EFFECTS OF SOME TECHNICAL FACTORS ON REPRODUCTIVE PERFORMANCES AND RESULTED SEED PRODUCTION OF SNUBNOSE POMPANO (trachinotus blochii lacepede, 1801) IN KHANH HOA

MINISTRY OF EDUCATION AND TRAINING NHA TRANG UNIVERSITY oo0oo - NGO VAN MANH EFFECTS OF SOME TECHNICAL FACTORS ON REPRODUCTIVE PERFORMANCES AND RESULTED SEED PRODUCTION OF SNUBNOSE POMPANO (Trachinotus blochii Lacepede, 1801) IN KHANH HOA Major code: Aquaculture Code: 62620301 SUMMARY OF DOCTORAL THESIS KHANH HOA – 2015 Research was accomplished at Nha Trang University Supervisors: Associate Prof PhD Lai Van Hung PhD Ngo Anh Tuan Referee 1: Associate Prof PhD Do Van Khuong Hai Phong Research Institute for Marine Fisheries Referee 2: PhD Truong Ha Phuong Research Institute for Aquaculture No Referee 3: PhD Huynh Minh Sang Institute of Oceanography The thesis was defended at the committee of doctorate thesis examiners of Aquaculture Institute in Nha Trang University at …… , ………, ……… 2015 The thesis can be found at: National Library of Vietnam The Library of Nha Trang University INTRODUCTION The snubnose pompano (Trachinotus blochii) is a pelagic fish and able to tolerate a wide range of salinities It has become an important marine fish at many countries in Asian Pacific Ocean due to high market price, available culture techniques Many studies had been conducted on reproduction and grow-out culture of this species However, the current problems relating to the low maturity, low fertilized and hatching rates as well as fluctuated survival rate and high deformity of early larvae has not been paid adequate attentions Many studies have indicated the influence of egg and larval quality on seed production This may be attributed by aspects of the broodstock nutrition The diets containing available n-3 HUFA, vitamin E and astaxanthin play important roles in gonadal development and quality In addition, the applications of new technical advances in fish reproduction including feeding regime, stocking density, nutrient supplementation as well as photoperiod to enhance the efficiency of rearing efficiency also evaluated in some marine fish species such as European sea bass, barramundi Therefore, it is important to continuously solve the current problems to improve reproductive effeciency of snubnose pompano Acording to these reasons, the thesis “Effects of some technical factors on reproductive performances and resulted seed production of snubnose pompano (Trachinotus blochii Lacepede, 1801) in Khanh Hoa » was conducted Objectives: - General objective: Provide new techniques in reproduction of snubnose pompano - Particular objective: Improve the fecundity, egg and larval quality as well as juvenile rearing efficiency The main contents: Effects of different trash fish, feeding rations and vitamin E levels fed to snubnose pompano broodstocks on reproductive efficiency in terms of fecundity, egg and larval quality Effects of different hormones injected to broodstocks on fecundity, egg and larval quality of snubnose pompano Efficiency of technical solutions applied in larval and juvenile rearing of snubnose pompano The significances: - Scientific significance: This research contributes to the understanding in reproduction and seed production - Practical significance: The results of the research provide suitable techniques in snubnose pompano reproduction The application of these protocols can improve survival rate and growth performance of snubnose pompano in hatcheries Consequently, it also introduces new species for marine finfish aquaculture in Vietnam Findings - This is the first publication in nutritial requirement for broodstocks of snubnose pompano in Vietnam The study has determined the suitable diets, optimum feeding ration and vitamin E for broodstocks of snubnose pompano The suitable hormones and dose also have been determined to optimize the reproductive performances of snubnose pompano The new technical solutions in thee present study including stocking density, feeding ration, photoperiod and optimum DHA Protein Selcon enriched concentration are firstly applied to improve the survival, growth performances of snubnose pompano in Vietnam CHAPTER – LITERATURE REVIEW 1.1 Overview of marine fish culture in the world and Vietnam In 2010, the total production marine fish culture in both marine and brackish water was 4,429,000 tons, accounting for 19,3% of total production of aquaculture The average annual growth rate for brackishwater fish and marine fish aquaculture production from 1990 to 2010 was 9,3% The major cultured species were Atlantic salmon, snapper, European seabass, red drum, milkfish, grouper, barramundi, red seabream, mullet, turbot, cobia, cod and tuna, in which salmon aquaculture production was 1.9 00.000 tons The main producers were China, Norway, Chile, Japan, Greece, Turkey, Taiwan-China, Philippine, Indonesia and Vietnam The marine fish aquaculture in Vietnam started in 1990s in small-scales systems including cages and earthern ponds in coastal provinces such as Quang Ninh, Hai Phong, Nghe An and Khanh Hoa, in which grouper, barramundi and cobia and red snapper were the major cultured species Although, the successful reproductions of some marine finfish have been developed, the limitation of seed supply still has not met the seed demand for marine aquaculture The reproduction of snubnose pompano was first developed in Taiwan in 1989, and then China, Indonesia and Vietnam also achieved the success in reproduction of this species 1.2 Biology of snubnose pompano Snubnose pompano (Trachinotus blochii Lacepede, 1801) is belong to Carangidae family, the order Perciformes It mainly distributes in Pacific Ocean, Atlantic