bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecology of Blue‐Green Algae in Aquaculture Ponds
Authors: Paerl Hans W. , Tucker Craig S.
Published: April 2007

Cyanobacteria (blue‐green algae) in the genera Anabaena, Aphanizomenon, Microcystis, and Oscillatoria often form extensive and persistent blooms in freshwater aquaculture ponds. Bloom‐forming cyanobacteria are undesirable in aquaculture ponds because: 1) they are a relatively poor base for aquatic food chains; 2) they are poor oxygenators of the water and have undesirable growth habits; 3) some species produce odorous metabolites that impart undesirable flavors to the cultured animal; and 4) some species may produce compounds that are toxic to aquatic animals. Development of cyanobacterial blooms is favored under conditions of high nutrient loading rates (particularly if the availability of nitrogen is limited relative to phosphorus), low rates of vertical mixing, and warm water temperatures. Under those conditions, dominance of phytoplankton communities by cyanobacteria is the result of certain unique physiological attributes (in particular, N2 fixation and buoyancy regulation) that allow cyanobacteria to compete effectively with other phytoplankton. The ability to fix N2 provides a competitive advantage under severe nitrogen limitation because it allows certain cyanobacterial species to make use of a source of nitrogen unavailable to other phytoplankton. The ability to regulate cell buoyancy through environmentally‐controlled collapse ad reformation of intracellular gas vacuoles is perhaps the primary reason for the frequent dominance of aquaculture pond phytoplankton communities by cyanobacteria. Cyanobacteria that can regulate their position in the water column gain a distinct advantage over other phototrophs in poorly mixed bodies of water. In addition to the physicochemical interactions that influence phytoplankton community dynamics, cyanobacterial‐microbial associations may play an important regulatory role in determining community structure. Cyanobacteria are always found in close association with a diverse array of microorganisms, including eubacteria, fungi, and protozoans. These associations, which in the past have often been viewed as antagonistic, are increasingly seen as mutualistic and may function in a positive manner during bloom development.
Significance of Fish Size‐At‐Release on Enhancement of Striped Mullet Fisheries in Hawaii
Authors: Leber Kenneth M.
Published: April 2007

A tag‐release‐recapture study was conducted to evaluate size‐at‐release impacts upon recruitment of cultured, juvenile striped mullet, Mugil cepahlus released in inshore habitats of Oahu, Hawaii, USA. In June and July 1990, 85,848 juvenile mullet were graded into five size groups (ranging from 45 to 120 mm in length), identified with binary‐coded wire tags, and released into two estuaries (2×5 factorial design). Of the tagged fish, 42,822 were released into Kaneohe Bay on the east (windward) coast of Oahu; 43,026 were released into Maunalua Bay on Oahu's dryer south shore. The fish were released into both bays simultaneously. Releases were blocked in time across 5 release lots. To evaluate growth and survival rates of released mullet, both bay systems were sampled monthly with cast nets over a ten‐month period after release. Overall, 733 tagged M. cephalus were recaptured, 277 from Kaneohe Bay and 456 from Maunalua Bay. Overall proportions of tagged fish in samples declined from 33.4% (±25.2%) of the total M. cephalus catch at week 5 to 1.88% (±0.95%) by week 23. From week 23 on, tagged fish averaged 2.09% (±0.23%) of the striped mullet in monthly samples. Within 9 wk after releases, recapture frequencies were clearly skewed in favor of fish that were larger at the time of release. Fish smaller than 70 mm when released were rare or absent in collections within 18 wk after release. This confirms results of a smaller‐scale pilot study in Maunalua Bay and shows that fish size‐at‐release can have a major impact on the success of hatchery releases in marine habitats. Pilot studies to identify minimum fish size‐at‐release should be conducted at all sites targeted for full‐scale marine hatchery releases.
Increased Densities Result in Reduced Weight Gain of Crayfish Orconectes virilis1
Authors: Brown Paul B. , Wilson Keith A. , Wetzel James E. , Hoene Benjamin
Published: April 2007

Three independent studies were conducted in which supplemental food was provided to juvenile Orconectes virilis reared at varying densities. One study was conducted in fiberglass tanks (densities of either 13, 27 or 54 individuals/m2) and two were conducted in outdoor pools (densities of either 2.5, 5, 10, 20 or 30 individuals/m2). Crayfish were offered a variety of foods ranging from a formulated diet to agricultural forages. Weight gain of crayfish fed a formulated diet and reared at varying densities was similar in the study conducted in tanks, but survival was significantly lower at the two highest densities (27 and 54/m2). Weight gain, survival and yield decreased as density increased in the studies conducted in outdoor pools. The highest weight gain and survival were at a density of 2.5/m2. Wheat straw was used as the source of nutrients. Use of formulated diets did not result in rapid weight gain when crayfish were reared at higher densities.
Maturation and Reproduction of Pond‐Reared Penaeus schmitti
Authors: Ramos Laida , Espejo Manuel , Samada Soraya , Pérez Lourdes
Published: April 2007

Penueus schmitti broodstock was grown from postlarvae in a three‐stage semi‐intensive pond system. Mean weight after 10.5 mo was 51.2 g for females and 33.8 g for mnles. Reproductive response was evaluated in two studies. The first study was conducted with unilaterally ablated or unablated females and males with ejaculated or non‐ejaculated spermntophores. The best response was achieved with ablated females and with non‐ejaculated males (0.87 spawas/maturation tank per d and 22.254 nauplii/maturation tank per d). The second study compared the reproductive response of captive ablated females mated with pond‐reared males or wild males. More nauplii were produced from wild males (78,583 nauplii/maturation tank per d) than from pond‐reared males (57,777 nnuplii/tank per d). The reproductive culture cycle of P. schmitti has been closed for the first time in Cuba on a commercial scale with the collection and stocking of postlarvae of the F1 generation.
The Annual Reproductive Cycle of the White BassMorone chrysops
Authors: Berlinsky David L. , Jackson Leslie F. , Smith Theodore I. J. , Sullivan Craig V.
Published: April 2007

