Search

The present experiment was conducted to evaluate the effects of trace mineral (Cu, Zn, Mn and Fe) premixes from inorganic and chelated (chelated to 2-hydroxy-4-methylthiobutanoic acid or hydroxy analog of methionine; Mintrex™, Novus International Inc., St. Charles, MO, USA) sources, in rockfish, (Sebastes schlegeli). fed diets containing mineral inhibitor phytic acid. Seven isonitrogenous (46% crude protein/CP) and isocaloric (16.63 KJ available energy per g diet) semi-purified diets comprising of a Basal control and diets supplemented either with the inorganic (I) or chelated premix (M) at three different levels of 0.75 (I0.75/M0.75), 1.5 (I1.5/M1.5) and 3 (I3/M3) g kg−1 diets were formulated. Twenty-four fish averaging individual wet body weight of 9 ± 0.2 g (Mean ± SD) were fed one of the experimental diets in quadratic group for 16 weeks. Average weight gain (WG) of fish fed M3 was significantly higher than that of fish fed Basal control and I1.5 diets (P

Six isonitrogenous (320 g kg−1) and isolipidic (60 g kg−1) diets were formulated with graded levels (0, 5, 10 and 15 g kg−1) of dicalcium phosphate (DCP) and fungal phytase (750 and 1500 FTU kg−1 diet). Tra catfish (Pangasianodon hypophthalmus), 9.6 g, were fed the diets for 12 weeks. Each experimental diet was fed to eight replicates of fish to apparent satiation. At the end of the trial, fish fed the diets containing 15 g kg−1 DCP, 750 and 1500 FTU kg−1 phytase had higher growth performances, protein efficiency ratio and phosphorus retention than those fed the control diet, 5 g kg−1 DCP and 10 g kg−1 DCP diets (P

The microbial community in minimal-exchange, superintensive culture systems should be managed to cycle nutrients and enhance production. This paper explores the effects of biofloc concentration reduction and a fish-free diet on several microbial community characteristics. In 16, 3.5-m diameter, 71-cm deep outdoor tanks, shrimp were stocked at 460/m3. Eight of the tanks received a fish-free, plant-based feed and eight received a conventional feed containing fishmeal and fish oil. Within each diet type, biofloc concentration was reduced in four of the tanks and was not reduced in the other four tanks. Photosynthetically active radiation (PAR) extinction coefficients, photosynthetic oxygen production, chlorophyll-a (chl-a) concentrations, pheophytin-a (pheo-a) concentrations, and the sum of odd and branched chain fatty acid concentrations as a bacterial abundance indicator (BAI) were measured. Biofloc reduction significantly (P≤ 0.003) decreased PAR extinction coefficients, chl-a concentration, pheo-a concentration, and BAI concentration, while significantly increasing photosynthetic oxygen production. Diet did not significantly affect (P > 0.05) any of these measured parameters. The observed changes in microbial community characteristics corresponded with, and may help to explain, significantly improved shrimp feed conversion ratios, growth rate, final weight, and biomass yield in the tanks with biofloc reduction.

The present study was conducted to determine the safe and toxic levels of dietary copper in juvenile olive flounder, Paralichthys olivaceus, fed Mintrex® copper, a chelated dietary copper source. Fish averaging 3.8 ± 0.13 g (mean ± SD) were fed 1 of 10 diets (n = 3) containing 7 (Cu0), 10.4 (CuM5), 15.8 (CuM10), 24.9 (CuM20), 43.4 (CuM40), 82.1 (CuM80), 158 (CuM160), 308 (CuM320), 658 (CuM640), and 1267 (CuM1280) mg Cu/kg diet. At the end of 12 wk of feeding trial, weight gain (WG), specific growth rate, and protein efficiency ratio of fish fed CuM5 and CuM10 diets were significantly higher than those fed CuM80, CuM160, CuM320, CuM640, and CuM1280 diets (P < 0.05). Survival of fish fed Cu0, CuM5, CuM10, CuM20, and CuM40 diets was significantly higher than those of fish fed CuM320, CuM640, and CuM1280 diets. Whole-body lipid content of fish decreased while whole-body ash increased with dietary copper levels. Whole-body and tissue copper concentrations increased with dietary copper levels. Although ANOVA test suggested that the toxic level of dietary Cu in juvenile olive flounder, P. olivaceus, could be 320 mg/kg diet, broken-line analysis of WG indicated a level of 286 mg/kg diet when Mintrex®Cu is used as the dietary copper source.

