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Channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus) are two economically important freshwater aquaculture species in the United States, with channel catfish contributing to nearly half of the country's aquaculture production. While differences in economic traits such as growth rate and disease resistance have been noted, the extent of transcriptomic variance across various tissues between these species remains largely unexplored. The hybridization of female channel catfish with male blue catfish has led to the development of superior hybrid catfish breeds that exhibit enhanced growth rates and improved disease resistance, which dominate more than half of the total US catfish production. While hybrid catfish have significant growth advantages in earthen ponds, channel catfish were reported to grow faster in tank culture environments. In this study, we confirmed channel fish's superiority in growth over blue catfish in 60-L tanks at 10.8 months of age (30.3 g and 11.6 g in this study, respectively; p < 0.001). In addition, we conducted RNA sequencing experiments and established transcriptomic resources for the heart, liver, intestine, mucus, and muscle of both species. The number of expressed genes varied across tissues, ranging from 5,036 in the muscle to over 20,000 in the mucus. Gene Ontology analysis has revealed the functional specificity of differentially expressed genes within their respective tissues, with significant pathway enrichment in metabolic pathways, immune activity, and stress responses. Noteworthy tissue-specific marker genes, including lrrc10, fabp2, myog, pth1a, hspa9, cyp21a2, agt, and ngtb, have been identified. This transcriptome resource is poised to support future investigations into the molecular mechanisms underlying environment-dependent heterosis and advance genetic breeding efforts of hybrid catfish. [ABSTRACT FROM AUTHOR]

In the United States, catfish are primarily farmed in earthen ponds, resulting in an aquatic environment influenced both by management practices and natural ecological processes. Profiling pond water microbiota can be useful for understanding what conditions may lead to microbial communities associated with production issues and could inform management practices. The aim of this study was to identify appropriate methods for bacterial community profiling of catfish pond water with nanopore sequencing of the 16S rRNA gene. To this end, two forward primers, two reverse primers, and three different polymerase chain reaction (PCR) cycle numbers were tested on a mock community consisting of aquaculture‐relevant bacteria. The optimized protocol was applied to water samples obtained from three experimental catfish ponds sampled in May, June, August, and September 2020. Applying these methods to pond samples allowed for the identification of 1488 genera, primarily within four dominating phyla: Actinobacteriota, Bacteroidota, Cyanobacteria, and Firmicutes. High variation was observed between individual ponds and sampling timepoints; only 18 of the 1488 genera were found in relative abundances ≥1% in all ponds from at least one sampling point. Despite this variation, consistent results could be observed. Samples obtained from the month of September had the highest number of observed genera, and samples from June had the lowest. Overall, these data demonstrated individual ponds represent distinct microcosms composed of unique bacterial communities, although this pond effect was secondary to the influence of sampling month on pond community composition. [ABSTRACT FROM AUTHOR]

Objective: The Yaqui Catfish Ictalurus pricei, a species that is endemic to the southwestern United States and west‐central Chihuahua and Sonora, Mexico, is extinct in the United States and extremely endangered in Mexico due to habitat loss and hybridization with nonnative Channel Catfish I. punctatus. To re‐establish populations in the United States, a binational program consisting of broodstock collection, fish propagation, stocking, and poststocking monitoring is necessary. This programmatic approach is encapsulated within a Conservation Propagation and Stocking Program (CPSP), which documents important recovery actions, such as genetic management, fish culture, stocking, and poststocking assessments. The focus of our work is to identify the optimal stocking strategy for Yaqui Catfish, thereby informing the framework of a CPSP for the species' recovery. Methods: Our strategy involved simulating population growth using an age‐structured simulation model with varying stocking contribution rates, stocking densities, and stocking frequencies and incorporating these biological data with economic information within a utility function to quantify stocking costs. Result: The optimal strategy requires releasing Yaqui Catfish at a density of 200 fish/ha every 5 years. This strategy excludes natural recruitment because historically, stocked Yaqui Catfish inhabited waters that were either too small or devoid of habitat to induce natural spawning. However, if larger waters or waters having appropriate habitats (e.g., interstitial spaces) are also stocked, it should increase natural recruitment, thereby (1) enabling populations to become self‐sustaining and (2) drastically reducing the reliance on hatcheries for stocking and salvage of declining populations. Conclusion: Our results provide important stocking recommendations within a CPSP, emphasizing the need to build a broodstock before genetically pure Yaqui Catfish disappear. The successful implementation of the optimal stocking strategy requires multiple locations for stocking fish and is contingent on strengthening binational partnerships. This approach fills an important void in Yaqui Catfish reestablishment, helping to prime the successful recovery of this species. Impact statementThe Yaqui Catfish, once native to regions of the United States and Mexico, faces near extinction due to habitat degradation and nonnative hybridization. A binational Conservation Propagation and Stocking Program offers a promising solution, suggesting for the release of 200 fish per hectare every 5 years in the United States. The initiatives success, however, hinges on using multiple stocking locations in Mexico and bolstering binational collaboration. [ABSTRACT FROM AUTHOR]

