Dicentrarchus Labrax

Carillo, M., Bromage, N., Zanuy, S., Serrano, R., and Prat, F., 1989. The effect of modifications in photoperiod on spawning time, ovarian development and egg quality in the sea bass (Dicentrarchus labrux L.). Aquaculture, 81: 351-365. Under simulated natural conditions female sea bass (Dicentrurchus labrax) in eastern Spain (latitude 4O"N and longitude 0" ) spawned over a 6-8-week period in February and March, with 0044-8486/89,'$03.50 0 1989 Elsevier Science Publishers B.V. M. CARRILU) ET AL.

As alternative farming methods, we investigate growth, haematological, biochemical and immunological parameters of European sea bass (Dicentrarchus labrax) farmed in submersible cages in order to compare physiological status under different rearing conditions and to validate the efficacy of submersible technology in solving several of the substantial problems that exist in surface-based fish farming as heavy storms, algal and jellyfish blooms and attacks by predators. The study was conducted in 2008 in the Gulf of Castellammare (NW Sicily, Mediterranean Sea) in two submerged and two surface cages filled with 75.000 D. labrax (initial weight: 28.2 ± 4.3 gr), for each cage. No significant differences were shown in specific growth rate between the two groups, even if, fish cultured in submerged cage reached the largest size. Results from biochemical and haematological parameters examined indicated higher welfare state in fish cultured in submerged cages. Fish reared in surface cages showed a significantly higher blood cortisol and glucose levels and haematocrit value than those of submerged cages. Also lysozme and haemolytic activity, used as indicators of immunocompetence in fish exposed to stress, lead us to suppose that submergence could have a positive effect on some components of innate immune system of cultured fish. Results of this study suggest mariculture in submerged net cages a promising system that allows to minimize stress and therefore that favours animal welfare.

European sea bass Dicentrarchus labrax from the Mediterranean were diagnosed with a severe encephalitis. Rickettsia-like organisms (RLOs) were associated with brain lesions in routine paraffin sections. These were found to share common antigens with the Piscirickettsia salmonis typestrain, LF-89, by indirect fluorescent antibody test (IFAT) and by immunohistochemistry (IHC). In addition, we compared the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) with those published for P. salmonis strains and found that the sea bass piscirickettsialike organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. Furthermore, we showed that the SBPLO possessed at least 2 ITS regions, 1 of which contained tRNA genes.

Condition of overwintering European sea bass, Dicentrarchus lubrax. was studied in salt marshes along the French Atlantic coast. The somatic and liver condition indices (K and LSI, respectively) and RNA: DNA ratio were determined over a period of 5 months (October '89-February '90). K, LSI and RNA: DNA were high in October and this was attributed to the fish's physiological preparation in autumn for the overwintering phase. In the age-1 teleost studied here this preparatory growth was linked to anticipated inclement temperature and not to gonad maturation. Decline in K and LSI started in November and continued till January but improvement was noticed in February. RNA: DNA ratio decreased till December, rose in January and remained stable in February. Magnitude of change was greater in LSI than in K. RNA: DNA was more sensitive compared to K and LX Low temperature in winter resulted in decrease in K, LSI and RNA:DNA through decline of food intake and slowing of metabolism. Discordancy in the pattern of change in the midst of winter demonstrated a more prompt response of RNA: DNA to environment. Recovery of the three parameters in the second half of winter was attributed to sea bass undergoing compensatory growth with a favourable turn in the thermal regime and, of course, after developing adaptation to cold.

In this study, bioaccumulation of the heavy metals (Fe, Zn, Cd) in the liver, gill, gonad and muscle tissues of Dicentrarchus labrax, Mugil cephalus and Sparus aurata were investigated seasonally. amlık is the important fisheries lagoon located in The Iskenderun Bay, Mediterranean cost of Turkey. Due to heavy industrial and agricultural activities in the region, the bay has the polluted

A genetic linkage map of the European sea bass (Dicentrarchus labrax) was constructed from 174 microsatellite markers, including 145 new markers reported in this study. The mapping panel was derived from farmed sea bass from the North Adriatic Sea and consisted of a single family including both parents and 50 full-sib progeny (biparental diploids). A total of 162 microsatellites were mapped in 25 linkage groups. Eleven loci represent type I (coding) markers; 2 loci are located within the peptide Y (linkage group 1) and cytochrome P450 aromatase (linkage group 6) genes. The sex-averaged map spans 814.5 cM of the sea bass genome. The female map covers 905.9 cM, whereas the male map covers only 567.4 cM. The constructed map represents the first linkage map of European sea bass, one of the most important aquaculture species in Europe.

