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Extractive fisheries and marine aquaculture share space and target species. Several regional-scale examples exist of escapees entering wild fisheries landings, yet no study has assessed the influence of aquaculture on landings at an ecosystem scale. We examined the effects of farmed fish escapes on fisheries using FAO data and published escape rates for Gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax). Seabream landings were significantly correlated with the estimated biomass of escaped seabream entering the wild. There was a similar pattern for seabass until 2005, but the overall relationship between landings and escapes was not significant due to the dramatic drop in catches in recent years. We argue that seabass escapees' relatively high mortality, lower capturability, and minor 'leaking' from farms may obscure their influence on landings. Significant positive fisheries regime shifts were detected for both species, matching the onset of aquaculture in the Mediterranean and the period when escapees from aquaculture surpassed landings. Our results suggest that fish escapes of these two iconic species may mask wild stock overexploitation, confound stock assessments, alter genetic diversity, increase the risk of spreading pathogens and parasites, and compete with wild conspecifics while boosting fisheries landings., (© 2024. The Author(s).)

Wild fish belonging to four species belonging to different trophic groups were captured at three distances from fish farm facilities: long distance (>5 Km), medium distance (1.5 Km) and close to sea-cages. Flesh, brain, liver and gonads were sampled for fatty acid analysis. Fish aggregated near sea-cages showed accumulation of fatty acids of vegetable origin in the studied tissues, due to surplus feed consumption or via predation of fish that consumed the feed. Gonads accumulated vegetable fatty acids in different manner in the different species, and the species least and most influenced by fish-feeds were selected for gonad histological examination. Results showed an acceleration of the final stages of the oocyte development in fish aggregated near fish farms compared to fish captured at long distance. Differences in oocyte development were more acute in the species which incorporated higher quantities of vegetable fatty acids., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

We investigated the changes on the mean trophic level of fish assemblages across different spatiotemporal scales, before and after a massive escape event occurred off La Palma (Canary Islands), which resulted in the release of 1.5 million fish (mostly Dicentrarchus labrax) into the wild. The presence of escaped fish altered significantly the mean trophic level of fish assemblages in shallow coastal waters. This alteration was exacerbated by the massive escape. A nearby marine protected area buffered the changes in mean trophic level but exhibited the same temporal patterns as highly fished areas. Moreover, escaped fish exploited natural resources according to their total length and possibly, time since escapement. New concerns arise as a "farming up" process is detected in shallow coastal fish assemblages where marine aquaculture is established., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Interannual variability (2003-2008) of meiofaunal assemblages were analyzed in sediments beneath fish cages (Impact group) and in areas not affected by aquaculture activities (Control group). Organisms responded with spatial and seasonal variation in meiofauna assemblages, with an abrupt increase of abundances in locations beneath fish cages throughout the study period. This increase was greater during the last sampling year (2008) and mainly due to high abundances of nematodes. Univariate analyses showed differences between control and impacted sites at both sites, however, only significant variations were found in Los Gigantes, which are consistent with seasonal meiofauna variations throughout the study period. These results are partially explained by differences in current velocity between both sampling areas. The Ne/Co index showed the same trend and it seems to be a reliable index in sediment slightly affected by aquaculture wastes. This index is especially recommended in oligotrophic areas (e.g. Canary Islands) where meiofaunal assemblages are poorly represented in terms of abundances., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

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.

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]

Escape incidents of farmed fish involve economic losses to fish farms, interactions with local fisheries and environmental impacts to coastal ecosystems. More attention should clearly be paid to preventive measures. It is also essential to develop and establish contingency plans in case of escapes, to mitigate potentially negative socioeconomic and environmental impacts. Three mark-and-recapture experiments simulating escape incidents of sea bass (N = 1000 ind.), sea bream (N = 1000 ind.) and meagre (N = 1000 ind.) were carried out at three coastal fish farms located along the Mediterranean Coast of Spain. First, targeted experimental fishing trials in collaboration with artisanal netters were attempted at each location as potential fast-response contingency plans for recapturing escapees. Targeted fishing was successful on meagre (N = 38 ind., CPUE: 2.2 ind 10 m −2 h −1 ) and sea bream (N = 8 ind., CPUE: 1.3 ind 10 m −2 h −1 ), while no sea bass were recaptured. Secondly, recaptures reported from local fishermen (professional and recreational) during the study period were also considered. Altogether, total recapture rates were similar among the three species (sea bass: 5.4%; sea bream: 7.1%; meagre: 8.7%), although the spatial and temporal observations of recaptures varied among species. Recreational fishermen were the only contributors, recapturing 54 tagged sea bass (angling: 85%; spear-fishing: 15%) in mainly shallow coastal waters and about three km distance from the fish-farm during the weeks after release. A total of 71 escaped sea bream were recaptured by both recreational and artisanal fishermen, contributing similarly (recapture rates: 47.9% and 40.8% of total, respectively). Most sea bream recaptures were during the first nine days after release (86% of total recaptures), mainly near the farm facilities (<3 km). The bulk of meagre recaptures were during the first two days after release (>95%), mainly by experimental and artisanal netting (38 and 47 individuals respectively) again near the facility. In parallel, an underwater visual census was carried out at coastal locations and Natura 2000 sites in each study area, to assess the presence of escapees in marine habitats of special interest. Neither escaped sea bass nor escaped meagre were observed during underwater surveys, and only three tagged sea bream were found together at artificial reefs. Given that recaptures of tagged fish differed among fish species and fishing techniques following simulated escape incidents at W-Mediterranean coastal facilities, diverse potential contingency plans are here discussed. [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]