Bolbophorus damnificus is a digenetic trematode causing significant economic losses within the United States commercial catfish industry. The indirect life cycle is complex, requiring piscivorous birds, aquatic snails, and fish to complete. With federal protections on many piscivorous birds and no FDA‐approved therapeutic treatment for trematode infections in fish, management within the catfish industry is primarily limited to controlling the snail host. Planorbella trivolvis and Biomphalaria havanensis are snails commonly found in commercial catfish ponds and known to transmit B. damnificus. This study evaluated a low‐cost snail trap prototype for monitoring populations of these snails in efforts to better inform treatment regimes. Snail traps were deployed into ponds on a commercial catfish farm and checked weekly throughout the production season. All snails were identified and counted to evaluate trap efficacy. Traps captured significantly more snails in foodfish ponds than in fingerling ponds; however, this trend was not present in monthly box samples. B. havanensis was rarely collected and was only found consistently within one pond, while P. trivolvis was routinely collected from all ponds, although abundance varied widely among ponds. Snail traps could be a useful, low‐cost method to monitor snail populations within ponds and better inform control treatments. [ABSTRACT FROM AUTHOR]

Catfish ranked 8th among seafoods consumed per capita in the United States (U.S.) in 2019. As a major catfish product, catfish fillets are often chilled or frozen for storage after filleting and trimming operations. When they are removed from storage for further processing, manual interference is required to separate and flatten all the catfish fillets that otherwise could agglomerate together. This is necessary for further processing operations such as breading and individual quick-freezing. Because of the shortage of labor force and rising labor costs, there is an urgent need to reduce labor dependence by developing automated singulation methods for catfish fillets manufacturing, to enhance the profitability of the U.S. catfish industry. This study presents a novel singulation system that enables separating catfish fillets by utilizing water buoyancy and underwater streams. Several operation parameters have been investigated and optimized to achieve better singulation performance and production rate. The continuous production mode with operation rules is defined to keep the total amount being processed in an appropriate range for maximizing the singulation effect and production rate. This study will be beneficial for developing more effective next-generation singulation technologies for catfish and other fish species. [ABSTRACT FROM AUTHOR]

Catfish farming is the largest aquaculture industry in the United States and an important economic driver in several southeastern states. Edwardsiella piscicida is a Gram‐negative pathogen associated with significant losses in catfish aquaculture. Several Gram‐negative bacteria use the BasS/BasR two‐component system (TCS) to adapt to environmental changes and the host immune system. Currently, the role of BasS/BasR system in E. piscicida virulence has not been characterized. In the present study, two mutants were constructed by deleting the basS and basR genes in E. piscicida strain C07‐087. Both mutant strains were characterized for virulence and immune protection in catfish hosts. The EpΔbasS and EpΔbasR mutants were more sensitive to acidic environments and produced significantly less biofilm than the wild‐type. In vivo studies in channel catfish (Ictalurus punctatus) revealed that both EpΔbasS and EpΔbasR were significantly attenuated compared with the parental wild‐type (3.57% and 4.17% vs. 49.16% mortalities). Moreover, there was significant protection, 95.2% and 92.3% relative percent survival (RPS), in channel catfish vaccinated with EpΔbasS and EpΔbasR against E. piscicida infection. Protection in channel catfish was associated with a significantly higher level of antibodies and upregulation of immune‐related genes (IgM, IL‐8 and CD8‐α) in channel catfish vaccinated with EpΔbasS and EpΔbasR strains compared with non‐vaccinated fish. Hybrid catfish (channel catfish ♀ × blue catfish ♂) challenges demonstrated long‐term protection against subsequent challenges with E. piscicida and E. ictaluri. Our findings demonstrate BasS and BasR contribute to acid tolerance and biofilm formation, which may facilitate E. piscicida survival in harsh environments. Further, our results show that EpΔbasS and EpΔbasR mutants were safe and protective in channel catfish fingerlings, although their virulence and efficacy in hybrid catfish warrant further investigation. These data provide information regarding an important mechanism of E. piscicida virulence, and it suggests EpΔbasS and EpΔbasR strains have potential as vaccines against this emergent catfish pathogen. [ABSTRACT FROM AUTHOR]