Ocean and Indian Ocean Snubnose pompano is omnivores, but mostly feed aquatic animals with active feeding Snubnose pompano has fast growth rate Juvenile (19 – 26 g) can grow to 608 – 610 g after months The breeding season of snubnose pompano was from March to October, and independent with the fullmoon The fecundity of this species ranges from 38.000 – 122.000 eggs/kg female 1.3 The maturity and spawning of teleost fish The reproductive biology varied in fish species to adapt to the environmental conditions For example, the Pacific salmon only spawn once before death, while many other species can spawn many times during their life Many species usually build nests for spawning and egg protection, while the changes in reproductive characteristics including increase in fecundity, reproduce several times per year are observed in unprotected egg species The available foods and environmental conditions play important roles in fish reproduction Fish can perceive and utilize seasonal variations in environmental factors such as photoperiod, temperature, moon phase, water flowing and water pressure to ensure reproductive success during suitable periods of the year The breeding cycle is controlled by hormones produced from pituitary gland and gonad, in which gonadotropic hormone (GTH), follicle- stimulating hormone (FSH) and luteinizing hormone (LH) play important roles 1.4 The overview on nutrional requirements of broodstock and young juvniles The broodstock nutrition management plays important role in improvement the quality of eggs and larvae, determining the success of marine fish reproduction The available foods with good quality play crucial roles in survival and development of larvae Thus, the understanding in nutritional requirement, digestive development and suitable feeding regimes is particularly important in the development of early larvae 1.5 The effects of induced hormone on reproductive performance of fish The determination of hormone injections or adjusting the ecological factors changes in each fish, depending on the reproductive biology, maturity Currently, there are several types of hormones including LHRHa, ovaprim, pituitary gland, HCG, PMS used in fish reproduction with different advantages and disadvantages effects Many studies has evaluated the effects of hormones on the fecundity, time to spawn of broodstocks, while the knowledge on the reproductive cycles, the quality of egg and larvae affected by hormones is still unknown 1.6 The effects of stocking density, diets and photoperiod on growth performances of young juveniles In juvenile stage, the high stocking density may leads in the competition for food and living space, resulting in low survival and high coefficient variation Besides, other factors such as diet, water- flow, color tanks, light and diseases also affect the growth, survival and feeding behavior of juveniles CHAPTER MATERIALS AND METHODS 2.1 Species, time and location of research - Species: Snubnose pompano (Trachinotus blochii Lacepede, 1801) - Duration: June 2009 – June 2013 - Location: All experiments for broodstocks were conducted in Marine fish aquaculture station, located in Nha Trang bay, Khanh Hoa, whereas the trials for larvae and juvenile were carried out in Duong De marine seed production hatchery in Nha Trang, Khanh Hoa 2 Contents Evaluating the effects of technical solutions on eggs, larvae quality and juvenile rearing efficiency of snubnose pompano in Khanh Hoa province Effects of different trash fish, feeding rations and vitamin E levels fed to broodstocks on fecundity, egg and larval quality of snubnose pompano Effects of different hormones injected to broodstocks on fecundity, egg and larval quality of snubnose pompano Evaluated parameters: - Reproductive performance (maturity, fecundity) - Thời gian tái phát dục, thời gian hiệu ứng thuốc - Egg quality (Egg diameter, ferlilized rate and hatching rate) - Larval quality (larval size, deformity, survival rate) Evaluating some technical solutions on improvement of seed production From larvae to fry - Effects of the stocking density - Effects of live feed with DHA Protein Selco enrichment - Effects of weaning time to micro diets - Effects of the photoperiod From fry to juvenile - Effects of the stocking density - Effects of the feeding rations - Effects of the photoperiod and feeding frequency Evaluations and conclusions Figure 2.1: Diagram of the research 2.3 Materials and methods 2.3.1 Broodstock Broodstocks used in this study were selected from grow-out cages, at average weight of 2,2 – 3,7 kg The first trial: Effects of different trash fish diets for broodstock on egg and larval quality of snubnose pompano Broodstock were stocked in cages (21fish/cage) and fed different diets including 100% fish (NT1); 70% fish: 15% squid: 15% shrimp (NT2); 70% fish: 30% squid (NT3) and 70% fish: 30% shrimp (NT4) All diets were sampled for proximate composition and fatty acids analysis before feeding experiment commenced The fecundity, egg diameter, floated egg, fatty acid profile in egg, fertilized, hatching rate, larval size, deformity and survival rate of larvae three day after hatching were evaluated to determine the suitable diet for broodstocks The second trial: Effects of feeding ration fed for broodstocks on reproductive performances of snubnose pompano Based on the results in the first trial, the broodstocks in this experiment were fed diet containing at feeding ratios: 5% (NT1); 7% (NT2); 9% (NT3) and 11% (NT4) The broodstock, cages, stocking density were similar as descriptions in the first trial The fecundity, egg diameter, floated egg rate, fatty acid profile in egg, fertilized rate, hatching