Sensory evaluation of farmed sharpsnout seabream (Diplodus puntazzo)

The first attempts at applying aquacultural techniques to sharpsnoutseabream (Diplodus puntazzo) have proved very promising.One of the factors to keep in mind when analysing the viability of a speciesforindustrial farming is that of consumer acceptance of the product, a variablethat can be measured by sensory evaluation tests. To that end, 107 participantsfrom a number of work centres were assessed with hedonic sensory tests usingsharpsnout seabream samples. For reference purposes, the tasting also includedgilthead seabream samples. Participants were asked to fill out a questionnairethat included questions concerning their preferences for any one fish. Weanalysed the sensory attributes of both fish species using a hedonic scale, andalso their acceptability (disposition to purchase) to consumers. The resultsproved fairly encouraging with a view to sharpsnout seabream large-scaleproduction. All attributes tested in the sensory profile analysis werepositively rated. About 60% of the surveyed population would consider buyingsharpsnout seabream at a price similar to that of gilthead seabream (10∈),and 85% found it to be pleasing to the eye. Aside from flavour, its texture,juiciness and fat level are the most important appraisal attributes. Efforts toimprove the organoleptic characteristics of the species should focus mainly onthese attributes.     

A study of the pattern of digestive enzymes in Diplodus puntazzo (Cetti, 1777) (Osteichthyes, Sparidae): evidence for the definition of nutritional protocols

The digestive enzymes (proteases, carbohydrases and lipases) present along the alimentary tract of juveniles and adults of Diplodus puntazzo were studied. The data obtained showed a different distribution of the enzymatic activities in the different parts of the alimentary tract. Levels of enzymatic activity in the adults were higher than those measured in juveniles, suggesting that adults have a greater ability to digest larger pieces of food. The enzymatic pattern of D. puntazzo justifies its omnivorous habit and suggests an high potential for digesting vegetable polysaccharides. The results of this study suggest the need to adapt the diet to the digestive potential of this new farming species, thus contributing to the attainment of a product that is qualitatively more similar to the wild one.     

Effect of feeding rate on fatty acid composition of sharpsnout seabream (Diplodus puntazzo)

The effects of different feeding rates on the lipids fatty acid profile of sharpsnout seabream (Diplodus puntazzo) tissues were studied. During a 15‐day period, four fish groups were allowed to feed to satiation, at two‐thirds and one‐third of satiety, and starved, respectively. Reducing food intake progressively increased the n‐3:n‐6 relationship by increase of n‐3 (mainly Highly Unsaturated Fatty Acids) and decrease of n‐6 fatty acid percentages. In perivisceral fat, this n‐3:n‐6 value was already statistically significant lower for the group fed to satiety (1.29 versus 1.71, 1.80 and 1.65 for the two‐third‐fed, one‐third‐fed and fasted groups, respectively), whereas in the white muscle (1.69 versus 2.13 and 2.12) and liver (0.83 versus 1.40 and 2.66) the differences were statistically significant only for the one‐third‐fed and fasted groups. Linoleic acid was the main contributor to the n‐6 drop, whereas the n‐3 fatty acids preferentially preserved were for the most part essential fatty acids. Fat quality indices (thrombogenic and atherogenic) were not affected by food restriction except for liver, being the former significantly lower in the one‐third‐fed and fasted groups. Food intake restriction to one‐third of satiety levels was enough to trigger the mechanisms that preserve essential fatty acids.     

