bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of Pseudoalbinism in Flatfish: An Association Between Pigment Cell and Skin Differentiation
Authors: Seikai Tadahisa , Matsumoto Jiro
Published: April 2007

Two groups of flounder P. olivaceus larvae were reared under different conditions to provide either normally pigmented or pseudoalbinic metamorphosed juveniles. The process of the differentiation of skin and pigment cells during postembryonic development was analyzed by means of histological, histochemical and immunofluorescent assay methods. In parallel with these assays, the differentiation of pigment cells was examined with the use of organ and cell culture in vitro. The results obtained strongly suggested that pseudoalbinism was evoked as a result of disruption of the mechanisms that controlled the establishment of asymmetric skin structures during metamorphosis.
A Review of Di‐n‐Butylphthalate in the Aquatic Environment: Concerns Regarding Its Use in Salmonid Aquaculture
Authors: Burridge L. E. , Haya K.
Published: April 2007

The presence and effects of di‐n‐butylphthalate (DBP) in aquatic environments are reviewed. Particular attention is paid to the use of DBP as a solvent in the pesticide formulation, Aquagard®, used to treat salmonids against external parasites at aquaculture sites in Europe. DBP is sparingly soluble in water, is readily metabolized by fish, and has a high lethal threshold for aquatic organisms. It is, however, lipophilic, persistent in aquatic sediments, and is listed as a priority pollutant by the governments of Canada and United States. The dissemination of this compound directly to water raises several concerns which should be addressed by further research and increased monitoring.
Evaluation of Soybean Proteins as Replacements for Menhaden Fish Meal in Practical Diets for the Red Drum Sciaenops ocellatus
Authors: Davis D. Allen , Jirsa D. , Arnold C. R.
Published: April 2007

A series of growth trials was conducted to evaluate the use of soy protein as a replacement for fish protein in isonitrogenous practical diets for juvenile red drum Sciacnops ocellatus. Feeds were offered at or in excess of satiation to juvenile red drum maintained at 26–28 C and a salinity of 25–35 ppt. In the first growth trial, red drum were offered one of four diets containing graded levels of menhaden fish meal, replacing solvent‐extracted soybean meal and soy‐protein isolates. Differences in weight gain, survival and feed efficiency ratios of the fish corresponded to increases in fish meal content of the diets. Due to poor performance of the fish maintained on the low (15%) fish meal diet, a methionine supplement was introduced into this diet at the midpoint of the growth trial. A positive increase in growth indicated a dietary deficiency of methionine and/or total sulfur amino acids in the unsupplemented diet. A positive response to dietary fish meal also occurred in the second growth trial despite the supplementation of L‐methionine in the test diets. In low fish meal diets the utilization of solvent extracted soybean meal or a soy‐protein isolate resulted in similar growth responses. Hence, the presence of an antinutrient did not likely cause reduced growth rates. In the third feeding trial, weight gain also increased with increasing fish meal content of the diet despite the equalization of digestible protein and selected amino acids. There were no significant differences in whole‐body compositions which indicated similar biological value of the diets (protein digestibility, amino acid balance and energy availability). The singular deletion of fish‐solubles, glycine, lysine and methionine from the diet containing the lowest level of fish meal (10 g/100 g diet) did not result in significant changes in weight gain. This indicated that these components did not add to the nutritive value and/or palatability of this formulation. The final experiment was designed to evaluate the response of red drum to a control diet (high fish meal) as compared to a low fish meal diet with and without potential attractants/palatability enhancers. Weight gain and feed efficiency ratios of fish offered the low fish meal diet supplemented with seafood flavor or fish flavor #2 were not significantly different from the control (high fish meal diet). Based on the results of this study, with suitable formulation restrictions, soy protein is acceptable for inclusion in practical diet formulations for red drum. However, soy protein itself does not appear replete in sulfur‐containing amino acids and does not have acceptable palatability properties. Consequently, feeds containing reduced levels of marine proteins could require suitable attractants and/or amino acid supplements.
Semi‐Intensive Commercial Grow‐Out of Penaeus vannamei Fed Diets Containing Differing Levels of Crude Protein During Wet and Dry Seasons in Honduras
Authors: Teichert‐Coddington David R. , Rodriguez Rigoberto
Published: April 2007

Shrimp were grown under ideal management conditions during two distinct seasons of the year at stocking densities used most often in Honduras with the objective of evaluating the usefulness of high protein diets. A randomized design in 2 × 2 factorial arrangement was used to test a diet composed of either 20 or 40% crude protein in earthen ponds that were stocked with juvenile Penaeus vannamei at 5 to 11/m2. The study was repeated during wet and dry seasons. Dietary protein level had no significant effect (P > O.05) on survival, yield, or average weight of shrimp at either density during either season. Higher stocking rates yielded significantly greater shrimp production during both seasons. Mean shrimp weight in high density ponds was significantly lower than mean shrimp weight in low density ponds during the wet season, but there was no significant weight difference because of stocking density during the dry season. Mean survival was significantly lower at the higher stocking rate during the dry season. Net income was negative during the dry season, particularly at the high stocking density. Mean production was 240% greater in the wet season than in the dry season. Diets offered P. vannamei stocked at 5 to 11/m2 should contain no more than 20% protein, regardless of season. Higher dietary protein levels increase costs and waste nitrogen without resulting in greater shrimp yields. The high stocking density might increase profitability in the wet season, but long term sustainable production may be more feasible at lower stocking rates because of reduced nutrient wastes.
Design Procedure for Hooded Surface Oxygen Absorption Systems
Authors: Watten Barnaby J.
Published: April 2007

