bluuebunny/crossref_metadata_2025 huggingface dataset:
Perpendicular magnetic anisotropy induced by a cap layer in ultrathin MgO/CoFeB/Nb
Authors: Cheng Tsung-I , Cheng Chih-Wei , Chern G.
Published: August 2012

Perpendicular magnetic anisotropy has been observed in MgO/CoFeB/Ta but not in MgO/CoFeB/Ru, indicating that the metal cap layer is crucial. In this study, we grew MgO/CoFeB (1.2 nm)/Nb (1–2.5 nm) by sputtering and found that the magnetic anisotropy depends upon the Na thickness. The easy axis is in-plane when x = 1 nm but changes to perpendicular when x ≥ 1.2, and a transition from in-plane to perpendicular is observed at x = 1.1 nm. Perpendicular magnetic anisotropy gradually decays as the x increases, showing that it only exists in a small window of the cap Nb layer within ∼2 nm.
A database for equations of state and resistivities measurements in the warm dense matter regime
Authors: Clérouin J. , Noiret P. , Blottiau P. , Recoules V. , Siberchicot B. , Renaudin P. , Blancard C. , Faussurier G. , Holst B. , Starrett C. E.
Published: August 2012

The aim of this paper is to provide experimental data on various expanded elements in the warm dense matter regime. The experiments were done on the experimental facility “enceinte à plasma isochore” and are evaluated through a thorough comparison with ab initio calculations, average-atom codes, and chemical models. This comparison allows for the evaluation of the experimental temperatures that are not accessible to the measurements and permits the building of useful data tables gathering energy, pressure, conductivity, and temperatures. We summarize experiments performed on aluminum (0.1 and 0.3 g/cm3), nickel (0.2 g/cm3), titanium (0.1 g/cm3), copper (0.3 and 0.5 g/cm3), silver (0.43 g/cm3), gold (0.5 g/cm3), boron (0.094 g/cm3), and silicon (0.21 g/cm3) for temperatures ranging from 0.5 eV to 3-4 eV.
Incorporation of lead and titanium into a porous alumina membrane during Pb(Zr0.52Ti0.48)O3 nanotube synthesis
Authors: Kyu Han Jin , Kim Jongok , Don Bu Sang
Published: August 2012

We report the identification and characteristics of lead aluminate (Pb2Al2O5 or PbAl12O19)/aluminum titanate (Al2TiO5) formed as a result of the interaction between a Pb(Zr0.52Ti0.48)O3 (PZT) precursor and a porous alumina membrane (PAM) during PZT nanotube synthesis. The surface morphology and composition of PZT nanotubes were examined as a function of the etching time and annealing temperature, and the diffusion of elements over nanometer length scales during PZT nanotube formation was investigated based on analysis using field emission transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray microscopy. As the annealing temperature increased, the volume of lead aluminate/aluminum titanate increased, suggesting that considerable diffusion of Pb and Ti occurred and, in turn, dramatically affected the nanotube characteristics. The diffusion of Pb and Ti was clearly evident, resulting in the formation of a distinct lead aluminate/aluminum titanate at the PZT nanotube/PAM interface.
Screening effect on the binding energy of the exciton in quantum wires
Authors: Zhai Li-Xue , Wang Yan , Liu Jian-Jun
Published: August 2012

This paper describes using the finite difference method to study the screening effect on the binding energy of excitons in quantum wires (QWRs). We have derived an analytical formula for the effective screened interaction potential between an electron and a hole in an exciton. The exciton binding energy as functions of the screening length, carrier density, and QWR width is calculated and is found to be sensitive to the screen length when the length is less than 1 × 103 Å. Furthermore, when the screen length is less than 3 × 102 Å, the exciton binding energy decreases rapidly with decreasing screen length. It is also found that the wider the QWR is, the more pronounced the screening effect will be. The transition from a dilute exciton gas to a dense electron-hole plasma in a QWR is clearly shown on a phase diagram for the carrier density-temperature plane.
Analog of the susceptibility spectrum for levitation forces between a superconductor and a permanent magnet
Authors: Sergeenkov S. , Sanchez E. S. , Salla R. V. F. , Rivera V. A. G. , Cichetto L. , Araújo-Moreira F. M.
Published: August 2012

We report on the measurements of both vertical and lateral levitation forces between a permanent magnet NdFeB and a polycrystalline YBa4Cu6O7−δ superconductor. The analysis of the obtained results revealed an interesting correlation between the behavior of the forces in the field-cooled and zero-field-cooled regimes, resembling the structure of the so-called susceptibility spectrum χ″(χ′). Such force-force diagrams can be useful for identifying flux distribution structure inside a superconducting material.
Oscillating plasma bubbles. IV. Grids, geometry, and gradients
Authors: Stenzel R. L. , Urrutia J. M.
Published: August 2012

