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1.
Live prey used in aquaculture to feed marine larval fish – rotifer and Artemia nauplii – lack the necessary levels of n‐3 polyunsaturated fatty acids (n‐3 PUFA) which are considered essential for the development of fish larvae. Due to the high voracity, visual feeding in conditions of relatively high luminosity, and cannibalism observed in meagre larvae, a study of its nutritional requirements is needed. In this study, the effect of different enrichment products with different docosahexaenoic acid (DHA) concentrations used to enrich rotifers and Artemia metanauplii have been tested on growth, survival, and lipid composition of the larvae of meagre. The larvae fed live prey enriched with Algamac 3050 (AG) showed a significantly higher growth than the rest of the groups at the end of the larval rearing, while the larvae fed preys enriched with Multigain (MG) had a higher survival rate. DHA levels in larvae fed prey enriched with MG were significantly higher than in those fed AG‐enriched prey. High levels of DHA in Artemia metanauplii must be used to achieve optimal growth and survival of meagre larvae.  相似文献   

2.
There is a need to develop low-cost methods for larviculture that emphasize disease prevention. We evaluated stagnant water larviculture in flounder Paralichthys olivaceus using rotifer amictic eggs treated with glutaraldehyde. Growth and survival of the larvae were similar to in larvae reared by standard running water larviculture with daily feeding of rotifers (control). In the experimental group, the n-3 highly unsaturated fatty acid content of rotifers in the rearing water was higher than in the enriched rotifers fed to the control group. We also observed a similar pattern for the fatty acid composition of flounder larvae. The viable bacterial counts associated with rotifers in stagnant water were lower than those associated with enriched rotifers, and there were fewer bacterial genera. However, the viable bacterial count was the same or higher in the experimental rearing water compared with that in the control group. The α-Proteobacteria and CytophagaFlavobacteriumBacteroidetes group dominated the bacterial community structure after larval hatching. To our knowledge, this is the first time that stagnant water larviculture, using only disinfected amictic eggs, has been successfully demonstrated on a mass production scale. This method appears to offer benefits including improved nutrition, more favorable bacterial communities, and lower cost.  相似文献   

3.
One approach to ongrow juvenile European lobster, Homarus gammarus, is to utilize land based rearing systems, incorporating automated feeding, individual culture and provision of stable pelleted feeds, preferably using sustainable ingredients. We initiated three feeding experiments to investigate the general suitability of ingredients produced from seafood by‐products as novel feeds for H. gammarus, in terms of promoting survival, development and growth of post‐larval lobsters from post‐larvae (PL) stage IV to the first juvenile stage (stage V). The first experiment was designed to screen an array of candidate, locally produced, novel protein sources on growth performance parameters. This initial experiment revealed that PL reared on a raw (i.e. wet, unprocessed shrimp) feed used as a reference showed superior performance to those reared on experimental feeds containing fishmeal, herring protein isolate or mussel meal; however, a novel type of shrimp meal, produced by flocculation from waste water, promoted the best PL performance of any experimental feed. A second experiment was designed to test the effect of drying method and to optimize the form of a wet shrimp reference feed used by lobster hatcheries. This showed that the performance of PL reared on experimental freeze‐dried shrimp feed was not significantly different to those reared on the wet, unprocessed shrimp used as a reference feed. However, lobsters offered experimental oven‐dried shrimp feed (with or without an immune supplement) resulted in significantly lower survival or growth performance. A third and final experiment was designed in an attempt to improve a candidate herring‐based protein source, by supplementing with nutrients found in shrimp. However, the results showed that PL reared on the wet reference shrimp feed still showed superior growth and survival than those reared on a herring feed alone, or supplemented with additives found in shrimp meal (either glucosamine, astaxanthin or both supplements combined). The high survival and growth, low incidence of moulting problems and high availability of waste shrimp material, suggest that non‐heat‐treated shrimp products are a promising feed ingredient for post‐larval European lobsters.  相似文献   

4.
Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L?1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L?1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L?1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L?1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L?1 with the availability of shelter for optimal larviculture condition.  相似文献   

