bluuebunny/crossref_metadata_2025 huggingface dataset:
Supplemental Feeding of Tilapia in Fertilized Ponds
Authors: Diana James S. , Lin C. Kwei , Jaiyen Kitjar
Published: April 2007

The addition of feed to fertilized fish ponds was evaluated by adding feed alone, feed plus fertilizer, or fertilizer alone to nine ponds stocked with Nile tilapia Oreochromis niloticus. Two experiments were conducted. The first had 500 fish per 250 m2 pond in 3 treatments: ad‐libitum feeding; fertilizer only; or fertilizer and ad‐libitum feeding. The second experiment had 5 treatments with 750 fish per pond ad‐libitum feed only; fertilizer only; or 0.25, 0.50, and 0.75 satiation ration plus fertilizer. Ponds in Thailand were maintained for 155–162 d, during which chemical and physical properties were monitored. In experiment 1 tilapia growth was highest in feed only ponds, and lowest in fertilizer only ponds. Net yield did not differ significantly among treatments, due to variation in survival. In experiment 2, tilapia growth was lowest in fertilizer only ponds, intermediate in 0.25 ration ponds, and highest in 0.50, 0.75, and ad‐libitum ponds. The latter treatments were not significantly different. Multiple regressions for each experiment indicated only 47–87% of the variance in growth was explained by feed and fertilizer input, while 52–89% of the variance in yield was explained by those factors. For both experiments combined, 90.3% of the variance in growth was explained by feed input, fertilizer input, alkalinity, and total inorganic nitrogen concentration. For yield, R2 was 0.888 and the regression included feed input, pH, and number of low dissolved oxygen events. Experiment 1 appeared to approach carrying capacity near the end, while no reduction in growth occurred in experiment 2 at higher fish density and biomass. Reductions in growth in experiment 1 were not correlated with declining water quality late in the grow out. Combinations of feed and fertilizer were most efficient in growing tilapia to large size (500 g) compared to complete feeding or fertilizing alone.
Pressure Induced Triploidy in Hybrid Lepomis
Authors: Wills Paul S. , Paret John M. , Sheehan Robert J.
Published: April 2007

Worldwide expansion of aquaculture will require identification of species more adapted to localized conditions and less likely to affect genetic diversity of natural populations in the event of escape. Hybrids of Lepomis sunfish have the potential as an alternative for aquaculture in regions of North America where the growing season is unsuitable for production of traditional coldwater and warm‐water species. Triploidy was induced in hybrids of green sunfish Lepomis cyanellus males and bluegill L. macrochirus females using hydrostatic pressure shocks. A total of 27 combinations of pressure (41,369, 48,264, and 55,158 kPa), duration (2, 3, 4 min), and post‐fertilization time of shock initiation (2, 3, 4 min) were tested to identify those which were most efficient for inducing triploidy. Several of the shock regimes produced 100% triploid hybrid sunfish with at least 90% survival relative to unshocked controls. The two shock treatments deemed best overall were: 1) 48,264 kPa for 4 min begun 2 min after fertilization; and 2) 41,369 kPa for 2 min begun 3 min after fertilization.
Growth Response of Penaeus setiferus to Four Commercial Feeds Under Controlled Laboratory Conditions
Authors: Davis D. Allen , Arnold C. R.
Published: April 2007

Shrimp farmers have access to and have evaluated a diverse number of shrimp species; however, due to culture and market considerations three penaeid species (Penaeus monodon, P. orientalis and P. vunnamei) account for 80% of the world production (Weidner and Rosenbeny 1992). Although culture techniques for these species have been extensively studied and are relatively well established, they are not native to U.S. coastal waters and hence possess problems associated with the use of exotic species. Three native species P. aztecus. brown shrimp; P. duorarum, pink shrimp; and P. setiferus, white shrimp, support commercial fisheries along the Gulf states (Gulf of Mexico Fishery Management Council 1981). The commercial culture of these species would avoid the inherent problems associated with the culture of exotic species and allow shrimp farmers in the Caribbean basin to more effectively expand operations.
Effects of Population Density and Feeding Rate on Growth and Feed Consumption of Red Swamp Crawfish Procambarns clarkii
Authors: McClain W. Ray
Published: April 2007

Wire‐mesh enclosures were used in production ponds to conduct growth trials in which population density and feeding rate were evaluated in a 2 × 2 factorial arrangement for their effects on crawfish growth. Juvenile Procambarus clarkii of uniform size (0.5 g) were stocked at 2 or 20 animals/m2 in experiment 1 and weighed biweekly for 12 wk. Rice forage served as the detrital base, and supplemental feed (25% crude protein) was provided at either a low (26–52 kg/ha per week) or high (104–418 kg/ha per week) rate. In experiment 2, mixed sizes of crawfish were stocked at 10/m2 or 20/m2 and fed the formulated feed at either 52 or 312 kg/ha per week. Feed consumption was estimated for each treatment combination. Only population density significantly affected crawfish growth. Mean weight gain and final weights were inversely proportional to density but only when total crawfish biomass exceeded 1,235 kg/ha. Growth was not significantly influenced by feeding rate, but the high feeding rate resulted in a significantly greater ratio of hepatopancreas weight to body weight and tended to decrease hepatopancreas moisture levels, indicating improved condition. Population density, feeding rate, and their interaction had significant effects on estimated feed consumption. From the simple linear regression of mean feed consumption on crawfish standing crop, it was estimated that crawfish consume about 0.1 kg of dry feed per ha per week per kg of crawfish biomass on a 5 d per week feeding schedule at mean water temperatures, ranging from 14 to 30 C.
Growth of Crawfish Procambarus clarkii as a Function of Density and Food Resources
Authors: McClain W. Ray
Published: April 2007

