Genetic assessment of three gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis> L.) populations along the Spanish coast and of three broodstocks managements

The gilthead sea bream (Sparus aurata L.) is one of the most important Sparid farmed in Europe, especially in the Mediterranean area. However, efficient breeding programs for this species are scarce and very little, and it is known concerning their population structure. The present study was mainly designed to genetically characterize, by microsatellite markers, three gilthead sea bream populations sampled along the Spanish coast (Cantabrian Sea, the Atlantic Ocean and Mediterranean Sea) and their progeny with the aim of studying its genetic variability and its genetic structure. Moreover, we evaluated different strategies of broodstocks management (breeders’ number, origin and sex combination) on parental contributions and on effective breeding numbers. That number of breeders in the stock was of great importance to the maximization of contribution since the larger broodstock resulted in larger proportion of parents contributing. Variation in dam and sire spawning incidence and in number of progeny produced per dam and per sire was translated into reduced effective breeding numbers and consequently into expected increased inbreeding rates. Our results highlight the high genetic variability of the studied sea bream populations, as well as the existence of three genetically differentiated populations along the Spanish coast. These findings should be relevant for the establishment of successful breeding programs in aquaculture of the gilthead sea bream.     

Predicting the growth of gilthead sea bream (Sparus aurata L.) farmed in marine cages under real production conditions using temperature- and time-dependent models

The growth of gilthead sea bream ( Sparus aurata ) has been studied considering five multiple exponential regression models using data from 20 lots of gilthead sea bream growing in 20 marine cages from a Mediterranean commercial fish farm. The final weight ( W _f) of fish was predicted in relation to the initial weight ( W _i), time ( n ) and temperature ( T ), or the sum of effective temperatures (∑ T _ef). The estimated weight results from the simulation using the five models have been compared with the real final weight values using the mean of the absolute values of the prediction errors in short and long term (the precision value). All models presented a high determination coefficient, above 96%, and good prediction values in the short term. Regression models were tested using data from six new cages. The best models for predicting the growth of sea bream long term were the ones where final weight is expressed in relation to the initial weight and the sum of effective temperature,     and     obtaining long-term prediction errors 12.9% and 10.7% respectively.     

Stock enhancement of gilthead sea bream (Sparus aurata, L.): assessment of season, fish size and place of release in SW Spanish coast

Gilthead sea bream, Sparus aurata L., is a highly level protein species in Mediterranean countries and can easily be produced in hatcheries. Despite the commercial interest in the species, alternatives to aquaculture such as ranching and stock enhancement, which have proven to be profitable for other species, have not been attempted for the gilthead sea bream. The aim of this paper is to evaluate the feasibility of these alternatives for the Atlantic coast of the southern Iberian Peninsula, where this species is highly valuable for professional and amateur fishermen. A total of 30 323 individuals marked with average weights of 15, 100, 316 and 854 g were released between 1993 and 1997 at six different locations. For each of these locations, the displacements, growths, the oldest recapture and the percentage of recapture were determined. The Bay of Cádiz turned out to be the most suitable location since the highest recapture (2.41%, S.E. 0.53) and specific growth rates (0.86, S.E. 0.09), as well as small displacements (8.16 km, S.E. 0.95), were found in this location. One hundred grams was the best size for enhancement as fish of 15 g showed very low recapture rates (0.12%, S.E. 0.08), while fish larger than 316 g made significant displacements (42.87 km, S.E. 4.73). Growth and displacement also point to summer versus spring, winter or fall as the best releasing period for stock enhancement of this species in the analysed area. These elements point to the feasibility of implementing a stocking program for gilthead sea bream. This must have the bay of Cádiz as the core place of interest, releasing 100-g fish in late summer.     