Meristic character analysis and skeletal anomalies during growth in reared sharpsnout seabream

Sharpsnout seabream (Diplodus puntazzo) is a speciescurrently reared in Mediterranean fish farms. In order to detect themain types of body deformation in sharpsnout seabream, 120 specimens (60juveniles and 60 adults) taken from a Mediterranean hatchery wereexamined. In juveniles and adults non-significant differences were foundin the number of vertebrae, dorsal spines and pectoral fin rays.Moreover, the number of anomalies varied with age. The juvenilespresented 28 types of anomaly, the adults 25. The most importantanomalies for juveniles (in terms of frequency of occurrence) wereanomalous neural arch or spine (47%), anomalous hemal arch orspine (43%), fusion of hypurals (67%) and presence ofcalculi in the terminal tract of urinary ducts (43%), while foradults were anomalous neural arch or spine (43%), fusion ofhypurals (90%) and fusion of epurals (37%). Whileanomalous hemal arch or spine and presence of calculi in the terminaltract of urinary ducts decreased with age, fusion of hypurals and fusionof epurals increased. Lordosis and kyphosis were found in a slight formonly in juveniles and with a low frequency of occurrence. Thesedecreased or disappeared in adults. No mortality was detected either injuveniles or in adults. In any case, these anomalies did not influencethe growth performance of juveniles and no lethal anomalies weredetected.     

Mono- and duoculture of juvenile sharpsnout seabream Diplodus puntazzo (Cetti) and gilthead seabream Sparus aurata L. in a recirculated water system

Although the growth of intensively reared sharpsnout seabream Diplodus puntazzo (DP) has been suggested to improve in duoculture with gilthead seabream Sparus aurata (SA), the stocking ratio for most effective duoculture rearing has not been investigated. For this purpose, juvenile D. puntazzo (1.68±0.011 g) and S. aurata (1.43±0.007 g) were reared in duplicated groups of 165 specimens each, in two monoculture (100% DP, 100% SA) and four duoculture combinations (80% DP–20% SA, 60% DP–40% SA, 40% DP–60% SA, 20% DP–80% SA) for 96 days under recirculated water system conditions. Both species exhibited the highest growth when stocked at 20% and the poorest growth when stocked at 80%. For each species, no major differences for coefficient of weight variation and carcass proximate composition were detected. As the percentage of stocked S. aurata increased, D. puntazzo aggressiveness and weight variability of whole population were reduced, while total biomass, food consumption and food conversion ratio were increased. The results obtained are discussed in relation to fish behaviour and social interactions. From the fish farming point of view, it is indicated that under the present experimental conditions, juvenile S. aurata should be reared in monoculture and D. puntazzo in duoculture 40% DP–60% SA.     

Fish oil substitution by soybean oil in Sharpsnout seabream Diplodus puntazzo: Performance,fatty acid profile,and liver histology

The present study was conducted to determine the effect of soybean oil on the performance and liver histology in Sharpsnout seabream (Diplodus puntazzo) (initial body mass 35 g). Four experimental diets were formulated containing 0%, 25%, 50%, and 75% of soybean oil substituting fish oil. Fish were fed for 84 days. Increasing the level of soybean oil had no significant effects on growth and feed efficiency parameters. Biometrics, body composition, protein efficiency, and energy efficiency were not affected by the fish oil replacement. Muscle and liver fatty acids reflected fish oil substitution. Moreover, histology did not show statistical differences among treatments. Sharpsnout seabream juveniles can be fed with diets in which fish oil has been replaced with soybean oil at up to 75% of total lipid in the diet for a period of 84 days without affecting growth, feed efficiency, biometric parameters, and body composition.     

Seasonal condition and body composition changes in sharpsnout seabream (Diplodus puntazzo) raised in captivity

Changes in biological indices (weight, length, gonadosomatic index, condition factor, hepatosomatic index, intraperitoneal fat ratio and fillet portion), and body composition were examined in sharpsnout seabream (30 to 500 g) maintained in culture for one and a half years. Growth was rapid during May–September, and slow from October to April. Gonadal development took place between August and October, and gonadosomatic index peaked in October (GSI: 1.14%). The condition factor, the hepatosomatic index and the intraperitoneal fat ratio varied (CF: 1.83–2.51, HSI: 0.80–2.47%, IPF ratio: 1.27–2.95%, minimum and maximum values, respectively), falling during the warmer months of the year (May–Oct). The fillet portion (the eviscerated fish with the head, fishbone and tail removed), represented a 55% of body mass. There were inverse correlations between relative fat and moisture contents associated with growth periods and sexual maturation (fat: 13.5–18.5%, moisture: 59.9–64.6%, minimum and maximum values, respectively), whereas proportions of minerals and protein were more stable (ash: 3.8–4.8%, proteins: 17.5–21.4%, minimum and maximum values, respectively).     