This study utilized enclosures (cylindrical, 5‐mm wire mesh, O.5 m2 bottom surface area) placed over rice‐forage substrates in experimental crawfish ponds to contain crawfish under typical pond culture conditions. Juvenile Procambarus clarkii were stocked at six densities (2, 4, 6, 10, 14, and 18 crawfish/m2) for 12‐wk growth trials in October and again in February. Crawfish relied solely on the detrital food system for their nutritional needs. Supplemental feed was supplied to crawfish in additional enclosures at two of the test densities (2 and 10 crawfish/m2). The commercially formulated feed (25% crude protein) was fed (2.02 g dry feed/m2) 3 d/wk (Monday, Wednesday, Friday). All treatments were replicated with six enclosures. Crawfish growth was inversely correlated to culture density. Mean final weights for crawfish feeding from the detrital‐system only were 15.3, 13.8, 11.2, 7.9, 7.2, and 5.8 g for crawfish densities of 2, 4, 6, 8, 10, 14, and 18/m2, respectively. Mean final weights for crawfish receiving supplemental feed were 20.7 and 12.4 g for densities of 2 and 10 crawfish/m2. When compared with density as a factor influencing growth, feed influenced growth less than density abatement. Supplemental feeding improved crawfish growth in detrital systems an average of 46%, while decreasing initial density improved growth an average of 80.5%.
Observations on Monosex Culture of Redclaw Crayfish Cherax quadricarinatus von Martens (Decapoda: Parastacidae) in Earthen Ponds
Authors: Curtis Millin C. , Jones Clive M.
Published: April 2007

Manual sexing of redclaw crayfish Cherar quadricurinatus was undertaken to evaluate the feasibility of monosex culture and to establish growth and yield characteristics of single sex populations. Although the all‐male population exhibited greater mean weight after 10 mo of growout, all‐female and mixed sex populations achieved greater total yields due to significant juvenile recruitment. Commercial cultivation of all‐male populations would be advantageous as in‐pond reproduction is greatly abated, growth is superior and marketable yield is higher. Apparent sexual lability of juveniles combined with the laborious nature of manual sexing may render manual sexing unsuitable for commercial applications.
Mathematical Model of a Foam Fractionator Used in Aquaculture
Authors: Timmons M. B. , Chen S. , Weeks N. C.
Published: April 2007

Water recirculating systems are becoming more prevalent as wild fish supplies and fresh water sources become increasingly scarce. As water recirculating rates increase, the accumulation of fine and dissolved solids can degrade water quality and fish productivity. Foam fractionators have been used with some success to remove these solids, although an understanding of how to best operate such units is currently lacking. The foam enrichment process occurs as bubbles travel from the bottom of a fractionator column to the top of the water column. Factors affecting bubble enrichment include several operating or design parameters under operator control or influence, e.g, water pH, gas bubble size, airflow rates, and fractionator geometry. Predictive relationships were developed to describe these effects and are considered generally applicable to predict the foam enrichment process. Predicting the actual operation of a specific foam fractionator requires additional mathematical expressions to model the foam collection process and removal from the top of the water column. Here, the geometric characteristics and type of foam removal device or geometry of placement become important. Performance data in the literature was used in coajunction with a mathematical model that predicted foam enrichment to model the foam collection process for a typical foam fractionator design. This overall model can be used for foam fractionators that employ glass bonded air diffusers with an inverted funnel at the top of the fractionator column to concentrate and remove the foam being produced. An example problem is given to demonstrate the utility of the mathematical models. Since foam fractionators are typified by erratic performance, the mathematid models presented must be used with some caution and only viewed as providing estimates of average fractionator performance.
Induced Spawning of Wild American Shad Alosa sapidissima Using Sustained Administration of Gonadotropin‐Releasing Hormone Analog (GnRHa)
Authors: Mylonas Costadinos C. , Zohar Yonathan , Richardson Brian M. , Minkkinen Steven P.
Published: April 2007

American shad Alosa supidissima broodstock were collected from the Susquehanna River during their spawning migration. Mean volume of expressible milt (± standard deviation) was 2.5 (±1.7) mL/kg body weight; mean spermatozoid count was 66.2 ± 109 (±163 ± 109) spermntozoa/mL; and duration of 50% motility was 36.5 (±10.3) see. Ovarian biopsies indicated the presence of oocytes of various sizes (200–2,000 μm in diameter) and stages of development. Fish were implanted with a delivery system loaded with gonadotropin‐releasing hormone analog (GnRHa) and started spawning 2 d after treatment. Fertile eggs were collected daily for the next 9 d, for a total of 50,100 eggs/kg body weight with a mean fertilization success of 62%. Upon cessation of spawning, the ovaries of all females still contained large numbers of oocytes at various stages of development, as at the beginning of the experiment, but with a greater number of atretic oacytes. Our observations show that American shad have an asynchronous ovarian development, and treatment with a GnRHa delivery system is effective in inducing several successive spawns of fertile eggs.
Effect of Time of Feeding on Growth of Channel Catfish1
Authors: Robinson Edwin H. , Jackson L. Scott , Li Meng H. , Kingsbury Susan K. , Tucker Craig S.
Published: April 2007

