bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Shelter, Broodstock Number, and Sex‐Ratio on Juvenile Production in the Swordtail Xiphophorus helleri under Intensive Culture Conditions
Authors: Jones C. L. W. , Kaiser H. , Hecht T
Published: April 2007

Abstract.— Filial cannibalism has been identified as a constraint to the intensive production of swordtails Xiphophorus helleri. The objective of this study was to quantify the effect of refuge availability and quantity, broodstock population density, and adult sex‐ratio on the rate of cannibalism under culture conditions. The availability of shelter had a significant effect on the number of harvestable juveniles, while the quantity of shelter did not affect harvest size. At a constant sex‐ratio of 1:1 and broodstock population densities of four, ten, and 16 fish per 300‐L tank the amount of juveniles harvested was lowest at the stocking density of four fish per tank, but did not increase significantly when stocking density was raised from ten to 16 fish per tank. Rate of cannibalism was lowest at the lowest population density. At a constant stocking density of ten fish per tank and sex‐ratios of 1:1, 1:4, and 4:1 (male: female), the highest number of juveniles was obtained at a social structure of two males and eight females. Rate of cannibalism was independent of sex‐ratio, indicating that males and females are equally cannibalistic. These results suggest that the 300‐L broodstock tanks should be stocked with a maximum of two males and between five and eight females to obtain the greatest number of harvestable juveniles per tank.
A Digestion Procedure for the Simultaneous Determination of Total Nitrogen and Total Phosphorus in Pond Water
Authors: Gross Amit , Boyd Claude E.
Published: April 2007

Abstract— Total phosphorus and total nitrogen often are measured in studies of pond water quality. A laboratory study was conducted to test a digestion procedure for the simultaneous determination of total nitrogen and total phosphorus in pond water. Seventy water samples were collected from channel catfish ponds. Samples were digested in two ways. One digestion followed the standard protocol of persulfate digestion in an acidic environment for total phosphorus analysis, and total phosphorus was then measured with the ascorbic acid procedure. The second digestion was done by the procedure used for determining total nitrogen which involves persulfate digestion in an alkaline environment. The total nitrogen digestion procedure followed by phosphorus determination provided results similar to those obtained in the standard persulfate digestion for phosphorus. The slope of the regression line did not differ from 1.0 (P < 0.05) and the Y intercept did not differ from 0 (P < 0.05). Spike recovery averaged 99.1% (range 85–112%) in the total nitrogen digestion procedure; it averaged 98.4% (range 88–113%) in the standard total phosphorus digestion. The results of this investigation indicated that a single digestion can be used to obtain a digest suitable for measurements of total nitrogen and total phosphorus.
Preliminary Studies of Artificial Spawning of Channel Catfish as Male‐Female Pairs or All‐Female Groups in Recirculating Systems
Authors: Bates Mark C. , Tiersch Terrence R.
Published: April 2007

Abstract— Channel catfish Icralurus punctatus are commonly spawned for research purposes by pairing of a hormonally treated female with a male in flow‐through aquaria. A technique that allows hormonal induction of ovulation in females without pairing would accelerate genetic improvement and production of hybrid catfish. Over a 3‐yr period (1994, 1995, and 1996) we conducted a series of trials to demonstrate the potential for artificial spawning in recirculating systems, and in 1996 we included trials with grouped females in addition to male‐female pairs. Females were induced to spawn with injection of synthetic leuteinizing hormone‐releasing hormone, and those that ovulated were stripped and the eggs were artificially fertilized. During 1994 and 1995, all fish were spawned by pairing, and in 1996, half of the females were spawned by pairing and half were grouped in tanks without males. Spawning success (percent of females that produced eggs), latency (time between injection and ovulation), and percent fertilization were observed for the paired and grouped trials. Spawning success was 36% in 1994 (N= 36). 22% in 1995 (N= 54). 41% in 1996 (N= 27). and 58% for grouped females (N= 26). The latency period was 113 ± 69 h in 1994, 109 ± 57 h in 1995, 44 ± 8 h in 1996, and 50 ± 9 h for grouped females. Percent fertilization was 16 ± 26% for eggs stripped in 1994, 72 ± 25% in 1995, 43 ± 20% in 1996, and 16 ± 37% for grouped females. In 1995, water quality problems were associated with high mortality of females (24 of 44 females; 4 of 44 males). The metabolic demands of final oocyte maturation in combination with methemoglobinemia caused by high nitrite levels could account for the increased vulnerability of females. These trials indicate that with adequate biofiltration, artificial spawning is possible in recirculating systems and with females grouped rather than paired. Further research on hormone dosage and timing of egg stripping will increase the utility of grouped spawning of channel catfish.
Production of Australian Red Claw Cherax quudricarinatus in Polyculture with Nile Tilapia Oreochromis niloticus
Authors: Rouse David B. , Kahn Bruce M.
Published: April 2007

Abstract— Australian red claw crayfish Cherax quudricarinurus were cultured in monoculture and in polyculture with male Nile tilapia Oreochromis niloricus in nine 0.02‐ha earthen ponds. Red claw with an average weight of 7 g were stocked in all ponds at 2/ m2. Tilapia with an average weight of 19 g were stocked in six ponds at either 0.5 or 1/m2. A sinking 32% fish diet and dry alfalfa hay was provided to all ponds as feed and forage. After 135 d, red claw survival was similar (19–24%) in all treatments while average weights were 76 g in monoculture and 48 g in both polyculture treatments. Lower than expected survival was a result of stress caused by poor shipping conditions. Tilapia survivals were similar (84–90%) in all ponds and had an average weight of 403 g when stocked at 1/m2 and 444 g when stocked at 0.5/m2. Red claws are generally considered non‐aggressive, especially when compared with other clawed crustaceans. This lack of aggressiveness is suggested as a cause for decreased growth in polyculture with tilapia.
Comparison of Artificial and Natural, New and Reused, Brackish Water for the Larviculture of the Freshwater Prawn Macrobrachiurn rosenbergii in a Recirculating System
Authors: Mallasen Margarete , Valenti Wagner Cotroni
Published: April 2007

