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CONFIDENTIAL Please do not distribute – Ask Eric Stroud eric@sharkdefense.com (201) 240-0826 Portions Patent Pending,

CONFIDENTIAL Please do not distribute – Ask Eric Stroud eric@sharkdefense.com (201) 240-0826 Portions Patent Pending, SharkDefense LLC. EFFECTS OF MAGNETIC FIELDS EXCEEDING 50 GAUSS. Michael M. Herrmann Eric M. Stroud Dr. Samuel Gruber. Introduction. High-strength fields

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CONFIDENTIAL Please do not distribute – Ask Eric Stroud eric@sharkdefense.com (201) 240-0826 Portions Patent Pending,

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  1. CONFIDENTIAL Please do not distribute – Ask Eric Stroud eric@sharkdefense.com (201) 240-0826 Portions Patent Pending, SharkDefense LLC

  2. EFFECTS OF MAGNETIC FIELDS EXCEEDING 50 GAUSS Michael M. Herrmann Eric M. Stroud Dr. Samuel Gruber

  3. Introduction • High-strength fields • Close range phenomenon • Definite behavioral changes • Electromagnet vs. Permanent • Bioassays • Kalmijn, Tricas, Klimley (2000) • Meyer, Holland, Papastamatiou (2004)

  4. Permanent Magnetic Fields • Fe, SmCo, Alnico • NdFeB grades N38–50 • Br ~ 14,000G (1.4T) • Surface > 0.1T • F ~ 1/d3 • F. W. Bell teslameter • Transverse Hall probe • Thyssen pole finder

  5. Permanent Magnetic Fields GAUSS INCHES

  6. Tonic Immobility • Immobilized shark • Plastic ruler • 4” x 1.5” cylindrical NdFeB • Note behavior vs. distance to magnet • Vary orientation of magnet or subject • Use a blinder to remove visual clue

  7. Tonic Immobility Responses • Bending away from magnet face • Termination of TI

  8. Tonic Immobility Variances • Sometimes, NO effect is seen • Cannot perform a chemical repellent test followed by a magnet test • Cannot perform a magnet test followed by a chemical test • Sometimes, bismuth metal terminates TI Magnet at d=0”

  9. Tonic Immobility • Ginglymostoma cirratum, Negaprion brevirostris • In 31 subjects, range 0.0m to 0.3m: • Terminated TI: • 2 lemons, 6 nurses with moving magnet • 6 nurses with moving subject • Bending: • 5 nurses • 1 lemon • No Effect: • 4 lemons • 4 nurses

  10. Electromagnet Comparison • Weak • Iron core electromagnet • 12VDC, 6.16 – 6.28A, 10-2000mG, 0.0m – 1.0m • Strong • 965# pull Locknetics electromagnet at close range did not terminate TI in x tests • 12VDC, 20A, ~20 gauss, 0.0m-0.3m

  11. Y-Maze • Clear 8” acrylic tubes • One entrance, one exit, one trap, one way • Uncooked shrimp reward • 4”x1.5” cylindrical NeFeB is used as negative reinforcement • Assign a score based on movements

  12. Y-Maze

  13. Y-Maze TRAP EXIT ENTRANCE

  14. Y-Maze TRAP EXIT 2 SHRIMP 2 SHRIMP ENTRANCE 1 SHRIMP (TEASER)

  15. Y-Maze • Results: • ALWAYS distress when trap tube is selected • Food is not taken in trap tube • Nurse sharks learn very quickly • Aversive response starts at 18 inches, or ~10G TRAP

  16. Free-Swimming Test • Camouflage magnet in sand • Introduce magnet to side of tank wall • Observe behavior when shark enters field

  17. Free-Swimming Results • Rapid aversive response when within 12” of magnet • N/S neutral to oncoming shark • Surface area

  18. Next steps • July 11-14 – Captive Thunnus • More preference tests, currently training lemon sharks • Field tests August on free swimming P. glauca • More field tests in 2005-2006 on free swimming C. limbatus, C. perezii, C. leucas • See us for results and data of our project • Blacktip bracelet?

  19. Special Thanks To: • Patrick Rice, NOAA • David Jacoby • Tristan Guttridge • Grant Johnson, BBFS Lab Manager • Bryan Franks, BBFS PI • Katie Grudecki, BBFS Lab Manager

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