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Abstract Exercise training in fish leads to enhanced growth, mostly in salmonids, but also in gilthead sea bream (Sparus aurata). Most of the published studies have involved juveniles or adult fish, but little is known about the effects of exercise on early stages of fish growth. Our study aimed to examine the effect of sustained swimming on the growth of gilthead sea bream fingerlings, by analysing white muscle cellularity and capillarisation. Two groups of fingerlings were compared: the exercise group (EX), forced to swim at five body lengths·s−1, and the control group (CT), maintained under still water flow and showing only voluntary swimming. After 5 weeks the EX group had a significantly higher body weight (CT: 17.5 ± 0.46; EX: 20.3 ± 0.38 g, p <.001) without significant differences in muscle-somatic index (CT: 34.9%; EX: 37.3%). The white muscle of EX fish showed significant reductions in fibre cross-sectional area (FCSA) and fibre perimeter (FPER), by 21% (p <.05) and 10% (p <.0.5) respectively, with no differences in fibre circularity. The number of small fibres (with FCSA <2000 μm2) was significantly (p <.05) higher in the EX than in the CT group. Therefore, the distribution of FCSA demonstrated an increase in hyperplasic processes in EX fish. Total muscle capillary density (CD) and the capillarisation of individual fibres (expressed as the number of capillaries per unit FCSA) of the EX group also increased significantly (p <.05 and p <.001, respectively). In summary, sustained aerobic exercise in the early stages of life of gilthead sea bream enhances body growth, increasing total muscle mass by hyperplasia and determining a more aerobic muscle phenotype by increasing individual fibre capillarisation. Highlights • Gilthead seabream fingerlings enhance growth and total muscle mass under moderate and sustained exercise. • In exercised muscle, a greater number of small fibres base early growth on hyperplasia processes. • Sustained swimming increases white muscle fibre capillarization [ABSTRACT FROM AUTHOR]

Abstract In this study we carried out an analysis of the relationship between the variation in environmental and oceanographic parameters and the changes in the abundance of blackspot sea bream (Pagellus bogaraveo) in the Strait of Gibraltar between 1983 and 2016. A discrete dynamic model was applied to simulate different scenarios of blackspot sea bream biomass on a monthly time scale. ARIMA models were applied to the simulated biomass time series in order to extract the effect of the fishing component and then correlate the residual series with each of the environmental and oceanic parameter sets. Regardless of the scenario analysed, the error terms provided by the ARIMA models indicated a strong auto-regression dependence on the series and that the fishing component accounted in the worst case scenario for 73% of the variation in sea bream biomass in the Strait of Gibraltar. Throughout the study period, part of the variation not explained by the fishing component was explained in certain years by environmental parameters. These correlations were particularly significant for the water temperature anomaly, salinity anomaly and the NAO index. Our analyses therefore suggest that the main factor responsible for the drastic decline in the abundance of sea bream in the Strait of Gibraltar is over-exploitation of the resource and that environmental conditions had a one-off effect which, depending on the year, favoured or harmed the recovery of the stock. [ABSTRACT FROM AUTHOR]

In order to study the effects of dietary β-glucan (BG), vitamin C (VC) and their combination (BG/VC) on growth, humoral and mucosal immune responses of red sea bream ( Pagrus major ) and its resistance to low water salinity stress, 240 healthy fish with initial body weight of 1.98 ± 0.01 g were randomly divided into four groups: a control group fed with basal diet and three treated groups fed with basal diets supplemented with 1000 mg kg − 1 BG, 800 mg kg − 1 VC, and the combination of 500 mg kg − 1 BG + 400 mg kg − 1 VC, respectively. The obtained results showed that, compared with the control, the final body weight, weight gain and specific growth rate, feed and protein efficiency ratio, body protein content, nitro blue tetrazolium (NBT), total serum protein and tolerance against low salinity stress increased in fish fed BG or/and VC supplementations with the highest being in fish fed both BG and VC supplements while body moisture content, plasma glucose, triglyceride and malondialdehyde (MDA) contents decreased ( P < 0.05); body lipid content, hematocrit, serum and mucus lysozyme activities, superoxide dismutase (SOD), alternative complement pathway and mucus secretion also significantly increased in fish fed BG and VC supplements ( P < 0.05). Moreover, the fish fed BG diet had better improvement ( P < 0.05) in mucus bactericidal activity than the VC group. Furthermore, fish fed BG diet exhibited higher serum peroxidase activity (PA), however, fish fed VC diet showed higher mucus PA than the control group ( P < 0.05). Thus, the basal diet supplemented with BG or/and VC could promote the growth, antioxidant capacity, humoral and mucosal immune responses of red sea bream, and enhance the resistance to low salinity stress. Statement of relevance A combination of β-glucan and vitamin C presented an additive effect on inducing the growth, immune responses and oxidative status of red sea bream. We recommend that treatment of 500 mg of β-glucan and 400 mg of vitamin C per kg diet is the appropriate concentration of inducing the red sea bream immune response. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the pharmacokinetics of flumequine following intraperitoneal administration of 14 C-Flumequine (12 mg/kg, 100 μCi/kg) in sea bream ( Sparus auratus ). Three fish (147 ± 29 g) were collected at various time points ranging from 0.5 h to 144 h post administration. Absorption, distribution and elimination were studied using whole body autoradiography and liquid scintillation counting whereupon the concentration of flumequine equivalent versus time was evaluated in major organs and tissues (liver, bile, heart, brain, blood, kidney, intestine, spleen, red and white muscle). An agreement between the data obtained from whole body autoradiography and liquid scintillation counting was observed. A rapid and extensive distribution of flumequine to the major organs 0.5 h after dosing was recorded. The main route of elimination appeared to be biliary excretion due to the high concentration of radioactivity in the bile and the prolonged elimination phase compared to others tissues. The elimination of flumequine from the blood followed a two compartmental model with half life of the first phase and second phase being 0.98 h and 21.4 h respectively. The maximum flumequine recorded in blood (C max ) was 9.09 mg/kg at 0.78 h (T max ). Only traces of drugs were observed in the major tissues of the fish 72 h after administration. Based on the current results and the elimination in edible tissues in particular, flumequine seems to be an excellent treatment candidate for sea bream. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the efficacy of nucleotide related products on growth, blood chemistry, oxidative stress and growth factor gene expression of juvenile red sea bream. Five experimental diets were formulated to contain 49% protein, 11% lipid and the diet without nucleotide related product supplementation was the control (D1). Nucleotide related products like; nucleoside by-products (NBPs) and inosine were supplemented at 1, 3 and 0.03, 0.1% consecutively with basal ingredients of D1 and named as D2, D3 & D4 and D5 respectively. Experimental diets were fed to triplicate groups of fish for 60 days. Fish fed diet D5 showed significantly the highest final body weight and % weight gain followed by the diet groups D2 and D4. Fish fed control group showed the lowest growth performance and were not differed significantly with diet group D3. Feed conversion ratio and protein efficiency ratio were also significantly higher in diet group D5, whereas the other supplemented group showed intermediate value. A wide variation in some of the blood parameters was observed. In case of oxidative stress parameters, fish fed inosine supplemented diets showed the best conditions because they performed better under oxidative stress conditions as well as had the highest tolerance against oxidation. Among NBP supplemented groups, diet group D2 also showed acceptable conditions of oxidative stress tolerance. Stress resistance against low salinity exposure (LT 50 ) also increased with dietary supplementation and it was significantly the highest in fish fed diet group D5. Total serum protein, serum lysozyme activity and total peroxidase content tended to be higher ( P > 0.05) in NBP and inosine supplemented diet groups. In numerically higher hepatic IGF-1, mRNA expression was found in diet groups D2 and D4. However, IGF-1 and IGF-2 mRNA expressions were not significantly altered by dietary supplementations in the present study. Considering overall performance of the present study, we concluded that inosine and low concentration of NBP (1%) could be effectively used as dietary supplements for better growth and health performance of Pagrus major . Statement of relevance In this study industrial by-products, nucleoside by-products and relatively low cost nucleoside, inosine has been evaluated as potential functional nutrients for marine fish such as red sea bream. Utilization of these functional supplements will help to reduce nucleotide administration cost in fish feed as well as to develop low fishmeal based functional aquafeed in the near future. [ABSTRACT FROM AUTHOR]