Abstract— Differences in culture duration, metamorphosis rate and the productivity in hatchery culture of M. rosenbergii using a closed system with natural and artificial brackish water were evaluated. Reuse of brackish water in more than one hatchery cycle was also evaluated. Natural and artificial brackish water constituted the two tested treatments, which were distributed in four independent recirculating systems (tank and respective biofilter). Four batches of cultures were conducted and the 2nd and 4th reused the water from the 1st and 3rd. respectively. Mean duration of the hatchery period was 28 d in natural brackish water and 31 d in artificial brackish water. The metamorphosis rate and the average productivity for the natural brackish water treatment were 74% and 60 postlarvael l, respectively, and values obtained with artificial brackish water were 55% and 44 postlarvae/L. The successful hatchery culture of M. rosenbergii in this specific artificial brackish water suggests its potential use in enterprises located far from the coast. Brackish water can be used in two consecutive cultures without a negative effect on productivity.
Effect of Dietary Phospholipids on Digestion of Neutral Lipid by the Prawn Penaeus monodon
Authors: Glencross Brett D. , Smith David M. , Williams Kevin C.
Published: April 2007

Abstract— Different amounts of dietary phospholipid were tested for their effect on the digestibility of total neutral lipids in the diet of the prawn Penaeus monodon. A purified source of the phospholipid, L‐α‐phosphatidylcholine, was included at 0. 5, 10, 20 or 40 g/kg in a purified diet containing 80 g/kg olive oil as the predominant neutral lipid source. The apparent digestibility of the neutral lipid (ADNL) in these diets was determined by comparing concentrations of the digestibility marker, cholestane in the feed and faeces of the prawns. ADNL (%) increased curvilinearly with increasing dietary phospholipid content (X, %) as described by the equation: ADNL = 80.4 + 9.08X ‐1.705X2 (P < 0.05; R2= 0.71); the asymptote of 92.5% was achieved with a phosphatidylcholine value of 27 g/kg. These results demonstrate that phosphatidylcholine significantly increases the digestibility of neutral lipids by penaeid prawns. However, olive oil was used as the predominant neutral lipid source to examine the effects with a relatively poorly digestible lipid source. The effects of phosphatidylcholine on more readily digested lipid sources such as fish oils, may not be as great, but still be sufficient to improve the utilisation of these nutrients.
Growth, Yield, Dressout, and Net Returns of Bighead Carp Hypophthalmichthys nobilis Stocked at Three Densities in Catfish Ictalurus punctatus Ponds
Authors: Engle Carole R. , Brown David
Published: April 2007

Abstract— Alternative fish species that can be cultured together with catfish Ictalurus punctatus provide an opportunity to diversify caffish farms. A 2‐yr study was conducted in 0.10‐ha earthen ponds to evaluate the effect of bighead carp (BHC) stocking density on growth, yield, dressout yield, and net returns. Initially, bighead carp (average weight of 22 g) were stocked at rates of 380, 750, or 1,130 fishha in ponds with catfish. Caffish were cultured under commercial conditions by stocking caffish at a density of 12,500/ha, aerating nightly and feeding at an average rate of 82 kgha per d. Stocking rates for 2‐yr‐old fish were reduced to 77, 260, and 435/ha in the second growing season. There were no significant differences among treatments (P > 0.05) in summer growth of bighead carp in either year. Bighead carp stocked at 1,130 fishha had significantly higher yields than those stocked at 380/ha, but did not reach minimum market size of 2.2 kg during the first year (P > 0.05). There were no significant differences (P > 0.05) in caffish growth, yield, survival, or feed conversion ratios due to the bighead carp stocking densities. Partial budget analysis indicated that net benefits were positive for all three treatments over a range of prevailing prices of bighead carp. Bighead carp production in catfish ponds is economically feasible over a wide range of prices. Given the market risk of producing smaller fish at the higher density, the medium density is the preferred stocking density of fingerling bighead carp in catfish ponds.
Effects of Food and Temperature on Survival and Development in the Peppermint Shrimp Lysmata wurdemanni
Authors: Zhang Dong , Lin Junda , Creswell R. LeRoy
Published: April 2007

Abstract— The effects of four kinds of foods (Artemia nauplii, rotifer, and microalgae Chaetoceros gracilis and Isochrysis galbana) and four temperature regimes on survival and development of larval Lysmata wurdemanni, a marine ornamental shrimp, were determined. The larvae fed with Chaetoceros or Isochrysis only survived for a maximum of 17 d, before developing to zoea IV. The survivorship of the larvae fed with Artemia nauplii or rotifer from zoea II to post‐larvae was 66.7% and 68.9%. respectively, without significant difference (P > 0.05). But larvae fed with Artemia nauplii grew significantly (P < 0.05) faster than those fed with rotifer. Larvae fed with Artemia nauplii reached postlarvae in 29–32 d, compared with 32–36 d in the rotifer treatment. Artemia nauplii are also suitable food for the postlarvae and juveniles of L. wurdemanni. The 30 postlarvae fed on Artemia nauplii all survived to reach sexual maturity in 50 to 70 d, growing from about 7 to 28 mm in total length. The effects of four temperature regimes on larval development of L. wurdemanni was also investigated. The duration (mean ± SD d) to the postlarvae at temperatures of 26 C (37.4 ± 5.4) and of 26–30 C daily (40.2 ± 5.8) was significantly (P < 0.05) longer than that at 28.5 C (29.3 ± 4.8) and at 27–29 C daily (28.7 ± 3.5).
Modification of Walleyes Stizostedion vitreum Tolerance to Hydrogen Peroxide Bath Treatment
Authors: Tort M. J. , Kuhl A. J. , Wooster G. A. , Bowser P R.
Published: April 2007

