the magnetic field and were deterred from baited areas containing magnets.
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O’Connell, C.P., Abel, D.C., Rice, P.H., Stroud, E.M. and Simuro, N.C., 2010. Responses of the southern stingray (Dasyatis americana) and the nurse shark (Ginglymostoma cirratum) to permanent magnets. Marine and Freshwater Behaviour and Physiology, 43(1), pp.63-73.
Five different deterrents were tested on white sharks - the Shark Shield Pty Ltd [Ocean Guardian] Freedom+ Surf (electric), Rpela (electric), SharkBanz bracelet (magnetic), SharkBanz surf leash (magnetic), and Chillax Wax (smell-based). Authors compared the number of baits taken, number of passes, number of reactions and the distance between control (devices switched off) and treatment (devices switched on) trials. The Freedom + Surf was the most effective deterrent, reducing the proportion of baits taken from 96% (control) to 40% (device switched on), and increasing the pass distance from 1.6 ± 0.1 m (control board) to 2.6 ± 0.1 m (device switched on). No other deterrents (including the magnetic deterrents) had a measurable affect on white shark behaviour.
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Huveneers, C., Whitmarsh, S., Thiele, M., Meyer, L., Fox, A. and Bradshaw, C.J., 2018. Effectiveness of five personal shark-bite deterrents for surfers. PeerJ, 6, p.e5554.