As a result of a co-operative undertaking of the Laboratorio del Instituto de Investigaciones Pesqueras of Cadiz with the Marine Laboratory of the University of Miami, carried out by us during the years 1960 and 1961, twenty-one specimens of Istiophoridae were obtained, of which nineteen were Tetrapturus albidus. Two of the twenty-one specimens were not identified and are not dealt with here. Some of these fish were captured on lines operated by fishermen for the capture of the swordfish (Xiphias gladius L.) off the south Atlantic coast of Spain and Portugal, and in the Straits of Gibraltar. The balance of these fish were caught in the tuna-trap (Almadraba), ‘Nueva Umbria’, situated off the town of Isla Cristinal not far from Huelva, on the south Atlantic coast of Spain, and in the trap ‘La Atunara’, situated off the town of La Linea, in the Mediterranean Sea, just east of the Straits of Gibraltar. Table 1 shows the catches of the 19 specimens identified as T. albidus.