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Increased understanding of the factors that influence the frequency of purchase of catfish (Ictalurus punctatus) by U.S. households would provide guidance for catfish marketing programs. A household survey was conducted to analyze consumer preferences and consumption trends of U.S. farm-raised catfish in Birmingham, Memphis, Chicago, Jackson (MS), New Orleans, Baton Rouge, Little Rock, Oklahoma City, Dallas, Houston, and San Antonio. An ordered probit model was developed to examine the variables influencing frequency of catfish purchase. Household respondents in all cities except Jackson, New Orleans, Oklahoma City, and San Antonio were found to be more frequent buyers of catfish products. Respondents who preferred fresh catfish had a greater likelihood of frequent catfish purchase while buyers of frozen catfish were less likely to purchase catfish frequently. Method of preparation and serving had no influence on catfish purchase frequency. Buyers purchasing from supermarket outlets had a higher probability of being more frequent buyers of catfish products than those who purchase from other market outlets. Product origin labels and vacuum-sealed packaging influenced the frequency of catfish purchase. Caucasians and African Americans were found to be more frequent buyers of catfish products while Hispanics were found to be significantly less frequent buyers of catfish products. Married couples had a greater likelihood of purchasing catfish more frequently than unmarried couples. Age of the respondents as well as number of household members had no significant effect on frequency of catfish purchase. The results from this study support the importance of country of origin labeling, supplying high-quality fresh products, and alternative packaging to enhance sales of U.S. farm-raised catfish in supermarkets. [ABSTRACT FROM AUTHOR]

The article discusses findings of a study which evaluated and compared the relative toxicity of malathion and malaoxon in blue catfish Ictalurus furcatus. Acetylcholinesterase is a critical body enzyme inhibited by malathion, and this capability then requires that malathion should first be converted to malaoxon to become an active anticholinesterase agent. The findings of the research suggested that malaoxon is more toxic than the parent compound malathion, and several confirmed bioindicators of malathion exposure in blue catfish include acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine activities.

Channel catfish Ictalurus punctatus do not feed well at low temperatures. It is generally thought that a diet containing fish meal enhances feed palatability at low temperatures since fish meal is highly palatable to fish. There is a lack of information on the effects of fish meal levels on the growth performance of channel catfish reared at low temperatures. Therefore, a study was conducted in a recirculating system to examine the effects of fish meal levels on the feed consumption, weight gain, and feed efficiency of juvenile channel catfish reared at various temperatures. Fish with an initial weight of 9.6 ± 0.1 g were stocked in 23-L clear polycarbonate tanks maintained at approximately 17, 21, or 27 °C. The fish were fed with diets containing 0, 4, or 8% menhaden Brevoortia spp. fish meal for 9 weeks. There was a significant interaction between water temperature and fish meal level with respect to weight gain. At 27°C, fish fed diets containing 4% and 8% fish meal gained significantly more weight than fish fed the all-plant-protein diet. However, the level of fish meal had no significant effect on the weight gain of fish at 17°C or 21°C. This suggests that the olfactory and gustatory responses of channel catfish to fish meal (up to 8% in the diet) may not be as sensitive at low temperatures as at optimum temperatures. The results also indicate that more than 4% fish meal in the diet is not beneficial for the optimum growth and feed efficiency of channel catfish fingerlings raised at 27°C. [ABSTRACT FROM AUTHOR]

This review reports on the various presentations as well as new revealed data relating to the epileptic disorder defined as childhood epilepsy with occipital paroxysms characterized by occipital epileptic discharges recorded by electroencephalography. The initial rigidly delineated subtypes by the International League Against Epilepsy included the following: (a) Panayiotopoulos syndrome—early-onset seizure disorder presenting with prolonged infrequent, nocturnal autonomic seizures, accompanied by eye deviation and ictal vomiting. (b) Gastaut syndrome—late-onset type presenting with short diurnal frequent seizures and visual ictal manifestations along with migrainous headaches. A high percentage of children present, however, with mixed clinical phenomena making it difficult to comply with the rigidly segregated syndromes reported by several authorities including our recent report on 28 children of whom 14 showed mixed phenomena. Therefore, childhood epilepsy with occipital paroxysm should be suspected at any age presenting with nocturnal vomiting, autonomic impairment, focal motor fits with head deviation, migraine headaches, and/or visual perturbations. [ABSTRACT FROM AUTHOR]

