bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Prevention and Treatment of Winter Saprolegniosis (“Winter Kill”) in Channel Catfish Ictalurus puncfatus1
Authors: Li Meng H. , Wise David J. , Robinson Edwin H.
Published: April 2007

The efficacies of formalin, potassium permanganate, sodium chloride, and copper sulfate as prophylactic treatments for saprolegniosis (“winter kill”) in channel caffish Icralums puncratus were evaluated. Formalin and copper sulfate were also evaluated as postinfective treatments for the disease. Each of the five experiments was conducted with 5–to 7‐g channel catfish placed in static water aquaria maintained in refrigerated tanks. Water temperature was reduced from 25 to 10 C within 36 h and maintained at 10 ± 0.5 C for 28 d. Fish were exposed to cultured Saprolegnia sp. at 20 C, and morbidity and mortality data were recorded for 28 d. Saprolegnia sp.‐associated mortalities occurred 7–10 d after exposure. Formalin (25 mg/L) was effective as both a prophylactic and postinfective treatment for saprolegniosis. Copper sulfate was effective in preventing saprolegniosis at a concentration of 0.1 mg/L, but was ineffective as a postinfective treatment. Sodium chloride at 5,000 mg/L was effective in preventing saprolegniosis, but was not practical for use in the commercial catfish industry. Potassium permanganate (up to 0.5 mg/L) was not effective in preventing or treating saprolegniosis in channel caffish. Based on the results of this study, it may be possible to prevent saprolegniosis in channel catfish using formalin or copper sulfate during winter when fish are immunosuppressed by rapid decreases in water temperature or to treat infected fish with formalin. However, the routine use of chemicals to control this disease should not be recommended until studies on their efficacy under typical caffish culture conditions and the effect of long‐term use of chemicals on fish and on the environment are completed.
Evidence for Control of Water Quality in Channel Catfish Ictalurus punctatus Ponds by Phytoplankton Biomass and Sediment Oxygenation
Authors: Hargreaves John A. , Tucker Craig S.
Published: April 2007

A data set describing annual variation of water quality in ten commercial channel catfish Ictalurus punctatus ponds was subjected to exploratory statistical analysis to infer ecological processes affecting pond water quality. Two factors explained 67% of the variation in concentrations of water quality variables. The first factor (Factor 1) explained 49% of the variance and was associated with a large negative loading by total ammonia‐nitrogen and large positive loadings by total nitrogen, total phosphorus, chemical oxygen demand, and chlorophyll a. Factor 1 was interpreted with respect to factor loadings to represent the effect of phytoplankton biomass. The second factor (Factor 2) explained an additional 18% of the variance and was associated with a large negative loading by soluble reactive phosphorus and large positive loadings by nitrite‐nitrogen and, to a lesser extent, nitrate‐nitrogen. Factor 2 was interpreted to be related to variation in pond sediment oxygenation. Although factor analysis indicated the overwhelming effect of phytoplankton biomass on water quality, opportunities for management of phytoplankton communities in large commercial aqua‐culture ponds are limited. However, maintenance of an oxidized sediment‐water interface may improve water quality by limiting the diffusion of reductant‐soluble phosphorus from sediment to water and increasing sediment nitrification rates.
Effect of Dietary Protein Level on Apparent Heat Increment and Post‐Prandial Nitrogen Excretion of Penaeus setiferus, P. schmitti, P. duorarum, and P. notialis Postlarvae
Authors: Rosas Carlos , Sanchez Adolfo , Diaz Eugenio , Soto Luis A. , Gaxiola Gabriela , Brito Roberto
Published: April 2007

The calorigenic effect of feeding (apparent heat increment, AHI) and post‐prandial nitrogen excretion (PPNE) were measured in postlarval (PL 25–30) Penaeus setiferus, P. schmitti, P. duorarum and P. notialis fed a fixed ration of 3 mg/animal using purified diets with 40, 50, 60, or 65% protein. Both AHI and PPNE increased with increasing dietary protein. The contribution of PPNE to AHI varied from 6.1 to 94%, with lesser values for P. setiferus and greater ones for P. duorarum. Also, the AHI coefficient (percentage of ingested energy) increased with increasing dietary protein. The AHI and PPNE coefficients for the four shrimp species ranged from 0.3 to 6.5% and 0.02 to 5.04% of ingested energy, respectively. These results suggest close relationships among protein requirements, the capacity to use dietary proteins as a source of energy, and adaptation by different species to different types of food. The amount of energy used for production of ammonia is proposed as an adequate measure of the part played by dietary proteins in food cost.
A Comparison of Inert Markers Used to Estimate Protein Digestibility in the Leader Prawn Penaeus monodon
Authors: Deering M. J. , Hewitt D. R. , Sarac H. Z.
Published: April 2007

Abstract.— Acid insoluble ash, chromic oxide and ytterbium acetate were evaluated as digestibility markers in practical diets for leader prawns Penaeus monodon. Apparent protein digestibility coefficients ranged from 79.4% for chromic oxide to 82.6% for ytterbium acetate and were similar regardless of the marker used (P < 0.05). Coefficients of variation of protein digestibility coefficients ranged from 2.1% for ytterbium acetate to 4.9% for acid insoluble ash. Methods for selecting dietary markers for use are discussed.
Economic Evaluation of Commercial‐Scale, Saltwater Pond Production of Florida Red Tilapia in Puerto Rico
Authors: Head William D. , Zerbi Alfonso , Watanabe Wade O.
Published: April 2007

