Combined effects of water temperature and daily food availability period on the growth and survival of tench (Tinca tinca) larvae

A 16‐day experiment was designed to find the best combination of water temperature (27, 30, 33°C) and daily duration of food availability (12, 18, 24 h) for larval tench (Tinca tinca) growth and survival. Larvae with an initial mean size of 5.7 mm total length (TL) and 0.7 mg wet body weight (BW) were stocked at 15 L^?1. Larvae were fed in excess with live Artemia nauplii with the period of food availability lasting 12, 18 or 24 h daily. The largest final larval size was recorded at 27 and 30°C in groups fed for 24 h a day (17.7 and 17.9 mm TL, 76.1 and 77.7 mg BW, respectively). The combination of the highest temperature and the longest daily food availability was the only set of conditions under which final larval survival was affected (95.4% survival; 98.7–99.9% under all other conditions). The combination of water temperature of about 28.6°C and continuous food availability is recommended as the optimum combination for rearing T. tinca larvae under controlled conditions. Providing continuous food supply to fish larvae under aquaculture conditions was also advantageous in helping to mitigate the effects of slower growth relative to developmental progress, which can occur at high water temperatures. However, should one wish to limit the daily feeding period to 12 h per day, the use of a water temperature between 27.4 and 27.9°C would be the best solution.     

Effects of three cold weather event simulations on early life stages of Southern Flounder (Paralichthys lethostigma)

ABSTRACT

To determine the minimum age/size at which Southern Flounder, Paralichthys lethostigma, can safely be moved to outdoor rearing facilities in Texas, we examined survival of simulated temperature drops in two distinct life stages: premetamorphic larvae and two size classes of postmetamorphic juveniles (small = 9.8 ± 0.3 mm in TL; large = 19.7 ± 0.6 mm). Temperature was lowered by ?0.33°C/h to 4°C, 7°C, or 10°C, held for 48 h and then raised at +0.33°C/h back to normal rearing temperature. Fish were monitored daily for survival. Larger postmetamorphic flounder had high survival for all temperature treatments (89%–100% survival), whereas both premetamorphic larvae and smaller postmetamorphic juveniles had low survival (<30%) for all temperature treatments.     

Induced breeding and larval rearing of Surubí, Pseudoplatystoma fasciatum (Linnaeus, 1766), from the Bolivian Amazon

Brooders of Surubí (Pseudoplatystoma fasciatum) were caught in the Ichillo River (Bolivian Amazon) and adapted to captivity conditions for 1 year in the facilities of the experimental aquaculture station of ‘El Prado’ (Santa Cruz de la Sierra) under natural temperature and photoperiod conditions. Induced reproduction was obtained by means of Ovaprim^® (Syndel, Canada) injections and artificial fertilization. Sperm and ova were obtained by gentle stripping of male and female brooders. Fertilized eggs were incubated in 60 L Zug jars. A mean hatching rate of 73.7±19.0% was obtained after 24 h at 26.5 °C. For larval rearing, several protocols were tested with different settings of photoperiod, light intensity, food type and period of distribution, and stocking density. The best survival rates were obtained with Artemia nauplii feeding in total darkness. A high level of aggressiveness between larvae and precocious appearance of jumpers was observed, but these can be controlled with appropriate rearing conditions.     

Determination of periods of sensitivity to low-salinity and low-temperature conditions during the early development of cultured Japanese eel Anguilla japonica larvae with respect to the rate of morphological deformity at completion of yolk resorption

The present study analyzed the rate of occurrence of deformities at completion of yolk resorption after Japanese eel larvae were exposed to low-salinity (29 psu) or low-water-temperature (20 °C) conditions (after they had been reared under suitable conditions: 34 psu, 25 °C) at various points between 0 and 8 days post-fertilization (dpf) in order to determine the period of sensitivity of the larvae to low-salinity or low-temperature conditions. No significant differences were observed between the rate of deformed larvae obtained in the groups reared under suitable conditions and the corresponding rates in groups that were exposed to low-salinity or low-temperature conditions at 4 dpf or later, but the frequency of normal larvae showed a downward trend in experimental groups that were subjected to low-salinity or low-temperature conditions at 3 dpf or earlier. Occurrence rates of pericardial edema were significantly higher in experimental groups that were exposed to low-salinity or low-temperature conditions at 2 dpf or earlier. Therefore, it was concluded that the rearing conditions for Japanese eel larvae should be maintained at 34 psu salinity and 25 °C until at least 4 dpf in order to reduce the occurrence of larval deformity at completion of yolk resorption.     