Morphoecology in larval fin-fish: a new candidate species for aquaculture, Diplodus puntazzo (Sparidae)

This study was aimed to acquire information ontrophic behavior of Diplodus puntazzolarvae and juveniles, by studing theontogenetic sensory development, except vision.D. puntazzo specimens were observed usinga scanning electron (n = 67) and a lightmicroscope (n = 7). The results concerned fourontogenetical stages of sharpsnout seabream:larval, post-larval, transitional, and juvenilestages. The yolk-sac larval stage was notdetected as the smallest larvae at our disposal(3.1 mm TL; 2nd day from hatching) showedno external appearance of the yolk. During thelarval stage (3.1–4.7 mm TL), sharpsnoutseabream is equipped with free neuromasts andolfactory ciliated receptor cells. In thepost-larval stage (5–28.6 mm TL), mechano- andchemo-reception is implemented: the inner andouter taste buds differentiation, the nasalformation, the lateral line system canalizationoccur. The precocious differentiation ofchemo-receptors makes post-larvae particularlysensitive to the organoleptic properties ofadministered preys. D. puntazzo, at theend of this phase, could be considered ajuvenile (complete squamation is acquired),except for the mouth and pharyngeal teeth.During the subsequent phase (`transitional'),in fact, eight chisel-type and two lateralseries of molar-like teeth progressivelysubstituted the conical ones on each jaw, andthree different types of teeth on the upper andlower pharynx differentiated. So, the juvenilephase is reached in individuals longer than58 mm TL.     

The kinetic profile of oxolinic acid in sharpsnout sea bream, Diplodus puntazzo (Cetti 1777)

The pharmacokinetics of oxolinic acid (OA) were investigated after a single intra‐vascular injection (20 mg kg^?1 fish) in sharpsnout sea bream (90 g), a promising new euryhaline species for Mediterranean fish farming. The distribution half‐life (t_1/2α) and the elimination half‐life (t_1/2β) of OA were calculated to be 0.4 and 10 h respectively. The apparent volume of distribution at steady‐state (V_d(ss)) and total clearance rate (CL_T) of the drug were found to be 2.1 L kg and 0.2 L kg^?1 h^?1 respectively. The bioavailability (F%) of OA following oral administration (40 mg kg^?1 fish) was estimated to be 15%. The results indicate a rapid distribution and elimination of the drug, moderate tissue penetration, but low absorption in sharpsnout sea bream. The kinetic profile of OA found in this species is comparable with that observed in another well‐known sparid, gilthead sea bream.     

Meristic character counts and incidence of skeletal anomalies in the wild Diplodus puntazzo (Cetti, 1777) of an area of the south-eastern Mediterranean Sea

The sharpsnout seabream (Diplodus puntazzo, Cetti 1777) is a species rarely found in coastal areas of Sicily, but is important in Mediterranean aquaculture. In order to detect the number of meristic characters and the main types of body deformation, 588 specimens of sharpsnout seabream were collected from a coastal zone of south-east Sicily (Licata, AG—Italy). Different sized classes were examined and the relationship between size and the number of meristic characters (number of fin rays) was found. The number of vertebrae, anal fin hard rays and dorsal fin hard rays was constant and did not vary with size. Seventeen types of skeletal and fin anomalies were observed, but no grave anomalies were found, such as the absence of a swimbladder, lordosis, kyphosis and calculi in the terminal tract of the urinary duct. The most prevalent anomalies were associated with the fins, especially E7 (pectoral fin rays), F7 (anal fin rays) and I7 (dorsal fin soft rays). There was no correlation between frequency of anomaly and size class. The malformation index was 4.54.     