Identification, understanding and prediction of the factors that drive species to heightened risk of extinction are important goals for conservation, especially since few areas on the planet remain unaffected by human activities. Global extinction risk assessments of an entire family of ecologically complex marine fishes (family: Sparidae), using the International Union for Conservation of Nature Red List process, showed that 8.6% (13 species) of sparids are threatened. Intense fishing pressure and habitat destruction are the main reasons for the observed population declines. A further 7.9% (12 species) are classified as Near Threatened. The majority of the sparids (69.5%) are assessed as Least Concern, and these tended to have smaller body sizes, more widespread distributions, and shorter life spans. The remaining 21 species (13.9%) are listed as Data Deficient. In addition to presenting the first global assessment of sparid extinction risk, a Random Forest model identified correlates of extinction risk in the Sparidae using 33 biological and threat variables. The model correctly classified up to 90% of Red List category placements and showed complex interactions between intrinsic and extrinsic predictors. Larger body size was the most important predictor of extinction risk. Sparids with greater maximum sizes, ages, and turnover rates are at higher extinction risk. Conversely, lower area of occupancy and depth limit confer elevated risk. This analysis adds to the growing body of predictive extinction risk models in marine fishes and presents an opportunity to identify and mitigate threats affecting similar groups of highly-valued and ecologically important marine fishes. [ABSTRACT FROM AUTHOR]

The RIG-I-like receptors family is a group of cytosolic RNA helicase proteins that can recognize viral RNA via binding to pathogen associated molecular pattern motifs within RNA ligands. A novel vertebrate RLR counterpart named LjMDA5 was firstly identified from the marine fish sea perch Lateolabrax japonicus in this study. The full-length cDNA of LjMDA5 is 3750 bp and encodes a polypeptide of 988 amino acids, containing two N-terminal tandem caspase activation and recruitment domains, a DExH (Asp-Glu-X-His) box domain, an HELICc domain, and a C-terminal domain RIG-I. Phylogenetic analysis showed that LjMDA5 shared the closest genetic relationship with the MDA5 of Larimichthys crocea. Quantitative RT-PCR analysis showed that LjMDA5 was ubiquitously expressed and up-regulated significantly in all selected tissues in vivo post NNV infection. Time course analysis showed that LjMDA5 transcripts significantly increased in spleen and kidney. We found LjMDA5 could be regulated in the sea perch LJB and LJF cell lines after lipopolysaccharide, polyinosinic-polycytidylic acid treatment and NNV challenge. RNA interference experiment indicated that silencing of LjMDA5 significantly increased RGNNV replication and virus production in NNV infected LJF cells. Our results revealed that MDA5 was essential for host defense against NNV, which provided new insights into the function of RLR signaling pathway during NNV infection in fish. [ABSTRACT FROM AUTHOR]

During a 19-week trial, sea bream juveniles were fed with two isonitrogenous and isoenergetic diets in which 75% of the fish meal was replaced by plant protein sources and that only differed in the lipid source: fish oil (FO) or vegetable oil (VO). After the growth period, intestinal pH content, digestive enzyme activities, nutrient absorption capacity and final weight were studied in the pre-feeding stage on the FO or VO diet and also after a dietary change at different animal weights (92 g, 147 g, 233 g), both in the short term and at the end of the trial. Intestinal pH content, alkaline protease, α-amylase and lipase activities and nutrient absorption capacities decreased as the animals grew. Moreover, the VO group tended to have higher alkaline protease and α-amylase activities, whereas lipase activity was higher in the FO group; these changes were significant in small fish. The absorption capacities of essential amino acids were higher than those of non-essential amino acids and d -Glc. Moreover, absorption capacities were higher in small VO animals compared to FO. No changes in growth rate were found at the end of the trial. However, FO animals had a higher growth rate during the first half of the trial after which growth slowed, whereas VO animals grew at a lower but more steady rate throughout the trial. Small animals were not able to adapt their digestive enzyme activities or nutrient absorption capacities to the new or original feeding condition after a short-term dietary change, whereas large animals generally adapted. After 9–15 weeks on the FO diet, animals were able to adapt their protease activity and absorption capacity to the new situation; however, α-amylase activity declined. In contrast, after changing to the VO diet animals up-regulated their nutrient absorption capacities and α-amylase activity whereas alkaline protease activity tended to decrease. At the end of the trial final body weight was not affected by dietary treatment. Statement of relevance “Wash out” or FO diet feeding in early stages and VO later? [ABSTRACT FROM AUTHOR]

Fish populations are often comprised of individuals that use habitats and associated resources in different ways. We placed sonic transmitters in, and tracked movements of, white sea bream ( Diplodus sargus sargus ) in the no-take zone of a Mediterranean marine protected area: the Torre Guaceto marine protected area, (Adriatic Sea, Italy). Tagged fish displayed three types of diel activity patterns in three different habitats: sand, rocky reefs and “matte” of the seagrass Posidonia oceanica . Individuals were more active during the day than at night. Overall, white sea bream displayed a remarkable behavioural plasticity in habitat use. Our results indicate that the observed behavioural plasticity in the marine protected area could be the result of multiple ecological and environmental drivers such as size, sex and increased intra-specific competition. Our findings support the view that habitat diversity helps support high densities of fishes. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) and networks of MPAs are advocated worldwide for the achievement of marine conservation objectives. Although the knowledge about population connectivity is considered fundamental for the optimal design of MPAs and networks, the amount of information available for the Mediterranean Sea is currently scarce. We investigated the genetic structure of the saddled sea bream ( Oblada melanura ) and the level of genetic connectivity between protected and unprotected locations, using a set of 11 microsatellite loci. Spatial patterns of population differentiation were assessed locally (50–100 km) and regionally (500–1000 km), considering three MPAs of the Western Mediterranean Sea. All values of genetic differentiation between locations (Fst and Jost’s D) were non-significant after Bonferroni correction, indicating that, at a relatively small spatial scale, protected locations were in general well connected with non-protected ones. On the other hand, at the regional scale, discriminant analysis of principal components revealed the presence of a subtle pattern of genetic heterogeneity that reflects the geography and the main oceanographic features (currents and barriers) of the study area. This genetic pattern could be a consequence of different processes acting at different spatial and temporal scales among which the presence of admixed populations, large population sizes and species dispersal capacity, could play a major role. These outcomes can have important implications for the conservation biology and fishery management of the saddled sea bream and provide useful information for genetic population studies of other coastal fishes in the Western Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Four isoproteic/isolipidic plant protein-based diets were formulated to assess the lasting effects of feed additives and low fish meal (FM) and fish oil (FO) diet formulations on gilthead sea bream growth performance. FM was included at 23% in the control diet (D1) and at 3% in the other three diets (D2, D3, D4). Added oil was either FO (D1) or a blend of vegetable oils replacing 58% (D2) and 84% (D3, D4 diets) of FO. A commercial sodium butyrate preparation (NOREL, 70-BP) was added to the D4 diet at 0.4%. Each diet was allocated to triplicate groups of juvenile fish fed to satiety over an 8-month feeding trial (May–December). All fish grew efficiently from 15 g of initial body weight to 296–320 g with an overall feed efficiency (FE) of 0.95–1.01, although fish fed D3 and D4 diets showed transient growth impairments over the course of the first four weeks of the trial. Data on biometric indexes, whole body composition, haematology and blood biochemistry revealed a strong effect of sampling time in fish sampled at mid-summer (August) and late autumn (December). In contrast, the diet effect was mostly reduced to a few blood parameters. Low inclusion levels of FM reduced plasma haemoglobin levels (D2, D3), but these effects were reversed by butyrate supplementation (D4). The same phenomena occurred for total cholesterol with the highest circulating concentration of choline and IGF-I in fish fed the D4 diet during their summer growth spurt. At the transcriptional level, gene expression profiling of liver and skeletal muscle with a PCR-array of 87 growth markers provided additional evidence for an overall well-growth condition in all of the experimental groups. Up to 73 genes were found at detectable levels in the liver tissue, but only 13 were differentially expressed. Likewise, 84 genes were actively transcribed in the skeletal muscle, but only nine were differentially expressed in at least one experimental group. Butyrate supplementation reversed the up-regulated expression of inflammatory cytokines (TNFα) and muscle markers of cellular morphogenesis and protein breakdown (CDH15, CAPN3, PSMA5, PSMB1, UBE2N) in the muscle of fish fed the extreme D3 diet. These results support the use of low FM/FO diets alone or supplemented with feed additives, which have the potential to improve or reverse metabolic steady-states. Statement of relevance Butyrate effect on low fish meal/fish oil diets. [ABSTRACT FROM AUTHOR]