Abstract— Hydrogen peroxide is being evaluated for its potential as a therapeutic compound for a variety of external disease organisms of fish. The value of hydrogen peroxide as a therapeutic compound for use in walleye Stizustedion vitreum culture has been questioned due to the high sensitivity (i.e., high mortality) of walleyes to this compound. We conducted bioassays and histopathological studies to determine if exposure of walleye to hydrogen peroxide bath treatments would result in increased tolerance to subsequent exposure. Test fish exhibited increased tolerance to hydrogen peroxide after initial exposures. This phenomenon of increased tolerance of walleyes to hydrogen peroxide may be of value in the development of management strategies for the successful treatment of fish diseases.
Evaluation of a Kit for Estimating Organic Matter Concentrations in Bottom Soils of Aquaculture Ponds
Authors: Queiroz Julio F , Boyd Claude E.
Published: April 2007

AbstractThe Hach CEL/700 Organic Matter Laboratory provided estimates of organic carbon concentrations in pond soil samples comparable to those obtained by the commonly‐used Walkley‐Black method. Dry ashing at 350–400 C tended to overestimate soil organic matter concentrations, and this procedure requires too much equipment and laboratory expertise for use on most aquaculture farms. The Hach kit can provide practical aquaculturists a simple and reliable method for measuring organic matter in pond soils. Samples from brackishwater ponds should be treated with mercuric sulfate to prevent chloride interference and overestimation of organic matter.
Utilization of Transgenic Fish in Developing Countries: Potential Benefits and Risks
Authors: Dunham Rex A.
Published: April 2007

Recombinant DNA and gene transfer technology now allow the transfer, inheritance and expression of specific DNA or gene sequences into fish. Preliminary results on the performance of the resulting transgenic fish have been quite dramatic in some cases, especially when growth hormone genes are transferred. Utilization of high performance transgenic fish has the potential to greatly increase aquaculture production in developing countries and increase the income of poor farmers. Growth of some transgenic fish has been increased more than 10‐fold in laboratory conditions. Response appears to be greatest in unimproved fish, which in most cases would benefit developing countries the most. The potential increase in production and production efficiency from successful transgenic fish application could relieve pressure on habitat destruction for food production, relieve pressure on overfished natural stocks and discourage introduction of exotic species. Application of transgenic fish in aquaculture has just begun and could expand within a few years. However, prior to commercialization of transgenic fish, public education, environmental risks and food safety issues should be addressed. Genetically improved fish generated by recombinant DNA technology probably do not pose any greater risk to the environment than fish genetically improved through traditional selective breeding, but environmental risk data is lacking to verify this hypothesis. Environmental risk data will be needed in a case‐by‐case basis until more is known concerning the aquaculture potential and ecological risk of transgenic fish. Research institutions need to address the lack of environmental risk data to help ensure that any future application of transgenic fish in developing (and developed) countries be done in an environmentally and socioeconomically sound manner. Socioeconomic study is lacking for detailed cost‐benefit analysis, and policy research is needed for proper application or regulation of transgenic fish in these countries.
The Potential Use of Mangrove Forests as Nitrogen Sinks of Shrimp Aquaculture Pond Effluents: The Role of Denitrification
Authors: Rivera‐Monroy Victor H. , Torres Luis A. , Bahamon Nixon , Newmark Federico , Twilley Robert R.
Published: April 2007

A generalized nitrogen budget was constructed to evaluate the potential role of mangrove sediments as a sink for dissolved inorganic nitrogen (DIN) in shrimp pond effluents. DIN concentrations were measured in pond effluents from three semi‐intensive shrimp ponds along the Caribbean coast of Colombia between 1994–1995. Mean NH4+ concentrations in the discharge water for all farms were significantly higher (67 × 12 μg/L) than in the adjacent estuaries (33 × 8 μg/L). Average NH4+ concentrations in the pond discharge over all growout cycles were similar, representing an approximate doubling in relation to estuarine water concentrations. In contrast, NO2‐+ NO3‐ concentrations were similar in both pond effluent and estuarine waters. Dissolved inorganic nitrogen loading of the ponds was similar. The estimated reduction of DIN in pond effluents by preliminary diversion of outflow to mangrove wetlands rather than directly to estuarine waters would be × 190 mg N/m2 per d. Based on this nitrogen loss and depending upon the enrichment rate, between 0.04 to 0.12 ha of mangrove forest is required to completely remove the DIN load from effluents produced by a 1‐ha pond.
Amino Acid Availability of Four Practical Feed Ingredients Fed to Striped Bass Morone saxatilis
Authors: Small Brian C. , Austic Richard E. , Soares, Jr. Joseph H.
Published: April 2007