Plasma bubbles are created in an ambient plasma. The bubble is formed inside a cavity bounded by a negatively biased grid. Ions are injected through the grid and neutralized by electrons from either the background plasma or an internal electron emitter. The external electron supply is controlled by the grid bias relative to the external plasma potential. When the electron flux is restricted to the ion flux, the sheath of the bubble becomes unstable and causes the plasma potential to oscillate near the ion plasma frequency. The exact frequency depends on the net space charge density in the bubble sheath. The frequency increases with density and grid voltage, provided the grid forms a parallel equipotential surface. The present investigation shows that when the Debye length becomes smaller than the grid openings the electron flux cannot be controlled by the grid voltage. The frequency dependence on grid voltage and density is modified creating frequency and amplitude jumps. Low frequency sheath oscillations modulate the high frequency normal oscillations. Harmonics and subharmonics are excited by electrons in an ion-rich sheath. When the plasma parameters vary over the bubble surface, the sheath may oscillate at different frequencies. A cavity with two isolated grids has been used to investigate anisotropies of the energetic electron flux in a discharge plasma. The frequency dependence on grid voltage is entirely different when the grid controls the energetic electrons or the bulk electrons. These observations are important to several fields of basic plasma physics, such as sheaths, sheath instabilities, diagnostic probes, current, and space charge neutralization of ion beams.
Energy states and carrier transport processes in metamorphic InAs quantum dots
Authors: Seravalli L. , Trevisi G. , Frigeri P. , Royce R. J. , Mowbray D. J.
Published: August 2012

Photoluminescence excitation spectroscopy is used to probe energy states and carrier transport in InAs quantum dot structures grown on InGaAs metamorphic layers, designed for room temperature emission at 1.3, 1.4, or 1.5 μm. The dominant spectral feature is shown to arise from the partially relaxed InGaAs confining layer. In structures with a low indium composition or thin InGaAs layer, a clear wetting layer feature is observed which acts as the dominant reservoir for carriers thermally excited from the quantum dots. Structures with high indium composition and/or thick InGaAs lack a wetting layer and carriers escape directly to the InGaAs layers.
Theoretical investigation of the electronic structures and carrier transport of hybrid graphene and boron nitride nanostructure
Authors: Sun Jia-Tao , Wee Andrew Thye Shen , Feng Yuan Ping
Published: August 2012

Recently hybridgraphene and hexagonal boron nitride (C-BN) nanostructures receive much research interest due to the complementary electronic properties. Graphene is a zero-gap semiconductor, while hexagonal boron nitride (h-BN) is a wide gap semiconductor. Here we studied the electronic structures and carrier transport of hybrid C-BN nanostructures by using first principles calculations and deformation potential theory. We have found that the physical quantities in these systems under study, band gap, effective mass, deformation potential, and carrier mobility, can be categorised into three different families depending on the width of graphene nanoribbon. This family behavior is similar to pristine armchair graphene nanoribbon, but with slight difference from the individual component. New opportunities of designing nanoelectric devices are discussed by utilizing the quantum confinement effect based on such kind of hybrid nanostructures.
Prevalence Effect in Haptic Search
Authors: Ishibashi Kazuya , Watanabe Ken , Takaoka Yutaka , Watanabe Tetsuya , Kita Shinichi
Published: August 2012

In visual search tasks, the ratio of target-present to target-absent trials has important effects on miss rates. In this study, we examined whether the target prevalence effect occurs in a haptic search task by using artificial tactile maps. The results indicated that target prevalence has effects on miss rates, sensitivity, and criterion. Moreover, an increase in miss rates in the low-prevalence condition (10%) was strongly correlated with a decrease in search termination times (target-absent reaction times). These results suggest that the prevalence effect on haptic search is caused by a decrease in the search termination time and a shift in decision criterion and a decrease in sensitivity.
Afterimages from Unseen Stimuli
Authors: Anstis Stuart , Geier Janos , Hudak Mariann
Published: August 2012

Observers adapted to a field of randomly coloured twinkling tiles, in which was embedded a faint, subthreshold green letter. Observers failed to discern this letter, but they readily reported its pink afterimage afterwards. This demonstrates a storage of changing colours over time; adaptation occurs for the average of each retinal point.
Examining Alternatives to Wavelet Denoising for Astronomical Source Finding
Authors: Jurek R. , Brown S.
Published: August 2012

The Square Kilometre Array and its pathfinders ASKAP and MeerKAT will produce prodigious amounts of data that necessitate automated source finding. The performance of automated source finders can be improved by pre-processing a dataset. In preparation for the WALLABY and DINGO surveys, we have used a test Hi datacube constructed from actual Westerbork Telescope noise and WHISP Hi galaxies to test the real world improvement of linear smoothing, the Duchamp source finder's wavelet denoising, iterative median smoothing and mathematical morphology subtraction, on intensity threshold source finding of spectral line datasets. To compare these pre-processing methods we have generated completeness-reliability performance curves for each method and a range of input parameters. We find that iterative median smoothing produces the best source finding results for ASKAP Hi spectral line observations, but wavelet denoising is a safer pre-processing technique. In this paper we also present our implementations of iterative median smoothing and mathematical morphology subtraction.
Explosive radiation of the genus Schizopera on a small subterranean island in Western Australia (Copepoda:Harpacticoida): unravelling the cases of cryptic speciation, size differentiation and multiple invasions
Authors: Karanovic Tomislav , Cooper Steven J. B.
Published: August 2012