Sixty-eight families of USDA303 channel catfish Ictalurus punctatus were evaluated for growth performance for 30 d. The fastest- and slowest-growing channel catfishfamilies were further evaluated to examine the hypothesis that genes or gene products associated with the growth regulatory and stress axes can be used to describe differences in growth performance. Research examined mRNA levels of genes involved in the growth hormone-insulin-like growth factor (GH-IGF) network in fast- (family A) and slow-growing (family H) USDA303 catfish. Fish (59.0 ± 2.4 g) were fed for 7 weeks, weighed, and had tissues for RNA extraction. The remaining fish were subjected to an acute 10-min dewatering stress. Insulin-like growth factor-II mRNA was higher in the muscle of fast-growing fish, while the levels of IGF-I receptor (IGF-IR) and IGF-I1 receptor (IGF-II) were similar. Muscle IGF-IIR mRNA was two-fold higher than muscle IGF-IR mRNA. There were no differences in liver and muscle IGF-I and GH receptor mRNA or pituitary GH mRNA between the fast- and slow-growing fish. Fast-growing fish consumed 135% more feed than slow-growing fish, though the abundances of ghrelin mRNA in the gut and neuropeptide Y mRNA in the hypothalamus were similar. Cortisol levels were negatively correlated to weight gain. These results suggest that the variation in growth between fast- and slow-growing USDA303 catfish is explained, in part, by the variation in the GH-IGF and stress axes. The relationship between cortisol and weight gain warrants further investigation for possible exploitation in our selective breeding program. [ABSTRACT FROM AUTHOR]

The channel catfish Ictalurus punctatus is an important aquaculture species in the United States and has received considerable research attention in efforts to improve production. Three traits of importance to the U.S. farm-raised channel catfish industry are disease resistance, growth, and reproduction. While many factors affect these three traits, a fish's response to stress can have a substantial impact on production attributes. Understanding the relationships between the stress response and components of that response, such as plasma cortisol concentration, is important to the development of better management and breeding practices to maximize production. Although much of the data regarding the fish physiological consequences of stress and elevated plasma cortisol has been collected from studies of salmonids, recent advances have been made toward understanding these relationships in channel catfish. The present review synthesizes the research conducted over the past several years regarding the effects of stress and cortisol on disease susceptibility, growth, metabolism, and reproduction of channel catfish in the context of how stress and cortisol affect economically important production traits for aquaculture. [ABSTRACT FROM AUTHOR]

Two practical diets that differed in cost based upon protein sources were evaluated as treatments relative to production and associated economics of the fingerling-stocker phase of culture for channel catfish Ictalurus punctatus. The commercially manufactured fingerling feeds contained approximately 35% crude protein and were fed to fingerling channel catfish (mean weight = 13.8 g; mean length = 12.2 cm, respectively) stocked into experimental earthen ponds (0.05 ha) at a density of 123,550 fish/ha. There were five replicates (ponds) per treatment. The fish were fed daily to satiation, unless some physical or biological factor warranted an abstention of one or more days. After 180 d, all ponds were harvested by seine and then completely drained. Mean individual harvest weight and length of fish fed the high-cost practical diet were significantly greater than those of fish fed the low-cost diet. Survival and feed conversion ratios were not significantly different between dietary treatment groups. The percentage of harvested fish exceeding 114 g, a size that escapes predation by cormorants Phalacrocorax spp., ranged from 47% to 56% for the low-cost treatment and from 72% to 77% for the high-cost treatment. Individual stocker production cost was US$0.217 for the low-cost dietary treatment and $0.258 for the high-cost treatment. Economic analyses were used to compare the three-phase (modular) production scheme (which incorporated the two diet-dependent fingerling-stocker management scenarios) with the traditional multiple-batch system (partial harvest and topping off). Total production costs for the three-phase system were $0.04-0.24 per kilogram less than those of the multiple-batch production system. Total cost of food fish production in the three-phase system ranged from $1.406 (low-cost diet) to $1.417 (high-cost diet) per kilogram. The fingerling-stocker phase offers a variety of management options to meet different production goals, and the three-phase system appears to be a cost-effective alternative management strategy for the farming of channel catfish. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate production management methods to improve overall survival of channel catfish, Ictalurus punctatus, fry to the fingerling stage by incorporating the use of a live, attenuated vaccine against Edwardsiella ictaluri and employing an extended hatchery phase. In this experiment, four treatments were used. In Treatment 1, 10-d posthatch (PH) fry were vaccinated and then directly stocked into earthen ponds. In Treatments 2 and 3, 10-d PH fry were sham-vaccinated (control) and vaccinated, respectively, kept in nursery tanks for 22 d, and then stocked into earthen ponds. Fry in Treatment 4 were sham-vaccinated at 10 d PH, kept in nursery tanks for 22 d, and then vaccinated prior to stocking into earthen ponds. Mean fingerling yield at harvest ranged from 4716 kg/ha in Treatment 1 to 8112 kg/ha in Treatment 4. Mean individual fish weight ranged from 38.8 g in Treatment 1 to 40.9 g in Treatment 4, and feed conversion ratios (FCR) ranged from 1.15 in Treatment 4 to 1.51 in Treatment 1. Mean survival ranged from 47.5% in Treatment 1 to 73.4% in Treatment 4. In specific comparisons to evaluate the nursery effect (Treatments 1 and 3), yield and overall survival were significantly different ( P < 0.05) between these two treatments. In specific comparisons to evaluate the effect of the use of the vaccine (Treatments 2, 3, and 4), overall survival was significantly different ( P < 0.05) between Treatment 2 (sham-vaccinated control with nursery phase) and Treatment 4 (vaccinated at 32 d PH with nursery phase). No significant differences ( P > 0.05) in yield, average weight, and FCR were observed between treatments. Results indicate that implementing an extended hatchery phase and vaccination strategy with older fry can improve overall survival of fingerling fish. [ABSTRACT FROM AUTHOR]

