Fully Documented Fisheries project, founded by the European Maritime and Fisheries Fund, aims, within the context of the forthcoming the European Landing Obligation, to fully document the catches from fisheries using Electronic Monitoring as a catch registration tool to automatically record the number and weight by species of the discarded catch. The detection of unwanted fish on board commercial bottom trawlers produces a logbook recording the total catch, weight, and length for each species. The presence of debris, catch occlusions on the sorting belt, fish overlapping, and the illuminance variation are the most fundamental challenges the system has to face.