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Simple Summary: After a decade of research about the use of insects as fish feed, this paper reports the results of a large-scale trial on European sea bass (Dicentrarchus labrax) farmed under commercial conditions. Fish were fed an experimental diet containing 10% Hermetia illucens larva meal, 30% poultry by-product meal, and <5.5 g/100 g of feed of marine proteins. The results highlight that fish growth performances and the flesh quality of sea bass fed the experimental diet were similar to those of fish fed a commercial diet containing fish meal and fish oil. This study suggests that a diet rich in plant proteins, in which H. illucens and poultry by-products are also included, may be a viable alternative to existing aquafeeds for marine species. Protein meals from insects in combination with poultry by-product meal appear to be promising ingredients for replacing conventional proteins in the diets of carnivorous fish. The present study explored the effects on growth performance, hepatic enzymatic activity, and fillet physical and nutritional characteristics during a 66-day feeding trial performed on European seabass. A total of 3000 fish were distributed into three tanks, where the control group was fed with a commercial diet (CG) and a second group was fed in duplicate with the experimental diet (SSH) containing 10% Hermetia illucens larva meal, 30% poultry by-product meal, and <5.5 g/100 g of feed of marine origin proteins. All fish showed good growth performance. Glucose-6-phosphate dehydrogenase, aspartate aminotransferase, and 3-hydroxyacyl-CoA dehydrogenase activities were higher in the SSH group than in the CG group. The fillet fatty acid profile was largely unaffected by diet, except for a few fatty acids. Fish fed the SSH diet had a lower C22:1n-11 content than CG, thus suggesting an increased β-oxidation. The oxidative status of muscle lipids was not affected by the diet. In conclusion, the present study showed that European seabass can be successfully fed the SSH diet for two months in a commercial setting. [ABSTRACT FROM AUTHOR]

Simple Summary: This study focuses on the use of high-quality and sustainable feed ingredients, derived from circular bioeconomy processes, as major components of new diets for Gilthead sea bream and European sea bass, the most important farmed fish in the Mediterranean basin. In this study, we investigated the effects of replacing dietary plant proteins with insect and poultry by-product meals on the liver health of sea bream and sea bass through histological and biochemical analyses. Four diets were tested, including a control fish meal-free diet, based on plant-derived ingredients, and three other ones, in which 40% of the plant protein was replaced with Hermetia illucens and poultry by-product meals. The results revealed distinct responses to the test diets between sea bream and sea bass, in terms of biometric parameters, lipid metabolism, and liver condition. Sea bream utilized dietary nutrients efficiently, adapting to the test diets in terms of weight gain, physiological well-being, and liver health. Conversely, the test diets led to significant hepatic lipid accumulation in sea bass, resulting in an increased risk to liver health. The liver health of Gilthead sea bream and European sea bass, fed with fish meal-free diets, including various proportions of plant proteins, as well as insect and poultry by-product meals, was investigated through biochemical and histological analyses using a new liver index (LI) formula. Four isoproteic (45% Dry Matter, DM) and isolipidic (20% DM) diets were compared, including a plant-based control diet (CV) and three other test diets, in which 40% of a plant protein-rich ingredient mixture was replaced with meals from Hermetia illucens (H40) or poultry by-product (P40) alone, or in combination (H10P30). The trials lasted 12 and 18 weeks for sea bream and sea bass, respectively. The results obtained thus far highlighted species-specific differences in the physiological response to dietary changes. In sea bream, the biochemical and histological responses suggest favorable physiological and liver health statuses, with higher serum cholesterol (CHO) and triglyceride (TAG) levels, as well as moderate hepatocyte lipid accumulation, with the H10P30 diet compared to the CV (p < 0.05). In sea bass, all diets resulted in elevated serum TAG levels and lipid accumulation in the liver, particularly in fish fed the P40 one (p < 0.05), which resulted in the highest LI, coupled with a higher frequency of severe lipid accumulation, hypertrophy, cord loss, peripheral nuclei displacement, and pyknosis. In conclusion, sea bream adapted well to the test diets, whereas sea bass exhibited altered hepatic lipid metabolism leading to incipient liver steatosis, likely due to the high lipid contents of the diets, including the insect and poultry meals. The LI formula developed in this study proved to be a reliable tool for assessing the effects of dietary changes on the liver health of sea bream and sea bass, consistent with biochemical and histological findings. [ABSTRACT FROM AUTHOR]