Channel catfish fingerlings were stocked into 16 0.04‐ha ponds at a rate of 24,700 fish/ha on 5 May 1992. Four replicate ponds were used for each of the following treatments: 1) fed once daily at 0830h; 2) fed once daily at 1600h; 3) fed once daily at 2000h; and 4) fed on demand using demand feeders. Fish on the first three treatments were fed to satiation. All fish were harvested 145d after stocking. Results from this study showed that when channel catfish raised in ponds were fed once daily to satiation, time of feeding had no significant impact on water quality, feed consumption, feed conversion, weight gain, or body proximate composition. Fish fed on demand consumed more feed than fish fed once daily to satiation, but difference in weight gain was not significant. These data indicated that feeding time may not be critical for channel catfish production as long as fish are fed when dissolved oxygen is sufficient. Although feeding at night was not detrimental in this study, night feeding is not recommended on large ponds unless sufficient aeration is available to quickly provide oxygen in an emergency—and even then it would be problematic.
Optimization of Dissolved Solids for the Intensive Culture of Juvenile Red Drum Sciaenops ocellatus
Authors: Stahl Christopher J. , Barnes Steven S. , Neill William H.
Published: April 2007

Survival and growth of 0.3–0.9 g red drum Sciaenops ocellatus were measured for fish reared in water‐recirculating culture systems containing one of the following media: 6g/L diluted seawater; 1g/L diluted seawater; 1g/L diluted seawater with either 1 or 5g/L of additional salt. Salt was added as sodium chloride, calcium chloride, or magnesium sulfate. Mean survival over the 42‐d study period was 56.3%. The 5g/L sodium chloride treatment had the highest survival rate (80.0%) and the calcium chloride treatment had the lowest (26.7%). The biomass‐change rate for fish in the 5g/L calcium chloride treatment was significantly lower (P < 0.05) than for fish in the 5g/L sodium chloride, 1g/L sodium chloride, or 5g/L magnesium sulfate treatments. The latter three treatments gave biomass‐change rates that did not differ (P > 0.05) from those obtained in the 1 or 6g/L diluted seawater.
Masculinization of Channel Catfish Ictalurus punctatus by Oral Administration of Trenbolone Acetate
Authors: Galvez John I. , Mazik Patricia M. , Phelps Ronald P. , Mulvaney Donald R.
Published: April 2007

All‐male populations of channel catfish, Ictalurus punelatus, were produced by feeding a diet containing trenbolone acetate to swim‐up fry for 60 d. This hormone was effective in producing 100% males at doses of 50 to 150 mg/kg of diet. Fish that received 0 or 1 mg/kg of diet did not differ from the expected 1:1 sex ratio. Survival of control fish and fish fed diets containing trenbolone acetate were similar (P > 0.05) at the end of the treatment period and after a 60‐d grow‐out period. Our results represent the first report of successful masculinization of channel catfish with a synthetic anabolic androgenic steroid.
Comparative Growth of Diploid and Triploid Asian Catfish Clarias macrocephalus in Thailand
Authors: Fast Arlo W. , Pewnim Thanit , Keawtabtim Rathaya , Saijit Rungarun , Te Franklin T. , Vejaratpimol Renu
Published: April 2007

Wild caught Asian catfish were spawned manually following HCG injection, and a portion of the eggs were subjected to cold‐shock at 4 C for 15 min within 2‐min post‐fertilization. Nuclear diameter measurements of cold‐shocked fish revealed that 96% were triploids (3N), while non‐shocked fish were all diploids (2N). During larval and fry culture (first 26 d), triploid fish mortality was =50%, while diploid mortality was =25%. Following 8‐mo culture in tanks at three stocking densities, triploid fish survival was significantly greater (P < 0.05), than diploids, with 84.0% and 57.3%, respectively. Triploid live weight was also significantly greater than diploids, with 69.2 and 45.9 g averages, respectively. Ninety‐two percent of diploids had welldeveloped gonads after 8 mo; whereas none of the triploids had mature gonads. Gonads were undifferentiated with 31% of the triploids. These sexually undifferentiated fish had greater growth rates than male or female triploids, and greater growth than all diploids. Carcass weight (gutted) of triploids was 95.8% of live weight, compared with 92.5% for diploids. Lastly, triploids had very few deformities compared with diploids, with 1.3% and 17.6%, respectively. Deformities included curved spines, and humped backs just posterior of the head.
Effects of Feed Application Rates on Growth, Survival, and Feed Conversion of Juvenile Snakehead Channa striatus
Authors: Qin Jianguang , Fast Arlo W.
Published: April 2007

Growth, survival and feed conversion ratio of juvenile snakehead Channa striatus were evaluated when fed a dry, formulated feed (50% crude protein) at 24 ± 1 C. Six daily feed application rates were used (0%, 5%, 10%, 15%, 20%, and 30%), as a percentage of fish body weight, with three replicates per treatment. After 29 d, final weights were all significantly greater (P < 0.01) than initial weights, except for the 0% application. Feed applications higher than 5% did not result in increased growth (P > 0.05). Feed conversion ratio was 0.99 at 5% feed application, and 6.3 at 30% feed application. Fish survival was increased by providing formulated diet, but no further improvement was found when feed applications exceeded 5%. Cannibalism was reduced by providing formulated feed, but it was unavoidable when substantial differences in fish size existed, even when feeding ad libitum. Our results indicate that the optimal feed application rate is close to 5% body weight/d for juvenile snakehead.
The Effects of Substituting Selected Oilseed Protein Concentrates for Fish Meal in Rainbow Trout Oncorhynchus mykiss Diets
Authors: Stickney Robert R. , Hardy Ronald W. , Koch Kim , Harrold Robert , Seawright Damon , Massee Kenneth C.
Published: April 2007