Dynamics of yolk sac and oil droplet utilization and behavioural aspects of swim bladder inflation in burbot, Lota lota L., larvae during the first days of life, under laboratory conditions

The study concerns investigation of early larval development of burbot, Lota lota. As part of a two-year study, the first 15 days (until the end of yolk sac resorption) of burbot larvae development under controlled conditions were examined. The aim of the study was to observe the moment of swim bladder inflation and the behavioural aspects of this process, as well as the analysis of yolk and oil droplet resorption and the beginning of exogenous nutrition. It was observed that larvae began to inflate their swim bladder on the 3rd day post-hatch. On 5 DPH, none of the larvae without an inflated bladder was able to swim up the distance separating it (10 cm) from the water surface. Since 9 DPH, 50 % of larvae started exogenous feeding, and the absence of yolk was observed on 13 DPH and oil droplet on 14 DPH, while on 15 DPH, 100 % of feeding larvae were observed. The presented results indicate that the analyzed period is critical for burbot, and it is characterized by a high mortality rate (over 60 %). Additionally, the results suggest that, under controlled conditions, the latest moment when burbot larvae should be given exogenous food is 9–10 DPH and until the moment of the swim bladder inflation, larvae should be kept in tanks with a low water depth (up to 10 cm). The data presented in this study could have a significant influence on the efficiency of larvae rearing, both for aquaculture and for restocking purposes.     

Tench (<Emphasis Type="Italic">Tinca tinca</Emphasis> L.) larvae rearing under controlled conditions: density and basic supply of <Emphasis Type="Italic">Artemia</Emphasis> nauplii as the sole food

After artificial reproduction of tench, larvae must be maintained indoors, and studies on rearing conditions are needed, focussing on the reduction of labour and costs. Three experiments on larvae (5th day post-hatch) were conducted for 25 days using Artemia nauplii as the sole food in order to determine basic feeding and density conditions during the first rearing period. Tench were maintained in 25 l fibreglass tanks, supplied with an artesian water flow throughout of 0.2 l min⁻¹. Water temperature was 22.5 ± 1°C, and the photoperiod was natural. Larvae fed on a restricted amount of nauplii reached high survival rates, even with the minimum of 50 nauplii larva⁻¹ day⁻¹. This amount of food may be sufficient at least for the first 25 days of exogenous feeding if fast growth is not the priority, and high densities can be maintained with good survival rates (over 90% up to 160 larvae l⁻¹ and 77% with 320 larvae l⁻¹). When food was supplied in excess once a day, high survival rates were achieved (91–97%), without differences among the densities tested. Animals at a density of 100 l⁻¹ reached the highest length (15.57 mm) and individual weight (46.8 mg). This growth is greater than those reported in studies feeding several times a day. It could be deduced that, while live food remains available for tench, it is not necessary to feed so frequently. Considering the relationship among the initial number of animals, final survival and growth and ration supplied, the new data reported here are useful to establish suitable stocking densities under both culture and experimental conditions.     

Effect of water temperature and light intensity on swim bladder inflation and growth of red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> larvae

This study aimed to examine the effect of different water temperatures and light intensities on swim bladder inflation (SBI) and growth of red sea bream Pagrus major larvae to improve rearing techniques for this species. Two sets of experiments were conducted: different rearing temperatures were used in experiment 1 (19, 21, 23, and 25 °C), and different light intensities in experiment 2 (250, 1000, 4000, and 16,000 lx). Water temperature did not affect SBI frequency, but SBI initiation was accelerated at higher temperature, i.e., it was initiated on 3 days post-hatching (dph) at 25 °C and on 6 dph at 19 °C, suggesting that the promotion period for SBI, which needs a surface skimmer to be  run, also accelerated with increasing temperature in red sea bream larviculture. A higher temperature also significantly promoted larval growth, although the notochord of larvae at SBI initiation was shorter at higher temperatures. Light intensity had no effect on either the initiation or the frequency of SBI. However, light intensity of 250 lx significantly reduced early larval growth compared to light intensities higher than 1000 lx. These results indicate that light at an intensity greater than 1000 lx at the water surface is suitable for the early larviculture of red sea bream.     

