Predator deterrent system 1, particularly for deterring predators of aquatic creatures such as fish 44 in submerged fish farms comprising at least one trigger device 28 configured to detect a predator 46 in the vicinity of a fish enclosure 10 and configured to generate an alarm signal responsive to the detection of the predator and at least one alarm device responsive to the alarm signal generated by the trigger device, the alarm device comprising at least one electrified enclosure section 40A-40H wherein upon receipt of an alarm signal generated by the trigger device at least one electrified enclosure section is powered. Control means 132 may be provided and the trigger devices may be motion detectors or sonar detectors. The enclosure may be an electrified net. A further predator deterrent system for a submerged first enclosure comprising a control means for controlling delivery of power to the at least one electrified enclosure section, a method of deterring predators, a method of manufacturing a predator deterrent system and a modular kit for a predator deterrent system are also described.