An economic analysis was performed of a proposed commercial‐scale 20‐ha saltwater pond culture operation for Florida red tilapia in Dorado, northern Puerto Rico. The analysis was based on actual cost and production data from a commercial‐scale hatchery, pilot‐scale grow‐out trials conducted in six 0.2‐ha saltwater (avg. = 22.7 ppt) ponds at the Dorado facility and on wholesale market prices ($4.96–5.18/kg) fetched by dressed‐out (gilled, gutted and scaled) product. The proposed 20‐ha growout facility is comprised of 25 0.8‐ha earthen ponds, each supplied with sea water, brackish well water, drainage and aeration, which account for 60.8% of the capital costs. Ponds are stocked with fingerlings (0.85 g avg. wt.) at a density of 3.0 fish/m2 (30,000/ha), and are harvested at 160 and 220 d, at an average weight of 545 g for a total yield of 11,445 kg/ha per crop. Imported feed ($0.55/kg), processing and distribution ($0.50/kg) and sex‐reversed fry ($0.11/fry) are the highest variable costs, accounting for 30.7%, 15.4% and 13.9%, respectively, of the total annual costs. Salaries and benefits, and depreciation represent the highest fixed costs, accounting for 8.4% and 5.5%, respectively, of the total annual costs. Under these conditions, a wholesale price of $4.55/kg results in a positive cash flow by year eight, and a breakeven price, internal rate of return (IRR), net present value (NPV) and discounted payback period (DPP) of $4.08/kg, 7.6%, ($235,717) and >10 yr, respectively, suggesting that the proposed 20‐ha operation is not economically feasible under these conditions. The proposed enterprise is marginally feasible if stocking density is increased to 3.5 fish/m2 while at 4.0 fish/m2 economic outlook is favorable. Costs can be lowered considerably by targeting production and market variables most sensitive to profitability indices, using locally‐prepared feeds, and vertically integrating hatchery and growout operations.
Phosphorus Availability of Common Feedstuffs to Channel Catfish Ictalurus punctatus as Measured by Weight Gain and Bone Mineralization1
Authors: Li Meng H. , Robinson Edwin H.
Published: April 2007

The efficacy of using weight gain and bone mineralization to estimate phosphorus availability from feed ingredients for channel catfish was investigated at the conclusion of a 12‐wk feeding trial. Juvenile channel catfish (initial weight = 7.8 g/fish) were fed one of seven test diets each containing phosphorus from a single source. All diets were isocaloric, isonitrogenous, and met all nutrient requirements of channel catfish except for phosphorus, which was assumed to be the factor limiting growth. Phosphorus was considered to be 90% available to fish fed the diet containing monosodium phosphate, but a relative value of 100 was assigned to this treatment for purposes of comparison. All other availability values were calculated relative to this value. Phosphorus availabilities (based on weight gain) for wheat middlings, cottonseed meal, and soybean meal were 38%, 43%, and 49%, respectively, which are in the range previously reported for channel catfish. Phosphorus availability values (based on weight gain) for dicalcium phosphate, menhaden fish meal, and meat and bone/blood meal were 82%, 75%, and 84%, respectively. These values were considerably higher (93–96%) than previously reported for catfish when based on bone ash or bone phosphorus. However, availability data based on weight gain for feedstuffs of animal origin generally agreed with phosphorus availability data reported for rainbow trout. Based on our data, mineral utilization by animals in general, and on known physiology of channel catfish, we suggest that weight gain may be a reliable indicator of phosphorus availability and that phosphorus availability values may be overestimated when base on bone mineralization.
Evaluation of First‐Feeding Regimens for Larval Nassau Grouper Epinephelus straitus and Preliminary, Pilot‐Scale Culture through Metamorphosis
Authors: Watanabe Wade O. , Ellis Simon C. , Ellis Eileen P. , Lopez Vicente Gracia , Bass Paul , Ginoza John , Moriwake Aaron
Published: April 2007

Two 10‐day hatchery experiments were conducted to evaluate s‐type (Hawaiian strain) and ss‐type (Thailand strain) rotifers Brachionus plicatilis and cryogenically preserved oyster Crassostrea gigas trochophores as first feeds for larval Nassau grouper Epinephelus striatus. Newly hatched grouper larvae were reared at densities of 11.2–20.8/L in 500‐L tanks at 36–38 ppt salinity, 25–26 C, and under a 11‐h light: 13‐h dark photoperiod. Beginning on day 2 posthatching (d2ph), prey were maintained at a density of 20 individuals/mL, while phytoplankton (Nanochloropsis oculata) was maintained at 500 × 103 cells/mL. In experiment 1, survival and growth were higher (P < 0.05) for fish fed small s‐type rotifers (mean lorica length = 117 μm; fish survival = 7.96%) selected by sieving than for fish fed non‐selected rotifers (mean lorica length = 161 μm; fish survival = 2.13%). These results demonstrated the advantage of small prey size and suggested that super‐small (ss‐type) rotifer strains would be beneficial. In experiment 2, three feeding regimens were compared: 1) ss‐type rotifers (mean lorica length = 147 μm); 2) oyster trochophores (mean diameter = 50 μm) gradually replaced by ss‐type rotifers from d5ph; and 3) a mixed‐prey teatment of 50% oyster trochophores and 50% ss‐type rotifers. Survival was higher (P < 0.05) for larvae fed mixed prey (15.6%) than for those fed rotifers (9.73%) or trochophores and rotifers in sequence (2.55%), which also showed the slowest growth. Oyster trochophores, although inadequate when used exclusively, enhanced survival when used in combination with rotifers, possibly by improving size selectivity and dietary quality. In a pilot‐scale trial, larvae were cultured through metamorphosis in two 33.8‐m3 outdoor tanks. Fertilized eggs were stocked at a density of 10 eggs/L and larvae were fed ss‐type rotifers from d2ph‐d20ph, newly hatched Artemia from d15ph‐d18ph, 1‐d‐old Artemia nauplii from d18ph‐d62ph. Survival on d62ph was 1.17%, with a total of 5,651 post‐metamorphic juveniles produced.
Triacylglycerol Digestion by the Leader Prawn Penaeus monodon
Authors: Deering M. J. , Hewitt D. R. , Brock I.
Published: April 2007