Three oilseed protein concentrates (soybean, canola, and sunflower) were evaluated to determine their potential, when supplemented with deficient essential amino acids, to partially or completely replace fish meal in diets fed to rainbow trout Oncorhynchus mykiss. Triplicate aquaria of juvenile trout (average weight of 12 g) were fed the experimental diets for 10 wk, at which time the average weight of the fish was approximately sixfold higher than the initial weight. Average fish weight gains on diets in which the protein component was 100% fish meal; 75% fish meal, 25% soybean protein concentrate; 50% fish meal, 50% soybean protein concentrate; and 75% fish meal, 25% sunflowerseed protein concentrate were not significantly different (P < 0.05). The average weight of fish fed a commercial feed was significantly lower than that of fish fed the 100% fish meal diet, but not significantly different from fish fed the three other formulations mentioned above. Fish fed diets containing 50% fish meal, 50% canola protein concentrate; and 25% fish meal, 75% sunflowerseed protein concentrate had significantly lower average final weights than those of fish fed the other diets. Feed conversion ratio patterns among the dietary treatment groups reflected those of weight gain. Fish survival exceeded 95% on all diets. Apparent protein digestibility coefficients ranged from 79.5% (75% soybean protein concentrate, 25% canola protein concentrate) to 90.6% (100% soybean protein concentrate). The results of this study demonstrated that certain oilseed protein concentrates have good potential as protein sources in rainbow trout feeds when properly supplemented with essential amino acids.
Density‐Dependent Growth and Survival of Penaeus setiferus and Penaeus vannamei in a Semi‐Closed Recirculating System
Authors: Williams A. S. , Davis D. A. , Arnold C. R.
Published: April 2007

Abstract.— Two growth trials utilizing Penaeus vannamei and Penaeus setiferus were conducted at densities of 28.4, 56.8, 85.2, 113.6, 170.4, 227.3 and 284.1/ m2 in an indoor recirculating system. There was an inverse linear relationship between stocking density and growth among both species. The relationship between final weight and stocking density is described by the following linear equation: P. setiferus, Y =−0.00619X ± 4.46, adj. r2= 0.8572;.P. vannamei, Y=−0.00717X ± 7.39, adj. r2= 0.6230. Although the responses in terms of growth depressions were similar, P. setiferus growth was lower than that of P. vannamei. There was an inverse relationship between stocking density and survival for P. setiferus. Survival of P. vannamei was highly variable but was negatively correlated with density. Based on the results of the present study, P. setiferus has a similar tolerance of high density as that of P. vannamei and hence may be suitable for intensive culture systems. However, depressed growth rates of P. setiferus, which do not appear to be due to effects of water quality or density, must be solved if growth rates similar to P. vannamei are to be realized.
Iron Methionine and Iron Sulfate as Sources of Dietary Iron for Channel Catfish Ictalurus punctatus
Authors: Lim Chhorn , Sealey W. M. , Klesius P. H.
Published: April 2007

The dietary iron requirement for normal growth and optimum hematological values and bioavailability was determined for channel catfish Ictalurus punctatus fingerlings using egg‐white based diets supplemented with 0,5,10,20,60, and 180‐mg iron/kg from iron methionine or 20, 60, and 180‐mg iron/kg from iron sulfate. The basal diet which contained 9.2‐mg iron/kg, 34% crude protein and 3.1 kcal of digestible energy/g was fed to channel catfish fingerlings (8.5 g) in triplicate flow‐through aquariums to satiation twice daily for 8 wk. Fish fed the basal diet without iron supplementation exhibited poor growth throughout the 8‐wk period. Fish fed iron‐supplemented diets did not differ with regard to final weight gain. Survival, feed conversion, total blood cell count, mean corpuscular hemoglobin concentration, serum iron, total iron binding capacity, and transferrin saturation were not significantly affected by dietary iron level. Hemoglobin, hematocrit, mean corpuscular hemoglobin, and mean corpuscular volume were significantly lower in fish fed the basal diet. These values were also consistently lower for fish fed diets with 5 and 10‐mg iron/kg from iron methionine. However, differences were not always significant. Results of this study indicate that supplementation of 5‐mg iron from iron methionine was sufficient for growth. However, a supplemental iron level of 20‐mg/kg diet or a total iron level of 30‐mg/kg of diet appeared to be needed for optimum hematological values. Iron methionine and iron sulfate were equally effective in preventing anemia in channel catfish.
Mass Production of Striped Patao Eugerres brasilianus Juveniles in Cuba
Authors: Alvarez‐Lajonchère L. , Sánchez L. Pérez , Molejón O. G. Hernández , Gómez E. Torres
Published: April 2007

Abstract.— Two spawning and larval rearing trials with striped patao Eugerres brasilianus were conducted at Tunas de Zaza, Cuba, to develop a method for experimental‐scale mass production of juvenile fish. Mature striped patao were captured from coastal lagoons in September 1988 and January 1989. Sexually mature females and males were induced to spawn by treatment with human chorionic gonadotropin (HCG). After spawning, eggs were collected and placed in 1.2‐m3 cylindroconical fiberglass incubators at densities of 150 and 200 eggs/L. About 1 h before hatching, eggs were transferred to 5–m3 concrete tanks. Larvae were fed a mixture of marine microalgae, rotifers, copepods, and Artemia nauplii; artificial food was supplied at 30 d post‐hatch as a shrimp diet with 25% protein and 0.1–0.4 mm particles. Fourteen of 20 females spawned after 2 or 3 HCG injections (total dose = 6–10 IU/g body weight). Fecundity was 467–2,167 eggs/g body weight. Egg incubation time in seawater (38–39 ppt salinity) was 15–17 h at 29–30 C and 21–23 h at 25–26 C, with 98–100% hatching rate. The oil droplet and yolk sac were consumed by 3 to 5 d post‐hatch and first food (rotifers) was eaten during second day. High larval mortalities began after the first month. Growth in 39‐ ppt seawater was faster (0.41 ± 0.01 md/d) at 29.1 ± 0.3 C than at 25.2 ± 0.2 C (0.27 ± 0.008 mm/d). Overall survival was 6–12.5% with tinal densities of 5–10 juveniles/L after 48–60 d. A total of 132,000 juveniles was harvested from the two rearing cycles.
Timing of Supplemental Feeding for Tilapia Production
Authors: Diana James S. , Lin C. Kwei , Yi Yang
Published: April 2007

