By-catch in the mesopelagic swordfish longline fishery in the Ligurian Sea (western Mediterranean)

In 2010 the new mesopelagic long line was introduced in the Ligurian Sea swordfish fishery, substituting the traditional surface longline. The by-catch was greatly reduced, showing also remarkable changes in the species composition. Swordfish represent about 70% by numbers of the total commercial catches, which is mainly made up of a few species: bluefin tuna, Thunnus thynnus, albacore, T. alalunga, rudderfish, Centrolophus niger, pomfret, Brama.brama, dolphinfish, Coryphaena hippurus, opah,. Lampris guttatus, wreckfish, Polyprion americanus and among elasmobranchs, only blue shark, Prionace glauca and little sleeper shark, Somniosus rostratus. Discards species are sunfish, Mola mola, pelagic stingray, Pteroplatytrygon violacea, scalloped ribbonfish, Zu cristatus, ribbonfish, Trachipterus trachypterus, and the Paralepidid fish Sudis hyalina. The impact of this new gear on protected or endangered species, such as sea turtles and all other species of pelagic sharks resulted absolutely negligible.