Effects of dietary mannan oligosaccharides in early weaning diets on growth,survival, fatty acid composition and gut morphology of gilthead sea bream (Sparus aurata,L.) larvae

Early weaning of marine fish larvae with dry diets delays gut maturation and reduces growth rates. In juvenile and adult forms of several marine fish species, inclusion of dietary mannan oligosaccharides (MOS) improves gut integrity and functionality, but the effects of MOS inclusion in gilthead sea bream (Sparus aurata, L.) larval diets have not been addressed yet. Thus, this study assesses the effects of dietary MOS inclusion on survival, growth performance, gut morphology, feed acceptance and quality of gilthead sea bream larvae. For that purpose, 16 days post‐hatched gilthead sea bream larvae were fed four graded levels of MOS (Biomos^®, Alltech, Nicholasville, KY, USA) in weaning diets as follows: 0 g kg^?1 MOS, 0.5 g kg^?1 MOS, 1.5 g kg^?1 MOS and 2 g kg^?1MOS. Dietary MOS did not affect feed acceptance in gilthead sea bream larvae (P > 0.05). MOS supplementation was correlated in a dose‐dependent way with higher larval survival (P = 0.026). After 15 days of feeding, dietary MOS increased whole larvae (P < 0.01) arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Gilthead sea bream larvae fed 2 g kg^?1 MOS presented higher gut occupation with goblet cells after feeding compared with larvae fed the other dietary treatments. Overall, the results suggest that inclusion of MOS in early weaning diets for gilthead sea bream improves essential fatty acid utilization and may promote growth and final survival.     

Observations on the increase of wild gilthead seabream,Sparus aurata abundance,in the eastern Adriatic Sea: problems and opportunities

The recent increase of the local population of gilthead seabream, Sparus aurata, in three areas along the southeastern Adriatic Sea: Malostonski Bay (Croatia and Bosnia and Herzegovina), Neretva Estuary (Croatia) and Boka Kotorska Bay (Montenegro) and its adverse effects on shellfish culture by preying on Mediterranean mussels, Mytilus galloprovincialis, and the European flat oyster, Ostrea edulis, are studied. The results from the analysis of the existing information show that the main reason for the recent increase is the escapes from local fish farm which enrich the local population constantly with new gilthead sea bream. The existence of practically endless food in the area of the shellfish farms allows the concentration of the population in the region instead of its dispersion along the Adriatic coast. Moreover, ecological analysis indicates that the gilthead seabream is facing a very low competition from other local species which enhances its capacity to further populate the region. While the impact on the ecosystem is not yet known, the socio-economic impact of the increase of the gilthead seabream population is evident today. Many shellfish farms are closing today in the region since the damages may reach over 90 % of the production.     

Physiological stress and innate immune response in gilthead sea bream (<Emphasis Type="Italic">Sparus aurata)</Emphasis> and sea bass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>) exposed to combination of trimethoprim and sulfamethoxazole (TMP-SMX)

The purpose of this study was to determine whether gilthead sea bream and sea bass treated with combination of trimethoprim and sulfamethoxazole (TMP-SMX) differed in terms of physiological and innate immune biomarkers. Fish were exposed to TMP-SMX at 40 ppm concentration for 1 h as a prophylactic usage. Plasma cortisol, glucose, electrolytes (Ca, P, Na, K, Cl, and Mg) as well as plasma lysozyme activity, C-reactive protein (CRP), and ceruloplasmin (Cp) were measured soon after treatment and following 24 and 48 h in normal sea water for recovery. Treatment with TMP-SMX in both gilthead sea bream and sea bass led to an increase in plasma cortisol and glucose. Fluctuations in some electrolytes were found after treatment and during recovery period, however, the ratios of monovalent ions in treated sea bream were similar to control. Hematocrit values as well as plasma lysozyme activity in gilthead sea bream and sea bass were not affected by the treatment. CRP in gilthead sea bream and Cp in sea bass responded to the treatment with decreased levels. Both gilthead sea bream and sea bass displayed a rapid physiological stress response and sensitivity to TMP-SMX exposure, which requires more than 48-h period for regaining homeostasis.     

Genetic comparison of wild and cultivated European populations of the gilthead sea bream (Sparus aurata)

This study represents the first large-scale population genetic analysis of the marine fish gilthead sea bream (Sparus aurata), one of the most significant species in the South European aquaculture. Six wild and five cultivated sample sets covering the South Atlantic and Mediterranean European area have been screened for allozyme, microsatellite and mitochondrial DNA (mtDNA) variation. Microsatellites showed higher levels of polymorphism than allozymes. The low variability of mtDNA offered no basis for population differentiation.