The staged addition of feed to fertilized fish ponds was evaluated by adding fertilizers to 15 ponds stocked with Nile tilapia Oreochromis niloticus, then adding feed at half ad libitum rates once fish in the ponds reached a target weight. Each pond was stocked with 750 fish (3 fish/m2), and each treatment included three ponds with first feeding at (a) 50 g, (b) 100 g, (c) 150 g, (d) 200 g, and (e) 250 g. Ponds in Thailand (at the Ayutthaya Freshwater Fisheries Station, Royal Thai Department of Fisheries) were maintained for 236–328 d until the fish reached 500 g.

Growth was similar for all treatments under fertilizer alone (1.17 g/d) and was also similar when feed was applied (3.1 g/d). Feed application rates averaged 1.17% BW/d, indicating substantial use of natural food. Pond water quality did not deteriorate under supplemental feeding. Feed conversion rates averaged 1.03. Multiple regression indicated that 73.8% of the variance in growth was explained by design variables (feed input and days), while 86.2% of the variance in growth was explained by adding dissolved oxygen content and alkalinity into the equation.

The most efficient system was to grow fish to 100–150 g with fertilizers alone, then add feed. First adding feed (at 50% ad libitum) once fish reached 100 g produced the highest predicted annual revenues ($6,164 per hectare). Results of this experiment indicated that either critical standing crop occurred early (before the first fish sample) or did not occur at all in these ponds.
Effect of Timing of Seed Deployment on Growth and Mortality of Oysters, Crassostrea virginica, Affected by Juvenile Oyster Disease (JOD)
Authors: Barber Bruce J. , Carnegie Ryan B. , Davis Christopher V. , Mook William
Published: April 2007

Abstract.— Mortality of oysters, Crassostrea virginica, caused by Juvenile Oyster Disease (JOD) has been a chronic problem the northeastern United States since 1988. To assist in identifying potential health management options, the effect of time of spawning and deployment of oysters on resultant growth and mortality was examined in the Damariscotta River, Maine. Broodstock oysters from a line selected for fast growth were spawned at 2‐wk intervals between 28 March and 19 July 1995. Duplicate groups of juvenile oysters from each spawn were deployed in floating trays between 23 May and 31 August. Mortality and size of all cohorts were determined from late June to early December. Cumulative mortality of oysters was related to the timing of deployment. Cohorts placed in the river before June or after mid‐August had cumulative mortalities of 20% or less. Oysters deployed between 8 June and 18 August had cumulative mortalities ranging from 64–96%. Growth of all cohorts was rapid immediately after deployment but decreased once JOD began to have an effect. Final size of oysters was directly related to age. This study determined that seed oysters placed in the Damariscotta River between June and mid‐August will experience high mortality and low growth. Potential management options to reduce JOD impact include 1) early spawning and deployment in May, ensuring that a mean shell height >25 mm is reached prior to August and 2) late spawning and deployment after mid‐August to avoid exposure to JOD.
Efficacy of Trenbolone Acetate in Sex Inversion of the Blue Tilapia Oreochromis aureus
Authors: Galvez John I. , Morrison John R. , Phelps Ronald P
Published: April 2007

Abstract.— Trenbolone acetate (TBA) is a synthetic anabolic androgenic steroid approved in the United States as a growth promoter for beef cattle. Pooled populations of blue tilapia Oreochromis aureus with more than 98% males were produced by feeding diets containing TBA. This hormone effectively inversed the sex of blue tilapia when doses of 25–100 mg/kg of diet were fed for 28 d. Fish treated with 60 mg of 17‐alpha‐methyltestosterone (MT)/kg of feed resulted in 88.7% males. The percentage of male tilapia masculinized with TBA was significantly higher (P < 0.05) than with MT. Intersex fish were found in both control and hormone‐treated groups, and were significantly more common (P < 0.05) in the MT‐treated batches. Survival, feed conversion ratio, and average weight of O. aureus fry fed diets containing either TBA, MT or no hormone were not different (P > 0.05) at the end of the 28‐d treatment period.
Effect of 17α‐Methyltestosterone and 17α‐Hydroxyprogesterone on the Quality of White ShrimpPenaeus vannameiSpermatophores
Authors: Alfaro Jorge
Published: April 2007

Abstract.—Controlled reproduction of penaeid shrimp requires a better utilization of males by sperm quality monitoring and sperm quality improvement. Spermatophores of white shrimpPenaeus vannameiwere improved, in terms of increased sperm count, spermatophore weight, and a reduced incidence of sperm abnormalities by a single injection of 17α‐methyltestosterone at 0.01 or 0.1 μg/g body weight. 17α‐hydroxyprogesterone did not induce a significant improvement in spermatophore quality. These findings indicate that a steroid injection program should be evaluated as a practical way of improving spermatophore quality in commercial operations.
The Effect of Temperature on Production of Gonads by the Sea Urchin Strongylocentrotus franciscanus Fed Natural and Prepared Diets
Authors: McBride Susan C. , Pinnix William D. , Lawrence John M. , Lawrence Addison L. , Mulligan Timothy M.
Published: April 2007

