Tuna farming. Gulls mobbing a boat carrying defrosted mackerel (family Scombridae) and sardines (family Clupeidae) being carried to 'fattening pens' holding captured Atlantic bluefin tuna (Thunnus thynnus). 15 tonnes of these fish are fed to 1500 captive tuna per day in order to fatten them up for the Japanese market. Photographed in Andalucia, Spain.