The results reveal levels of variability for S. aurata above those from other sparids. Cultivated populations show a slight decrease of variability related to the wild ones, but not sufficient to document inbreeding depression effects, thus suggesting a fairly proper management. Wild populations reveal a slight degree of differentiation more pronounced with microsatellites than with allozymes, but not apparently associated with geographic or oceanographic factors. The cultivated populations seem to be highly divergent as a result of genetic drift caused by different factors pertaining to their respective histories. With both markers, the two cultivated Spanish sample sets are the most divergent. The high differentiation between cultivated and wild populations from the same area might indicate no evidence for significant genetic flow between them.

This study provides an insight into the population structure of S. aurata, although more questions have arisen that need to be solved. This can be achieved by further screening of small-scaled targeted sample sets in the studied area.     

Influence of dietary levels of soybean meal on the performance and gut histology of gilthead sea bream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.)

The present study was performed to determine the effect of soybean meal (SBM) on the performance and gut histology of gilthead sea bream and European sea bass. Three isonitrogenous and isolipidic extruded diets (crude protein, 470 g kg⁻¹ diet; crude fat, 200 g kg⁻¹ diet) were formulated containing 0 (0 SBM), 180 (180 SBM) and 300 (300 SBM) g kg⁻¹ diet SBM and tested on both species in two separate experiments. Fish at an initial average weight of around 18 g were randomly allocated to 800 L square tanks connected to a closed recirculating system. The trials lasted 80 days for sea bream and 89 days for sea bass. Fish were hand-fed to apparent satiation. Increasing the level of SBM had no significant effects on the specific growth rate, feed intake and feed conversion rate in both the species. In the sea bream distal intestine, lamina propria was moderately and diffusely expanded in some fish due to an increase in cell infiltration represented by mononuclear cells, this finding being more frequent in animals fed diet 300 SBM. No other morphological alterations in intestinal folds, enterocytes or other inflammation signs were noticed in the sea bream distal intestine of any group. No histological differences were found in sea bass in any experimental group.     

Stress assessment,quality indicators and shelf life of three aquaculture important marine fish,in relation to harvest practices,water temperature and slaughter method

The objective of this study was to evaluate the effect of harvest practices and slaughter method on stress, quality and shelf life of whole fish (gilthead sea bream, European sea bass and red sea bream) towards the development of a humane slaughter practice. The use of hook and line resulted in significantly lower plasma cortisol and glucose in European sea bass and gilthead sea bream. Water temperature at harvest affected significantly the concentrations of stress indicators (plasma cortisol and glucose), mainly in European sea bass and gilthead sea bream. No significant differences were observed between the harvesting methods, regarding fish appearance, microbial spoilage and sensory scoring and subsequently shelf life. However, significantly lower hardness was recorded in fish harvested using the electric stunner, compared to the fish killed with slurry ice of the same harvesting period. Shelf life ranged between 13–18 days for gilthead seabream, 10–16 days for European sea bass and 10–14 days for red sea bream, depending on harvesting period.     

Preliminary Results on Rearing of Sparus Aurata × Pagrus Pagrus Hybrids. Performance Comparison With the Parental Species

Hybridization between gilthead sea bream, Sparus aurata, and red porgy, Pagrus pagrus, was undertaken and viable hybrids were produced by an artificial hormonal-induced cross. The hybrids, from the cross of female red porgy and male gilthead sea bream (Pp × Sa), survived through the yolk-sac larval stage. The hybrids produced from the cross of female gilthead sea bream and male red porgy (Sa × Pp) presented higher mortality in the larval stage (98.4%) compared to gilthead sea bream (80.0%) and red porgy (92.5%). Afterwards, the Sa × Pp hybrid was compared to the offspring of its parental species under the same rearing conditions (tanks of 500 l capacity, natural light, ambient temperature, self-feeding with commercial feed) in a 40–week experiment. In this comparative study, the Sa × Pp hybrid had intermediate mortality rate (6%), compared to gilthead sea bream (0%) and red porgy (21%). The growth profile of this hybrid resembled the slow growing phases of its parents (red porgy in warm period and gilthead sea bream in cold period). The feed conversion ratio between fish forms was not significantly different (1.54–1.84 in the Sa × Pp hybrid, 1.53–1.56 in the maternal species and 1.33–1.40 in the paternal one). The body weight variation in the Sa × Pp hybrid was quite high (31.7–37.9%), compared to that in gilthead sea bream (19.7–24.7%) and red porgy (18.0–31.3%). With respect to body coloration, the Sa × Pp hybrid was distinguishable and classified into groups of red porgy-like (55.1%), gilthead sea bream-like (40.6%), and intermediate forms (4.3%). The preliminary results of this study proved that the produced Sa × Pp hybrid had too low a performance for aquaculture use, but the interesting consequent hereditary potential could be a useful tool in fish hybridization practice.     