rate, larval size, deformity and survival rate of larvae three day after hatching were evaluated to determine the suitable feeding ration for broodstocks The third trial: Effects of vitamin E supplementation in diet fed for broodstocks on reproductive performances of snubnose pompano In this trial, all broodstocks were fed with levels of vitamin E supplementing: mg/kg (NT1); 250 mg/kg (NT2); 500 mg/kg (NT3); 750 mg/kg (NT4) and 1.000 mg/kg (NT5) The feeding ration was % body weight based on results of the second trial The broodstock, cages, stocking density were similar as descriptions in the first trial The fecundity, egg diameter, floated egg rate, fatty acid profile in egg, fertilized rate, hatching rate, larval size, deformity and survival rate of larvae three day after hatching were evaluated to determine the optimum dietary vitamin E for broodstocks The fourth trial: Effects of induced hormones on reproductive performances of snubnose pompano Broodstocks were fed diet containing 70% fish: 15% squid and 15% shrimp with 750 mg/kg vitamin E supplementing at feeding ration of 9% body weight Broodstocks were injected different hormones including 50 µg LRHa + mg DOM/kg (NT1); 1200 IU HCG/kg (NT2); 500 IU HCG + 40 µg LRHa/kg (NT3); Common carp pituitary of 10 mg/kg (NT4) and saline water at 0,5 mL/kg (NT5) The fecundity, egg diameter, floated egg rate, fertilized rate, hatching rate, larval size, deformity and survival rate of larvae three day after hatching were evaluated to determine the suitable hormone for reproduction The broodstock, cages, stocking density were similar as descriptions in the first trial 2.3.3 Methods used in 3rd content 2.3.3.1 Larvae Fertilized eggs were obtained from reproduction in Vung Ngan station, and then tranferred to Duong De marine seed production hatchery for incubation Newly hatching larvae were selected and used for experiments The fifth trial: Effects of stocking densisty on growth, survival and deformity of snubnose pompano larvae Satge 1: From newly hatched larvae to 23rd days old The larvae were randomly distributed to twelve 100-L fiber-glass tanks with stocking densities including 15, 30, 45 and 60 larvae/L Each experimental density was assigned to three randomly positioned tanks The survival rate, growth rate, deformity of larvae were evaluatetd after 23 days of experimental period Stage 2: From fry to juvenile The fry ( average length 19,22 ± 1,63 mm and weight 0,42 ± 0,03g) were selected from previous trials and randomly distributed to twenty four 70-L fiber-glass tanks with stocking densities including: 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0 and 4,5 inds/L Each experimental density was assigned to three randomly positioned tanks The survival rate, growth rate, deformity and feed conversion ratio were evaluatetd after 28 days of experimental period The sixth trial: Effects of DHA Protein Selco levels in live feed on growth performances and shock resistance of snubnose pompano larvae The larvae were randomly distributed to thirty two 100-L fiber-glass tanks at the stocking density of 40 larvae per tank Fish was fed live feed contained DHA Protein Selco enrichment with concentrations: 0, 50, 100, 150, 200, 250, 300 and 350 ppm The survival rate, growth rate, deformity and shock resistance to temperature and salinity shocks were evaluatetd after 33 days of the feding period Whereas the resistance to mechanical shock was evaluated after 23 and 33 days of the feeding period The seventh trial: Effects of weaning time to commercial diet on growth performances and survival of snubnose pompano fry The newly hatching larvae were cultured in m3 tanks for 12 days and then fish (average length 4,45 ± 0,81 mm and weight 2,71 ± 0,29 mg) were randomly distributed to twenty-one 70-L fiber-glass tanks at the stocking density of ind/L Fish was fed a commercial diet (NRD, INVE, Thailand) at different weaning times including 13, 15, 17, 19, 21, 23, 25 days after hatching Each treatment was assigned to three tanks and lasted for 20 days The eighth trial: Effects of feeding rations on growth performances and survival of juvenile snubnose pompano Juveniles (35 days after hatching) had average length 19,76 ± 1,23 mm and weight 0,35 ± 0,04 g were randomly distributed to fifteen 70-L fiber-glass tanks at the stocking density of inds/L Fish was fed commercial diet (NRD, INVE, Thailand) with feeding rations including 3, 6, 9, 12 and 15 % wet body weight Each treatment was assigned to three tanks The survival rate, growth rate, deformity and feed conversion ratio were evaluatetd after 28 days of experimental period The nineth trial: Effects of photoperiods on growth performances and survival of snubnose pompano larvae The larvae were randomly distributed to twelve 100-L fiber-glass tanks at stocking density of 40 inds/L The tank was controled with photoperiod regimes including natural photoperiod hours/day – 8L:16D (NT1); 12L:12D (NT2); 18L:6D (NT3) and 24L:0D (NT4) Each treatment was assigned to three tanks The survival rate, growth rate, deformity were evaluatetd after 25 days of experimental period The tenth trial: Effects of photoperiod and feeding frequency on growth performances and survival of juvenile snubnose pompano Juveniles (average length 12,15 ± 1,14 mm and weight 0,12 ± 0,01 g) were randomly distributed to twenty-four 70-L fiber-glass tanks Fish was fed feeding rations (2, 4, 6, times/day) with photoperiod regimes (12 and 18 hours) Each treatment was assigned to three tanks The survival rate, growth rate, deformity and feed conversion ratio were evaluatetd after 28 days of experimental period 2.4 Parameter calculations 2.4.1 Water