Four dietary protein sources were bio‐assayed for amino acid availability, as estimated by true digestibility, when fed to striped bass Morone saxatilis. Diets were formulated to contain either herring fish meal, soybean meal, corn gluten meal or peanut meal as the sole source of dietary protein. A fifth diet, containing no protein, was fed to estimate the level of endogenous amino acids for calculation of true digestibility. The five dietary treatments were randomly assigned to ten tanks of striped bass having an average weight of 150 g per fish. All fish received the assigned diet fed at a rate 1.5% of the biomass per day for a period of 10 d. Fecal samples were collected from anesthetized fish by gentle, manual stripping of the lower digestive tract. Diets and feces were analyzed for dry matter, chromium, nitrogen and amino acid concentrations. There were no statistical differences (P > 0.05) among the protein sources for apparent dry matter digestibility or availability of arginine, threonine, valine and nonessential amino acids with the exception of cysteine. Corn gluten meal had a significantly lower availability coefficient for lysine, and peanut meal had significantly lower availability coefficients for histidine, isoleucine, leucine, and lysine when compared to herring fish meal and soybean meal. Statistically there were no differences between soybean meal and herring fish meal for any nutrient tested. These data suggest that in terms of amino acid availability and overall protein quality, soybean meal could be used to spare herring fish meal in striped bass diets, with corn gluten meal being equally as useful when supplemented with lysine or complemented with other proteins.
Effect of Genistein on the Growth and Reproductive Function of Male and Female Yellow Perch Perca flavescens
Authors: And Kinarm Ko , Malison Jeffrey A. , Reed Jess D.
Published: April 2007

We studied the effect of genistein, a weak estrogenic compound found in soybean products, on the growth and reproductive development of yellow perch Perca flavescens. Four diets were prepared: control, estradiol‐17β (E2) at 10 μg/g diet (E10), and genistein at 7.5 and 0.75 mg/g diet (G7.5 and G0.75). Fish (initial weight = 13–15.5 g and initial total length = 105–111 mm) were fed to excess for 63 d. The E10 diet promoted weight gain in yellow perch of both sexes, whereas the G7.5 diet decreased weight gain in females. The growth of the G0.75 group was not different from either the E10 group or the control group. Among females, fish fed the E10 diet had the lowest plasma concentration of E2 36 h after the last feeding of the study. The plasma concentration of E2 did not differ among the males from the four treatments. The E10‐treated fish of both sexes had increased plasma concentration of alkali‐labile phosphoprotein phosphorous (ALPP) in both sexes, indicating that vitellogenesis had been induced. Neither genistein diet increased plasma (ALPP) concentration. Male but not female yellow perch fed the E10 diet had significantly lower gonadosomatic indices compared to control and genistein groups. These results suggest that genistein may have a positive effect on growth in yellow perch, but no apparent estrogenic effects on reproductive function.
Quantitative Dietary Threonine Requirement of Juvenile Striped Bass Morone saxatilis
Authors: Small Brian C. , Soares Joseph H.
Published: April 2007

A 10‐wk feeding trial was conducted to quantify the dietary threonine requirement of juvenile striped bass Morone saxatilis. The basal diet was analyzed to contain 42% crude protein with a calculated digestible energy (DE) level of 3,200 kcal/kg. L‐threonine was added to the basal diet to yield five dietary treatments of 0.61, 0.81, 1.00, 1.18, and 1.40% available threonine on a dry‐matter basis. Weight gain, specific growth rate (SGR), feed conversion ratio (FCR) and apparent nitrogen utilization (ANU) were significantly (P < 0.05) affected by dietary threonine concentrations. Least‐squares regression analysis of weight gain, SGR, FCR, and ANU indicated dietary threonine requirements (±SE) of 1.00 ± 0.19, 0.91 ± 0.11, 1.06 ± 0.09 and 1.13 ± 0.22% of dry diet, respectively. From these results, the average recommended dietary threonine requirement of juvenile striped bass is 1.03% of dry diet, 2.45% of dietary protein or 3.22 mg/kcal DE.
Evaluation of the Ultraviolet Spectrophotometric Method for the Measurement of Total Nitrogen in Water
Authors: Gross Amit , Boyd Claude E. , Seo Jinwon
Published: April 2007

Abstract.— A simple, accurate, and environmentally sound procedure based on spectroscopy in the UV range was modified to measure total nitrogen concentrations in both freshwater and brackishwater. Water samples from freshwater fish ponds were analyzed for total nitrogen with the persulfate digestion method followed by analysis of nitrate with the UV method for comparison with the NAS reagent method. Brackishwater samples with salinities of 8 to 10 ppt from shrimp ponds were digested by the persulfate method and analyzed with the UV method. Percentage recovery of nitrogen and also precision were evaluated for the UV method. Nitrate concentrations in the freshwater persulfate digests determined by the UV method were similar to those obtained by the NAS reagent method (P < 0.05). The slope of the regression line did not differ from 1.0 (P < 0.05). Precision of both methods was acceptable over the range of nitrogen concentration used, but precision of the UV method tended to be better than that of the NAS method. Spike recovery averaged 97.4% in the NAS reagent method and 107.2% in the UV method. Interference from organic matter was minor in the UV method, because virtually all of the organic matter was oxidized during the digestion. Precision with brackishwater samples was slightly better than the freshwater samples and percentage spike recovery averaged 102.8%. Because spectrophotometers in most laboratories have the capability of reading in the UV range, the UV method is an attractive alternative for total nitrogen analysis.
Salinity Effects on Early Life Stages of Southern Flounder Paralichthys lethostigma
Authors: Smith Theodore I. J. , Denson Michael R. , Heyward Louis D. , Jenkins Wallace E. , Carter Lisa M.
Published: April 2007