Abstract.— Midgut gland extracts from leader prawn Penaeus monodon were evaluated for lipase activity and positional specificity using triolein as a substrate. Lipase activity of aqueous and acetone midgut gland extracts was screened using a mammalian serum lipase test kit and triolein/agar emulsion clearing. Using the clearing method lipase activity was identified in both aqueous and acetone extracts. However, no lipase activity was detected using the serum lipase test kit. In vitro hydrolysis of triolein by midgut gland lipase at pH 8.0 produced 1,2‐diacylglycerol and free fatty acid as the sole digestion products indicating specificity for the 1‐position of triacylglycerol. The specifcity of lipases from Penaeus monodon for the primary position of triacylglycerol is similar to that of manmalian pancreatic lipase and lipases from Homarus americanus and most fish.
Initial Disease Report of Streptococcus iniae Infection in Hybrid Striped (Sunshine) Bass and Successful Therapeutic Intervention with the Fluoroquinolone Antibacterial Enrofloxacin
Authors: Stoffregen D. A. , Backman S. C. , Perham R. E. , Bowser P. R. , Babish J. G.
Published: April 2007

Streptococcal infection (Streptococcus iniae) was diagnosed sequentially in two tanks of hybrid striped bass Morone saxatilis male ×M. chrysops female (Sunshine bass) grown in a commercial freshwater recirculation facility in western Massachusetts. The pathogen was isolated in the laboratory, biochemically and morphologically characterized, and antibacterial sensitivities determined. Streptococcus iniae‐induced lesions in the Sunshine bass were character at the gross and histopathological levels. Initial treatment with oxytetracycline was unsuccessful. Based on sensitivity results, enrofloxacin‐medicated feed was dosed at 10 mg/kg body weight for 10 d, while a subsequent trial was conducted at 5 mg/kg body weight for 10 d. Mortality of fish subsided promptly following initiation of enrofloxacin therapy, yielding a final mortality in the initial tank of 10.83% (control tank 55.5%) and in the second tank of 16.97% (control tank 39.8%). Tissue enrofloxacin residues, detected via a microbiologic bioassay, revealed greater quantities and longer duration of residues in various tissues from the 5‐mg as compared to the 10‐mg trial, potentially the result of adverse feed palatability. Enrofloxacin appears to have excellent potential as an antibacterial agent for treating susceptible bacterial diseases of Sunshine bass.
Acclimation and Propagation of the Abalone Haliotis tuberculata in a Land‐Based Culture System in Israel
Authors: Shpigel M. , Marshall A. , Lupatsch I. , Mercer J. P. , Neori A.
Published: April 2007

Abstract.— The European abalone Haliotis tuberculata, a valuable macroalgivore, was introduced and acclimated for culture in a land‐based facility at Eilat, Israel, on the Red Sea (Gulf of Aqaba). Large quantities of high‐protein seaweed (Ulva lactuca) are produced there in biofilters used in fish mariculture. Although high water temperatures (25–27 C) inhibited summer growth, and in spite of the high salinity (41 ± 1 ppt). four groups of abalone of different sizes grew more in 1 yr than reported in their natural habitat. This fast growth is attributed to the long period (8 mo, from fall to spring) in which temperatures in Eilat waters are within the optimal range for this species, and to the high protein content of the seaweed. Winter timing of maximal growth as well as reproduction in Eilat was reversed compared with Europe, where they occur in summer. Gametogenesis began in December, and the gonads in most broodstock were spent by May. Haliotis tuberculata appears to have excellent potential for intensive mariculture in Israel.
Survival and Growth of Red Drum Sciaenops ocellatus in Saline Groundwaters of West Texas, USA
Authors: Forsberg James A. , Dorsett Paul W. , Neill William H.
Published: April 2007

Abstract.— West Texas saline groundwaters were assessed as potential media for culturing red drum, Sciaenops ocellatus. In 30‐d bioassays with juvenile red drum (0.4–3.0 g), highest survival was 85% in a 5‐ppt (parts per thousand = g/L) salinity, high‐sulfate (1,723 mg/L SO4‐2), high‐calcium (427 mg/L Ca±2) groundwater from a windmill catchment pond in Pecos County. The lowest survival was 0% in a 35‐ppt saline groundwater from a gravel pit, also in Pecos County. In complementary bioassays of low‐salinity (<5 ppt) groundwaters from the same region, calcium chloride (CaCl2) addition to a 3‐ppt. Reeves County ground‐water low in Ca±2 resulted in the greatest increase in survival (0–93). It was unclear whether the beneficial effect of CaCl2 was a result of increasing Ca±2 concentration (36–336 mg/L), increasing Cl‐ concentration (639–1,296 mg/L). or both. The concentration of total dissolved solids (“salinity”) appears to be the single most important consideration in estimating the red drum aquaculture potential of a groundwater, with the optimum salinity being 5–15 ppt. Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), and selenium (Se) tended to be higher in west Texas groundwaters than in typical U. S. surface waters. However, based on current maximum tolerable daily intake recommendations, red drum cultured for 30 d in west Texas groundwaters contained whole‐body As, Cd, Cr, Hg, Pb, and Se concentrations that would not pose a substantial health risk to adult human consumers.
Species and Size‐Related Trends in Asexual Propagation of Commercially Important Species of Tropical Sea Cucumbers (Holothuroidea)
Authors: Reichenbach Norman , Nishar Yoosuf , Saeed Ahamed
Published: April 2007

