Oak Ridge, NJ, United States
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O'Connell C.P.,Coastal Carolina University | Abel D.C.,Coastal Carolina University | Rice P.H.,Florida College | Stroud E.M.,SharkDefense | Simuro N.C.,Clarkson College
Marine and Freshwater Behaviour and Physiology | Year: 2010

The behavioral responses of free-swimming, wild southern stingrays (Dasyatis americana) and nurse sharks (Ginglymostoma cirratum) to permanent magnets were evaluated in the Florida Keys, USA. Animals were attracted to a baited magnetic treatment board consisting of two 15 cm × 10 cm × 5 cm grade C8 Barium-Ferrite (empirically, BaFe12O19) permanent magnets producing a flux of 950 gauss at their surface and a baited procedural control board containing two smooth nonmagnetized clay bricks. In the presence of permanent magnets, D. americana and G. cirratum demonstrated a significantly greater number of avoidance behaviors away from the magnet side of the apparatus, while both species fed a significantly greater number of times from the non-magnetized procedural control side. Thus, D. americana and G. cirratum showed sensitivity to a magnetic field and were successfully repelled from baited areas containing magnets. The results from the current study suggest that the use of grade C8 Barium-Ferrite permanent magnets as an avoidance mechanism (e.g., repellent) to reduce elasmobranch mortalities associated with fishing operations and beach nets merits further investigation. © 2010 Taylor & Francis.


O'Connell C.P.,University of Massachusetts Dartmouth | O'Connell C.P.,Coastal Carolina University | O'Connell C.P.,SharkDefense | Abel D.C.,Coastal Carolina University | And 3 more authors.
Fishery Bulletin | Year: 2011

Previous studies indicate that elasmobranch fishes (sharks, skates and rays) detect the Earth's geomagnetic field by indirect magnetoreception through electromagnetic induction, using their ampullae of Lorenzini. Applying this concept, we evaluated the capture of elasmobranches in the presence of permanent magnets in hook-and-line and inshore longline fishing experiments. Hooks with neodymium-iron-boron magnets significantly reduced the capture of elasmobranchs overall in comparison with control and procedural control hooks in the hook-and-line experiment. Catches of Atlantic sharpnose shark (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were signif icantly reduced with magnetic hook-and-line treatments, whereas catches of spiny dogfish (Squalus acanthias) and clearnose skate (Raja eglanteria) were not. Longline hooks with barium-ferrite magnets significantly reduced total elasmobranch capture when compared with control hooks. In the longline study, capture of blacktip sharks (Carcharhinus limbatus) and southern stingrays (Dasyatis americana) was reduced on magnetic hooks, whereas capture of sandbar shark (Carcharhinus plumbeus) was not affected. Teleosts, such as red drum (Sciaenops ocellatus), Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata), and the bluefish (Pomatomas saltatrix), showed no hook preference in either hook-andline or longline studies. These resultsindicate that permanent magnets, although eliciting species-specific capture trends, warrant further investigation in commercial longline and recreational fisheries, where bycatch mortality is a leading contributor to declines in elasmobranch populations.


Stroud E.M.,SharkDefense | O'Connell C.P.,SharkDefense | Rice P.H.,SharkDefense | Snow N.H.,Seton Hall University | And 3 more authors.
Ocean and Coastal Management | Year: 2014

Since 1942, the search for an effective chemical shark repellent has been ongoing research concern in the United States. A long-standing anecdote that sharks avoid areas containing decomposing shark tissue has initiated new interest in identifying trace chemical alarm signals produced during decomposition (necromones). A commercially-sourced shark necromone produced from putrefied shark tissue was evaluated over a five-year period in South Bimini, Bahamas. Competitively-feeding populations of Caribbean reef sharks (Carcharhinus perezi) and blacknose sharks (Carcharhinus acronotus) were exposed to necromones using pressurized aerosol canisters at the surface. Shark density estimations were made at the initial, 1min and 5min intervals after preliminary exposure along with continuous exposure of feeding stimulus. In both species, an unambiguous halt in feeding behavior was observed within 1min after exposure of the necromone. For aerosol delivery, a 150mL dose of the necromone from a single aerosol canister is able to halt all feeding activity in a combined population of C.perezi and C.acronotus. Shark necromones induced a spectacular alarm response in interacting sharks resulting in a temporary evacuation of an area containing feeding stimuli. Additionally, sharks were not deterred by alternative treatment presentations of 10% weight percent (w/w) aqueous urea, 10% w/w oleic acid in ethanol, or water buffered to pH 8.5. Habituation to the necromone was not observed for repeated tests at the same location. In all experiments, the presence of a shark necromone did not produce a similar aversion response for teleosts as observed in C.perezi or C.acronotus; however, anecdotal observations demonstrate that teleosts increased their feeding rate in the presence of the necromone. Experimental controls using denatured ethanol or water confirmed that feeding sharks were not deterred by bubbles, sound, or the solvents used to extract the necromones. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry indicates that the necromone is a complex solution rich in amino acids and putrefaction products. Experiments demonstrate that the key chemical component responsible for the alarm response is within these amino acids and/or putrefaction products, but further experimentation is needed to more accurately identify the active ingredient. Shark necromones hold particular promise for use in shark bycatch reduction and conservation. The existence of a putative chemical shark repellent has been confirmed. © 2013 Elsevier Ltd.


Grant
Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 166.81K | Year: 2010

This Small Business Innovation Research (SBIR) Phase 1 project addresses unintended shark catch in commercial fisheries by creating an advanced fishing hook material that is repellent to sharks and not repellent to market-valuable fish. In the commercial longline fishing industry, it is not uncommon to capture more sharks than target fish. Unintended shark catch, or "bycatch", results because a baited hook is equally attractive to both fish and sharks. If unwanted sharks can be selectively repelled, the target fish catch can be maximized, allowing the industry to remain sustainable, profitable, and eligible for incentives from fishery regulators. To address this selective fishing requirement, the proposed technology combines two known shark repellent technologies directly into a fishing hook: Magnetism and electropositivity. These repellents affect the shark's unique electrical sense and are not detectable by tuna and swordfish, which lack the electrical sense. The proposed technology is transparent to fishermen because it will not require external power and will not change the shape, function, or handling of a standard hook. The broader/commercial impacts of this research are the training of new scientists and increased understanding of shark behavior and shark repellent materials. By identifying compounds with selective shark repellent activity, marine biologists will have an enhanced understanding of the behavioral differences between sharks and fishes. Technological understanding will be advanced identifying surface treatment techniques for metals used in marine environments. These techniques will provide direction for future shark-repellent coatings for marine aquaculture and marine infrastructure.


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Phone: (877) 571-2207 Address: PO Box 2593 Oak Ridge, NJ 07438 USADr. Patrick H ...


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Several species of sharks have demonstrated the ability to sense magnetic fieldsThe ampullae of Lorenzini are small vesicles and pores that form part of a subcutaneous sensory network of sharks. These vesicles and pores are found around the head of the shark and are visible to the naked eye ...


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This page is Copyright (c) SharkDefense Technologies, LLC 2013.General IntroductionSince antiquity, human encounters with sharks have been depicted as unfavorable ...


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Of Crocodiles and SharksJune 21, 2016 by Eric Stroud Leave a CommentSometimes, everything old is new again. We just wanted to reminisce on research conducted by the late esteemed L ...

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