Optimum selenium levels in diets high in plant‐based feedstuffs for gilthead sea bream (Sparus aurata) fingerlings

Substitution of marine ingredients (FM‐FO) by plant protein and oil sources can modify selenium (Se) levels in feeds. Se plays an important role in the antioxidative defence by forming part of selenoproteins. Se requirements of gilthead sea bream are not accurately determined; therefore, this study was conducted to define Se supplementation levels in low FM‐FO practical diets for sea bream fingerlings. A plant‐based diet containing 0.45 mg Se/kg diet was used as the basal diet. Four other diets were supplemented to contain 0.68, 0.86, 1.00 or 1.70 mg Se/kg diet, supplied as sodium selenite. Sea bream, weighing 12.6 ± 1.4 g, were distributed in triplicate groups per diet and fed for 42 days. Se supplementation up to 1.00 mg Se/kg significantly improved the growth of sea bream, whereas further increase up to 1.70 mg Se/kg diet reduced growth. The results of this study suggest that the optimum dietary levels of sodium selenite in diets with low FM‐FO with basal levels of 0.45 mg Se/kg are around 0.94 mg Se/kg to promote growth of gilthead sea bream juveniles. On the contrary, dietary levels of 1.70 mg Se/kg were found to be excessive and caused growth reduction, increased catalase expression and hydropic degeneration in the liver.     

Acute Toxicity of Ammonia and Nitrite to Sea Bream,Sparus aurata (Linnaeus, 1758), in Relation to Salinity

Sea bream, Sparus aurata, is one of the most important fish species that is commonly cultured in the Mediterranean and the eastern coasts of the Atlantic Ocean. The life cycle of sea bream in its natural habitat passes through hyposaline and hypersaline lagoons. It is important to determine the tolerance of the fish to nitrogenous compounds for aquaculture at maximum stocking densities. In the present study, a series of acute experiments were performed to evaluate the effect of salinity on ammonia and nitrite toxicity to sea bream. The fish were exposed to different ammonia and nitrite concentrations according to the static renewal methodology at three different salinities (10, 20, and 30 ppt) and at a temperature of 20 C and a pH of 8.2. The toxic effect of total ammonia nitrogen (TAN) and nitrite nitrogen (NO₂‐N) decreased with increasing salinity levels (P < 0.001). Acute toxicity (96‐h lethal concentration 50 [LC₅₀]) values of TAN were determined to be 5.93, 11.72, and 19.38 mg/L at 10, 20, and 30 ppt salinity, respectively. The 96‐h LC₅₀ values of NO₂‐N were determined to be 370.80, 619.47, and 806.33 mg/L at 10, 20, and 30 ppt salinity, respectively. Results indicate that sea bream is less tolerant to ammonia but more tolerant to nitrite compared with some other fish species.     

Origin of broodstock and effects on the deformities of gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis> L. 1758) in a Mediterranean commercial hatchery

The use of broodstock of different origin as a method to improve fry production performance and consequently to minimize deformities was examined at industrial scale in a commercial gilthead sea bream hatchery. The outcome of fry production from three different broodstock groups (BA: broodfish (Mediterranean) with multiannual hatchery presence, BB: selected offspring originating from the BA group, and BC: broodfish of Atlantic origin) was investigated in the same rearing conditions and feeding protocol. Performance factors assessed were the survival and weaning of the larvae; the mortality rates from the “weaning until the end of the hatchery stage” of the larvae/fry; the percentage of fry without swim bladder; the percentage of fry with skeletal deformities and the feed conversion ratio. In all factors, no statistical differences among the experimental groups were detected. However, due to early rejection of the deformed individuals, benefits are expected from the decrease of the supplied amount of food and the reduced labor cost.     