quality paramenters 2.4.2 Reproductive characteristics 2.4.3 Growth performances in terms of growth rate, survival, deformity and feed conversion ratio 2.4.4 Proximate composition 2.5 Statistical analysis All data were expressed as mean ± SE and analysed by one-way analysis of variance (ANOVA) with post hoc Duncan multiple comparison tests by using SPSS for Windows version 12.0 to evaluate the significant differences among treatments Two-way analysis ANOVA with Duncan post hoc test was used to analyse the effects of different factors and interaction in two factor experiments The statistical significance was evaluated at P < 0.05 All charts were drawed using Microsoft Excel CHAPTER 3: RESULTS AND DISCUSSIONS 3.1 Effects of different trash fish, feeding rations and vitamin E levels fed to broodstocks on fecundity, egg and larval quality of snubnose pompano 3.1.1 Effects of different trash fish diets for broodstock on egg and larval quality of snubnose pompano 3.1.2.1 Maturity and fecundity Broodstocks fed different diets showed significantly effects on the maturiry (P < 0.05) The lowest maturity was observed in fish fed CT diet, while the highest maturity was recorded in fish fed diet containing 70% fish: 15% squid and 15% shrimp Different diets also significantly affected (P < 0.05) on the fecundity of snubnose pompano, where the highest fecundity was reported in broodstocks fed diet containing raw fish, squid and shrimp Although, the fecundity of fish fed raw fish with squid supplementing showed the significantly higher than those of fish fed only raw fish diet, it still was significantly lower than the fecundity of fish fed diet containing raw fish and squid and shrimp supplementation 3.1.2.2 Egg quality Crude lipid and fatty acid profile There were no effects (P > 0.05) of different diets fed to broodstocks on the lipid content, saturated fatty acid and mono unsaturated fatty acid profiles in egg of snubnose pompano, where crude lipid ranged from 11,65 – 12,63% in dry weight basic, saturated fatty acids was from 1,42 to 1,77%, and mono unsaturated fatty acids were 1,31 to 1,68% The PUFA (2,39 -2,42%) and HUFA (1,63 – 1,71%) concentrations in eggs of fish fed diets containing raw fish and squid supplementing were significantly higher than those of fish fed diets containing raw fish or raw fish with shrimp supplementation (P < 0.05) The DHA concentration in eggs of broodstocks fed CT + M and CT + M + T diets showed significantly higher those of fish fed other diets (P < 0.05) However, no significant differences were observed in ARA and EPA levels in eggs of broodstocks fed different diets (P > 0.05) The EPA/ARA, DHA/EPA and n-3/n- ratios were 1,30 - 1,46%; 2,89 – 3,27% and 3,01 – 3,26%, respectively and did not affected tested diets (P > 0.05) Egg diameter, floated egg rate, fertilized rate and hatching rate Broodstocks fed tested diets had no effects on egg diameter and egg’s oil droplet size (P > 0.05) Egg diameter ranged from 0,98 to 1,00 mm, while oil droplet was 0,27 – 0,28 mm The fertilized rate, floated egg rate and hatching rate were significant affected by the experimental diets fed to broodstocks (P < 0.05), resulting in highest values in fish fed diet containing raw fish with squid and shrimp supplementing The supplementation of squid or shrimp into broodstocks diets significantly improved the fertilized rate, floated egg rate compared with those of broodstocks fed raw fish diet only (Figure 3.3) Cá tươi 105 Cá tươi-Mực-Tôm b b Tỷ lệ (%) 90 75 a Cá tươi-Mực Cá tươi-Tôm c a b ab b a a ab a 60 45 30 15 Trứng thụ tinh Trứng Tỷ lệ nở Figure 3.3: Fertilized rate, floated egg rate and hatching rate of snubnose pompano fed different diets Larval quality The supplementing of shrimp and squid into diet containing raw fish fed to broodstocks significantly improved early larval size, yolk-sac size and oil droplet size of snubnose pompano (P < 0.05) (Table 3.1) The lowest deformity rate of larvae was observed in group fed CT + M+ T or CT +T diets, while the highest deformity rate was recorded in gourp fed CT diet (P < 0.05) There was no effects of tested diets fed to broodstocks on the survival rate of days old larvae (P > 0.05) In summary, the results indicated that broodstocks fed diet containing 70% raw fish; 15% squid and 15% shrimp can improve the maturity, fecundity as well as egg and larval quality of snubnose pompano 3.1.2 Effects of feeding ration fed for broodstocks on reproductive performances of snubnose pompano 3.1.2.1 Growth performance, maturity and fecundity The results showed that the feeding rations had significant effect on the growth rate, maturity and fecundity of snubnose pompano (P < 0.05) The highest maturity rate (91.49 %) was observed in broodstocks fed ration of 9% body weight, there were no significant differnces on the maturity rate of fish fed rations of 5, and 11% BW (P > 0.05) The fecundity rate of broodstocks fed feeding rations of 5, and 11% BW were 51.822, 74.626 and 77.098 eggs/kg, respectively and significantly lower than that of fish fed ration of 9% BW 3.1.2.2 Egg diameter, floated egg, fertilized rate and hatching rate The egg diameters of fish fed feeding rations of and 11% body weight showed significantly larger than those of fish fed % ration (P < 0.05) However, there were no significant effects of feeding rations on oil droplet size, fertilized rate, floated egg rate and hatching rate of snubnose pompano (P > 0.05) 3.1.2.3 The larval length, deformity and survival of larvae No significant differences were recorded on larval length, deformity and survival rate of larvae among groups, where broodstocks were fed different feeding rations (P > 0.05) In summary, the increase of feeding ration fed to broodstocks from to 11% BW did not improve the fertilized rate, hatching rate, deformity and survival rate of snubnose pompano larvae But, the growth rate, egg diameter of broodstocks significantly increased, corresponding with the increase in feeding ration The feeding ration of 9% body weight was the optimum level for reproductive performances of snubnose pompano 3.1.3 Effects of vitamin E supplementation in diet fed for broodstocks on reproductive performances of snubnose pompano 3.1.3.1 The maturity and fecundity The lowest maturity was recorded in broodstocks fed diet without vitamin E supplementing, and significantly lower than those fed diet with vitamin E supplemented levels (P < 0.05) The lowest and highest maturity of males were observed in fish fed diets without and 750 mg vitamin E supplementing, respectively No significant differences were found on the maturity of males fed diets with 250, 500 and 1000 mg vitamin E supplementations The similar results also were observed in the maturity of females, resulting in high maturity in fish fed diets with vitamin E supplementing compared with those fed diet without vitamin E supplementation (P > 0.05) 3.1.3.2 Egg quality The vitamin E supplemented levels on broodstock diets had no significant effects on egg diameters, oil droplet and floated egg (P > 0.05) However, the fertilized and hatching rate significantly improved in fish fed diets with vitamin E supplementing compared with those of fish fed the control diet (P < 0,05) 3.1.3.3 Larval quality The newly larval length was significantly affected by vitamin E supplemeted levels in broodstock diets (P < 0.05) Whereas, no significant differences were reported on the larval deformity and survival rate of larvae DAH (P > 0.05) Based on reproductive performances of snubnose pompano, the optimum vitamin E supplementing in broodstock diet was 750 mg/kg diet 3.2 Effects of induced hormones on reproductive performances of snubnose pompano 3.2.1 Effects of induced hormones on the maturity, reproductive cycle and fecundity of broodstocks The results showed that there were significant effects of induced hormones on the maturity, reproductive cycle and fecundity of snubnose broodstocks (P < 0.05) The broodstocks injected with salnine water and pituitary had not spawned, while almost broodstocks spawned after inducing to spawn using HCG, LRHa + DOM or HCG + LRHa The highest and lowest maturities was observed in fish injected with HCG (81,31%) and saline water (57,48%), respectively (Table 3.5) The reproductive cycle of broodstocks induced with HCG, pituitary and HCG + LRHa were from 32 to 35 days, and significantly shorter than those induced to spawn using saline water or LRHa + DOM The fecundity of fish induced with LRHa + DOM was significantly lower than those injected with HCG or HCG + LRHa (Table 3.5) Table 3.5: Effects of induced hormones on maturity, reproductive cycle and fecundity of snubnose pompano Hormones Saline water Pituitary HCG LRHa + DOM HCG + LRHa Maturity (%) 57,84±4,84 a 68,85±2,90 ab 81,31±6,80 b 76,40±4,16 ab 67,33±7,57 ab Reproductive cycle (day) 39,00 ± 2,08 b 33,33 ± 0,88 a 32,00 ± 2,08 a 38,67 ± 1,20 b 35,33 ± 1,45 ab Fecundity (eggs/kg) 106.407 ± 8.191 b 46.553 ± 12.987 a 102.890 ± 3.176 b Values in the same comlumn with different superscripts are significantly different (P < 0.05) 3.2.2 Effects of hormone induced reproduction on egg quality The broodstocks induced with HCG, LRHa + DOM and HCG + LRHa spawned 33 hours 30 minutes, 36 hours 15 minutes and 31 hours 30 minutes after injection There was no significant effect of induced hormones on the fertilized rate (P > 0.05) The hatching rate of group injected with HCG + LRHa was significantly higher than those induced to using LRHa+ DOM or HCG (P < 0.05) 3.2.3 Effects of hormone induced reproduction on larval quality The hormones induced reproduction had no significant effects on yolk-sac diameter, oil droplet of newly larvae, larval deformity and survival rate of larvae DAH (P > 0.05) However, the newly larval length in groups injected with HCG was significantly lower than those injected HCG + LRHa (P < 0.05) 3.3 The technical solutions for early stage production of snubnose pompano 3.3.1 Effects of stocking density on growth performance in early stage of snubnose pompano 3.3.1.1 Effects of stocking density on growth performance of snubnose pompano larvae The body weight of larvae reared at 15 fish/L was significantly higher than those of fish nursed at stocking densities of 30 and 60 fish/L (P < 0.05) However, no significant difference was observed in growth performances of larvae after 23 days of the trial period The lowest survival rate was observed in fish reared at 60 fish/L and significantly lower than those of other groups The increase in stocking density from 15 to 45 fish/L had no significant effect on survival of snubnose larvae The results indicated that the optimum stocking density for early stage production of snubnose pompano should be from 15 to 45 fish/L 3.3.1.2 Effects of stocking density on growth performances of juvenile snubnose pompano There were significant effects on growth performances and CV of juvenile snubnose pompano reared at different densities (P < 0.05) The highest SGR and lowest SGR were recorded in fish nursed at 1,5 and 4,5 fish/L, respectively The survival rates of fish cultured at 1,0 - 2,5 fish/L were significantly higher (P < 0.05) than those of juveniles reared at higher stocking densities (3,0 - 4,5 fish/L) The lowest and highest FCR were evidenced in fish cultured at 2,5 and fish/L, respectively The results showed