The article reports on results of a study of the complete structure, genomic organization and expression of channel catfish or Ictalurus punctatus, matrix metalloproteinase-9 gene (MMP-9). A description of the study design and method is presented. The study concluded that the MMP-9 transcript was constitutively expressed in restrictive CC tissues.

The effect of using a finishing diet containing menhaden fish oil on the fatty acid composition of fingerling channel catfish, Ictalurus punctatus, was evaluated in a 12-wk growth trial. Three isocaloric, isonitrogenous practical diets with three different sources of lipids (menhaden oil [MO], catfish oil [CO], or beef tallow [BT]) were formulated (35% crude protein). No differences in eicosapentaenoic acid, docosahexaenoic acid, or arachidonic acid were observed to occur in catfish fed MO or CO diets; however, these fatty acids were significantly lower in fish fed BT diet. No differences were observed for unsaturated fatty acid content in channel catfish fed a diet containing MO for 8 or 12 wk. In addition, no differences in production characteristics were observed to occur when catfish were fed diets containing CO, MO, or BT as the dietary lipid source, which indicates that BT, CO, and MO are equally effective as sources of energy. It is apparent from these results that CO may be successfully substituted for MO in formulated diets without adversely affecting n-3 highly unsaturated fatty acid content in channel catfish. [ABSTRACT FROM AUTHOR]

Currently, no flow regulations exist for the protection of riverine fishes in Missouri. Prerequisites for establishing flow guidelines are understanding what habitats are used by fishes at different times of the year and how much of that habitat will be available to each species under different discharge scenarios. We quantified microhabitat associations and selection for juvenile channel catfish Ictalurus punctatus, flathead catfish Pylodictis olivaris and stonecat Noturus flavus in a flow-regulated prairie river during summer (diurnal and nocturnal periods) and autumn (diurnal period) and then presented two-dimensional hydraulic modeling results from a previous study to determine how diel and seasonal microhabitat shifts might impact the availability of selected habitats at different flows. All ictalurid species exhibited seasonal and diel shifts in microhabitat selection. Selected habitat available would generally be maximized for each species between 10 m³/s and 30 m³/s which is greater than the current median discharge. Stonecats are most susceptible to dewatering during the diurnal summer period; however, the availability of selected habitat becomes flow limited (<10 m³/s) for all species during summer nocturnal and autumn periods because of changes in microhabitat selection during these periods. Channel catfish could be substantially impacted by extremely low flows during the summer nocturnal and autumn periods with no selected habitat available below 1 m³/s. Quantifying the amount of selected habitat that may be available under different discharge scenarios will aid managers in determining appropriate minimum flows for maintaining habitats for these species under a flow regime that continues to be partitioned to different stakeholder groups. [ABSTRACT FROM AUTHOR]

Cuphea meal is a new, alternative feedstuff that has potential as a sustainable, economical replacement for wheat, rice, and corn ingredients in channel catfish, Ictalurus punctatus, diets. Channel catfish fingerlings were fed a control diet containing wheat or two experimental diets containing 7.5% cuphea meal, or 12.5% cuphea meal for eight weeks to determine if cuphea meal could replace wheat products in catfish diets. Mean (±SE) weight gains were 317.8 ± 28.8 g, 407.0 ± 36.9 g, and 372.8 ± 29.8 g for fish fed the control diet, the 7.5% cuphea meal diet, and the 15% cuphea meal diet, respectively, and there were no significant differences (P < 0.05) among treatments. Mean (±SE) whole-body protein of fish fed the cuphea diets (13.3 ± 0.66 and 14.5 ± 0.21%) was significantly (P < 0.05) higher than that of fish fed the wheat diet (12.7 ± 0.44%). Cuphea meal enhanced body composition of juvenile channel catfish without affecting growth or survival. Therefore, cuphea meal is a promising candidate for replacement of wheat bran at the levels tested. INSET: Evaluation of Cuphea Meal as an Ingredient.... [ABSTRACT FROM AUTHOR]