A previously unsurveyed calcrete aquifer in the Yilgarn region of Western Australia revealed an unprecedented diversity of copepods, representing 67% of that previously recorded in this whole region. Especially diverse was the genus Schizopera, with up to four morphospecies per bore and a significant size difference between them. Aims of this study were to: (1) survey the extent of this diversity using morphological and molecular tools; (2) derive a molecular phylogeny based on COI; and (3) investigate whether high diversity is a result of an explosive radiation, repeated colonisations, or both, size differentiation is a result of parallel evolution or different phylogeny, and whether Schizopera is a recent invasion in inland waters. More than 300 samples were analysed and the COI fragment successfully amplified by PCR from 43 specimens. Seven species and one subspecies are described as new, and three possible cryptic species were detected. Reconstructed phylogenies reveal that both explosive radiation and multiple colonisations are responsible for this richness, and that Schizopera is probably a recent invasion in these habitats. No evidence for parallel evolution was found, interspecific size differentiation being a result of different phylogeny. Sister species have parapatric distributions and show niche partitioning in the area of overlap.
A morphometric approach supporting genetic results in the taxonomy of the New Zealand limpets of the Cellana strigilis complex (Mollusca : Patellogastropoda : Nacellidae)
Authors: Reisser Céline M. O. , Marshall Bruce A. , Gardner Jonathan P. A.
Published: August 2012

The New Zealand Cellana strigilis complex has been traditionally divided into six subspecies. Recent molecular investigations, however, revealed that the complex comprises two clades. In this paper, an additional morphometric analysis on 160 shells from the two clades confirms the need for taxonomic reconsideration of the C. strigilis complex. Here, two species are recognised in the Cellana strigilis group, a western species, C. strigilis (Hombron & Jacquinot, 1841), from South, Stewart, Snares, Auckland and Campbell islands, with Patella redimiculum Reeve, 1854 and C. strigilis flemingi Powell, 1955 as synonyms; and an eastern species, C. oliveri Powell, 1955, from Chatham, Bounty Islands and Antipodes Islands, with C. strigilis bollonsi Powell, 1955 and C. chathamensis of authors (not Pilsbry, 1891) as synonyms. Acmaea chathamensis Pilsbry, 1891 is based on mislocalised foreign shells, probably C. rota (Gmelin, 1791) from the Red Sea. A neotype is designated for P. strigilis Hombron & Jacquinot, 1841, lectotypes are designated for P. redimiculum Reeve, 1854 and A. chathamensis Pilsbry, 1891, and a type locality is selected for P. redimiculum.
Linking humans and fire: a proposal for a transdisciplinary fire ecology
Authors: Coughlan Michael R. , Petty Aaron M.
Published: August 2012

Human activity currently plays a significant role in determining the frequency, extent and intensity of landscape fires worldwide. Yet the historical and ecological relationships between humans, fire and the environment remain ill-defined if not poorly understood and an integrative approach linking the social and physical aspects of fire remains largely unexplored. We propose that human fire use is ubiquitous and evidence that historical fire patterns do not differ from non-anthropogenic fire regimes is not evidence that humans did not practice fire management. Through literature review and the presentation of two case studies from the south-eastern USA and tropical Australia, we discuss how the study of fire ecology can benefit from paying attention to the role of humans in three thematic areas: (1) human agency and decision processes; (2) knowledge and practice of landscape fire and (3) socioecological dynamics inherent in the history of social systems of production and distribution. Agency, knowledge of fire ecology and social systems of production and distribution provide analytical links between human populations and the ecological landscape. Consequently, ignitions ultimately result from human behaviours, and where fire use is practised, ignitions result from decision process concerning a combination of ecological knowledge and belief and the rationale of livelihood strategies as constrained by social and ecological parameters. The legacy of human land use further influences fuel continuity and hence fire spread.
Egg Transfer to Increase Productivity and Predictability in Bluegill Fry Production
Authors: Arslan Tulin , Phelps Ronald P
Published: August 2012

The traditional spawning–rearing pond method used in seed production for bluegill Lepomis macrochirus has shortcomings that inhibit meeting the demand for high numbers of uniform-size fry and fingerlings by recreational fisheries and the developing aquaculture industry. In this study, the feasibility of an egg transfer method in bluegill seed production was evaluated. For this, 30 female and 15 male broodfish were spawned in artificial nests located in 15-m2 outdoor tanks. The fish were allowed to spawn for 21 d in each of three trials conducted between June 22 and September 3. Nests with eggs were collected daily, and the eggs were either hatched in flow-through aquaria or separated from the nest using a 1.5% sodium sulfite solution and hatched in McDonald jars. Short sodium sulfite treatments were effective in separating eggs from the nest, and hatching of eggs still attached to the nests in flowing-water aquaria was reliable and required less labor. Compared with the traditional method, egg transfer improved both the number produced (mean ± SD, 33 ± 17 fry/g of female body weight per 21 d and 433 ± 243 fry/m2 per day) and the efficiency of producing young. With the transfer method, high numbers of uniform-size fry can be produced in a short period using fewer brooders and less space than in the spawning–rearing pond method.

Received February 23, 2010; accepted September 2, 2010
Replacement of Fish Meal with Ethanol Yeast in the Diets of Sunshine Bass
Authors: Gause Brian , Trushenski Jesse
Published: August 2012

Increasing demand and rising costs of fish meal (FM) coupled with static landings of reduction fisheries have made continued use of FM-rich aquaculture feeds environmentally and economically unsustainable. Animal- and plant-derived proteins have been investigated as alternatives to FM, with variable success. Observed limitations of commonly used alternative proteins have led nutritionists to investigate new alternatives to FM. Ethanol yeast, a co-product of bioethanol production and potential new alternative protein source, was evaluated as a FM replacement in the diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Five diets were evaluated, including a control diet containing 30% FM and four experimental diets (22.5, 15, 7.5, and 0% FM) in which 25, 50, 75, or 100% of the FM content was replaced with ethanol yeast. Juvenile sunshine bass (∼16 g) were fed twice daily to apparent satiation for 45 d. Production performance of sunshine bass was not impaired by partial FM replacement and in some cases was marginally improved by dietary inclusion of ethanol yeast. Feed conversion ratio, specific growth rate, and feed intake were equivalent among fish fed the control, 22.5% FM, 15% FM, and 7.5% FM feeds; weight gain was significantly increased in the 15% FM group compared with the control. However, complete replacement (0% FM) resulted in significantly impaired growth performance and conversion efficiency. Whole-body composition did not differ with respect to moisture, ash, or protein content; however, crude lipid content was significantly elevated in the 7.5% FM treatment, suggesting a protein–energy imbalance in this formulation. Although our study was a short-term screening trial, based on our results we suggest that an optimal level of FM in ethanol-yeast-based feeds for sunshine bass would be between 7.5% and 15%.