The gametogenic cycle of the white bassMoronc chrysopswas characterized for one year at monthly intervals by measuring circulating levels of the sex steroid hormones testosterone (T) and 11‐ketotestosterone (11‐KT) in males, and 17β‐estradiol (E2) and T in females. Vitellogenin (VTG), the egg yolk precursor, was also measured in female blood plasma. Gonadal status of individual fish was assessed by histological evaluation, measurement of oocyte diameters, and spermintion response. At the onset of vitellogenesis (October), blood plasma levels of E2and T were low, but increased significantly as the spawning period (March‐April) approached and oocytes attnined their maximum diameter. All stages of oocyte development were observed in mature females, indicating that the white bass is a multiple‐clutch, groupsynchronous spawner. Androgen levels increased in males throughout the reproductive cycle and reached maximal levels during the spawning period. The increase in androgens coincided with sperm production and spermintion in males. The circannual endocrine and gonadal development patterns observed in white bass were similartothose of other members of genusMoronc.
The Effect of Live and Artificial Diets on Growth, Survival, and Trypsin Activity in Larvae of Penaeus indicus
Authors: Kumlu Metin , Jones D. A.
Published: April 2007

In this study, partial and total replacement of live diets (microalgae and Artemia nauplii) with microencapsulated diets (MED) are demonstrated for larval culture of P. indicus. Slower growth and lower survival rate of larvae fed experimental MED were significantly improved by a supplement of 15 cells/μL frozen mixed algae (1:2, Tetrtaselmis and Skeletonema) during protod stages (PZ1–PZ3). This low level of algal supplement to MED resulted in survival (85–92%) equal to that obtained from control live diets (91%) during protod stages. These significant improvements in larval growth and survival are likely to be due to higher larval digestive enzyme activities and hence more efficient digestion of the artificial diet by the larvae. Like other penaeids, P. indicus larvae show high total and tissue trypsin activities during PZ stages, with a peak at mysis stage 1 (M1), and a decrease during subsequent stages when fed on conventional live diets of algae followed by Artemia during mysis stages. Larvae fed 15 ceUs/μL mixed frozen algae in addition to MED demonstrated a significantly higher trypsin activity throughout herbivorous larval stages in comparison to larvae fed solely on MED. A freeze dried alga Rhinomonas reticulata incorporated into a MED at 23Vo (v/v) induced larval trypsin activity equal to that produced by live algae. Hence, the algal substances, which trigger digestive enzyme production, may be retained within the microcapsules. At mysis stages, however, addition of live prey (one Artemia/mL) to cultures fed with MED significantly improved growth and survival although it depressed trypsin activity. For mysis stages it appears that the use of predigested ingredients is necessary to improve the digestibility of formulated diets.
Maximizing First‐Year Growth of Mixed‐Sex Blue Tilapia Oreochromis aureus in Polyculture with Catfish Ictalurus spp.
Authors: Morrison John R. , Deavours William L. , Jones J. C. , Tabb Mark A.
Published: April 2007

Mixed‐sex blue tilapia Oreochromis aureus fry were produced from indoor spawns in March and April. Fry were stocked in May at an average weight of 0.5 g at 0, 250, 750, or 2,500/ha into ponds which had been stocked previously with three catfish strains at a combined density of 10,000 fingerlings/ha. After a 167‐d culture period, from 15 May until 4 November, tilapia stocked at 250 or 750/ha grew to average harvest size approaching 0.45 kg. No significant difference in average size was observed between males and females except at the 2,500 tilapia/ha stocking density. Sixty percent of the tilapia polyculture ponds yielded no reproduction at harvest and maximum reproduction observed was 13.5 kg/ha. Lack of reproduction and the undeveloped state of sampled female ovaries indicated that most females had yet to attain sexual maturity. Catfish production and catfish feed conversion was not significantly different between tilapia polyculture and catfish monoculture ponds (P > 0.05). First seine hauls yielded over 88% of the total catfish harvest, but only an average of 3.9% of the marketable tilapia. Tilapia had no measurable impact on the incidence of catfish off‐flavor at any of three sample intervals. Overall average levels of TAN and nitrites did not differ significantly between treatments; however, mean chlorophyll a concentration was significantly higher (P > 0.05) in the 2,500 tilapia/ha treatment than at lower tilapia densities.
Gynogen Production in Hybrid Striped Bass
Authors: Leclerc Gilles M. , Ely Bert , Xu Xiao Lan , Harrell Reginal M.
Published: April 2007

Abstract.— Meiotic gynogens were produced using hybrid striped bass (♀ white bass, Morone chrysops, ×♂ striped bass, M. saxatilis) eggs and white perch M. americana UV‐irradiated sperm. Diploidy of the fertilized eggs was restored by application of hydrostatic pressure, which induced retention of the second polar body. Use of white perch sperm provided an unmistakable marker for detection of a paternal genetic contribution. Two assays were developed using the polymerase chain reaction (PCR) to amplify specific regions of the Morone genome. Primers for gene amplification were developed based on the DNA sequence of the striped bass growth hormone gene (SB‐GH) or an anonymous striped bass locus (SBI‐10). Control experiments using DNA from the three Morone species demonstrated that gene amplification yielded species‐specific patterns of DNA fragments for both of these loci. Therefore, any progeny with a paternal contribution of a set of white perch chromosomes could be identified. Using these assays, we demonstrated that greater than 75% of the progeny obtained from successful experiments were true gynogens. These striped bass hybrid gynogens will provide the basis for future efforts to calculate gene‐centromere distances and to identify markers linked to specific traits of interest to aquaculture.
Nutritional Enhancement of n‐3 and n‐6 Fatty Acids in Rotifers and Artemia Nauplii by Feeding Spray‐dried Schizochytrium sp.
Authors: Barclay William , Zeller Sam
Published: April 2007