Commercially produced, food-size channel catfish Ictalurus punctatus that were harvested using routine procedures had significant elevations in plasma cortisol, glucose, and lactate compared with preharvest fish captured from open ponds. Blood samples were taken from 10 fish in each of two treatments (liquid oxygen diffuser- and paddlewheel-aerated holding socks) and four sampling periods (before harvest, after socking, before loading, and before unloading) during each of 10 harvest events. Water column temperatures averaged approximately 27°C during the study. Ten fillet samples were taken from fish held overnight in paddlewheel- and liquid oxygen-aerated holding socks during some harvest events. Mean plasma cortisol levels averaged 3.02 ng/mL before harvest, 84.38 ng/mL immediately after socking, 135.22 ng/mL after 18 h in the sock (i.e., before loading onto the truck), and 128.54 ng/mL after 2-3 h on the truck (i.e., before unloading). Mean plasma glucose levels averaged 34.7 mg/dL before harvest, 95.41 mg/dL after socking, 134.53 mg/dL before loading, and 134.86 mg/dL before unloading. Mean plasma lactate levels averaged 2.43 mmol/L before harvest, 13.24 mmol/L after socking, 11.53 mmol/L before loading, and 7.88 mmol/L before unloading. These results should not be considered maximal until additional studies are conducted with average water temperatures at their highest. There were significant changes within treatment over 7 d of refrigerated storage for fillet pH, color, and drip loss; however, there were no consistent trends between treatments. Results indicate that routine capture and hauling procedures are stressful to commercially produced, food-size channel catfish under the examined conditions and that using liquid oxygen for aerating fish in holding socks does not significantly improve fillet quality or reduce stress levels. [ABSTRACT FROM AUTHOR]

Environmentally derived "off-flavors" such as earthy" and "musty" in cultured channel catfish Ictalurus punctatus are attributed to the presence of certain species of cyanobacteria (blue-green algae) in ponds. The musty off flavor is caused by absorption of the metabolite 2-methyl-isobomeol (MIB) into channel catfish flesh. Most channel catfish producers manage off-flavor episodes by the application of algicides; however, these algicides have high environmental persistence and broad-spectrum toxicity. Recent research has discovered several natural and natural-based quinones that are effective and selective in reducing the abundance of the MIB-producing cyanobacterium Planktothrix perornata. In this study, efficacy testing of one of these quinones, anthraquinone-59, in a channel catfish pond found that it is effective in reducing the abundance of P. perornata and subsequently lowering the MIB levels in channel catfish. [ABSTRACT FROM AUTHOR]

The article presents a study which discussed the reductions in susceptibility of channel catfish to enteric septicemia. According to the author, disease resistance normally has lower heritability than growth rate and other traits in most aquaculture species. Low heritability can slow down the progress of selective breeding. There is still a huge amount of variation in response to the challenge posed by the bacterium Edwardsiella ictaluri. The evidence presented here in this study suggests that resistance to enteric septicemia of catfish is heritable.

The peroxiredoxin 6 gene (Prdx6) of channel catfish, Ictalurus punctatus, has been cloned and characterized. The sequence of the channel catfish Prdx6 gene consists of 1,003 nucleotides. Analysis of the nucleotide sequence reveals one open reading frame and 55-bp 5′ and 276-bp 3′-untranslated regions. The open reading frame potentially encodes 223 amino acids with a calculated molecular mass of 24.6 kDa. The amino acid sequence of channel catfish Prdx6 had 85.2%, 77.7%, 74.1%, 73.7%, 73.7%, 73.7%, 73.2%, and 71.9% identity with that of zebrafish, chicken, human, mouse, Norway rat, pig, cow, and Xenopus laevis, respectively. Channel catfish Prdx6 had four cysteine residues. In addition to one conserved at Cys46, the Cys132 residue seems to be conserved among fish and frog. Channel catfish Prdx6 conserved two reactive motifs with peroxidase and phopholipase A2 activity. The channel catfish Prdx6 transcript was detected in all the tissues analyzed, suggesting the gene is constitutively expressed and is involved in protecting channel catfish tissues from oxidative damage. This result will not only provide information for further exploration of the role of Prdx6 in fish pathophysiology but also fill the gap in the evolutionary tree. [ABSTRACT FROM AUTHOR]