Abstract.— In South Carolina, studies have been conducted to develop rearing techniques for southern flounder Paralichthys lethostigma a candidate for aquaculture development and stock enhancement programs. To help define environmental tolerances, a variety of salinity studies were conducted with the early life stages of this species. Eggs were buoyant at 32 ppt and sank at 29 ppt with salinities of 30–31 ppt providing varying levels of suspension in the water column. Eggs incubated at 0 and 5 ppt all died, whereas 82.5% hatched at 10 ppt but larvae died shortly thereafter. At 63 h post‐fertilization, there were no differences in hatch level for eggs incubated at salinities of 15 to 35 ppt (mean hatch level 98.5%). In a 72‐h study, fish 3 wk post‐metamorphosis (13.7 mm TL, 50‐d‐old) were acclimated to seven salinities ranging from 0–30 ppt. Fish held at 0 ppt salinity exhibited a statistically (P < 0.05) lower survival (20.0%) than those exposed to 5–30 ppt salinity concentrations. No differences were detected in survival (mean 99.1%) among fish held in the higher salinities. A second study examined the tolerance of older juveniles to lower salinities. Juvenile flounder (95.2 mm TL, 220‐d‐old) were acclimated to 0, 1,5 and 10 ppt salinities and reared for 2 wk. Results showed that fish could tolerate salinities of 0–10 ppt (100% survival). These data indicate that salinity tolerance of southern flounder increases with age. In addition to the short duration studies, a replicated 11‐mo duration tank grow‐out study was conducted at mean salinity 5.4 ppt and mean temperahue 22.6 C with an all male population. Flounder grew from a mean length of 100 mm to 213 mm TL and weight from 8.9 to 104.3 g. Growth of the cultured fish approximated that observed among male flounders in the wild.
Induction of Triploidy and Tetraploidy in Nile Tilapia, Oreochromis niloticus (L.)
Authors: El Gamal Abdel‐Rahman A. , Davis Kenneth B. , Jenkins Jill A. , Torrans E. Les
Published: April 2007

Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus, was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy.
The Effects of Tidal and Bottom Placement on the Growth, Survival and Fouling of the Eastern Oyster Crassostrea virginica
Authors: Moroney Deborah A. , Walker Randal L.
Published: April 2007

Oysters Crassostrea virginica in Georgia are naturally small and grow in clusters; however, it is more profitable to harvest large, single oysters. This study attempts to identify favorable tidal and bottom placements for the grow‐out of large, single oysters in Georgia. Three bags, each containing 50 single oysters, were placed in four different tidal positions (subtidal on‐bottom, subtidal off‐bottom, intertidal on‐bottom and intertidal off‐bottom) at five sites in House Creek, Georgia. Measurements of oyster growth, survival and degree of oyster spat fouling were taken seasonally (every 3 mo). Oysters from on‐bottom treatments exhibited significantly lower growth (P = 0.0364 intertidal only), survival (P = 0.0044) and degree of fouling (P= 0.0154) than oysters from the intertidal off‐bottom treatment. However, the oysters placed intertidally off‐bottom were heavily fouled during the recruitment period. It may be necessary to sacrifice some growth and survival by culturing oysters intertidally on‐bottom during the recruitment period in order to reduce the degree of fouling. During the non‐recruitment period, placing oyster culture bags intertidally off‐bottom maximizes growth and survival.
The Effects of Exogenous Bovine Growth Hormone and Placental Lactogen on Juvenile Striped Bass Morone saxatilis Feed and Growth Efficiency
Authors: Hunt Amy S. , Soares Joseph H. , Byatt John C. , Dahl Geoffrey E.
Published: April 2007

Striped bass Morone saxatilis under normal pond‐reared conditions usually requires 14–18 mo to grow out to market weight. This includes a winter of comparatively slower growth which could possibly be overcome through hormonally induced acceleration of growth. Thus, the objective of this experiment was to test the hypothesis that bovine growth hormone and bovine placental lactogen increase growth in striped bass in a dose dependent manner. A secondary objective was to determine the effect of these hormones on body composition. Variables tested were weight gain, length gain, condition factor, feed conversion, and body composition. Fish injected biweekly with 10 μg/g body weight, bovine placental lactogen (P < 0.09) or bovine growth hormone (P < 0.11) increased body weight. Fish injected with 1 or 10 μg/g body weight bovine placental lactogen (P < 0.10) or bovine growth hormone (P < 0.10) increased body length during the 12‐wk study period. Proximate analysis indicated that bovine growth hormone increased protein content (10 μg/g; P < 0.10) and decreased fat content (1 and 10 μg/g; P < 0.10). No significant differences occurred in feed conversions. We conclude that bovine growth hormone and bovine placental lactogen are effective in increasing body growth in striped bass.
Comparison of Growth, Processing Yield, and Body Composition of USDA103 and Mississippi “Normal” Strains of Channel Catfish Fed Diets Containing Three Concentrations of Protein
Authors: Li Menghe H. , Manning Bruce B. , Robinson Edwin H. , Bosworth Brian G. , Wolters William R.
Published: April 2007