The paper reports the results of an experimental seismic survey in the open sea by an air gun, carried out to evaluate the eects of air gun acoustic waves on marine animals. Air gun blast exposition was found to have a marked in¯uence on con®ned Dicentrarchus labrax. Our data, in fact, demonstrated a biochemical response to acoustic stress induced by air gun blasts. Variations of cortisol, glucose, lactate, AMP, ADP, ATP and cAMP in dierent tissues of D. labrax, indicate that ®sh have a typical primary and secondary stress response after air gun detonations. Radiography indicates that air gun blasts do not induce any macroscopic eect on skeletal apparatus. The variations of biochemical parameters returned within physiological values within 72 h indicating a rapid recovery of homeostasis after acoustic stress and no mortality was observed. Ó

This study evaluated the effects of replacing fish meal (FM) in the diet of European sea bass (Dicentrarchus labrax) with differently processed soybean meals on growth performance; apparent digestibility coefficients (ADCs); the activity of alkaline phosphatase and the brush border digestive enzymes: leucine amino peptidase, maltase and γ-glutamyl transpeptidase; and the fish morphometric and flesh quality. European sea bass with an initial average body weight of 187.8 ± 1.4 g, were fed either a FM based (control) diet or a soy replacement isoproteic, isolipidic and isocaloric diet. The treatments consisted replacing FM protein by: 25% toasted, dehulled and solvent-extracted soybean meal (SE25); 50% dehulled and toasted soy seeds subjected to dry extrusion and mechanical oil extraction (ME50); 50% enzyme-treated soybean meal (ET50) and an inclusion of 60% composed of 30% toasted, dehulled and solvent-extracted soybean meal and 30% enzyme-treated soybean meal (SE + ET/60). ADCs values of dry matter, crude protein, crude lipid and gross energy did not significantly differ between ME50 and SE + ET/60 but both of them were inferior to the other treatments (P < 0.05). Compared with the control FM-based diet, only the group that consumed the ME50 diet had lower specific growth rate, feed conversion ratio and gross protein retention efficiency values (P < 0.05). The protein efficiency ratio did not differ between the FM-based control group and all other soy derivate groups (P > 0.05). In order to gain more insight on the effects of the diet on fish growth, activity of the brush border enzymes was measured. No significant differences were found in leucine amino peptidase and maltase activities, between the control group and the other soy derivate groups. The activity of γglutamyl transpeptidase was significantly higher in the upper section in fish that consumed the control diet compared with fish that consumed the soy derivate diets. Yet, the main activity of this enzyme was found in the lower intestinal section. In all the soy derivate diets except for the SE25 diet, the activity of alkaline phosphatase was significantly lower than its activity in the control diet. Feeding diets that include various types and levels of soybean derivatives did not affect the whole body composition and slaughter yield but significantly reduced liver weight. The results show that in methionine supplemented diets, FM can be replaced in terms of protein by 25% SE, 50% ET or 60% soy composed of 30% SE and 30% ET without hampering fish performance. The inclusion of 50% protein from ME resulted in significantly lower growth performance and feed utilization.

