A comparison of fatty acid composition and quality aspects of eggs and larvae from cultured and wild broodstock of common sole (Solea solea L.)

Eggs from a F₁ cultured broodstock of sole were compared with eggs from wild‐caught breeders throughout one spawning season, to evaluate if egg quality may be affected by culture‐related conditions. Fourteen batches of eggs from cultured broodstock and 17 batches from wild‐caught sole were compared with respect to fatty acid (FA) composition, egg size, fertilization rate and hatching rate. Based on a multivariate analysis of the FA profiles, it was possible to discriminate between culture and wild inheritance. Eggs from cultured broodstock had high levels of C20:1(n‐9), C18:2(n‐6) and C18:3(n‐3), whereas eggs from wild fish had high levels of C16:1(n‐7), C20:4(n‐6) and C20:5(n‐3). Differences in FA profiles were most likely related to dietary differences. Fertilization and hatching rates were generally low and lowest in eggs from cultured broodstock, but not related to FA composition. Larval growth of one batch from each group was compared. Larval growth was not correlated to broodstock origin, FA composition or egg or larval size. However, larval survival was significantly lower for larvae from cultured broodstock.     

Influence of broodstock gilthead seabream (Sparus aurata L.) dietary fatty acids on egg quality and egg fatty acid composition throughout the spawning season

The influence of broodstock dietary lipids on egg quality and egg fatty acid composition throughout the spawning season of gilthead seabream was investigated. For this purpose, the fish were fed for 7 months either a control diet (diet C) or a diet deficient in n−3 highly unsaturated fatty acids (n−3 HUFA) but rich in both oleic (18:1n−9) and linolenic (18:3n−3) acids (diet D). Eggs spawned by both groups of fish were sampled at the beginning, middle and end of the spawning season and the fatty acid composition of their neutral (NL) and polar lipids (PL) determined. In the early season, percentages of fertilized and hatched eggs, relative proportions of NL and PL as well as their fatty acid compositions, were not affected by the lipid composition of the broodstock diet. However, the eggs spawned during the middle and late seasons showed marked differences among the two groups of fish, clearly reflecting the influence of dietary fatty acids. This influence was more evident in the neutral lipid fraction than in the polar lipids. No correlation was found between the number of buoyant eggs and eicosapentaenoic (20:5n−3, EPA), docosahexaenoic (22:6n−3, DHA) fatty acids or total n−3 HUFA contents in egg phospholipids. However, a negative correlation was detected when percentages of fertilized eggs were compared with the levels of 18:1n−9, 18:3n−3 and with the ratio 18:1n−9/n−3 HUFA present in the phospholipids. Our results indicate the importance of maintaining not only the level of n−3 HUFA in egg membrane phospholipids, but also the balance between n−3 HUFA and other fatty acids such as 18:1n−9 and 18:3n−3, in order to obtain a high spawning quality.     

Energy content and chemical composition of gilthead seabream, Sparus aurata L., eggs

Abstract. Gross energy, ash content and elemental composition of carbon, nitrogen and hydrogen in eggs of the gilthead seabream, Sparus aurata L., have been determined throughout several spawning seasons. Also, changes in the biochemical components during embryonic development have been analysed. Gross energy of seabream eggs was approximately 1 J per egg. Dry weight of individual eggs at fertilization varied from 39 to 50μg, the chorion accounting for about 20% of total dry weight. However, there were no differences in carbon, nitrogen, hydrogen and ash percentages. From fertilization to hatching eggs lost 7·2% of total energy (chorion not included). The possible relationship between egg energy content and recent emerged larvae is discussed.     

Regulation of growth, fatty acid composition and delta 6 desaturase expression by dietary lipids in gilthead seabream larvae (Sparus aurata)