Received March 15, 2010; accepted June 5, 2010
Stream Salinization by Inland Brackish-Water Aquaculture
Authors: Pine Harvey J , Boyd Claude E
Published: August 2012

Commercial aquaculture is performed in several regions of Alabama, with much of the production being concentrated in the Blackland Prairie region. Portions of this region have access to aquifers containing brackish water with salinities ranging from 1 to 10 g/L that are currently supplying water to several pond-based aquaculture facilities. The use of low-salinity water has been beneficial for the production of channel catfish Ictalurus punctatus, and such water has been found suitable for the culture of marine species such as the Pacific white shrimp Litopeneaus vannamei. Though the use of this resource has been recognized as beneficial, the potential for it to salinize local surface waters is unknown. An element of concern associated with the salinization of streams is the chloride ion. The U.S. Environmental Protection Agency has established an instream standard chloride concentration of 230 mg/L for freshwater, which has been adopted by the Alabama Department of Environmental Management. Investigation into stream salinization resulting from low-salinity aquaculture in western Alabama was initiated in June 2006. Eight streams were sampled bimonthly for salinity, conductivity, and chloride concentration. Four of the eight streams are associated with aquaculture production facilities and receive effluents from these operations. The remaining four streams are located near the aquaculture facilities but do not receive effluents or runoff from them. The facilities include a catfish fingerling facility, a catfish production facility, a shrimp production facility, and a combined catfish–shrimp production facility. The streams associated with the aquaculture production facilities were sampled at sites both upstream and downstream from them. Sampling through April 2007 revealed that the streams associated with the aquaculture facilities had chloride concentrations exceeding 230 mg/L at various times during the year. These results indicate that these facilities are contributing to stream salinization.

Received January 29, 2010; accepted August 18, 2010
Efficacy and Toxicity of Iodine Disinfection of Atlantic Salmon Eggs
Authors: Chalupnicki Marc A , Ketola H George , Starliper Clifford E , Gallagher Dennis
Published: August 2012

Recent interest in the restoration of Atlantic salmon Salmo salar in the Great Lakes has given rise to new culture techniques and management programs designed to reduce pathogen transmission while stabilizing and enhancing wild populations. We examined the toxicity of iodine to Atlantic salmon eggs and its effectiveness as a disinfectant against bacteria on egg surfaces. We spawned and fertilized eight gravid Atlantic salmon from Cayuga Lake, New York, and exposed their eggs to 10 concentrations of iodine (5, 10, 50, 75, 100, 500, 750, 1,000, 5,000, and 7,500 mg/L) for 30 min during water hardening. An additional subsample of unfertilized eggs was also exposed to some of the same concentrations of iodine (5, 10, 50, 75, and 100 mg/L) to determine the efficiency of disinfection. Viable eggs were only obtained from four females. Survival of eggs to the eyed stage and hatch tended to be reduced at iodine concentrations of 50 and 75 mg/L and was significantly reduced at concentrations of 100 mg/L iodine or more. We calculated the concentrations of iodine that killed 50% of the Atlantic salmon eggs at eye-up and hatch to be 175 and 85 mg/L, respectively. Aeromonas veronii, A. schubertii, A. hydrophila, A. caviae, Plesiomonas shiggeloides, and Citrobacter spp. were the predominant bacteria present on the surface of green eggs and were significantly reduced by an iodine immersion. The use of iodine as a disinfectant on Atlantic salmon eggs was effective at low concentrations (50–75 mg/L), for which toxicity to Atlantic salmon was minimal.

Received June 8, 2010; accepted September 19, 2010
Nutrient Manipulation to Control the Toxic Alga Prymnesium parvum: Verification of Treatments and Resolution of the Issue of Elevated pH
Authors: Kurten Gerald L , Barkoh Aaron , Begley Drew C , Fries Loraine T
Published: August 2012