Importation and translocation of seeds and live animals for aquaculture purposes are well-established practices in the European and Italian shellfish market. However, these routines may be responsible for alien species introduction and spread, representing a risk for aquaculture activities, human health, as well as for environmental and biodiversity conservation. To estimate and reduce the potential impact of alien and locally absent species on aquatic habitats due to aquaculture practices, Member States have adopted Council Regulation (EC) No 708/2007, which provides guidance for risk analysis and contingency measures for mitigation. Despite this legal framework, traceability data for shellfish movements are currently lacking and need to be improved in all EU Member States. The present work presents an updated literature summary of alien species associated with bivalve farming and trading. The information herein collected will be helpful to upgrade the traceability system of farmed bivalves in Italian marine waters with reference to non-target species, representing a knowledge baseline for setting bio security plans to reduce their risk of introduction and further spreading. [ABSTRACT FROM AUTHOR]

Simple Summary: Processed animal proteins, such as poultry by-product meal (PBM) and insect meal from black soldier fly (BSFM), are receiving growing interest as alternative or complementary protein sources for carnivorous farmed fish diets, due to their high nutritional value and low environmental footprint. The present study aimed to evaluate the effects of PBM and BSFM as partial substitutes for vegetable protein in fishmeal-free diets on growth, whole-body composition, nutrient-energy mass balance and retention, digestive functions, stress, metabolic status, innate immunity, and liver health in rainbow trout (Oncorhynchus mykiss). The overall results showed that fishmeal-free diets, including high levels of both PBM and BSFM, either singly or in combination, improved growth, dietary nutrient and energy utilization, and gut function relative to a plant-protein control diet or a fishmeal-based one, with no detrimental effects on fish welfare. This study compared the nutrient-energy retention, digestive function, growth performance, and welfare of rainbow trout (ibw 54 g) fed isoproteic (42%), isolipidic (24%), fishmeal-free diets (CV) over 13 weeks. The diets consisted of plant-protein replacement with graded levels (10, 30, 60%) of protein from poultry by-product (PBM) and black soldier fly H. illucens pupae (BSFM) meals, either singly or in combination. A fishmeal-based diet was also tested (CF). Nitrogen retention improved with moderate or high levels of dietary PBM and BSFM relative to CV (p < 0.05). Gut brush border enzyme activity was poorly affected by the diets. Gastric chitinase was up-regulated after high BSFM feeding (p < 0.05). The gut peptide and amino acid transport genes were differently regulated by protein source and level. Serum cortisol was unaffected, and the changes in metabolites stayed within the physiological range. High PBM and high BSFM lowered the leukocyte respiratory burst activity and increased the lysozyme activity compared to CV (p < 0.05). The BSFM and PBM both significantly changed the relative percentage of lymphocytes and monocytes (p < 0.05). In conclusion, moderate to high PBM and BSFM inclusions in fishmeal-free diets, either singly or in combination, improved gut function and nutrient retention, resulting in better growth performance and the good welfare of the rainbow trout. [ABSTRACT FROM AUTHOR]

Summary: The Atlantic bluefin tuna (ABFT), Thunnus thynnus (Linnaeus, 1758), is an important commercial species managed as two different stocks, western and eastern Atlantic, with their spawning grounds in the Gulf of Mexico and in the Mediterranean Sea, respectively. The eastern Atlantic stock has been overexploited in the last decades, leading to the application of specific management measures introduced by the International Commission for the Atlantic Tuna (ICCAT). A clear understanding of the genetic structure of ABFT Mediterranean population should be pursued in order to support management decisions. To date the genetic studies on the Mediterranean ABFT, carried out with different molecular markers and sampling procedures, have produced unclear results. Here, we analysed ABFT samples from central and western Mediterranean Sea with mitochondrial sequences and 11 microsatellite loci to investigate, among the others, the area of the Strait of Messina, where environmental conditions seem to support a resident population of ABFT. Furthermore, genetic analyses of mitochondrial sequences were carried out including nucleotide sequences of Adriatic ABFT wild larvae retrieved from GenBank. Among the investigated areas a genetic differentiation was detected between the Strait of Messina and the Tyrrhenian Sea with microsatellite loci according to the exact G test, but not to the Bayesian analyses carried out with STRUCTURE. The analyses with mitochondrial sequences do not reveal any differentiation among sampled areas, however, a highly significant genetic divergence was observed between the Adriatic mitochondrial sequences retrieved from GenBank and the central‐western Mediterranean sequences obtained in the present work. Our results provide some evidence of population structure of Mediterranean ABFT adding pieces to a still unclear picture. [ABSTRACT FROM AUTHOR]