The catfish industry is integral to the economy of the southern United States contributing >70% of the total U. S. finfish production. Intensive catfish production systems are more vulnerable to infectious disease outbreaks resulting in significant economic losses. Viruses are a major concern especially in the hatchery and nursery phases of catfish rearing. These infectious agents require host cell machineries to replicate. The ability to propagate fish viruses in vitro using cell cultures is imperative in advancing virus research and facilitating disease management strategies. Several viruses show host‐ or even tissue‐specificity. Scarcity of host‐specific fish cell lines forces researchers to rely on general cell lines that might not be conducive for the replication of some viruses, thus hindering their isolation, identification, and characterization. The ictalurid cell line (channel catfish ovary [CCO‐ATCC® CRL‐2772]) previously available from cell repository (ATCC) has recently been reported as cross‐contaminated by brown bullhead (BB) cells. Lack of host‐specific cell cultures and contamination issues necessitated initiation of cell cultures from the fin tissues of hybrid catfish (♀ channel catfish × ♂ blue catfish). A combination approach involving tissue explantation and enzymatic digestion methods were used to develop catfish fin cell cultures. These cultures were passaged over 100 times and transitioned into an established cell line. The hybrid catfish fin (HCF) cell line was characterized, growth conditions optimized, species of origin molecularly authenticated, and the susceptibility to fish viruses evaluated. This catfish cell line could serve as an efficient tool for virus studies, antiviral agent screening, and vaccine development benefitting catfish aquaculture. [ABSTRACT FROM AUTHOR]

"Musty" off‐flavor in pond‐raised Channel Catfish Ictalurus punctatus can result in an unpalatable and unmarketable product for catfish farmers in the southern United States. Certain species of cyanobacteria (blue‐green algae) in the catfish ponds produce 2‐methylisoborneol (MIB), which accumulates in the Channel Catfish flesh and causes musty off‐flavor. One management approach available to United States catfish farmers is the application of algicides to ponds to reduce the abundance of noxious cyanobacteria. Diuron is one approved algicide to specifically manage MIB‐related off‐flavor caused by the common cyanobacterium Planktothrix perornata f. attenuata. In this study, three commercial ponds determined in the early summer to contain musty off‐flavor Channel Catfish were monitored over approximately 2 months to determine the impact and pattern of weekly diuron applications on the abundance of P. perornata, chlorophytes (green algae), MIB concentrations in the pond water, and flavor characteristics of the sampled Channel Catfish collected during the treatment period. After several diuron applications to each pond, the abundance of P. perornata and MIB concentrations in pond water decreased dramatically. Channel Catfish in each pond were determined to be "on‐flavor" approximately 2 months after the initial diuron application. This study demonstrates that diuron applied via label‐specified treatment protocols provides catfish farmers with a practical management approach for P. perornata and subsequent MIB‐related off‐flavor. [ABSTRACT FROM AUTHOR]

The bacterium Edwardsiella piscicida causes significant losses in global aquaculture, particularly channel (Ictalurus punctatus) × blue (I. furcatus) hybrid catfish cultured in the south‐eastern United States. Emergence of E. piscicida in hybrid catfish is worrisome given current industry trends towards increased hybrid production. The project objectives were to assess intraspecific genetic variability of E. piscicida isolates recovered from diseased channel and hybrid catfish in Mississippi; and determine virulence associations among genetic variants. Repetitive extragenic palindromic sequence‐based PCR (rep‐PCR) using ERIC I and II primers was used to screen 158 E. piscicida diagnostic case isolates. A subsample of 39 E. piscicida isolates, representing predominant rep‐PCR profiles, was further characterized using BOX and (GTG)5 rep‐PCR primers, virulence gene assessment and multilocus sequence analysis (MLSA) targeting housekeeping genes gyrb, pgi and phoU. The MLSA provided greater resolution than rep‐PCR, revealing 5 discrete phylogroups that correlated similarly with virulence gene profiles. Virulence assessments using E. piscicida representatives from each MLSA group resulted in 14‐day cumulative mortality ranging from 22% to 54% and 63 to 72% in channel and hybrid fingerlings, respectively. Across all phylogroups, mortality was higher in hybrid catfish (p <.05), supporting previous work indicating E. piscicida is an emerging threat to hybrid catfish aquaculture in the south‐eastern United States. [ABSTRACT FROM AUTHOR]

The U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) conducts surveillance of metallic elements in U.S. meat, poultry, and Siluriformes fish samples collected immediately postmortem as part of its National Residue Program (NRP). From 2017 to 2022, 13,966 samples were analyzed under the NRP. The Federal Emergency Response Network (FERN) Cooperative Agreement Program (CAP) tests meat, poultry, and Siluriformes fish products collected at retail in the United States for metals. From 2018 to 2022, 2,902 samples were analyzed by FERN CAP laboratories. Meat and poultry samples collected by FSIS show that most metals were not detected at all or were detected infrequently. Meat is a rich source of iron and zinc, and iron was detected in 22% (1,255/5,623) and zinc was detected in 48% (2,742/5,676) of meat and poultry samples, respectively. The percentage of samples testing positive for manganese, molybdenum, lead, and cadmium were higher in the FERN CAP retail samples than in FSIS samples. Expected human exposure from average levels of lead and cadmium found in meat and poultry was compared to toxicological reference values and was not found to exceed these values. Detections of arsenic and mercury were found more often in Siluriformes fish samples (2017-2022) than in terrestrial animals. Trace amounts of arsenic and mercury were detected in 8% and 4% of Siluriformes samples, respectively, but were not detected at levels that raise concern. On the whole, both the FSIS and FERN CAP datasets provide reassuring evidence of the safety of the FSIS-regulated food supply with regard to the studied elements., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