Stocking of native Mediterranean brown trout (Salmo trutta) into French tributaries of Lake Geneva does not contribute to lake-migratory spawners

Abstract –  We studied the contribution of stocking with Mediterranean autochthonous brown trout ( Salmo trutta ) to the lake-migratory spawners in French tributaries of Lake Geneva. This singular lake system is inhabited by both the resident and the migratory life-history form, and by trout of Atlantic and Mediterranean origins. Using two discriminatory microsatellite loci between the Atlantic and Mediterranean alleles, we compared the genetic composition of the migratory Atlantic populations of the four main tributaries before (1999; N  = 113) and after (2004, 2005 and 2006; N  = 137) recent introductions of native Mediterranean trout. No significant modification of the genetic composition was detected in all four populations over time and only two individuals were statistically assigned to the Mediterranean strain by the Bayesian method implemented in the structure program. These results suggest a negligible contribution of the stockings with autochthonous Mediterranean trout to the lake-migratory spawners migrating into the four tributaries.     

Recent advances in European sea bass and gilthead sea bream nutrition

European sea bass (Dicentrarchus labrax) and gilthead sea bream(Sparus aurata) are amongst the most important finfish speciescultured in the Mediterranean region. Production of these species isnowadays a well-controlled process, but knowledge of their nutritionalrequirements is still very limited. Nevertheless, a considerable amountof data has been accumulated in recent years, and the purpose of thispaper is to review the recent advances on the nutritional requirementsof sea bass and sea bream. The optimum protein to energy ratio of thediets of sea bass and sea bream seem to be higher than for salmonids,and there is some evidence that high dietary lipid levels have nobeneficial effects on fish performances. Although the essential aminoacid requirements were estimated by the ideal protein method, data basedon the dose-response method is only available for a few amino acids.Essential fatty acid requirements were estimated for sea bream juvenilesbut data is lacking for sea bass. Vitamin and mineral requirements ofthese species are practically unknown. Although the importance ofbroodstock nutrition on gonadal development, spawning and egg quality isrecognized, few studies were done to elucidate these aspects. The recentdevelopment of microparticulate diets for larvae will contribute to theaccurate evaluation of their nutritional requirements.     

Inhibition of HPI axis response to stress in gilthead sea bream (Sparus aurata) with physiological plasma levels of cortisol

This study investigates the effect of corticosteroid (cortisol) administration on the stress response of the gilthead sea bream Sparus aurata subjected to a 48 h confinement. The effect of (in-vitro and in-vivo ) cortisol administration on the in-vitro ACTH sensitivity of the interrenal tissue; the plasma levels and tissue concentration of cortisol; and the plasma levels of ACTH, -MSH, -endorphin and glucose were determined. Confinement caused a transient and concomitant increase in plasma cortisol and ACTH levels. However, in cortisol-fed fish the plasma ACTH levels were lower, indicating a suppresion of the ACTH release from the corticotropes by cortisol. In contrast to the activation of the corticotropes, the levels of plasma melanotrope derived peptides were not affected. In spite of the fact that interrenal cells of cortisol-fed gilthead sea bream released less cortisol than controls, the interrenal sensitivity to ACTH was not affected by in-vivo and in-vitro cortisol administration. This suggests that the interrenal sensitivity to ACTH in stressed (confinement) sea bream is probably not regulated by -MSH, N-ac--END, or by cortisol. Thus, in gilthead sea bream the interrenal sensitivity to ACTH could be regulated at the hypothalamus and/or pituitary and communicated via circulating ACTH levels.     

Ontogeny of tolerance to and avoidance of ultraviolet radiation in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli

ABSTRACT:   Ontogenetic changes of tolerance to, and avoidance of, ultraviolet-B radiation (UV-B) were examined in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli . In the tolerance experiment, larvae and juveniles (age 13–46 days) were put in beakers, and were exposed to one of five different levels of UV-B radiation (1.8, 1.1, 0.2, 0.1, and 0 W/m²) for one hour. Their survival rates were calculated either 12 or 24 h later. In the avoidance experiment, fish (age 3–49 days) were put in a long experimental tank, half of which was covered with UV-blocking film and placed under two levels of UV-B radiation (1.1 and 0.2 W/m²), and their avoidance indices were calculated. Black sea bream had significantly better survival compared to red sea bream for most ages. Only black sea bream of ages 37 and 49 days showed significant avoidance of UV radiation under the higher level of UV-B, whereas both species did not show avoidance on any days at the lower level. The present results suggest that black sea bream are significantly better adapted to habitats with high UV-B radiation, than red sea bream, reflecting that back sea bream live in shallower waters through their early life stages.     