Özet: Farklı tank tiplerinin levrek (Dicentrarchus labrax L., 1758) larvasının büyüme ve yaşama oranları üzerine etkileri. Bu çalışmada, farklı tank tiplerinin levrek larvası yaşama, gelişim ve büyüme oranları üzerindeki etkileri araştırılmıştır. Bunun için, yaygın olarak kullanılan farklı şekil, hacim, derinlik ve yüzey alanına sahip 3 farklı tipte (sırasıyla A, B ve C) larva tankı kullanılmıştır. Her tank tipi için iki tekrar gerçekleştirilmiş olup, her bir tanka 100 g/m³ oranında yumurta stoklanmıştır. Yumurtadan çıkıştan sonra, larval yetiştiricilik aynı tanklarda intensif akışkanlı su yöntemi ile 60. güne kadar sürdürülmüştür. Ayrıca 60. günde, hava keseli ve hava kesesiz tüm larvalar sayılmış ve her bir tanktan rasgele seçilen 100 larvanın yaş ağırlığı ve total boyu ölçülmüştür. C tanklarındaki larvaların yaşama oranı hem A hem de B tanklarındaki larvaların yaşama oranından daha yüksek olmuştur (p<0.05). Yaşama oranlarına benzer şekilde, C tanklarındaki larvaların hava kesesi geliştirme oranı hem A hem de B tanklarındakinden daha yüksektir (p<0.05). Bununla birlikte, üç tank tipindeki hava keseli larva oranları arasında ise önemli bir fark görülmemiştir (p>0.05). En düşük ortalama yaş ağırlık değeri C tanklarında kaydedilirken, en yüksek ortalama yaş ağırlık değeri A tanklarında elde edilmiştir. Fakat hem A hem de B tanklarında ortalama total boy değerleri C tanklarında kaydedilen değerden daha yüksek bulunmuştur (p<0.05). Bu çalışma intensif akışkanlı su yetiştiricilik tekniğinde kullanılan tank tipinin levrek larvasının hava kesesi geliştirme ve yaşama oranları üzerinde önemli etkileri olduğunu göstermiştir. Karşılaştırılan tank tipleri arasında, silindirik-konik C tipi tanklar, özellikle ilk 45 günlük larval dönem için en uygun fiziksel ortamı sağlamıştır. Ancak, larvanın bu tip tanklarda 45 günden daha uzun süre tutulması büyümenin yavaşlamasına neden olabilmektedir. Kırk beş gün sonunda larvanın A veya B tipi tanklara nakledilmesi ile daha yüksek büyüme ve yaşama oranları elde edilebilir. Çünkü daha geniş yüzey alanına ve hacme sahip olan bu tip tanklar larvanın yapay yeme alıştırılması için daha uygun bir ortam sağladıkları gibi yapay yem ile besleme sırasında karşılaşılan su kalitesinde sorunlarının hafifletilmesine yardımcı olabilirler.

Histology revealed scattered lymphoid cells at all levels of the digestive tract of the sea bass Dicentrarchus labrax (L.), notably in the mucosa and submucosa. Immunohistochemistry with monoclonal antibodies against T cells (DLT15) and immunoglobulin-bearing cells (DLIg3 and DLIg13) demonstrated the presence of a gut-associated lymphoid tissue. Quantitative analysis showed that the concentration of DLT15-positive cells largely exceeded that of Ig-bearing cells, while the number and the distribution of DLIg3-and DLIg13immunoreactive cells were superimposable. An apparent gradient in the number of lymphoid cells was present, concentrating them towards the anus. This suggests that, as in other fish species, the posterior gut acquired higher immunological relevance.

The mortality of juvenile European sea bass, Dicentrarchus labrax (L.), in the spring of the last 5 years in the northern coast of the Adriatic Sea has been attributed to heavy infections of the gill monogenean Diplectanum aequans (Wagener 1857) Diesing 1858. The histopathological examination of 38 sets of gills from hosts measuring 16.46±0.26 cm in total length (mean±S.E.) and weighing 45.98±2.37 g (mean±S.E.) were conducted using light and transmission electron microscopy. Twenty-eight (73.6%) D. labrax specimens were infected (34.61±4.42, mean inten-sity±S.E.; 5-100, range) with the majority of D. aequans attaching to the median and apical portions of the primary gill filaments. The sites of attachment were marked by the common presence of haemorrhages and a white mucoid exudate. In histological sections, the opisthaptors of the parasites were observed to penetrate deeply, lying in close proximity to the basal membrane of primary lamella where they induced a hyperplastic response. Disruption and fusion of the secondary lamellae were common in all infected specimens with several individuals also exhibiting a marked erosion and inflammation of the epithelium of the primary and secondary lamellae. In infected fish, cellular changes in the epithelium underlying the bodies of worms were noted typified by an elevation in the number of mucous and rodlet cells and a reduction in the number of chloride cells.