The Δ6 and Δ5 desaturases and elongases show only very limited activity in marine fish, and little is known of the possibility of enhancing Δ6 desaturase gene expression in these fish. The use of plant oils in marine fish diets is limited by their lack of n−3 highly unsaturated fatty acids (HUFA) despite an abundant content of the 18C fatty acid precursor linoleic and α-linolenic acids. The objective of the present study was to determine the ability of larval gilthead seabream to utilize vegetable oils and assess the nutritional regulation of Δ6 desaturase gene expression. Seventeen-day-old gilthead seabream larvae were fed during a 17-day period with one of four different microdiets formulated with either sardine fish oil (FO), soybean, rapeseed or linseed oils, respectively, or a fifth diet containing defatted squid meal and linseed oil. Good larval survival and growth, both in terms of total length and body weight, were obtained by feeding the larvae either rapeseed, soybean or linseed oils. The presence of vegetable oils in the diet increased the levels of 20:2n−9 and 20:2n−6, 18:2n−9, 18:3n−6, 20:3n−6 and 20:4n−6, in larvae fed rapeseed and soybean oils in comparison to those fed FO. In addition, a sixfold increase in the relative expression of Δ6 desaturase-like gene was found in larvae fed rapeseed and soybean oils, denoting the nutritional regulation of desaturase activity through its gene expression in this fish species. However, feeding linseed oil did not increase the expression of the Δ6 desaturase gene to such a high extent.     

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.     

Fatty acid composition of female and male clams (Ruditapes philippinarum): energy intake and temperature reliance

We analysed the effect of temperature, coupled with food ingestion rate (IR), on the fatty acid (FA) profile of female and male clams conditioned in two groups: L (low IR at 14 and 18 °C) and H (high IR at 18 and 22 °C). Significant differences for group L, both 18L and 14L with low IR and slow gonadal development, owed to differences in energy balance between 18L clams (negative energy balance) and 14L clams (positive energy balance). Plasmalogens (DMA 18:0) and non‐methylene‐interrupted FAs might protect against reactive oxygen species and preserve the integrity of the cell membranes during food stress in 18L clams. Differences in composition for group H, both 18H and 22H with high food intake, positive energetic balance and complete and similar gonadal occupation index (GOI), probably owed to the greater energy levels at 18 °C than at 22 °C. Clams at 22 °C H increased the oxidation of short‐chained PUFA 18:3ω3 and 18:3ω6 to maintain the same GOI as 18H clams. Regarding the sexual differences, the greater accumulation of 20:5ω3 and 20:4ω6 in females might be related with oocyte maturation and release during spawning, while the greatest levels of 22:6ω3 in males might be involved in spermatocyte membranes synthesis.     

Croissance et acides gras de la crevette Palaemon serratus (Crustacea,Decapoda) nourrie avec des aliments composés contenant différentes proportions d'acide linoleique et linolénique

Ten different compounded diets containing linoleic acid, C18: 2ω6 and linolenic acid, C18: 3ω3, in varying proportions, were fed to Palaemon serratus (Crustacea Decapoda) and the resultatn growth rates were measured. These results were then compared with those obtained from a compounded diet containing cod-liver-oil rich in long-chain poly-unsaturated fatty acids, C20: 5ω3 and C22: 6ω, and from natural food.Growth rates obtained with the cod-liver-oil and natural diets were in all cases superior to those obtained with diets containing linoleic and linolenic acid. The best growth rates from the latter diets were obtained when the C18: 2ω6/C18: 3ω3 ratio equalled 2.2. Compounded diets containing linoleic and linolenic acids in this proportion produced the lowest C20: 5ω3, C22: 6ω3, and C18: 3ω3 content in the specimens examined.Palaemon serratus would appear to be capable of synthesizing C20: 5ω3 and C22: 6ω3 from C18: 2ω6 and C18: 3ω3. Growth rates are improved when C20: 5ω3 and C22: 6ω3 are supplied directly in the diet.     

Effect of krill phospholipids versus soybean lecithin in microdiets for gilthead seabream (Sparus aurata) larvae on molecular markers of antioxidative metabolism and bone development