Edwardsiella piscicida is a Gram‐negative facultative intracellular bacterium causing edwardsiellosis in catfish, the largest aquaculture industry in the United States. A safe and effective vaccine is an urgent need to avoid economic losses associated with E. piscicida outbreaks. PhoP/PhoQ is a two‐component signal transduction system (TCS) that plays an important role in bacterial pathogenesis through sense and response to environmental and host stress signals. This study aimed to explore the contribution of PhoQ/PhoP in E. piscicida virulence and develop live attenuated vaccines against E. piscicida infection in channel catfish (Ictalurus punctatus) and hybrid catfish (channel catfish ♀ × blue catfish (I. furcatus) ♂). In the current study, two in‐frame deletion mutants were constructed by deleting phoP (ETAC_09785) and phoQ (ETAC_09790) genes in E. piscicida strain C07‐087, and the virulence and protection efficacy of the constructed strains were evaluated in catfish following intraperitoneal injection. Both EpΔphoP and EpΔphoQ strains had a delayed adaptation to oxidative stress (0.2% H2O2) compared to E. piscicida wild type. The EpΔphoP and EpΔphoQ mutants produced significantly less biofilm compared to wild‐type E. piscicida. Notably, EpΔphoP and EpΔphoQ mutants were significantly attenuated in channel catfish compared with wild‐type E. piscicida (6.63% and 4.17% versus 49.16% mortalities), and channel catfish vaccinated with EpΔphoP and EpΔphoQ were significantly protected (95.65% and 97.92% survival) against E. piscicida infection at 21 days post‐vaccination. In hybrid catfish, EpΔphoP was significantly more attenuated than EpΔphoQ, but EpΔphoQ provided significantly better protection than EpΔphoP. EpΔphoP and EpΔphoQ strains both induced specific antibodies in channel catfish against E. piscicida at 14 and 21 days post‐vaccination. This result indicated that EpΔphoP and EpΔphoQ mutants were safe and protective in channel catfish fingerlings, while EpΔphoP was safe in hybrid catfish. Our findings show that PhoP and PhoQ are required for adaptation to oxidative stress and biofilm formation and may help E. piscicida face tough environmental challenges; thus, functional PhoP and PhoQ are critical for a successful infection. [ABSTRACT FROM AUTHOR]

Intraspecies variability in sperm quality is common among aquaculture species, thus necessitating an urgent need to establish reliable molecular biomarkers to screen for males with high-quality sperm. The channel catfish (Ictalurus punctatus) ♀ × blue catfish (I. furcatus) ♂ hybrid accounts for >50% of United States catfish production. Blue catfish sperm cannot be collected using non-lethal methods, and thus, males must be sacrificed to determine reproductive quality. To establish gene expression biomarkers of sperm quality, we characterized important sperm traits, ranked blue catfish males based on the curvilinear velocity of their sperm, and sequenced testicular tissue for mRNAs and sRNAs. Of the 43 males characterized, testicular tissue from 4 individuals with low-velocity (155.70 mm/s ± 1.49 SD) and 4 with high-velocity (205.01 mm/s ± 4.63 SD) were chosen for sequencing. No differentially expressed sRNAs were detected between the two sperm performance groups. However, we identified two differentially expressed mRNA transcripts between the low-velocity and high-velocity groups, aqp3a and ly97.3 , both upregulated in the high-velocity group compared to the low-velocity group. These molecular biomarkers of sperm quality in testicular tissue are linked to gamete quality and may be applied for more efficient catfish aquaculture. • Aimed to establish gene expression biomarkers of sperm quality in blue catfish. • Ranked males based on sperm velocity & sequenced testes tissue for mRNAs & sRNAs. • No differentially expressed sRNAs between low & high-velocity sperm. • aqp3a and ly97.3 upregulated in high-velocity sperm compared to low-velocity sperm. [ABSTRACT FROM AUTHOR]