A design procedure addressing effluent total dissolved gas pressure limits along with standard performance indicators such as oxygen absorption efficiency (kg absorbed/kg applied), and transfer efficiency (kg/kW.h), is presented for surface agitation equipment operating in an oxygen‐enriched atmosphere. Application of this contactor type in closed culture systems is attractive given its insensitivity to biological fouling and ability to operate without the need for a significant hydraulic gradient. Performance algorithms were developed through application of chemical reactor theory, Henry's Law and the Ideal Gas Law. In the analysis, gas and liquid phases were treated as being homogeneous. The design steps presented are unique in that required mass transfer coefficients (KLa), operating pressures (CP), and oxygen feed rates (G/L) are calculated for target changes in both dissolved oxygen and nitrogen without the use of iterative numerical procedures. A second calculation sequence establishes the sensitivity of system performance to changes in G/L when CP and KLa are known.
Predicting Crawfish Molting with Machine Vision
Authors: Timmermans Toine , Sistler Frederick E. , Lawson Thomas B.
Published: April 2007

The objective of this project was to develop a vision system that could predict when crawfish will molt. Different sections of the crawfish shell were examined to determine how the color changed as the time of molting approached. A strip on the tail section of the crawfish showed the greatest, most consistent color change. The average red/green × red/blue ratio decreased for every crawfish as the molting time approached. Using this ratio as a predictor, it was possible to predict the molting of a crawfish within 3 d with an accuracy greater than 80%. The limitation on accuracy was primarily the result of the large variations in natural shell color among the crawfish.
Egg Water Induced Reaction and Biostain Assay of Sperm from Marine Shrimp Penaeus vannamei: Dietary Effects on Sperm Quality
Authors: Wang Qingyin , Misamore Michael , Jiang Charlie Q. , Browdy Craig L.
Published: April 2007

Reproductive performance was evaluated for sexually mature male Penueus vannamei fed one of four diets: 1) commercial 40% protein shrimp growout diet; 2) 100% squid; 3) 50% squid, 25% bloodworms and 25%Artemia; and 4) starvation. Spermatophores were ejaculated manually from tagged males at stocking and every 12 d thereafter. For each half of the compound spermatophore, weight and sperm count were determined. Four methods were used to assay the sperm quality: 1) gross morphology (GM); 2) trypan blue stain (TB); 3) acridine orange stain (AO); and 4) egg water induced reaction (EW). The reaction induced when P. vannamei sperm are exposed to conspecific egg water is grossly similar to that observed in vivo at the surface of the freshly spawned eggs from naturally mated females. Little correlation was found between spermatophore weight and sperm count. The best correlation was found between GM and AO (r2= 0.859, P < 0.01). Many morphologically abnormal sperm did not stain with TB. For most of the spermatophores evaluated; over 80% of the sperm were morphologically normal, were unstained with TB, and were immediately fluorescing light green when stained with AO. When exposed to egg water, sperm from these apparently good quality spermatophores yielded mixed results. The analysis of dietary effects on spermatophore quality were equivocal. Although a significant decline in body weight, spermatophore weight, and sperm count were observed in the starvation treatment as compared to maturation and squid diets, no significant differences were observed in MY of the sperm quality assays.
Chemical Budgets for Organically Fertilized Fish Ponds in the Dry Tropics
Authors: Green Bartholomew W. , Boyd Claude E.
Published: April 2007

Chemical budgets were determined for nitrogen, phosphorns, dissolved oxygen and chemical oxygen demand for three 0.1‐ha earthen ponds stocked withOnwchrornis nilotieusat the El Carao National Fish Culture Research Center, Comayagna, Honduras, for two 150‐d culture periods, corresponding to the rainy and dry seasons. Layer chicken litter was added to ponds weekly at 500 kg dry matter/ha. Concentrations of nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) in pond water increased during each season. No significant seasonal differencea in concentrations of water quality variables were observed. Chicken litter added to ponds represented 92–94% of N input, 93–95% of P input, and 43–52% of COD input. Photosynthesis by phytoplnnkton provided 47–56% of COD and 98% of dissolved oxygen (DO) added to ponds. Net inward diffnsion of oxygen added 1.2–1.5% of total DO. Regulated inflow was a minor source of nutrients, and contributed 3–4% of input N, 3–4% of input P, 1% of COD input, and 1% of DO input. Nutrient inputs from rain were ≤1% of total for each nutrient. Fish harvest accounted for 18–21% of total N, 16–18% of total P and 2% of COD added to ponds. Community respiration accounted for 48–57% of COD and 99.5% of DO added to ponds. Nutrient losses in pond effluent at draining were: 7–9% of total N, 29–37% of total P and 2–3% of COD. While measured gains exceeded measrued losses, significpntly greater N, P and organic matter concentrations in pre‐drain samples indicated pond mud was a major sink for added nutrients, accumulation in mud represented 70% of total N, 35–40% of total P, and 38–46% of COD.
Winter Field Trials of Enrofloxacin for the Control of Aeromonas salmonicida Infection in Salmonids
Authors: Hsu H.‐M. , Bowser P. R. , Schachte J. H. , Scarlett J. M. , Babish J. G.
Published: April 2007

