SharkGuard is an experimental product that uses electric fields to deter sharks and other elasmobranchs from fishing hooks, while not interfering with target species. See 'Magnetic, E+ metals and electrical deterrents'.
From the Fishtek marine website:
Following successful trials of prototype I, Fishtek Marine worked with French industry partners to secure funding from the EU (Eurostars) to develop and test a more advanced prototype device in an Atlantic bluefin tuna (Thunnus thynnus) fishery in the Mediterranean. Prototype II was driven by 2 x AA alkaline batteries and emitted an electrical pulse with programmable characteristics enabling the pulse train, duty cycle and electric field strength to be varied. A paired vessel trial was undertaken to compare elasmobranch bycatch rates on a SharkGuard treatment versus a control treatment (standard gear) in the Autumn of 2019.
The number of pelagic stingrays (Pteroplatytrygon violacea) caught per 1000 hooks was reduced by 66% between control and active SharkGuard hooks. Although the catch rate of sharks was low throughout the trials, no blue shark was caught on a SharkGuard hook through the trials. The catch rate of bluefin tuna for SharkGuard hooks was also reduced, however this is likely due to the weight of the SharkGuard units altering the fishing depth of the baited hooks. Originally the SharkGuard was designed to reduce the globally unsustainable catch rates of blue sharks (and other high risk species e.g. Silky shark (Carcharhinus falciformis) and Shortfin mako shark (Isurus oxyrinchus).
SharkGuard Prototype III is under development.