Edwardsiella piscicida has emerged as an important pathogen of channel × blue catfish hybrids cultured in the southeastern United States. With increasing popularity of hybrid catfish and growing concern over E. piscicida, the crossprotective potential of a live‐attenuated E.ictaluri vaccine was evaluated. An immunization bath of E. piscicida (3 × 107 CFU/ml) protected channel catfish against immersion challenge of wild‐type E. ictaluri (1 × 107 CFU/ml) across multiple temperatures and feeding regimens (relative percent survival [RPS]: 89–100%). Channel catfish immunized orally with a live‐attenuated E. ictaluri vaccine/feed admix (3 × 107 CFU/g of feed) were protected against intracoelomic injections of both high (HD) (7.4x105 CFU/fish; RPS = 85%) and low doses (LD) (1.5 × 105 CFU/fish; RPS = 88%) of E. piscicida. Because of limited feed consumption during vaccination, oral immunization of hybrids was followed by a 30‐min immersion bath with cultured vaccine (5 × 106 CFU/ml). Combinatory oral/bath vaccination was ineffective against HD E. piscicida but was protective against LD E. piscicida (48% RPS) and E. ictaluri (96% RPS). Finally, naïve catfish that survived LD E. piscicida injections were protected against E. ictaluri immersion challenge (2 × 107 CFU/ml; RPS: Hybrids 55%; Channels 75%). Results suggest a live‐attenuated E. ictaluri vaccine can also protect channel and hybrid catfish against E. piscicida. [ABSTRACT FROM AUTHOR]

Although a concerted effort in catfish nutrition research in the United States did not begin until the late 1950s/early 1960s, the genesis of both the catfish industry and catfish nutrition research is rooted in studies conducted early in the 20th century. Thus, a historical view delineating the progression of channel catfish, Ictalurus punctatus, nutrition from 1900 to the present is given. Notable nutrition research programs, as well as significant events and accomplishments, will be examined. [ABSTRACT FROM AUTHOR]

Research has demonstrated that by maintaining the minimum dissolved oxygen (DO) concentration in earthen ponds at or above 3.0 ppm, feed intake and growth of Channel Catfish Ictalurus punctatus, Blue Catfish I. furcatus, and hybrid catfish (female Channel Catfish × male Blue Catfish) may be doubled relative to those achieved with the oxygen management regimes typically used on commercial catfish farms. In earlier studies using only emergency aeration or low levels of fixed aeration, the direct effect of stocking rate has been confounded by lower morning DO concentrations in ponds stocked at higher densities due to higher feed input and fish biomass. Although higher stocking rates in those studies did produce greater yields, individual fish growth and feed intake may have been impacted by lower DO levels while appearing to be a direct density effect. In this study, production of hybrid catfish, which were fed daily to satiation in earthen ponds with no water exchange, was compared at low (5,000 fish/acre) and high (20,000 fish/acre) stocking rates while using controlled intensive aeration to maintain a minimum DO over 3.0 ppm in all ponds through the study. We achieved an average net production of 27,704 lb/acre at the higher stocking rate compared to 10,176 lb/acre at the lower stocking rate. Although this is the highest yield reported thus far in traditional static‐water earthen ponds in the southern USA, it may not be the maximum production possible. The average weight of harvested fish was higher at the lower density (2.2 lb versus 1.6 lb), but the feed conversion ratio was identical (1.8) at the two densities. Our data indicate that when morning DO is maintained above limiting concentrations, other factors such as direct density interactions (aggression and/or inhibitory pheromonal feedback) and/or water quality variables unrelated to morning DO—specifically un‐ionized ammonia—may play a role in catfish feed intake and growth but not food conversion. [ABSTRACT FROM AUTHOR]

Channel catfish farming dominates the aquaculture industry in the United States. However, epidemic outbreaks of motile Aeromonas septicemia (MAS), caused by virulent Aeromonas hydrophila (vAh), have become a prominent problem in the catfish industry. Although vaccination is an effective preventive method, there is no vaccine available against MAS. Recombinant proteins could induce protective immunity. Thus, in this work, vAh ATPase protein was expressed, and its protective capability was evaluated in catfish. The purified recombinant ATPase protein was injected into catfish, followed by experimental infection with A. hydrophila strain ML09-119 after 21 days. Results showed catfish immunized with ATPase exhibited 89.16% relative percent survival after challenge with A. hydrophila strain ML09-119. Bacterial concentrations in liver, spleen, and anterior kidney were significantly lower in vaccinated fish compared with the non-vaccinated sham group at 48 h post-infection (p < 0.05). Catfish immunized with ATPase showed a significant (p < 0.05) higher antibody response compared to the non-vaccinated groups. Overall, ATPase recombinant protein has demonstrated potential to stimulate protective immunity in catfish against virulent A. hydrophila infection. [ABSTRACT FROM AUTHOR]

