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Electropositive shark repellent

January 01, 1970

Electropositive metals (EPMs) are a new class of shark repellent materials that produce a measurable voltage when immersed in an electrolyte such as seawater. The voltages produced are as high as 1.75 VDC in seawater. It is hypothesized that this voltage overwhelms the ampullary organ in sharks, producing a repellent action. Since bony fish lack the ampullary organ, the repellent is selective to sharks and rays. The process is electrochemical, so no external power input is required. As chemical work is done, the metal is lost in the form of corrosion. Depending on the alloy or metal utilized and its thickness, the electropositive repellent effect lasts up to 48 hours. The reaction of the electropositive metal in seawater produces hydrogen gas bubbles and an insoluble nontoxic hydroxide as a precipitate which settles downward in the water column.

History edit

SharkDefense made the discovery of electrochemical shark repellent effects on May 1, 2006 at South Bimini, Bahamas at the Bimini Biological Field Station. An electropositive metal, which was a component of a permanent magnet, was chosen as an experimental control for a tonic immobility experiment by Eric Stroud using a juvenile lemon shark (Negaprion brevirostris). It was anticipated that this metal would produce no effect, since it was not ferromagnetic. However, a violent rousing response was observed when the metal was brought within 50 cm of the shark's nose. The experiment was repeated with three other juvenile lemon sharks and two other juvenile nurse sharks (Ginglymostoma cirratum), and care was taken to eliminate all stray metal objects in the testing site. Patrick Rice, Michael Herrmann, and Eric Stroud were present at this first trial. Mike Rowe, from Discovery Channel’s Dirty Jobs series, subsequently witnessed and participated in a test using an electropositive metal within 24 hours after the discovery.[1]

In the next three months, a variety of transition metals, lanthanides, post-transition metals, metalloids, and non-metal samples were screened for rousing activity using the tonic immobility bioassay in juvenile lemon sharks and juvenile nurse sharks. All behaviors were scored from 0 to 4 depending on the response. It was determined that Group I, II, III, and Lanthanide metals all produced rousing responses, but the average score generally increased with electropositivity.[2]

Further testing using salt bridge electrochemical cells were conducted during 2006 and 2007 at the Oak Ridge Shark Lab. Using seawater as the electrolyte and a shark fin clipping as the cathode, voltages measured closely correlated with the standard reduction potential of the metal under test. SharkDefense now hypothesizes that a net positive charge from the cations produced by the electropositive metals accumulate on the electronegative skin of the shark. The net increase of the charge on the shark's skin is perceived by the ampullae of Lorenzini, and above 1.2 eV potential, aversion is produced.

Electropositive metals are reducing agents and liberate hydrogen gas in seawater via hydrolysis, producing a half-cell voltage of about −0.86 eV. Simultaneously, an insoluble metal hydroxide precipitate is produced, which is inert for shark repellent activity. As such, metal is lost to corrosion in the process of generating cations. SharkDefense conducted corrosion loss studies in 2008 at South Bimini, Bahamas, and found that a 70 gram piece of a custom electropositive alloy retained more than 50% of its original weight after 70 hours of immersion. Losses due to corrosion are heavily a function of temperature, therefore, the cold seawater at fishing depths serves to reduce the corrosion rate.[3]

Research and testing edit

Stoner and Kaimmer (2008)[4] reported success using cerium mischmetal and Pacific spiny dogfish (Squalus acanthias, a type of shark) in captivity, both with tonic immobility and feeding preference tests. Lead metal was used as a control. Encouraged by the results, a longline study was conducted off Homer, Alaska in late 2007 with the cooperation of the International Pacific Halibut Commission. Again, lead was used as a control. This study found a 17% reduction in Pacific spiny dogfish catch, and a 48% reduction in clearnose skate catch.

However, Tallack et al. reported that cerium mischmetal was entirely ineffective[5] against Atlantic spiny dogfish in the Gulf of Maine. Mandelman et al. reported that the repellent effect disappeared after starvation using captive Atlantic spiny dogfish, and that a species-specific variation in response to the mischmetals exist between captive Atlantic spiny dogfish and dusky smoothhounds (Mustelis canis).[6]

Stroud (SharkDefense, 2006) and Fisher (VIMS) observed captive cownose rays (Rhinoptera bonasus) changing swim elevation and ignoring blue crab baits in cages that contained neodymium-praseodymium mischmetal. The position of the treatment cages were alternated, and all cages were placed in the swim path of the rays.