Influence of temperature and feeding regimes on growth and notochord deformity in reared <Emphasis Type="Italic">Anguilla japonica</Emphasis> leptocephali

The high mortality rate of reared Japanese eel Anguilla japonica larvae is largely due to lower growth rate and the higher rate of deformed larvae. To establish an effective rearing protocol for this species, we examined the effects of water temperature and feeding regimes on their growth and notochord kyphosis. Larvae at 165 days post hatching were reared for 28 days at mean temperatures of 24, 25 and 27 °C, and were fed 4 or 6 times per day. Larval growth rate was significantly higher in larvae reared at 24–25 °C and fed 6 times per day. However, growth rate was significantly reduced at 27 °C, suggesting a shortage of metabolic energy due to an elevated cost of the higher basal metabolic rate at higher temperatures and low nutritional performance of currently used artificial diet. Notochord kyphosis was promoted by elevated water temperature, and two-way ANOVA showed that water temperature and feeding frequency had combined effects on the deformity. These findings suggest the importance of concurrently manipulating both environmental and nutritional factors to produce healthy eel larvae in captivity.     

Effects of water temperature on feeding and growth of juvenile marbled flounder <Emphasis Type="Italic">Pseudopleuronectes yokohamae</Emphasis> under laboratory conditions: evaluation by group- and individual-based methods

To determine the optimal temperature for juvenile (0 year old) marbled flounder Pseudopleuronectes yokohamae, juveniles of 40–54 mm standard length were reared at six temperature conditions in the range of 8–26 °C, using group- and individual-based methods. Growth of juveniles increased from 8 to 20 °C but decreased from 20 to 26 °C, irrespective of the rearing method used. Food intake was greatest at 20 and 24 °C compared with other temperatures, while feed conversion efficiency was greater at 20 °C than 24 °C in individual rearing. Individual rearing provided more information such as individual variations in growth and food consumption, suggesting the importance of individual-based experiments for exploring the optimal temperature for fish.     

Survival and growth of larval and juvenile tench, Tinca tinca L., fed different diets under controlled conditions

Abstract. Tench, Tinca tinca L., larvae were reared under controlled conditions at water temperatures of 28°C and 31°C during a 15-day period. Feeding with exclusively live Artemia nauplii gave best results, irrespective of rearing temperature (total length 13·6mm; average weight 31 mg; survival rate 83–85%). High survival rates of 81–88% were found also in all groups fed mixed diets, whereas growth rate of tench larvae was significantly influenced by the frequency of supplemental feeding with Artemia. When applied alone, the tested carp starter feed turned out to be insufficient for rearing the larval tench.     

Effect of salinity on occurrence of notochord deformities in Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> larvae

One of the difficulties to rear Anguilla japonica larvae is the frequent occurrence of notochord deformities. We tested the effect of salinity on the occurrence of the deformities, because we have been using 50 % diluted seawater (50 % SW) for glass eel production, on the basis of the fact that intermediate salinity saves energy due to lower cost for osmoregulation and contributes higher survival and growth rates. We reared 6-day-old larvae in 50 and 100 % SW for 85 days and observed their morphology. The occurrence rate of deformed larvae, including kyphosis and scoliosis, was significantly higher in 50 % SW (35.8 %) than in 100 % SW (25.4 %), while survival rate was significantly higher in 50 % SW (69.8 %) than in 100 % SW (32.3 %) and growth in 50 % SW (mean body depth: 7.9 ± 5.3 mm) was better than in 100 % SW (6.8 ± 4.6 mm). We speculate that the most of severely deformed larvae could not survive in the tougher condition of 100 % SW, showing the lower occurrence of deformed larvae. Eventually, the yield of normal larvae after 85 days rearing was 1.9-fold higher in 50 % SW than in 100 % SW, implying that the advantage of 50 % SW for rearing eel larvae outweighs the risk of deformities.     