Strongylocentrotus franciscanus (248 ± 76 g wet body weight, mean and standard deviation) were maintained in the laboratory at 12.9 and 16.1 C and fed either Nereocystis luetkeana or a prepared feed for 4 mo (July through October). The size and histological condition of the gonads of an initial sample, the experimental animals, and a sample from the commercial fishery were evaluated. The gonad index of experimental S. franciscanus increased from an initial 3.4%± 1.4 to 19.2%± 3.3 (mean and standard deviation) for the four treatments. The feeding rate was greater for individuals fed N. luetkeana and for both foods at the higher temperature. Gonad production was not significantly different among the experimental treatments, indicating the prepared feed was nutritionally superior to the algal diet and an increase in catabolism at the higher temperature balanced the increase in food intake. Histological preparations determined the urchin gonads developed from an initial spent condition to the premature stage for both experimental and fishery samples, indicating neither food or temperature affected gametogenesis.
Net Absorption of Dietary Phosphorus from Various Inorganic Sources and Effect of Fungal Phytase on Net Absorption of Plant Phosphorus by Channel Catfish Ictalurus punctatus
Authors: Eya Jonathan C. , Lovell Richard T
Published: April 2007

Year‐2 channel catfish (average weight 765 g) were fed a commercial‐type, all‐plant diet containing supplemental phosphorus (0.40%) from one of various sources, or fungal phytase (1,000 and 3,000 units), in 1‐m3 circular raceways for 21 d at a temperature of 28–30 C. Subsequently, net absorption of phosphorus from the diets was determined by the chromic oxide indicator method in which feces were collected from the rectum. Net absorption of the supplemental phosphorus was corrected for the absorbed residual phosphorus in the basal diet. Net absorption coefficients for monosodium phosphate, monoammonium phosphate, finely ground defluorinated rock phosphate and monocalcium phosphate were 88.6, 85.4, 81.7, and 81.2%, respectively, and were not significantly different. Net absorption coefficient for dicalcium phosphate was significantly lower, 74.8%, but was significantly higher than those for coarsely ground defluorinated rock phosphate and tricalcium phosphate, which were 55.1 and 54.8%, respectively. These data are in general agreement with relative bioavailability values based on growth response for channel catfish determined in other research, and should be appropriate for determining available phosphorus allowances in commercial feeds and establishing phosphorus budgets in aquaculture feeding operations. The net absorption of phosphorus from the all‐plant basal diet was 31.2% and increased significantly to 55.1 and 62.5% with the addition of 1,000 and 3,000 units of fungal phytase, respectively.
A Preliminary Bacteriological Study of Refrigerated Channel Catfish Sperm
Authors: Jenkins Jill A. , Tiersch Terrence R.
Published: April 2007

Abstract.— This study was designed to simulate conditions encountered routinely during refrigerated storage of channel catfish sperm. Sperm samples were stored at 4 C in non‐sterile and sterile Hanks' balanced salt solution (HBSS). Non‐sterile HBSS was prepared with distilled water stored for 2 wk in a plastic carboy prior to use. Observations were made on the frequency and abundance of bacteria in samples, and on changes in sperm motility and quality. Sperm samples stored in non‐sterile HBSS had a complete loss of motility within 72 h. Samples maintained in sterile HBSS showed an initial decrease in motility between 48 and 72 h, and a complete loss of motility within 10 d. Quality of the sperm in each buffer decreased as motility decreased; morphologic changes and reduced motility of sperm were coincident with increased bacterial numbers. Bacteria were cultured on tryptic soy agar and Pseudomonas F agar (PFA) by spread‐plating 10–μL aliquots from each sample onto bacteriologic media and incubating for 5 d. The dominant bacteria observed were members of the genus Pseudomonas, representing 67% of the total bacteria identified. The dominant pseudomonad (Pseudomonas sp.) cultured from sperm samples stored in sterile buffer produced caseinase, lecithinase, and was β‐hemolytic, whereas the dominant bacteria (P. putida) cultured from samples stored in the non‐sterile buffers did not. Highly motile pseudomonads, present in two samples stored in sterile buffer, colonized below the surface of the PFA media at 4 C. The attributes of the bacterial contaminants that likely contributed to the decrease in sperm quality were production of extracellular enzymes, consumption of oxygen, and a high level of motility. Potential sources of degradative bacteria were commensal flora of channel catfish and the water used in preparing the storage buffer.
Growth, Survival, and Biochemical Composition of Freshwater Prawns Macrobrachium rosenbergii Fed Natural Food Organisms Under Controlled Conditions
Authors: Tidwell James H. , Schulmeister Greg , Mahl Cathy , Coyle Shawn
Published: April 2007