European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate the ecological and economic importance of the saltmarsh habitat. This study was the first in Great Britain to investigate the seasonal changes of salt marsh fish communities and the variation in community structure between closely located marsh habitats. Between February 2007 and March 2008, five marshes on three estuaries of the Essex coastline were sampled using flume nets to block off intertidal creeks at high tide. Fourteen fish species were caught. The community overall was dominated by three species that made up 91.6% of the total catch: the common goby Pomatoschistus microps (46.2% of the total catch), juvenile herring Clupea harengus (24.3%), and juvenile and larval sea bass Dicentrarchus labrax (21.2%). Cluster analysis demonstrated clear seasonal patterns, with some community structures unique to specific marshes or estuaries. The marsh fish community shifts from a highly diverse community during spring, to a community dominated by D. labrax and P. microps in autumn, and low diversity during winter months. Gravimetric stomach content analysis of fish community identified three main trophic guilds; macroinvertivores, planktivores and omnivores. The macroinvertivore feeding guild contained D. labrax and P. microps, the two most frequently occurring species. This investigation demonstrates the importance of British salt marshes as nursery habitats for commercial fish species.

Under culture conditions, sex ratios in the European sea bass (Dicentrarchus labrax L.) are consistently skewed in favor of males. Moreover, no heteromorphic sex chromosomes have been shown for this species. This bias towards males could be due to a possible effect of environmental factors on sex differentiation, as has already been described in other fish species. To test this hypothesis, sexually undifferentiated sea bass were reared under two different thermal regimes or two different photoperiodic regimes, resulting in four groups: Group SP = short photoperiod (9 hours light [L]:15 hours dark [D]), Group LP = long photoperiod (15 L:9 D), both reared under natural temperature (24°C, average); Group LT = low temperature (15°C), Group HT = high temperature (25°C), both reared under natural photoperiod (13.5 L:10.75 D, average). Treatments lasted 80 days, from 57 to 137 days post fertilization, coinciding with the time when gonads are more sensitive to the action of exogenous sex steroids. The resulting sex proportions were determined by periodic histological examinations of the gonads during the first 2 years of age. No females were found in group LT at any sampling, whereas in the other groups, female proportions never reached values higher than 27%. Moreover, sex differentiation in group LT was delayed with respect to the other groups, as no fish completed sex differentiation until 16.4 months of age, compared to the other groups in which some individuals completed sex differentiation at 9 months of age. In addition, growth was significantly (P < 0.05) delayed in group LT with respect to the other three experimental groups and especially marked during the first year of life. Furthermore, the low values for the gonadosomatic index (GSI), together with the decrease of the number of spermatogenic males, denote a delay in gonadal maturation with respect to the rest of the experimental groups. The results of this study suggest that temperature can play an important role in the process of sex differentiation and growth of the sea bass. However, the mechanism(s) underlying this sexual lability remain unknown.

European sea bass (Dicentrarchus labrax) is one of the finfish species preferred by the consumer, who requires fish freshness to be maintained during distribution and retail. For this reason, the purposes of this study were to define: the shelf life at three storage temperatures (À0.5, 4.8 and 16.5 C) by applying both chemical (TVB and TBA assays) and olfactometric (e-nose) method; the actual time-temperature exposure conditions during marketing; the prediction of remaining shelf life in the commercial chain, on the basis of time-temperature history data and on appropriate integration routine. Shelf life study revealed the efficacy of chemical markers and electronic nose in describing the freshness decay and in defining a freshness threshold. Freshness of sea bass was kept for about 8 days for fish preserved in melting ice (À0.5 C), 4 days at 4.8 C and about 1 day at 16.5 C. When fresh European sea bass was purchased, 9 out of 10 times the remaining shelf life was more than 55% at an average temperature of 1.19 C. Therefore, the freshness of fish can be assured for 3-4 days in commercialization. A joint effort (sales point management and consumer advertising) could reduce the exposure temperature by 1-2 C and justify an extension of the shelf life to 2-3 days after purchase. (M. Riva). 1 We dedicate this work to the memory of prof. Marco Riva who died unexpectedly during the revision of the paper. A valued colleague and scientist.

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.