In previous mesocosm experiments simulating aquaculture ponds, we found that fertilization with inorganic nitrogen (N) and phosphorus (P) eliminated the toxigenic alga Prymnesium parvum. However, the effective inorganic fertilization regimes (three applications of 300 μg N/L plus 30 μg P/L or 117 μg N/L plus 15 μg P/L per week) produced high pH and un-ionized ammonia (UIA) levels known to reduce the survival of sensitive fish species. In follow-up studies, lower UIA levels were achieved, but the issue of high pH remained unresolved. In the present study, we used hatchery ponds to examine the effects of the most effective inorganic fertilization regimes in combination with a standard cottonseed meal fertilization regime on P. parvum, pH, water quality, chlorophyll a, and zooplankton. Cottonseed meal was used to counter the elevated pH caused by inorganic fertilization. The results confirmed the efficacy of inorganic fertilization in controlling P. parvum in ponds, but the effect was dependent on the doses of N and P. Ponds with the highest dose of N and P had the fastest decline in ichthyotoxicity and P. parvum density. The addition of inorganic fertilizers to the standard cottonseed meal regime also improved chlorophyll-a levels and zooplankton abundance. The amplitudes of diel dissolved oxygen concentration and the risk of low concentrations of dissolved oxygen in the morning were greater in these ponds than in ponds fertilized with cottonseed meal alone. Also, pH was not reduced to safe levels for Morone spp. fry and fingerlings. Reducing pH to levels that are safe for fish is still a challenge that has to be meet before implementing this P. parvum management technique in ponds where pH-sensitive fish are reared. The timing of pond filling and fertilization to achieve P. parvum control before stocking the fish also needs refinement under this management strategy.

Received May 6, 2010; accepted September 9, 2010
Dietary Calcein Marking of Shovelnose Sturgeon and the Effect of Sunlight on Mark Retention
Authors: Honeyfield Dale C , Kindschi Greg A , Bell Thomas A , Mohler Jerre W
Published: August 2012

Calcein, a fluorochrome dye, is a potential fish-marking agent that has not been evaluated in sturgeon. Shovelnose sturgeon Scaphirhynchus platorynchus (average weight, 9.7 g) were fed calcein, immersed in a calcein bath, or left unmarked to determine calcein mark intensity. In the first study, six treatments were evaluated in a two-by-three factorial arrangement. Feed was formulated with 2.0 g of SE-MARK/kg either as powder or in an encapsulated form. Sturgeon were fed the test diets for 5, 10, or 15 d. They readily ate feed containing powdered or encapsulated calcein. Sturgeon fed powdered calcein had more brilliant marks than those fed encapsulated calcein (8.27 versus 4.66 lm; P < 0.03) 6 months postexposure. Fish fed calcein for 15 d (11.26 lm) were more brilliant (P < 0.002) than fish fed for either 5 d (3.02 lm) or 10 d (5.11 lm). Post hoc comparison of the three treatment groups showed that sturgeon fed powdered calcein for 15 d (14.06 lm) were brighter (P < 0.01) than fish fed encapsulated calcein (8.46 lm) or fish immersed in calcein (9.68 lm). In the second study, previously marked sturgeon were exposed to sunlight for 14 months to determine their retention of calcein marks. Dorsal marks were no longer visible on fish exposed to 100% sunlight after 8 weeks. Most but not all fish exposed to 20% sunlight had no discernable dorsal marks after 8 weeks, but ventral marks at the pectoral fin girdle were present on all fish in the 0% and 20% sunlight exposure treatments. Feeding calcein for 15 d appears to have excellent potential for practical application, such as distinguishing hatchery-reared from wild fish. Ventral calcein marks remained visible after 14 months of exposure to 20% sunlight when sturgeon were reared in clear water.

Received April 2, 2010; accepted September 22, 2010
Use of Corn Gluten Feed and Cottonseed Meal to Replace Soybean Meal and Corn in Diets for Pond-Raised Channel Catfish
Authors: Li Menghe H , Robinson Edwin H , Bosworth Brian G , Oberle Daniel F , Lucas Penelope M
Published: August 2012

The prices of soybean meal and corn—the two most commonly used, traditional feed ingredients in channel catfish diets—have increased dramatically in recent years. Using less-expensive alternative feed ingredients to partially replace soybean meal and corn would reduce feed cost. The present study evaluated the use of corn gluten feed and cottonseed meal, two promising alternative feedstuffs, as replacements for soybean meal and corn in diets for pond-raised channel catfish Ictalurus punctatus. Five isonitrogenous (28% crude protein) diets that used corn gluten feed and cottonseed meal (approximately 1:1 ratio) to replace 0, 25, 50, 75, or 100% of the soybean meal in the control diet were evaluated. The level of corn in the diet decreased as those of corn gluten feed and cottonseed meal increased. Stocker-size channel catfish (mean initial weight = 0.175 kg/fish) were stocked into twenty 0.05-ha earthen ponds at a rate of 14,830 fish/ha. Fish were fed once daily to apparent satiation over a growing season. Net yield, carcass and fillet yield, and fillet protein and fat levels decreased and the feed conversion ratio increased linearly as soybean meal replacement levels increased. These results demonstrate that a maximum of 50% of the soybean meal in channel catfish diets may be replaced (soybean meal was reduced from 51.4% to 25.7%) by a combination of corn gluten feed and cottonseed meal (up to 20% of each in the diet) without markedly affecting the physical quality of feed pellets, fish growth, processed yield, and body composition. The poor performance of diets containing high levels of corn gluten feed and cottonseed meal are probably a result of high fiber, low digestible energy, or both.