Currently, the lipid content of fish feeds includes high amounts of terrestrial vegetable oils, rich in n-6 fatty acids and poor in n-3 fatty acids. Sinking organic matter in the shape of fragmented pellets and fish faeces could be ingested by the surrounding fauna attracted to the submerged structures of aquaculture facilities or living in natural benthic habitats. Fatty acids contained in feed pellets were used as trophic markers to shed light on the assimilation and incorporation of aquaculture wastes by the invertebrate fauna associated to sea-cages. Eighteen macroinvertebrate species, and zooplankton, seaweeds and sediments were collected from two fish farms, one of which (control) had not been used as such for two years. This study demonstrates that macroinvertebrate fauna present in fouling can take up sinking organic matter from farms. Further research should be directed at assessing the potential implications of aquaculture production for the surrounding ecosystem. [ABSTRACT FROM AUTHOR]

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]

The article discusses research which aims to assess the impact of sea bass and sea bream coastal farming on peracarid assemblages in three Mediterranean fish farms in Spain. Data collection details are described which include punctual sampling, gathering of three random replicates in each fish farm, and sediment analysis. Univariate and multivariate statistical methods have been used to evaluate peracarid assemblage differences in control areas and farms being studied. It is reported that amphipod gammarids were the most abundant group observed in the assemblages following tanaids.

Artificial reefs (ARs) have become an important tool to increase the ichthyofauna associated with artisanal and commercial fishing. Integrated evaluations of ARs are necessary to comprehend the condition and benefits of these structures. Multimetric indices (ARMIs) were developed to evaluate fish assemblages associated with artificial structures and to assess the efficiency of the AR compared to control area (CA). The AR global ranking index (ARMI r) and AR local effect index (ARMI e) include 16 metrics that represent four broad levels of the fish community: structure of fish assemblages, trophic structure, vulnerability and economic importance. Individual metrics were evaluated using a long-term dataset of fish assemblages from the AR and CA in northern Rio de Janeiro, Brazil. Bottom gillnets were used to sample the fish two times per year for 21 years after creating the reef. The ARMI r general score for the AR was 51 out of a possible 100, with scores varying from 38 to 54. The ARMI r general score for the CA was 39 out of 100, with scores varying from 35 to 47. Average ARMI e values were 12% higher for the AR in relation to the CA. Spatial-temporal comparisons of the ARMI r using generalized additive models revealed significant differences between AR and CA. Evaluations of the ARMI e scores revealed that the assemblage structure and economic importance level significantly increased over time in the AR. The proposed indices combine structural and functional levels of fish, providing a robust and sensitive method to evaluate the ecological condition of ARs and adjacent areas. The data contribute to discussions related to ARs management and provides a baseline for defining fish assemblage metrics in assessment of localities with artificial structures. Image 1 • Multimetric indices were developed for assessing fish assemblages at artificial reef. • Metrics were selected based on ecological and economics aspects of fish assemblages. • The newly indices discriminates both artificial reef and control area. • These indices have potential to be used in the management of artificial reefs. [ABSTRACT FROM AUTHOR]

Escape incidents of farmed fish involve economic losses to fish farms, interactions with local fisheries and environmental impacts to coastal ecosystems. In order to ensure a sustainable aquaculture activity it is advisable to gather any kind of information about the escapees for further management strategies. In this study, we aimed to trace the life history of escaped meagre (Argyrosomus regius) through otoliths microchemistry, based on the assumption that escaped fish experience different environmental conditions once they are outside the net-pen compared to their farmed conspecifics. Strontium (Sr88) and barium (Ba138) composition was analyzed using laser-ablation ICP-MS along core-to-edge transects of right sagittal otoliths on escaped and farmed meagre from the same coastal area in the W-Mediterranean Sea. Overall, results showed similar patterns of Sr concentrations throughout the otolith transects between farmed and escaped meagre, although some differences can be observed at specific periods of fish life for Ba concentrations. Consequently, temporal variations regarding otolith Sr:Ba ratios differed between farmed and escaped meagre, suggesting that farmed and escaped fish shared the same origin (rearing at coastal farms) but inhabited in different conditions from a certain time of their life. However, core-to-edge Sr:Ba values also differed among escaped individuals, which might indicate that each individual escaped in different periods. Consequently, the otolith Sr:Ba ratio seemed to be a good indicator of differences between fish groups, showing different temporal patterns. Nevertheless, the limitation of the low number of sampled individuals prevented to draw clearer conclusions. Further research is necessary in order to investigate the potential use of otolith microchemistry as a practical tool to trace of escaped fish, and consequently, to help solving potential conflicts among coastal users improving management of potential negative socioeconomic and ecological impacts. • Escaped meagre experience different environmental conditions in the wild. • Sr and Ba compositions revealed temporal variations along the otolith transect. • Core-to-edge otolith Sr:Ba ratios differed between escaped and farmed meagre. • Otolith microchemistry might help to trace the life-history of escaped fish. [ABSTRACT FROM AUTHOR]