The antimicrobial enrofloxacin (Baytril®, Bayer) was evaluated under field conditions in the winter months for treatment of clinical Aeromonas salmonicida infections in salmonids by feeding medicated diets. Two trials in which lake trout Salvelinus namaycush were treated with enrofloxacin at 10mg/kg per d for 10d resulted in reduced mortalities when compared to non‐medicated controls. A third trial in which Atlantic salmon Salmo salar were treated required 20d for the fish to consume the 10d medicated ration, due to poor feeding. This resulted in an effective dose of 5mg/kg per d for 20d. In spite of the lower feeding activity, a reduction in mortalities in medicated fish was observed. Tissue concentrations of drug were in excess of minimum inhibitory concentrations of the drug for the A. salmonicida isolates tested.
Effects of Long‐Term Feeding of Cottonseed Meal on Growth, Testis Development, and Sperm Motility of Male Channel Catfish Ictalurus punctatus Broodfish1
Authors: Robinson Edwin H. , Tiersch Terrence R.
Published: April 2007

The effects of long‐term feeding of cottonseed meal on growth, testis development, and sperm motility of male channel catfish Ictulurus punctatus were studied. Brood‐sized male channel catfish were stocked into 0.04‐ha earthen ponds in April 1992 at the rate of 120 fish per pond. The fish were fed a diet (32% protein floating catfish feed) containing either 0, 25, 375, or 52% cottonseed meal to satiation daily, except for winter months when fish were fed on days when the water temperature was 15 C or above. Fish were harvested in July 1994. Feed consumption was similar for fish regardless of dietary treatment. Feed conversion was higher for fish fed the two highest levels of cottonseed meal and weight gain was depressed in these groups. Testis weight, gonosomatic index, and sperm motility were not negatively affected by high levels of dietary cottonseed meal indicating that reproductive capacity was not diminished. Thus it wonld appepr that up to 52% cottonseed meal could be used in the diets of brood‐sized channel catfish unless maximum gain is important. In a practical situation, growth rates of brood‐sized channel catfish are not as important as reproductive performance.
Apparent Digestion Coefficients and Metabolizable Energy of Feed Ingredients for Rainbow Trout Oncorhynchus mykiss
Authors: Smith Robert R. , Winfree Robert A. , Rumsey Gary W. , Allred Anila , Peterson Montie
Published: April 2007

More than 50 feedstuffs used or of potential use in diets for rainbow trout Oncorhyndus mykiss were compared through metabolism chamber trials. Testing included determination of apparent digestibility and metabolic energy for a wide variety of ingredients, including fish and animal meals, vegetable proteins, and single cell protein products. Testing involved feeding individual 200–300‐g fish contained in replicate chambers, from which feces, urine, and gill excreta were collected seg arately and analyzed for residual nitrogen and energy. For comparison, several products previously tested at this or other laboratories were re‐evaluated at dietary concentrations of 25, 50, or 100%.
Effects of Temperature on the Uptake and Depuration of 2‐Methylisoborneol (MIB) in Channel Catfish Ictalurus punctatus
Authors: Johnsen Peter B. , Lloyd Steven W. , Vinyard Bryan T. , Dionigi Christopher P.
Published: April 2007

The microbial metabolite 2‐methylisoborneol (MIB) imparts a muddy off‐flavor to channel catfish Ictalurus punctatus. Uptake and depuration of MIB from fish are important considerations in the design and implementation of systems to remove off‐flavors from fish prior to processing. The kinetics of MIB uptake by channel catfish were determined by placing fish in 6.5, 14.0, 25.0, and 34.0 C water containing approximately 1.0 μg/L chemically‐synthesized MIB. Fish were sacrificed following 0, 2, 4, 8, and 24 h exposure to MIB. Fillet tissue samples were subjected to gas chromatographic and fat content analysis. The model for MIB uptake was:

MIB in fillet tissue (μg/kg) =−0.61 ± 4.2 [log(h± 1)] ± 0.0076(T) (h) ± 0.089(T),

where h is the duration of exposure to MIB in hours and T is the water temperature in degrees C. The model accounted for 74% of the total variation observed in the tissue MIB concentrations and indicated that the fillet fat content was not strongly correlated with MIB uptake. To investigate the depuration of off‐flavors, exposure to MIB was halted. Tissue samples were obtained 4, 8, 24, 48, and 72 h from fish held at 6.5, 14.0, 25.0, and 34.0 C. These data yielded the model:

MIB in fillet tissue (μg/kg) = 3.6 ± 0.176(T) – 2.06 [log(h± 1)] – 0.00296(T) (h) ± 0.197 (% fat),

where h is the duration of exposure to MIB in hours, T is the water temperature in degrees C, and % fat is the % fat in the fillet tissue. The model accounted for 67% of the total observed variation in tissue MIB concentrations. Reducing the fat content of fish and optimizing water temperatures may augment MIB removal from fish tissues prior to processing.
Thyroid Hormones and Their Influences on Larval Performance and Incidence of Cannibalism in Walleye Stizostedion vitreum1
Authors: Hey Jane , Farrar Eugenia , Bristow Brian T. , Stettner Craig , Summerfelt Robert C.
Published: April 2007