In 2003, the United States adopted anti-dumping tariffs for Vietnamese catfish products entering the country. This study examines how these tariffs have impacted the price relationship between domestically produced and imported catfish products. Cointegration tests confirm a long-run price relationship between domestic and imported catfish, which has persisted despite the anti-dumping tariffs. However, imports are composed of catfish from Vietnam and other countries, with only the former subjected to tariffs. Results from vector error correction models suggest that Vietnamese catfish prices do not significantly influence domestic prices. Conversely, the price of catfish from countries other than Vietnam continues to impact prices received by domestic catfish farmers and processors. The domestic catfish industry is still affected by lower-priced imports from countries other than Vietnam, although some of these may be transshipments that truly originate in Vietnam. This research methodology could be adapted to investigate trade and price interactions among other aquacultured species, which will become increasingly important as global aquaculture expands. [ABSTRACT FROM AUTHOR]

Over the last 20 years, steadily increasing imports into the United States of Vietnamese fish similar to domestically raised catfish have put tremendous strain on an American industry already struggling from natural disasters and rising food and fuel costs.1 American catfish producers have fought declining market share through trade remedies and intensive lobbying efforts that resulted in federal laws to prohibit Vietnamese fish from being marketed as catfish, an effort bitterly opposed by free trade advocates and which has done little to stem the declining sales of domestic catfish.2 The small yet regionally important industry has managed outsized legislative victories thanks to a few well-placed allies in Congress.3 On September 1, 2017, responsibility for the inspection of catfish shifted completely from the Food and Drug Administration, which has jurisdiction over most food and all other seafood, to the Food Safety and Inspection Service of the United States Department of Agriculture, marking the end of an 18-month transitional period.4 Because it is generally more difficult legislatively to eliminate existing programs than it is to establish new ones, this shift should insulate domestic catfish producers from further legislative changes, though it remains to be seen whether the new inspection regime is sufficient to save the American catfish industry. [ABSTRACT FROM AUTHOR]

Aim/purpose - To develop a conceptual model for analyzing the impact of output price risk and material input price risk on price margins. Design/methodology/approach - To analyze the combined effect of output price risk and material input risk on price margins, we use a series of comparative static analyses, GARCH models, and data ranging from 1990/01 to 2012/12. Findings - The theoretical results indicate that the impact of output price risk and the impact of material input price risk on price margins are ambiguous and, to a great extent, hinge on the correlation between output price and material input price. The empirical results show that whole frozen catfish price risk and live catfish price risk negatively affect the price margin for frozen catfish. The empirical results, however, indicate that the risk of the price of live catfish affects markedly the price margin for frozen whole catfish in contrast to the impact of the risk of the price of frozen whole catfish. Research implications/limitations - The empirical results have significant implications for managerial decision-making especially when crafting strategies for improving price margins. Accordingly, in order to beef up the price margin for frozen whole catfish, catfish processors may consider engaging in vertical integration. This paper has some limitations: first, it assumes that firms operate in competitive markets; second, it assumes that firms produce and sell a single product. Originality/value/contribution - Unlike earlier studies that focused solely on the effect of output price risk on price margins, this paper analyzes theoretically and empirically the impact of output price risk and material input price risk on price margins. [ABSTRACT FROM AUTHOR]

Channel catfish, Ictalurus punctatus, remains the USA's largest aquaculture industry. However, in recent years, high feed prices have negatively impacted profitability. Production of ethanol as a biofuel has increased dramatically. Companies have modified their processes to enhance ethanol yield and these modified processes also increase the crude protein content of the byproduct. The object of this study was to evaluate this high-protein dried distiller's grains ( HP-DDG) for its suitability in catfish diets. A total of 25 full-sibling channel catfish (7.1 ± 2.3 g) were randomly stocked into each of twelve 260-L polyethylene tanks to achieve 25 fish per tank. The control diet was similar to a commercial formulation. Experimental diets contained 20, 40, or 40% HP-DDG with added lysine (1% of total diet). There were three replicate tanks per diet. Fish were fed to apparent satiation twice daily for 9 wk. Average harvest weights for fish fed the 40% HP-DDG diet without lysine supplementation (57.0 g) were significantly smaller than that for fish fed the control diet (77.7 g). Average harvest weights of fish fed 20% HP-DDG (86.8 g) were significantly greater than that of fish fed either 40% HP-DDG (57.0 g) or 40% HP-DDG + lysine (73.7 g). There were no significant differences in feed conversion ratios or survivals among treatments, which overall averaged 1.1 and 99%, respectively. These data indicate that HP-DDG appears to be a suitable ingredient in channel catfish diets up to at least 20% of the total formulation. Data also indicate that inclusion levels of at least 40% HP-DDG are likely limiting in lysine. [ABSTRACT FROM AUTHOR]

