Turkish pelagic gillnet fishery for swordfish and incidental catches in the Aegean Sea

Abstract This study was carried out with 20 representative gill-netters based at the port of Sivrice and Sığacık from June 2008 to August 2010. The average length, gross tonnage (GT), machine power (hp) and number of personnel of the gill-netters were 10.4±0.6 m, 10.5±2.3 GT, 121.4±19.9 hp and 3.4±0.2 persons, respectively. Total length of all observed gillnets was reaching 339 km, ranged from 700 to 6000 m with average 2672 ±93 m. The mean CPUEs for swordfish by number and weight were calculated as 1.0 ±0.1 and 37.7 ±4.2 kg per km net, respectively. A total of 12 species, belongs to nine families were caught. The target species, swordfish had the highest ratio both in number (39.2%) and weight (73.1%) followed by Auxis rochei > Euthynnus alletteratus > Thunnus thynnus > Thunnus alalunga by number; Thunnus thynnus > Mola mola > Euthynnus alletteratus > Mobula mobular by weight. Biomass and number ratios of the non-target species to the target swordfish were 1:0.37 and 1:1.55, respectively. Four species, Caretta caretta, Dasyatis violacea, Mobula mobular, Mola mola were thrown back to the sea and the others were retained due to commercial value.