Breeding and larval rearing of the camouflage grouper Epinephelus polyphekadion (Bleeker) in the hypersaline waters of the Red Sea coast of Saudi Arabia

This is the first report on the successful year-round natural spawning and larval rearing of Epinephelus polyphekadion (Bleeker) in captivity and under hypersaline water conditions of 42-43%₀ salinity in the Red Sea coast of Saudi Arabia. Although the fish spawned naturally once or twice a year during 1992-94 culture period, incorporation of cod-liver oil in the broodstock diet during the 1995 culture period enabled the fish to spawn continuously for 2-3 days in each month during March, April, May and August. The egg fertilization and hatching rates also increased during the 1995 spawning period. The egg fertilization rate varied from 90 to 100% with a mean of 96.5 ± 3.38%. The egg hatching rate varied from 70 to 95% with a mean of 83.1 ± 10.12%. The fertilized egg diameter averaged 757.3 ± 37.36 μm. There was a linear relation between the fertilized egg size and the egg hatching rate. The increase in the hatching rate relevant to the egg size was statistically significant (P < 0.01). The egg development time until hatching lasted for 19 h at 29°C. The newly hatched larval size ranged from 1.55-1.71 mm with a mean of 1.65 ± 0.052 mm in total length. The larval growth was slow in the early stages and the growth curve until metamorphosis showed a curvilinear pattern. Wide variations in larval size, range 22-47 mm with a mean of 33.40 ± 7.01 mm, were observed during the metamorphosis stage at day 50. No significant difference (P > 0.05) in growth and survival was observed between the larvae reared using white and grey coloured tanks. The larval survival up to metamorphosis was 1.6-4.7% with a mean of 2.98 ± 1.56% in the grey coloured tanks and 1.6-1.9% with a mean of 1.73 ± 0.16% in the white tanks. The results demonstrated the possibility of breeding E. polyphekadion under captive culture conditions. However, methods to improve the larval survival have to be pursued further for commercial farming of this species.     

Egg drift and hatching success in European river lamprey Lampetra fluviatilis: is egg deposition in gravel vital to spawning success?

相似文献   

Effects of a superoptimal temperature on aquacultured yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis>

This study aimed to investigate the effects of a superoptimal temperature on growth, body composition, body size heterogeneity, and relationships among these factors in juvenile yellowtail. Fish (mean body weight?=?24 g) were tagged individually and reared for 70 days under two different water temperature regimes [optimal (25 °C) and superoptimal (30 °C)]. After rearing, fish reared at 30 °C showed lower survival, less food, feed and protein utilization, significantly lower growth performance, and a lower hepatosomatic index than fish raised at 25 °C. Variations in body indices among individuals were larger for fish reared at 30 °C than for fish reared at 25 °C. Mean whole body protein content was significantly lower in fish reared at 30 °C than fish reared at 25 °C. In addition, several glucogenic and/or aromatic amino acids were lower in fish reared at 30 °C than in fish reared at 25 °C. Whole body lipid levels tended to be lower in fish with lower body weight reared at 30 °C. These results suggest that fish raised at 30 °C will have lower growth performance, and lower concentrations of specific amino acids. Moreover, heterogeneity in body size and body lipid content is expanded by a superoptimal temperature.     