5.
Predation of zoeas by megalopae of Ucides cordatus is frequently observed in the laboratory during larval rearing, a phenomenon that could considerably reduce the output of larviculture. Experiments were carried out in the present study to assess how the survivorship of larvae at the end of the larviculture is influenced by cannibalism by megalopae on the larvae of earlier stages, as well as on other megalopae. In addition, tests were performed to assess whether the adoption of different feeding protocols can decrease cannibalism rates. Experiments were carried out in plastic vials containing ocean water (salinity 25 g L?1) under controlled environmental conditions (26 °C and 16:8 h LD photoperiod). An ensemble analysis of all the developmental stages indicated that zoeal mortality rates were significantly higher in the presence of megalopae, a result that is consistent with cannibalism by megalopae. However, separate analysis for each developmental stage indicated that only zoea IV, V and VI show reduced survivorship. No cannibalism was detected among megalopae. Food supplementation using Artemia sp. at a density of 6 nauplii mL?1 proved to be successful in reducing cannibalism rates, whereas supplementation at a lower density (0.3 nauplii mL?1) failed to show such an effect. The implications of these results for the larviculture of U. cordatus are discussed.  相似文献   

6.
Problems of limited number of dry feeds as supplement or replacement of live feeds have led to poor larval nutrition in many species of fish. Therefore, the suitability of co‐feeding 8‐day‐old African catfish (Clarias gariepinus) posthatch larvae using live feed (Artemia salina) and formulated dry diet containing freshwater atyid shrimp (Caridina nilotica) during weaning was investigated. The experiment ended after 21 days of culture and respective groups compared on the basis of growth performance, survival, feed utilization and nutrient utilization. Larvae co‐fed using 50%Artemia and 50% formulated dry diet resulted in significantly (P < 0.05) better growth performance, food gain ratio (FGR), protein efficiency ratio (PER) and productive protein values (PPV) than other treatments. The lowest growth performance occurred in larvae weaned using 100% formulated and commercial dry diets. Better survival of over 90% was obtained in larvae weaned using 50%Artemia and 50% dry diet, while abrupt weaning using 100% dry diets resulted in lower survival (<75%). These results support a recommendation of co‐feeding C. gariepinus larvae using a formulated dry diet containing C. nilotica and 50% live feed when weaning is performed after 8 days posthatching period.  相似文献   

7.
The spotted rose snapper (Lutjanus guttatus) and bullseye puffer (Sphoeroides annulatus) are fish species from the tropical Eastern Pacific for which controlled production of larvae and juveniles has been accomplished in recent years. Diverse topics relating to their biology and aquaculture production are currently under study, in particular the nutrition and feeding aspects required to formulate practical feeds and rearing protocols. Improvements in larval growth and survival are possible by feeding live food organisms with natural or enhanced essential fatty acids content and highly digestible artificial microdiets. The ontogeny of the digestive tract and the expression and activity of digestive enzymes have been described for S. annulatus larvae. The effect of various protein and lipid levels on growth and feed utilization has been studied in juvenile and on-growing fish. Both species have carnivorous feeding habits and require high levels of protein in their diets, from 40% to 45% (dry weight) in spotted rose snapper and above 50% in bullseye puffer, with the younger stages requiring the highest protein levels. Encouraging results have been obtained in feeding experiments with different sources of dietary protein from animal and plant origin to evaluate their suitability as feed ingredients in practical diets. Optimization of fish culture practices through feeding management has also been investigated. Trials with various fish densities and feeding frequencies in intensive culture systems are providing information to improve feed utilization and growth in on-growing fish. Further research is underway to evaluate factors in broodstock nutrition which have an impact on egg and larval quality, and into the use of various commercially available oil sources in on-growing diets. In this paper, the results on nutrition and feeding research with both species are reviewed and research needs to support their commercial production in the region are discussed.  相似文献   

8.
A feeding experiment was conducted to evaluate the effect of rotifers (Brachionus plicatilis) and Artemia sp. enriched differently on early growth, survival and lipid class composition of Atlantic cod larvae (Gadus morhua). Rotifers enrichments tested were: (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) a combination of Pavlova sp. paste and AlgaMac 2000®. The same treatments were tested with Artemia as well as a combination of DC DHA Selco® and AlgaMac 2000® as a fourth treatment. After rotifer feeding, the larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw)] were significantly heavier than larvae from treatment 2 (1.03 ± 0.04 mg dw). After feeding Artemia, the larvae from treatment 1 were significantly heavier (12.06 ± 2.54 mg dw) than those from treatments 3 (6.5 ± 0.73 mg dw) and 4 (5.31 ± 1.01 mg dw). Treatment 3 resulted in the best survival through the 59 days of larviculture. After rotifer feeding, high larval concentrations of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA) and ω6 docosapentaenoic acid (ω6DPA) could be linked to better larval growth and survival while after feeding Artemia, high larval DHA/EPA ratios (~3) and high DPA/AA ratios (>1) could be linked to better survival.  相似文献   