Thyroid hormones, 3,5,3′,5′‐ tetraiodothyronine (T4) and 3,5,3′‐ triiodothyronine (T3) have been found in the eggs of several teleost species and are potential regulators of larval development, growth, and survival. The purpose of the present study was to determine whether natural variation of T3 and T4 in the eggs of six stocks of walleye, five wild stocks from Kansas, Iowa, Wisconsin, Minnesota, and North Dakota, and a semi‐domesticated stock from an Ohio fish hatchery, have an effect on larval performance in mass culture. Immersion studies were conducted with samples of larvae from four of the same stocks at exposure concentrations of 0.01, 0.05, and 0.1 ppm of T3 and T4. Natural egg concentrations of T3 (range from 0.70 to 1.5 ng/g wet weight of egg) were not significantly different among stocks. Although means of T4 concentration among stocks were significantly different (range 0.53–9.27 ng/g), the difference was caused by the exceptionally high concentration for the Wisconsin stock (9.27 ng/g ± 2.20). Performance measures of the Wisconsin stock (Mississippi River), were not related to T4 concentration in that stock. In spite of similarity in concentrations of T4 and T3 in the eggs, there were significant performance differences among the stocks (survival to 21 d, gas bladder inflation, viability, cannibalism, and growth). The immersion studies, however, revealed a significant difference in incidence of cannibalism and temperature units (TU) to 50% mortality (i.e., survival) between the control groups and treatment groups exposed to 0.01 to 0.1 ppm T3 and T4. Survival was extended more than 2‐fold longer in larvae immersed in T3 compared with T4. The immersion study indicated that thyroid hormones are potentially regulators of walleye development, but further investigations are needed to determine reasons for differences in larval performance based on natural concentrations in the egg and artificial exposure (immersion).
Effects of Dietary Energy: Protein Ratio and Stocking Density on Growth and Survival of the Common Snapping Turtle Chelydra serpentinal1
Authors: Mayeaux Maxwell H. , Culley Dudley D. , Reigh Robert C.
Published: April 2007

Although the common snapping turtle Chelydra serpentina is cultured commercially in the United States, little information is available on nutritional and culture requirements. This study was conducted to evaluate the effects of dietary energy: protein ratio and stocking density on survival, growth, feed consumption, feed conversion, liposomatic index, dress‐out percentage, and productive protein value of cultured, common snapping turtles. Hatchling turtles were stocked at 29 and 58 animals/m2 and fed one of seven prepared diets. Six diets contained 30, 35, or 40% protein at two digestible energy (DE) levels (7 or 9 kcal DE/g protein); the seventh was a reference diet (66% protein and 5 kcal DE/g protein) formulated to equal or exceed the whole‐body essential amino acid composition of wild, common snapping turtles. Turtles stocked at 58/m2 exhibited greater mortality, lower weight gain, higher feed consumption, less‐efficient feed conversion, lower liposomatic index, and lower productive protein value than turtles stocked at 29/m2 (P < 0.05). The reference diet produced the greatest weight gain (P < 0.001). The superior performance of turtles fed the reference diet suggests that: 1) the protein (amino acid) content and/or energy: protein ratio of the reference diet was superior to that of the other diets tested; 2) improvements in growth parameters can be made with dietary manipulation; and 3) high levels of plant protein can be used in prepared, snapping turtle diets.
Neurotoxin Production by a Chloromonad Fibrocapsa japonica (Raphidophyceae)
Authors: Khan Saleha , Arakawa Osamu , Onoue Yoshio
Published: April 2007

The ichthyotoxicity and toxin composition of a red‐tide producing chloromonad Fibrocapsa japonica (Toriumi and Takano) were examined. The flagellate showed the highest toxicity in mid‐logarithmic phase and the lowest in the stationary phase with increased number of spherical‐shaped cells. Five neurotoxic components, FjTx‐I, FjTx‐II, FjTx‐IIIa, FjTx‐IIIb and FjTx‐IV, which corresponded to brevetoxin components, PbTx‐1, PbTx‐2, PbTx‐9, PbTx‐3 and oxidized PbTx‐2 were tentatively identified from analysis of F. japonica toxins on TLC and HPLC. The quantity of each component fluctuated with the age and growth stage of the culture. Among the five toxic components the yield of FjTx‐II per cell was highest in both logarithmic and stationary phases.
The Effects of Fry Rearing Density on Hatchery Performance, Fin Condition, and Agonistic Behavior of Rainbow Trout Oncorhynchus mykiss Fry
Authors: Wagner Eric J. , Intelmann Steven S. , Routledge M. Douglas
Published: April 2007

Rainbow trout Oncorhynchus mykiss fry were reared at four densities ranging from 10,800 to 43,926 fish/m3 (9.91 to 37.60 kg/m3) during an initial feeding period of 35 d. Each of the four initial density treatments were then split into high (3,780 fish/m3) and low (1,890 fish/m3) density groups and reared in outdoor raceways for an additional 74 d. A necropsy‐based general health and condition assessment indicated that hematocrit, plasma protein, and the thymus index were significantly elevated in the outdoor high density group. Changes in these variables were unrelated to the initial rearing density, except for plasma protein which decreased as the initial density increased at low densities. Other necropsy variables indicated normal, healthy fish. Agonistic behavior was assessed at 4, 9 and 13 wk of age by observing the number of aggressive chases in paired and group (five fish) trials. The number of chases generally increased with age, although the difference between 9 and 13 wk was variable. Feeding did not elicit more chases in this study except for 9‐wk‐old fry. Initial rearing density did not have any impact on the number of chases at 4 or 13 wk, but at 9 wk the number of chases increased with initial density for the group tests. Relative fin length measurements of all fins except the adipose indicated no combination of initial density and outdoor density was superior to another for reducing fin erosion. This study indicated that rainbow trout fry may be reared at initial densities approaching 44,000 fish/m3 (Piper density index of 1.1) without negatively affecting growth and fin condition or inducing higher levels of agonistic behavior later on.
Use of Microbial Phytase in Channel Catfish Ictalurus punctatus Diets to Improve Utilization of Phytate Phosphorus1
Authors: Jackson L. Scott , Li Meng H. , Robinson Edwin H.
Published: April 2007