Natural spawning,embryonic and larval development of F2 hybrid grouper,tiger grouper Epinephelus fuscoguttatus × giant grouper E. lanceolatus

This study aims to reveal the first report of the natural spawning of F1 hybrid grouper (TGGG), a crossbreed between the tiger grouper, Epinephelus fuscoguttatus × giant grouper, E. lanceolatus, since its first production in 2006. This marks the completion of its full cycle after a 10-year period. In order to establish a seed rearing protocol for a novel F2 hybrid TGGG, natural spawning, embryonic and larval developments were thoroughly observed. Five batches of natural spawning were recorded with an average of 1.50–15.3 kg eggs collected, while fertilization and hatching rates were recorded at 85.3–97.6%, and 63.0–98.3%, respectively. F2 larvae hatched out at 17:50 hours with an average body size of 1.74 ± 0.01 mm, and a yolk sac volume of 0.85 ± 0.197 mm3. The first feeding was initiated 3 days after hatching, which coincided with the onset of functional feeding apparatus and active swimming behavior. Larval dorsal and pelvic spines were formed at 6 days AH coupled with dynamic feeding activity, as more food was found in the digestive tract. Meanwhile, the F2 hybrid grouper shifted habitat from pelagic to benthic as early as 25 days AH, and entered a juvenile stage at 35 days AH, attaining a skin coloration similar to that of the F1 juvenile. This study concluded that naturally spawned eggs of F2 hybrid TGGG were exceptionally high in quality, although larvae were small and fragile, and performed vigorous feeding activities and cannibalistic behavior. Thus, these findings can serve as primary data to further develop the optimal rearing protocol to enhance the overall rearing performance.     

Histological study of the gastrointestinal tract in longfin yellowtail (<Emphasis Type="Italic">Seriola rivoliana</Emphasis>) larvae

This work contributes basic knowledge on larval development of Seriola rivoliana. A histological study describes the development of the digestive tract and accessory glands in S. rivoliana larvae reared under laboratory conditions at 24 °C from hatching to 30 days post-hatching (DPH). At hatching (2.6 ± 0.12 mm), larvae had an undifferentiated digestive tract with a closed straight tube and a large yolk sac with an oil globule. The liver and pancreas were observed at 1 and 2 days, and the mouth and anus opened at day 2. Enriched rotifers were visible in their digestive tract. At the beginning of the pre-flexion stage, a mixed nutritional period was observed. At day 3, exogenous feeding began; the digestive tract became differentiated into the buccopharynx, esophagus, an undifferentiated stomach, and the intestines. Zymogen granules were visible in the exocrine pancreas. At day 4, supranuclear vacuoles were present in the posterior intestine, indicating the beginning of intracellular digestion. At day 5, goblet cells were present in the esophagus and became functional at day 7 in the esophagus and intestine. The buccopharynx goblet cells developed at day 15. The presence of gastric glands and differentiation of the stomach in the fundic, cardiac, and pyloric regions during the post-flexion stage occurred at day 20. This was the onset of the juvenile period and the beginning of weaning; however, a long co-feeding phase is recommended. Pyloric caeca were observed at day 30 (13.6 ± 1.6 mm). These results provide valuable information on S. rivoliana larvae biology and digestive physiology, which should be useful to improve cultivation techniques and identify ecological features involved in ontogeny.     

Optimum low salinity to reduce cannibalism and improve survival of the larvae of freshwater African catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

The freshwater African catfish Clarias gariepinus is carnivorous and cannibalistic even during the larval and juvenile stages and this behavior causes economic losses in aquaculture. This study examined for the first time the effect of salinity on cannibalism, survival, and growth of African catfish larvae in the hatchery. Larvae (4 days old, median 7.8 mm TL, 2.8 mg BW) of the African catfish were reared for 21 days at nominal salinity 0, 1, 2, 3, 4, 5, 6, and 7 ppt. After 21 days, they grew to 10–39 mm (median 22 mm) and 10–490 mg (median 90 mg), with no significant difference by salinity treatments. Survival ratios were similarly low (24–31%) at 0, 1, 3, and 7 ppt and significantly higher (49–55%) at 2, 4, 5, and 6 ppt. Cannibalism was significantly lower, 15–30% at 4–6 ppt, than the 40–50% at 0–3 and 7 ppt. Size variation was lower at 4–6 ppt and higher at 0–3 and 7 ppt. We recommend hatchery rearing of African catfish at the optimum low salinity of 4–6 ppt rather than in full fresh water at least up to 21 days. This rearing method fosters larval welfare and improves hatchery production.     