that the optimum stocking density for juvenile snubnose pompano were from 1,5 to 2,5 fish/L 3.3.2 Effects of DHA Protein Selco enriched levels in live feed on growth performances and shock resistance of snubnose pompano larvae 3.3.2.1 Growth performances The final lengths of larvae fed diet with DHA Protein Selco (DPS) enrichment were significantly higher than that of larvae fed the control diet (P < 0.05) In the DPS enriched groups, larvae fed diet containing 50 ppm DPS enrichment showed the lowest length, whereas the highest value was recorded in fish fed diet with 200 ppm DPS enrichment 3.3.2.2 Survival and deformity The survival of larvae fed live feed with DPS enrichment significantly improved, resulting in high values (4,68 – 7,64%) compared with those fed control diet (2,29%) The highest survival rate (7,64%) was observed in fish fed diet with 250 ppm DPS enrichment, and significantly higher than those of fish fed diets with lower DPS enriched levels (4,68 – 5,91%) The increase in DPS levels from 250 to 350 ppm had no significant effect on survival rate of snubnose pompano larvae The highest deformity (28,54%) was observed in fish fed live feed without DPS enrichment, and significantly higher than those of fish in DPS enriched groups (P < 0.05) However, the increase of DPS enriched levels from 50 to 350 ppm had no significant effect on the deformity of larvae (P > 0.05) 3.3.2.3 Effects of DHA Protein Selco enriched levels in diet on shock resistances of snubnose pompano larvae The larvae fed live feed with DHA Protein Selco enrichment significantly improved the shock resistance to mechanical shock of snubnose pompano larvae at 23 DAH (P < 0.05) Larvae fed diet without or low levels of DPS enrichment showed significantly higher values of shocked rate and motarity (28,45 - 68,07% and 22,72 – 57,20%) than those of fish fed diet with high DPS enriched levels (2,22 – 8,95 and 0,58 – 4,02%), respectively (P < 0.05) The resistance to mechanical shock of larvae improved at 33 DAH, where most larvae completely weaned onto comercial diets The shocked rate and mortarity to mechanical shock were not significant different in larvae fed diets with DPS enrichment, but significantly lower than those of larvae fed no enriched diets The resistance of larvae at 33 DAH to salinity shock also was evaluated by the suddenly reduction of salinity from 33 ppt to ppt for 30 minutes The results showed that high shocked rate and mortarity (23,33 – 26,67% and 6,67 – 30,00 %, respectively) were recorded in larvae fed diet without or low DPS enriched levels Fish fed diet with high DPS enriched levels significantly improved the resistance to salinity, resulting in no mortarity in these groups compared with those of the control treatment All fish was shocked to temperature changing, resulting in high mortarity in groups fed diet without DPS enrichment (93,64 %) The mortarity significantly decreased in fish fed diet with DPS enriched levels compared with those of control group In summary, the enriched live feeds can improve the survival and growth performances of snubnose pompano larvae It also improved the resistances to mechanical, salinity and temperature shocks of larvae in this stage The DPS enriched levels of 250 ppm were optimum for snubnose pompano larvae based on growth performance and shock reisistance 3.3.3 Effects of feeding regime on growth performance of snubnose pompano 3.3.3.1 Effects of weaning time to microdiets on growth performances of snubnose pompano The weaning time to microdiets had significantly affected on growth rate and coefficient variation fo larvae from 13 to 23 DAH (P < 0.05) The lowest SGR was observed in larvae weaned to microdiets at 13 DAH The larvae weaned to microdiets at 21 DAH or more showed insignificant differences on SGR and CV (P > 0.05) The similar results also were observed in larvae from 23 to 33 DAH, resulting in significantly lower values in larvae weaned to microdiets at 13 and 15 DAH compared with those of other groups (P < 0.05) The lowest survival rate (39,89%) was displayed in larvae weaned to microdiets at 13 DAH, while larvae weaned to microdiets at 17 – 23 DAH showed significantly higher survial values (74,32 – 77,93%) than those of other groups (P < 0.05) The results in the present study indicated that the suitable weaning time to microdiets for snubnose pompano larvae rearing was 17 DAH This reduced not only Artemia provision, but also cost seed production 3.3.3.2 Effect of feeding rations on growth performances of juvenile snubnose pompano The feeding rations had significantly effects on growth, coefficient variation and FCR of juvenile snubnose pompano (P < 0.05) Fish fed the feeding ration of 3% BW showed significantly lower growth compared with those of fish fed higher rations (P < 0.05) The increase of rations from to 15%BW had no significant effects on growth performances of juvenile The highest FCR value was observed in fish fed ration of 15%BW (1,95), while juveniles fed ration of 3% BW showed the lowest FCR No significant difference was recorded in the survival of juvenile (P > 0.05) The feeding ration of 9% BW was optimum for juvenile snubnose pompano based on the growth and feed ultilization efficiency 3.3.4 Effects of photoperiod regime on growth, survival and deformity of snubnose pompano larvae 3.3.4.1 Effects of photoperiod on growth and survival of early larvae (1 - 12 DAH) In this stage, the photoperiod did not significantly affect on growth rate and coefficient variation of larvae, except survival in which the highest survival was observed in fish cultured at 18L:6D, and significantly different compared with those of fish at other