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Gilthead sea bream and European sea bass aquaculture is widely established in the Mediterranean and North-eastern Atlantic regions, and rearing is mainly in coastal net-pen facilities. The rapid growth of the fish farming industry increases the potential number of farmed fish in the wild. Escape-related issues are likely to increase unless escape-management policies are included into the aquaculture legislation in the near future. This review summarizes the potential direct interactions among escaped fish and nearby farmed fish stocks, wild conspecifics, and coastal fish populations, since these interactions could compromise sustainability in coastal areas. Socioeconomic implications are also addressed, given that escape events can also lead to economic losses for farmers and may alter local fishery landings. Fish markets and consumers might be also affected. This review compiles the current knowledge on the potential effects of escapees in coastal areas, and contributes to the existing risks analyses regarding sea bream and sea bass escapes. Eventually, the need to design management policies to prevent or minimize escape events and to mitigate further impacts, applicable to Mediterranean countries and of special interest in areas where these species are locally absent, is discussed in the context of sustainable fin-fish aquaculture. [ABSTRACT FROM AUTHOR]

To examine site fidelity and potential for ecosystem impacts, 20 escapee cod ( Gadus morhua L.) from fjord-based cod farms were tagged with acoustic transmitters, released in the vicinity of the same farm, and their subsequent behaviour and survival monitored using a fixed array of acoustic receivers. Most individuals demonstrated high fidelity to their farm where tagged, and this increased during the polar night. Only five individuals (25%) were occasionally detected at another farm (4 km distance), and only three cod (15%) migrated out of the fjord during the 6-month study period. Vertical movements were consistently greater in the hours around noon than at night, a behaviour inconsistent with that observed for wild fish. A high mortality rate (40%) was observed during the first 4 months post-release, and actual mortality may have been even higher, limiting the potential for negative ecosystem effects from cod escapees. Findings from this study are used to discuss the development of recapture strategies for minimising potential impacts from cod escapees to ensure sustainable farming activity. [ABSTRACT FROM AUTHOR]

Gilthead sea bream ( Sparus aurata L.) aquaculture has rapidly spread around the Mediterranean Sea. Fish escapes from sea cages are one of the major problems for the industry and also represent a threat to the marine environment. Fishery catches are also influenced by escape events, being mirrored in increased landings of cultured species. However, within the Mediterranean, studies shedding light on the incidence of escaped individuals in fisheries landings are scarce. Firstly, the present study describes a simple scale-examination methodology to distinguish escaped from wild S. aurata landed by coastal fisheries. Secondarily, the incidence of escapees is assessed within landings of the species in the western Mediterranean. The scale readings revealed a monthly incidence of escapees between 11.2 and 20.8%, representing 6.8% of the total income derived from these landings. Moreover, morphological differences between wild fish captured near and far from fish farms point towards escape events as a source of potential genetic admixture between cultured and wild genotypes. Socio-economic and ecological implications of escapees are discussed, and a set of management guidelines proposed, to prevent and/or mitigate the negative influences of escaped fish on the ecosystem and traditional users of the coast such as fisheries. [ABSTRACT FROM AUTHOR]

Trace elements in otoliths of sea bass ( Dicentrarchus labrax L.) and sea bream ( Sparus aurata L.) from fish farms and coastal wild populations in the western Mediterranean Sea were analysed by inductively coupled plasma-mass spectrometry. Results showed that concentrations of Mg, K, and Mn differed significantly between wild and farmed sea bass, while concentrations of Mg, K, Mn, Fe, Zn, Sr, and Ba varied significantly between wild and farmed sea bream. Discriminate analysis and cross-validation classification showed that the trace element profile in otoliths can be used to separate farmed fish from wild stocks with high accuracy on both sea bass (individuals correctly classified: 90.7 %) and sea bream (individuals correctly classified: 96.6 %). Moreover, trace elements in otoliths resulted to be useful to discriminate among wild fish stocks within each species. [ABSTRACT FROM AUTHOR]