Abstract.— Juveniles of four species of tropical sea cucumbers of moderate to high commercial value were studied to determine their potential for being propagated asexually by evaluating their survival and regeneration times after being forced to undergo transverse fission. The four species were Holothuria fuscogilva.H. nobilis, Actinopyga mauritiana, and Stichopus variegatus. Rubber bands placed midbody on the sea cucumbers provided an effective yet simple technique to induce fission. Posterior parts of animals had similar or higher survivorship and shorter regeneration times relative to the anterior parts. Combining this information with that collected earlier on adults indicated that smaller animals (both anterior and posterior parts) had higher survivorship (up to 100%) and shorter regeneration times (as fast as 41 d) relative to adult animals of the same species. Using percent weight retained after processing into beche‐de‐mer, a rough measure of body wall thickness, and size of the animal relative to the adult weight, a multiple regression equation was calculated to predict percent survival and regeneration times for both anterior and posterior parts. The equation illustrated that small, thin‐walled species would have the highest survivorship and shortest regeneration times. As the percent weight retained increased, as would be the case with more thick‐walled species, and as the animal approached the adult weight, survivorship declined and the regeneration time increased.
Comparisons of Uptake and Depuration of 2‐Methylisoborneol in Male, Female, Juvenile, and 3MC‐induced Channel Catfish Ictalurus punctatus
Authors: Perkins Everett J. , Schlenk Daniel
Published: April 2007

The occurrence of off‐flavors in farm‐raised channel catfish is a major burden to the catfish culture industry, causing millions of dollars worth of market‐ready fish to be rejected each year. Off‐flavors are believed to be the result of exposure and subsequent accumulation of certain volatile microbial metabolites such as 2‐methylisoborneol. In this study, the uptake and elimination of [14C]‐2‐methylisoborneol equivalents were examined in juvenile and mature channel catfish. The described method is presented as a simple and inexpensive procedure for comparing treatment effects on off‐flavor elimination rates. In addition, the effects of the cytochrome P4501A inducing agent 3‐methylcholanthrene on 2‐methylisoborneol depuration was studied in juvenile fish. Uptake was determined during a 24–h static exposure to waterborne 2‐methylisoborneol (7.6 ± 3.7 μg/L). Uptake equilibrium had been established in all groups by 12 h, with total uptake higher in juvenile fish. Depuration rates were not different between untreated groups (t½ a = 12.r122.4 h; t½β= 91.3–143.7 h); however, the depuration half‐lives for 3‐methylcholanthrene treated juveniles were significantly longer than those of controls.
Improved Utilization of Pond Carrying Capacity by Increasing Initial Stocking Rates and Subsequent Stock Division1
Authors: Terhune Jeffery S. , Schwedler Thomas E. , Collier John A.
Published: April 2007

Fingerling channel catfish Ictaturus punctarus were stocked into eight 0.04‐ha ponds at 12,500 fishlha (treatment 1) and 50,000 fish/ha (treatment 2) with four ponds per treatment. At the end of of phase I (59 d) 50% of the fish were removed from each of the ponds in treatment 2 and divided equally into two ponds, forming treatment 3 (eight ponds at a density of 12,500 fish/ha). The remaining fish in treatment 2 (25,000 fish/ha) were maintained in the original ponds until the end of phase II (36 d). At this time, the fish were removed and equally divided at a density of 12,500 fish/ha into separate ponds. These ponds were continued to be denoted as treatment 2. All fish were grown for a total of 188 d. Production characteristics between treatments were compared at phases and at the end of the 188 d. There was no significant difference in feed conversion ratios due to treatment. The individual weights of the fish were higher in treatment I, but the difference occurred only in phase I. Size variabilities in treatments 2 and 3 were also higher than in treatment 1, which may cause a decrease in the percentage of marketable fish. Although there were some adverse effects due to the initial high stocking densities, overall pond production was higher in treatments 2 and 3. Treatment 2 had a daily net production of 49.9 ± 3.43 kg/ha and treatment 3 had 44.6 ± 3.81 kg/ha per d, compared to treatment 1 with only 32.4 ± 1.06 kg/ha per d (mean ± SD).
Hormone Induced Spawning of Summer Flounder Paralichthys dentatus
Authors: Berlinsky David L. , William King V , Hodson Ronald G. , Sullivan Craig V.
Published: April 2007

During their first year in captivity, summer flounder Paralicthys denratus were induced to spawn with gonadotropin releasing hormone analogue (GnRHa) implants, injected carp pituitary extract (CPE) or human chorionic gonadotropin (hCG) injections. The percentage of fertile eggs was greatest (69%) in CPE‐treated females. CPE, but not GnRHa or hCG, was capable of stimulating oocyte growth (increased follicle diameter during vitellogenesis) followed by ovulation. Fish with maximum ovarian follicle diameters between 180 and 435 μm at the initiation of CPE injections produced the greatest percentage of fertile eggs. For most females, fertilization rate was greatest for the first batch of eggs ovulated. The mean fertilization rate for the first spawn of CPE‐treated fish was 42% compared with 14% for the second spawn from the same fish. Fish with maximum initial follicle diameters of 585 40 μm that were implanted with GnRHa ovulated the greatest number of eggs, but fertility was low and variable. Approximately 35% of females injected with hCG ovulated a limited number of eggs, but only one hCG‐treated female produced fertile eggs. Only a limited number of spermiating males were available for spawning trials. Hormone treatments used on females were ineffective for inducing or maintaining spermiation in male summer flounder.
Tolerance of Snakehead Channa striatus to Ammonia at Different pH
Authors: Qin Jianguang , Fast Arlo W. , Kai Ashley T.
Published: April 2007