The objective of the present study was to compare the effectiveness of dietary marine phospholipids (MPL) obtained from krill and soybean lecithin (SBL) on the rearing performance and development of seabream (Sparus aurata) larvae. Larvae were fed from 16 to 44 day posthatching (dph) five formulated microdiets with three different levels (50, 70 and 90 g kg^–1) of phospholipids (PL) obtained either from an MPL or from a SBL source. Larvae‐fed MPL show a higher survival, stress resistance and growth than those‐fed SBL, regardless the dietary PL level. Overall, the increase in MPL up to 70 g kg^–1 total PL in diet was enough to improve larval gilthead seabream performance, whereas even the highest SBL inclusion level (90 g kg^–1 PL) was not able to provide a similar success in larval growth or survival. Inclusion of SBL markedly increased the peroxidation risk as denoted by the higher TBARs in larvae, as well as a higher expression of CAT, GPX and SOD genes. Moreover, SBL tends to produce larvae with a lower number of mineralized vertebrae and a lower expression of osteocalcin, osteopontin and BMP4 genes. Finally, increasing dietary MPL or SBL lead to a better assimilation of polyunsaturated fatty acids in the larvae, n‐3HUFA (especially 20:5n‐3) or n‐6 fatty acids (especially 18:2n‐6), respectively. In conclusion, MPL had a higher effectiveness in promoting survival, growth and skeletal mineralization of gilthead seabream larvae in comparison with SBL.     

Eggs of gilthead seabream Sparus aurata L. as a potential enrichment product of Brachionus sp. in the larval rearing of gilthead seabream Sparus aurata L.

The gilthead seabream Sparus aurata L. is a sequential spawner whose reproductive cycle can be manipulated to obtain year-round egg and fry production. Hence, there is an overproduction of eggs in commercial hatcheries that is normally wasted. Two feeding experiments were conducted with the purpose of investigating the potential use of fresh and freeze-dried gilthead seabream eggs for the enrichment of live preys. The first experiment was also designed to study the possibility of using freeze-drying as a conservation process for eggs in excess. Larvae were reared for 20 days after hatching (DAH),on a diet of Brachionus sp. As experimental controls, the commercial enrichment emulsion SUPER HUFA was used in the first experiment, and the microalgae Nannochloropsis sp. in the second. This study demonstrated the potential of gilthead seabream eggs as an enrichment product to be used in the feeding of the first larval stages of Sparus aurata L. The data obtained emphasize the need to have an overall perspective of the nutritional requirements of the organisms in culture.     

Reproductive performance of gilthead seabream (Sparus aurata L., 1758) fed two combined levels of carotenoids from paprika oleoresin and essential fatty acids

Despite carotenoids and essential fatty acids seem to play important roles in fish reproduction, no studies have yet been conducted to determine the effect of dietary carotenoids on gilthead seabream broodstock performance and their relation as antioxidants with dietary n‐3 highly unsaturated fatty acid (HUFA) levels. In addition, the high cost of synthetic sources of carotenoids is leading to the search for new natural carotenoid sources such as paprika oleoresin. Four experimental diets containing two combined levels of carotenoids from paprika oleoresin (40 and 60 mg kg^?1) and n‐3 HUFA (25 and 40 g kg^?1) were respectively fed to triplicate groups of gilthead seabream (Sparus aurata) broodfish. Elevation of n‐3 HUFA dietary levels from 25 to 40 g kg^?1 significantly improved gilthead seabream broodstock performance in terms of egg viability, hatching rates and fecundity. Besides, it markedly increased egg contents in HUFAs which play important energetic and structural roles and improve embryo development. Both arachidonic acid and eicosapentaenoic acid (20:5n‐3) egg contents were more readily affected by dietary n‐3 HUFA than docosahexaenoic acid. HUFA levels did not caused any negative effect suggesting an optimized content of antioxidants in broodstock diets. Increase in dietary carotenoids from 40 to 60 mg kg^?1 increased carotenoid contents in eggs and significantly improved egg fertilization rates suggesting an important sperm cell’s protective role by reducing the risk of lipid peroxidation which is detrimental for sperm motility. The increased inclusion of dietary paprika oleoresin enhanced egg carotenoid deposition and improved fish reproductive performance, denoting the high nutritional value of this product as a source of carotenoids for broodstock of this species.     

OPTIMAL SALINITY-TEMPERATURE COMBINATIONS FOR THE EARLY LIFE STAGES OF GILTHEAD BREAM,Sparus auratus L.