Abstract.— This study evaluated the effects of dietary protein concentration (26, 28, and 32%) on growth. feed efficiency, processing yield, and body composition of USDA103 and Mississippi “normal” (MN) strains of channel catfish raised in ponds. Fin‐gerling channel catfish (average weight = 32.5 and 47.3 g/fish for USDA103 and MN strains, respectively) were stocked into 24 0.04‐ha ponds (12 ponds/ strain) at a density of 18,530 fish/ha. Fish were fed once daily to apparent satiation from May to October 1999. There were no interactions between fish strain and dietary protein concentration for any parameters measured. Regardless of dietary protein concentrations, the USDA103 strain consumed more feed and gained more weight than the MN strain. There were no differences in feed conversion ratio (FCR) or survival between the two strains. Feed consumption, weight gain, FCR, and survival were not affected by dietary protein concentration. The USDA103 strain exhibited a lower level of visceral fat, a higher carcass yield, a lower level of fillet moisture, and a higher level of fillet fat than the MN strain. Regardless of fish strains, fish fed the 32% protein diet had a lower level of visceral fat and a higher fillet yield than fish fed the 26% protein diet. Fish fed the 32% protein diet were also higher in carcass yield as compared to those fed the 28% protein diet. Fillet moisture, protein, and fat concentrations were not affected by dietary protein concentration. Results from this study indicate that the USDA103 strain of channel catfish appears to possess superior traits in growth characteristics compared with the MN strain that is currently cultured commercially. Both strains appear to have the same dietary protein requirement.
Efficacy of Benzocaine as an Anesthetic in Juvenile Tambaqui Colossoma macropomum
Authors: Gomes Levy C. , Chippari‐Gomes Adriana R. , Lopes Nívia P. , Roubach Rodrigo , Araujo‐Lima Carlos A.R.M.
Published: April 2007

Abstract.— The present study investigated the use of benzocaine as an anesthetic for juvenile Colossoma macropomum (tambaqui). In the first experiment, fish were exposed to various doses of benzocaine for 10 min at 24 C. The second experiment examined the effects of duration of exposure to 100 mg/L of benzocaine. In the third experiment, fish were exposed to 100 mg/L at temperatures of 24, 27, and 30 C. Benzocaine concentrations of 100–150 mg/L were considered ideal for quickly inducing total immobilization and fast recovery. Fish exposed to 350 mg/L benzocaine exhibited 30% mortality. No changes in hemat‐ocrit were recorded in fish exposed to different concentrations of benzocaine. Plasma glucose increased significantly when fish were exposed to benzocaine concentrations greater than 200 mg/L. Recovery time after a 30‐min exposure to 100 mg/L benzocaine was significantly greater than after an exposure for 10 and 20 min. No mortality was observed 96 h after exposure to 100 mg/L benzocaine for 10, 20, and 30 min. Dosages in the 100–150 mg/L range were effective for periods of up to 20 min of anesthesia. There was no effect of temperature on the time required for fish to lose equilibrium. However, recovery was significantly faster for fish anesthetized at 30 C. Benzocaine is an effective anesthetic agent for tambaqui juveniles, providing rapid immobilization and rapid recovery. Benzocaine is also less expensive than other available anesthetic compounds.
Evaluation of Corn Gluten Feed as a Dietary Ingredient for Pond‐Raised Channel Catfish Ictalurus punctatus
Authors: Robinson Edwin H. , Li Menghe H. , Manning Bruce B.
Published: April 2007

Abstract.— This study was conducted to evaluate corn gluten feed as an alternative feedstuff in the diet of pond‐raised channel catfish Ictalurus punctatus. Three 32%‐protein diets containing 0%, 25%, or 50% corn gluten feed were tested. Channel catfish fingerlings (average weight: 57 g/fish) were stocked into 15 0.04‐ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed to satiation once daily for a 147‐d growing period. No differences were observed in feed consumption, weight gain, feed conversion ratio, survival, or fillet protein concentration among fish fed the test diets. Fish fed diets containing 25% and 50% corn gluten feed exhibited a lower level of visceral fat and a higher carcass yield than fish fed the control diet without corn gluten feed. The diet containing 50% corn gluten feed resulted in a lower level of fillet fat and a higher level of moisture than the control diet. There were no visible differences in the coloration of skin or fillet of channel catfish fed diets with and without corn gluten feed. Results from this study indicated that channel catfish can efficiently utilize corn gluten feed at levels up to 50%n without adverse effect on feed palatability, weight gain, or feed efficiency. Corn gluten feed may be beneficial in reducing fattiness of channel catfish and improving carcass yield by reducing the digestible energy to protein ratio of the diet.
Phytoplankton Community Structure, Biomass, and Off‐flavor: Pond Size Relationships in Louisiana Catfish Ponds
Authors: Zimba Paul V. , Grimm Casey C. , Dionigi Christopher P. , Weirich Charles R.
Published: April 2007