Escape incidents in coastal aquaculture lead to economic losses for farmers and may have indirect socioeconomic effects on local fisheries. In this study, the relationship of meagre, Argyrosomus regius (Asso), production in open-sea cages and coastal small-scale fisheries was analysed through captures of escapes, which are easily detected because this species is considered locally absent in native communities in Western Mediterranean regions. Scale reading showed that 100% of captured meagre were escapees. The existence of a direct relationship, in terms of biomass, between the development of meagre coastal aquaculture and the increase of captures of this species by local fisheries was demonstrated. The spatial distribution of meagre captures suggested that there is a local environmental and economic interaction between meagre aquaculture and fisheries through escapees. Monitoring the presence of locally absent species such as meagre within landings might help to assess the magnitude of escapes, the potential economic effects on local aquaculture and fishery industries, and the potential adverse ecological impacts on local ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Escapes of cultured gilthead seabream (Sparus aurata L.) have been recorded throughout the Mediterranean Sea. In the current study we simulated escape incidents of seabream tagged with acoustic transmitters (N =38) or external tags (N =2191). Tagged individuals showed both a high dispersion within the first 5 days after release and a high mortality rate (>60%) where the fish appeared to be predated at the release farm. However, some individuals remained not only at the release farm but also at the nearby farm facilities for long periods, surviving up to 4 weeks with a clear diurnal swimming depth behaviour related to farm activity. Local fisheries contributed largely recapturing tagged individuals that disperse from farm facilities (7.25%), being professional trammel-netters the major contributors (71.5%). Those recaptured individuals were caught on usual fishing grounds and habitats where their wild conspecific live (seagrass, sand or rocky bottoms), feeding on natural preys such as crustaceans and molluscs after one week in the wildness. Therefore, our findings emphasize the negative ecological consequences that escapees might entail to nearby cultured and wild stocks, and the importance of local fisheries to reduce the potential effects of escape incidents on natural stocks. [Copyright &y& Elsevier]

The study of mass and standard length ( LS) relationships showed that farmed individuals had higher values than wild fishes for both gilthead sea bream Sparus aurata and European sea bass Dicentrarchus labrax. Such differences were more pronounced in larger individuals than smaller ones and were more noticeable in S. aurata than in D. labrax. Additionally, differences in external characteristics of scales were detected between origins. A high proportion of farmed S. aurata had a regenerated nucleus (98%) and scale malformations (73%), and there were no annual rings in the farmed D. labrax (100%). Variation in otolith morphology was examined through shape descriptors such as area, perimeter, circularity, roundness, mass, height and length relationship and elliptic Fourier descriptors (EFDs). Important differences were found within geographical origins according to each shape descriptor separately, but no clear patterns distinguished wild and farmed fish. Discriminant analysis with either all shape descriptors together or EFDs was able to classify with high accuracy both S. aurata (89·5-95·7%) and D. labrax (93·2-95·2%) according to their origin. Hence, this study suggests the use of scale characteristics as the easiest and quickest way to distinguish farmed or escaped fishes, and secondly, the usefulness of EFDs or shape descriptors to improve such separation. [ABSTRACT FROM AUTHOR]

Gilthead seabream ( Sparus aurata L.) and European seabass ( Dicentrarchus labrax L.) are important commercial marine fish species both for aquaculture and fisheries in the Mediterranean. It is known that farmed individuals escape from farm facilities, but the extent of escape events is not easy to report and estimate because of the difficulty to distinguish between wild and farmed individuals. In this study, significant differences provided through morphometry evidence that the cranial and body regions of seabream and seabass are different regarding their farm or wild origin at different scales. Morphological variations have been shown to be a valuable tool for describing changes in shape features. Therefore, the biomass contribution of escapees to local habitats could be determined by identifying escaped individuals from fisheries landings as a first step to assess the potential negative effects of fish farm escapees on the environment, and their influence on wild stocks and local fisheries. [ABSTRACT FROM AUTHOR]