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Ask Eric Stroud Ask Eric Stroud eric@sharkdefense.com eric@sharkdefense.com (201) (201)

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Portions Patent Pending, SharkDefense LLCPortions Patent Pending, SharkDefense LLC

EFFECTS OF MAGNETIC EFFECTS OF MAGNETIC FIELDS EXCEEDING 50 FIELDS EXCEEDING 50 GAUSSGAUSS

Michael M. HerrmannMichael M. Herrmann

Eric M. StroudEric M. Stroud

Dr. Samuel GruberDr. Samuel Gruber

IntroductionIntroduction

High-strength fieldsHigh-strength fields Close range phenomenon Close range phenomenon Definite behavioral changesDefinite behavioral changes Electromagnet vs. Electromagnet vs.

PermanentPermanent BioassaysBioassays

•Kalmijn, Tricas, Klimley (2000)•Meyer, Holland, Papastamatiou (2004)

Permanent Magnetic Permanent Magnetic FieldsFields Fe, SmCo, AlnicoFe, SmCo, Alnico NdFeB grades N38–50NdFeB grades N38–50 Br ~ 14,000G (1.4T)Br ~ 14,000G (1.4T) Surface > 0.1TSurface > 0.1T F ~ 1/dF ~ 1/d33

F. W. Bell teslameterF. W. Bell teslameter Transverse Hall probeTransverse Hall probe Thyssen pole finderThyssen pole finder

Permanent Magnetic Permanent Magnetic FieldsFields

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 5 10 15 20 25 30

Measured

Predicted

INCHES

GAUSS

Tonic ImmobilityTonic Immobility

Immobilized sharkImmobilized shark Plastic rulerPlastic ruler 4” x 1.5” cylindrical 4” x 1.5” cylindrical

NdFeBNdFeB Note behavior vs. Note behavior vs.

distance to magnetdistance to magnet Vary orientation of Vary orientation of

magnet or subjectmagnet or subject Use a blinder to Use a blinder to

remove visual clueremove visual clue

Tonic Immobility Tonic Immobility ResponsesResponses

Bending away from magnet faceBending away from magnet face Termination of TITermination of TI

Tonic Immobility Tonic Immobility VariancesVariances

Sometimes, NO Sometimes, NO effect is seeneffect is seen

Cannot perform a Cannot perform a chemical repellent chemical repellent test followed by a test followed by a magnet testmagnet test

Cannot perform a Cannot perform a magnet test magnet test followed by a followed by a chemical testchemical test

Sometimes, Sometimes, bismuth metal bismuth metal terminates TIterminates TI

Magnet at d=0”

Tonic ImmobilityTonic Immobility

Ginglymostoma cirratumGinglymostoma cirratum, , Negaprion Negaprion brevirostrisbrevirostris

In 31 subjects, range 0.0m to 0.3m:In 31 subjects, range 0.0m to 0.3m: Terminated TI:Terminated TI:

– 2 lemons, 6 nurses with moving magnet2 lemons, 6 nurses with moving magnet– 6 nurses with moving subject6 nurses with moving subject

Bending:Bending:– 5 nurses5 nurses– 1 lemon1 lemon

No Effect:No Effect:– 4 lemons4 lemons– 4 nurses 4 nurses

Electromagnet Electromagnet ComparisonComparison WeakWeak

– Iron core Iron core electromagnet electromagnet

– 12VDC, 6.16 – 6.28A, 12VDC, 6.16 – 6.28A, 10-2000mG, 0.0m – 10-2000mG, 0.0m – 1.0m1.0m

StrongStrong– 965# pull Locknetics 965# pull Locknetics

electromagnet at electromagnet at close range did not close range did not terminate TI in x terminate TI in x teststests

– 12VDC, 20A, ~20 12VDC, 20A, ~20 gauss, 0.0m-0.3mgauss, 0.0m-0.3m

Y-MazeY-Maze

Clear 8” acrylic tubesClear 8” acrylic tubes One entrance, one exit, one trap, One entrance, one exit, one trap,

one wayone way Uncooked shrimp reward Uncooked shrimp reward 4”x1.5” cylindrical NeFeB is used 4”x1.5” cylindrical NeFeB is used

as negative reinforcementas negative reinforcement Assign a score based on Assign a score based on

movementsmovements

Y-MazeY-Maze

Y-MazeY-Maze

TRAP

ENTRANCE

EXIT

Y-MazeY-Maze

TRAP

ENTRANCE

EXIT

2 SHRIMP

2 SHRIMP

1 SHRIMP (TEASER)

Y-MazeY-Maze

Results:Results:– ALWAYS distress ALWAYS distress

when trap tube is when trap tube is selectedselected

– Food is not taken Food is not taken in trap tubein trap tube

– Nurse sharks Nurse sharks learn very quicklylearn very quickly

– Aversive response Aversive response starts at 18 starts at 18 inches, or ~10Ginches, or ~10G

TRAP

Free-Swimming TestFree-Swimming Test

Camouflage Camouflage magnet in sandmagnet in sand

Introduce magnet Introduce magnet to side of tank wallto side of tank wall

Observe behavior Observe behavior when shark enters when shark enters fieldfield

Free-Swimming Free-Swimming ResultsResults Rapid aversive response when Rapid aversive response when

within 12” of magnetwithin 12” of magnet N/S neutral to oncoming sharkN/S neutral to oncoming shark Surface areaSurface area

Next stepsNext steps

July 11-14 – Captive July 11-14 – Captive ThunnusThunnus More preference tests, currently training More preference tests, currently training

lemon sharkslemon sharks Field tests August on free swimming Field tests August on free swimming P. P.

glaucaglauca More field tests in 2005-2006 on free More field tests in 2005-2006 on free

swimming swimming C. limbatus, C. perezii, C. C. limbatus, C. perezii, C. leucasleucas

See us for results and data of our projectSee us for results and data of our project Blacktip bracelet?Blacktip bracelet?

Special Thanks To:Special Thanks To:

Patrick Rice, NOAAPatrick Rice, NOAA David JacobyDavid Jacoby Tristan GuttridgeTristan Guttridge Grant Johnson, BBFS Lab ManagerGrant Johnson, BBFS Lab Manager Bryan Franks, BBFS PIBryan Franks, BBFS PI Katie Grudecki, BBFS Lab Katie Grudecki, BBFS Lab

ManagerManager