Selection of protective cultures is relevant in order to biopreserve and improve the functional safety of food products, mainly through inhibition of spoilage and/or pathogenic bacteria. Accordingly, the present study investigated potential applications of lactic acid bacteria (LAB) in the biopreservation of fish and shellfish products. For this purpose, a collection of 84 LAB strains isolated from sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) was identified and characterized for their inhibitory activities against the most relevant seafood-spoilage and pathogenic bacteria potentially present in commercial products. The bioactive strains belonged to the genus Enterococcus and exhibited inhibition against Carnobacterium sp, Bacillus sp, Listeria monocytogenes, Aeromonas salmonicida, Aeromonas hydrophila and Vibrio anguillarum. Treatment of cell-free extracts of the LAB strains with proteases revealed the proteinaceous nature of the inhibition. Interestingly, the cell-free extracts containing bacteriocins remained 100% active after treatment up to 100 C for 30 min or 121 C for 15 min. Molecular analysis led to identification of the bacteriocins investigated, including enterocins A, B, L50 and P. All of these proteins demonstrated remarkable anti-Listeria activity and were found to be heat-resistant small class IIa bacteriocins. The results presented in this work open the way for potential applications of these LAB strains to the biopreservation of minimally-processed seafood products.

Özet: Farkli tank tiplerinin levrek (Dicentrarchus labrax L., 1758) larvasinin büyüme ve yaşama oranlari üzerine etkileri. Bu çalişmada, farkli tank tiplerinin levrek larvasi yaşama, gelişim ve büyüme oranlari üzerindeki etkileri araştirilmiştir. Bunun için, yaygin olarak kullanilan farkli şekil, hacim, derinlik ve yüzey alanina sahip 3 farkli tipte (sirasiyla A, B ve C) larva tanki kullanilmiştir. Her tank tipi için iki tekrar gerçekleştirilmiş olup, her bir tanka 100 g/m³ oraninda yumurta stoklanmiştir. Yumurtadan çikiştan sonra, larval yetiştiricilik ayni tanklarda intensif akişkanli su yöntemi ile 60. güne kadar sürdürülmüştür. Ayrica 60. günde, hava keseli ve hava kesesiz tüm larvalar sayilmiş ve her bir tanktan rasgele seçilen 100 larvanin yaş ağirliği ve total boyu ölçülmüştür. C tanklarindaki larvalarin yaşama orani hem A hem de B tanklarindaki larvalarin yaşama oranindan daha yüksek olmuştur (p&lt;0.05). Yaşama oranlarina benzer şekilde, C tanklarindaki larvalarin hava kese...

Three potentially valuable red seaweeds, Chondrus crispus Stackhouse, Gracilaria bursa pastoris (S.G. Gmelin) P.C. Silva and Palmaria palmata (L.) O. Kuntze, collected in northern Portugal, were cultivated using the nutrient-rich effluents from a local turbot (Scophthalmus maximus Linnaeus) and sea bass (Dicentrarchus labrax Linnaeus) farm. The algae were cultivated in a two level cascade system. Several arrangements of the cascade

Stocking density is considered a priority topic in aquaculture research due to its bearing on the welfare of farmed fish and the need for future recommendations governing stocking density management on fish farms. In this study, two consecutive experiments were carried out in order to investigate the physiological response of sea bass Dicentrarchus labrax to different stocking densities and to an acute stress challenge. Three duplicate groups of sea bass (mean BW = 139.8 g; TL = 18.6 cm) were reared in six recirculating tanks (5 m 3 ) at three stocking densities (15, 30 and 45 kg/m 3 ) for 6 weeks, and then crowded at 100 kg/m 3 for 15 min. Sampling was performed after 2 weeks and at the end of the stocking density experiment (6 weeks) and at 1, 6, 24, 48, 72 h and 10 days after crowding. Blood samples were analyzed for cortisol, glucose, nonesterified fatty acids (NEFA), total proteins, triglycerides and cholesterol concentrations. Univariate and multivariate analyses were applied to the data sets. No differences in growth and survival were observed in sea bass kept at 15, 30 and 45 kg/m 3 for 6 weeks. Serum cortisol levels measured at 2 and 6 weeks were not significantly different among density groups. A significant increase in NEFA concentration was observed in sea bass kept at 45 kg/m 3 after 6 weeks, suggesting enhanced lipid mobilization.

Sea bass (Dicentrarchus labrax) (135 AE 4 g) were reared under tank-based recirculating aquaculture system for a 63-day period at four densities: 10, 40, 70, 100 kg m À3 . Fish performance, stress indicators (plasma cortisol, proteonemia plus other blood parameters-Na + , K + , glucose, pH, total CO 2 À ) and water quality were monitored. At the end of the 63-day period, resistance to infection was also studied by a nodavirus challenge. A 25-day test was performed on fish from two extreme densities (10 and 100 kg m 3 ) and one intermediate density (40 kg m 3 ).