A docosahexaenoic acid (DHA), 22:6(n‐3), rich strain of Schizochytrium sp. was used in a spray‐dried form to evaluate the enhancement of highly unsaturated fatty acids (HUFAs) in Artemia franciscana nauplii (Utah biotype) and the rotifer Brachionus plicatilis. This heterotrophic microalga was selected because of its high concentration of the longest chain HUFAs in the n‐3 and n‐6 series, DHA and docosapentaenoic acid (DPA), 22:5(n‐6), respectively. When 24‐h‐old Artemia nauplii were fed 400 mg/L of the algae for 24 h, the DHA content of the nauplii went from undetectable levels to 0.8% of dry weight and the omega‐3 HUFA eicosapentaenoic acid (EPA), 20:5n‐3, content went from 0.1% to 0.5% of dry weight in the nauplii. Similarly, 22:5(n‐6) increased in the nauplii from undetectable levels to 0.4% of dry weight, with a concomitant increase in arachidonic acid, (20:4n‐6), from trace to 0.3% of dry weight even though there was no arachidonic acid in the algal biomass. Similar enrichment patterns were observed in rotifers. The results suggest that spray‐dried cells of Schizochytrium sp. are effective in enriching Artemia naupli and rotifers in both n‐3 and n‐6 HUFAs. The results also suggest that Artemia nauplii and rotifers are capable of readily retroconverting 22:6(n‐3) to 20:5(n‐3) and 22:5(n‐6) to 20:4(n‐6) through the process of β‐oxidation, a well‐known process in mammals.
Growth Response of Nile Tilapia Oreochromis niloticus to Dietary L‐Ascorbic Acid, L‐Ascorbyl‐2‐Sulfate, and L‐Ascorbyl‐2‐Polyphosphate
Authors: Abdelghany Ali E.
Published: April 2007

Abstract.— Purified diets were formulated and fed to seven groups of Nile tilapia Oreochromis niloricus fingerlings for 12 weeks. Six of the formulated diets contained 5 or 50 mg/kg of ascorbic acid equivalent supplied either by L‐ascorbic acid (AA), L‐ascorbyl‐2‐sulfate (AS) or L‐ascorbyl‐2‐polyphosphate (APP). The seventh basal diet was ascorbate‐free and served as the control. The study indicated that APP or AS was more effectively utilized as a source of vitamin C than equimolar AA in promoting growth, improving food conversion, and preventing scurvy in Nile tilapia. Fish fed the ascorbate‐free diet and the diet containing 5 mg AA/kg exhibited external signs of scurvy at 10 weeks. Diets containing 5 mg/kg of ascorbic acid from AS or APP provided some growth with no overt signs of scurvy indicating that this concentration of AS and APP might be near the minimum requirements for the species. The best growth, food conversion ratio, survival rate, and ascorbic acid content in liver were obtained with the diet containing 50 mg ascorbate equivalent/kg diet from APP followed by the diet containing 50 mg ascorbate equivalent/kg diet from AS. Fish fed diets with 50 mg ascorbic acidkg diet from AS and APP gained 27.9% and 36.2% more weight, respectively, than fish fed diets with 50 mg ascorbic acidkg diet from AA. These results indicated nearly equal ascorbic acid activity from AS and APP.
Continuous Monitoring of Dissolved Oxygen and Total Dissolved Gas Pressure Based on Head‐Space Partial Pressures
Authors: Watten Barnaby J. , Smith David R. , Ridge William J.
Published: April 2007

We describe an instrument prototype that measures total dissolved gas pressure (TGP) and dissolved oxygen (DO) without need for standard wetted probe membranes or gas permeable tubing. Measurements were based instead on gas‐phase partial pressures that develop within the head‐space of a pressure vessel, and on Henry's Law. Performance trials established that differences between standard instrumentation and test instrument OP readings average ‐1.6‐mm Hg (SD = 2.19, range ‐4.8 to ‐5.3) within the ΔP range of ‐72 to 123‐mm Hg. Additional trials demonstrated the ability of the instrument to closely follow positive and negative changes in TGP at rates approaching 30‐mm Hg/h. Here, the difference between test and standard instrumentation derived TGP averaged 3.4‐mm Hg (range 0–41). Differences in ΔP measured by test instrument and gasometer increased with water throughput; mean differences were ‐3.9, ‐4.3, and ‐6.0 for water throughput of 4.6, 6.7, and 7.8 L/min, respectively. However, time to reach 90% of the steady‐state instrument reading was highest for low water throughput; equilibrium times averaged 90.9, 44.4, and 44.7 min for water throughput of 4.6, 6.7, 7.8 L/min, respectively. Differences between titration and test‐instrumentation based DO measurements were acceptable, averaging ‐0.11 mg/L (SD = 0.41, range ‐0.85 to 0.85) over DO from 3.3 to 19.2 mg/L and for 11.1 and 24.2 C. Whereas test instrument DO readings were indistinguishable from Winkler titration at 24.2 C; at 11.1 C there was a tendency for test instrument readings to be lower than Winkler titration at DO < 14 mg/L and higher at DO > 14 mg/L. Trials conducted under biological fouling conditions demonstrated the test instrument's ability to operate with 30% of the maintenance required by standard instrumentation.
Growth and Body Composition of Juvenile Hybrid Bluegill Lepomis cyanellus × L. macrochirus Fed Practical Diets Containing Various Percentages of Protein
Authors: Webster Carl D. , Tiu Laura G. , Tidwell James H.
Published: April 2007