Received June 1, 2010; accepted October 1, 2010
Toxicity of Rotenone to Giant River Freshwater Prawn Macrobrachium rosenbergii
Authors: Ogunsanya Tiffany , Durborow Robert M , Webster Carl D , Tidwell James H , Coyle Shawn , Thompson Kenneth , Jarboe Herman H , Straus David L , Wang Changzheng , Huang Lingyu
Published: August 2012

Aquaculturists have often suffered predation losses in the production of freshwater giant river prawn Macrobrachium rosenbergii due to the presence of wild fish species in culture ponds. The piscicide rotenone is widely used to remove undesirable fish species from ponds. Although evidence in the technical literature suggests that crustaceans generally have a higher tolerance to rotenone than fish, there are currently no data on the acute or chronic toxicity of rotenone to juvenile freshwater prawns. In this study, two static acute-toxicity bioassays (96 h) were conducted using Prentox Prenfish (5% active ingredient) rotenone to determine the median lethal concentration (LC50) for juvenile freshwater prawns (average weight = 0.55 g, SD = 0.25; length = 41.43 mm, SD = 6.45). In bioassay 1, prawns were exposed to rotenone concentrations of 1.0, 3.0, 5.0, and 10.0 mg/L. In bioassay 2, prawns were exposed to rotenone concentrations of 2.2, 3.6, 6.0, 10.0, and 16.7 mg/L. All rotenone concentrations used in the study were based on the total product of the commercial rotenone formulation. The LC50 calculated in bioassay 1 was 6.2 mg/L, and the LC50 calculated in bioassay 2 was 7.5 mg/L. Freshwater prawns were able to tolerate 3.0 to 3.6 mg/L of rotenone with no mortality or apparent adverse effects during the study. Prawns held at the end of each bioassay for 5 d showed no signs of delayed effects from rotenone exposure. Data from this study indicate that juvenile prawns should be able to tolerate the concentrations of rotenone required to eradicate certain problematic wild fish species.

Received April 29, 2010; accepted October 1, 2010
Effect of Juvenile Length on Chinook Salmon Survivals at Four Hatcheries in Washington State
Authors: Tipping Jack M
Published: August 2012

In 3 years at four Washington State hatcheries, a total of 10 groups of juvenile Chinook salmon Oncorhynchus tshawytscha were length-sorted and coded-wire-tagged before release via the AutoFish System (Northwest Marine Technology, Shaw Island, Washington). After tagging, the length-groups were combined at each hatchery and reared through spring release. The release groups comprised (1) lower Columbia River yearling spring Chinook salmon (four releases), (2) lower Columbia River fall Chinook salmon subyearlings (three releases), (3) mid-Columbia River fall Chinook salmon subyearlings (two releases), and (4) Puget Sound summer Chinook salmon subyearlings (one release). In three releases, large juveniles at tagging produced significantly more jack returns (recovered at the hatchery or on spawning grounds in the year of release or the following year) than did small juveniles, while in one release mid-sized and small juveniles each produced significantly more jack returns. In 7 of 10 releases, larger juveniles produced significantly more adult returns than smaller fish; there was no significant difference in 3 releases. If the smaller fish can be partitioned out and growth-accelerated as juveniles, and if they subsequently survive to adulthood at the same rate as their larger cohorts, there is potential to increase adult survival by about 33% at little additional cost.

Received May 18, 2010; accepted September 22, 2010
Broodstock Selection Criteria for Induced Spawning of Channel Catfish for the Production of Channel × Blue Catfish Hybrid Fry and the Influence of Temperature
Authors: Phelps Ronald P , Hastey Ryan , Broach Jason , Pendetar Alden , Linley Laban , Papanikos Nikolaos , Dunham Rex A
Published: August 2012

Hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish I. furcatus) can be obtained by induced spawning and artificial fertilization; the results, however, are variable. A threshold degree of maturity must be reached before broodfish can be induced to spawn, but selection of such fish can be very subjective. In the present study, female brood channel catfish were classified subjectively as poor, fair, or good as well as on the basis of body weight, total body length, body width and girth, and the ratios of these measurements. Brood females were held at 24, 26, and 28°C in 100-L aquaria and injected with synthetic analogues of luteinizing hormone releasing hormone at 20 μg/kg, followed 12 h later by an additional injection of 100 μg/kg. Data were collected regarding spawning success, time to egg release following injection, fecundity, egg diameter, hatching, and survival rates. For the population as a whole at all three temperatures the spawning rate was 73.8%, but among females that met certain selection criteria greater spawning rates occurred. Females with a length: body width value of less than 5.5 had a spawning rate of 88.9%, and those subjectively classified as good had a spawning rate of 85.7%. The temperature at which broodstock were held affected the spawning rate; females classified as fair and good had spawning rates of 52.9, 82.4, and 95.5% at 24, 26, and 28°C, respectively. Females classified as good spawned earlier than lesser-quality fish. Likewise, females with length: girth values of 1.8 or less or length: width values of 5.0 or less spawned sooner than females with higher values. Brood selection criteria also resulted in selected subsets with greater fecundities, larger egg diameters, and, in some cases, an overall greater production of swim-up fry per kilogram of female.

Received August 13, 2010; accepted October 11, 2010
Selective Fatty Acid Metabolism, Not the Sequence of Dietary Fish Oil Intake, Prevails in Fillet Fatty Acid Profile Change in Sunshine Bass
Authors: Trushenski Jesse T , Gause Brian , Lewis Heidi A
Published: August 2012