9.
This research examined the effect of initial stocking density and feeding regime on larval growth and survival of Japanese flounder, Paralichthys olivaceus. Larval rearing trials were conducted in nine 50‐L tanks with different initial stocking densities combined with different feed rations (20 larvae/L with standard feed ration [LD], 80 larvae/L with standard feed ration [HD], and 80 larvae/L with four times the standard feed ration [HD+]). Larvae were stocked on 0 days posthatch (DPH) following hatching of the fertilized embryos. Larval total length (TL), survival rates, and final densities were observed on larval settlement (32 DPH) to evaluate larval rearing performance. At 32 DPH, there were no significant differences (p > .05) in TL or survival rates between the LD (46.5 ± 17.0%) and HD+ (40.3 ± 9.4%). The TL and survival rate of HD (23.1 ± 3.5%) were significantly lower than that of LD and HD+ (p < .05). However, the larval density of HD was significantly higher than that of LD (p < .05). HD+ achieved the best larvae production (32.27 ± 7.51 larvae/L), supported by sufficient food source, high water exchange, and proper water quality management (routine siphoning, surface skimming). The larval‐rearing protocols and larval development from hatching to metamorphosis is described in detail, with corresponding photographs taken during the experiment.  相似文献   

10.
The sutchi catfish Pangasianodon hypophthalmus is an important species for aquaculture in Southeast Asia. However, larvae typically have low survival rates due to their predilection for cannibalism during rearing. This study investigated larval feeding behavior and rearing conditions. The former experiments were performed to elucidate the role of sensory organs in feeding, and the latter experiments examined the effect of dim light on larval rearing and survival rates. Neither lighting conditions (light and dark) nor blocking of free neuromasts by streptomycin had significant effects on feeding behavior. Therefore, the feeding behavior of sutchi catfish larvae most likely depends on chemosensing rather than visual sensing. In the later experiments, larval rearing at 0.1 l× yielded significantly higher survival rates than other lighting conditions (0.00, 1, 10, 100 l×). Survival in the 0.1 l× group was almost three times higher than in the 100 l× group. Moreover, larvae reared under 0.1 l× showed steady growth. Therefore, it is concluded that 0.1 l× is the optimum light intensity for sutchi catfish larval rearing.  相似文献   

11.
Two experiments were conducted into the rearing of crucian carp larvae under controlled conditions in an experimental closed water system. In both cases, the rearing lasted 21 days. The first experiment concerned the initial stocking density (from 50 to 600 individuals per l), whilst the second one studied the first food offered (two types of Artemia nauplii, decapsulated Artemia cysts and three types of commercial feeds) which were applied at the moment of exogenous feeding commencement. The best results were obtained using 50 larvae per l, whilst there were no significant differences within the range 200–600 larvae per l. The application of dry feed had a negative influence on the survival and other parameters. The highest survival rate was found in the groups fed with freshly hatched Artemia naupli. The results obtained indicate that the rearing of crucian carp larvae may be successfully conducted in very high stocking densities. However, the very high sensitivity of crucian carp larvae to the type of food offered during the initial days of life should be taken into account. The data presented in this article could be very useful in crucian carp larviculture.  相似文献   

12.
We studied the effects of light intensity on larval activity, feeding behaviour, growth and survival of a candidate species for aquaculture – sablefish (Anoplopoma fimbria). Of six light intensities ranging from 2 to 750 lux at the water surface, the greatest surviving biomass in small tanks was observed at 12–42 lux. In another experiment in larger tanks, behavioural observations showed that larvae fed poorly under light brighter than 800 lux but fed better at lower light intensities, depending on tank type. In a separate experiment, where live feed densities were varied between 2.5 and 17.5 rotifers per mL of tank water, surviving biomass and dry weight increased with higher feed densities. These experiments help refine methods for rearing larval sablefish by demonstrating effects of light intensity and feed density on larval performance.  相似文献   