Brill et al. (2008) reported that captive juvenile sandbar sharks (Carcharhinus plumbeus) maintained a 50–60 cm clearance in their swimming patterns when a piece of neodymium-praseodymium mischmetal was placed in the tank.

Wang, Swimmer, and Laughton (2007) reported aversive responses to neodymium-praseodymium mischmetals placed near baits offered to adult Galapagos (C. galapagensis) and Sandbar sharks on bamboo poles in Hawaii. In July 2008 Richard Brill of NMFS/VIMS and SharkDefense both conducted more at-sea trials with electropositive metals in an effort to reduce shark bycatch in commercial fisheries. As of August 2, 2008, Brill reported nearly a 3:1 reduction in sandbar shark catch when plastic decoys were compared to metals. A high statistical significance was obtained, as reported in the Virginian-Pilot by Joanne Kimberlin. SharkDefense later developed a simple on-hook treatment and a bait attachment which were being tested on Atlantic longlining vessels in 2008.

Favaro and Cole (2013) determined through meta-analysis that electropositive metals did not reduce elasmobranch by-catch in commercial long-line fisheries,[7] which raises concerns on the effectiveness of this approach as a shark deterrent or repellent to protect water users.[8]

Selectivity edit

As expected, teleosts (bony fish) are not repelled by the electropositive metal's cation liberation in seawater. This is because teleosts lack the ampullae of Lorenzini. Teleost response was confirmed using captive Cobia (Rachycentron canadum) and Pacific halibut (Hippoglossus stenolepis). In July 2008 swordfish (Xiphias gladius) catch was reported on experimental hooks treated with electropositive metal.

Limitations edit

As with all shark repellents, 100% effectiveness will not be achieved with electropositive metals. The metals are particularly effective when the shark is relying on its electrosense. It is likely that electropositive metals are ineffective for deliberately stimulated (chummed) sharks, competitively feeding sharks, and shark "frenzies"[citation needed]. The metals are very useful in the environment of commercial fisheries, and possibly recreational and artisanal fisheries.

References edit

  1. ^ Video of test with electropositive metal
  2. ^ AES 2007 Abstract: The Use of Highly Electropositive Metals as Shark Repellents. Eric Stroud, Patrick Rice, Craig O'Connell, Samuel Gruber
  3. ^ AES 2008 Abstract: Advances in Shark Repellent Research Using Highly Electropositive Metals. Eric Stroud, Patrick Rice, Craig O'Connell, Samuel Gruber
  4. ^ "Reducing elasmobranch bycatch: Laboratory investigation of rare earth metal and magnetic deterrents with spiny dogfish and Pacific halibut". Stoner, Allan W. and Kaimmer, Stephen M. Fisheries Research, 2008.
  5. ^ Tallack, M.S.L & J. Mandelman, (in prep). Do rare earth metals deter spiny dogfish? A feasibility study on the use of Mischmetals to reduce dogfish catches in hook and lobster gear in Gulf of Maine.
  6. ^ AES 2008 Abstract: The Shifting Baseline of Threshold Feeding Responses to Electropositive Metal Deterrents in Two Species of Dogfish. John Mandelman, Michael Stratton, Michael Tlusty, Shelly Tallack, Tom Fisher, Cheryl Harary, Nils Wernerfelt
  7. ^ Favaro, Brett (1 September 2013). "Do by-catch reduction devices in longline fisheries reduce capture of sharks and rays? A global meta-analysis". Fish and Fisheries. 16: 306. Retrieved 23 July 2020.
  8. ^ Cardno (October 2015). "Shark Deterrents and Detectors Detectors Review of Bather Protection Review of Bather Protection Technologies Technologies" (PDF). Retrieved 23 July 2020. {{cite journal}}: Cite journal requires |journal= (help)

Further reading edit

  • Prindle, Drew Prindle (August 20, 2014). "Nope, that's not a house arrest anklet — it's the world's first acoustic shark repeller". Digital Trends.