Gilthead sea bream ( Sparus aurata L.) is a fish commonly cultivated in the Mediterranean sea in marine cages and recirculating aquaculture systems. Managing such growing systems, requires a growth model to describe the response of the fish to their environment. The dominant predictors of growth, assuming adequate water quality, are fish size, M , water temperature, T , and feed ration, F . Over the past 30 years many experimental studies with gilthead sea bream have been conducted, each providing partial information regarding the growth function G M , T , F , … . In this study an attempt is made to critically review the available information from an aquacultural management point of view, selecting simple sub-models which preserve the essentials of the various processes. It seems that for the practical range of application for gilthead sea bream (first two years of life and sub-optimal (<25 °C) temperatures), growth is exponentially dependent on body size and linearly dependent on both temperature and feed ration. A representative growth model with these features, calibrated with the available data, is proposed. Unlike the more sophisticated, two-term bioenergetic models, the suggested model consists of just one multiplicative term. Final calibration of the growth model for any particular facility may be achieved by on-line adaptation of a few of the model parameters. [ABSTRACT FROM AUTHOR]

Dietary compromises, especially food restrictions, possess species-specific effects on the health status and infection control in several organisms, including fish. To understand the starvation-mediated physiological responses in Edwardsiella tarda infected red sea bream, especially in the liver, we performed a 20-day starvation experiment using 4 treatment (2 fed and 2 starved) groups, namely, fed-placebo, starved-placebo, fed-infected, and starved-infected, wherein bacterial exposure was done on the 11th day. In the present study, the starved groups showed reduced hepatosomatic index and drastic depletion in glycogen storage and vacuole formation. The fed-infected fish showed significant (P < 0.05) increase in catalase and superoxide dismutase activity in relation to its starved equivalent. Significant (P < 0.05) alteration in glucose and energy metabolism, as evident from hexokinase and glucose-6-phosphate dehydrogenase activity, was recorded in the starved groups. Interestingly, coinciding with the liver histology, PPAR (peroxisome proliferator activated receptors) α transcription followed a time-dependent activation in starved groups while PPARγ exhibited an opposite pattern. The transcription of hepcidin 1 and transferrin , initially increased in 0dai (days after infection) starved fish but reduced significantly (P < 0.05) at later stages. Two-color immunohistochemistry and subsequent cell counting showed significant increase in P63-positive cells at 0dai and 5dai but later reduced slightly at 10dai. Similar results were also obtained in the lysosomal ( cathepsin D ) and non-lysosomal ( ubiquitin ) gene transcription level. All together, our data suggest that starvation exerts multidirectional responses, which allows for better physiological adaptations during any infectious period, in red sea bream. [ABSTRACT FROM AUTHOR]

Activities of the main enzymes involved in digestion (pepsin, trypsin, amylase, lipase and alkaline phosphatase) in Sobaity sea bream were studied from hatching up to the juvenile stages (40 days after hatch, DAH). All enzyme activities except for pepsin were detected upon hatching, and their activity subsequently increased with age. Early presence of trypsin and amylase was attributed to a genetically programmed process. Trypsin exhibited fluctuating pattern (with tow peaks at 16 and 30 DAH) triggered by food ingestion and was in response to the diet shifting during the rearing period. Both lipase and amylase activities were enhanced after the onset of the weaning depending upon the microbound diet components. Early presence and incremental trend of alkaline phosphatase from 5th DAH represented early maturation of enterocytes and consequently rapid growth of this species. Pepsin was first detected at 14 DAH and showed a sharp increasing trend up to end of the experiment. Its progressive increase followed by a decrease in trypsin activity after accomplishing weaning exhibited a change in the digestive physiology to reach to an adult-type protein digestion. In conclusion, such early ontogenetic development of the above mentioned enzymes makes it possible to wean Sobaity sea bream larvae earlier than 25 DAH in order to reduce live food usage and improve weaning efficiency. Statement of relevance Obtaining knowledge about digestive physiology makes it possible to quantify the capacity of larvae to digest and absorb different types of nutrients from live feed and/or microbound diets and to understand the right time to conduct weaning in Sobaity sea bream larvae earlier than what has been practiced in hatcheries in order to reduce live food usage and improve weaning efficiency. [ABSTRACT FROM AUTHOR]

The microbial diversity of the population grown on a selective medium for pseudomonads (cetrimide-fucidin-cephaloridine agar – CFC) and volatile organic compound (VOC) profile were determined during storage of gutted sea bream ( Sparus aurata ) at 2 °C. Microbiological and sensory changes were also monitored. Pseudomonas spp. were determined as the predominant spoilage microorganisms of gutted sea bream. A total of 104 colonies were collected from CFC plates and identified by 16S rRNA gene sequence analysis at the following three time intervals: day 1, after four days of storage (day 5) and at the sensory rejection point (day 9). Pseudomonas fluorescens was found as more abundant than the rest Pseudomonas species ( Pseudomonas putida , Pseudomonas vranovensis ), being the only bacterial species detected on CFC at the end of shelf life. VOCs such as 2-ethyl-1-hexanol, 2-methyl-1-butanol, 3-methylbutanal, isoamyl butyrate, ethyl acetate and ethyl esters of propionate, butyrate and isobutyrate increased during storage and constitute potential chemical spoilage indices (CSIs) candidates for freshness/spoilage monitoring throughout storage. [ABSTRACT FROM AUTHOR]

Growth rates and the presence of deformities can be affected by the use of different rearing systems as well as by the different genetic origins of the stocks. At the same time, strategies that involve the development of selection schemes for these traits of economic interest are scarce. In this study the effect of the origin of the broodstock on growth traits and external deformities as well as genetic parameters (heritabilities and genetic correlations) for these traits were estimated at different ages (days post-hatching; dph). For this purpose, a population of farmed gilthead sea bream was obtained from three broodstock of different origins along the Spanish coasts [Cantabrian Sea (CAN), the Atlantic Ocean (ATL) and Mediterranean Sea (MED)] and reared under the same intensive conditions. Parental assignments between breeders and their offspring were carried out a posteriori using a microsatellite multiplex (SMsa1). Juveniles from MED showed the fastest growth while those from ATL showed the slowest growth and the highest incidence of vertebral column deformities. Differences among origins could be explained not only through their different genetic backgrounds but also by environmental conditions in the initial facilities, where different origins were reared separately, and by genotype × environment interactions. Growth traits showed low heritabilities at 163 dph (0.11 ± 0.03) and medium at 690 dph (0.25 ± 0.06 for weight; 0.22 ± 0.07 for length) suggesting that selection at the later age would be more appropriate. Both traits were highly and positively correlated at both ages at the genetic and phenotypic levels. External deformities in the vertebral column as well as in the operculum showed medium–high heritability at both studied ages with higher values at 690 dph (0.56 [0.17–0.69] and 0.46 [0.20–0.90], respectively). These results revealed that the ontogenesis of deformities exhibits a partial genetic basis. Nevertheless, for those in the rest of the head the heritability was close to zero. Initially, positive genetic correlations between growth and deformities in the vertebral column were observed (83% probability of being positive for weight-vertebral column deformity; 81% for length-vertebral column deformity). However, these correlations seem to be negative at 690 dph (94.2% probability of being negative for weight-vertebral column; 80.6% for length-vertebral column). Results confirm that it could be recommended to eliminate deformed fish from a breeding nucleus and later, select on growth. All these findings should be relevant for the establishment of successful breeding programs in the aquaculture of this species. [ABSTRACT FROM AUTHOR]

The regulatory role of arginine vasotocin (AVT) and isotocin (IT) in Cl − secretion was investigated with the short circuit current (Isc) technique in opercular epithelia of killifish ( Fundulus heteroclitus ) and gilthead sea bream ( Sparus aurata ). Sea bream operculum showed ~ 4-fold lower number of Na/K-ATPase immunoreactive cells and ~ 12-fold lower secretory current than the killifish. In sea bream opercular membranes, the basolateral addition of AVT (10 − 6 M) significantly stimulated Cl − secretion, while IT (10 − 6 M) was without effect. In killifish, IT produced an immediate dose-dependent stimulation of Cl − secretion with significant effect at doses ≥ 10 − 7 M and stimulation maxima (∆Isc ~ 25 μA ⋅ cm − 2 ) at 10 − 6 M. The basolateral addition of bumetanide (200 μM) abolished > 75% of the effect of IT on Cl − secretion. In turn, AVT had a dual effect on killifish opercular Isc: an immediate response (~ 3 min) with Isc reduction in an inverted bell-shaped dose–response manner with higher current decrease (− 22 μA ⋅ cm − 2 ) at 10 − 8 M AVT, and a sustained dose-dependent stimulation of Cl − secretion (stable up to 1 h), with a threshold significant effect at 10 − 8 M and maximal stimulation (~ 20 μA ⋅ cm − 2 ) at 10 − 6 M. Both effects of AVT appear receptor type specific. The V1-receptor antagonist SR 49059 abolished Isc reduction in response to AVT, while the specific V2-receptor antagonist (Tolvaptan, 1 μM) abolished the stimulatory action of AVT on Cl − secretion. According to these results, we propose a modulatory role for AVT and IT in Cl − (NaCl) secretion across the opercular epithelium of marine teleost. [ABSTRACT FROM AUTHOR]

