Strong magnets have been trialled as a means of deterring sharks from approaching baited hooks. Preliminary observations on captive pelagic stingrays (Poisson et al. 2019) when strong magnets mainly composed of neodymium (26mm×11mm×12mm 0.885 T from Ingeniera Magnetica Aplicada, Barcelona, Spain) were placed close to the food should little or no effect of magnetic repellents, and such systems would be unlikely to reduce catch rates.