We compared the swimming performance of juvenile pond-cultured and wild-caught channel catfish Ictalurus punctatus using a fixed-velocity, time-to-fatigue protocol as a measure of overall fitness. Swimming performance of juvenile catfish from each source was determined at 10-cm/s intervals between speeds of 30 and 120 cm/s. The identified swimming performance categories included sustained speeds (swimming speeds without fatigue in times ≥200 min: aerobic metabolism); prolonged speeds (swimming speeds with fatigue in times ≥20 s but <200 min: mixed aerobic and anaerobic metabolism); and burst (swimming speeds with fatigue in times ≥20 s: anaerobic metabolism). The maximum sustained swimming speed (maximum speed without fatigue in times ≥200 min) was 40 cm/s for both pond-cultured and wild-caught juveniles. The maximum prolonged swimming speed (maximum speed with fatigue in times ≥200 min) was 90 and 100 cm/s for wild-caught and pond-cultured juvenile catfish, respectively. The swimming performance of pond-cultured and wild-caught juvenile catfish differed significantly only at 120 cm/s, which was a burst swimming speed for wild-caught juveniles and a prolonged swimming speed for pond-cultured juveniles. The burst swimming speed for pond-cultured juveniles was not determined but was estimated to be more than 120 cm/s. The total length, standard length, fork length, and condition factor of juvenile pond-cultured and wild-caught catfish were not significantly different. The reported swimming performance data provide important information on the overall fitness (e.g., ability to obtain prey and avoid predation) of juvenile pond-cultured and wild-caught catfish that will benefit fisheries managers considering the stocking of juvenile pond-cultured channel catfish in managed lakes and rivers as well as research scientists developing and evaluating improved strains of channel catfish for commercial production. [ABSTRACT FROM AUTHOR]

Traditional fecundity analysis, either as number of eggs per body weight of female or number of eggs per gram of egg mass, pay little attention to females that do not spawn. These fecundity variables contain a high proportion of zeroes either because of the absence of eggs or the inability to recover the eggs. Zero-inflated discrete generalized linear models are an alternative method that can be developed to take into account females that do not spawn. In this case study, we propose discrete generalized linear models that use specially constructed mixture models to handle the excess zeroes such as the zero-inflated Poisson and zero-inflated negative binomial models. These models have the advantage of modeling fecundity simultaneously with the probability of spawning. The results show that age was the most significant factor influencing the number of eggs per gram of egg mass, while period of spawning was the most significant factor influencing the number of eggs per female body weight. These were also the most important variables that significantly affected the probability of successful spawning. Model residual diagnostics show that zero-inflated models exhibit superior performance compared to the traditional models like analysis of covariance, Poisson regression, and negative binomial regression models. [ABSTRACT FROM AUTHOR]

Broodstock evaluations are often measured by variables such as spawning success, fecundity, fertilization and hatching rates, usually expressed as percentage values. Outcomes are generally analysed as continuous random variables, assuming that they follow a normal distribution. Ordinary linear regression models (e.g. analysis of variance) as well as χ2 analysis are typically applied. However, these models may not be the most appropriate as a number of test criteria may not be met. For example, spawning success outcomes are inherently discrete and non-negative data and hence their distribution is not likely to be normal. As these models may not be the most appropriate, a case study using logit analysis as an alternative method for the evaluation of this type of data is presented by considering the response as binary data (spawned versus did not spawn). An exact version of logit analysis was performed due to the sparseness of the data. The results demonstrate that appropriate statistical models provide better insight into the cause–effect relationships that exist between control variables and the dependent variable (likelihood of spawning in this case). As would be expected, each strain of fish responded somewhat differently to the test variables. Changing the protein level of the diet from 32% to 42% or increasing the feeding frequency from three to six times per week either did not influence spawning or negatively affected spawning respectively. Additionally, older fish performed better than younger fish and the early spawning period was better than the later spawning period, regardless of strain. These responses, however, were only detected using logit analysis, which is a more sensitive test and would thus be recommended for this type of data. [ABSTRACT FROM AUTHOR]

Abstract: Potential variation in reproductive performance as young broodfish among four selectively bred strains of channel catfish was evaluated by comparing profiles of plasma estradiol, testosterone, and vitellogenin, and activities of cathepsin D, L, and B in follicle-enclosed oocytes during vitellogenesis in 2- to 3-yr-old females. No differences among the four strains were detected for any of the parameters measured. Plasma steroid concentrations demonstrated temporal differences, with testosterone levels peaking in January and estradiol levels peaking in April. Monthly changes in circulating vitellogenin concentrations coincided with oocyte growth. Average oocyte size in May, the typical time of spawning, was smaller (1624 μm) than that considered normal for mature oocytes (approx. 3000 μm) in this species. Furthermore, only 9% of the females in this study spawned, and no significant correlations could be determined between the reproductive indices and spawning success. Activities of cathepsin D, L, and B were also similar between the four strains of catfish. Cathepsin L activity was highest in March, and cathepsin D activity was highest in March and May. Cathepsin B activity was generally lower than the activities of either cathepsin L or D, with the highest levels occurring in November, December, and March. This is the first report of cathepsin activities and their relationships to other reproductive parameters in channel catfish. [Copyright &y& Elsevier]

