Comparative fatty acid composition of eggs from wild and captive black sea bass, Centropristis striata L.

Lipid content, lipid class and fatty acid compositions were determined in eggs from wild and captive black sea bass, Centropristis striata L., from northern (New England) and southern (South Carolina) regions to determine the effects of diet on egg composition and fertilization success. The formulated diets fed to the northern captive (NC) fish were higher in total lipids (22%) compared with the cut fish and squid diet fed to the southern fish (SC; 3.3% lipid) and had a higher relative amount of linoleic acid (LA) and lower relative amounts of docosahexaenoic acid (DHA) and arachidonic acid (AA). These dietary differences were broadly reflected in the egg lipid composition. The LA levels were higher in all lipid classes in eggs of NC fish while AA levels were lower. The DHA was higher in the major polar lipids (PL) (phosphatidylcholine and phosphatidylethanolamine) of SC eggs compared with NC. Compared with wild fish, both captive groups produced eggs with PLs richer in LA and lower in DHA and AA. Over all fish groups, fertilization success was directly correlated with levels of DHA and AA in the PLs and was inversely correlated with LA levels.     

Effect of dietary lipid level on juvenile black sea bass Centropristis striata fed two protein sources

A 10-week feeding trial was conducted with juvenile black sea bass Centropristis striata fed isonitrogenous diets (46% CP) with four lipid levels (7, 10, 13 and 16%) to identify dietary lipid levels supporting maximum weight gain and efficiency. Menhaden fish meal (FM) and animal protein concentrate (APC) were used in a 2×4 factorial experiment to evaluate effects of protein quality and lipid level on production. Weight gain, thermal growth coefficient, protein and energy retention, proximate composition and hepatic indices were evaluated. Weight gain was higher (P<0.05) in FM treatments and no protein sparing effect was observed. All growth, efficiency and retention parameters, except apparent net protein utilization (ANPU) among FM diets, were independent of dietary lipid. Based on proximate composition, diets should be restricted to no more than 13% lipid in 46% CP diet, and can be reduced to 7% without loss of growth and efficiency. Second order polynomial regressions on ANPU indicated 10–12% dietary lipid in a 46% CP diet is appropriate depending on protein quality. Reducing dietary lipid in current commercial feeds fed to black sea bass could represent a substantial cost savings in feed production.     

The effects of temperature on sex differentiation and growth of black sea bass (Centropristis striata L.)

To examine the effects of temperature on sex differentiation in the black sea bass ( Centropristis striata L.), a protogynous hermaphrodite, juveniles (∼0.5 g) were cultured in recirculating systems at 17, 21 or 25 °C. Growth was assessed at 155, 182, 241 and 275 days post hatch and sex differentiation was determined histologically. No differences were found in the sex ratios of fish reared at different temperatures, but only 55–64% developed as females. Growth was significantly greater in males across all temperature treatments. These results suggest that black sea bass exhibit sexually dimorphic growth patterns and that female-specific sex determination can be disrupted in culture.     

Influence of n-3 highly unsaturated fatty acid deficiency on the lipid composition of broodstock gilthead seabream (Sparus aurata L.) and on egg quality

A feeding experiment was conducted on gilthead seabream (Sparus aurata) broodstock to investigate the incidence of n-3 highly unsaturated fatty acids (n-3 HUFA) dietary deficiencies on the lipid composition of female liver, gonads and eggs, in relation to spawning quality. Broodstock were fed a control (C) diet or a n-3 HUFA deficient (D) but linolenic acid rich diet. After 20 weeks of feeding, the results showed that levels of total neutral (TNL) and total polar (TPL) lipids of female gonads and eggs were independent of diet. However the fatty acid composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) of female liver, gonads and eggs in the two groups of fish showed marked differences, reflecting the influence of fatty acid levels in the broodstock diets. This influence was even higher in TNL than in the phospholipid classes examined. In fish fed n-3 HUFA deficient diet, fatty acid composition of TNL of female gonads and eggs reflected the diet more than liver. A higher egg production in broodstock fed C diet (1.8% n-3 HUFA in diet) was extended to spawning quality such as percentages of fertilised and hatched eggs.     