A 9-week feeding trial was carried out to evaluate dietary arginine requirement of juvenile red sea bream. Six isonitrogenous and isocaloric diets (50% crude protein and 17.7 kJ g − 1 gross energy) were formulated to contain graded levels of arginine including 1.42, 1.88, 2.22, 2.54, 3.08 and 3.43% of diet (2.84–6.86% of dietary protein), and fed triplicate groups of fish (13.3 ± 0.2 g) to apparent satiation twice daily. At the end of the feeding trial, fish fed ≥ 2.22% arginine showed significantly ( P < 0.05) higher growth than those fed 1.42% arginine. Significant improvement in protein productive value was found at dietary arginine level of 2.54% compared to the fish fed 1.42% arginine. Significant reductions in whole-body and muscle lipid contents were found by increment of arginine level and whole-body protein increased significantly in fish fed 2.22–2.54% arginine compared to those fed 1.42% arginine. Plasma total protein level significantly was increased in fish fed 2.54–3.08% arginine, and alanine aminotransferase activity and glucose level were significantly decreased in fish fed 2.22–2.54% and ≥ 1.88% arginine, respectively, compared to the group fed 1.42% arginine. Significant improvements in lysozyme and myeloperoxidase activities and total immunoglobulin level were obtained by dietary arginine increment. Also, significantly higher total nitric oxide synthase activity was recorded at 3.08% arginine level in comparison to 1.42% arginine. A broken-line regression analysis on weight gain showed that the optimum dietary arginine level is 2.37% of diet (4.74% of dietary protein). [ABSTRACT FROM AUTHOR]

Highlights: [•] Gum arabic+ergothioneine (GAER) retarded nucleotide breakdown and lipid oxidation. [•] GAER coating delayed protein degradation, reduced microbial growth. [•] GAER coating maintained better texture and sensory quality of red sea bream. [ABSTRACT FROM AUTHOR]

The large majority of studies on the genotoxic hazard of PAHs polluted water widely applied the ENA assay as versatile tool in large number of wild and farmed aquatic species. Nuclear abnormalities are commonly considered to be a direct consequence of genotoxic lesions in DNA macromolecule, and such evaluation might be helpful in identifying the genotoxic damage induced by the most harmful PAHs such as B[a]P. Regarding at the fish species subjected to aquaculture, most of the toxicological data come from wild fish and mainly focus on freshwater fish, but very little is known for other marine major aquacultured species. The gilthead sea bream ( Sparus aurata L.) is the most economically important sparid species cultured along the Mediterranean costs, and it has been proved a very sensitive species to acute B[a]P exposure. However, further investigation is needed on several other types of genotoxic assessments, especially for chronic effects. This work was totally based on an in vitro model for chronic toxicity, using long-term S. aurata hepatocytes in primary culture, continuously exposed to low levels of BaP, over a prolonged period of time, to provide evidences for latent toxicity response. We aimed to investigate the kind of nuclear damage in gilthead sea bream hepatocytes continuously exposed to B[a]P sublethal doses. Cells were exposed to several B[a]P concentrations (10 μg/mL, 1 μg/mL, 1 ng/mL, 1 pg/mL) for two exposure times (24 and 72 h), and then tested both for apoptosis induction and for nuclear abnormalities by immunofluorescence analysis. The presence of severe nuclear damage, revealed cells progressing towards abnormal genotypes, due to a series of aberrant mitosis followed by unequal distribution of chromosomal content. The nuclear atypia (NA) more frequently observed were: a) micronuclei (MN); b) nuclear buds or blebs (NBUDs); c) notched nuclei; d) lobed nuclei; e) nuclei with nucleoplasmic bridge (NPBs); f) nuclei squashed, with a residual nuclear membrane; g) open nuclei, with membrane tape unrolled; and h) apoptotic bodies. Our results showed at medium-low doses a sustained genotoxic response, whose potency increased with the exposure time, becoming apparent as apoptosis induction, both by cell surface and nuclear changes. At the lowest doses, the longer was B[a]P exposure, greater was the involvement on masses of replicating cells, establishing the connection between the escape from apoptosis and the selection of tumoral cell evolution. In view of these results, there is no evidence of a threshold dose below which B[a]P was found not to be genotoxic in sea bream cultured hepatocytes. [ABSTRACT FROM AUTHOR]

This work presents an advanced version of a previous computer vision system that is appropriate for analyzing more complex fish behavioral traits. The system is capable of long-term recording of fish escape and bite behavior in tanks with excellent sampling accuracy and a minimum number of frames lost. In addition, the system is able to simultaneously record from nine different tanks with nine respective cameras, thereby allowing for specific experimental designs for statistical purposes. The evaluation of the system's operation and capabilities is achieved under specific biological activities in laboratory experimental conditions, with the activities duration similar to the system time characteristics. A sub-second analysis resulted in a detailed description of the escape and bite patterns of sea bream and bass in discrete steps, according to the video sequences. In general, the system was found to be able to assist in performing the behavioral studies of farmed fish. The final cost-effective system is characterized by long recording periods of high sampling accuracy, multiple digital camera acquisitions with high image quality, and state-of-the-art consistency. [ABSTRACT FROM AUTHOR]

The production of high quality juveniles at hatchery stages is important to ensure high growth potential during the on-growing phase. In the present paper, molecular growth markers of muscle development and growth in gilthead sea bream were validated in developmental stages/sizes that exhibit high accelerated growth rate, and rearing practices that are characterized by considerable size disparity. In gilthead sea bream the skeletal myosin light chain 2 (MLC2) is a structural molecule of the muscle that exists in two isoforms, A and B, which are known to mark hyperplasia and hypertrophy, respectively. The expression levels of the two isoforms and the robustness of its correlation with length growth were validated in a) larvae and juveniles of gilthead sea bream originating from the same broodstock and raised under intensive vs semi-intensive conditions, and b) in juvenile gilthead sea bream reared under commercial aquaculture practices and subjected to size grading with sorters of increasing diameter. A replacement of MLC2A by MLC2B was observed at metamorphosis in agreement with previous results. Larvae reared at the semi-intensive system outperformed in length growth and MLC2 expression those reared intensively and an earlier and faster replacement of MLC2A by MLC2B was observed at metamorphosis. Similarly, the ratio of MLC2A/MLC2B expression exhibited a tight, significantly negative correlation to total length of juveniles, independent of age. Overall, comparison of groups of gilthead sea bream of different origin rose under different conditions and of different developmental stages (larvae vs juveniles) provided significant evidence for the robustness of MLC2 expression as a growth marker. [ABSTRACT FROM AUTHOR]

Abstract: A 12-week feeding trial was conducted to determine dietary valine requirement of juvenile red sea bream (Pagrus major). Six isonitrogenous (45% crude protein) and isocaloric (4.38kcalg−1 gross energy) semi-purified diets were formulated with graded levels of valine (0.27, 0.79, 1.22, 1.69, 2.04 and 2.38% dry diet). Triplicate groups of fish (32.04±0.2g) were fed one of the diets to apparent satiation twice daily. At the end of the feeding trial, significantly (P <0.05) higher growth performance and feed utilization were obtained at dietary valine levels of ≥0.79% compared to fish fed 0.27% valine. Significantly lower whole-body moisture and higher protein contents were recorded at over 0.79% valine level and lipid content increased in fish fed 2.04% valine. Non-specific immune responses of fish were significantly improved by increment of dietary valine up to 2.04%. Plasma total protein, aspartate aminotransferase and total cholesterol levels were significantly affected by valine levels. Significantly lower postprandial ammonia excretion levels were obtained in fish fed dietary valine levels of 1.69 and 2.04% compared to the fish offered 0.27% valine. The optimum dietary valine requirement level was estimated at approximately 0.9% of dry diet (2% of dietary protein) by a broken-line regression analysis on the basis of weight gain and protein deposition. [Copyright &y& Elsevier]