The aim of this study is to determine the quality changes in whole ungutted sea bass and sea bream while stored in ice. Changes in chemical quality were determined by using pH, total volatile basic nitrogen (TVB-N, mg N/100 g), trimethylamine (TMA-N, mg/100 g), thiobarbituric acid (TBA, mg malonaldehyde/kg), water activity (a w ), color measurement, and sensory analysis. Changes in microbiological quality were determined by using the analysis of total viable mesophilic and psychrophilic bacterial counts. Result of this study indicated that the shelf life of sea bass and sea bream stored in ice as determined by overall acceptability sensory scores and microbiological data was 15 days.

In a parasitic survey of wild and cultured sea bass, Dicentrarchus labrax (L.), thirteen protozoan species were found. Ectoparasites included two ciliates {Trichodina spp.), one dinoflagellate {Amylodinium sp.) and one zooliagellate {Cryptobia sp.). Endoparasites were represented by members of Apicomplexa {Hemogregarina sp.. Eimeria spp.). Microsporea (unidentified species) and Myxosporea {Myxobilatus sp,, Ceratomyxa spp,. Sphaerospora dicentrarchi, Sphaerospora testicularis). Myxobilatus sp., Eimeria spp. and the microsporean were exclusively found in wild fish, whereas Amyloodinium sp. and Hemogregarina sp. were only detected in cultured fish. Data on prevalence and intensity of infections and on the location in the host are provided. The potential importance of protozoan parasites for sea bass culture is discussed.

Growth, feed conversion efficiency, fillet composition and morphological indices of European sea bass (initial weight of 2.6 F 0.3 g) were investigated in a 6 Â 2 factorial designed experiment employing two salinities [seawater (SW, 40 ppt) and freshwater (FW, 0.4 ppt)] and six different feeding rates (2.0%, 2.5%, 3.0%, 3.5%, 4.0% of their body weight (bw) day À 1 and to satiation) for 60 days. Twenty fish were stocked into 155-l round tanks and each treatment had three replicate tanks. Throughout the experiment, weight gain and specific growth rate (SGR) were highest at ration 4.0 bw day À 1 and to satiation in SW group. Regardless of feeding rate, sea bass fingerlings grew about 20 -30% more in SW than those reared in FW. There was a significant ( P < 0.05) interactive effect of feeding rates and culture media (SW and FW) on weight gain and feed conversion efficiency (FCE). FCE was found to be lower in fish fed to satiation (65 -66%) compared to the feeding rate of 3.5% bw day À 1 , which was best in both SW (89.1%) and FW (86.5%). There were no significant differences in either protein or ash contents of the fish cultured in SW or FW although lipid and moisture contents changed with increasing feeding rate. Condition factor, fillet yield and carcass/body weight were significantly increased, whereas hepatosomatic index, viscera somatic index decreased when the feeding rate was increased above 2.0% bw day À 1 . Feeding rate proved to be the main differentiating factor in all growth, FCE and fillet composition parameters. Values of SGR plotted against feeding rates allowed the maintenance, optimum and maximum feeding levels to be determined. Based on the calculations, the optimum feeding rate for sea bass fingerlings (3 g) reared in SW and FW is 3.0% and 3.5% bw day À 1 , respectively. In addition, the optimum feeding rate for FCE was calculated as 2.7% bw day À 1 in SW and 3.8% bw day À 1 in FW. It is concluded that 0044-8486/$ -see front matter D Aquaculture 231 (2004) 501 -515 growth and FCE of European sea bass can be improved by feeding them at about 3.0 -3.5% bw day À 1 in SW or FW. D