Increasing prices of fish oils (FOs) that are rich in long-chain (LC) polyunsaturated fatty acids (PUFAs) have led to increased implementation of plant-derived oils in aquaculture feeds. Use of diets that contain alternative lipids will affect the fillet fatty acid (FA) profile; therefore, the fish may be “finished” to augment fillet LC-PUFA content before harvest. Understanding tissue FA profile change and selective metabolism of FAs in sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) may allow finishing strategies to be optimized for this taxon. We evaluated whether the sequence of dietary LC-PUFA provision affects tissue composition of sunshine bass and whether profile change is similar after a switch to or from an LC-PUFA-rich feed. Sunshine bass were fed practical feeds (∼45% protein, ∼14% lipid) containing FO (rich in LC-PUFAs) or corn oil (CO; rich in medium-chain [MC] PUFAs) according to four regimens: FO feed exclusively, CO feed exclusively, or switching from one feed to the other halfway through the trial (from CO to FO or from FO to CO). Administering the FO and CO feeds exclusively or in alternation did not significantly affect production performance. Fillet FA profile changed little for fish that received the exclusive FO and CO regimens and essentially became slightly more FO-like and CO-like, respectively. Fillet LC-PUFA and MC-PUFA levels were comparable in the alternating FO-to-CO and CO-to-FO groups at harvest. However, the relative change in profile differed considerably; the increase in fillet LC-PUFAs for the CO-to-FO group was significant, but the corresponding increase in MC-PUFAs for the FO-to-CO group was much greater. This suggested that certain PUFAs were actively included or retained (or both) within the fillet lipid, particularly 18:2(n-6) (abundant in CO), which can “outcompete” LC-PUFAs for fillet deposition. Although there appears to be selection for and against the incorporation of certain FAs into fillet tissue, whether these FAs are consumed earlier or later during juvenile growth appears to have little effect on final tissue composition.

Received January 16, 2010; accepted April 21, 2010
Differential Incorporation of Dietary Fatty Acids from Flax and Fish Oils into Lipid Classes of White Bass Ova
Authors: Lewis Heidi A , Trushenski Jesse T , Lane Ryan L , Kohler Christopher C
Published: August 2012

The extent to which flax oil can replace fish oil in diets fed to female broodstock of white bass Morone chrysops was determined by evaluating growth performance and the fatty acid (FA) profile of ovum lipid classes. Four experimental diets containing increasing levels of flax oil as 0, 33, 67, and 100% replacement of menhaden (Brevoortia spp.) fish oil were fed to female white bass for 30 weeks prior to spawning. Overall, growth and survival were unaffected when flax oil replaced fish oil in the diets. However, ovum FA composition did differ by lipid class and according to dietary intake. The FA profile of the neutral lipid classes largely resembled dietary intake, resulting in monounsaturated FAs (MUFAs) and long-chain polyunsaturated FAs (LC-PUFAs; FAs with ≥20 carbons and ≥3 double bonds) as the most predominant FAs found within ova produced by 100% fish-oil-fed broodstock, while MUFAs and 18-carbon PUFAs dominated the ovum neutral lipid in females from the 100% flax oil treatment. Although the phospholipid fraction of ova produced by the 100% flax-oil-fed broodstock was also significantly enriched with 18-carbon PUFAs, accumulation of these FAs did not displace n-3 LC-PUFAs as comparable levels of n-3 LC-PUFAs were found in both the 100% fish oil and 100% flax oil treatments. Overall, flax oil has potential for use as an alternative to menhaden fish oil in diets for female white bass broodstock without altering phospholipid LC-PUFA content. However, further investigation is needed to determine how these modifications to ovum FA profile affect embryonic and larval survival.

Received January 19, 2010; accepted August 17, 2010
Classification and Quantification of Phospholipids and Dietary Effects on Lipid Composition in Pacific White Shrimp Litopenaeus vannamei
Authors: Ju Zhi Yong , Forster Ian , Dominy Warren , Lawrence Addison
Published: August 2012

The phospholipid (PL) composition of Pacific white shrimp Litopenaeus vannamei and the diets on which they were reared during an 8-week indoor feeding trial was characterized. Nine PL classes, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidic acid, and phosphatidylserine, were detected and quantified in shrimp, diets, and feed ingredients by high-performance liquid chromatography. Total PL comprised the majority of total lipid—over 69.5% in shrimp tail muscle and over 60.1% in the shrimp whole body. The PC, PE, and PI classes were the most abundant, comprising over 40, 35, and 15%, respectively, of the PL in shrimp tails. Cardiolipin and ceramides were also detected in the shrimp whole body. Dietary crude protein content (40% versus 35%) significantly affected the PL composition of the shrimp whole body. Addition of shrimp floc (suspended particles from shrimp culture) to a 40% crude protein diet yielded higher Pacific white shrimp growth and produced larger-sized shrimp but did not affect the composition of shrimp PL. These results demonstrate the contribution of PLs to the high nutritional value of shrimp meat.

Received January 19, 2010; accepted October 9, 2010
Skin Color Characterization in Rainbow Trout by Use of Computer-Based Image Analysis
Authors: Colihueque Nelson , Parraguez Margarita , Estay Francisco J , Diaz Nelson F
Published: August 2012