Tolerance of snakehead Channa striatus to ammonia was tested at three pH levels (8.0, 9.0. and 10.0) in experimental tanks. At pH 8.0, ammonia LC50 estimates for snakehead at 24, 48, 72, and 96 h were >205.7, >203.5, 152.6, and 107.3 mg total ammonianitrogen (TAN)/L (or >10.3, >10.2, 7.6, and 5.4 mg NH3‐N/L), respectively. At pH 9.0, ammonia LC50 estimates at 24, 48, 72, and 96 h were >52.4, 62.8, 56.1, 43.4 mg TAN/L (or >18.0, 21.6, 19.3, and 14.9 mg NH3‐N/L), respectively. At pH 10.0, ammonia LC50 estimates at 24, 48, 72, and 96 h were 25.7, 21.6, 20.3, and 18.7 mg TAN/L (or 21.6, 18.1, 17.1, and 15.7 mg NH3‐N/L). respectively. Our data indicate that the tolerance of snakehead to ammonia was associated with pH. Thus, we recommend that snakehead should not be subjected to prolonged exposures of NH3‐N concentration more than 0.54 ma at pH 8.0, more than 1.49 mg/L at pH 9.0, or more than 1.57 mg/L at pH 10.0.
Effect of Acclimation Temperature and TemperatureChanges on Molting and Survival of Ablated and Non‐ablated Crayfish Orconectes virihs
Authors: Twibell Ronald G. , Wilson Keith A. , Brown Paul B.
Published: April 2007

The effect of acclimation temperatures for producing soft‐shell crayfish, and changes upward from acclimation temperature, were evaluated in crayfish Orconectes virilis subjected to either hemilateral or bilateral eyestalk ablation. In each experiment, 60 juvenile O. virilis were reared for 21 d at temperatures ranging from 20 C to 30 C. Equal numbers of male and female crayfish ranging in weight from 5.0 g to 16.0 g were used in each study. In the first three experiments, crayfish were acclimated and maintained at a constant temperature. In the remaining experiments, crayfish were subjected to a step‐wise increase in temperature of either 5 or 10 C. Molting was highest in crayfish acclimated to 25 C prior to experimentation at 25 C (experiment 2) and in crayfish acclimated to 14 C prior to experimentation at 20 C (experiment 4). Total molts during these two experiments were 51 (85.0%) and 56 (93.3%), respectively. Bilateral eyestalk ablation resulted in significant reductions in the intermolt period in experiments 1 (acclimation temperature 20 C, experimental temperature 20 C), 3 (acclimation temperature 30 C, experimental temperature 30 C) and 6 (acclimation temperature 15 C, experimental temperature 25 C), while hemilateral eyestalk ablation had no effect on molting when compared to control (non‐ablated) crayfish. Bilateral eyestalk ablation resulted in a significant reduction in survival in experiments 5 (acclimation temperature 20 C, experimental temperature 25 C) and 6 (acclimation temperature 15 C, experimental temperature 25 C). Significantly more females molted in one experiment (acclimation temperature 20 C, experimental temperature 25 C), but not in any others. The results of these studies demonstrate that bilateral eyestalk ablation and water temperatures are effective methods of inducing molting in crayfish.
Offspring Growth in a Diallel Crossbreeding with Three Strains of Nile Tilapia Oreochromis niloticus
Authors: Marengoni Nilton G. , Onoue Yoshio , Oyama Tetsuo
Published: April 2007

Abstract— A complete diallel crossing of three strains, Stirling, Korean and Local, was used to evaluate heterosis of intraspecific crossbreeding on early growth of Nile tilapia Oreochromis niloticus. All possible F‐1 hybrid offspring were obtained and their growth rates to 90 d were compared. The specific heterosis for F‐1 hybrids in Stirling × Korean, Stirling × Local and Korean × Local crosses were 7.61, 5.63 and 7.70 for weight, and 0.47, 0.26 and 0.55 for length, respectively. The purebred Stirling strain showed better growth than the other two strains (P < 0.05). When growth of F‐1 hybrids was compared between sexes, males grew more rapidly than females (P < 0.05). However, no differences were observed in growth of male or female between hybrid groups. Purebred males in the Stirling strain were slightly heavier than those in the Korean and Local strains, and Local × Stirling, Korean × Local and Local × Korean crosses. However, in purebred females Stirling was superior to Korean, but not the Local strain and all F‐1 hybrid crosses. Implications to choose the appropriate strains for developing a breeding program of tilapia are also discussed.
Winter Culture of Yellowleg Shrimp Penaeus californiensis in Aerated Ponds with Low Water Exchange
Authors: Martinez‐Cordova Luis R. , Porchas‐Cornejo Marco A. , Villarreal‐Colmenares Humberto , Calderon‐Perez J. Antonio
Published: April 2007

Abstract— This study was conducted in the semiarid region of Bahia Kino, Sonora, Northwestern Mexico to determine the feasibility of farming yellowleg shrimp Penaeus californiensis during the winter season in ponds with less than 5% daily water exchange and aeration. Four aeration rates (0, 6, 12, and 24 h/d) were used in the study. Mean growth rates ranged from 0.41 to 0.53 g/wk with the highest growth rate in ponds with 12 h of aeration (P× 0.05). Survival ranged from 50 to 52% and did not differ among treatments. Shrimp yield ranged from 1,012 to 1,208 kg/ha, with the highest yields from ponds with 6 and 12 h of aeration (P× 0.05). Feed conversion ratios ranged from 2.3 to 2.8, with lower values in ponds with 12 and 6 h of aeration (P× 0.05). Results suggest that winter culture of yellowleg shrimp is possible and that 6 h of aeration is sufficient to maintain good water quality conditions.
Streptococcus iniae Infection of Tilapia Oreochromis niloticus in a Recirculation Production Facility
Authors: Bowser P. R. , Wooster G. A. , Getchell R. G. , Timmons M. B.
Published: April 2007