To meet the Convention on Biological Diversity's Aichi Target 11 on marine biodiversity protection and Aichi Target 6 on sustainable fisheries by 2020, as well as the Sustainable Development Goal (SDG) 2 on food security and SDG 14 on oceans by 2030, there is an urgent need to rethink how best to reconcile nature conservation and sustainable development., This paper argues for effective governance to support processes that apply principles of sustainable development and an ecosystem approach to decide about economic activities at sea such as aquaculture. It describes opportunities, benefits and synergies between aquaculture and MPAs as a basis for wider debate. The scope is not a comprehensive analysis of aquaculture and MPAs, but rather to present examples of positive interactions between aquaculture activities and MPAs. The unintended negative consequences are also discussed to present balanced arguments., This work draws from four workshops held in 2015 and 2016 and used to collect information from about 100 experts representing various sectors and perspectives., It is recognized that aquaculture is an important activity in terms of sustainable development. It can play a role in providing food security, poverty alleviation and economic resilience, in particular for MPA local communities, and contribute to wild stock enhancement, as an alternative to overfishing and for providing services to the ecosystem., This study showed that there is a need from both aquaculture and MPA sides for clarity of objectives and willingness for open and extensive dialogue. The paper concludes by describing a number of tools and methods for supporting greater synergies between aquaculture and MPAs., The results from this work have already helped to build a common understanding between conservation and aquaculture and initiate a rapprochement for increasing synergies. [ABSTRACT FROM AUTHOR]

The EU Marine Strategy Framework Directive 2008/56/EC (MSFD) defines a framework for Community actions in the field of marine environmental policy in order to achieve and/or maintain the Good Environmental Status (GES) of the European seas by 2020. Microbial assemblages (from viruses to microbial-sized metazoa) provide a major contribution to global biodiversity and play a crucial role in the functioning of marine ecosystems, but are largely ignored by the MSFD. Prokaryotes are only seen as “microbial pathogens,” without defining their role in GES indicators. However, structural or functional prokaryotic variables (abundance, biodiversity and metabolism) can be easily incorporated into several MSFD descriptors (i.e. D1. biodiversity, D4. food webs, D5. eutrophication, D8. contaminants and D9. contaminants in seafood) with beneficial effects. This review provides a critical analysis of the current MSFD descriptors and illustrates the reliability and advantages of the potential incorporation of some prokaryotic variables within the set of indicators of marine environmental quality. Following a cost/benefit analysis against scientific and economic criteria, we conclude that marine microbial components, and particularly prokaryotes, are highly effective for detecting the effects of anthropogenic pressures on marine environments and for assessing changes in the environmental health status. Thus, we recommend the inclusion of these components in future implementations of the MSFD. [ABSTRACT FROM AUTHOR]

Among the behavioural factors affecting survival of hatchery-reared fish when released into the wild, inefficient foraging is considered to be a major behavioural deficit. The present study investigates the ability of hatchery-produced, pellet-reared dusky grouper Epinephelus marginatus juveniles to recognize and catch live prey (sea bass Dicentrarchus labrax fingerlings 30-80 mm TL) and analyses the effects of a training period on their foraging performance. Juvenile E. marginatus (3+ years, 270-330 mm TL) showed an innate ability to recognize and capture live D. labrax fingerlings as latency time to first attack was very short (<1 min). Older and larger-sized juvenile E. marginatus (4+ years, 350-400 mm TL) are not immediately able to recognize live D. labrax as preys and no attack was observed in the first 2 days. A 10 day training period involving live preys improved foraging performance in both younger and older juveniles. The effect was more evident for older E. marginatus in which the ability to recognize prey increased and the latency time to first attack and to first successful attack with experience decreased. For both groups, training also increased the total number of lunges, number of successful lunges and consequently the number of preys eaten. Training should be performed using appropriate sized prey, since smaller-sized E.marginatus prefer smaller preys. Thus, although prey recognition and capture seem to be innate, experience of live prey improves the foraging performance of hatchery-reared E. marginatus of different age-size classes. [ABSTRACT FROM AUTHOR]

Background: Water temperature greatly influences the physiology and behaviour of teleost fish as other aquatic organisms. While fish are able to cope with seasonal temperature variations, thermal excursions outside their normal thermal range might exceed their ability to respond leading to severe diseases and death. Profound differences exist in thermal tolerance across fish species living in the same geographical areas, promoting for investigating the molecular mechanisms involved in susceptibility and resistance to low and high temperatures toward a better understanding of adaptation to environmental challenges. The gilthead sea bream, Sparus aurata, is particularly sensitive to cold and the prolonged exposure to low temperatures may lead to the “winter disease”, a metabolic disorder that significantly affects the aquaculture productions along the Northern Mediterranean coasts during winter-spring season. While sea bream susceptibility to low temperatures has been extensively investigated, the cascade of molecular events under such stressful condition is not fully elucidated. Results: In the present study two groups of wild sea bream were exposed for 21 days to two temperature regimes: 16 ± 0.3°C (control group) and 6.8 ± 0.3°C (cold-exposed group) and DNA microarray analysis of liver transcriptome was carried out at different time points during cold exposure. A large set of genes was found to be differentially expressed upon cold-exposure with increasingly relevant effects being observed after three weeks at low temperature. All major known responses to cold (i.e. anti-oxidant response, increased mitochondrial function, membrane compositional changes) were found to be conserved in the gilthead sea bream, while, evidence for a key role of unfolded protein response (UPR) to endoplasmic reticulum (ER) stress, during short- and long-term exposure to cold is reported here for the first time. Conclusions: Transcriptome data suggest a scenario where oxidative stress, altered lipid metabolism, ATP depletion and protein denaturation converge to induce ER stress. The resulting UPR activation further promotes conditions for cell damage, and the inability to resolve ER stress leads to severe liver dysfunction and potentially to death. [ABSTRACT FROM AUTHOR]