13.
This study relied on the day‐by‐day analysis of bioenergetics and prey size preference in larvae and juveniles of Hemibagrus nemurus selected at random, held in isolation (28.5°C, 12L:12D) and feeding ad libitum on conspecifics [21 fish, 12–46 mm total length (TL), dry mass (DM) of 1–145 mg]. Several traits concur to make young H. nemurus highly cannibalistic: (1) high predation capacities (largest prey = 88% and 70% TL in fish of 8 and >40 mm TL, respectively), (2) opportunistic feeding behaviours with no marked size preference and (3) an unusual combination of high food intake (>100% DM at 1 mg DM) and very high gross conversion efficiency (>0.70). A growth model was constructed from the top performances of fish feeding maximally (16 of 21 fish) and indicated that the risk of cannibalism would be high and permanent except for meal frequencies over five daily meals. Cannibals emerging spontaneously under communal rearing (6 fish L?1, three daily meals) grew more slowly or just at the same rate as predicted by the growth model constructed from siblings selected at random. This indicates that the individuals that become cannibals do not possess higher intrinsic capacities for growth than others.  相似文献   

14.
The European brown shrimp, Crangon crangon, is a highly valued commercial species in Europe. These shrimp fisheries are characterized by strong seasonal variations in average landings. Attempts to ‘catch and hold’ wild adults in land‐based rearing systems have been proven to be very difficult, due to inadequate feed, slow growth and high mortality. In this study, we have optimized design and operation procedures of a small‐scale static larval rearing system for the culture of C. crangon larvae. Focus was on optimizing larval survival via water temperature, feed selection, feeding regime and density. This is the first report that shows that C. crangon larvae can be reared at high densities of 300 larvae L‐1 with high survival of 73.5 (± 5.4)% under laboratory conditions. In these systems, larvae can be fed exclusively Artemia nauplii according to a feeding regime which is adjusted based on major moulting events. Addition of microalgae may further increase survival by 10%. The information gathered during this research can be applied to further optimize larval development in either flow‐through or recirculation systems.  相似文献   

15.
Adequate nutrition is a principal factor in controlling survival and growth in crustacean larval culture. The present study examined the effects of starvation before or after feeding on survival, total intermoult period and postmoult size of phyllosoma of the western rock lobster, Panulirus cygnus. Individually held instar 1 larvae were reared at 25 °C and submitted to initial periods of starvation to determine the 50% level of the point-of-no-return (PNR50), and initial periods of feeding to determine the 50% level of the point-of-reserve-saturation (PRS50). As the initial starvation periods before feeding increased, the total intermoult period for instar 1 larvae that survived increased. The PNR50 was 4.6 days. The different initial feeding periods before starvation resulted in a difference in postmoult size of larvae after moulting to instar 2, but had little effect on the total intermoult period. Larvae fed for the shortest periods were significantly smaller than those fed longer. The PRS50 was 3.6 days. For both treatments, limited effects of the starvation or feeding regimes were apparent for larvae that moulted to instar 2 and continued development to instar 3. When larvae were fed before PNR50, there were no delayed effects of the initial starvation period. Initial feeding periods longer than 5–6 days did not significantly affect larval survival or growth. This information will be useful in the design of feeding regimes in phyllosoma culture.  相似文献   

16.
The fat snook, Centropomus parallelus, is a commercially valuable marine fish species with potential for aquaculture. This paper describes the development of technology for mass production of fat snook juveniles at the Experimental Fish Hatchery of the Universidade Federal de Santa Catarina, focusing on research about reproduction, larviculture, and juvenile rearing. Induced spawning of wild fat snook was first achieved in 1991 with a single injection of human chorionic gonadotropin (hCG). There was a substantial increase in egg quality when broodstock was conditioned in maturation rooms and induced to spawn. Different dosages of luteinizing hormone-releasing hormone analogue (LHRHa) with saline injection and colesterol implant were also tested. As fat snook exhibits group-synchronous oocyte development, females could be induced to spawn (with 35–50 μg kg−1 of LHRHa) once a month, resulting in up to four consecutive spawnings. Results of larval culture were highly variable at the beginning; survival rates were frequently around 1% until the juvenile stage. Several experiments were conducted to evaluate the effect of environmental factors and feeding quality on survival and growth. With the improvement of the spawning induction technique and better larviculture practices, survival rates increased to 10–30%. Studies on the particular requirements of juveniles in terms of stocking density, feeding, nutrition, and environmental factors were also performed in order to improve growth rates and feed utilization. The present study demonstrates the feasibility of mass production of fat snook juveniles. However, further research is needed to develop cost-effective grow-out technology.  相似文献   