A trial was conducted to test the effect of partial replacement of fishmeal (Danish LT fishmeal—the only protein source in the control diet) by brewers yeast, in isonitrogenous (48% CP) and isoenergetic (22 MJ kg−1) diets for sea bass juveniles with an initial average weight of 12 g. Diets were formulated to include 0%, 10%, 20%, 30% or 50% of dietary N from yeast (diets D0, D10, D20, D30, D50, respectively); another diet supplemented with methionine (diet D50M) was also prepared.Each diet was distributed by hand to satiation to duplicate groups of 25 fish and the growth trial lasted 12 weeks. During the trial, feed intake (g kg−1 day−1) was identical in all groups. At the end of the trial growth rate was not significantly different among groups, except for the D50M diet, which was significantly lower than diet D30. Feed conversion was better for diets D10, D20 and D30, containing yeast than for the control diet. N retention (% N intake) was significantly higher in fish fed diets containing yeast (except for the D50M diet) than in those fed the control diet. There were no significant differences among groups in energy retention (% E intake). The protein content of the fish was significantly higher in fish fed diets containing yeast (except for the D50M diet) than in those fed the control diet.Apparent digestibility of the diets was determined in a separate trial with fish weighing 62 g. Feces collection was performed according to the Guelph system. Apparent digestibility coefficients of dry matter and energy significantly decreased with the increase of dietary yeast level. ADC of protein was significantly lower for the D50 diet than for the other diets.Results of this trial indicate that brewers yeast can replace 50% of fishmeal protein with no negative effects in fish performance. Moreover, the inclusion of up to 30% brewers yeast in the diet improved feed efficiency. There was no beneficial effect of supplementing the brewers yeast diets with methionine.

The immune response of European sea bass, Dicentrarchus labrax, to a natural infection by the copepod parasite Lernanthropus kroyeri was evaluated for the first time in vivo. The results clearly demonstrated the triggering of the fish immune system by the parasite. Lysozyme activity and alternative complement pathway were involved in the early action against the parasitical infection, whilst classical complement and respiratory burst (RB) activity took over in the later stages of infection. It was hypothesized that the levels of alternative and classical complement and RB stimulation indexes may determine the resistance capacity of the fish to the parasite. It is not clear how parasites can survive despite the strong immunological arsenal deployed by the fish. The continual increase of prevalence and severity of parasite infection suggested that the parasite’s mechanism of evasion of the immune system was extremely successful. The contrasting decrease in the negative effects of parasites on the fish health (such as gills anaemia) suggested that an equilibrium between the parasites and their hosts was reached in chronic infection. These dynamic interactions between parasites and fish hosts were probably the main determinant of host specificity.

From January to July 2011, a parasitical investigation was carried out on a selective sample of 10 Dicentrarchus labrax (Total Length 35 – 53 cm) from the Algerian western coast. Selective criteria concerned the freshness of the fishes, their sampling within the 12 hours following their gill-net catch, followed by an immediate dissection. We announce, for the first time in Algeria, the presence in Dicentrarchus labrax of 8 Helminth parasites; Diplectanum aequans, Serranicotyle labracis (Monogenea), Cainocreadium labracis, Bucephalus labracis, Bucephalus baeri, Bucephalus minimus (Digenea), larval stage of Tetraphyllidea (Cestoda) and larval stage L4 of Hysterothylacium aduncum (Nematoda) respectively with a prevalence of 20%, 10%, 90 %, 50%, 40%, 50%, 50% and 60%. The target of this investigation is to evaluate the parasitical threats towards the intensive sea farming of Dicentrarchus labrax in Algeria.

Aflatoxicosis and resulting epizootic hepatoma have been reported among a wide range of fish where Aspergillus species-contaminated foodstuffs are incorporated into the diet. Aflatoxin B 1 (AFB 1 ) is among the most potent known hepatotoxins and carcinogens. Therefore, it is an important potential toxicant to the most of the popularly cultured fish species. The present study was undertaken to assess the susceptibility and toxicity of AFB 1 to sea bass (Dicentrarchus labrax L.), by behavioral and biochemical evaluations. The estimated oral acute median lethal concentration (96 h LC 50 ) of AFB 1 for sea bass was 0.18 mg/kg bwt. The abnormal behavioral responses and signs of toxicity were described. The prolonged oral administration of 0.018 mg/kg bwt AFB 1 to sea bass for 42 successive days induced a significant increase in serum transaminases and alkaline phosphatase activities, and significant decrease in plasma proteins. Residual AFB 1 was detected at high levels (%5 ppb) in fish musculature at the end of the experimental period. We conclude that marine water sea bass is a species highly sensitive to AFB 1 . In addition, consumption of sea bass reared on AFB 1 -contaminated diet could have a negative health impact on human health.