A closed, stirring respirometer was designed to agitate small egg mass samples of channel catfish Ictalurus punctatus while measuring oxygen consumption by the eggs. Egg mass samples ranging in size from 15 to 46 g were placed on a screen platform above a magnetic stir bar in the respirometer; the degree of agitation was controlled with a magnetic stir plate. Dissolved oxygen (DO) concentration and temperature were measured with a luminescent DO sensor and meter. The respirometer was used to determine routine metabolic rate and limiting oxygen concentration (the presumed hypometabolic transition zone) on egg mass samples front 10 different spawns at 0 to 5 d postfertilization. Routine metabolic rate increased from 4.8 ± 1.3 (0 d postfertilization) to 174.0 ± 7.8 mg O2·kg-1·h-1 (5 d postfertilization). The limiting oxygen concentration increased similarly up to 87.0% ± 2.7% (maximum individual value = 95.9%) air saturation by 5 d postfertilization. The respirometer described could not be used for sac fry, but it proved effective with clumped channel catfish eggs. Preliminary channel catfish hatchery management recommendations are to maintain DO concentrations in hatchery troughs at air saturation at least during the last day of egg development. [ABSTRACT FROM AUTHOR]

This study documents early out-of-season induced spawning of channel catfish Ictalurus punctatus. During the early spring (February–April) of 1999, 2000 and 2001, ponds containing (1) male and female channel catfish (mixed-sex ponds) or (2) male channel and blue catfish I. furcatus only, or female channel catfish only (single-sex ponds) were heated to 24–30°C to encourage gonadal maturation and spawning. Unheated ponds were stocked with males and females and were monitored during the duration of heating. When natural spawning occurred in the heated ponds, the fish were captured by seining and unspawned females were injected with 100 μg kg−1 of synthetic leutenizing hormone-releasing hormone. Injected females were either paired with males or held in communal all-female groups, and monitored for ovulation. Eggs were collected and fertilized with sperm of channel catfish or blue catfish. Females paired with males were induced to spawn 44 days (mixed-sex ponds) and 50 days (single-sex ponds) before natural spawning occurred in unheated ponds. Spawning latency (the time between injection and ovulation) and the percentage of neurulated embryos from eggs fertilized using channel catfish sperm was not different between spawning before the natural season ( P=0.68) and during the natural season in fish from mixed-sex ponds ( P=0.57). Females held in all-female groups produced eggs 34 days before the onset of spawning in unheated ponds. Spawning latency was not different between spawns before and during the natural season ( P=0.16), and the percentages of neurulated embryos from eggs fertilized with channel catfish sperm ( P=0.76) or blue catfish sperm ( P=0.77) before or during the natural season were not different. This study demonstrates the feasibility of conditioning of channel catfish females for early out-of-season induced spawning in the laboratory. [ABSTRACT FROM AUTHOR]

Channel catfish, Ictalurus punctatus, 88.4 ± 2.6 g/fish, were fed a basal diet amended with 4% of three processed menhaden, Brevoortia tyrannus, oils. These were compared with basal diets amended with 4% corn oil or 4% canola oil. Three replicate aquaria of nine fish each were fed assigned diets twice daily. At 6 wk, fish were group weighed, fillets were collected for sensory evaluation, fatty acid analysis by gas chromatography (GC). In a second study, catfish, 118.8 ± 3.2 g/fish, were stocked into fifteen 0.04-ha earthen ponds and fed once daily for 16 wk one of four diets containing 2 or 4% of either catfish offal oil or refined (RF) menhaden oil. At harvest, fillets were saved for sensory evaluation and fatty acid analysis. Results showed no significant ( P > 0.05) differences among treatments for aquarium study and pond study variables such as weight gain, fillet proximate analysis, or pond production. GC analysis showed that levels of omega-3 ( n-3) highly unsaturated fatty acids (HUFA) in fillet lipid were significantly ( P < 0.05) elevated for fish fed menhaden oil diets. Sensory evaluation revealed that fillets from fish fed RF menhaden oil had satisfactory flavor and could be a source of n-3 HUFA for humans. [ABSTRACT FROM AUTHOR]

Growth of sympatric populations of three important sport fish species: bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides and channel catfish Ictalurus punctatus, in 14 Illinois reservoirs was assessed in an attempt to relate size-specific growth to environmental conditions. Multiple regression relationships for most species and size classes explained a large percentage of the variation in growth. Growth of small bluegill (50 mm total length, LT) showed a strong negative relationship with bluegill catch per unit effort (cpue), per cent littoral area and pH. Large bluegill (150 mm LT) growth was negatively related to Daphnia spp. and benthic macroinvertebrate abundance and lake volume, and positively related to bluegill cpue. Growth of small (100 mm LT) and large (250 mm LT) largemouth bass was not well explained by any of the measured variables. Growth of both small (300 mm LT) and large (450 mm LT) channel catfish was strongly positively related to forage fishes and ichthyoplankton abundance, and per cent littoral area while negatively related to benthic macroinvertebrates. By identifying environmental conditions associated with increased growth rates, these models provide direction for managing fish populations and suggest testable hypotheses for future study of the complex interactions between environmental conditions and growth. [ABSTRACT FROM AUTHOR]