Abstract: To investigate the physiological roles of arginine vasotocin (AVT) and isotocin (IT) in osmoregulatory process in gilthead sea bream (Sparus aurata), a time course study (0, 12h, and 1, 3, 7 and 14days) has been performed in specimens submitted to hypoosmotic (from 40‰ salinity to 5‰ salinity) or hyperosmotic (from 40‰ salinity to 55‰ salinity) challenges. Plasma and liver osmoregulatory and metabolic parameters, as well as AVT and IT pituitary contents were determined concomitantly with hypothalamic pro-vasotocin (pro-VT) and pro-isotocin (pro-IT) mRNA expression levels. Previously, sequences coding for pro-VT and pro-IT cDNAs were cloned. Two osmoregulatory periods related to plasma osmolality and metabolic parameter variations could be distinguished: i) an adaptative period, from 12h to 3days after transfer, and ii) a chronic regulatory period, starting at day 3 after transfer. Higher values in hypothalamic pro-VT and pro-IT mRNA expression as well as in pituitary AVT and IT storage levels in both hypo- and/or hyper-osmotic transfers have been distinguished. These increase correlated with changes in plasma cortisol levels, suggesting an interaction between this hormone and pro-VT expression. Furthermore, pro-IT expression enhancement also suggests a role of the isotocinergic system as a modulator in the acute stress response induced by hyper-osmotic challenge in S. aurata. [Copyright &y& Elsevier]

Abstract: The aim of this study was to evaluate a rapid, low-cost and easy-to-use system of impedance spectroscopy with two different electrodes (double electrode (DE) and arrowhead (AH)) to distinguish between fresh and frozen-thawed sea bream. Samples of fresh sea bream and those submitted to freezing at −18°C and to 2 freezing cycles, kept in frozen storage for different periods of time, were evaluated. The freezing process did not affect moisture, pH, TVB-N, or the microbial quality. However, it provoked a slight degradation of IMP, a slight increase in the TBA index and a decrease of the WHC and several textural parameters. All these changes were detected with the impedance spectroscopy using the DE, which could differentiate fresh sea bream from frozen-thawed samples. However, the AH could not discriminate between the different types of samples. The frozen storage time (15, 30 or 60days) did not have any effect on the microbial and physico-chemical parameters evaluated, or on the electrical properties of the muscle. Industrial relevance: To prevent unfair competition by false labelling, differentiating between fresh fish or that which has previously been frozen is an important issue of authenticity in the seafood sector. The use of impedance spectroscopy could provide a new approach to the development of small and portable instruments for frozen-thawed fish detection. Impedance spectroscopy could be a promising method for industrial use, authorities and quality control. The present work evaluates a rapid, low cost and easy-to-use system, based on impedance spectroscopy in order to differentiate between fresh and frozen-thawed sea bream. This method could be applied during any stage of fish marketing, facilitating quality control activities and the detection of fraud in the fish sector. [Copyright &y& Elsevier]

Abstract: A new optoelectronic nose for the shelf-life assessment of fresh sea bream in cold storage has been developed. The chromogenic array used eight sensing materials (based on aluminium oxide and silica gel) containing pH indicators, Lewis acids and an oxidation–reduction indicator. The colour changes of the sensor array were characteristic of sea bream spoilage. Colour modulations were measured on day 0 and for the samples held in cold storage for 2, 4, 7, 9 and 11days. Determination of moisture content, pH, total volatile basic nitrogen (TVB-N), drip loss, ATP-related compounds and K 1-value and microbial (mesophilic bacteria and Enterobacteriaceae) analyses were carried out on the same days. The changes in the chromogenic arrays data were processed by statistical analysis (PCA). Moreover, PLS statistical studies allowed the creation of models to correlate the chromogenic data with concentrations of mesophilic and Enterobacteriaceae. The results suggest the feasibility of this system to help develop optoelectronic noses for fish freshness monitoring. [Copyright &y& Elsevier]

Abstract: Fish growth models may help understanding the influence of environmental, physiological and husbandry factors on fish production, providing crucial information to maximize the growth rates of cultivated species. The main objectives of this work were to: i) develop and implement an Individual Based Model using a Dynamic Energy Budget (IBM-DEB) approach to simulate the growth of two commercially important Sparidae species in semi-intensive earth ponds, the white seabream which is considered as a potential candidate for Mediterranean aquaculture and the gilthead seabream that has been cultivated since the early 80s; ii) evaluate which model parameters are more likely to affect fish performance, and iii) investigate which parameters might account for growth differences between the cultivated species. The model may be run in two modes: the “state variable” mode, in which an average fish is simulated with a particular parameter set and the “Individual Based Model” (IBM) mode that simulates a population of n fishes, each with its specific parameter set assigned randomly. The IBM mode has the advantage of allowing a quick model calibration and an evaluation of the parameter sets that produce the best fit between predicted and observed fish growth. Results revealed that the model reproduces reasonably well the growth of the two seabreams. Fish performance was mainly affected by parameters related to feed ingestion/assimilation and reserves utilization, suggesting that special attention should be taken in the estimation of these parameters when applying the model to other species. Comparing the DEB parameters set of the two sparids it seems that the white seabream''s low growth rates are a result of higher maintenance costs and a lower feed assimilation efficiency. Hence, the development of new feed formulations may be crucial for the success of white seabream production in semi-intensive earth ponds. [Copyright &y& Elsevier]

Abstract: The present work aims to study the effect of a soluble non-starch polysaccharide (NSP), guar gum on white sea bream intestinal health through oxidative status and distal intestine morphology evaluation. A control diet was formulated to contain 40% crude protein, 14% crude lipids and 35% pregelatinized maize starch. Three other diets were formulated to include the same levels of all ingredients as control diet except for guar gum, which was included at 4% (diet GG4), 8% (diet GG8) or 12% (diet GG12). Compared to the control, lower catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) activities and higher SOD, glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities were observed in the whole intestine of fish fed with diets GG4 and GG12, respectively. Thiobarbituric acid-reacting substances (TBARS) levels were unaffected by diet composition. No morphological alterations in the distal intestine were found among groups. Overall, data on key enzymes of the antioxidant enzymatic defense mechanism suggested that diet-induced reactive oxygen species (ROS) generation is dependent on guar gum inclusion levels and low dietary inclusion of soluble NSP (up to 4%) may have a gut oxidation stress prevention effect. [Copyright &y& Elsevier]

Abstract: A trial was undertaken to estimate the protein requirement of sharpsnout sea bream (Diplodus puntazzo) and the protein sparing of dietary lipids. Ten diets were formulated to contain 5 protein levels (ranging from 15 to 55%) and two lipid levels (12 and 18%). Each diet was assigned to duplicate groups of 15 fish with a mean individual body weight of 49.3g. A quadratic model was used to adjust weight gain and N retention (gkgABW−1 day−1) to dietary protein levels. Based on that model, optimum dietary protein requirement was estimated to be 42.9% for maximum weight gain and 43.8% for maximum N retention, corresponding to a protein intake of 7.68gkgABW−1 day−1. Protein requirement for maintenance was estimated to be 0.71gkgABW−1 day−1. Dietary lipid level improved protein utilization efficiency but did not affect protein requirement. Whole-body protein content increased with dietary lipids and protein content, but no other relevant differences in body composition were noticed. Hepatosomatic index increased with dietary starch and lipid levels and was directly correlated to liver glycogen content. Diet composition affected plasma glucose clearance and cholesterolaemia but not plasma protein and triglyceride levels. [Copyright &y& Elsevier]

Abstract: Estrogen actions are mainly mediated by specific nuclear estrogen receptors (ERs), for which different genes and a diversity of transcript variants have been identified, mainly in mammals. In this study, we investigated the presence of ER splice variants in the teleost fish gilthead sea bream (Sparus auratus), by comparison with the genomic organization of the related species Takifugu rubripes. Two exon2-deleted ERα transcript variants were isolated from liver cDNA of estradiol-treated fish. The ΔE2 variant lacks ERα exon 2, generating a premature termination codon and a putative C-terminal truncated receptor, while the ΔE2,3* variant contains an in-frame deletion of exon 2 and part of exon 3 and codes for a putative ERα protein variant lacking most of the DNA-binding domain. Both variants were expressed at very low levels in several female and male sea bream tissues, and their expression was highly inducible in liver by estradiol-17β treatment with a strong positive correlation with the typical wild-type (wt) ERα response in this tissue. These findings identify novel estrogen responsive splice variants of fish ERα, and provide the basis for future studies to investigate possible modulation of wt-ER actions by splice variants. [Copyright &y& Elsevier]