In minimal-exchange, superintensive culture systems, the flocculated (biofloc) particles that accumulate may provide benefits for cultured shrimp; however, excessive particle accumulation can hinder shrimp performance. Also, the shrimp aquaculture industry is reliant on marine fish-based feeds. Using these products can lead to exploitation of marine resources, the introduction of contaminants to cultured shrimp, and unstable production costs. This study examined the use of simple, side-stream settling chambers as a means of controlling the abundance of particles in the water column and demonstrated the effects on water quality and shrimp production. The study also compared water quality and shrimp production parameters between a commercial, fish-based diet and a diet formulated almost entirely from vegetarian components, with expelled soybean meal as its principle protein source. The fish-based diet and the plant-based diet each contained 35.7% and 36.4% crude protein and 11.0% and 10.8% total lipid, respectively. The experiment was conducted in 3.35 m diameter, outdoor tanks, shrimp were stocked at 460 m − 3 and grown for 12 weeks. By the end of the experiment, settling chambers had removed 59% of suspended solids, decreased turbidity by 57%, reduced nitrate–nitrogen concentration by 60%, reduced phosphate concentration by 61%, and caused a 33% increase in alkalinity, all highly significant effects. Settling chambers also contributed to significantly improved shrimp feed conversion ratio, biomass, growth rate, and final weight ( P = 0.002, 0.006, − 3 ) was 41% greater in treatments with solids management than those without. Shrimp survival was not statistically different with or without settling chambers. Water quality parameters were not statistically different between the two diet types, except phosphate concentration which, by the end of the experiment, was 34% lower in the tanks receiving the plant-based diet. Shrimp production parameters were not statistically different between the two diets. The study showed that controlling the concentration of particles in superintensive shrimp culture systems can significantly improve water quality and shrimp production. Also, an environmentally friendly and potentially economical plant-based diet can produce results comparable to a fish-based feed in superintensive shrimp culture systems.

Gross and net photosynthesis, and water column respiration of a super-intensive Litopenaeus vannamei raceway culture with zero water exchange were measured over 21 weeks using the light and dark bottle method. Spearman correlation analysis was used to explore the relationship of these parameters with other water quality parameters (O2, temperature, pH, alkalinity, TAN, NO2, NO3, dissolved orthophosphate, turbidity, TSS and VSS) and of shrimp performance based on growth rate and feed conversion rate. Net photosynthesis generally had negative values, indicating that the system was predominantly heterotrophic. Gross photosynthesis was significantly related only with VSS, and water column respiration was related only with turbidity. Shrimp growth rate increased with higher temperature and dropped with higher pH. Nitrite had a strong inverse relationship with shrimp growth rate (R2 = 0.8044, p

This work aimed at determining the dissolved oxygen consumption rate of Litopenaeus vannamei juveniles maintained in a microbial biofloc raceway system at high density with no aeration. Three 4 L bottles were filled for each treatment, sealed hermetically, and placed in an enclosed greenhouse raceway system. Four shrimp (13.2±1.42 g) were assigned to two sets of the bottles, which underwent the following treatments: light conditions with no shrimp; dark conditions with no shrimp; light conditions with shrimp; and dark conditions with shrimp. Dissolved oxygen content was measured every 10 min for 30 min. A quadratic behavior was observed in dissolved oxygen concentration over time. Significant differences for oxigen consumption were observed only at 10 and 20 min between shrimp maintained in the dark and those under light conditions. At 10 min, a higher value was observed in shrimp maintained under light, and at 20 min, in the dark. Significant differences between 10 and 20 min and between 10 and 30 min were observed when oxygen consumption was analyzed over time in the presence of light. Under dark conditions there were significant differences only between 20 and 30 min. Lethal oxygen concentration (0.65 mg L-1) would be reached in less than one hour either under light or dark conditions with no aeration.

Reproductive performance of unilateral eyestalk ablated and unablated wild and pond reared Penaeus semisulcatus was compared in a series of experiments in Eilat, Israel. Tagging techniques were used to study the maturation and spawning of individual females. The average numbers of spawns and eggs per ablated females were more than double those produced by unablated females, although fewer eggs per spawn were produced by ablated females. There were no significant differences in spawn quality, as measured by the percent fertility, hatch, and metamorphosis to zoea 1, between ablated and nonablated females. Egg production of ablated females was consistent for 70 to 80 days after which a decline was observed. The average rate of egg production of nonablated shrimp was more erratic with an apparent decline only after 100 to 110 days. No significant differences were found in spawn size or spawn quality between the first three spawns of ablated and nonablated females. A significant reduction in spawn size was apparent over the molt cycle although the percent fertility remained constant. Spermatophore transfer rates of 84 to 92% were achieved with female to male rations of 1.8:1 to 2.5:l. A reduction in fecundity was observed for successive generations of pond-reared brood stock. Eyestalk ablation was used to stimulate spawning of P. semisulcatus in captivity with no significant reduction in brood stock survival or in spawn quality.

Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium values were all significantly affected by salinity (as artificial sea salt) with values decreasing with decreasing salinity. These decreases were small, however, relative to decreases in salinity, indicating iono- and osmoregulation with adjustment for gradients. The hemolymph osmolality and sodium and calcium concentrations in shrimp exposed to either 2 g/L artificial sea salt or 2 g/L mixed-ion solution (a mixture of sodium, potassium, calcium, and magnesium chlorides that approximate the concentrations and ratios of these cations found in 2 g/L dilute seawater) did not differ significantly. However, hemolymph potassium levels were significantly lower in shrimp held in the mixed-ion environment. Potassium influx rates were similar in shrimp held in either artificial sea salt or mixed ions. The results of this study indicate that salinity affects hemolymph-cation concentrations and osmolality. Further, differential potassium-influx rates do not appear to be the basis for low hemolymph potassium levels observed in shrimp held in mixed-ion environments.

Zero water exchange, super-intensive culture of shrimp in enclosed raceway type systems can be considered environmentally friendly in that containment of water within the system prevents potential spread of disease between the wild populations and cultured animals and avoids nutrient rich waste from polluting coastal waters. However, as a relatively new strategy for shrimp production, there is much still to be learned about the potential biological and economic benefits of producing shrimp in suspended microbial floc based systems. Understanding shrimp feeding behavior and quantification of shrimp feed consumption provides valuable information for culturists to improve feed management, one of the keys to economic viability. The objective of this study was to evaluate the nutritional contribution of varying levels of microalgae/bacterial floc on survival, growth, food consumption, and FCR of Litopenaeus vannamei juveniles fed diets with different protein levels in replicated experimental microcosm tanks. The 20 day experiment evaluated 9 treatments, three water types fed three different protein diets. Water was recirculated within a sump and consisted of either clear, UV filtered water, water containing microbial floc from an adjacent zero exchange super-intensive raceway production unit, or a 50:50 mix of clear water and raceway water. Diet treatments were either no food, 25% or 35% protein content. Treatments were randomly assigned to 50 L, mesh covered plastic bins receiving each water type. Each treatment consisted of five replicates, each containing 44 shrimp, with a mean stocking weight of 1.82±0.71 g for a final density of 300 per m 2 . Shrimp in each treatment (except the no feed treatment) were fed 3 times daily via a specially designed feed tray. Food consumption and FCR were calculated based on weight gain, survival, total consumed feed, feed loss through leaching, and initial feed moisture content. Results were analyzed by two-way analysis of variance (ANOVA) and differences between the means analyzed by Tukey's test (α=0.05). Survival in the fed treatments was greater than 98% in all treatments (P>0.05). Survival in the non-fed treatments was significantly higher in the raceway water treatments than in the clear water treatment (P

Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.

Growth and production of Pacific white shrimp (Litopenaeus vannamei) was examined along with water quality, and general indicators of microbial activity in replicate intensive tank cultures with no sediment, sand sediment, and sand sediment together with additional vertical surfaces (sand/mat). All treatments received similar feed and fertilizer input. Initial linear shrimp growth rates was relatively high (1.65 g/week) in all treatments. A reduction in growth rates was seen in the no-sediment and sand treatments, while linear growth continued longer in the sand/mat treatment. Shrimp weight, survival and production was significantly greater in the sand/mat treatment than in the sand and no-sediment treatments. While the latter two treatments yielded similar production, the no-sediment treatment required weekly additions of soda ash during the last month of the 104-day season to maintain a minimum pH of 7.0. Significantly higher pH, in conjunction with lower phytoplankton biomass and ammonia in the sand/mat treatment than in the sand treatment suggests greater carbon fixation by the attached algal community of the sand/mat treatment. This is further supported by similar carbon mineralization rates in all treatments as roughly indicated by water respiration rates in conjunction with greater sludge accumulation in the sand/mat treatment. Phyto and bacterioplankton levels were significantly lower in the sand/mat treatment than in the other treatments. Ammonia, nitrate and sludge accumulation were similar in the no-sediment and sand tanks. The sand/mat treatment had significantly greater nitrite than the other treatments. Water column nitrification rates were similar in the sand and no-sediment treatments and significantly greater in the sand/mat treatment, suggesting that nutrient cycling rates may be greater in this treatment. From a production standpoint, the primary difference in the no-sediment and sand treatments was the need for proactive management of pH in the no-sediment tanks. The quantity of vertical surface area addition tested in the sand/mat treatment of this study yielded higher shrimp production in conjunction with significant differences in water quality and indicators of general activity, suggesting that this relatively high level of vertical surface addition may significantly affect aquaculture production systems.