High larval mortalities during rearing of gilthead bream, Sparus auratus L., led to experiments on the influence of salinity and temperature on eggs and yolk-sac larvae. Test salinities ranged from 5 to 70 ppt for eggs and from 15 to 45 ppt for larvae; experimental temperatures were 18–20°C for eggs and 18, 23 and 26°C for larvae. Spawning conditions were 18–20°C and 33–35 ppt salinity; the yolk-sac larvae were chosen from hatches obtained under similar conditions (18°C and 35 ppt salinity). For eggs the optimum survival range was found to be 30–50 ppt at 18°C and 15–60 ppt at 23°C, while that for yolk-sac larvae was 15–25 ppt at all three temperatures. Choosing normal development (no dorsal curvature) as the decisive criterion, the optimum salinity range for egg incubation was reduced to 30–40 ppt at 18°C and to 35–45 ppt at 23°C, while that for the yolk-sac stage remained 15–25 ppt at all test temperatures. Egg incubation was most successful at salinity-temperature combinations close to those during spawning, whereas salinity had to be reduced by at least 10 ppt for yolk-sac larvae.     

GnRHa‐induced Multiple Spawns and Volition Spawning of Captive Spotted Rose Snapper,Lutjanus guttatus,at Mazatlan,Mexico

Sexual maturation and induced spawning treatments were carried out with captive spotted rose snapper, Lutjanus guttatus. A total of 3013 × 10⁶ eggs (64.7% were floating) were produced from eight treated females in 42 spawns induced with GnRHa implants during the course of the present study. GnRHa ethylene‐vinyl acetate copolymer effective doses were 204 ± 11 µg/kg in June 2005, and 224 ± 13 µg/kg in July 2005. General fertilization was 50.9 ± 34.5% and 12–14 h after spawning, viability of floating eggs was 90.4 ± 12.4%. Mean incubation period at 29–31 C was 18–20 h, and mean hatching was 94.4 ± 8.2% (73–100%). Newly hatched larvae were 2.18 ± 0.15 mm in total length (TL). One month after the last hormone experiment, previously GnRHa‐treated and untreated fish began spawning voluntarily. Hormone‐treated breeders had higher fecundity than untreated fish, producing 72.5 million eggs versus 13.9 million eggs for the untreated fish, over the following 11 mo. Combined data of volitional spawning for total egg fertilization, viability, hatching, and larval TL were 77.7 ± 1.8%, 90.3 ± 1.3%, 87.9 ± 2%, and 2.50 ± 0.12 mm, respectively. These results can ensure the sustainability of a commercial hatchery.     

Nutritional stimuli of gilthead seabream (Sparus aurata) larvae by dietary fatty acids: effects on larval performance,gene expression and neurogenesis

The concept of nutritional programming raises the interesting possibility of directing specific metabolic pathways or functions in juvenile fish, for example, to improve the use of substitutes to fishmeal and oil, and hence to promote sustainability in aquaculture. The aim of the study was to determine effects of early nutritional stimuli of gilthead seabream larvae and check if nutritional programming of gilthead sea bream is possible between 16 days post hatching (dph) and 26 dph. A trial was conducted to determine the effects of early nutritional stimuli of gilthead seabream larvae. Five experimental microdiets (pellet size <250 μm) were formulated containing five different proportions of a marine lipid source rich in long‐chain polyunsaturated fatty acids (LC‐PUFA) and two vegetable lipid sources rich in linolenic and linoleic acids. The results of this study demonstrate that dietary n‐3 LC‐PUFA levels increased larval growth and survival affecting Δ6 desaturase gen (fads2) expression and retinal neurons density. However, the high mortalities obtained along on‐growing in fish fed low n‐3 LC‐PUFA at 16 dph constrained the feasibility of nutritional programming of gilthead seabream during this late developmental window and needs to be further investigated.     

Efficacy of dietary methyl esters of n−3 HUFA vs. triacylglycerols of n−3 HUFA by gilthead seabream (Sparus aurata L.) juveniles

A feeding experiment was carried out on gilthead seabream juveniles to investigate the utilization of dietary n−3 highly unsaturated fatty acids (n−3 HUFA), when presented as methyl esters or as triacylglycerols. Three groups of gilthead seabream juveniles, of an initial mean weight of 62 g, were fed diets containing the same level of n−3 HUFA (about 2% dry weight basis, DWB) but where these essential fatty acids (EFA) were supplied in the form of methyl esters, triacylglycerols or as a mixture of these two chemical forms (diets 1, 2 and 3, respectively). A fourth group of 62-g individuals was fed a diet containing a particularly high level of triacylglycerols of n−3 HUFA (about 5% DWB). After 8 weeks of feeding, the results showed that fish growth, hepatosomatic index, total lipid content, and fatty acid composition of neutral and polar lipids of brain, liver, gills and muscle were not affected by the chemical form of the lipids given in the diet. However, individuals fed the very high level of EFA (diet 4) showed a lower growth rate than the other three groups of fish. In addition, eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3) levels in both neutral and polar lipids from liver, gills and muscle were higher in this group of fish, with the brain fatty acid composition being less affected by dietary regime.     