Growth, survival, and body composition were evaluated in two feeding trials using juvenile hybrid bluegill Lepomis cyanellus×L. macrochirus. In Experiment 1, hybrid bluegill (20 g) were stocked into 1.25‐m3 cages at a rate of 300 fish/cage and fed diets containing 35, 40, 44, or 48% protein for 12 wk. Fish meal comprised 32% of the dietary protein in all diets. Fish were fed all they could consume in 40 min. No significant differences (P > 0.05) in individual length, individual weight, specific growth rate (SGR), condition factor (K), and feed conversion ratio (FCR) were found among treatments and averaged 13.4 cm, 47.4 g, 1.02%/d, 1.96, and 4.06, respectively. Whole‐body composition of hybrid bluegill indicated that fish fed a diet containing 35% protein had a significantly lower (P < 0.05) percentage protein (56.3%) and a higher (P < 0.05) percentage lipid (29.3%) compared to fish fed diets containing 40, 44, and 48% protein. In Experiment 2, 15 hybrid bluegill (15 g) were stocked into 110‐L aquaria and fed one of four diets containing 28, 32, 36, or 38% protein for 10 wk. Fish were fed twice daily all they would consume in 20 min. Fish fed a diet containing 38% protein had higher (P < 0.05) percentage weight gain (265%) than fish fed diets containing 28% (203%) and 32% (219%) protein, but were not significantly different (P > 0.05) compared to fish fed a diet containing 36% protein (251%). Feed conversion ratio (FCR) of hybrid bluegill fed diets containing 36% and 38% protein (average 1.39) were significantly lower (P < 0.05) than fish fed a diet with 28% protein (1.73). Results from these studies indicate that hybrid bluegill can be fed a practical diet containing 35–36% protein (with fish meal comprising 32% of the protein). Further refinement of the diet formulation may allow producers to reduce diet and production costs.
Multi‐Locus DNA Fingerprinting of Channel Catfish Ictalurus punctatus
Authors: Bosworth Brian G. , Wolters William R.
Published: April 2007

Abstract.— Similarities among multi‐locus DNA fingerprints of five channel catfish Ictalurus punctatus strains and the ability to identify the strain of a fish based on its fingerprint pattern were investigated. Five restriction enzymes and 13 multi‐locus DNA probes were screened to identify enzyme‐probe combination useful for DNA fingerprinting channel catfish. Restriction enzymes Hinf I and Dpn II, in combination with probes (CAC)n, (CGC)n, (CTC)n, (ATCC)n, and (GATA)n, produced useful fingerprints (20–30 resolvable bands for each enzyme‐probe combination). Thirty individuals (3 pools of 10 individuals each) from each of five channel catfish strains (albino, Mississippi normal, USDA‐102, USDA‐102 select, and USDA‐103) were fingerprinted with all useful enzyme‐probe combinations. Band sharing among samples was higher within strains than among strains and band sharing among strains was higher for strains whose breeding history indicated a high degree of relatedness. Individual fingerprints of 18 fish from each of the USDA‐102 select and USDA‐103 strains revealed no strain‐specific bands, but several diagnostic bands (present at high frequencies in either USDA‐102 select or USDA‐103 strains and at a low frequencies in other strains) were identified. Band sharing at diagnostic bands was used to correctly identify fish as USDA‐102 select or USDA‐103 strains with 82% accuracy from fingerprints of 17 USDA‐102 select strain fish, 18 USDA‐103 strain fish, and 38 fish collected from three commercial farms.
Water Quality in Laboratory Soil‐Water Microcosms with Soils from Different Areas of Thailand
Authors: Boyd Claude E. , Munsiri Prasert
Published: April 2007

Forty‐five soil samples were collected from aquaculture areas in 23 provinces of Thailand to include six soil orders and wide variation in physical and chemical properties. Soil‐water microcosms were prepared containing 5 g of soil and 150 mL of distilled water. Microcosms were held on an oscillating table shaker (150 rpm) for 1 wk at 25 C in the dark. Water pH and concentrations of dissolved nutrients, total alkalinity, and total hardness were measured. Differences in properties within soil orders caused wide variation in composition of solutions and differences in concentrations of dissolved substances and pH were not related to soil order. Regression analyses revealed significant correlations between concentrations of soil nutrients extractable in dilute acid (0.05 N HCI plus O.025 N H2SO4) or in neutral, 1 N ammonium acetate and aqueous concentrations. Regression coefficients usually were higher for dilute‐acid extractable nutrients than for ammonium acetate extractable ones. Regression coeficients based on dilute‐acid extractable nutrients follow: soluble reactive phosphorus (r= 0.816); calcium (r= 0.685); magnesium (r= 0.470); potassium (r= 0.959); sodium (r= 0.977); manganese (r= 0.462); boron (r= 0.399). The correlation between soil and solution iron was not significant and aqueous concentrations of copper and zinc were below detection limit. Hardness was correlated with soil carbon (r= 0.710) and soil pH was a good predictor of alkalinity (r= 0.877). Soil pH and aqueous pH were highly correlated (r = 0.939). Findings suggest that soil characteristics can be used to predict pH and concentrations of several dissolved substances in soil‐water systems under aerobic conditions.
Solubility of Selected Inorganic Fertilizers in Brackish Water
Authors: Teichert‐Coddington David , Boyd Claude , de Pinel Delia Martinez
Published: April 2007