A 10‐wk feeding trial was conducted in the laboratory during which channel catfish Ictalurus punctatus (average initial weight: 6.5 g/fish) were fed five practical diets containing either 0, 500, 1,000, 2,000, or 4,000 units of microbial phytase/kg diet. Fish fed diets containing 500 or more units of microbial phytase/kg consumed more feed and gained more weight than fish fed the basal diet without supplemental phytase. Feed conversion ratios (FCR) did not differ among treatments except the FCR for fish fed 1,000 units of microbial phytase/kg diet was lower than that of fish fed no supplemental phytase. Fish survival was not different among treatments. Contrast analysis showed that weight gain, feed consumption, bone ash, and bone phosphorus were higher and feed conversion ratio was lower for fish fed diets supplemented with phytase as compared to fish fed no supplemental phytase. The concentration of fecal phosphorus decreased linearly as phytase supplementation increased. Results from this study demonstrate that microbial phytase is effective in improving bioavailability of phytate phosphorus to channel catfish, which may eventually lead to a reduction in the amount of supplemental phosphorus added to commercial channel catfish feeds.
Refrigerated Storage of Channel Catfish Sperm
Authors: Christensen J. Michael , Tiersch Terrence R.
Published: April 2007

Abstract.— Refrigerated storage of sperm is useful for genetic study and artificial breeding of fishes. Due to the potential loss of donor males, storage is important in species such as channel catfish Icralurus punctatus from which sperm cannot be stripped. This study addresses short‐term storage (at 4 C) of channel catfish sperm by evaluation of storage methods employed for other species and for cryopreservation of channel catfish sperm. The objectives were to evaluate: 1) storage of intact testes and storage of sperm suspended in an extender solution; 2) use of various storage containers with and without supplemental oxygen; 3) use of extender solution with and without the addition of an antibiotic/antimycotic cocktail; 4) use of extender solution with and without the addition of methanol; and 5) use of extender solution with and without the addition of glucose and methanol. Sperm suspended in extender solution retained motility significantly longer (9 d) than did sperm in intact testis (2 d). Sperm stored in Zip‐loc® plastic bags inflated with pure oxygen retained motility significantly longer (12 d) than did sperm stored in Zip‐loc® plastic bags without supplemental oxygen (7 d), or sperm stored in plastic beakers (8 d) or test tubes (8 d) without supplemental oxygen. Sperm stored with the addition of antibiotic/antimycotic cocktail or methanol retained motility significantly longer (10–12 d) than did sperm stored without additives (6–8 d). Sperm stored in extender solution without glucose retained motility significantly longer (19–21 d) than did sperm stored in extender with glucose (13–16 d). Motility was retained for as long as 21 d in sperm stored in extender solution with 5% methanol and without glucose. In each experiment, loss of motility was associated with bacterial growth.
Induced Final Maturation and Spawning of the Marbled Grouper Epinephelus microdon Captured from Spawning Aggregations in the Republic of Palau, Micronesia
Authors: Tamaru Clyde S. , Carlstrom‐Trick Christine , Fitzgerald William J. , Ako Harry
Published: April 2007

A high percentage (98.3%, N= 60) of the marbled grouper Epinephelus microdon individuals captured from spawning aggregations during July and August 1993 in the waters surrounding the island of Koror, Republic of Palau, Micronesia, were in the stage of maturity at which final maturation and spawning could be hormonally induced. The sex ratio of the captured fish was highly skewed towards males (4 male:1 female). Sexually immature females comprised the smallest size class, (<0.6 kg body weight (BW) or 33.0 cm total length (TL)), while sexually mature females were restricted to the 0.6–1.5 kg BW (33.0–46.4 cm TL) groups. Males predominated in size classes >0.6 kg BW, and individuals >1.5 kg BW (46.4 cm TL) were exclusively male. All females with oocytes that averaged (N= 50) >400 μm in diameter were successfully induced to spawn by a two‐injection protocol using human chorionic gonadotropin (HCG) at total dosages of 2,100–3,200 IU/kg fish. All males used in the spawning trials were administered a single injection of HCG at dosages of 500 or 1,000 IU/kg fish. Fecundity ranged between 7.96 × 105−1.24 × 106kg BW, average spawned egg diameters ranged between 769–832 μm, percent fertilization ranged between 32.6%–99.9%, and hatching percentages were >90.0%. Total fat content of eggs obtained from a pooled spawning event was 14.1 mg/100 mg dry weight. The data indicate that HCG is a suitable treatment for the induction of spawning in marbled grouper females that possess a mean oocyte diameter of 400 μm or greater.
Voluntary Spawning of Captive Nassau Groupers Epinephelus striatus in a Concrete Raceway
Authors: Tucker John W. , Woodward Peter N. , Sennett Daniel G.
Published: April 2007

Nassau groupers Epinephelus striatus held in a 37‐m3 concrete raceway were conditioned to spawn 3 mo later than in their home waters. After being held in the raceway for 15 mo, four female and two male groupers spawned voluntarily over a 4‐d period in March 1994, producing 10.3 million eggs. By December 1994, two females had been removed. During March 1995, one of the remaining two females spawned on three consecutive days (60 cm TL, 1,172,000 eggs) and the other only on the third day (47 cm TL, 488,000 eggs). In April 1995, three females (including one held in isolation for 6 mo, then replaced 6 d before the first spawn) produced more than 9.8 million eggs in 4 d. The isolated female spawned 8 d after being placed in a cage in the raceway and 4 d after release in the raceway.