Behavioral observations have suggested that Channel Catfish, Ictalurus punctatus, spawn as monogamous pairs and that males alone provide subsequent care to the resulting embryos and fry. However, genetic monogamy is quite uncommon in fish and is not necessarily correctly predicted by apparent social interactions. Here we develop and employ seven microsatellite loci to address biological parentage and the genetic mating system in a natural population of I. punctatus. A total of 175 progeny and their respective attendant males were genotyped from five nests. Results indicate that each male had mated with only one female in his nest. Additionally, one nest contained a second group of full sibs unrelated to the attendant male and his mate who proved to be the biological parents of all other progeny within that nest. This instance probably represents either a case of nest piracy by the attendant male or perhaps our inadvertent sampling of progeny from two closely adjacent nests. In any event, our findings help confirm a rare suspected example of genetic monogamy in a fish species with uniparental offspring care. [ABSTRACT FROM AUTHOR]

Three experiments were conducted to evaluate the use of “finishing” diets in channel catfish, Ictalurus punctatus, production. Fingerling channel catfish weighing 107, 129, and 103 g for Experiments 1, 2, and 3, respectively were stocked in 0.04-ha earthen ponds at a rate of 14,820 fish per ha and grown to harvestable size in a single growing season. Four replicate ponds were used for each treatment. In Experiment 1, fish were fed either a 28%- or 32%-protein diet for the entire growing season (controls), or fed the 28%- and 32%-protein diets for part of the growing season and then switched to a 36%-protein “finishing” diet either 30 days or 60 days before harvest. In Experiment 2, fish were fed either a 24%- or 32%-protein diet for the entire growing season (controls), or fed a 24%-protein diet for part of the growing season and then switched to a 32%- or a 35%-protein “finishing” diet for either 30 days or 45 days before harvest. In Experiment 3, fish were fed either a 28%-protein diet for the entire growing season or a 28%-protein diet for part of the growing season, and then switched to a 35%-protein “finishing” diet for either 30, 45, or 60 days before harvest. The data show that a 24%-protein diet is sufficient for maximum growth and feed efficiency of catfish but processing yield is reduced. Further, it appears that feeding fish a 24%-protein diet for most of the growing season and then changing to a 32%- or 35%-protein “finishing” diet for 30 days before harvest, improves carcass yield. Fillet yield also appeared to be improved, but the improvement was slight. The data did not show that “finishing” fish fed a 28%-protein diet on higher protein diets was beneficial in improving processing yield. However, evaluating pooled data from across all of our previous studies, there does appear to be about a 0.4% to 0.5% decrease in processing yield of fish fed a 28%-protein diet. Presently, we do not recommend the use of “finishing” diets, because available data are not consistent, and their benefit is questionable. Also, because of various factors (such as off flavor), one cannot predict with certainty when fish will be harvested. [ABSTRACT FROM PUBLISHER]

Three experiments were conducted to evaluate the use of “finishing” diets in channel catfish, Ictalurus punctatus, production. Fingerling channel catfish weighing 107, 129, and 103 g for Experiments 1, 2, and 3, respectively were stocked in 0.04-ha earthen ponds at a rate of 14,820 fish per ha and grown to harvestable size in a single growing season. Four replicate ponds were used for each treatment. In Experiment 1, fish were fed either a 28%- or 32%-protein diet for the entire growing season (controls), or fed the 28%- and 32%-protein diets for part of the growing season and then switched to a 36%-protein “finishing” diet either 30 days or 60 days before harvest. In Experiment 2, fish were fed either a 24%- or 32%-protein diet for the entire growing season (controls), or fed a 24%-protein diet for part of the growing season and then switched to a 32%- or a 35%-protein “finishing” diet for either 30 days or 45 days before harvest. In Experiment 3, fish were fed either a 28%-protein diet for the entire growing season or a 28%-protein diet for part of the growing season, and then switched to a 35%-protein “finishing” diet for either 30, 45, or 60 days before harvest. The data show that a 24%-protein diet is sufficient for maximum growth and feed efficiency of catfish but processing yield is reduced. Further, it appears that feeding fish a 24%-protein diet for most of the growing season and then changing to a 32%- or 35%-protein “finishing” diet for 30 days before harvest, improves carcass yield. Fillet yield also appeared to be improved, but the improvement was slight. The data did not show that “finishing” fish fed a 28%-protein diet on higher protein diets was beneficial in improving processing yield. However, evaluating pooled data from across all of our previous studies, there does appear to be about a 0.4% to 0.5% decrease in processing yield of fish fed a 28%-protein diet. Presently, we do not recommend the use of “finishing” diets, because available data are not consistent, and their benefit is questionable. Also, because of various factors (such as off flavor), one cannot predict with certainty when fish will be harvested. [ABSTRACT FROM PUBLISHER]