Light intensity effects on early life stages of black sea bass, Centropristis striata (Linnaeus 1758)

The effects of four light intensities on growth and survival of first‐feeding stage black sea bass larvae Centropristis striata were investigated in a controlled‐environment laboratory. Fertilized eggs, obtained from LHRHa‐induced spawning of captive broodstock, were stocked (72 eggs L^?1) into twenty 15 L black tanks under light intensities of 100, 500, 1000 and 1500 lx, with five replicate tanks per treatment. The photoperiod was 12L:12D, the temperature was 20°C and the salinity was 35 g L^?1. Larvae were fed rotifers Brachionus rotundiformis from day 2 post‐hatching (d 2ph) at 5–10 rotifers mL^?1. Microalgae Nannochloropis oculata and Isochrysis sp. were added (1:1) daily to maintain a density of 300 000 cells mL^?1. Hatching success and larval growth and survival from d 2ph through d 15ph were monitored. Hatching success was 28–38% under all light intensities, and notochord length at hatching ranged from 2.8 to 3.0 mm, with no significant differences among treatments. By d 15ph, growth (mg wet weight) was significantly higher in the 1000 lx (0.914) and 1500 lx treatments (0.892) than in 100 lx (0.483), and a highly significant trend (P<0.01) towards increased survival with increasing light intensities was observed, from 1.3% at 100 lx to 13.9% at 1500 lx. Higher light intensities within the range of 100–1500 lx improved growth and survival of early larval black sea bass, suggesting that even higher light intensities may improve culture performance. This is consistent with conditions in shallow, near‐shore locations where eggs and larvae are distributed in nature.     

Production and storage of sperm from the black sea bass Centropristis striata L

Black sea bass Centropristis striata L. are protogynous hermaphrodites that develop and spawn as females before changing sex to male. Since all fish eventually become males, determining the relationship between sperm production, sperm quality and seasonal changes in plasma levels of testosterone (T) and 11‐ketotestosterone (11‐KT) could be useful for identifying appropriate males to maintain as broodstock. Milt and blood samples were collected three times during an 8‐week spawning season. Milt volume (3.5±0.76 mL kg^?1), sperm density (3.2 × 10⁸± 0.31 cells mL^?1), sperm production [11 × 10⁸±3.4 cells kg^?1 body weight (BW)] and sperm motility (80±0.6%) were at their highest during the first sampling interval and coincided with the highest 11‐KT levels (1.0± 0.11 ng mL^?1). All of the sperm indices decreased to their lowest levels during the final 3 weeks of the study. Sperm viability was highly correlated (adjusted R²=0.84) with sperm motility. Sperm cryopreserved in modified Mounib's extender (MME) had the highest post‐thaw motility compared with two other extenders. Post‐thaw motility of sperm cryopreserved in MME was not different from fresh after 90 days of storage. There was no difference in fertilization rates between fresh (69±2.4%) and post‐thaw (67±4.1%) sperm samples taken from the same male or among males. These results demonstrate that the quality of black sea bass spermatozoa is higher earlier in the spawning season and that acceptable post‐thaw fertilization rates can be obtained from cryopreserved sperm.     

Effects of dietary protein and lipid levels on growth performance and body composition of black sea bass Centropristis striata (Linnaeus 1758) during grow-out in a pilot-scale marine recirculating system

The influence of four formulated practical diets, with different protein and lipid levels, on the growth and body composition of black sea bass ( Centropristis striata L.) pre-adults was evaluated in a pilot-scale marine recirculating system. Four test diets were prepared with a combination of two protein levels (44% and 54%) and two lipid levels (10% and 15%). The diets were as follows: low protein and low lipid (LP:LL; 44:10), low protein and high lipid (LP:HL; 44:15), high protein and low lipid (HP:LL; 54:10) and high protein and high lipid (HP:HL; 54:15). Fish (mean weight=75.5 g) were fed the respective diets for 90 days. For fish fed LP:HL, body weight gain was significantly ( P <0.05) higher than fish fed LP:LL. Increasing the protein level from 44% to 54% did not produce a significant effect on weight gain at high lipid level. A significant ( P <0.01) interactive effect between dietary protein and lipid levels on the growth and feed utilization was observed. Total lipid content in the whole body, muscle and liver was significantly affected by the dietary lipid levels. The results suggested that a combination of 44% dietary protein and 15% lipid was optimal for the growth of black sea bass.     