Under production conditions freshwater prawns Macrobrachium rosenbergii are supplied nutrients by a combination of prepared diets and natural pond organisms. For maximum production efficiency and profitability it is important that the nutritional contributions of natural foods be identified and quantified. In this study the relative importance of forage organisms previously identified as important natural foods for prawns in ponds were evaluated under controlled conditions. Juvenile prawns (average weight 1.80 ± 0.06 g) were stocked into 18 37.5‐L aquaria at a density of 10 prawns per tank. The six dietary treatments tested were: 1) unfed (negative control); 2) commercially prepared diet (positive control); 3) oligo‐chaetes; 4) chironomids; 5) zooplankton; and 6) a combination of the latter three. Each treatment was evaluated in triplicate aquaria for 7 wk. The growth rate of prawns in the unfed treatment was statistically lower than in fed treatments (P < 0.05). There were no significant differences (P > 0.05) between growth rates and survivals among prawns in the five fed treatments. Selective retention of arachidonic acid (20:4n‐6), eicosapentanoic acid (22: 5n‐3), and docosahexanenoic acid (22:6n‐3) in unfed prawns likely indicates the relative nutritional importance of these fatty acids. Comparisons of whole‐body fatty acid and amino acid concentrations of prawns and food organisms indicate that zooplankton and oligochaetes may have the most appropriate biochemical compositions as prawn food sources.
Influence of the Dietary Level of Iron from Iron Methionine and Iron Sulfate on Immune Response and Resistance of Channel Catfish to Edwardsiella ictaluri
Authors: Sealey Wendy M. , Lim Chhorn , Klesius P. H.
Published: April 2007

Channel catfish Ictalurus punctatus fingerlings were fed purified diets supplemented with iron at levels of 0, 20, 60, and 180 mg/kg from iron sulfate (FeS) or 5, 10, 20, 60, and 180 mg/kg from iron methionine (FeM) in triplicate tanks for 8 wk. Fish were then divided into two groups and subjected to different assays to measure disease resistance and individual immune functions. Representative fish from each dietary treatment were challenged by bacterial immersion with virulent Edwardsiella ictaluri, and mortality due to enteric septicemia was recorded. Other fish were immunized with 0.2–mL formalin‐killed E. ictaluri and boosted 21 d post‐immunization. Antibody response was determined by FAST‐ELISA. Chemiluminescent and chemotaxis assays were performed using peritoneal macrophages. Supplementation of the diet with various levels of iron from FeS or FeM did not significantly affect antibody production. Chemotactic migration by macrophages was depressed in iron‐deficient fish and a level of 60 mgkg from either FeS or FeM provided the highest chemotactic indexes. A deficiency of dietary iron was found to increase mortality of channel caffish due to enteric septicemia of catfish (ESC). However, more studies should be conducted to better understand the effects of sources and levels of dietary iron on immune responses and disease resistance in channel caffish.
The Toxicity of Hydrogen Peroxide to Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout Oncorhynchus clarki Fry and Fingerlings
Authors: Arndt Ronney E. , Wagner Eric J.
Published: April 2007

Fungal and parasitic infections of fish can significantly impact the survival of cultured fish. Formalin is currently used to control such infections; however, concern has arisen over its safety to users and to the environment. Hydrogen peroxide has been designated as a low priority fungicidal drug by the United States Food and Drug Administration (FDA), yet, little information is available on treatment concentrations or its toxicity to trout. Rainbow trout Oncorhynchus mykiss and cutthroat trout Oncorhynchus clarki fry and Angerlings were exposed to hydrogen peroxide concentrations of 0, 70, 170, 280, 420 and 540 ppm for 30, 60 or 120 rnin at 15 C to determine the chemical's toxicity. Rainbow trout fry and fingerlings experienced elevated mortalities (>20%) during treatments using 420 and 540 ppm for 30 min; 280, 420 and 540 ppm for 60 min; and >170 ppm for 120 min. Cutthroat trout fry experienced elevated mortalities (>23%) during treatments using 540 ppm for 30 min; 420 and 540 ppm for 60 min; and >170 ppm for 120 min. Cutthroat trout fingerlings experienced elevated mortalities (>60%) during treatments using 540 ppm for 60 min and >280 ppm for 120 min. No control mortalities were encountered for both life stages of either species. The lethal concentrations (LC50) of both age classes and species for each of the three durations ranged from 514–636 ppm for 30 min treatments, 322–506 ppm for 60 min treatments, and 189–280 for 120 min treatments. Mortalities for all four toxicity tests which occurred during a 96‐h post‐treatment period were centered around the following treatments: 30 min, 540 ppm; 60 min, 280–540 ppm; 120 min, 170 ppm. Tissue damage to gills was found only among fish that did not survive the initial chemical exposure. Test concentrations proved to be relatively stable during a 24‐h period, retaining better than 85% of their original strength for all five dilutions. At a water temperature of 15 C concentrations should not exceed 280 ppm for a 30‐min treatment.
Enhancement of Gonad Production in the Sea Urchin Loxechinus albus in Chile Fed Extruded Feeds
Authors: Lawrence John M. , Olave Sergio , Otaiza Ricardo , Lawrence Addison L. , Bustos Eduardo
Published: April 2007

Loxechinus albus were fed algae (Macrocystis pyrifera and Ulva sp.) and two feeds prepared by extrusion (one containing kelp). Results were the same for individuals maintained in suspended cages in the sea and in aquaria on land. Gonads increased in size in individuals fed extruded feeds and decreased in individuals fed algae during the spawning season. Gonads increased ca. four‐fold in size in individuals fed the extruded feeds during the post‐spawning season, much greater than those fed algae. Individuals fed extruded feeds had a lower feeding rate than individuals fed algae on a wet‐weight but not on a dry‐weight basis. The extruded feed supports gonadal growth more than natural food and has potential for use for aquaculture of sea urchins.
Effects of Stocking Density and Monosex Culture of Freshwater Prawn Macrobrachium rosenbergii on Growth and Production in Concrete Tanks in Saudi Arabia
Authors: Siddiqui Abdul Qayyum , Al‐Hafedh Yousef S. , Al‐Harbi Ahmed H. , Ali Seikh A.
Published: April 2007

Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m2, grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m2 (29.6 9). and lowest at 20 prawns/m2 (17.4 g). Total yield increased from 135 g/m2 (1,350 kg/ha) at a density of 5 prawns/m2 to 261 g/m2 (2,610 kg/ha) at density 15/mz to 245 g/m2 (2,450 kg/ha) at 20/mz. Feed conversion ratios were high and ranged from 3.7 (5 prawns/m2) to 5.6 (20 prawns/m2).