Individual females spawned as many as nine times a day for 1–4 d. Spawning occurred from 3.5 d before until 8.5 d after the full moon. A 30‐d interval elapsed between March and April 1995 spawning periods. Fertilization was in the range 83–100% and hatching 90–100%. Spawns occurred in a temperature range of 23.1–27.9 C; however, based on spawning frequency and volume and on egg development, 24–27 C seems most suitable. These results and other evidence support the view that Nassau groupers can be conditioned to spawn any month of the year, mainly by manipulating temperature.
Effects of Thermal and Thermo‐Haline Shocks on Survival and Osmotic Concentration of the Tilapias Oreochromis mossambicus and Oreochromis aureus × Oreochromis niloticus Hybrids
Authors: Amoudi Mohammad Al , El‐Sayed Abdel‐Fattah M. , El‐Ghobashy Ahmed
Published: April 2007

Abstract.— The effects of thermal and thermo/haline shocks on the tilapias Oreochromis mossambicus and O. aureus × O. niloricus hybrids were investigated. Fingerlings were transferred abruptly from 25 C fresh water to fresh water or salt water (26 ppt) maintaining temperatures of 15, 20, 30 and 35 C. In fresh water, fish survival was not affected by temperature shock, but they suffered from a chill coma and developed fungal infection at 15 C. In salt water, thermo‐haline shock did not affect the survival of O. mossambicus, while the survival rates of tilapia hybrids were 6.7, 100, 100, 70 and 59.7% at 15, 20, 25, 30 and 35 C, respectively. Plasma osmotic concentrations of O. mossambicus transferred to 15 and 35 C salt water were quickly and sharply increased, but gradually decreased to lower levels. Osmotic concentrations of tilapia hybrids were also increased, but never returned to their initial (lower) levels over one week. This study revealed that these fishes are more tolerant to high rather than low temperature shocks and O. mossambicus are more resistant to thermo‐haline shocks rather than tilapia hybrids. It also indicated that thermo‐haline shocks should be minimized during fish transportation and acclimation.
‘Broken‐Skull Disease’ in African CatfishClarias gariepinusis Related to a Dietary Deficiency of Ascorbic Acid
Authors: Eya Jonathan C.
Published: April 2007

Abstract.—Diets containing 0. 23, 46, 69, 92, and 185 mg ascorbic acid/kg of diet were fed to African catfishClarias gariepinusjuveniles (average initial weight, 19.9 g) for 20 wk in glass aquaria. Fish fed diets supplemented with 0 or 23 mg ascorbic acid/kg showed overt signs of broken‐skull disease, such as hemorrhages along the spinal column and inflammation of dorsal skull bone followed by broken skull and death. They also had significantly lower vertebral collagen content and had significantly higher mortality than fish fed 46 mg or more ascorbic acid/kg of diet. Results from this study indicate that a dietary deficiency of ascorbic acid can cause broken‐skull disease and high mortality in African catfish. A concentration of 46 mg ascorbic acid/kg of diet will prevent this anomaly and allow optimum synthesis of vertebral collagen.
Sludge Production and Management for Recirculating Aquacultural Systems
Authors: Chen Shulin , Coffin David E. , Malone Ronald F.
Published: April 2007

Waste discharge from recirculating aquacultural systems is typically in the form of sludge composed of partially stabilized excreta, uneaten food particles, and bacterial growth. The amount of solids produced can be estimated using an equation presented in this paper. In a typical recirculating system, total suspended solids (TSS) is the major pollutant of the sludge produced. The production of TSS ranges from 10 to 30% of the feeding rate on a dry weight basis. The ratio of 5‐d biochemical oxygen demand to total suspended solids (BODS/TSS) of the sludge ranges from 0.10 to 0.2, the total Kjeldahl nitrogen (TKN) content of the TSS ranges from 4 to 6%, and total phosphorus ranges from 0.2 to 2%.

The nature of the waste and the economics of the treatment processes dictate the disposal of aquacultural sludge. Effective clarification of aquacultural waste is critical in reducing sludge volume. Using lagoons for stabilization and storage is the most practical option. While direct disposal by land application seems feasible for rural areas with dry climates, additional stabilization/storage in a lagoon with eventual disposal through land application seems most feasible for a variety of conditions. The effluent produced from the sludge treatment processes can be used for irrigation or for direct discharge after further polishing (treatment).
Diet and Light Intensity Effects on Survival, Growth and Pigmentation of Southern Flounder Paralichthys lethostigma
Authors: Denson Michael R. , Smith Theodore I. J.
Published: April 2007

Interest in the culture of flatfishes has increased globally due to high consumer demand and decreased commercial landings. The Southern flounder Paralichthys lethostigma inhabit South Atlantic and Gulf of Mexico waters and support important commercial and recreational fisheries. In spring, 1996, a two‐part larval rearing study was performed with Southern flounder to examine the effects of three larval diets and two light intensities on survival, growth, and pigmentation. The first part of the study consisted of feeding 6 d post‐hatch (dph) (3.0 ± 0.1 mm TL) larvae three diets: 1) rotifers Brachionus plicatilis at a rate of 10/mL from day 1–9 and Artemia nauplii (3/mL) from day 7 through metamorphosis; 2) rotifers fed day 1 through metamorphosis and Artemia fed day 7 through metamorphosis; or 3) same diet as treatment 1 plus a commercial larval diet added day 13 through metamorphosis. The second part of the study examined the effects of two light levels: low‐light (mean 457 lux) and high‐light (mean 1362 lux). At 24 C, metamorphosis began on day 23 (mean fish size 8.2 ± 0.6 mm TL) in all treatments and was completed by day 30. Analysis of survival, size, and pigmentation data indicated there were no significant differences among feed treatments or between light treatments. Overall survival was 33.4% (±15.9) and mean length was 11.5 mm TL ± 1.3. Only 35% of the larvae were normally pigmented. Reexamination of the pigmentation on day 37 indicated fish reared at the low light intensity through metamorphosis (day 30) but exposed to high light intensity for 1 wk post‐metamorphosis had become significantly more pigmented.
Effects of Replacing Fish Meal with Soybean Meal in Diets for Red Drum Sciaenops ocellatus and Potential for Palatability Enhancement
Authors: McGoogan B. B. , Gatlin D. M.
Published: April 2007