Back, flank (reddish band along the lateral line and below the lateral line), and belly regions of cultured rainbow trout Oncorhynchus mykiss were characterized in terms of skin coloration, spottiness, and darkness by using computer-based image analysis as an approach to separate fish into desirable back color categories for market and export. Three highly represented colors were observed on the back (mean ± SE percentage of area covered by the given color): blue or sky-blue, 18.0 ± 1.8%; yellow, 13.4 ± 1.5%; and green, 66.1 ± 2.0%. Individuals with a high frequency of these colors on the back (at least 50% of area covered by a given color) were reclassified into groups exhibiting a yellowish back color (YB), a bluish back color (BB), or a greenish back color (GB) to determine whether the BB group presented differences in various skin color variables when compared with the other back color groups; an undefined back color (UB) group (fish for which all colors had less than 50% coverage) was also used in these comparisons. The number and size of dark spots (mean ± SE) on the back was significantly smaller in the BB group (2.3 ± 0.3 spots/cm2; 1.3 ± 0.2% of area covered by spots/cm2) than in the YB group (3.4 ± 0.2 spots/cm2; 1.9 ± 0.1% of area covered by spots/cm2); furthermore, skin darkening on the back as measured in grayscale space (where 0 = black, 255 = white) was slightly greater in the BB group (58.2 ± 3.9) than in the GB group (80.7 ± 2.8). In the lateral band along the flank, the percentage of area covered by purple was significantly lower in the BB group (7.1%) than in the UB group (27.5%). Skin darkening of the back and darkening of the belly demonstrated a significant positive correlation in the BB group (r = 0.558, P < 0.05). Discriminant function analysis clearly distinguished the BB group from the other back color groups based on color profile. These results support the fact that the BB group, more commonly referred to as “blue back” rainbow trout, presents a color pattern of high commercial interest that can be used to improve the external appearance of farmed rainbow trout. Furthermore, computer-based image analysis was shown to be an effective technique for objectively measuring skin color to categorize rainbow trout into particular color patterns.
Chloramine-T Margin-of-Safety Estimates for Fry, Fingerling, and Juvenile Rainbow Trout
Authors: Bowker James D , Carty Daniel , Smith Charlie E , Bergen Silas R
Published: August 2012

Chloramine-T (CLT) is a candidate for approval for use in U.S. aquaculture to control mortality in freshwater-reared salmonids caused by bacterial gill disease (causative agent, Flavobacterium branchiophilum). The proposed treatment regimen is to administer CLT at 12–20 mg/L in a static or flow-through bath for 60 min/d on three alternate or consecutive days. To estimate a CLT margin of safety, defined as the highest dosing regimen above the proposed maximum therapeutic regimen at which no adverse effects are observed, we conducted seven experiments with fry, fingerling, and juvenile rainbow trout Oncorhynchus mykiss that examined mortality and an eighth experiment that examined mortality, gross pathology, and histopathology after CLT exposure. In each experiment, triplicate groups of fish were exposed to a range of CLT concentrations representing 0, 1, 1.5, 2, 2.5, 3, 3.5, 4, or 5× the highest proposed dose (20 mg/L) for 3× the proposed treatment duration (60 min) on three alternate or consecutive days at 8°C or 14°C. The survival of fry and fingerlings was unaffected by exposure to CLT concentrations as high as 100 and 60 mg/L, respectively (survival = 97.3–100%). Although the survival of juvenile fish was unaffected by exposure to 20 mg/L, exposure to higher CLT concentrations significantly reduced survival (≤10.0% at 100 mg/L). Across experiments, 92% of all mortalities occurred within 20 h of the first exposure to CLT. The histopathological changes of most concern were associated with gill tissues, but these were evident only in moribund fish exposed to doses of 60 mg/L or higher. Based on analysis of the survival data, the margin-of-safety estimates were approximately 100 mg/L for rainbow trout fry, at least 60 mg/L for fingerlings, and 50–60 mg/L for juveniles. Tissue responses to CLT at these concentrations were minor and did not warrant decreasing these estimates.
Sex Determination of Yellow Perch by External Morphology
Authors: Malison Jeffrey A , Held James A , Kaatz Sarah E
Published: August 2012

We developed a method of using external morphological characteristics to determine the sex of yellow perch Perca flavescens. The characteristics used were (1) the shape of the urogenital opening, (2) the shape of the anterior edge of the urogenital opening when thumb pressure was applied to the abdomen just anterior to the anus, and (3) the presence or absence of swelling around the anus. In females, the urogenital opening was crescent or half-moon shaped, its anterior edge remained linear when pressure was applied to the abdomen, and a ring-shaped area of swelling was present around the anus. In males, the urogenital pore was circular, its anterior end distended to a V or U shape (pointed anteriorly) when the abdomen was pressed, and the area around the anus was not generally swollen. The accuracy of using this method was 97.4% for fish 190–280 mm total length, 93.1% for fish 111–150 mm, and 82.7% for fish 80–110 mm.
Evaluation of Selected Commercial Starter Feeds for Sunfish Fry Culture
Authors: Dudenhoeffer Gregory A , Wetzel James E , Omara-Alwala Thomas R
Published: August 2012

Sunfishes Lepomis spp. are cultivated as sport fish, and recently interest has been shown in culturing them as a food fish based on commercially available feeds that vary in composition according to the life stage of the fish. We evaluated seven commercial larval starter feeds with northern bluegill L. macrochirus macrochirus and redear sunfish L. microlophus in the effort to relate growth performance to diet nutrient composition. The dependent variables were production weight, survival rate, feed conversion ratio, and mean individual weight and length. The proximate composition and fatty acid and amino acid compositions of feeds were related to the dependent variables. Survival rate ranged from 84% to 96% for bluegills and from 15% to 35% for redear sunfish, and individual mean weights ranged from 67 to 238 mg and from 31 to 78 mg for these two species. Relating the compositional analysis of feeds to the dependent variables indicated that isoleucine influenced mean individual weight for both species. Northern bluegill growth performance suggested a negative correlation with carbohydrates, while redear sunfish growth indicated a positive relationship with energy. This study shows that commercial starter feeds can vary greatly in how they influence sunfish growth performance. Further study is needed to determine what dietary variables, including factors other than nutrient profiles, are most important.