In animals, biotransformation and the immune system interact with each other, however, knowledge of the toxic mechanism of benzo[a]pyrene (BaP) on these two systems is not well known. The present study investigated the toxic effects of BaP on the biotransformation system, cortisol level and DNA integrity of red sea bream (Pagrus major). The results showed that cortisol level was induced under the challenge of lipopolysaccharide (LPS). Short-term exposure (96 h) of BaP at environmental concentration significantly increased the cortisol level, hepatic EROD activity and CYP1A1 mRNA expression. When P. major was exposed to BaP for 14 d followed by LPS challenge this increased the cortisol level, EROD activity and hepatic DNA damage except CYP1A1 mRNA expression. Combined with our previous data, which showed that BaP exposure can modulate the immunologic response in P. major challenged with LPS, a hypothetical adverse outcome pathway of BaP on fish was suggested. [ABSTRACT FROM AUTHOR]

Global change is impacting aquatic ecosystems, with high risks for food production. However, the molecular underpinnings of organismal tolerance to both ocean warming and acidification are largely unknown. Here we tested the effect of warming and acidification in a 42-day experiment on a commercial temperate fish, the gilt-head seabream Sparus aurata . Juvenile fish were exposed to control (C 18 °C pH 8), ocean warming (OW 22 °C pH 8), ocean acidification (OA 18 °C pH 7.5) and ocean warming and acidification (OWA 22 °C pH 7.5). Proxies of fitness (mortality; condition index) and muscle proteome changes were assessed; bioinformatics tools (Cytoscape, STRAP, STRING) were used for functional analyses. While there was no mortality in fish under OW, fish exposed to OA and both OWA showed 17% and 50% mortality, respectively. Condition index remained constant in all treatments. OW alone induced small proteome adjustments (up-regulation of 2 proteins) related to epigenetic gene regulation and cytoskeletal remodeling. OA and both OWA induced greater proteome changes (12 and 8 regulated proteins, respectively) when compared to OW alone, suggesting that pH is central to proteome modulation. OA exposure led to increased glycogen degradation, glycolysis, lipid metabolism, anion homeostasis, cytoskeletal remodeling, immune processes and redox based signaling while decreasing ADP metabolic process. OWA led to increased lipid metabolism, glycogen degradation, glycolysis, cytoskeleton remodeling and decreased muscle filament sliding and intermediate filament organization. Moreover, as rates of change in temperature and acidification depend on region we tested as proof of concept an (i) acidification effect in a hot ocean (22 °C pH 8 vs 22 °C pH 7.5) which led to the regulation of 7 proteins, the novelty being in a boost of anaerobic metabolism and impairment of proteasomal degradation; and (ii) warming effect in an acidified ocean (18 °C pH 7.5 vs 22 °C pH 7.5) which led to the regulation of 5 proteins, with an emphasis on anaerobic metabolism and transcriptional regulation. The negative synergistic effects of ocean warming and acidification on fish survival coupled to the mobilization of storage compounds, enhancement in anaerobic pathways and impaired proteasomal degradation could pose a serious threat to the viability of sea bream populations. [ABSTRACT FROM AUTHOR]

In the present study we investigate the dietary administration effects of uridine monophosphate (UMP) to enhance the growth, hematological profile, innate and adaptive immune functions and stress resistance of juvenile red sea bream, Pagrus major . A casein fishmeal based semi-purified basal diet supplemented with 0% (control), 0.1% (UMP-0.1), 0.2% (UMP-0.2), 0.4% (UMP-0.4) and 0.8% (UMP-0.8) purified UMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 2.9 g) for 56 days. In general dietary UMP supplementation tended to improve growth performances (final body weight, % weight gain and specific growth rate), in which significantly higher performances were found in diet group UMP-0.4 followed by diet groups UMP-0.8, UMP-0.1 and UMP-0.2. UMP supplementation resulted increased feed conversion efficiency and protein efficiency ratio and significantly higher value (P < 0.05) obtained in diet groups UMP-0.4 and UMP-0.8. Feed intake also increased numerically (P > 0.05) with dietary UMP supplementation. Fish in control group without UMP supplementation showed significantly lower growth and feed utilization performances. The capabilities of enhancing immune responses of fish fed UMP supplemented diets were detected by nonspecific and acquired immune parameters measured in this study. Peroxidase activity (PA) was significantly higher in fish fed diet group UMP-0.8 and higher (P < 0.05) total serum protein (TSP) values obtained in diet groups UMP-0.4 and UMP-0.8. Fish fed diets with UMP supplementation had an increase adaptive humoral immune response (antibody titer) after 15 and 21 days of vaccination of formalin killed Vibrio anguillarum . In the 15th day after vaccination, significantly higher agglutination antibody titer was found in diet group UMP-0.4 and simultaneously other supplemented diet groups showed intermediate values. In terms of oxidative stress, diet group UMP-0.4 showed best condition with low oxidative stress and high antioxidant levels. Moreover, the fish fed UMP supplemented diets had better improvement (P < 0.05) in body lipid contents, hepatosomatic index, glucose and hematocrit content than the control group. Considering the calculated UMP content of the basal and other experimental diets, the quadratic regression analysis of weight gain and agglutination antibody titer revealed that the optimal levels of dietary UMP were 0.48 and 0.59%, respectively, for juvenile red sea bream, which is also in line with the most of the growth and health performance parameters of the fish. [ABSTRACT FROM AUTHOR]

In this study, we isolated and characterized programmed cell death10 (PDCD10), which is known to be related to apoptosis, from rock bream ( Oplegnathus fasciatus ). The full-length rock bream PDCD10 (RbPDCD10) cDNA (1459 bp) contains an open reading frame of 633 bp that encodes 210 amino acids. Furthermore, multiple alignments revealed that the six of the α-helix bundles were well conserved among the other PDCD10 sequences tested. RbPDCD10 was significantly expressed in the liver, RBC (red blood cell), gill, intestine, trunk kidney and spleen. RbPDCD10 gene expression was also examined in several tissues, including the kidney, spleen, liver, and gill, under bacterial and viral challenges. Generally, all of the examined tissues from the fish that were infected with Edwardsiella tarda and the red sea bream iridovirus (RSIV) exhibited significant up-regulations of RbPDCD10 expression compared to the controls. However, RbPDCD10 expression exhibited dramatic down-regulations in all of the examined tissues following injections of Streptococcus iniae , which is major bacterial pathogen that is responsible for mass mortality in rock bream. Our results revealed that rock bream PDCD10 may be involved in the apoptotic regulation of rock bream immune responses. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the dietary threonine (Thr) requirement of juvenile blunt snout bream and to assess the effects of Thr on the growth performance, feed utilization, whole body composition, plasma composition and target of rapamycin (TOR) pathway gene expression. Five isonitrogenous and isoenergetic semi-purified diets (34% crude protein) were formulated to contain graded levels of dietary Thr (0.58, 1.08, 1.58, 2.08 and 2.58% in dry matter (DM)). l -Amino acid mixture was supplemented to simulate the whole body amino acid pattern of fish, except for Thr. Triplicate groups of juvenHabte-Michael Habte-Tsionile fish (initial weight, 3.01 ± 0.01 g) were fed with the respective diet to near satiation four times daily for 9 weeks. The results indicated that final body weight, weight gain rate (WGR), specific growth rate (SGR), feed efficiency ratio (FER), protein efficiency ratio (PER), protein retention value (PRV), Fulton condition factor ( K factor), and whole body protein content significantly ( P < 0.05) increased with increasing dietary Thr levels up to 1.58% and thereafter decreased. Plasma free Thr concentration and total protein content rose as dietary Thr levels increased ( P < 0.05). High dietary Thr level (2.58%) triggered plasma urea content ( P < 0.05). Dietary Thr regulated TOR and eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2) gene expressions in the proximal-intestine (PI), mid-intestine (MI) and distal-intestine (DI) of juvenile blunt snout bream, which may explain further that dietary Thr enhanced growth performance and protein retention. Based on the second-degree polynomial regression analysis of SGR against dietary Thr levels, the optimum dietary Thr level for juvenile blunt snout bream was estimated to be 1.57% of the diet, corresponding to 4.62% of dietary protein. [ABSTRACT FROM AUTHOR]