In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m2 for 112 d, the all‐male population had the best growth performance and feed conversion ratio, followed by the mixed‐sex and all‐female populations. The all‐male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m2 (1,590 kg/ha); the mixed‐sex population had 90% marketable prawns and the yield was 135 g/mz (1,350 kg/ha); and the all‐female population had 75% marketable prawns with an average yield of 108 g/m2 (1,080 kgha).
Optimal Dietary Protein Concentration for Hybrid Tilapia Oreochromis niloticus × O. aureus Fed All‐Plant Diets
Authors: Twibell Ronald G. , Brown Paul B.
Published: April 2007

There are several estimates of the optimal dietary crude protein concentration for juvenile tilapia fed high quality animal proteins or mixtures of animal and plant derived feedstuffs. In the present study, the optimal dietary crude protein concentration for hybrid tilapia Oreochromis niloticus × O. aureus reared in glass aquaria was determined using diets free of fish meal. Further, initial weight of fish was approximately 21 g, which is the beginning of the growout phase of many commercial operations. The diets contained primarily corn co‐products and soybean meal as the sources of amino acids, and were formulated to provide 24, 26, 28, 30, 32 or 34% crude protein. The diets were fed to quadruplicate groups of tilapia for 10 wk. Increasing concentrations of dietary crude protein resulted in proportional improvements in weight gain and feed efficiency up to 30% dietary crude protein. Fish fed 24% dietary crude protein exhibited significantly reduced weight gain compared to fish fed 28–34% dietary crude protein. Protein efficiency ratio (PER) of tilapia was unaffected by dietary crude protein concentration. However, fish fed 28% crude protein exhibited numerically higher PER (2.58) than fish fed other levels of crude protein. Muscle crude protein levels were lower in fish fed diets containing 24–28% crude protein than in fish fed 30% and higher concentrations. Quadratic regression analyses of weight gain and feed efficiency data indicated the optimal dietary crude protein concentration to be 29.65% and 28.33%, respectively, while broken line analyses indicated 27.5 and 27.3%, respectively. Based on weight gain, feed efficiency, PER, and proximate composition data, the authors recommend 28% dietary crude protein as the minimum for hybrid tilapia fed all‐plant diets and reared in tanks.
Coliform Organisms in Waters of Channel Catfish Ponds
Authors: Boyd Claude E. , Tanner Margaret
Published: April 2007

Water from 48 channel catfish Ictalurus punctatus ponds at Auburn and Greensboro, Alabama, USA, usually contained less than 1,000 total coliform and 200 fecal coliform bacteria per 100 mL. There were no sources of human fecal matter to ponds. Also, the fecal coliform: fecal streptococci ratio was less than 1.0 and typical of fecal contamination by warm‐blooded animals other than humans. The abundance of coliforms was greater in spring and summer than in fall and winter in catfish ponds and sportfish ponds at Auburn, Alabama. In spite of high organic matter inputs in feed, catfish ponds had no greater abundance of coliforms than sportfish ponds.
Growth Rate, Feed Conversion, and Body Composition of Catla catla, Labeo rohita, and Cirrhinus mrigala Fry Fed Diets of Various Carbohydrate‐to‐Lipid Ratios
Authors: Erfanullah  , Jafri A. K.
Published: April 2007

Effects of dietary carbohydrate‐to‐lipid (CHO : L) ratios on the growth rate, conversion efficiencies, and body composition were studied in the Indian major carp fry Catla catla, Labeo rohita, and Cirrhinus mrigala. Six isonitrogenous (40% crude protein) and isocaloric (3.46 kcal metabolizable energy/g) semi‐purified diets, with CHO: L ratios of 0.02, 0.60, 1.54, 3.38, 8.93, and 43.00 were fed to triplicate groups of fish in 70‐L flow‐through (1.5–2.0 L/min) indoor circular troughs. Fish were fed to apparent satiation (about 10% body weight), 6 d/wk, twice daily at 0800 and 1600 h for 6 wk. Fish growth rates differed significantly (P < 0.05) with CHO: L ratio in the diets. Maximum weight gain (%) and specific growth rate (SGR %) were observed in C. catla and L. rohita fed a diet with 36% carbohydrate and 4% lipid, corresponding to a CHO: L ratio of 8.93. In C. mrigala, highest weight gain (%) and SGR (%) were noted in fish fed 27% carbohydrate and 8% lipid, corresponding to a CHO: L ratio of 3.38. In all the species, fish fed either diet with the lowest (0.02) or the highest (43.00) CHO: L ratio tended to have significantly lower (P < 0.05) growth and conversion efficiencies. Percentage of dry matter and whole‐body lipid of fish significantly (P < 0.05) increased as CHO: L ratio decreased. However, whole‐body crude protein content of fish significantly (P < 0.05) increased as CHO : L ratio increased. The results of this study indicate that the Indian major carp fry efficiently utilize carbohydrate for energy, and excess dietary lipid resulted in increased lipid accumulation in the body.