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Evaluation of Neodymium-Iron-Boride Magnets as Selective Shark Repellents on Demersal Longlines Michael M. Herrmann, July 17, 2006.

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Presentation on theme: "Evaluation of Neodymium-Iron-Boride Magnets as Selective Shark Repellents on Demersal Longlines Michael M. Herrmann, July 17, 2006."— Presentation transcript:

1 Evaluation of Neodymium-Iron-Boride Magnets as Selective Shark Repellents on Demersal Longlines Michael M. Herrmann, July 17, 2006

2 Introduction What we know to date: Materials Geometries Tonic Immobility responses Effects on Fish Rigging Preliminary results on demersal lines

3 Materials NIB Neodymium-iron-boride sinter with Ni or Zn plate Nd 2 Fe 4 B (Empirical) Highest flux per size (BHmax is > 50 MGOe) “N50” Poor corrosion resistance Ceramics Barium-ferrite material BaFe 12 O 19 (Empirical) Cheap and heavy, largest flux area SmCo Samarium-cobalt sinter SmCo 5, Sm 2 Co 17 (Empirical) Corrosion-resistance and expensive (BHmax ~43 MGOe)

4 Materials NIB Neodymium-iron-boride sinter with Ni or Zn plate Nd 2 Fe 4 B (Empirical) Highest flux per size (BHmax is > 50 MGOe) “N50” Poor corrosion resistance Ceramics Barium-ferrite material BaFe 12 O 19 (Empirical) Cheap and heavy, largest flux area SmCo Samarium-cobalt sinter SmCo 5, Sm 2 Co 17 (Empirical) Corrosion-resistance and expensive (BHmax ~43 MGOe)

5 Materials NIB Neodymium-iron-boride sinter with Ni or Zn plate Nd 2 Fe 4 B (Empirical) Highest flux per size (BHmax is > 50 MGOe) “N50” Poor corrosion resistance Ceramics Barium-ferrite material BaFe 12 O 19 (Empirical) Cheap and heavy, largest flux area SmCo Samarium-cobalt sinter SmCo 5, Sm 2 Co 17 (Empirical) Corrosion-resistance and expensive (BHmax ~43 MGOe)

6 Tonic Immobility Assay Fields greater than 50G will terminate TI at a distance of 0.0 – 0.3m

7 Responses to Magnets - Sharks Free-swimming sharks will turn off of a buried magnet

8 Responses to Magnets - Sharks Diminishing response with continuing exposure Magnetosense appears to be “switchable” High olfactory stimulation overrides magnetosense Magnet at d=0.0m to shark, no response

9 Responses to Magnets - Sharks Diminishing response with continuing exposure Magnetosense appears to be “switchable” High olfactory stimulation overrides magnetosense Diminishing response

10 Responses to Magnets - Sharks Diminishing response with continuing exposure Magnetosense appears to be “switchable” High olfactory stimulation overrides magnetosense Essentially no response

11 Responses to Magnets - Sharks Spotted wobbegongs (O. maculatus) do not appear to respond to NIB and BaFerrite magnets

12 Responses to Magnets - Teleosts IATTC Achotines, Panama, July 2005 Feeding preference trials in Thunnus albacares (magnetoreceptive) University of Miami, RSMAS, August 2005 Feeding preference trials in Rachycentron canadum Feeding behavior is not affected by the presence of NIB magnets

13 Responses to Magnets - Teleosts IATTC Achotines, Panama, July 2005 Feeding preference trials in Thunnus albacares (magnetoreceptive) University of Miami, RSMAS, August 2005 Feeding preference trials in Rachycentron canadum Feeding behavior is not affected by the presence of NIB magnets

14 Selecting a Geometry Optimum geometry is pyramidal stacking

15 Selecting a Geometry Optimum geometry is pyramidal stacking Highest measurable flux at tips

16 Selecting a Geometry Optimum geometry is pyramidal stacking Highest measurable flux at tips 9,000G - 9,300G

17 Practical Rigging 1”x1” cylinder with 3/16” center bore is preferred Shape the magnetic flux to encompass the bait

18 Shaping the Flux 1”x1” cylinder with 3/16” center bore is preferred Shape the magnetic flux to encompass the bait Steel tophat

19 Shaping the Flux

20 Rigging

21 2” Steel tophat 1” NIB Sleeve 16/0 hook

22 Possible Galvanic Cell Steel with cold galvanizing compound Copper sleeve Passive Ni-plate NIB Mild steel tophat

23 Rigging NIB

24 Setting the Demersal Line 1 demersal line with 15 16/0 circle hooks Same type of bait L-P Hook Event Timers 24 hour rebait periods Lines checked every 4 hours Alternating magnets and controls

25 Setting the Demersal Line

26

27 Preliminary Results N48 square blocks, 67 hour total soak time NOVEMBER ”x2”x1/8” square N48

28 Preliminary Results N48 square blocks, 67 hour total soak time NOVEMBER ”x1”x1/8” square N48 High flux, clumsy shape

29 Preliminary Results N48 square blocks, 67 hour total soak time No sharks captured on treatment hooks NOVEMBER 2005

30 Preliminary Results N48 mini-cylinders, 24 hour total soak time FEBRUARY 2006 – UNDERSIZED MAGNETS 0.4” x 1” minicylinders

31 Preliminary Results N48 mini-cylinders, 24 hour total soak time FEBRUARY 2006 – UNDERSIZED MAGNETS 0.4” x 1” minicylinders Polarized along length, weak flux

32 Preliminary Results N48 mini-cylinders, 24 hour total soak time FEBRUARY 2006 – UNDERSIZED MAGNETS ControlsTreatments Sharks captured 3 tigers (TL>2m) in same 4hr period

33 Preliminary Results N48 1” cylinders, 24 hour total soak time FEBRUARY 2006 CONTINUED 1”x1” N48 cylinders

34 Preliminary Results N48 1” cylinders, 24 hour total soak time FEBRUARY 2006 CONTINUED Sharpnose

35 Preliminary Results N50 1”x1” cylinder with 2” tophat N50 1” cylinders with tophats, 48 hour total soak time JUNE 2006

36 Preliminary Results N50 1” cylinders with tophats, 48 hour total soak time No sharks captured on treatments JUNE 2006

37 Next Steps  Many more tests  CPUE is too low November 2006 NOAA cruise Alaskan and Chilean fisheries

38 Acknowledgements Bimini Biological Field Station Dr. Samuel Gruber Steve Kessel, Tristan Guttridge, Grant Johnson, Katie Grudecki, Jo Imhoff, and the crew Vernon Scholey, IATTC NOAA – Pascagoula Mark A. Grace Charles Bergmann RSMAS Dr. Dan Benetti Patrick H. Rice WWF SmartGear 2006 Committee Kim Davis Rodrigo Donadi George Mizzell, ENG Concepts


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