Abstract.— Many aquaculture studies are conducted in relatively small research ponds and the results are then extrapolated to larger commercial ponds. Implicit in this research is the assumption that there is no relationship between pond size and phytoplankton composition. Study objectives were to assess phytoplankton composition and biomass by several methods in 17 channel catfish Ictalurus punctatus ponds at the Aqua‐culture Research Station, Louisiana Agricultural Experiment Station in Baton Rouge, Louisiana, USA. Pond size ranged from 0.04–0.60 ha. Sampling occurred weekly from 10 September – 1 October 1997. Water temperatures coincided with a transition from summer to fall‐winter conditions. Biomass was assessed by cell counts and quantification of photopigments. Concentrations of dissolved off‐flavor compounds (2‐methylisoborneol and geosmin) were assessed by gas chromatography/mass spectroscopy of water column samples. Cell count data showed differences in dominant species, biovolume, and diagnostic pigment signatures among ponds. The smaller ponds had more diverse phytoplankton composition compared to the larger ponds, whereas chlorophyll levels were nearly an order of magnitude lower in the smaller ponds. Ultraplanktonic (2–20 μm) unicellular cyanobacteria dominated the numerical counts on most sampling dates; however, biovolume transformations of cell count data reduced the dominance of this component relative to cryptophytes, diatoms, and filamentous cyanobacteria. Pigment and microscopic analyses were well correlated. Unialgal isolates of dominant taxa from these samples indicated the presence of at least five genera of off‐flavor producers in these ponds; these taxa included Anabaena, Aphanizomenon, Pseudanabaena, as well as two species of Oscillatoria. Care in extrapolating results from smaller‐sized research ponds to larger commercial ponds is warranted, as is the potential for taxa other than Oscillatoria and Anabaena in forming off‐flavor compounds.
Evaluation of Meat and Bone Meal in Practical Diets Fed to Juvenile Hybrid Striped Bass Morone chrysops×M. saxatilis
Authors: Bharadwaj Anant S. , Brignon William R. , Gould Nathan L. , Brown Paul B. , Wu Y. Victor
Published: April 2007

Juvenile hybrid striped bass (Morone chrysops×M. saxatilis) were fed one of eight diets to evaluate meat and bone meal as a source of crude protein and essential amino acids. Diets contained either 0, 15, 20, 25, 30, 35, 40 or 45% meat and bone meal substituted for an isonitrogenous amount of soybean meal and fish meal. All diets were fed for 7 wk, followed by a 2‐wk digestibility trial. Mean consumption, weight gain, and feed conversion ratio were not significantly affected by addition of meat and bone meal into diets. Intraperitoneal and liver lipid concentrations were not significantly affected by meat and bone meal. Fillet proximate composition was not significantly different among treatments. Apparent crude protein, phosphorus, and amino acid availabilities were significantly lower in fish fed 45% meat and bone meal compared to fish fed 30% and lower concentrations and generally lower in fish fed greater than 30% meat and bone meal. Based on these data, it appears meat and bone meal can be used as the primary source of crude protein and essential amino acids in practical growout diets for hybrid striped bass, comprising as much as 45% of the diet. Nutrient availability values were lower in fish fed greater than 30% meat and bone meal and may restrict usage in some applications.
Enhancement of Stress Resistance of the Guppy Poecilia reticulata through Feeding with Vitamin C Supplement
Authors: Lim Lian Chuan , Dhert Philippe , Chew Wei Yen , Dermaux Veerle , Nelis Hans , Sorgeloos Patrick
Published: April 2007

This study investigated the use of vitamin C supplement in formulated diets and live Artemia juveniles to enhance the stress resistance of the guppy Poecilia reticulata. To evaluate the stress resistance, fish were subjected to osmotic shock in pre‐aerated water containing 35 ppt sodium chloride. Ascorbyl acid‐polyphosphate and ascorbyl palmitate were used as vitamin C sources for formulated diets and live Artemia juveniles, respectively. Results showed that guppies fed moist formulated diets supplemented with ascorbic acid at 1,000 mg/kg or 2,000 mg/kg diet displayed significantly higher levels of stress resistance than fish fed control formulated diet for 13 d. The stress resistance of fish fed a lower dose (200 mg/kg diet), however, did not differ significantly from that of the control. On the other hand, the stress resistance of guppies fed Artemia juveniles bio‐encapsulated with 10% or 20% ascorbyl palmitate did not show significant difference from that of fish fed control Artemia after 20 d. The stress resistance of these three groups of Artemia‐fed fish, however, was significantly higher than that of fish fed the control formulated diet. Biochemical analyses showed that raising the ascorbic acid level in feeds resulted in a concomitant increase in the incorporated ascorbic acid level in the whole‐body tissue of the guppy. The increased stress resistance of the guppy fed a vitamin C supplemented diet has also been demonstrated in four commercial farms. The potential application of the improved stress resistance in the ornamental fish industry was discussed.
The Cryopreservation of Striped Bass Morone saxatilis Semen
Authors: Jenkins‐Keeran Karen , Woods L. Curry
Published: April 2007

Abstract.— Two experiments were designed to improve upon existing methods for cryopreserving striped bass Morone saxatilis, semen. In the first experiment, two extenders, two cryoprotectant concentrations, and two freezing rates were evaluated on the basis of post‐thaw semen motility after 1, 7, and 30 d of storage at −196 C. Semen samples cryopreserved at a freezing rate of −40 C/m resulted in a significantly higher percentage of motile sperm (P < 0.001) and longer duration of spermatozoa motility (P < 0.001) than samples cryopreserved at a freezing rate of ‐30 Chin. Also, the cryoprotectant dimethyl‐sulfoxide yielded a significantly higher percentage of motile sperm (P < 0.001) and longer duration of spermatozoa motility (P < 0.001) when a 5% concentration was used instead of 7.5%. In the second experiment, the two extenders from Experiment I were re‐evaluated and a new extender, which was a modified version of Extender 1, was tested. The samples were cryopreserved at ‐40 C/min with 5% DMSO and thawed in a 25 C water bath. Spermatozoa motility and fertilization ability were evaluated, and semen cryopreserved in Extender 2 yielded the longest duration of spermatozoa motility (P < 0.001). the highest percentage of motile sperm (P < 0.001). and the highest percentage of fertilized eggs (P < 0.002) in comparison to Extenders I and 3.
The Effect of Dietary Carotenoids on Gonad Production and Carotenoid Profiles in the Sea Urchin Lytechinus variegatus
Authors: Plank Larry R. , Lawrence John M. , Lawrence Addison L. , Olvera Ricardo Montoya
Published: April 2007