treatments (P < 0.05) 3.3.4.2 Effects of photoperiod on growth and survival of snubnose pompano larvae (12 – 25DAH) The highest growth rate was observed in postlarvae cultured in 18L:6D group, and significantly different with that of 12L:12D treatment (P < 0.05) The highest and lowest survival was recorded in larvae of 8L:16D and 24L:0D groups, respectively The increase in photoperiod time from to 18 hours per day had no significant effect on the survival of snubnose pompano postlarvae The results showed that the photoperiod regime at 18L:6D was suitable for growth and survival of snubnose postlarvae The growth and survival tent to decrease in fish cultured at 8L:16D and 24L:0D 3.3.5 Effects of photoperiod and feeding frequency on growth performances and survival of juvenile snubnose pompano The results indicated that the interaction between photoperiod and feeding frequency on the growth performances and coefficient variation of fish (P > 0.05) The final length, SGR were not significantly affected with the changes in photoperiod regimes (P > 0.05) The feeding frequency had significant effects on growth rate of juvenile snubnose pompano, resulting in the lowest growth rate was observed in fish fed times per day However, the increase in feeding frequency from to times per day did not significantly affect on growth rate of juvenile pompano The coefficient variation was not affected by the photoperiod (P > 0.05), but significantly different in fish fed different feeding frequencies The CV of juveniles decreased, corresponding with the increase in feeding frequency The photoperiod and feeding frequency had no significant effect on the FCR and survival of juvenile pompano (P > 0.05), where the survival and FCR were 96,35 – 97,15% and 0,94 – 0,96, respectively The results indicated that the optimum photoperiod and feeding frequency for growth performances of juvenile snubnose pompano were 12 hours/day and times/day, respectively CONCLUSION AND RECOMMENDATIONS CONCLUSIONS - Broodstocks fed diet containing 70% trash fish, 15% shrimp, 15% squid with 750 mg/kg vitamin E supplementation, and daily feeding ration of 9% body wet weight improved the reproductive performances of snubnose pompano - Broodstock spawned after injection by using 50 µg LRHa + 10 mg DOM or 1,200 IU HCG or 500 IU HCG + 40 µg LRHa Subnose pompano injected with saline or 10 mg carp pituitary/kg broodfish did not spawn The combination of HCG 500 IU + LRHa 40 µg/kg can significantly improve the reproductive efficiency in terms of fecundity, eggs and larvae quality - The growth rate and survival of snubnose pompano significantly decreased, corresponding with increase in stocking density at the larval stage The optimum stocking density was 45 inds/L The survival, shock resistance and derfomility can be improved with increase of DHA Protein Selco enrichment at level of 250 ppm In this stage, the larvae should be weaned the micro commercial diets after 17 days old at the photoperiod of 18 hours per day - Juvenile stocked at 2.5 inds/L, fed times/day with daily feeding ration of 9% body weight and photoperiod was maintained 12 hours/day showed the best performances in terms of the growth rate, survival and feed utilization efficiency RECOMMENDATIONS - Futher study is needed to evaluate the vitamin E metabolism in muscle, liver and gonads of snubnose pompano before breeding season to determine the appropriate time for vitamin E supplementing - Determine the optimum dietary energy, protein and HUFA requirements of snubnose pompano broodstocks to improve the reproduction in terms of egg and larvae quality - Evaluate the effects of vitamin A, C, D and minerals on growth performances of larvae snubnose pompano ABSTRACTS Thesis title: “Effects of some technical factors on reproductive performances and resulted seed production of snubnose pompano (Trachinotus blochii Lacepede, 1801) in Khanh Hoa” Mayor: Aquaculture Major code: 62620301 PhD Student: Ngo Van Manh Supervisor: Ass Prof., Dr Lai Van Hung Dr Ngo Anh Tuan Educational institution: Nha Trang University Key Findings: Determined broodstock feeding regimes to improve reproductive performances of snubnose pompano Broodstock fed 70% raw fish, 15% shrimp, 15% squid with daily feeding ration 9% body weight, vitamin E supplementation in the diet was 750 mg/kg raw feed Determined the suitable hormone to stimulate snubnose pompano broodstock spawning Broodstock spawned after injected with the hormone 50 µg LRHa + 10 mg DOM or 1,200 IU HCG or 500 IU HCG + 40 µg LRHa, but the fish did not spawn when injected with saline or 10 mg carp pituitary/kg broodfish Using HCG 500 IU + LRHa 40 µg/kg fish to induce spawning was significant improving the quality of reproductive performances Provide technical solutions to improve the survival, growth and quality of snubnose pompano juvenile Larval nursery phase: rear with stocking density 45 inds/L; fed live foods enriched in DHA Protein Selco concentration of 250 ppm was significantly improved survival, resistance to shock and reduce deformities; daily photoperiod maintain 18 hours/day, started weaning microdiet at 17 days old Juvenile nursery phase: stocking density was 2.5 inds/L, fed times/day with daily ration 9% body weight and photoperiod maintain 12 hours/day PHD STUDENT Ngo Van Manh LIST OF PUBLICATION AND CONFERENCE Ngo Van Manh, Chau Viet Anh, Lai Van Hung, Ngo Anh Tuan, 2013 Effects of photoperiod and daily feeding frequency on growth performance and survival of juvenile snubnose pompano (Trachinotus blochii) Journal of Fisheries Science and Technology 4, pp 27-33 Ngo Van Manh, Tran Van Dung, Lai Van Hung, 2014 Effects of stocking density