Two 8‐wk feeding trials were conducted with juvenile red drum to determine the maximum levels of soybean meal that may replace fish meal in diets containing 38% crude protein, without reducing weight gain. In the first experiment, fish fed diets containing up to 90% of the protein from soybean meal gained as much weight as fish fed a diet with 100% of protein from fish meal, but fish fed the diet with 100% of its protein from soybean meal gained significantly (P < 0.05) less. Supplementation of glycine and fish solubles individually at 2% (as‐fed basis) in diets containing 90% of their protein from soybean meal tended to increase weight gain of fish compared to those fed a similar diet without supplementation. Similar results were obtained in the second experiment, as fish fed diets containing 90% of their protein from soybean meal gained as much weight as fish fed a diet with 100% of its protein from fish meal. Fish fed diets with 95% and 100% of their protein from soybean meal gained significantly less weight than those fed the diet with all of its protein from fish meal. Supplementation of glycine at 2% in the diet containing 95% of its protein from soybean meal significantly improved weight gain of fish relative to those fed a similar unsupplemented diet. Supplementation of fish solubles at 5% of diet on a dry‐matter basis provided a nonsignificant increase in weight gain compared to that of fish fed a similar unsupplemented diet. In both experiments there was greater observed consumption of the soybean‐meal‐based diets than diets with all of their protein from fish meal. A minimum of 10% of protein from fish meal appears necessary in practical diets containing most of their protein from soybean meal to prevent impaired growth and feed efficiency of red drum.
Microbial Phytase Can Replace Inorganic Phosphorus Supplements in Channel Catfish Ictalurus punctatus Diets1
Authors: Li Meng H. , Robinson Edwin H.
Published: April 2007

Abstract.– Juvenile channel catfish Ictalurus punctatus (initial weight: 6.8 g/fish) were fed four practical diets containing 0, 250, 500, and 750 units of microbial phytase/kg and a diet containing 1% feed grade dicalcium phosphate (but no microbial phytase) under laboratory conditions for 12 wk. Fish fed the diets containing 250 units of microbial phytase/kg and above consumed more feed, gained more weight, and had a lower feed conversion ratio (FCR) in comparison to fish fed the basal diet containing no microbial phytase. Fish fed the diet containing dicalcium phosphate had intermediate weight gain and feed conversion ratio as compared to fish fed the basal diet and diets containing microbial phytase. Bone ash and phosphorus concentrations were lower for fish fed the basal diet than for fish fed other diets. No differences in weight gain, feed consumption, FCR, bone ash and bone phosphorus were observed among fish fed the diets containing various levels of microbial phytase. Fish fed the diet containing dicalcium phosphate had a lower bone phosphorus concentration than fish fed diets containing microbial phytase. Fecal phosphorus concentrations were lower for fish fed the diets containing microbial phytase than for fish fed the basal diet and the diet containing dicalcium phosphate. Results from the present study indicated that addition of 250 units of microbial phytase/kg to practical diets can effectively improve bioavailability of phytate phosphorus to channel catfish and may possibly eliminate the use of an inorganic phosphorus supplement in channel catfish diets. However, these data must be verified in trials conducted in ponds, prior to recommending removal of supplemental phosphorus from channel catfish diets.
Acute Toxicity of 5% Non‐Synergized Emulsifiable Rotenone to White River Crayfish Procambarus acutus acutus and White Perch Morone americana
Authors: Wujtewicz Donald , Petrosky Bernard R. , Petrosky Dorene L.
Published: April 2007

Annual drawdown of crayfish culture ponds to plant forage crops also serves to eradicate most predaceous finfish. Without annual drawdown predaceous fish populations may reach numbers that can significantly reduce the crayfish crop. Frequent drawdown may not be feasible or desirable in some management schemes. Evidence in the literature suggests that differential toxicity of rotenone would allow removal of fish without harming crayfish in the same pond. In the current study, laboratory and in situ acute toxicity bioassays (96 h) were conducted with 5% non‐synergized emulsifiable rotenone to define the maximum non‐lethal concentration (LC100) for white river crayfish Procambarus acutus acutus and the minimum lethal concentration (LC100) for white perch Morone americana. Six concentration levels of rotenone formulation were tested in each of six toxicity trials with crayfish using dechlorinated tap water at 21–25 C. LC0 (compensated for control mortality) was determined to be 3.0 mg/L. Significant crayfish mortality began at 4.0 mg/L. Acute toxicity to white perch was anticipated to be within recommended concentration levels on product label for similar fish, and was corroborated by laboratory bioassay (LC100 of 0.15 mg/L). Both species were then tested together in laboratory aquaria utilizing pond water at room temperature. Concentration levels of 0.05–2.5 mg/L killed all white perch with no crayfish mortality. In the final phase of the study a 1.0 mg/L concentration of rotenone was applied to a pond containing both species held in cages. All white perch were dead within 24 h; no crayfish mortality was observed for the 96‐h duration of the trial. It may therefore be possible to use this rotenone formulation to control white perch and other finfish in active crayfish culture ponds.
Reproductive Performance of Different Sized Wild and Pond‐reared Penaeus paulensis Females
Authors: Cavalli Ronaldo O. , Scardua Marcos P. , Wasielesky Wilson
Published: April 2007

