title: Changes in body condition and fatty acid composition of wild Mediterranean horse mackerel (Trachurus mediterraneus, Steindachner, 1868) associated to sea cage fish farms.
abstract: Net-cage fish farms attract a great number of wild fishes, altering their behaviour and possibly their physiology. Wild Mediterranean horse mackerel (Trachurus mediterraneus), sampled from populations aggregated around two Mediterranean fish farms and from two natural control populations, were analyzed for differences in body condition, stomach content and fatty acid composition. Pellets used to feed caged fish in both farms were also analyzed to identify their relationship with the fatty acid composition of tissue of wild fish. T. mediterraneus aggregated around the farms throughout the year although large seasonal changes in abundance and biomass occurred. Wild fish aggregated at farms mainly ate food pellets while control fish fed principally on juvenile fish and cephalopods. Wild fish that fed around the cages had a significantly higher body fat content than the control fish (7.30+/-1.8% and 2.36+/-0.7%, respectively). The fatty acid composition also differed between farm-associated and control fish, principally because of the significantly increased levels of linoleic (C18:2omega6) and oleic (C18:1omega9) acids and decreased docosahexaenoic acid (C22:6omega3) in farm-associated fish. The increased condition of wild fish associated with farms could increase the spawning ability of coastal fish populations, if wild fish are protected from fishing while they are present at farms. The fatty acids compositions could also serve as biomarkers to infer the influence of a fish farm on the local fish community, helping to better describe the environmental impact of fish farming.
authors.affiliation: Marine Biology Unit, Department of Marine Sciences and Applied Biology, University of Alicante, PO Box 99, E - 03080, Alicante, Spain. jover@ua.es
authors.forename: Damian
authors.initials: D
authors.lastname: Fernandez-Jover
authors.forename: Jose Angel Lopez
authors.initials: JA
authors.lastname: Jimenez
authors.forename: Pablo
authors.initials: P
authors.lastname: Sanchez-Jerez
authors.forename: Just
authors.initials: J
authors.lastname: Bayle-Sempere
authors.forename: Francisca Gimenez
authors.initials: FG
authors.lastname: Casalduero
authors.forename: Francisco Javier Martinez
authors.initials: FJ
authors.lastname: Lopez
authors.forename: Tim
authors.initials: T
authors.lastname: Dempster
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D018533:Biomass; D001824:Body Constitution; D004032:Diet; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D005247:Feeding Behavior; D005398:Fisheries; D005766:Gastrointestinal Contents; D005843:Geography; D019083:Mediterranean Region; D010473:Perciformes / Q000033:anatomy & histology / Q000378:metabolism* / Q000502:physiology; D012621:Seasons
chemical_list: D005227:Fatty Acids