17.
Alligator gar, Atractosteus spatula, are a new aquaculture species with many aspects about rearing unknown. Alligator gar are cannibalistic during their larval stage and methods to minimize cannibalism should be developed to increase overall survival. Growth and survival were determined for larvae fed pelleted floating food only or fed pelleted floating food supplemented with live Artemia spp. nauplii for the first 7 d of exogenous feeding (5 d after hatching [d.a.h.] to 12 d.a.h.). Total length, weight, condition, and specific growth rate (SGR) was determined at 12 and 20 d.a.h. Fish supplemented with Artemia were larger by 12 d.a.h. and continued to be at 20 d.a.h. than fish fed only floating food. SGR was higher at both 12 and 20 d.a.h. for fish that received the Artemia supplement. Survival was higher for fish supplemented with Artemia (71%) than for the floating food only treatment (43%). Cannibalism was the primary cause of mortalities and was higher in fish fed floating food only (44%) compared to Artemia supplemented fish (19%). Artemia may elicit a stronger feeding response and improve acceptance of pelleted floating foods. Results suggest an improved feeding regime compared to previous feeding regimes used in rearing larval alligator gar.  相似文献   

18.
The pullet carpet shell Venerupis corrugata is an economically valuable species in several European countries, however, nowadays stocks are under high fishing pressure. Hatchery production of juveniles for release is a major contributor to strengthen the stock and consequently improve the sustainability of the natural stocks. This study aimed to determine the feasibility of rearing V. corrugata larvae with different larval densities (10, 40 and 200 larvae per mL) in a recirculating aquaculture system (RAS), compared with the traditional larval rearing methodology (Batch). The mean survival, growth and metamorphic rate of V. corrugata larvae in RAS was higher (11.1%; 71.3 μm; 21.6% respectively) than in the Batch system, in all tested densities. The larval growth was not affected by the initial density until 40 larvae per mL, however, 200 larvae per mL decreased the larval growth in length nearly 54 μm. The larval rearing time was shortened in 2 days in the RAS system. The physical, chemical and microbiologic parameters suggested that the tested densities were not excessive to disturb the biofilter stability of RAS. The V. corrugata larval rearing performed at high larval stocking densities in RAS system present a reduction in the operating costs to produce this species.  相似文献   

19.
Many coral reefs are threatened because of anthropogenic impacts such as destructive fishing methods for marine ornamentals. The marine ornamental industry is currently almost completely dependent upon wild collections. The development of commercially feasible methods to culture ornamental species could help to reduce the need for wild‐collected specimens and reduce pressure on coral reefs. Advances in larval rearing and nutrition would help overcome the bottlenecks that impede the commercial production of many marine ornamental species. This article focuses on research for improving the production of the fire shrimp, Lysmata debelius. Experiments were performed with larval fire shrimp to evaluate (1) the importance of essential fatty acid enrichment of live prey (rotifers and Artemia) and (2) feeding penaeid shrimp muscle tissue to improve survival to metamorphosis. We also provide the fatty acid composition of Day‐1 posthatch fire shrimp larvae. The enrichment of live prey with docosahexaenoic acid did not improve larval growth, survival, or time to metamorphosis, but larvae fed live prey together with pureed penaeid shrimp muscle had survival rates of 9.8 ± 1.2%. The data and protocols developed in this study provide a foundation and baseline for future fire shrimp larval studies.  相似文献   

20.
Considering the well‐known problems arising from the use of rotifers and Artemia as live prey in larval rearing in terms of fatty acid deficiencies, the aim of this study was to evaluate a partial or complete replacement of traditional live prey with preserved copepods during the larviculture of gilthead sea bream (Sparus aurata). Sea bream larvae were randomly divided into 4 experimental groups in triplicates: group A larvae (control) fed rotifers followed by Artemia nauplii; group B fed a combined diet (50%) of rotifers–Artemia and preserved copepods; group C fed rotifers followed by preserved copepods; and group D fed preserved copepods solely. Survival and biometric data were analysed together with major molecular biomarkers involved in growth, lipid metabolism and appetite. Moreover, fatty acid content of prey and larvae was also analysed. At the end of 40 days treatment, a stress test, on the remaining larvae, was performed to evaluate the effects of different diets on stress response. Data obtained evidenced a positive effect of cofeeding preserved copepods during sea bream larviculture. Higher survival and growth were achieved in group B (fed combined diet) larvae respect to control. In addition, preserved copepods cofeeding was able to positively modulate genes involved in fish growth, lipid metabolism, stress response and appetite regulation.  相似文献   

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