Investigation of the temporal effects of spawning season and maternal and paternal differences on egg quality in Atlantic cod Gadus morhua L. broodstock

A better understanding of the parameters affecting egg quality and larval survival is of importance for continued development of cod broodstock and efficient husbandry practices. Decision tree analysis (DTA) was applied to analyse 3 years of egg quality data in an effort to extract the most important variables (i.e. predictors) in explaining differences in egg quality. The effect of three predictors (spawning time, maternal and paternal differences) has been studied on early cleavage pattern parameters, egg diameters, fertilization and hatching rates and has shown that females are the dominant variable and that time has a limited and inconsistent impact on the data. When using maternal, paternal differences and batch number (instead of spawning time) as predictors, the results confirm that no particular relationship is found between batch order (i.e. order in time) and egg quality. Moreover, batches with a higher egg quality show a consistency in the parameters assessed (i.e. batches with higher rates of normality in any parameter tend to be normal for other parameters). This is confirmed by the significant correlations found between cleavage parameters. Our results highlight that spawning time is of less importance than female parent contribution in ensuring high rates of fertilization and larval hatch, and maximizing general egg quality.     

Effect of lipid levels on the reproductive performance of Snakehead murrel,Channa striatus

Present study aimed to determine the optimum dietary lipid level in snakehead murrel channa striatus broodstocks. Triplicate groups of fish were fed for 240 days with isonitrogenous experimental diets with increasing lipid levels (100, 140, and 180 g kg^?1), using fish oil and soybean oil as the lipid sources with the ratio of (1:1). Weight gain, GSI, fecundity, oocyte diameter and number of mature oocyte were found to be significantly higher in the group fed with diet containing 180 g kg^?1 lipid level. Muscle fatty acid profile showed a significant increase in LA (18:2n‐6), LNA (18:3n3), total PUFA, n‐6 and ArA (20:4n‐6) in fish fed with diet containing 180 g kg^?1 lipid. Increasing lipid level up to 180 g kg^?1 resulted in significant increase in PUFA (LA & LNA), lc‐PUFA (EPA, DHA, ArA), total PUFA, n‐3 and n‐6 series in ovary and liver of female C. striatus.     

Effects of dietary n‐3 to n‐6 fatty acid ratios on spawning performance and larval quality in tongue sole Cynoglossus semilaevis

This study investigated the effect of n‐3 to n‐6 fatty acid ratios in broodstock diets on reproduction performance, fatty acid composition of eggs and gonads of tongue sole Cynoglossus semilaevis. Broodstock were fed five isonitrogenous and isoenergetic diets for 60 days. The supplemented lipids were prepared by a combination of fish oil and soybean oil inclusion FO (fish oil); FSO1 (fish oil: soybean oil = 7:1); FSO2 (fish oil: soybean oil = 2.2:1); FSO3 (fish oil: soybean oil = 1:1); FSO4 (fish oil: soybean oil = 1:4.3) as lipid sources with different n‐3 to n‐6 fatty acid ratios 10.40, 5.21, 2.81, 1.71 and 0.87. Results showed that relative fecundity, fertilization rate and survival rate of larvae at 7 days posthatching were all higher in broodstock fed FSO1 and FSO2 diet and significantly (P < 0.05) decreased in groups fed FSO3 and FSO4 diets. The best result in starvation tolerance test was obtained in FSO2 diet. The present study suggests that n‐3 and n‐6 PUFA ratio in broodstock diet has a considerable effect on spawning performance, egg and larval quality for C. semilaevis.     

Effects of dietary docosahexaenoic acid (22:6n‐3) and arachidonic acid (20:4n‐6) on the growth,survival, stress resistance and fatty acid composition in black sea bass Centropristis striata (Linnaeus 1758) larvae

The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from first feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and 10% total fatty acids=TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed significantly (P<0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also significantly (P<0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L⁻¹) challenge, no significant differences (P>0.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50=25.6 min) and larvae fed 0% DHA (ST50=18.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHA with increasing ARA within the range of 0–6% showed improved growth and survival from first feeding through metamorphic stages.     

Effects of shelter on growth and survival in age-0 black sea bass, Centropristis striata (L.)

Black sea bass Centropristis striata (L.) juveniles were reared in aquaria containing either shelter or no shelter to investigate the effects of shelter on growth and survival. The specific growth rates of juveniles were significantly higher in the sheltered aquaria. With shelter present, the average mortality of juveniles caused by agonistic behaviour was 44% compared with no mortality in the unsheltered aquaria. The results provide evidence that shelter is advantageous for growth, but not survival of black sea bass juveniles under culture conditions.     