Abstract.— Diammonium phosphate, monoammonium phosphate, triple superphosphate, and urea were dropped through a 1‐m column of water which ranged from 0 to 40 ppt salinity. Mean solubility of nitrogen was 4.1% from diammonium phosphate, 11.8% from monoammonium phosphate, and 76.8% from urea. Mean solubility of phosphorus was 4.6% from diammonium phosphate, 10.4% from monoammonium phosphate and 4.4% from triple superphosphate. Salinity did not significantly affect the solubility of nitrogen and phosphorus from diammonium phosphate. Nitrogen solubility from monoammonium phosphate and phosphorus solubility from triple superphosphate significantly decreased with increasing salinity, but the correlations were low. Urea solubility, and phosphorus solubility from monoammonium phosphate responded curvalinearly to increasing salinity. Solubility differences caused by salinity disappeared after 24 h of contact with water when all fertilizers dissolved completely regardless of salinity. No adjustment for salinity is necessary when fertilizer rates are calculated for brackish water or marine application.
Uptake and Clearance of Edwardsiella ictaluri in the Peripheral Blood of Channel Catfish Ictalurus punctatus Fingerlings during Immersion Challenge
Authors: Wise David J. , Schwedler Thomas E. , Terhune Jeffery S.
Published: April 2007

Uptake and clearance of Edwardsiella ictaluri in the peripheral blood of channel catfish Ictalurus punctatus fingerlings were monitored for 216 h after exposure to E. ictaluri for 4 h and 8 h under static conditions. Most fish exposed to E. ictaluri developed bacteriemia 24 h post‐exposure, and by 72 h post‐exposure E. ictaluri was recovered from all the blood of all exposed fish. The number of E. ictaluri colony forming units (CFU) in the blood of moribund fish ranged between 1.7 × 103 to 1.6 × 105 CFU/50 μL whole blood. Clearance of bacteria from the blood was observed by 216 h post‐exposure and all fish surviving bacterial exposure developed agglutinating antibody against E. ictaluri. The pathogenesis of the infection was accompanied by the shedding of viable E. ictaluri into the water which may serve as a mechanism by which fish to fish transmission occurs.
Protein and Energy Levels for Maximum Growth, Diet Utilization, Yield of Edible Flesh and Protein Sparing of Hybrid Clarias Catfish (Clarias macrocephalus×Clarias gariepinus)
Authors: Jantrarotai Wimol , Sitasit Prasert , Jantrarotai Pattanee , Viputhanumas Thavee , Srabua Pranee
Published: April 2007

Abstract— Two feeding trials were performed to determine dietary protein and energy levels for maximum growth, diet utilization, yield of edible flesh and protein sparing of hybrid Clarias catfish (Clanas macrocephalus × Clarias gariepinus). A 3 × 3 factorial design was employed for experiment 1 in which nine diets containing either 20, 30 or 40% protein and 275, 300 or 325‐kcal digestible energy/100 g were used. The follow‐up experiment 2 was a 3 × 2 factorial in which three protein levels (30, 35 and 40%) and two digestible energy levels (275 and 325 kcal/100 g) were tested. Dietary ingredients used in both studies were similar but the ratios of energy provided by dextrin and lard were 11.3/1.0 and 3.8/1.0 for experiments 1 and 2, respectively. Each of the experimental diets was fed to apparent satiation twice daily to three aquaria of fish (15 fish/aquaria) with average weight of 4.0 and 2.0 g for experiment 1 and 2, respectively, for 8 wk. Performance of fish in experiment 1 was mainly influenced by dietary protein rather than by energy levels. Maximum growth and diet utilization were attained at dietary protein and energy levels of 40% and 275 kcal/100 g, respectively. Energy levels did not spare dietary protein in experiment 1. In experiment 2, growth, diet utilization, and yield of edible flesh of fish were influenced by protein and energy levels. Furthermore, the protein sparing effect was observed in experiment 2. Best performance and protein sparing were found at 35% protein and 325‐kcal digestible energy/100 g. The studies showed that dietary protein and energy requirement for hybrid Clarias catfish are affected by carbohydrate to lipid ratio. Fish utilize dietary energy with a dextrin to lard ratio of 3.8/1.0 more efficiently than that with a ratio of 11.3/1.0. Therefore, dietary protein and energy for best performance and protein sparing of hybrid Clarias catfish reported for experiment 2 were more appropriate.
The Effects of Different Types of Stress on Blood Glucose in the Giant Tiger Prawn Penaeus monodon
Authors: Hall M. R. , van Ham E. H.
Published: April 2007

Abstract— Juvenile Penaeus monodon prawns were exposed to a variety of putative stressom and blood glucose concentrations monitored as an index of metabolic stress. Prawns were held under controlled conditions and food deprived for 12–18 h before blood sampling. Juvenile prawns maintained in tanks at densities of 9, 23, 36 and 50 prawns/m2 for 4 wk did not have significantly different baseline levels of blood glucose, with mean concentrations varying from 1.1 to 1.3 mmol/L. In contrast, as an index of overall condition, antennal length and rostral spine length were significantly degraded in the 36 and 50 prawns/m2 groups compared to the 9 and 23 prawns/m2 groups (P < 0.05). Blood glucose levels were significantly elevated after prawns were exposed to air for 10 min and also increased Significantly when dissolved oxygen was decreased from 6.5 mg/L to 2.1 mg/L. (P < 0.05). Gassing of water from pH 8.5 to 5.9 with carbon dioxide, with a corresponding decrease of dissolved oxygen from 6.6 to 5.9 mg/ L, induced a rapid and significant rise in blood glucose levels from 1.1 to 2.3 mmol/L. In contrast, a decrease of water pH from 8.3 to 5.9 with sulfuric acid, did not result in a significant change in blood glucose concentrations. These findings are discussed in relation to pond management for maintaining prawns in a low stress environment.
The Effects of Prophylactic Formalin Bath Treatment on Blood Glucose in the Giant Tiger PrawnPenaeus monodon
Authors: van Ham E. H. , Hall M. R.
Published: April 2007