Shape ontogeny and variation in the sharpsnout seabream, Diplodus puntazzo (Cetti 1777)

Shape ontogeny of Diplodus puntazzo was studied during the larval and metamorphosis phase (2.6–33.0 mm total length (TL)) by means of geometric morphometrics. Additionally, shape comparison was performed between newly settled wild individuals of D. puntazzo (11.0–18.0 mm TL) and reared of the same TL range. Results clearly demonstrated that shape ontogeny of D. puntazzo is not continuous during the studied period, but it is characterized by the presence of two inflection points (at 6.2 and 11.4 mm TL), which define three phases of significantly different rates of shape development (P<0.05). Spline diagrams demonstrated that shape ontogeny mainly correlated with the development of fins, caudal peduncle, snoot and the ventral abdominal profile. Concerning the comparison of reared fish with wild fish, morphometric analysis revealed a significant effect of fish origin on the shape of D. puntazzo (Wilks' λ=0.147, P<0.001). Shape differences between the two populations were mainly demonstrated at the caudal peduncle and at the ventral profile of the abdominal area. Combined with the results of shape ontogeny, spline diagrams showed that shape differences between the two populations were related to the comparatively more advanced ontogenetic state of reared fish, at the studied size range.     

Dietary self-selection in sharpsnout seabream (Diplodus puntazzo) fed paired macronutrient feeds and challenged with protein dilution

Macronutrient selection and responses to dietary protein dilution were investigated in 95-g sharpsnout seabream, an omnivorous fish species of interest for Mediterranean aquaculture. Five groups of 18 sharpsnout seabream were distributed among circular 450-l tanks and allowed to self-feed from 3 feeders each of which distributed feeds composed of different pairs of macronutrients: PC (75% protein, 25% carbohydrate), PF (75% protein, 25% fat) or FC (50% fat, 50% digestible carbohydrate). Regardless of self-feeders position, the fish composed a diet containing 63% protein, 19% fat and 18% carbohydrate. When the protein-containing diets (PC and PF) were diluted 50% with cellulose, the fish increased their food intake to compensate for the energy dilution (170 kJ/kg BW/day vs. 168 kJ/kg BW/day after dilution), and dietary composition (63% protein, 16% fat and 21% carbohydrate) did not change significantly. These results demonstrate that sharpsnout seabream can select from incomplete diets to compose a balanced diet, and the fish are also able to compensate for a dietary dilution to regulate both energy intake and the relative proportions of macronutrients.     

Heritability of skeleton abnormalities (lordosis, lack of operculum) in gilthead seabream (Sparus aurata) supported by microsatellite family data

Body abnormalities constitute an important problem to fish aquaculture. Pigmentation, scale and skeleton abnormalities have been reported in different cultured fish species. Environmental and genetic factors or their interaction have been suggested to explain their origin. Gilthead seabream (Sparus aurata) is one of the most important European cultured species. Lordosis and lack of operculum are common abnormalities in this species, and can reach frequency of 80% or more of commercial batches. In spite of an important body of data suggesting environmental factors related with their origin, scarce and not conclusive genetic data have been reported to date. In our study, a large number of families originating from the usual production process of a commercial farm were used to estimate the heritabilities of both characters. Two independent experiments were carried out for each abnormality. Nine hundred and ninety four (5.6% lordotics; 157 full-sib families; 6.3 offspring/family) and 808 (7.9% lacking operculum; 83 families; 9.7 offspring/family) individuals were used for lordosis and lacking operculum heritability estimations, respectively. The results obtained adjusting an animal model indicated non significant heritabilities for both characters (0.021 (s.e. 0.019) and 0.032 (s.e. 0.023) for lordosis and lack of operculum, respectively). The corresponding values when a threshold model was used, though higher (0.152 and 0.203, respectively), evidenced large standard errors (0.119 and 0.146, respectively) suggesting h² = 0 as the most confident hypothesis (P = 0.838 and 0.766, respectively). A non-parametric permutation test was also applied to evaluate if more related individuals had a higher phenotypic resemblance. The results obtained suggested only a slight familiar association (P < 0.05) when comparing individuals lacking operculum, but neither between lordotics nor between normal ones. These results suggest that most phenotypic variation observed for lordosis and lack of operculum in gilthead seabream is due to environmental factors.     

