Do elasmobranch reactions to magnetic fields in water show promise for bycatch mitigation?

Rigg, Damian P., Peverell, Stirling C., Hearndon, Mark, and Seymour, Jamie E. (2009) Do elasmobranch reactions to magnetic fields in water show promise for bycatch mitigation? Marine and Freshwater Research, 60 (9). pp. 942-948.

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Elasmobranchs are under increasing pressure from targeted fisheries worldwide, but unregulated bycatch is perhaps their greatest threat. This study tested five elasmobranch bycatch species (Sphyrna lewini, Carcharhinus tilstoni, Carcharhinus amblyrhynchos, Rhizoprionodon acutus, Glyphis glyphis) and one targeted teleost species (Lates calcarifer) to determine whether magnetic fields caused a reaction response and/or change in spatial use of experimental arena. All elasmobranch species reacted to magnets at distances between 0.26 and 0.58 m at magnetic strengths between 25 and 234 gauss and avoided the area around the magnets. Contrastingly, the teleosts showed no reaction response and congregated around the magnets. The different reactions of the teleosts and elasmobranchs are presumably driven by the presence of ampullae of Lorenzini in the elasmobranchs; different reaction distances between elasmobranch species appeared to correlate with their feeding ecology. Elasmobranchs with a higher reliance on the electroreceptive sense to locate prey reacted to the magnets at the greatest distance, except G. glyphis. Notably, this is the only elasmobranch species tested with a fresh- and salt-water phase in their ecology, which may account for the decreased magnetic sensitivity. The application of magnets worldwide to mitigate the bycatch of elasmobranchs appears promising based on these results.

Item ID: 10572
Item Type: Article (Research - C1)
ISSN: 1448-6059
Keywords: ferrite magnet, gill-net, tropical biology
Date Deposited: 08 May 2010 01:23
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060299 Ecology not elsewhere classified @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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