Abstract—JuvenilePenaeus monodonprawns were bathed in seawater‐formaldehyde concentrations of 312, 625, and 1,250 ppm for up to 6 h. The tests were conducted at concentrations in excess of those previously published, in order to examine maximum tolerance levels to formaldehyde. Physiological stress was monitored by measurement of blood glucose levels. Under controlled laboratory conditions, 12 h food deprived juvenile prawns exposed to formaldehyde concentrations of 312 ppm did not exhibit signs of stress. However, bathing in formaldehyde concentrations of 625 and 1,250 ppm, caused significant increases (P< 0.05) in blood glucose levels after 2 and 4 h, respectively. There were no mortalities in any treatment group. In contrast, juvenile prawns from grow‐out ponds bathed in 625 ppm of formaldehyde immediately after 2.5 h of transport did not exhibit significant increases in blood glucose. This may be due to their nutritional status and these results are discussed. No significant change in blood glucose levels was observed in bilaterally eyestalk ablated prawns after exposure to 1,250 ppm formaldehyde. The increase of blood glucose due to formaldehyde treatment is presumably mediated by a stress response, which includes crustacean hyperglycemic hormone (CHH), and not a result of non‐specific cell lysis and death.
Hormone Profiles of Captive Striped Bass Morone saxatilis During Spermiation, and Long‐Term Enhancement of Milt Production
Authors: Mylonas Constantinos C. , Zohar Yonathan , Woods L. Curry , Thomas Peter , Schulz Rüdiger W.
Published: April 2007

Abstract— Plasma profiles of reproductive and thyroid hormones were studied in captive striped bass Morone saxatilis during an 11‐wk period encompassing the spawning season, and the effect of a sustained‐release gonadotropin‐releasing hormone agonist (GnRHa)‐delivery system (GnRHa‐implant) on milt production was evaluated. The highest percentage of spermiating fish was observed between mid‐April and mid‐May, and mean total expressible milt ranged from 3.5 to 6.0 mL/kg. Plasma gonadotropin II (GtH II) increased significantly, though inconsistently, during the spermiation period, whereas testosterone and 11‐ketotestosterone levels declined continually. Plasma 17,20β‐dihydroxy‐4‐pregnen‐3‐one and 17,20β,21‐dihydroxy‐4‐pregnen‐3‐one remained low and unchanged during the peak of the spermiation period, while thyroid hormones were high and fluctuated without exhibiting a trend consistent with spermiation. The observed endocrine profiles suggest that captivity can diminish plasma GtH II and triiodothyronine levels in striped bass. Transfer of spermiating males from large holding tanks to small spawning tanks reduced total expressible milt after 14 d, but treatment with a GnRHa‐implant restored milt volume, presumably due to the prolonged elevation of plasma GnRHa and GtH II induced by the GnRHa‐implant. Also, treatment with the GnRHa‐implant induced a two‐ to four‐fold elevation of expressible milt for at least 20 d compared to control fish, while resulting in only a 5 to 15% decrease in sperm density. It appears that captivity and hatchery operations can diminish milt production in striped bass, and that GnRHa‐delivery systems, via sustained elevation of plasma GtH II, can induce long‐term enhancement in milt volume without affecting sperm density greatly.
Chlorination of Channel Catfish Ponds
Authors: Potts Arthur C. , Boyd Claude E.
Published: April 2007

Abstract— Laboratory studies with pond water samples revealed that 5 mg/L active chlorine was needed to provide enough chlorine residual to reduce biological activity. Treatment of channel catfish ponds with repeated, 0.1‐mg/L doses of active chlorine from calcium hypochlorite at 6‐ to 8‐d intervals, as sometimes done by catfish farmers, had little influence on water quality. Dissolved oxygen, total ammonia‐nitrogen, and chlorophyll a concentrations and pH were similar between treated and control ponds. Concentrations of chemical oxygen demand and particulate organic matter were seldom different between treated and control ponds. Channel catfish survival and net production were not improved by chlorine treatment. Thus, chlorination of production ponds during the grow‐out period is not a useful technique. Treatment of sediment samples from ponds with up to 1,200‐mg active chlorinelkg soil did not reduce bacterial abundance, so chlorination of bottoms of empty ponds may not he an effective disinfection procedure. Chlorination of pond waters with 30‐mg/L active chlorine caused complete kill of bacteria 24 h after treatment, although heterotrophic bacteria quickly re‐populated the water. Thus, chlorination can be an effective way to disinfect ponds before stocking.
Effect of Reducing Dietary Digestible Energy to Protein Ratio on Weight Gain and Body Fat of Juvenile Channel Catfish Ictalurus punctatus1
Authors: Li Meng H. , Robinson Edwin H.
Published: April 2007