January 01, 1970
electropositive, shark, repellent, electropositive, metals, epms, class, shark, repellent, materials, that, produce, measurable, voltage, when, immersed, electrolyte, such, seawater, voltages, produced, high, seawater, hypothesized, that, this, voltage, overwh. Electropositive metals EPMs are a new class of shark repellent materials that produce a measurable voltage when immersed in an electrolyte such as seawater The voltages produced are as high as 1 75 VDC in seawater It is hypothesized that this voltage overwhelms the ampullary organ in sharks producing a repellent action Since bony fish lack the ampullary organ the repellent is selective to sharks and rays The process is electrochemical so no external power input is required As chemical work is done the metal is lost in the form of corrosion Depending on the alloy or metal utilized and its thickness the electropositive repellent effect lasts up to 48 hours The reaction of the electropositive metal in seawater produces hydrogen gas bubbles and an insoluble nontoxic hydroxide as a precipitate which settles downward in the water column Contents 1 History 2 Research and testing 3 Selectivity 4 Limitations 5 References 6 Further readingHistory editSharkDefense made the discovery of electrochemical shark repellent effects on May 1 2006 at South Bimini Bahamas at the Bimini Biological Field Station An electropositive metal which was a component of a permanent magnet was chosen as an experimental control for a tonic immobility experiment by Eric Stroud using a juvenile lemon shark Negaprion brevirostris It was anticipated that this metal would produce no effect since it was not ferromagnetic However a violent rousing response was observed when the metal was brought within 50 cm of the shark s nose The experiment was repeated with three other juvenile lemon sharks and two other juvenile nurse sharks Ginglymostoma cirratum and care was taken to eliminate all stray metal objects in the testing site Patrick Rice Michael Herrmann and Eric Stroud were present at this first trial Mike Rowe from Discovery Channel s Dirty Jobs series subsequently witnessed and participated in a test using an electropositive metal within 24 hours after the discovery 1 In the next three months a variety of transition metals lanthanides post transition metals metalloids and non metal samples were screened for rousing activity using the tonic immobility bioassay in juvenile lemon sharks and juvenile nurse sharks All behaviors were scored from 0 to 4 depending on the response It was determined that Group I II III and Lanthanide metals all produced rousing responses but the average score generally increased with electropositivity 2 Further testing using salt bridge electrochemical cells were conducted during 2006 and 2007 at the Oak Ridge Shark Lab Using seawater as the electrolyte and a shark fin clipping as the cathode voltages measured closely correlated with the standard reduction potential of the metal under test SharkDefense now hypothesizes that a net positive charge from the cations produced by the electropositive metals accumulate on the electronegative skin of the shark The net increase of the charge on the shark s skin is perceived by the ampullae of Lorenzini and above 1 2 eV potential aversion is produced Electropositive metals are reducing agents and liberate hydrogen gas in seawater via hydrolysis producing a half cell voltage of about 0 86 eV Simultaneously an insoluble metal hydroxide precipitate is produced which is inert for shark repellent activity As such metal is lost to corrosion in the process of generating cations SharkDefense conducted corrosion loss studies in 2008 at South Bimini Bahamas and found that a 70 gram piece of a custom electropositive alloy retained more than 50 of its original weight after 70 hours of immersion Losses due to corrosion are heavily a function of temperature therefore the cold seawater at fishing depths serves to reduce the corrosion rate 3 Research and testing editStoner and Kaimmer 2008 4 reported success using cerium mischmetal and Pacific spiny dogfish Squalus acanthias a type of shark in captivity both with tonic immobility and feeding preference tests Lead metal was used as a control Encouraged by the results a longline study was conducted off Homer Alaska in late 2007 with the cooperation of the International Pacific Halibut Commission Again lead was used as a control This study found a 17 reduction in Pacific spiny dogfish catch and a 48 reduction in clearnose skate catch However Tallack