Semiochemicals as Shark Repellents: Identification and Behavioral Response

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Semiochemicals as Shark Repellents
Identification and Behavioral Response

• Eric M. Stroud
• Michael M. Herrmann
• Dr. Samuel G. Gruber

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Semiochemical Mixture

• Semiochemicals are messengers or clues
• Shark-specificity
• Non-lethal
• Action is suspected to be olfactory (mouth dose
  is not required)
• Not based on Cu, surfactants, acid, or dye
• Safe to handle and store

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Discovery of the Mixture

• Shark carcass Not decayed, no Cu, no ammonium
  acetate
• Production
• Multi-phase extraction process
• Deproteinization
• Filtration
• Neutralization
• Modern analytical instrumentation
• Mixture of nucleotides

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Analytical Tools

• Visible / IR Spectrophotometry
• Fluorimetry
• Derivatization and HPLC
• Flash Chromatography and TLC
• GC-MS

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GC-MS Total Ion Chromatograph
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Field Tests

• Find a suitable wild shark population
• Construct a delivery apparatus
• Test a behavioral control
• Test a variety of fractions of the semiochemical
  mixture
• Quantify results

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Testing Locations

• BBFS South Bimini
• Blacknose, Caribbean Reef, Lemon, Bull sharks
• Ordinance Dump Montauk, NY
• Blue sharks

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Delivery Apparatus

• Based on Donald Nelsons design
• Pressurized delivery of liquid through a tube to
  a fish head suspended on a pole
• Pressures ranges from 5- 20 psig
• Delivery volumes ranges from 100mL to 500mL

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Controls and Repellents

• Control is introduced while sharks are actively
  feeding
• Seawater with or without FDC Red 3 40, at the
  same pressure and dose size for the repellent
• Repellent is introduced while sharks are actively
  feeding
• Observations are made on the size of the feeding
  population before and after dosing
• Observations are made on changes in feeding
  behavior

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Results

• Controls
• Feeding shark populations were not diminished for
  control deliveries of up to 20 psig
• Plain seawater nor FDC Red 3 40 and seawater
  did not deter feeding
• Sharks are not afraid to feed from and near the
  delivery apparatus

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Results

• Repellents
• 100mL to 250mL doses of the semiochemical mixture
  dramatically reduce the feeding population size
• Nearby fish are unaffected and continue feeding
• In six separate field tests, feeding populations
  of 2 to 12 Blacknose and Caribbean Reef sharks
  are reduced to 0 within 120 seconds of a
  subsurface dose
• Visual behavior changes occur within 20 seconds
  of the subsurface dose
• 4 fl oz is the optimal dose size for large
  populations, but response has been observed with
  as little as 25mL

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Species and Populations

• Blacknose / Caribbean Reef Sharks Up to 12
• Blue Sharks 2
• Bull Sharks 2
• Lemon Sharks 2
• Nurse Sharks - 2

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Cloud Test Population 12
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Tonic Immobility Test
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0.1ppm Criteria

• Test for a behavioral response at with 0.1 ppm of
  the chemical repellent
• Johnson-Baldridge proposed that a 100mL/hr
  release of a chemical repellent into a 6m3
  boundary of water under steady-state conditions
  for 3.5 hours represents 0.1 ppm.

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0.1ppm Criteria

• Use a tall plastic tripod with wireless camera to
  observe a 6m3 boundary of water, with a fish head
  suspended in the 6m3 boundary
• Chum to attract sharks into the boundary area,
  let them take the fish head
• Begin metered dosing of the repellent using a
  precision peristaltic pump into the boundary once
  a population is established, using a new fish
  head
• New fish head must remain protected for 3.5 hours

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Johnson-Baldridge Apparatus
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0.1ppm Results

• September 2003
• Fish head was protected for 1.5 hours from two
  lemon sharks, until medical pump battery died
• March 2004
• Fish head was protected for 2 hours from two
  Caribbean reef sharks, until pump failed
• May 2004
• Successfully performed and videod a control

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Next Steps

• More field testing
• Tiger, Great White, Hammerhead, Oceanic Whitetip
• More validation
• Bull, blue
• Perfect synthesis pathway for commercialization

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