Plankton community establishment and shrimp production in a prototype biosecure pond were compared to three control ponds. The biosecure pond was enclosed and intake water was disinfected, while control ponds were neither enclosed nor disinfected. All ponds were managed with no water exchange and stocked with 100 postlarvae/m2, Litopenaeus vannamei. Residual oxidant concentrations in the biosecure pond dropped rapidly after cessation of chlorinated water addition. This was followed by a sharp increase in water column bacterial abundance, after which the pond was fertilized and inoculated with cultured Chaetocerous gracilis. After crash of the initial C. gracilis bloom in the biosecure pond, this species was not observed again. Following initial large fluctuations in biosecure pond bacterial abundance, phytoplankton biomass, oxygen consumption and nitrification rates, these parameters appeared to stabilize at levels similar to the control ponds. Early season compositional differences in phytoplankton, zooplankton, and bacterial communities were observed. No differences were seen in late-season phytoplankton and bacteria; however, zooplankton biomass tended to be lower in the biosecure pond than in the control ponds throughout the season. Shrimp production in all ponds was greater than 9,000 kg/ha. Production in the single biosecure pond was not a significant outlier compared to production in the triplicate control ponds.

The culture of Pacific white shrimp Penaeus vannamei (PVA) within the geographical range of Atlantic white shrimp P. setiferus (PSE) has prompted concern regarding potential ecological risks. The present study evaluates the potential for spontaneous hybridization between these closely related litopenaeid species. Prezygotic barriers to hybridization were evaluated utilizing quantitative analysis of behavioral interactions associated with mating, artificial insemination, and a novel in vitro fertilization technique. There was a significant decrease in the number of interspecific behavioral interactions (P < 0.005). In total, 15 ♀ PSE × ♂PSE and 11 ♀PVA × ♂PVA matings were achieved. No spontaneous matings were observed between species. In artificial insemination trials, 60% of the intraspecific inseminations were fertile with mean fertilization rates of 9.21 ± 3.83% for PSE and 11.6 ± 5.2% for PVA. No interspecific crosses were fertile. This study documents in vitro fertilization for the first time in two litopenaeid species. In vitro fertilization was achieved by upwelling a concentrated sperm suspension under a spawning female. Three levels of negative controls were used to eliminate the possibility of contamination. Fertilization was achieved in 13 of 14 intraspecific trials with mean fertilization rates of 2.48 ± 0.57% for PSE and 3.88 ± 1.34% for PVA. No interspecific crosses were fertile. Based on the low levels of behavioral interaction during interspecific crosses, the lack of natural interspecific matings, and absence of fertilization in interspecific crosses for both artificial inseminations and in vitro fertilizations, the potential for hybridization between P. setiferus and P. vannamei appears to be negligible.

Conventional maturation systems for open thelycum penaeid shrimp are typified by 3.5-4.5 m diameter tanks stocked at three to seven shrimp/m2 at a 1:1 sex ratio. A system based on maturation in female unisex tanks and transfer to male tanks for mating offers opportunities for development of improved experimental systems, increased efficiency in commercial systems and decreased production costs. This type of unisex system was implemented in the present study, and three maturation laboratory management techniques, including ultraviolet water treatment, vinyl tank liners, and male eyestalk ablation were tested for effects on the reproductive performance of Penaeus setiferus. Little or no differences were found among tested parameters, and consistent mating and fertilized spawns were achieved in all treatments. The use of unisex culture tanks and transfer of mature females to all male tanks for mating was found to produce a level of mating similar to that in the conventional tanks. Overall, a pooled average o...