A laboratory feeding trial was conducted to evaluate the effects of reducing digestible energy to protein (DE:P) ratios of practical diets on body fat and weight gain of channel catfish. Five diets were formulated to contain 32, 28, or 24% crude protein with typical DE:P ratios of 8.5, 9.9, or 11.4 kcal/g protein, respectively, and 28% or 24% protein with a reduced DE:P ratio of 8.5 kcal/g protein. Cellulose was used to adjust the DE:P ratio. Juvenile channel catfish Ictalurus punctatus (initial weight: 5.2 g/fish) were fed the experimental diets twice daily to apparent satiation for 12 wk. Fish fed the 28% protein diet with a reduced DE:P ratio of 8.5 kcal/g protein gained less weight and converted feed less efficiently than those fed the 28% protein diet with a typical DE:P ratio of 9.9 kcal/g protein. Fish fed the 24% protein diet with a reduced DE:P ratio of 8.5 kcal/g protein had a similar weight gain but converted feed less efficiently than those fed the 24% protein diet with a typical DE:P ratio of 11.4 kcal/g protein. Weight gain and feed conversion efficiency of fish fed the 32% protein diet with a typical DE:P ratio of 8.5 kcal/g protein were higher than for fish fed other diets except those fed the 28% protein diet with a DE:P ratio of 9.9 kcal/g protein. There were no differences in feed consumption and survival among dietary treatments. Fillet fat of fish fed the 24% and 28% protein diets with a reduced DE:P ratio was lower than that of the fish fed diets containing the same protein concentrations with typical DE:P ratios. At a DE:P ratio of 8.5 kcal/g protein, there were no differences in fillet fat concentration among fish fed diets containing different protein concentrations. There were no differences in fillet protein, moisture, and ash between fish fed the 24% or 28% protein diets containing reduced and typical DE:P ratios. Results from this study show that reducing DE:P ratios in practical diets lowers body fat but also depresses weight gain of channel catfish; thus it would not be economical to use this strategy to reduce body fat of the fish.
Partitioning of Fish and Diet Selection as Methods for the Reduction of Cannibalism inParalichthys dentatusLarviculture
Authors: Francis A. Ward , Bengtson David A.
Published: April 2007

Partitioning of larvae and diet selection were examined as strategies to reduce cannibalism in summer flounderParalichthys dentatus. Methods of partitioning included physical grading by size, baffle interference, and a control. The baffle consisted of a barrier with cells 14‐mm square and walls 9‐mm high. The barrier was positioned horizontally at a depth where it would divide the tank into two equal volumes of water. Factors which may characterize cannibalism were quantified, including: total length, developmental stage, pigmentation, wet weight, and biomass. Engineered to reduce cannibalism, the baffle instead contributed to a decrease in survival for at least one experiment (P <0.05). Grading by size did not significantly increase survival over that of the untreated control (P >0.05). Mean developmental stage ofP. dentatusin the graded treatment was significantly less than fish in either the control or baffle treatments (P <0.05). A factorial design of partition strategy and weaning diet did not demonstrate any difference in survival or measured character (P >0.05). Finally, both inert feeds and liveArtemiasp. nauplii were examined for their contribution to the Occurrence of cannibalism. Predicted differences between live and artificial diets were not significant (P> 0.05). During experiments, cannibalism was principally observed in late larval and early juvenile stages and was not restricted to post‐metamorphic juveniles feeding on premeta‐morphic larvae. Methods normally employed to reduce cannibalism (partitioning of larvae and diet selection) do not appear to be effective forP. dentatus.
Bioassay Procedure for the Evaluation of Erythromycin Activity in Aquaculture Environments
Authors: Assaf Nasser A. , Pothuluri Jairaj V. , Wang Rong‐Fu , Cerniglia Carl E. , Moffitt Christine M.
Published: April 2007

A new bioassay procedure was developed for the detection of erythromycin in aquaculture samples using a strain of a Stenotrophomonas as an indicator organism. Conventional disk‐plate and well‐plate radial diffusion assay procedures were developed, as well as a third procedure using the same indicator organism in Luria‐Bertani (LB) broth, supplemented with the indicator dye Brilliant Black (40 μg/mL) in a multi‐well microtiter plate. For both the disk‐plate and well‐plate radial diffusion assays, the response reflected in the size (width) of the growth inhibition zone, which was linear over the tested concentration range of 0.05 to 2.0 μg erythromycidml. The limit of quantitation of the bioassay was at 0.05 μg erythro‐mycidml. Among the three methods of assay tested with Stenotrophomonas sp., the semi‐quantitative dye reduction method is easy to read and is not diffusion dependent. This method allows for processing of more samples and more replication on a single titer plate. This new indicator organism is specific for erythromycin when tested in the presence of other antibacterial agents, i.e., oxytetracycline (Terramycin®) and/or Romet‐Ma. This new bioassay procedure is suitable for quantitation of low concentrations of erythromycin in aquaculture water and sediment samples.
Wildlife‐Caused Losses for Producers of Channel Catfish Ictalurus punctatus in 1996
Authors: Wywialowski Alice P
Published: April 2007

The National Agricultural Statistics Service surveyed by telephone and mail in January and February 1997 all known producers of channel catfish letalurus punctatus to acquire current information about wildlife‐caused losses in calendar year 1996. Many producers tried to prevent wildlife‐caused losses of their catfish by shooting (57%), vehicle patrol (55%), or frightening (36%), at an estimated cost of >$5 million. Yet, 69% of catfish producers cited some wildlife‐caused losses. Birds were most frequently cited as a cause of losses, and double‐crested cormorants Phalacrocorax auritus was the species cited most frequently (53%). The next most frequently cited birds were herons Ardea spp. (48%), egrets Egretta spp. (16%), and pelicans Pelecanus spp. (8%). Muskrats Ondatra zibethicus were cited by 10% of producers, primarily for damaging dikes and roads. The main problems caused by wildlife were feeding on catfish (67%), injuring catfish (40%) or disturbing feeding patterns of the catfish (23%). The total estimated cost of losses was $12 million. Overall, wildlife damage and damage prevention may have cost catfish producers > $17 million, about 4% of the total $425 million of catfish sales in 1996. Of the 44% of all catfish producers who were familiar with Wildlife Services (WS), 51% had ever contacted WS for assistance, 55% used methods suggested by WS to reduce their losses, and 40% received direct assistance from WS in 1996. Mississippi producers, who most frequently received direct assistance from WS, had proportionately lower wildlife‐caused losses.
Effect of Ozone Treatment on Cultures of Nannochloropsis oculata, Isochrysis galbana, and Chaetoceros gracilis
Authors: Kuresity Nasir , Davis D. Allen , Arnold C. R.
Published: April 2007