A commercial diet (C) (48% protein and 20% lipids) and a high-digestible carbohydrate diet (CH) (37% protein, 12.5% lipids and 40% high-digestible carbohydrates) were used to feed sea bream juveniles for an 8-week period. In the commercial diet, more than 60% of ingredients were of plant origin from various sources, whereas the only component of plant origin in the CH diet was wheat. To determine the best time to administer carbohydrates and the possible protein-sparing effect, three different dietary regimes were established: C, CH-M and CH-A, and the corresponding diet was fed to sea bream in the morning (1.6% of bw) and in the afternoon (1% of bw), calculating quantities according to the amount of feed that fish ate during the acclimatization period. After the growth trial, specific growth rate (SGR), relative intestinal length, intestinal pH content, gastric and pancreatic digestive enzyme activities and nutrient absorption capacities were studied 5 h post-feeding after each meal (morning and afternoon). The acid protease activity measured was anticipatory and was higher when the next meal would have more protein. No differences in relative intestinal length or feed buffering capacity were found. The smaller ration given to sea bream in the afternoon led to a lower pancreatic release of alkaline protease and α-amylase and an up-regulation of D-Glc and L-Ala absorption capacity. A higher transit rate was measured when sea bream were fed the CH diet. When high-digestible carbohydrates were administered in the morning and the commercial diet in the afternoon, we observed a better assimilation of both diets due to compensatory mechanisms such as an increase in L-Lys, D-Glc and L-Ala absorption capacity after the morning feed, and a higher pancreatic release of alkaline protease and amylase after the afternoon feed. In contrast, when high-digestible carbohydrates were given in the afternoon, only a significant up-regulation of the capacity to absorb L-Lys was detected. Thus, the inclusion of high-digestible carbohydrates in the diet improved digestion and absorption processes when administered in the morning, leading to a protein-sparing effect that yielded growth comparable to that of fish fed an exclusively commercial diet. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the use of a rapid portable system based on impedance spectroscopy to assess fish freshness has been tested. The evolution of different physical and chemical parameters (moisture, fat, pH and TVBN) and impedance measurements (modulus and phase at different frequencies) of six different batches of sea bream (Sparus aurata) were analysed. Impedance spectroscopy was able to classify raw matter into six groups according to composition differences, and also to classify those samples stored for a time of between 0 and 15 days into different groups according to degree of freshness. TVB-N is one of the most usual parameters to assess shelf life periods of fish samples; the coefficient of determination (R 2) of 0.72 obtained in the Partial Least Squares regression for this parameter confirmed the potential application of the impedance spectroscopy for predicting sea bream freshness. [Copyright &y& Elsevier]

Abstract: Characterization of the major classes of digestive enzymes (amylase, protease and lipase) in the pyloric caeca and intestine of an omnivorous, white seabream (Diplodus sargus) and a carnivorous, meagre (Argyrosomus regius) fish species was assessed in response to dietary brewer's spent yeast (BSY, Saccharomyces pastorianus) supplementation. For that purpose, three isonitrogenous (50%) and isolipidic (12%) diets were formulated: unsupplemented (control) or supplemented with BSY at 1 or 2%. White seabream exhibited lower proteolytic but higher amylase and lipase activities than meagre. In white seabream, BSY administration enhanced amylase and protease activities in the pyloric caeca and the intestine and lipase activity in the pyloric caeca, while in meagre, improvement on amylase activity in the pyloric caeca was observed with the 2% BSY diet. The results of the current study indicate that white seabream has higher ability to digest non-protein energy sources than meagre and that diet supplementation with BSY improved digestive capacities in both species. [Copyright &y& Elsevier]

Abstract: In this study, diets containing 5, 10, 15, and 20% Gracilaria lemaneiformis (GL) (D1–D4 diet) were prepared to investigate the effects of GL on growth performance, carcass composition, activities of digestive enzymes, transaminases activities of black sea bream (Acanthopagrus schlegelii) juvenile. Weight Gain (WG) and Feed Efficiency Ratio (FER) of the fish fed D4 diet were significantly lower than that of control group. Fish fed with the D4 diet showed significantly lower crude lipid of both body and liver and Hepato-Somatic Index (HSI) than those fed with the control diet. Activities of pepsin in the stomach, lipase and amylase in the anterior intestine were significantly suppressed in fish which were fed with the D4 diet (P <0.05). On the other hand, the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly higher in fish which were fed with the D4 diet (P <0.05) than that of the control group. These results indicate that incorporation of the GL in the diet at up to 15% level for juvenile black sea bream is feasible in terms of the growth performance and the physiological state. [Copyright &y& Elsevier]

The ability to survive of two pathogens (Vibrio parahaemolyticus and Aeromonas hydrophila) spread over sea bream fillets packaged under different modified atmospheres (MAPs) was studied at 0°C and 4°C under refrigerated storage. The atmospheres used were 60% CO2/40% N2, 70% CO2/30% N2 and 80% CO2/20% N2 and a control batch packaged in air. Head space gas analyses, microbial counts and confirming test of pathogenic bacteria were carried out during 16days. The results obtained showed that all the modified atmospheres studied were effective to reduce the microbial load of sea bream fillets when compared with air packaged samples although small differences were found among MAPs. Temperature storage was the main factor to reduce microbial growth. V. parahaemolyticus was unable to grow at both temperatures, 0°C and 4°C (except air batches) while A. hydrophila showed significant growth at 4°C and microbial inactivation at 0°C. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to evaluate the effect of sodium alginate obtained from brown seaweed as a prebiotic supplement to the feed of reared sea bream (Sparus aurata). Addition of the alginate to a control diet was investigated at both concentrations 2% and 5%. Proximate composition in the flesh were not modified significantly by sodium alginate inclusion in the diet of the sea bream; however the fat and ash content in the specimens supplemented with 5% alginate were found to be significantly higher than those found in individuals who were fed the control diet. No significant differences in mineral content, fatty acid profiles, cholesterol content, texture parameters and sensory acceptability among the three studied groups. Results obtained in this study offer support for the use of alginate as a feed additive in sea bream diets since no significant effects were found in the flesh quality and characteristics of commercial size sea bream. [Copyright &y& Elsevier]

Abstract: A 60-day feeding experiment was carried out to investigate the effects of including lupin protein concentrate (LPC) and pea protein concentrate (PPC) in multiple essential amino acid-supplemented extruded diets for black sea bream (Acanthopagrus schlegeli). Nine diets, including eight diets formulated to contain four mixtures of LPC and PPC (L/P ratio, 3:0, 2:1, 1:2 and 0:3) with two dietary inclusion levels (300 or 500g plant proteinkg−1 dietary protein) and one diet with high-quality fish meal as the sole protein source (FM diet) were fed to 18 tanks of 13-g black sea bream. Growth performance, nutrient utilization, and brush-border membrane bound maltase activities were evaluated. An average weight gain (WG) of 32.7gfish−1 and an average feed conversion ratio (FCR) of 1.13g ingested dry matter (g gain)−1 were obtained. Neither plant protein inclusion level nor L/P ratio significantly affected body composition (except ash), fish somatic indices or plasma parameters. The high inclusion of 500gkg−1 resulted in significantly higher FCR than what was obtained with 300gkg−1 inclusion. The WG, whole body ash content, and nitrogen (N) and energy retentions of these fish were, however, significantly lower than that of the fish fed diets with low plant protein inclusion (300gkg−1). The highest LPC inclusion (L/P ratio=3:0) resulted in significantly higher feed intake and FCR, and lower N retention than the treatments with less LPC, but did not affect the growth rates or energy retentions. The diet with the highest PPC inclusion resulted in significantly reduced maltase activity in distal intestine. Any combination of LPC and PPC in essential amino acid-supplemented extruded diets, accounting for up to half of dietary protein, can be used without impairing fish growth. At high inclusion, combinations with more PPC are preferred, due to less efficient feed conversion caused by the LPC. [Copyright &y& Elsevier]