Soybean meal, the major protein source used in commercial feeds for channel catfish Ictalurus punctatus, contains natural phytoestrogens known as isoflavones, many of which have been found to be endocrine disruptors. This study investigated whether genistein (an isoflavone) in a soybean-based diet would increase plasma vitellogenin (Vtg) concentrations and whether it would compete with estradiol E2; for binding sites on adult channel catfish hepatic estrogen receptors (ERs). Three-year-old channel catfish males and females were fed a casein-based diet (control) or a soybean-based diet. The genistein concentrations were 93.2 ng/g and 415,800 ng/g in the control and soybean diets, respectively. The binding specificity of the ERs was assessed by binding-affinity studies. In order of decreasing binding affinity, ethinylestradiol > E2; > genistein > testosterone, demonstrating that the hepatic ERs in channel catfish bind estrogens and genistein more than androgens. No significant differences in affinity (Kd) were observed for hepatic ERs in male or female catfish fed the soybean diet compared with those fed the control diet. Significant increases in binding capacity (Bmax;) for males fed the soybean diet (158 ± 15 fmol/mg protein) were evident compared with males fed the control diet (73 ± 4 fmol/mg protein). Genistein competed with [³H]E2; for hepatic ERs in both the male and female channel catfish. The relative binding affinities in male ERs were higher (2.72) than those in female ERs (1.17) for genistein. Because diets of farm-raised channel catfish are routinely composed of high quantities of soybean meal, the findings that genistein stimulates Vtg production in male channel catfish and binds to the ERs in both male and female channel catfish suggest that dietary genistein could alter production traits. However, further research to elucidate the effects of genistein on catfish reproduction is necessary to determine the impact of this phytoestrogen on catfish physiology. [ABSTRACT FROM AUTHOR]

Channel catfish, Ictalurus punctatus (Rafinesque 1818), and sunshine bass, female white bass Morone chrysops (Rafinesque 1820) X male striped bass M. saxatilis (Walbaum 1792), juveniles (10 and 12 g, respectively) were exposed to copper sulfate (CuSO4)in a series of static toxicity tests to observe species sensitivity. The water used in this study was 18.9°C filtered well water with initial pH of 8.71, and total alkalinity and total hardness of 224 and 110 mg/L, respectively. Estimates of mean 96-hour median lethal concentration (LC50) values were 1.75 mg/L Cu (6.89 mg/L CuSO4) for channel catfish and 0.85 mg/ L Cu (3.35 mg/L CuSO4) ) for sunshine bass; LC50 values were calculated using nominal CuSO4) concentrations. These values differed significantly. This study demonstrates that sunshine bass juveniles are less tolerant of CuSO4 than channel catfish fingerlings when exposed concurrently in waters from the same source. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the dynamical scenarios of transitions between normal and paroxysmal state in epilepsy. We assume that some epileptic neural network are bistable i.e., they feature two operational states, ictal and interictal that co-exist. The transitions between these two states may occur according to a Poisson process, a random walk process or as a result of deterministic time—dependent mechanisms. We analyze data from animal models of absence epilepsy, human epilepsies and in vitro models. The distributions of durations of ictal and interictal epochs are fitted with a gamma distribution. On the basis of qualitative features of the fits, we identify the dynamical processes that may have generated the underlying data. The analysis showed that the following hold. 1) The dynamics of ictal epochs differ from those of interictal states. 2) Seizure initiation can be accounted for by a random walk process while seizure termination is often mediated by deterministic mechanisms. 3) In certain cases, the transitions between ictal and interictal states can be modeled by a Poisson process operating in a bistable network. These results imply that exact prediction of seizure occurrence is not possible but termination of an ictal state by appropriate counter stimulation might be feasible. [ABSTRACT FROM AUTHOR]

The effectiveness of a pool-and-weir fish pass in the regulated river Laarse Beek (Belgium) was assessed for bullhead ( Cottus gobio), perch ( Perca fluviatilis) and roach ( Rutilus rutilus) from August 2002 to April 2003. Fish were caught by electrofishing downstream, within and upstream of the fish pass. They were marked with visible implant elastomer tags and released downstream of the fish pass. Our results suggest that the fish pass is ineffective for the bullhead because none of the 1270 tagged bullheads were recaptured in the upstream study area. Passage failure most likely resulted from excessive water velocities in the fish pass. On the contrary, 8% of the tagged perch and 29% of the tagged roach were recaptured in the upstream study area. Several management strategies are proposed to allow free upstream passage of the endangered bullhead at the fish pass under study. [ABSTRACT FROM AUTHOR]