Effect of an experimental microparticulate diet on the growth, survival and fatty acid profile of gilthead seabream (Sparus aurata L.) larvae

In recent years, a great deal of interest has emerged in the development of microdiets as an economic alternative to live food, in the larval culture of marine fish species. The ability to grow Sparus aurata larvae on a prototype microparticulate diet was examined. To achieve this objective, four feeding regimes differing in the time when the microdiet was introduced (3, 7 or 12 days) and one based exclusively on an inert diet were tested, during the first 22 days of larval life. Significant differences in larval growth were found between the experimental feeding regimes and their corresponding controls (enriched rotifers during the whole experimental period); the larvae in the co-feeding regimes and with an exclusive microparticulate diet were always significantly smaller than larvae fed on rotifers alone. However, the difference was minimised by introducing the inert diet at a later date. A lower survival was found in larvae with a co-feeding regime, in comparison with the control treatments and the survival was significantly lower in larvae fed exclusively on a microparticulate diet. The fatty acid analysis revealed that the experimental microencapsulated diet and the rotifers enriched with Protein Selco® presented relatively similar fatty acid content. In spite of the slightly higher (n?3)/(n?6) and Docosahexaenoic acid (DHA)/Eicosapentaenoic acid (EPA) ratios and somewhat lower highly unsaturated fatty acid (HUFA) content found in the inert diet, the fatty acid composition of the diets cannot explain the differences found in larval performance. The results revealed that the complete replacement of live prey with the tested microparticulate diet is still not possible in S. aurata larval rearing. Nevertheless, better growth and survival results and a substantial reduction in the daily supply of live food can be achieved with a combination of microdiet and live prey.     

Alteration of liver and muscle fatty acid composition in gilthead seabream (Sparus aurata) juveniles held at high stocking density and fed an essential fatty acid deficient diet

The aim of the present study was to determine the combined effect of both stress and EFA deficiency on several biological and biochemical parameters. Fish were fed during 15 weeks two isocaloric and isoproteic diets: a control diet based on fish oil and formulated to meet the n-3 HUFA requirements for this species (1.5% of n-3 HUFA) and a deficient diet containing beef tallow and formulated to be deficient in n-3 HUFA. Each experimental diet was evaluated both at high and low stocking densities (10 and 3.2 kg m^–3 of initial density, respectively).High stocking density produced a chronic stress situation with elevation of plasma cortisol levels. It also caused a reduction in hepatosomatic index and liver lipid contents, increasing the oleic acid/n-3 HUFA ratios in the polar lipids. Fish fed the EFA deficient diet at low stocking density showed common deficiency symptoms. High stocking density in fish fed the EFA deficient diet induced a higher degree of EFA deficiency symptoms leading to mortality, liver steatosis, liver lipid deposition, reduced muscle lipid and reduced n-3 HUFA contents, which particularly affected EPA, but not DHA, suggesting a preferential retention of the latter fatty acid, specially in the phosphoglycerides fraction.     

Haematological, biochemical and immunological parameters as stress indicators in Dicentrarchus labrax and Sparus aurata farmed in off-shore cages

In 2000–2001, an investigation was performed in two Sicilian mariculture sites (Pachino and Castellammare) to monitor physiological and biochemical parameters in sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) specimens farmed in off-shore sea cages. Plasma cortisol and glucose levels, tissue lactate concentration, haematocrit and haemoglobin content, lysozyme, haemolytic and haemagglutinating activities were determined. During the experiment, an increase in tissue lactate and plasma cortisol levels and a reduction in haemolytic and haemagglutinating titers, were recorded. Changes occurring in these haematological, immunological and biochemical values suggest that these parameters can be useful indicators in assessing the condition of chronic stress induced by mariculture operations.