Abstract— Streptococcus iniae was isolated from moribund pure strain Nile tilapia Oreochromis niloticus in a water recirculation aquaculture facility. The extent of the infection was determined in a number of separate culture systems at the facility. A pilot study was also conducted to gain information on potential stressors that may play a role in spread of the infection within such a water reuse facility. The conditions employed in the pilot stress test did not have any apparent impact on spread of S. iniae infection to fish in additional tanks within the facility.
Hemolymph Metabolic Variables in Response to Experimental Manipulation Stress and Serotonin Injection in Penaeus vannamei
Authors: Racotta Ilie S. , Palacios Elena
Published: April 2007

Abstract— The effects of serotonin (5‐HT) and the stress of repeated sampling on Penaeus vannamei hemolymph levels of glucose, lactate, triacylglycerol, cholesterol, and total protein were examined. For this purpose, a baseline hemolymph sample was taken and then shrimp were injected with 5‐HT (50 μg/shrimp) or saline after which repeated individual samples were taken at 30, 60, and 120 min. Glucose levels tripled in both saline‐ and serotonin‐treated shrimp when compared to baseline values, without any difference between both groups. In contrast, lactate level rose significantly only in the 5‐HT group. The levels of this metabolite were significantly higher than in the salineinjection group for all time points. Triacylglycerol decreased in both groups and no substantial differences were observed in cholesterol and protein levels. The results indicate that repeated sampling stress produces strong hyperglycemia and that 5‐HT does not produce an additional increase in glucose levels. However. this monoamine strongly increased lactate levels, a response that can be distinguished from stress and probably attributed to glycolysis.
The Effects of Fertilization and Water Management on Growth and Production of Nile Tilapia in Deep Ponds During the Dry Season
Authors: Diana James S. , Lin C. Kwei
Published: April 2007

Abstract— Fertilization guidelines developed for shallow ponds (1 m) with controlled depths were tested in deeper (2.5 m) ponds to determine effectiveness of these guidelines for culture of Nile tilapia Oreochromis niloticus. Twelve ponds of 2.5‐m depth were used in four treatments: (A) weekly fertilization with water addition; (B) weekly fertilization without water addition; (C) one early fertilization without water addition; and (D) fertilization frequency dependent on nutrient concentrations, without water addition. Sex‐reversed Nile tilapia were stocked at 2 fish/m2 with an initial weight of 15 g, and harvested after 234 d. Depth of water declined from 2.4 m to 1.6 m over the experiment in ponds without water addition. Fish growth rate was significantly higher in treatments A and B (0.86 g/d), than in other treatments, as was yield (3,830 kg/ha). Treatment C was lowest in growth (0.086 g/d) and yield (168 kg/ha), with treatment D intermediate. Fish growth rates and yields were strongly correlated to manure input (R2= 0.89 and 0.94, respectively), and residuals were not correlated to any physical or chemical variables. Growth and yield in these deep ponds were somewhat lower than those in previous experiments for shallow ponds with regular water inputs. However, stagnant ponds did not accumulate nutrients and metabolites at rates higher than ponds with controlled water depths.
Optimizing the Concentration of Gamma‐Aminobutyric Acid (GABA) for Inducing Larval Metamorphosis in the Red Abalone Haliotis rufescens (Mollusca: Gastropoda)
Authors: Searcy‐Bernal Ricardo , Anguiano‐Beltrán Casandra
Published: April 2007

Abstract— The induction of larval metamorphosis is a critical step in abalone Haliotis spp. culture. Recently, gamma‐aminobutyric acid (GABA) has been used as an inducer by an increasing number of commercial hatcheries, because of its higher efficiency over other settlement methods. The conventional GABA concentration used is 1.0 micromolar as suggested by controlled laboratory experiments. However, poor results are occasionally reported in hatcheries, probably because the bacterial load in commercial systems degrade the inducer to levels below the required threshold. To cope with this problem, GABA concentration might be increased within safe limits to compensate for potential bacterial degradation, but information to adequately support this alternative is missing. This contribution describes two experiments on this issue with red abalone. H. rufescens larvae which suggest that GABA concentration could be increased at least 100% without causing the detrimental effects on metamorphosis induction or postlarval fitness reported for higher toxic levels. The impact of this result on abalone seed production is discussed.
Effects of Rotifer and Artemia Fatty‐Acid Enrichment on Survival, Growth and Pigmentation of Summer Flounder Paralichthys dentatus Larvae
Authors: Baker Edward P. , Alves David , Bengtson David A.
Published: April 2007

Abstract— Enrichment of live food for marine fish larvae with highly unsaturated fatty acids (HUFA) has been shown to improve survival, growth and stress resistance in many species and to decrease pigmentation abnormalities in flatfish. In order to aid the developing summer flounder industry, we conducted an experiment in which summer flounder larvae were fed diets differing in HUFA composition to determine whether enrichment with a commercially available product would increase survival and growth and reduce the incidence of abnormal pigmentation. We also examined whether growing unenriched rotifers on different species of algae would affect the survival, growth and pigmentation of the flounder larvae to which they were fed. Growth of summer flounder larvae was significantly better when they were fed HUFA‐enriched Mtifers and Artemia rather than unenriched and, among the unenriched treatments, was significantly better when the larvae were fed rotifers raised on Isochrysis galbana rather than on Tetraselmis suecica. The percentage of larvae that failed to complete metamorphosis during the experiment was significantly higher in the unenriched treatments than in the enriched treatments. Neither survival nor percentage of individuals with pigmentation abnormalities were significantly different among the treatments.
Performance of Domesticated Striped Bass Morone saxatilis, Palmetto Bass and Backcross Hybrid Striped Bass (Sunshine Bass ♀× Striped Bass ♂) Raised in a Tank Culture System
Authors: Jenkins Wallace E. , Heyward Louis D. , Smith Theodore I. J.
Published: April 2007