on growth performance and survival of juvenile snubnose pompano (Trachinotus blochii) Journal of Fisheries Science and Technology 15, pp 55 – 59 Manh V Ngo, Phuc N.T Le, Hung V Lai, Tuan A Ngo, Tung Hoang, 2014 Morphological deformity and performance of snubnose pompano Trachinotus blochii larvae fed with enriched livefood 2014 selected publications Meeting the needs through research innovation in Biotechnology, International University VNU HCMC, Agriculture Publishing House, 101 – 108 Ngo Van Manh, Lai van Hung, Tran Van Dung, Hoang Thi Thanh, 2015 Effect of feed rate on growth and survival rate of juvenile snubnose pompano Vietnam Science Technology Review, Volume 1, Number 3, March 2015, 42 – 46 Ngo Van Manh, Le Nguyen Thien Phuc, Lai Van Hung, Ngo Anh Tuan, 2014 Performance of snubnose pompano fed with DHA-enriched livefoods International Vietnam – Taiwan conference on advanced mariculture technology 18 – 19, June 2014, Nha Trang, Vietnam [...]... broodstocks to improve the reproduction in terms of egg and larvae quality - Evaluate the effects of vitamin A, C, D and minerals on growth performances of larvae snubnose pompano ABSTRACTS Thesis title: Effects of some technical factors on reproductive performances and resulted seed production of snubnose pompano (Trachinotus blochii Lacepede, 1801) in Khanh Hoa Mayor: Aquaculture Major code: 62620301... suitable weaning time to microdiets for snubnose pompano larvae rearing was 17 DAH This reduced not only Artemia provision, but also cost seed production 3.3.3.2 Effect of feeding rations on growth performances of juvenile snubnose pompano The feeding rations had significantly effects on growth, coefficient variation and FCR of juvenile snubnose pompano (P < 0.05) Fish fed the feeding ration of 3% BW showed... vitamin E supplemeted levels in broodstock diets (P < 0.05) Whereas, no significant differences were reported on the larval deformity and survival rate of larvae 3 DAH (P > 0.05) Based on reproductive performances of snubnose pompano, the optimum vitamin E supplementing in broodstock diet was 750 mg/kg diet 3.2 Effects of induced hormones on reproductive performances of snubnose pompano 3.2.1 Effects of. .. than those injected HCG + LRHa (P < 0.05) 3.3 The technical solutions for early stage production of snubnose pompano 3.3.1 Effects of stocking density on growth performance in early stage of snubnose pompano 3.3.1.1 Effects of stocking density on growth performance of snubnose pompano larvae The body weight of larvae reared at 15 fish/L was significantly higher than those of fish nursed at stocking densities... respectively CONCLUSION AND RECOMMENDATIONS 1 CONCLUSIONS - Broodstocks fed diet containing 70% trash fish, 15% shrimp, 15% squid with 750 mg/kg vitamin E supplementation, and daily feeding ration of 9% body wet weight improved the reproductive performances of snubnose pompano - Broodstock spawned after injection by using 50 µg LRHa + 10 mg DOM or 1,200 IU HCG or 500 IU HCG + 40 µg LRHa Subnose pompano injected... performances of snubnose pompano larvae It also improved the resistances to mechanical, salinity and temperature shocks of larvae in this stage The DPS enriched levels of 250 ppm were optimum for snubnose pompano larvae based on growth performance and shock reisistance 3.3.3 Effects of feeding regime on growth performance of snubnose pompano 3.3.3.1 Effects of weaning time to microdiets on growth performances. .. In summary, the increase of feeding ration fed to broodstocks from 5 to 11% BW did not improve the fertilized rate, hatching rate, deformity and survival rate of snubnose pompano larvae But, the growth rate, egg diameter of broodstocks significantly increased, corresponding with the increase in feeding ration The feeding ration of 9% body weight was the optimum level for reproductive performances of. .. optimum stocking density for early stage production of snubnose pompano should be from 15 to 45 fish/L 3.3.1.2 Effects of stocking density on growth performances of juvenile snubnose pompano There were significant effects on growth performances and CV of juvenile snubnose pompano reared at different densities (P < 0.05) The highest SGR and lowest SGR were recorded in fish nursed at 1,5 and 4,5 fish/L,... different factors and interaction in two factor experiments The statistical significance was evaluated at P < 0.05 All charts were drawed using Microsoft Excel CHAPTER 3: RESULTS AND DISCUSSIONS 3.1 Effects of different trash fish, feeding rations and vitamin E levels fed to broodstocks on fecundity, egg and larval quality of snubnose pompano 3.1.1 Effects of different trash fish diets for broodstock on. .. terms of the growth rate, survival and feed utilization efficiency 2 RECOMMENDATIONS - Futher study is needed to evaluate the vitamin E metabolism in muscle, liver and gonads of snubnose pompano before breeding season to determine the appropriate time for vitamin E supplementing - Determine the optimum dietary energy, protein and HUFA requirements of snubnose pompano broodstocks to improve the reproduction ... effeciency of snubnose pompano Acording to these reasons, the thesis Effects of some technical factors on reproductive performances and resulted seed production of snubnose pompano (Trachinotus blochii. .. title: Effects of some technical factors on reproductive performances and resulted seed production of snubnose pompano (Trachinotus blochii Lacepede, 1801) in Khanh Hoa Mayor: Aquaculture Major... the effects of technical solutions on eggs, larvae quality and juvenile rearing efficiency of snubnose pompano in Khanh Hoa province Effects of different trash fish, feeding rations and vitamin