The effect of live feeds bathed with the red seaweed <Emphasis Type="Italic">Asparagopsis armata</Emphasis> on the survival,growth and physiology status of <Emphasis Type="Italic">Sparus aurata</Emphasis> larvae

Larval rearing is affected by a wide range of microorganisms that thrive in larviculture systems. Some seaweed species have metabolites capable of reducing the bacterial load. However, no studies have yet tested whether including seaweed metabolites on larval rearing systems has any effects on the larvae development. This work assessed the development of Sparus aurata larvae fed preys treated with an Asparagopsis armata product. Live prey, Brachionus spp. and Artemia sp., were immersed in a solution containing 0.5% of a commercial extract of A. armata (Ysaline 100, YSA) for 30 min, before being fed to seabream larvae (n = 4 each). In the control, the live feed was immersed in clear water. Larval parameters such as growth, survival, digestive capacity (structural-histology and functional-enzymatic activity), stress level (cortisol content), non-specific immune response (lysozyme activity), anti-bacterial activity (disc-diffusion assay) and microbiota quantification (fish larvae gut and rearing water) were monitored. Fish larvae digestive capacity, stress level and non-specific immune response were not affected by the use of YSA. The number of Vibrionaceae was significantly reduced both in water and larval gut when using YSA. Growth was enhanced for YSA treatment, but higher mortality was also observed, especially until 10 days after hatching (DAH). The mortality peak observed at 8 DAH for both treatments, but higher for YSA, indicates larval higher susceptibility at this development stage, suggesting that lower concentrations of YSA should be used until 10 DAH. The application of YSA after 10 DAH onwards promotes a safer rearing environment.     

Residence pattern of the ayu <Emphasis Type="Italic">Plecoglossus altivelis</Emphasis><Emphasis Type="Italic">altivelis</Emphasis> larvae and juveniles occurring in the surf zone of a sandy beach,Niigata Prefecture,northern Sea of Japan

This study examined the residence pattern of ayu larvae and juveniles occurring in the surf zone of an extensive sandy beach, in the north part of the Sea of Japan. In this region, ayu larvae mainly hatched in October and November, generally appeared in the surf zone in hatching order, and were continuously present until the following January. During a short period after mid- to late January when the water temperature fell below 10°C, ayu larvae and juveniles concurrently migrated from the surf zone regardless of their size and age, resulting in a longer term residence for earlier-hatched ayu. This was in contrast to studies in other waters, which found that early-hatched ayu have a short-term residence and late-hatched a long-term residence. Furthermore, faster growth that enables ayu to reach the maximum residence size (around 40 mm BL) in the surf zone during the period when the water temperature was still over 10°C might lead to earlier migration and a shorter residence term. This process might be applicable only to the early-hatched group (defined as individuals hatched in late September and October) and depends on the size of each individual, thus leading to a gradual migration of larger individuals as they attain maximum residence size.     

Rearing temperature affects Senegalese sole (Solea senegalensis) larvae protein metabolic capacity

The present work examined the short- and long-term effects of three rearing temperatures on protein metabolism and growth trajectories of Senegalese sole larvae using ¹⁴C-labelled Artemia protein as feed. A first feeding trial was performed on larvae reared at 15, 18 and 21 °C (at 26, 17 and 14 days post-hatching (dph), respectively) and a second trial conducted on post-larvae after transfer to the same rearing temperature (~20 °C) (49, 35 and 27 dph, in larvae initially reared at 15, 18 and 21 °C, respectively). Temperature greatly influenced larvae relative growth rate (RGR) and survival, since growth at 15 °C was severely depressed. Protein digestibility and retention was highest at 18 °C during the first trial (85.35 ± 1.16 and 86.34 ± 2.33 %, respectively). However, during the second trial, post-larvae from 15 °C had the highest feed intake and protein digestibility (3.58 ± 1.54 and 75.50 ± 1.35 %, respectively), although retention was similar between treatments. Furthermore, after transfer to 20 °C larvae from 15 °C experienced compensatory growth, which was observed until 121 dph, and confirmed by RGR values, which were significantly higher at 15 ºC than at 21 ºC or 18 ºC. Results from the present study show that Solea senegalensis larval development, survival and protein digestion and retention are highly affected by thermal history.