et al reported that cerium mischmetal was entirely ineffective 5 against Atlantic spiny dogfish in the Gulf of Maine Mandelman et al reported that the repellent effect disappeared after starvation using captive Atlantic spiny dogfish and that a species specific variation in response to the mischmetals exist between captive Atlantic spiny dogfish and dusky smoothhounds Mustelis canis 6 Stroud SharkDefense 2006 and Fisher VIMS observed captive cownose rays Rhinoptera bonasus changing swim elevation and ignoring blue crab baits in cages that contained neodymium praseodymium mischmetal The position of the treatment cages were alternated and all cages were placed in the swim path of the rays Brill et al 2008 reported that captive juvenile sandbar sharks Carcharhinus plumbeus maintained a 50 60 cm clearance in their swimming patterns when a piece of neodymium praseodymium mischmetal was placed in the tank Wang Swimmer and Laughton 2007 reported aversive responses to neodymium praseodymium mischmetals placed near baits offered to adult Galapagos C galapagensis and Sandbar sharks on bamboo poles in Hawaii In July 2008 Richard Brill of NMFS VIMS and SharkDefense both conducted more at sea trials with electropositive metals in an effort to reduce shark bycatch in commercial fisheries As of August 2 2008 Brill reported nearly a 3 1 reduction in sandbar shark catch when plastic decoys were compared to metals A high statistical significance was obtained as reported in the Virginian Pilot by Joanne Kimberlin SharkDefense later developed a simple on hook treatment and a bait attachment which were being tested on Atlantic longlining vessels in 2008 Favaro and Cole 2013 determined through meta analysis that electropositive metals did not reduce elasmobranch by catch in commercial long line fisheries 7 which raises concerns on the effectiveness of this approach as a shark deterrent or repellent to protect water users 8 Selectivity editAs expected teleosts bony fish are not repelled by the electropositive metal s cation liberation in seawater This is because teleosts lack the ampullae of Lorenzini Teleost response was confirmed using captive Cobia Rachycentron canadum and Pacific halibut Hippoglossus stenolepis In July 2008 swordfish Xiphias gladius catch was reported on experimental hooks treated with electropositive metal Limitations editAs with all shark repellents 100 effectiveness will not be achieved with electropositive metals The metals are particularly effective when the shark is relying on its electrosense It is likely that electropositive metals are ineffective for deliberately stimulated chummed sharks competitively feeding sharks and shark frenzies citation needed The metals are very useful in the environment of commercial fisheries and possibly recreational and artisanal fisheries References edit Video of test with electropositive metal AES 2007 Abstract The Use of Highly Electropositive Metals as Shark Repellents Eric Stroud Patrick Rice Craig O Connell Samuel Gruber AES 2008 Abstract Advances in Shark Repellent Research Using Highly Electropositive Metals Eric Stroud Patrick Rice Craig O Connell Samuel Gruber Reducing elasmobranch bycatch Laboratory investigation of rare earth metal and magnetic deterrents with spiny dogfish and Pacific halibut Stoner Allan W and Kaimmer Stephen M Fisheries Research 2008 Tallack M S L amp J Mandelman in prep Do rare earth metals deter spiny dogfish A feasibility study on the use of Mischmetals to reduce dogfish catches in hook and lobster gear in Gulf of Maine AES 2008 Abstract The Shifting Baseline of Threshold Feeding Responses to Electropositive Metal Deterrents in Two Species of Dogfish John Mandelman Michael Stratton Michael Tlusty Shelly Tallack Tom Fisher Cheryl Harary Nils Wernerfelt Favaro Brett 1 September 2013 Do by catch reduction devices in longline fisheries reduce capture of sharks and rays A global meta analysis Fish and Fisheries 16 306 Retrieved 23 July 2020 Cardno October 2015 Shark Deterrents and Detectors Detectors Review of Bather Protection Review of Bather Protection Technologies Technologies PDF Retrieved 23 July 2020 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Further reading editPrindle Drew Prindle August 20 2014 Nope that s not a house arrest anklet it s the world s first acoustic shark repeller Digital Trends Retrieved from https en wikipedia org w index php title Electropositive shark repellent amp oldid 1099171851, wikipedia, wiki, book, books, library,

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