Abstract— Grow‐out performance of striped bass Morone saxatilis, palmetto bass (M. saxatilis ♀×M. chrysops ♂) and backcross hybrids [sunshine bass ♀(M. chtysops ♀×M. saxatilis ♂) × M. saxatilis♂] was examined in a two‐part study. During part I fish (mean weight = 20.1 g) were stocked at a density of 56 fish/m3 in 1.8‐m3 cylindrical fiberglass tanks connected to a central biological filter. Fish were fed a 38% protein trout ration daily and the study duration was 273 d. At harvest, no differences (P > 0.05) in mean weight or feed conversion were detected among the fish types. However, there were differences in specific growth, with the striped bass having a significantly higher growth rate than the palmetto bass and the backcross hybrids being intermediate. The condition factor (K) for striped bass was also significantly lower (1.2) than that recorded for either of the other two groups. In addition, survival of striped bass (91%) was significantly higher than that of backcross hybrids (74%), while survival of palmetto bass (87%) was intermediate. The survival of backcross hybrids was adversely impacted by an infestation of the dinoflagellate Amyloodinium sp. During part II stocking density in each tank was reduced to 19 fish/m3. The study lasted 104 d. At harvest, no differences were detected in weight, survival, or feed conversion. However, there were significant differences in specific growth, length and K. Striped bass and backcross hybrids gained weight faster than palmetto bass. Length and K were inversely related with all groups being significantly different. Striped bass had the largest TL and the lowest K while, palmetto bass were the shortest with the highest K.
Substitution of Canola Meal for Soybean Meal in Diets for Channel Catfish Ictalurus punctatus
Authors: Lim C. , Klesius P. H. , Higgs D. A.
Published: April 2007

Abstract Canola meal was used in channel catfish Ictalurus punctatus diets at levels of 0, 15.4, 30.8, 46.2 and 61.6%, by progressively replacing (on an equal nitrogen basis) 0, 25, 50, 75, or 100% of solvent‐extracted soybean meal in the control diet. The feeds were formulated to contain approximately 29% crude protein and 2,650 kcal of digestible energy/kg on an air‐dry basis. Each diet was fed to juvenile channel catfish to satiation twice daily for 10 wk. Fish fed the diets containing the two lowest levels of canola meal (15.4 and 30.8%) had similar weight gains, feed intakes, feed utilization efficiencies, and percent survivals relative to the group fed the control diet. Weight gains and feed intakes declined significantly as the dietary levels of canola meal were increased to 46.2% or higher, probably because of reductions in diet palatability and some impairment of feed utilization due to the presence of increased levels of antinutritional factors, particularly glucosinolates. Whole body percentages for moisture and crude protein were unaffected by the dietary treatments. Body ash contents, however, were lowest for fish fed the control diets but were essentially the same for fish fed the other diets. Fish fed the diet containing 30.8% canola meal had lowest body fat content but this effect may not have been diet related. Values for red blood cell concentration, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were not affected by dietary canola meal level, but hematocrit was higher (although not always significant) for fish fed the control diet. The results of this study suggest that canola meal can comprise about 31% of the diet of channel catfish by replacing half of the amount of soybean meal used in the control diet without adversely affecting growth or any other aspect of performance.
Fatty Acid Composition of Muscle, Liver, and Depot Fat of Wild and Cultured Common Snapping Turtles Chelydra serpentina
Authors: Mayeaux Maxwell H. , Reigh Robert C. , Culley Dudley D.
Published: April 2007

Abstract This study was conducted to compare the fatty acid composition of muscle, liver, and depot fat of common snapping turtles Chelydra serpentina from the wild with those of captive common snapping turtles fed a diet of known fatty acid composition. Total lipid from each tissue was separated by thin‐layer chromotography, methylated, and analyzed by gas chromatography/mass spectrometry. The fatty acid composition of total lipid, polar lipid, and nonpolar lipid in muscle and depot fat of wild and captive turtles exhibited greater variability than liver polar lipid. Cultured turtles contained significantly lower levels of linolenic and arachidonic acids in liver polar lipid than wild turtles. Total n‐9 fatty acids were significantly higher in whole‐lipid and nonpolar fractions of muscle, liver, and depot fat of cultured turtles indicating de novo synthesis. Total polyunsaturated fatty acids were significantly lower in total lipid of muscle tissue from cultured turtles. Total polyunsaturated fatty acids were significantly lower in both depot fat and liver nonpolar lipid of cultured turtles, but did not differ (P > 0.05) in the polar lipid fractions of cultured and wild turtles.
Multiple Induced Spawnings of the Indian Catfish Heteropneustes fossilis (Bloch) within a Prolonged Spawning Season
Authors: Alok Deoraj , Krishnan T. , Talwar G. P. , Garg Lalit C.
Published: April 2007

Abstract Singhi, the Indian catfish Heteropneustes fossilis, attained gonadal maturity repeatedly in a single spawning cycle by photothermal treatment. After the first spawning, maintenance at 30 C and 14 h light/10 h dark for 3 wk induced recruitment of the next batch of mature oocytes for subsequent spawnings. The number of eggs released declined with each spawning. However, fertilizability of the eggs was maintained until the fifth spawning. Mature fish were induced to spawn by D‐Lys6 salmon gonadotropin‐releasing hormone agonist administration. The dose of salmon gonadotropin‐releasing hormone agonist for the second and subsequent spawnings was determined to be 25‐fold less compared to the dose administered for the first spawning. Fish released the maximum number of eggs upon induction when they were maintained continuously at 30 C and 14 h light/10 h dark for 6 wk. The result obtained in the present study points to a possibility of obtaining multiple spawnings from those species of farmed fish which spawn once a year.
Growth Rate Responses of Five Commercial Strains of Gracilaria (Rhodophyta, Gracilariales) to Temperature and Light
Authors: Macchiavello Juan , De Paula ÉDison J. , Oliveira Eurico C.
Published: April 2007