Abstract Artificial reefs are deployed in coastal systems to meet a range of social objectives and infrastructure requirements, such as recreational diving and fisheries enhancement. Such reefs are typically deployed on soft sediments and yet we know little of their effect on the biophysical characteristics of the surrounding benthos. This study investigated the composition of benthic infauna, sediment characteristics, and demersal fish foraging activity surrounding a large, steel, designed offshore artificial reef (OAR), measuring 12 m × 16 m x 12 m (height x length x width) and weighing approximately 42 tonnes. Using a gradient approach we established four transects with sediment sampling sites located 15, 30, 60, 120 and 240 m from the OAR. Taxon richness of infauna was lower close to the OAR (15, 30 m), and abundances of total infauna elevated at 15 m, driven largely by two families of polychaete (Onuphidae and Spionidae). Sediment characteristics (grain size, total organic carbon, metals) did not vary with distance from the OAR. Using unbaited videos we established that fish foraging activity on the soft sediments was enhanced close to the OAR (15 m), with a 5–10 fold increase in total foraging time that was largely accounted for by the activity of four benthivorous fish species (blue morwong Nemadactylus douglasii , the silver trevally Pseudocaranx georgianus , and goatfishes Upeneichthys vlamingii and U. lineatus). Fish foraging may cause changes in the composition of benthic infauna due to disturbance and selective predation. The effective benthic 'ecological halo' or 'footprint' of the OAR was 15 times the area of the actual reef. We demonstrate that a single large OAR can influence the surrounding benthic invertebrate and vertebrate communities, but that the effects are highly localised. Highlights • Foraging by demersal fish enhanced over soft sediments within 15 m of a large steel offshore artificial reef. • Ecological halo of an artificial reef approximately 15 times the area of the actual reef. • Reduced taxon richness, but enhanced abundance of invertebrates within 15 m of an artificial reef. • Disturbance and selective predation by demersal fish a potential driver of infaunal assemblages in soft sediments. [ABSTRACT FROM AUTHOR]

Close-kin mark-recapture (CKMR) data can be used on their own to provide estimates of fish spawning stock biomass, adult mortality rate and fecundity-at-age. However, CKMR data can also be integrated directly into a stock assessment. We present a simplified example of integrating CKMR data within the Stock Synthesis assessment framework, and use simulation to evaluate management strategies based on the harvest control rule used to set catch limits for fish stocks off southeast Australia. The simulations are tailored to jackass morwong, Nemadactylus macropterus, a moderately-long lived (up to 46 years) fish species that is believed to have exhibited a regime-shift reduction in recruitment. We identify the sample sizes needed for a CKMR-based management strategy to achieve similar performance to an (optimistically parameterized) catch-per-unit-effort (CPUE)-based approach for this species. A CKMR-based management strategy can perform at least as well as a CPUE-based approach and CKMR data provide information to better estimate parameters such as adult natural mortality. Moreover, CKMR-based management strategies are not subject to the risk associated with CPUE-based approaches related to trends in catchability. The performances of CKMR-based assessment methods and management strategies are likely case-specific, but this paper shows the viability of including CKMR data in next generation stock assessments and harvest control rules. [ABSTRACT FROM AUTHOR]

Sensory characteristics have been proven to be the strongest driver of fish consumption in general, as well as one of the main barriers for the complete acceptance of fish from aquaculture. The main goal of the present study was to determine consumers' liking for both farmed and wild fish and to evaluate the effect of information regarding the species and the method of production (wild capture/aquaculture) on it. Two groups of approximately 300 participants each consuming fish at least twice a week with similar socio-demographic distributions were recruited in three Spanish regions. Four different species (black spot sea bream, gilthead sea bream, sea bass and turbot), each of them from both wild capture fisheries and aquaculture, were evaluated by the two groups of participants. Within each species samples were obtained simultaneously and were frozen until their evaluation for a maximum of 1 month. One group of individuals evaluated the fish samples in a blind condition and the other in an informed condition. A significant effect of species was detected in both cases, although similar liking profiles were observed in the informed and blind conditions. The mean liking scores of sea bass, turbot and gilthead sea bream did not differ, and these species were significantly more appreciated than black spot sea bream. Information provided to consumers had a significant effect on hedonic evaluation of the fish samples. Therefore, in the informed condition, participants preferred wild fish but, interestingly, when information was not provided to them, the scenario was the opposite. It is worth mentioning that farmed fish was similarly evaluated in both the informed and blind conditions, whereas the liking of wild fish significantly increased when information was provided to consumers. These results seem to indicate that farmed fish per se does not have a negative image among consumers but also indicate the existence of a generalised positive attitude towards wild fish. A significant influence of consumer beliefs about farmed versus wild fish was observed in the informed condition. These findings constitute a valuable insight and provide an optimistic scenario for the aquaculture sector given that the improvement of the sensory characteristics of farmed fish does not seem to be necessary. However, providing consumers with reliable information that helps them to value the two types of fish based on scientific evidences would be needed. Statement of relevance The farmed fish sensory quality does not need to be improved. [ABSTRACT FROM AUTHOR]

Cysteine sulfinic acid decarboxylase catalyzes reaction of decarboxylation of cysteine sulfinic acid into hypotaurine. This step is considered as a rate limiting step of taurine biosynthesis in animals. Because of lower CD activity, marine fish has limited ability of de novo taurine synthesis and requires taurine in food. However, if we can develop a method to control CSD activity in marine fish, supplement of taurine to diet of marine fish is not necessary. In order to develop this technique, we have to isolate CSD from marine fish. This study, thereby, is conducted to isolate CSD from red sea bream Pagrus major and yellowtail Seriola quinqueradiata . We also analyze the expression of CSD in red sea bream, yellowtail, Japanese seabass Lateolabrax japonicus , and barfin flounder Verasper moseri . Total RNA was extracted from liver of red sea bream and yellowtail. Primers are designed against sequence of highly conserved region of reported CSD in other animals for RT-PCR. 776 bp and 725 bp partial CSD sequences were successfully cloned from red sea bream and yellowtail. By 5′ and 3′ RACE methods for cloned partial CSD sequences, total length of CSD (1882 bp and 1821 bp) from red sea bream and yellowtail was determined. Classification of deduced amino acid sequence revealed that red sea bream and yellowtail CSD showed 88.8% homology similar to Nile tilapia, platyfish, etc. Domain analysis shows that pyridoxine binding region was conserved in CSD from both species. Expression analysis of CSD from red sea bream, Japanese seabass, barfin flounder and yellowtail indicated that CSD is expressed in a variety of tissues but commonly in the liver and pyloric ceca of all species examined. Additionally, strong CSD expression was observed in the heart in all species examined except for Japanese seabass. [ABSTRACT FROM AUTHOR]

Information on the contribution of offshore oil and gas (O&G) platforms to fish productivity is required to contribute to the decision-making process to remove, partially remove, or retain these structures during decommissioning after petroleum production ceases. The present study assesses the biomass and fish production of one common and abundant fish species (Caesioperca lepidoptera – butterfly perch) and two commercially fished species (Helicolenus percoides – reef ocean perch; Nemadactylus macropterus – jackass morwong) on eight O&G platforms and in surrounding natural habitats in the Bass Strait, south-east Australia, where options for decommissioning are being assessed. High-definition stereo-video imagery was collected by remotely operated vehicle (ROV) from eight platform facilities, their immediate benthic surrounds, reference areas reflective of the likely pre-installation seabed state (sand-dominated) and a nearby natural 'reef' area referred to as south-east reef (some limestone foundation). The biomass of all three species was low in the benthic surrounds of platforms, at reference locations and at south-east reef where minimal cover by benthic organisms was recorded and, as such, there was little to no fish production for the three study species in these areas. We observed a total fish biomass of 2.85 tonnes across the eight platforms for the three fish species surveyed, with high variability across platforms. Total production (P) across all platforms was estimated at 1244 kg/year for the three species, with a mean fish production density of 82 g/m2/year. Approximately 79% of total production is considered 'new' production (984 kg/year i.e., the production attributed to the presence of the platforms; with a mean production density of 64 g/m2/year). The remaining 21% could be retained or redistributed into the surrounding area if platforms were removed. C. lepidoptera accounted for the majority (90%) of biomass and of total production for all three species across all locations surveyed. Despite only accounting for a small proportion of platform surface area, the bottom 5 m sections of platforms had 41% of the total biomass observed and accounted for 46% of total production of these three study species. Production measures for platforms surveyed here are relatively high compared to other artificial reefs and habitats around the world. Total removal of these platforms will likely result in a reduction of fish biomass and fish productivity (incl. several fishery species) in the immediate vicinity. • Platforms promote fish diversity and abundance in areas where it would be otherwise be minimal. • Platform production measures were relatively high compared to other artificial reefs and habitats around the world. • The bottom 5 m sections of platforms contained 41% of the total biomass observed and accounted for 46% of total production. • Complete removal of infrastructure would likely eliminate most fish production at that location. [ABSTRACT FROM AUTHOR]