An investigation was undertaken to study the effect of the synthetic androgen 17a-methyldehydrotestosterone on the sex reversal and gonadal development of the European sea bass Dicentrar-Ž . chus labrax L. A combination of three different hormonal doses 0.5, 3, 5 mgrkg food and three Ž . treatment durations 30, 60, 90 days was tested starting at 84 days post-hatching. Complete and permanent masculinisation occurred in 100% of individuals at all times. The range of treatments did not significantly compromise the gonadal development. However, testicular deformities were Ž . observed in low proportions less than 10% of both treated and control groups. q 1999 Elsevier Science B.V. All rights reserved. 0044-8486r99r$ -see front matter q 1999 Elsevier Science B.V. All rights reserved.

The purpose of this study was to develop a method for the hormonal masculinization of sea bass (Dicentrurchus 1ubru.x L.) reared under natural conditions of photoperiod and temperature. Sexually undifferentiated sea bass were fed 17a-methyltestosterone (MT) at 10 mg kg-' food during three distinct periods of 100 days each: Period I, 126-226 days post fertilization (DPF) (July-November) 8486/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI0044-8486(95)01030-O M. Bldzquez etal. /Aquaculture 135 (1995) 329-342

Feeding habits of young predatory fishes in marsh creeks situated along the salinity gradient of the Schelde estuary, Abstract Fish and macrobenthos were sampled in four different marshes along the salinity gradient of the Schelde estuary, Belgium/Netherlands, to investigate the importance of marsh creeks as foraging grounds for the dominant, larger fish species. The total density and biomass of all the main macrobenthic taxa (Corophium volutator, Nereis diversicolor, Oligochaeta, Macoma baltica and Heteromastus fliliformis) were measured. The feeding habits of the larger predatory fishes (Platichthys flesus, Dicentrarchus labrax) were investigated. Qualitative and quantitative stomach analyses included the calculation of different indices, showing the niche breadth (as diet diversity) and the niche overlap (as similarity between the predators' diet) for this habitat. These analyses showed that the two most important benthic prey species for P. flesus were C. volutator and N. diversicolor. D. labrax preyed upon a wider range of species, including C. volutator, N. diversicolor, Crangon crangon, Carcinus maenas and Orchestia spp. The stomach diversity of D. labrax and P. flesus showed differences between the marshes although there was no consistent pattern in diet composition, reflecting the opportunistic nature of feeding by these large predators. The fullness indices of both flounder and sea bass did not differ significantly along the salinity gradient and the estimated minimum consumption by these predators did not indicate a top-down control of the macrobenthic community. The salt marsh creeks seem to provide excess food for the visiting fish species. The benthic prey was present in very high abundances, which may suggest that the typical nursery species such as C. crangon and C. maenas, and early juveniles of P. flesus, D. labrax and Pomatoschistus microps were not preyed upon significantly. This supports the hypothesis that salt marsh creeks provide good refuge areas for nursery species against predation by larger fish.

The effects of different conditions of larval and postlarval rearing on the external morphology and internal anatomical characters were studied in juvenile and adult specimens of Dicentrarchus labrax L. (Teleostea, Moronidae) in order to assess the potential of a combined ...

Quality and shelf life of non-irradiated and irradiated (2.5 and 5 kGy) sea bass in ice conditions and stored at þ4 C were investigated by measurement in microbiological, chemical sensory analyses. Microbial counts for non-irradiated sea bass samples were higher than irradiated fish. Among chemical indicators of spoilage, total volatile base nitrogen (TVB-N) values increased to 36.44 mg/100 g for nonirradiated sea bass during iced storage, whereas for irradiated fish lower values of 25.26 mg/100 g and 23.61 mg/100 g were recorded at 2.5 and 5 kGy, respectively (day 17). Trimethylamine (TMA-N) values and thiobarbituric acid (TBA) values for irradiated samples were lower than that for non-irradiated samples. Acceptability scores for odour, taste and texture of cooked sea bass decreased with storage time. The sensory scores of sea bass stored in control and 2.5-5 kGy at þ4 C were 13 and 15 days, respectively. The results obtained from this study showed that the shelf life of sea bass stored in ice, as determined by overall acceptability of all data, is 13 days for nonirradiated sea bass and 15 days for 2.5 kGy irradiated and 17 days for 5 kGy irradiated sea bass. Published by Elsevier Ltd.