Effects of chronic confinement on physiological responses of juvenile gilthead sea bream, Sparus aurata L., to acute handling

Understanding how gilthead sea bream, Sparus aurata L., an important Mediterranean Sea species for aquaculture, respond physiologically to stressors commonly encountered in intensive rearing is important for effective production, as managing for stress is a major factor in maintaining healthy fish stocks. Our objective was to determine whether holding juvenile gilthead sea bream at a high density (HD), as a chronic stressor, would affect their physiological responses to a subsequent acute handling stressor. After acclimation at a low density (LD) of 6 kg m^?3 in 200‐L circular tanks containing 33–36 g L^?1 recirculating seawater at 19°C under a normal photoperiod, juvenile 37‐g gilthead sea bream were confined for 14 days at a HD of 26 kg m^?3 and then subjected to 30‐s aerial emersion in a dipnet. Plasma levels of cortisol, glucose, lactate, osmolality and chloride were determined in fish held in separate lots during LD (control) and HD confinement at 0, 1, 2, 7 and 14 days, and then after handling at 0, 1, 2, 4 and 8 h. Although plasma cortisol levels were similar in LD and HD fish groups after 14 d of confinement (15 and 23 ng mL^?1, respectively), the cortisol response in fish from the HD treatment at 1 and 2 h following acute handling (70 and 37 ng mL^?1, respectively) was only about half of that measured in the control group (139 and 102 ng mL^?1); plasma cortisol was similar in both groups by 4 and 8 h. In contrast, plasma glucose elevations in response to handling were higher at 4 and 8 h in the HD‐held fish (94 and 72 mg dL^?1, respectively) than in those from the LD treatment (59 and 51 mg dL^?1); glucose responses were similar in both groups at 1 and 2 h after handling and throughout confinement. Plasma lactate levels were higher in LD fish than in the HD group at the beginning of the experiment but were similar after 14 d confinement and responses to handling were similar (e.g. 33 and 35 mg dL^?1 at 1 h). Plasma osmolality showed increases during the first 2 h after acute handling but no differences were evident between the two density treatments at any time during confinement or posthandling. Plasma chloride levels did not change throughout the experiment. The reduced plasma cortisol response to acute handling likely resulted from negative feedback of mildly but chronically elevated circulating cortisol caused by the confinement stressor on the hypothalamic–pituitary–interrenal axis. While other post‐handling physiological changes also showed differences between treatment groups, the suppressed cortisol response in the HD‐held fish suggests a reduction in the gilthead sea bream's normal capacity to respond to an acute stressor.     

Effect of high-level fish meal replacement by plant proteins in gilthead sea bream (Sparus aurata) on growth and body/fillet quality traits

Juvenile gilthead sea bream (initial body weight ca. 100 g) were reared in an indoor flow through marine water system for 1 year. Fish were fed two isoenergetic [19.2 kJ g⁻¹ dry matter (DM)] and isoproteic (426 g kg⁻¹ DM) diets either based on fish meal (diet FM) or on a mixture of plant protein sources (diet PP), replacing 75% of fish meal protein. The growth trial was conducted in duplicate, two tanks for each dietary treatment. Growth performance and feed utilization were registered. Fillet quality parameters were evaluated and sensory analyses on cooked fillet were performed. Both groups had similar weight gain and specific growth rates. Feed intake was higher in sea bream fed diet FM (0.48 versus 0.44), while feed efficiency and protein efficiency ratio were significantly higher in sea bream fed PP (0.83 versus 0.77 and 2.0 versus 1.76, respectively). Sea bream fed diet FM had a lower hepatosomatic index (0.80 versus 0.87%), and a higher fillet yield (45.9 versus 44.9%). The fillet from sea bream fed diet FM had higher moisture (696 versus 682 g kg⁻¹), lower lipid levels (91 versus 100 g kg⁻¹) with higher levels of n‐3 polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA), while the PP fed sea bream presented a higher level of PUFA n‐6. There were minor differences in muscle free amino acid levels between the two diet groups. As regards sensory evaluation of cooked fillet, the judges were unable to discriminate the two dietary groups of fish. Summarizing, the results demonstrate the possibility to use diets containing high levels (750 g kg⁻¹) of plant ingredients in gilthead sea bream without affecting growth performance and with minor effects on quality traits of commercial size sea bream.