This research evaluated ozone treatment of three unicellular algal species commonly used in the culture of marine larvae. Isochrvsis galbana and Nannochloropsis oculata were found to be resistant to total residual oxidants (TRO); whereas, Chaetoceros gracilis was relatively sensitive to TRO. Isochrvsis galbana remained in log‐phase growth after treatment with 0.05 mg/L to 0.50 mg/L TRO, and N. oculata exhibited strong growth after being exposed to TRO levels up to 0.67 mg/L. Only TRO levels of 0.92 mg/L and 0.90 tng/L reduced cell counts of N. oculata and I. galbana, respectively. Furthermore, algal cultures having higher concentrations at the time of ozone treatment may respond more favorably to the treatment. Initially, C. gracilis was reduced in cell count at TRO levels above 0.06 mg/L, but log‐phase growth was resumed 2 d after exposure to TRO levels as high as 0.31 mg/L. It is concluded that I. galbana and N. oculata can be successfully treated with ozone in the mass production stages without hampering the timely production of concentrated cultures. Although C. gracilis was found to be relatively sensitive, ozone treatment of starter cultures can be performed routinely with this species. We have demonstrated that ozone treatment of algal cultures is a feasible technique, but studies need to be conducted on ozone treatment of other species of unicellular algae and on ozone treatment of varying concentrations of algae in order to enhance the applications of this technique. Also, in order to determine the extent of disinfection of algal cultures, bacterial and viral composition of the cultures should be evaluated in future studies.
Vaccination of Mixed and Full‐Sib Families of Channel Catfish Ictalurus punctatus Against Enteric Septicemia of Catfish With a Live Attenuated Edwardsiella ictaluri Isolate (RE‐33)
Authors: Wise David J. , Klesius Phillip H. , Shoemaker Craig A. , Wolters William R.
Published: April 2007

These studies were conducted to evaluate the efficacy of a live attenuated Edwardsiella ictaluri vaccine against enteric septicemia of catfish. In one study channel catfish fingerlings (72 d of age post hatch) were immersed for 30 min in water containing E. ictaluri RE‐33 at dosages of 1 × 106, 1 × 107 and 2 × 107 CFU/ML of water. No mortalities were observed following vaccination. Following exposure to virulent Edwardsiella ictaluri the cumulative mortality of fish vaccinated with dosages of at least 1 × 107 CFU/mL were significantly lower than that of non‐vacccinated fish in both laboratory and field challenges. Vaccination with 1 × 106 CFU RE‐33mL provided some protection during the laboratory challenge but failed to protect fish under field conditions. In a second study, vaccination of 6 full‐sib families of channel catfish at a vaccine dosage of 1 × 107 CFU/mL resulted in a relative percent survival among families ranging from 67.1 to 100%. Significant differences in mortality were found among families and between vaccinated and unvaccinated groups, but there was no family by vaccine interaction. Families with the highest mortality after vaccination were also shown to have the highest mortality without vaccination (r = 0.82; P= 0.04).
Grazing Selectivity of Red Abalone Haliotis rufescens Postlarvae on Benthic Diatom Films under Culture Conditions
Authors: Siqueiros‐Beltrones David A. , Voltolina Domenico
Published: April 2007

The gut contents of Haliotis rufescens postlarvae that had grazed on a diatom film grown in PVC buckets were analyzed to determine selectivity in feeding. Species composition and abundances were compared to that of the surrounding film. Diatom samples were oxydized and mounted permanently, or observed directly by the squash technique under phase contrast microscopy. The surrounding flora yielded 111 taxa, while 64 species appeared in the gut contents. A high proportion of Pinnularia biceps v. minor and Navicula incerta (and others) in the gut contents, which were rare or absent from the samples of the surrounding flora, indicated grazing selectivity by the postlarvae. An analysis of similarity confirmed that samples from the gut contents could be grouped together and that they were clearly different from the surrounding flora.
Accelerated Growth, Gigantism and Likely Sterility in Autotransgenic Triploid Mud Loach Misgurnus mizolepis
Authors: Nam Yoon Kwon , Cho Hyo Jong , Cho Young Sun , Noh Jae Koo , Kim Chul Geun , Kim Dong Soo
Published: April 2007

Triploidy was induced in two selected lines of autotransgenic mud Ioach Misgurnus mizolepis containing no heterospecific genetic material. Cytological evaluations, including cellular DNA content, chromosome count, and erythrocyte measurement, proved the successful induction of triploidy. Patterns of Southern blot hybridization and tissue distribution of GH mRNA in autotransgenic triploids were similar to those of diploid autotransgenics. The autotransgenic triploids also displayed growth acceleration 22–25 times that of nontransgenic diploids, although the acceleration was relatively modest when compared to their diploid transgenic counterparts (more than a 30‐fold increase). Significantly improved feed conversion was observed in both autotransgenic diploids and triploids, ranging from 1.8 to 2.0 times that in nontransgenics. Autotransgenic triploids were sterile at gonadal level, evidenced by significantly retarded and abnormal gametogenesis. With the persistence of accelerated growth and enhanced feed conversion efficiency, the autotransgenic triploid mud loach may offer economic benefits to aquaculture. Total absence of heterospecific genetic material and sterility may also allay public concern regarding food safety and environmental risk of crossbreeding between transgenics and conspecific populations.