Resting Egg Production and Fatty Acid Enhancement in the Waterflea,Ceriodaphnia quadrangula,by Using Combination of Light Regime and Food

Combined effects of different light regimes, 6L:6D and 12L:12D (hours light : hours dark, L:D) and algal foods of Scenedesmus quadricauda (S) and Chlorella vulgaris (C) on ephippia production and fatty acid (FA) profile of Ceriodaphnia quadrangula were investigated. The highest resting egg production, density, and specific growth rate were obtained with 6L:6D+S; followed by 12L:12D+S treatment. The C16:0 varied from 16.2 to 22.16 mg/g dry weight (d.w.); C18:1n?9 from 11.03 to 14.94 mg/g d.w; C18:2n?6 from 9.79 to 20.24 mg/g d.w; and C18:3n?3 from 6.98 to 16.02 mg/g d.w. The amounts of C20:4n?6 (4.36 mg/g d.w) and C20:5n?3 (3.35 mg/g d.w) at 6L:6D+S were highest compared to other treatments. The maximum saturated fatty acids and monounsaturated fatty acids were obtained at 6L:6D+C while maximum polyunsaturated fatty acids observed at 6L:6D+S and 12L:12D+C. The resting egg production and FAs profile could be improved when the frequency of changes from light to dark were increased. Our findings also indicate a significant increase in the quantity of C18:3n?3 in C. quadrangula populations during resting egg formation, hence, implying that manipulation of light regime and algal food can improve performance of C. quadrangula as a live food in aquaculture industries, especially for larval feeding.     

Biochemical composition and quality of turbot (Scophthalmus maximus) eggs throughout the reproductive season

The present study investigated the biochemical composition and quality of turbot (Scophthalmus maximus) eggs throughout the reproductive season. Results showed that the fertilization, hatching and egg floating rates were variable throughout the reproductive season, with the highest values recorded during the mid-season. Meanwhile, positive correlations were found between fertilization, hatching rate and floating rate. The composition of turbot eggs, including total lipid, protein, carbohydrate, moisture and dry weight showed no significant differences during the reproductive season. Furthermore, no correlations were found between egg compositions and viability parameters (VPs), including fertilization and hatching rates as well as larval deformity rate. However, egg diameter varied and correlated with fertilization, hatching and egg floating rates. The fatty acid in eggs at mid-season had significantly higher levels of C14:0, C16:0, C16:1n-7, C18:0, C18:1, C20:4n-6, C20:5n-3 and C22:6n-3. Moreover, significant relationships were found between fatty acids and VPs. Eggs of the middle season had significantly higher concentration of isoleucine, leucine, lysine, methionine, valine, alanine, aspartate, glutamate and serine, whereas no significant relationships were found between amino acids and VPs. These observations suggest that the biochemical profile of eggs may be useful in evaluating egg quality and improving broodstock management for turbot.     

Fish oil replacement by different microalgal products in microdiets for early weaning of gilthead sea bream (Sparus aurata,L.)

The aim of this study was to determine if algal products rich in DHA or ARA are able to completely replace fish oil in microdiets for marine fish larvae, gilthead seabream and if extra supplementation with EPA may further enhance larval performance. For that purpose, 20 day‐old gilthead seabream larvae of 5.97 ± 0.4 mm mean total length and 0.12 ± 0.001 mg mean dry body weight were fed with five microdiets tested by triplicate: a control diet based on sardine oil; a diet containing AquaGrow^® DHA (diet DHA) to completely substitute the sardine oil; a diet containing AquaGrow^® ARA (diet ARA); a diet containing both products, AquaGrow^® DHA and AquaGrow^® ARA to completely substitute the fish oil; and, a diet containing both products, AquaGrow^® DHA and AquaGrow^® ARA, together with an EPA source. Temperature, air and salinity activity tests were also performed to detect larval resistance to stress. At the end of the experiment, final survivals did not differ among groups. The microorganism produced DHA was able to completely replace fish oil in weaning diets for gilthead seabream without affecting survival, growth or stress resistance, whereas the inclusion of microorganism produced ARA did not improve larval performance. Moreover, addition of EPA to diets with total replacement of fish oil by microorganism produced DHA and ARA, significantly improved growth in terms of body weight and total length. The results of this study denoted the good nutritional value of microorganisms produced DHA as a replacement of fish oil in weaning diets for gilthead seabream, without a complementary addition of ARA. However, dietary supplementation of EPA seems to be necessary to further promote larval performance.     