The trematode Bolbophorus damnificus is associated with reduced production in farm-raised catfish in the southeastern United States. Previous research demonstrated that even mild outbreaks, which may go unnoticed by producers, can result in >60% reduction in net return due to decreased feeding and trematode-induced mortality. While infectivity rates in channel (Ictalurus punctatus) and hybrid catfish (I. punctatus x I. furcatus) are similar, hybrid catfish experience lower mortality when exposed to comparable numbers of Bolbophorus cercariae than channel catfish cohorts. This study compared physiological responses in channel (21.4 ± 0.93 g) and hybrid (27.5 ± 2.63 g) catfish fingerlings exposed to 450 cercariae/L. Fish were sampled over the next 49 days for hematocrit, hemoglobin, red blood cell (RBC) concentration, plasma glucose, plasma lactate, and plasma osmolality. Exposed channel and hybrid catfish experienced a dramatic drop in hematocrit, hemoglobin, and RBC concentration during the peak mortality window associated with metacercarial development, but recovered afterwards, suggesting an anemic response to the development of the parasite and subsequent recovery once metacercarial encapsulation is complete (∼15 days post-exposure). There were no differences over time in any of the plasma parameters measured, but there was an overall decreased osmolality in both exposed groups, suggesting a prolonged low-level stress response to infection. There was high mortality in the exposed channel catfish groups from days 9 to 15 post-infection, consistent with previous studies. Comparably, hybrids appeared healthy and active throughout the trial with only negligible mortality. In all trials, infected fish presented clinical signs consistent with B. damnificus infection and all exposed fish had visible metacercariae below the skin. There was a substantial anemic response in both catfish types, suggesting the physiological response to B. damnificus infection may not differ between channel and hybrid catfish and the significant differences in mortality may be attributed to survivor bias, hybrids greater tolerance of the anemic state or other unidentified factors. The biological and economic implications of these findings are unclear, but the behavioral differences observed between the two fish groups in reponse to B. damnificus , coupled with reduced mortality in hybrids, supports previous work indicating hybrids are more tolerant of B. damnificus infection and outbreaks in hybrid catfish may not yield the same deleterious effects as channel catfish. • Channel and hybrid catfish were exposed to B. damnificus to measure physiological reponse to infection. • An anemic response was observed in catfish infected with B. damnificus. • Physiological response to infection suggests a prolonged low-level stress response. • Hybrid catfish experienced lower mortality due to infection than channel catfish. • Hybrid catfish may be more tolerant of B. damnificus infection, possibly resulting in reduced production losses. [ABSTRACT FROM AUTHOR]

Several families of catfish species are extensively aquacultured around the world; however, only those from the family Ictaluridae can be labeled as catfish in the United States. Non-Ictalurid catfish species that are marketed as “catfish” in the USA are considered misbranded. Misbranding in general has led to an increased interest in developing deoxyribonucleic acid (DNA)-based methods such as DNA barcoding, polymerase chain reaction restriction fragment length polymorphism, and DNA microarrays with fluorescence detection for the identification of fish species. In this proof-of-concept study, DNA microarrays coupled with a newly developed mid-infrared imaging detection method were applied to the identification of seven species of catfish for the first time. Species-specific DNA probes targeting three regions per species of the cytochrome c oxidase 1 (barcoding) gene were developed and printed as microarrays on glass slides. Deoxyribonucleic acid targets labeled with biotin were hybridized to their complementary probes using a strategy that allowed the selective formation of a silver layer on hybridized spots needed for detection. Using this three-probe format, the seven species were all identified correctly, even when a limited number of false positive spots were observed. Raman spectroscopy was employed to further characterize the arrays. [ABSTRACT FROM AUTHOR]

Catfish market research is important in terms of the viability and sustainability of the catfish aquaculture industry in the U.S. Analysis of market trends, retail level price and sales volume have particular importance in the context of the industry's efforts to promote and market their products. Using retail level scanner data, this study examined the market trends of different catfish product forms. The study also investigated the factors affecting prices and sales for frozen catfish products. The present study is a pioneer in using market/city level retail scanner data to study marketing behavior of catfish products under different product categories (i.e., breaded, unbreaded and entrees). The results of the study highlight a need for a non-price competition strategy for catfish retail market. This includes several activities that attempt to provide added value or incentives to consumers, wholesalers, retailers, or other organizational customers to stimulate immediate sales. [ABSTRACT FROM AUTHOR]

This investigation uses farm-level data from the U.S. Census of Agriculture to evaluate the economic performance of the aquaculture industry in Hawaii. We first examine the entire aquaculture industry by assessing its profitability, efficiency, and input cost structure over time and across economic farm sizes; we then proceed to analyze the farms at the individual subsector levels of crustacean, Chinese catfish, other foodfish, and ornamental farms. The results reveal a wide variation in performance across farms, even within the same subsectors. In 2007, 57.6% of the aquafarms generated a profit; however 39.4% of the farms were found unable to cover their variable cash expenses. The presence of significant economies of scales were detected in performance with full-time operations being found more profitable and efficient than part-time operations. Finally, Hawaii's labor cost share for aquaculture enterprises is about 3.5 times greater than that found on the continental United States. [ABSTRACT FROM PUBLISHER]

