Measurement of electromagnetic fields produced by underwater equipment

The elasmobranchii (sharks, rays and skates) possess sensory organs called the Ampullae of Lorentzini which enables them to detect electromagnetic (EM) fields at intensities as low as 1 μV/m at frequencies between 0.1 and 16 Hz. This paper describes the laboratory based measurement system used to measure the EM fields produced by commercial and recreational electronic scuba diving equipment. Using these measurements and software modelling, predictions can be made concerning the distance at which the elasmobranchii would be able to sense the presence of such equipment or the intensity of the fields at any given distance from the source.