The effects of dietary HUFA level on flame angelfish (Centropyge loriculus) spawning,egg quality and early larval characteristics

This study was conducted to determine the effects of dietary highly unsaturated fatty acids (HUFA) on flame angelfish (Centropyge loriculus) reproduction, and egg and larval quality. In the experiment, formulated diets containing 1.8, 2.9 or 3.6% n‐3 HUFA were fed to flame angelfish broodstock (n = 4) for 5 months. Mean fecundity (daily egg production), egg fertilization rates and embryo viability were used as indicators of egg quality. In addition, mean egg diameter, oil globule diameter, per cent hatch, larval size at hatch, per cent survival to yolk exhaustion and larval size at yolk exhaustion were recorded for each treatment. Flame angelfish fed the diet containing 3.6% n‐3 HUFA exhibited significantly increased fecundity, fertilization rates and embryo viability than fish that were fed the other two formulated diets. Egg diameter, egg oil globule diameter, larval size at hatch, larval survival to yolk exhaustion and larval size at yolk exhaustion from the 3.6% n‐3 HUFA broodstock treatment group were not significantly different from those derived from the Control broodstock treatment. These data revealed that flame angelfish egg quality could respond rapidly (within weeks) to maternal dietary changes. Results from this study further support that dietary HUFA composition can significantly affect broodstock reproductive performance as well as subsequent performance of eggs and larvae.     

Measures of egg quality in induced spawns of the Asian sea bass, Lates calcarifer Bloch

The egg morphometry and lipid and protein components were determined in induced spawns (n=14) of the sea bass, Lates calcarifer, to identify measures of egg quality. Based on fertilization and hatching rates, the spawns were classified either in Group I, (zero fertilization) or Group II (where fertilization and hatching occurred). The egg morphometry did not differ between the two groups (p > 0.05). The total lipid was higher in Group II than in Group I, although the difference was not significant (p > 0.05). The EPA and linoleic acid were significantly higher in Group II (p < 0.05). There were positive correlations between the total saturated fatty acids and fertilization rate (p < 0.05; r=0.58), the total saturated fatty acids and percentage of normal zygotes (p < 0.02; r=0.62), and DHA and the percentage of normal zygotes (p < 0.04; r=0.56). The total protein and FAAs were higher in Group I than in Group II, but the differences were not significant (p > 0.05). Proline, glycine, p-ethanolamine, and aspartic acid were significantly higher in Group II (p < 0.05), while tyrosine and glutamic acid were significantly higher in Group I (p < 0.05). Phosphoserine and fertilization rate were positively correlated (p < 0.03; r=0.60), as well as aspartic acid and hatching rate (p < 0.05; r=0.54). Arginine was negatively correlated with fertilization rate (p < 0.03; r=–0.61) and the percentage of normal zygotes (p < 0.03; r=–0.63). Serine was inversely correlated with yolk volume of the newly-hatched larvae (p < 0.03; r=–0.77). The moisture content of the eggs, which was significantly higher in Group II than in Group I (p < 0.03), was directly correlated with the FAAs:protein ratio (p < 0.03; r=0.76). The present results reveal egg components that may be used as quality measures in induced spawns of sea bass, a euryhaline teleost that spawn pelagic eggs containing an oil globule.     

Tolerance of juvenile black sea bass Centropristis striata to acute ammonia and nitrite exposure at various salinities

ABSTRACT:   Experiments were conducted to determine the acute tolerance of juvenile (mean weight ± standard error, 9.9 ± 0.9 g) black sea bass Centropristis striata to environmental un-ionized ammonia-nitrogen (NH₃-N) and nitrite-nitrogen (NO₂-N) exposure at various salinities. Specifically, median lethal concentrations (LC50 values) of NH₃-N and NO₂-N at 24, 48 and 96 h of exposure were determined at salinities of 10, 20 and 30 g/L at 22°C. With the exception of LC50 values determined at 48 h, median lethal concentrations of NH₃-N to black sea bass were not influenced by environmental salinity; 24, 48, and 96 h LC50 values ranged from 0.81 to 0.85, 0.65–0.77, and 0.46–0.54 mg-NH₃-N/L, respectively. In contrast, tolerance of black sea bass to environmental NO₂-N was compromised at reduced salinities. Median lethal concentrations of NO₂-N to fish at 24, 48 and 96 h of exposure ranged from 288.3 to 429.0, 258.4 to 358.8 and 190.0 to 241.9 mg-NO₂-N/L, respectively. Results indicate that while juvenile black sea bass are relatively sensitive to acute NH₃-N exposure, they are highly resistant to NO₂-N exposure.     