The present study analyzes the reproductive performance of three size classes of wild (average weight of 46.5, 55.0, and 63.2 g) and three size classes of pond‐reared (18.4, 21.3, and 25.1 g) Penaeus paulensis females. Unilaterally eyestalk ablated females were placed for 70 d in 3.6 m diameter tanks at 6 individuals/m2 and a 1.2:1 female‐male ratio. Number of spawns, eggs, nauplii, fertilization and hatching rates were recorded every second day. The length of unfed protozoea I larvae was also recorded. Larger broodstock shrimp tended to suffer higher mortality rates. Smaller, pond‐reared females started spawning at 28.2 ± 4.1 g. The number of eggs and nauplii per spawning event were not significantly different between experimental groups (P > 0.05), but due to their higher spawning frequency, small wild females (46.5 ± 3.7 g) outperformed medium (55.0 ± 1.8 g) and large ones (63.2 ± 7.0 g). No relationship between protozoea length and spawner size was found. Optimum size for the maturation of wild P. paulensis females was estimated to be from 30 to 60 g. It is suggested that the use of this size range can potentially enhance nauplii production of P. paulensis.
Fry Production of Shire River Tilapia Oreochromis shiranus at Two Broodstock Sex Ratios1
Authors: M'Hango Tony , Brummett Randall E.
Published: April 2007

Abstract.— Shire River tilapia Oreochromis shiranus broodfish were stocked at a density of 1.25 fish/m2 and sex ratios of either 1:1 or 1:3 (males: females). Two weeks after stocking, fry collection began. Fry were then harvested weekly for 9 wk with a fine‐meshed dip net operated from the pond bank for 1.5 h each morning and afternoon. Ten weeks after fry collection began, all ponds were drained and completely harvested. Over the entire 84 d, fry production averaged 0.78 fry/m2 per d and did not differ (P < 0.05) between treatments. Fry production per female was significantly higher (P < 0.02) in ponds stocked at a 1:1 sex ratio (111 fry/female) compared to a 1:3 sex ratio (66 fry/female). To avoid inbreeding without sacrificing production, a broodstock sex ratio of 1:1 can safely be used when producing O. shiranus fry at a density of 1.25 fsh/m2 in earthen ponds. Competition among females is a possible cause of reduced fry production in densely‐stocked brood ponds.
Tolerance of Juvenile Flatfish Paralichthys orbignyanus to Acid Stress
Authors: Wasielesky Wilson , Bianchini Adalto , Santos Marcos H. S. , Poersch Luis H.
Published: April 2007

Abstract.— The tolerance of juvenile flatfish Paralichthys orbignyanus to acid stress, was studied in 30‐L plastic tanks using ten flatfishes (95 ± 13 g) per treatment. Water pH was monitored every 3 h and re‐adjusted to the test pH using either HCl or NaOH. The photoperiod was fixed at 12L:12D, water temperature at 23 ± 0.8 C, and salinity at 30 ppt. Fish survival and ventilatory rate were monitored daily. At pH 4.0, we observed 100% mortality and ventilation rates different from controls. At pH 5.2, there was 100% survival even after 96 h. However, ventilation rate was higher than in controls. At pH equal or higher than 6.0, we observed 100% survival and normal ventilation rates. The estimated pH which would kill 50% of test organisms were: 4.51, 4.50 and 4.40 after 48, 72, and 96 h of experiment, respectively. These results show that juvenile flatfish are relatively tolerant to acid stress.
Effect of Dietary Vitamin C on Weight Gain, Tissue Ascorbate Concentration, Stress Response, and Disease Resistance of Channel Catfish Ictalurus punctatus1
Authors: Li Meng H. , Wise David J. , Robinson Edwin H.
Published: April 2007

Juvenile channel catfish Ictalurus punctatus (average initial weight, 6.5 g/fish) were fed twice daily to apparent satiation with practical‐type diets containing 0, 50, 150, or 250 mg supplemental vitamin C/kg from L‐ascorbyl‐2‐polyphosphate for 10 wk under laboratory conditions. At the end of the feeding period, one half of the fish were stressed for 2 h by confinement and both stressed and nonstressed fish were exposed to a virulent strain of Edwardsiella ictaluri. Weight gain and feed conversion efficiency were lower for fish fed the basal diet than those fed diets containing supplemental vitamin C. No differences were observed in weight gain and feed conversion among fish fed diets containing supplemental vitamin C. There were no differences in feed consumption and survival (prior to experimental infection) among treatments. No vitamin C deficiency signs except reduced weight gain were observed in fish fed the basal diet. Serum cortisol concentrations were higher in stressed fish than in non‐stressed fish. Dietary vitamin C level had no effect on serum cortisol concentration. As dietary vitamin C increased, ascorbate concentration in serum and liver increased. Confinement stress had no effect on serum and liver ascorbate concentrations. Cumulative mortality of channel catfish 21 d subsequent to experimental infection with E. ictaluri was higher for stressed fish than for nonstressed fish. Regardless of stress or nonstress, overall mortality for fish fed the basal diet was lower than the fish fed diets containing supplemental vitamin C. There were no differences in post‐infection antibody levels among treatments or between stressed and nonstressed fish. Results from this study indicate that channel catfish require no more than 50 mg/kg dietary vitamin C for normal growth, stress response, and disease resistance.