For centuries man has used lights to attract and concentrate fishes near the sea surface to aid their capture by nets or hooks (Ben-Yami, 1982). Underwater lights lowered into shallow seas are now regularly used to lure fish into set nets, large nets suspended beneath ships or into the vicinity of powerful pumps (Sidelnicov, 1981; Andreev, 1962; Nikonorov, 1969). Usually lights of more than 1 kw are used and such power requires a surface generator and strong insulated cable from the surface to the light. Although we know from these applications that some fish species are attracted by lights, the use of lights on trawls has not been developed for commercial exploitation or for research sampling. Perhaps such development has been discouraged by the safety problem and technical difficulties of providing electrical power on deck and handling heavily insulated conducting cable between the trawl and the generator. Lights have been used on commercial trawls with television in experiments to study fish reaction to trawls but such experiments were not concerned with finding the effect that lights might have on the quantity of fish caught and catches have not been analysed (A. Maclntyre, personal communication).