Effects of different diets and seawater systems on egg production and quality of the broodstock Babylonia areolata L. under hatchery conditions

The broodstock of spotted Babylon snail, Babylonia areolata, were conditioned in indoor tanks under two seawater systems (static system and flow‐through system) and five types of foods (fish, shrimp, squid, green mussel and formulated diet). High survival and good feeding was found from broodstock conditioned in all treatments of seawater systems and diets. All broodstock showed active behaviour with no signs of stress as exhibited by active movement and feeding, protrusion of siphonal tube and constant egg laying throughout the experiment. Two‐way analysis of variance showed that there were no significant differences (P>0.05) in the total yield of egg capsules, size of egg capsules, size of newly hatched larvae and growth of larvae among broodstock B. areolata conditioned in the seawater system and diet treatments, but there were significant differences (P>0.05) in the frequency of egg capsule laying, number of fertilized eggs/embryos per capsule, total yield of fertilized eggs/embryos and final survival of larvae among broodstock B. areolata conditioned in the diet treatments. We present initial evidence that the seawater system had a stronger influence on the egg production and quality of broodstock B. areolata than conditioning diets.     

Reproductive performance, lipids and fatty acids of mud crab Scylla serrata (Forsskål) fed dietary lipid levels

Natural food (NF, control), artificial diets (AD) containing total lipid levels of 10%, 12% and 14% (AD10, AD12 and AD14) and their combinations (AD10+NF, AD12+NF and AD14+NF) were fed for 112 days to pond‐sourced eyestalk‐ablated mud crab Scylla serrata (625±6.4 g) in tanks in order to determine their effects on reproduction and lipid profiles in broodstock tissues and zoeae. Crabs fed NF had the highest number of spawning followed by crabs fed AD10+NF and AD14+NF. Higher offspring production (number of zoeae) was obtained from crabs fed NF and AD+NF than from AD. As dietary total lipid levels increased, total lipid of broodstock ovaries, hepatopancreas, muscle and zoeae correspondingly increased in which AD+NF promoted higher levels than AD. Increased dietary total lipid levels enhanced lipid classes such as triacylglycerols and phosphatidyl choline levels in zoeae, all higher in crabs fed AD+NF than in AD. The major fatty acids in zoeae, particularly 16:0, 18:0, 18:1n‐9 and 20:4n‐6, 20:5n‐3 and 22:6n‐3, were higher in crabs fed AD+NF than in AD, the contents corresponding to broodstock dietary total lipid levels. A 10% total lipid in AD in combination with NF was sufficient to provide the essential lipids in crabs in the improvement of larval production and quality.     

Examination of broodstock diet effects on egg production and egg quality in flame angelfish (Centropyge loriculus)

This study was conducted to determine the effects of broodstock diet on flame angelfish (Centropyge loriculus) reproduction and generate baseline spawning performance (mean fecundity, egg fertilization, egg viability) and egg biochemistry data for this species. Sixteen flame angelfish broodstock pairs were maintained on one of three formulated diets or a raw diet (consisting of squid, shrimp, fish eggs and algae) to determine the effect of diet composition on the fecundity, egg fertilization rates and egg viability over a 7‐month period. Although all the diets supported similar mean spawn frequency and fecundity over the duration of the experiment, the mean fertilization rates and egg viability were significantly greater among pairs receiving the raw diet. Egg fatty acid composition was generally reflective of the maternal diet and similar to the values reported for other tropical species. In particular, dietary factors such as n‐3 highly unsaturated fatty acid and ARA level (which were elevated in the raw diet and eggs from fish receiving that treatment) are correlated with egg quality and are therefore worthy of future investigation. Because of the ease of conditioning, adaptability to varied formulated diets and continuous, sustained reproductive output, flame angelfish are an excellent model for examining the factors affecting marine fish egg and larval quality.     

Dispersal of black sea bass (Centropristis striata) larvae on the southeast U.S. continental shelf: results of a coupled vertical larval behavior – 3D circulation model

In the marine environment, pelagic dispersal is important for determining the distribution and abundance of populations, as well as providing connections among populations. Estimates of larval dispersal from spawning grounds are important to determining temporal and spatial patterns in recruitment that may have significant influences on the dynamics of the population. We present a case study of the dispersal of Centropristis striata (black sea bass) larvae on the southeast U.S. continental shelf. We use a coupled larval behavior – 3D circulation model to compare the effects of the timing and location of spawning against that of larval vertical migration on larval dispersal. Using the results of field data on larval vertical distributions, we compare the dispersal of virtual 'larvae' which have ontogenetic changes in vertical behavior with that of particles fixed near the surface and near the bottom. Larvae were released at potential spawning sites four times throughout the spawning season (February through May) for 3 yr (2002–04) and tracked for the assumed larval duration (from 27 to 37 days including the egg stage). Results indicate that adult behavior, in the form of spawning time and location, may be more important than larval vertical behavior in determining larval dispersal on the inner- and mid- continental shelves of this region.