The present paper shows the multidisciplinary approach used to assess the eco-toxicity of chemical munitions lying on the seabed in the Southern Adriatic Sea where aerial bombs charged with mustard agent and organoarsenlc chemical war-fare agents (CWAs) have been dumped. Sampling activities and laboratory analyses have been carried out on two sen-tinel species, the blackbelly rosefish, Helicolenus dactylopterus, and the European conger, Conger conger, collected in a CWA dumping site 35 nm from the coast of Apulia, Italy, and from a reference site. Fish were analyzed through an ecotoxicolo-gical approach, integrating chemical analysis and biological responses. Degradation products of the blister agents ö/s-(2-chloroethyl)sulphide, com-monly known as mustard agent or yperite (also called sulfur or sulfur mustard), were found in sediment samples collected nearby aerial bombs. Although no evi-dence of these compounds was detected in tissues of either fish, levels of heavy metals (arsenic and mercury), potentially released by rusted chemical weapons, were significantly higher in sediment and fish from the CWA site compared to the reference site. Severe external and internal lesions were observed in fish captured in the CWA site, with congers displaying small to large skin ulcers along the body. Health assessment index (HAI) values, as well as spleen melano-macrophages cen-tres and CYP1A ethoxyresorufin-Odeethylase activity were higher in fish from the CWA site, indicating a chronic state of illness and environment degradation. The working procedures and analyses performed during these surveys could be suitable for future biomonitoring studies in other CWA dumping sites. [ABSTRACT FROM AUTHOR]

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The dusky grouper (Epinephelus marginatus) is an endangered marine fish for which a restocking program has been undertaken in the Mediterranean Sea. Genetic variation at six microsatellite loci was assayed to help plan preservation of genetic diversity after release of hatchery-reared juveniles. We estimated relatedness and effective population size within two groups of captive broodstock, assessed genetic variability of these broodstock and F1 juveniles compared to natural populations, and investigated genetic relationships between hatchery-reared and wild specimens inhabiting the release site. On average, no relatedness was found within captive broodstock and a potentially high number of effective breeders was assessed (Nb = 86.9; CI 95% = 46.0-451.2). However, very few breeders (N = 7) spawned successfully, and a positive degree of relatedness (rW = 0.0297) was found among this particular subset of individuals. Genetic variability parameters were reduced for the broodstock and F1 juveniles, although not significantly. Genetic differentiation was detected among released juveniles and wild conspecifics collected 75 km away from the target area. However, the pattern of genetic distances from other wild populations justifies the choice of the broodstock as the best alternative donor stock. [ABSTRACT FROM AUTHOR]

Sustainability of aquaculture is tied to the origin of feed ingredients. In search of sustainable fish meal-free formulations for rainbow trout, we evaluated the effect of Hermetia illucens meal (H) and poultry by-product meal (P), singly (10, 30, and 60% of either H or P) or in combination (10% H + 50% P, H10P50), as partial replacement of vegetable protein (VM) on gut microbiota (GM), inflammatory, and immune biomarkers. Fish fed the mixture H10P50 had the best growth performance. H, P, and especially the combination H10P50 partially restored α-diversity that was negatively affected by VM. Diets did not differ in the Firmicutes:Proteobacteria ratio, although the relative abundance of Gammaproteobacteria was reduced in H and was higher in P and in the fishmeal control. H had higher relative abundance of chitin-degrading Actinomyces and Bacillus, Dorea, and Enterococcus. Actinomyces was also higher in H feed, suggesting feed-chain microbiome transmission. P increased the relative abundance of protein degraders Paeniclostridium and Bacteroidales. IL-1β, IL-10, TGF-β, COX-2, and TCR-β gene expression in the midgut and head kidney and plasma lipopolysaccharide (LPS) revealed that the diets did not compromise the gut barrier function or induce inflammation. H, P, and H10P50 therefore appear valid protein sources in fishmeal-free aquafeeds. [ABSTRACT FROM AUTHOR]