Abstract Growth rate responses of five strains of four economically important species of Gracilaria from South America, Africa and Asia were studied under several temperature and light combinations, in experiments lasting from one to four weeks. Gracilaria tenuistipitata var. liui from the People's Republic of China was the most eurythermic of the species studied, growing at temperatures from 13.5 to 33.1 C, and all photon flux densities (15–91 μmol‐photons/m2 per sec). Gracilaria caudata from Brazil did not survive at 13.5 C and G. chilensis did not survive at 30.2 C, while G. gracilis from Namibia and Argentina survived up to 33.1 C. No strain survived at 35.8 C or higher. In general, there was a trend to an increase in growth rate with temperature, but this varied with the irradiance and the duration of the experiments. There was a clear interaction between temperature and photon flux density, and the duration of the experimental period interfered significantly in the growth responses. All strains tested, including G. chilensis from Chile and G. gracilis from Argentina and Namibia, could be cultivated under ambient conditions of temperature and photon flux density on the southern coast of Brazil.
Water Quality and Phytoplankton Communities in Intensive Shrimp Culture Ponds in Kung Krabaen Bay, Eastern Thailand
Authors: And Siri Tookwinas , Songsangjinda Putth
Published: April 2007

Water quality and phytoplankton communities were studied in 20 intensive shrimp culture ponds and in the inlet and drainage canals at Kung Krabaen Bay, Eastern Thailand during the first shrimp crop of 1992. The grow‐out ponds were categorized into two groups: low stocking density (<60 PL/m2) and high stocking density (>60 PL/m2). The results showed that there were no significant differences in water quality between the two stocking density groups. Phytoplankton collected using a 60‐μm mesh net consisted of 79 genera with concentrations ranging from 1,822 to 72,527 cells/L from the first month up to the time of shrimp harvesting. Water quality deteriorated in high and low stocking density shrimp ponds, which had an influence on abundance and diversity of net phytoplankton communities. Biochemical oxygen demand and ammonia‐nitrogen were most closely related to abundance of net phytoplankton communities during the shrimp grow‐out period. Salinity, temperature, and dissolved oxygen appeared to play an important role in phytoplankton community variation in inlet and drainage canals. Phytoplankton community structure in drainage canals showed more variation than in ponds. The management implications of the results and recommendations for further studies are also considered.
Recovery and Viability of Edwardsiella ictaluri from Great Blue Herons Ardea herodias Fed E. ictaluri‐Infected Channel Catfish Ictalurus punctatus Fingerlings
Authors: Waterstrat Paul R. , Dorr Brian , Glahn, and James F. , Tobin Mark E.
Published: April 2007

Feeding activities of great blue herons Ardea herodias in catfish ponds during outbreaks of enteric septicemia of catfish have been implicated as a mechanism for the transmission of the disease from infected to uninfected ponds. Although Edwardsiella ictaluri, the causative agent, has been identified in gastrointestinal tracts of great blue herons, the role of these birds as a vector of E. ictaluri is not well documented. The potential of these birds to contaminate catfish ponds with E. ictaluri was investigated by feeding captive herons over a 4‐d period with catfish fingerlings injected intraperitoneally with live E. ictaluri. Daily fecal samples, throat and rectal swabs, and feather samples were collected, cultured and examined for E. ictaluri using both a selective media and a monoclonal indirect fluorescent antibody test specific for E. ictaluri. Gastrointestinal tracts sampled at the conclusion of the feeding trial were similarly examined. While E. ictaluri was detected using the indirect fluorescent antibody test, no viable E. ictaluri was cultured from either feces, gastrointestinal tracts or feathers. Growth of E. ictaluri was not observed at 40 C, the rectal temperature observed in captive great blue herons. Prior incubation at 40 C suppressed the growth of E. ictaluri at 24 C, an optimal temperature for growth of this bacterium. These results indicate that great blue herons appear to play little or no role in the transmission of E. ictaluri among catfish ponds.
Biochemical Oxygen Demand in Channel Catfish Ictalurus punctatus Pond Waters
Authors: Boyd Claude E. , Gross Amit
Published: April 2007

A study of the biochemical oxygen demand (BOD) of waters from ten channel catfish ponds at Auburn, Alabama, revealed that the 5‐d BOD (BOD5) seldom exceeded 8 mg/L and that the ultimate BOD (BODu) was usually less than 30 mg/L. Water samples from catfish ponds usually needed to be diluted only 2 or 3 times to permit BOD5 measurements, and nitrification occurred even during a 5‐d incubation period. Catfish pond waters were not extremely high in ammonia nitrogen concentration, and ammonia nitrogen introduced in the ammonium chloride‐enriched dilution water caused an appreciable increase in BOD of some samples. Plankton respiration is a major component of carbonaceous BOD (CBOD) in catfish pond waters. Thus, the BOD is not expressed as rapidly during 5‐d incubations as in typical waste‐water. The ultimate BOD (BODu) would be a good measurement of oxygen demand for catfish pond effluents, but it is difficult to measure. Data from this study suggest that BODu can be estimated from BOD5, but the correlation is not strong (R2= 0.62). An alternative is to develop a short‐term BOD measurement specifically for effluents from channel catfish and other aquaculture ponds. This study suggests that a 10‐d BOD conducted without nitrification inhibition or addition of ammonia nitrogen in dilution water might be a better alternative to standard BOD5 or BODu measurements normally used in wastewater evaluation.