Although dietary carotenoids are generally considered important in sea urchin aquaculture only for their effect on gonad color, they also have important biological roles. The effects of dietary carotenoids on gonad production and organ carotenoid profiles of Lytechinus variegatus were examined. Individuals were collected in January 1999 and fed a replete diet with a level of 0.60 mg carotenoids/kg for 4 wk, followed by one of four prepared diets for 8 wk: one without supplemental carotenoids, one with β‐carotene (16.92 mg carotenoids/kg feed), and two carotenoid mixtures, one high in zeaxanthin (5.28 mg carotenoids/kg feed) and another high in capsanthin (9.63 mg carotenoids/kg feed). The carotenoid profiles of the body compartments differed. The primary carotenoid in gonads of males and females was echi‐nenone. The carotenoid profile of the test was similar to that of the gonad. The carotenoid profile of the gut varied with diet, but was not identical to composition of the diet. The gut profiles included echinenone but at lower concentrations than in the gonad and test. The carotenoid profile in the gut probably results from the presence of the carotenoids absorbed and those metabolized. The results suggest that several pathways exist to metabolize dietary carotenoids and that some of them are in the gut. The concentration of carotenoids in the gut (g wet weight) was higher than that of the gonad, which was higher than that of the test. The gonads increased significantly in size regardless of diet, indicating carotenoids are not required for gonad production under the conditions of this experiment. Although the concentration of carotenoids in the gonad decreased over time, the absolute amount of carotenoids increased with the increase in gonad size. Either gonad growth was more rapid than carotenoid deposition or differential deposition in nutritive cells and gametogenic cells occurred, or the amount of carotenoids used in the diets was too low to have an effect.
Phototrophic Bacteria as Feed Supplement for Rearing Penaeus monodon Larvae
Authors: Azad Sujjat Al , Chong Ving C. , Vikineswary S.
Published: April 2007

Larvae of the giant tiger prawn Penaeus monodon were reared from the naupliar to pos‐tlarval stage, based on a diet of waste‐grown phototrophic bacterium Rhodovulum sulfido‐philum, the marine diatom Skeletonema costatum, and brine shrimp Artemia The experimental design consisted of feeding the protozoea with diatoms and varying proportions of bacterial biomass as diet D0 (0%), D1 (1%), D2 (2%), D3 (3%), and D5 (5%), while mysis and postlarvae were fed the above diet supplemented with Artemia nauplii. Controls were not fed with bacteria biomass (diet D0). The addition of R. sulfidophilum biomass in the diet had significant effects on the growth and survival of P. monodon larvae. In the first experiment, the larvae fed with diet D1 (Skeletonema+ 1%R. sulfidophilum) reached the first postlarval stage (PL1) on the ninth day of feeding and had a mean total length (TL) of 6.13 ± 0.05 mm, which was significantly higher (P < 0.001) than TL of larvae fed with the other three diets. In another experiment, prawn larvae fed with diet D2 had the highest overall survival of 46% and a significantly larger mean TL of 6.88 ± 0.18 mm at PL1 compared to larvae fed with diet D0 and D3 (P > 0.05). However, in both experiments prawn larvae fed with the various diets showed significant differences in their length‐at‐stage (P > 0.05), and the lowest growth and survival were obtained from diets comprising 3% and 5% bacterial biomass, which also gave the highest levels of ammonia‐nitrogen in the culture water. Addition of more than 2% R. sulfidophilum biomass apparently deteriorates the quality of the culture water.
Optimization of Feeding Rate for Hatchery‐Produced Juvenile Gilthead Sea Bream Sparus aurata
Authors: Mihelakakis Apostolos , Tsolkas Christos , Yoshimatsu Takao
Published: April 2007

Abstract.— A 61‐d growth trial (five 11‐d feeding periods) was conducted to determine the effects of feeding rate on growth, feed utilization, morphology, and body composition of the gilthead sea bream Sparus aurata. Gilthead sea bream juveniles with an average initial body weight of 3 g were fed a commercial diet (51% crude protein, 11% crude fat) at rates of 0.5, 1.0, 1.5, 2.0, 2.5, or 3.0% of their body weight (BW) per day in two equal meals. Water temperature was approximately 21.4 C throughout the experiment. Each ration was administered to triplicate groups of 60 fish, with ration readjusted every 11 d. Growth rate was measured as specific growth rate (SGR). Survival rate and coefficient of variation did not differ significantly among the groups fed different rates. Body weight, condition factor, and hepatosomatic and viscerosomat‐ic indices displayed significant increases with increasing feeding rate from 0.5 to 3.0% BW/d. Fish fed 0.5% BW/d had significantly higher moisture and ash and lower protein contents than those fed at higher rates. Moisture and protein contents were not significantly different for fish fed at the highest feeding rates (2.0, 2.5, and 3.0% BW/d). Lipid contents increased significantly with increasing feeding rate from 0.5 to 3.0% BW/d. The SGR showed a curvilinear significant increase when the feeding rate was increased from 0.5 to 3.0% BW/d. Feed efficiency (FE) increased significantly to a maximum value with increasing feeding rate from 0.5 to 2.0% BW/d and decreased significantly with increasing feeding rate from 2.5 to 3.0% BW/d. Based on the data obtained, feeding rates of 2.3% and 0.6% BW/d are recommended as optimum and maintenance rations, respectively.