Two pond experiments were conducted at the Waddell Mariculture Center to compare production characteristics of the native Penaeus setiferus and Pacific P. vannamei white shrimp in South Carolina. In 1985, 7–9 day old postlarval P. setiferus were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1, one 0.25, and one 0.5 ha ponds. Both species were stocked at 12 shrimp/m2. The shrimp were fed a 25% protein commercial food and harvested by draining after 147 d. Sarvival in all ponds was > go%, but growth and production of the P. setiferus were considerably lower than values obtained for P. vannamei: 12.8 g and 1,555 kg/ha/crop for P. satiferus versus 19.7 g and 2,477 kg/ha/crop for P. vannamei. In 1989, duplicate 0.1 ha ponds were stocked with P. setiferus and P. vannamei at 60 shrimp/m2, and two additional 0.1 ha ponds were stocked with P. setiferus at 40/m2. The P. setiferus postlarvae were produced at the Waddell Center from captive-reared and wild South Carolina brood stock. Rearing procedures involved paddlewheel aeration (10 hp/ha), regular water exchange (averaging 16–21%/d in all ponds), and use of a 40% protein feed. Due to the availability of postlarvae, the various treatments were stocked at different times. Both P. setiferus treatments were reared for 145 d, while the P. vannamei were reared for 165 d. P. setiferus at the 40/m2 density attained mean size, survival, and standing crop biomass at harvest of 13.5 g, 97.5% and 5,259 kg/ha/crop, respectively. The 60/m2P. setiferus treatment was stocked 2 wk earlier and yielded 15.2 g mean weight, 87.5% survival, and 7,995 kg/ha/crop at harvest. The P. vannamei 60/m2 treatment, which was stocked 3 wk earlier than any of the P. setiferus, produced mean size, survival and standing crop biomass at harvest of 17.1 g, 69.5% and 7,187 kg/ha/crop. Both survival and production levels would have been higher had not one replicate experienced a partial mortality due to a feeding accident. The 1989 study yielded what is thought to be the highest production levels yet achieved with P. setiferus in pond culture. These results suggest that P. setiferus may be a viable alternative to P. vannamei for intensive cultivation in the continental U.S. when P. vannamei are unavailable. Further evaluation of this potential is needed.

Producers and researchers have long suspected correlations between "runt deformity syndrome" (RDS), morphological anomalies, poor production, and viral infection for various penaeid shrimp species. Unfortunately, evidence has been circumstantial and little research has been focused on defining harvest size distributions as it relates to viral histopathology. The present study highlights these elements, in a factorial experimental design, using increased stocking density (60/m2 and 100/m2) and decreased water exchange (100%, 50%, and 10% per day) as factors. Twelve 29.2-m2 tanks were stocked with suspected IHHNV-infected Penaeus vannamei postlarvae from a Central American hatchery, and were harvested after 164 days. Low dissolved oxygen levels resulted in poor survival (43.5% and 53.6%) in tanks which were stocked at 100/m2 and limited to 10% water exchange per day. Density and water exchange regimes had little effect on water quality, survival, or growth in other experimental groups. A "runt deformity syndrome" and other physical anomalies are described and the former is correlated with increased incidence of IHHNV associated Cowdry type A inclusion bodies in 4 organ systems. A trend toward decreasing incidence of inclusion bodies was found as exchange rates were increased from 50% to 100% per day. Distributions of size at harvest indicate less skewness and kurtosis as well as lower incidence of deformities in low survival tanks, suggesting increased mortality of more severely infected RDS shrimp.

Determination of the proper level of supplemental aeration in intensive shrimp culture is critical for maintaining adequate concentrations of dissolved oxygen while minimizing equipment and operating costs. Little quantitative information is available on sizing the amount of aeration equipment to various levels of intensification. Results indicate that dawn dissolved oxygen (mg/liter) can be predicted based upon the amount of feed applied (kg/ha day) per unit aeration (hpday/ha). The amount of feed which can be applied with a given amount of supplemental aeration and a reasonable expectation that dawn dissolved oxygen will not be below a targeted concentration is expressed by the equation F A = 28·83 − (4·31 × DO ) .

A controlled comparison of the reproductive performance of individually tagged wild (P0) and first generation pond-reared (P1) Penaeus semisulcatus is presented. Eyestalk ablated and nonablated females matured and spawned in 3-m 3 maturation tanks. Females which had undergone unilateral eyestalk ablation showed: (1) a slower growth rate (g/day); (2) a trend towards shortening of the molt cycle; (3) a significantly smaller number of eggs and nauplii per spawn; and (4) significantly increassed spawn frequency and increased rate of egg and nauplii production. The fertility and hatchability of spawns from ablated females were not different from those of spawns from nonablated females. All of these trends were observed for both P0 and P1 spawners. The average spawn from a P1 female had fewer eggs than the average spawn from a P0 female. Fertility and hatchability of spawns from both generations were variable and no significant difference was found in the number of nauplii in an average spawn. No significant differences were found between the two generations in the average number of spawns, eggs and nauplii produced per day. Thus the reproductive potential of P1 broodstock was not different from that of P0 females induced to mature and spawn in captivity.