Effect of dietary marine lipids on female white bass ova compositions and progeny survival

We evaluated white bass ovum fatty acid composition as well as embryonic and larval survival after varying n-3 and n-6 long-chain polyunsaturated fatty acid (LC-PUFA) concentrations in maternal diets. Diets containing graded levels (0, 33, 66, or 100%) of squid to menhaden oils were fed daily to apparent satiation to female white bass for 8 weeks prior to spawning. Embryonic survival was negatively related to maternal squid oil intake (P = 0.015, R ² = 0.970). Squid oil-fed broodstock produced ova with decreased 20:5n-3 and increased C₁₈ polyunsaturated fatty acid concentrations, largely reflecting the fatty acid profile of squid oil. Within ovum phospholipid, accumulation of 18:2n-6 may have altered biological function resulting in the lower embryonic survival among ova produced from the squid oil-fed broodstock. Our data suggest the importance of feeding white bass broodstock diets high in total n-3 LC-PUFA (at least 4.0% dry matter), and 20:5n-3-rich lipid sources such as menhaden oil can be effectively utilized by female white bass to produce quality ova.     

Reproductive development, GnRHa-induced spawning and egg quality of wild meagre (Argyrosomus regius) acclimatised to captivity

The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight?=?20?±?7?kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550?μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20?μg?kg(-1) for females and 10?μg?kg(-1) for males) or a slow-release implant loaded with the same GnRHa (50?μg?kg(-1) for females and 25?μg?kg(-1) for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs?kg(-1) and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs?kg(-1). In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs?kg(-1). The latency period was 48-72?h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70?±?0.3% and 0.99?±?0.02?mm, respectively, for GnRHa-implanted fish and were significantly higher (P?相似文献   

Biochemical composition and quality of captive-spawned cobia Rachycentron canadum eggs

Interest in the commercial production of cobia Rachycentron canadum continues to rise as additional insight is gained into the hardy and fast growing nature of this species. However, research regarding the biochemical composition of captive-spawned eggs and egg and larval quality remains scarce. Such data is essential as a common bottleneck to production is a steady supply of fingerlings for grow-out. This study quantified the biochemical composition and quality of cobia eggs produced over 2 spawning seasons by broodstock on a traditional ‘trash fish’ diet which is commonly fed to tank spawning cobia. Throughout the study, batch fecundity, proportion of floating eggs and percent hatch averaged > 1 million eggs,  0.8 and 70%, respectively. Batch fecundity was significantly higher during the second spawning season as a result of the increased size of the females which weighed 18/22 kg and 22/26 kg at the beginning of each season. A positive correlation was found between the proportion of floating eggs and hatch rate for both spawning seasons. No correlations were found between egg composition (total lipid (30.0 ± 1.1% dry wt), protein (25.4 ± 2.2% dry wt), carbohydrate (2.4 ± 0.3% dry wt), vitamin E (10.2 ± 0.6 μg/g wet wt) or dry weight (119.1 ± 5.5 μg/egg)) and egg quality (proportion of floating eggs, hatch rate, larval growth and larval survival). Further, no differences in egg composition were noted between seasons or over the course of each season. The fatty acid composition of cobia eggs varied between seasons possibly due to changes in the quality of frozen feed (fish, shrimp, squid) given to the broodstock. The only correlation between the fatty acid profile and egg quality was a decrease in the proportion of floating eggs as the total amount of n-3 highly unsaturated fatty acids increased. No relationship between egg quality and amino acid content was noted with the most prominent amino acids being glutamate, leucine, alanine, proline, lysine and aspartate nor were any differences detected between spawning seasons.