Marketed as the “nugget” in the seafood trade, the belly flap of the catfish (Ictalurus punctatus) is a residual portion with minimal value due to its elevated fat content and unsightly black peritoneal membrane. To ameliorate these shortcomings, a variety of marinated and breaded nugget formulations were developed and screened in the laboratory. Four of these were evaluated further for organoleptic traits using consumer sensory panels. Next, an in-store conjoint survey was conducted in 13 supermarkets in eight cities in the southern United States to elicit consumers' preferences for price ($3.28/kg, $10.12/kg, $16.51/kg), color of breading (light, medium, dark), cooking method (fried, baked), and country of origin (United States, China). Cluster analysis suggested three consumer segments: a price-sensitive segment, a U.S.-origin segment, and a dark-breading segment. Membership in the segments was related to age, ethnicity, and education. Unusually strong preferences for higher prices and country of origin were investigated in detail. [ABSTRACT FROM PUBLISHER]

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The antimicrobial activity of various essential oils and carvacrol was determined on fresh raw catfish fillets against a 4-strain Listeria monocytogenes mixture representing serotypes 1/2b, 3b, 4b, and 4c that were predominantly isolated from catfish processing environments. Thyme oil, oregano oil and carvacrol exhibited concentration and time dependent responses in broth against L. monocytogenes; for example 0.5% concentrations resulted in 4 log CFU/mL reduction within 30 min whereas 0.1% concentrations required more than 24 h for the same level of reduction. Lemon, orange, and tangerine oils, at 0.5% showed listeriostatic effect in which 4 log CFU/mL of the initial L. monocytogenes load was unchanged at 4 °C in 10 d whereas 1% concentrations were listericidal in a time dependent manner. Apart from carvacrol, efficacy of tested essential oils in reducing L. monocytogenes and total microbial load from catfish fillet was very limited. Dipping treatment of catfish fillets in 2% carvacrol solution for 30 min at 4 °C reduced L. monocytogenes to an undetectable level from their initial load of 5 log CFU/g and reduced total microbial load from catfish fillets by approximately 5 log CFU/g. In sensory analysis trained panelist preferred control samples over 2% carvacrol treated samples implying potential limitation in applicability of carvacrol for fillet treatments. [ABSTRACT FROM AUTHOR]

Abstract: In the United States, catfish industry is a mature industry with a long history of success. However, the industry faces numerous challenges while it evolves and adapts to shifting inputs and market demands, such as the dramatic increase in the price of feed ingredients and requests for more consistent fillet color. There is considerable interest in reducing the cost of production diets either by reducing the protein content or by using alternative ingredients such as corn gluten feed. Towards this goal, a pond study was conducted to evaluate the utilization of alternative feed containing 20% corn gluten feed compared to traditional feed without corn gluten feed for the production of channel-blue hybrid catfish. Both alternative and traditional feeds were formulated with two protein contents (28% and 32%). In addition to traditional parameters, the xanthophyll contents on the fish fillets were determined. Upon initiation of the pond trial, 600 hybrid catfish fingerlings were stocked in each of 20 0.04-ha ponds, with a mean weight of 34.5g/fish. Fish were fed four experimental diets once daily to apparent satiation over a summer growing season. No significant differences were found in growth performance and feed utilization among the four treatments, including gross and net yield, total amount of feed fed, estimated feed conversion ratio and survival. No significant differences were found in mean individual fish weight and mean total body length at harvest, relative weight index and dressout (headed and gutted). However, intraperitoneal fat ratio was significantly lower in fish fed the alternative feeds indicating lower energy content of the diet. No significant differences were observed in hematology and immune response indices. Xanthophyll levels in diets and in fillet were linearly related, but without discernible yellow color. These data generally indicate that channel-blue hybrids can efficiently utilize all the four experimental diets with satisfying production result. [Copyright &y& Elsevier]

Most commercial catfish ponds in the United States contain fish of various sizes ranging from 35 g fingerlings to >1.5 kg fish. Catfish farmers, when required by lenders and bankruptcy judges to estimate pond inventories, rely primarily on methods based on daily feeding response of catfish. These methods have not been evaluated systematically. Daily feed data from experimental (0.1-ha and 1.6-ha) and commercial (4-ha) ponds were used to characterize feed response of catfish and to compare the accuracy and precision of feeding response methods used to estimate fish inventories. Daily feed consumption of catfish was highly variable. Inventories estimated with feed response methods had errors of 16% to 37% in single-batch production and 28% to 49% in multiple-batch production. Inventories estimated with feed response methods were too inaccurate and variable for reliable use in management by lenders or the courts. [ABSTRACT FROM PUBLISHER]

Catfish farmers in the United States (U.S.) are facing reduced market share, falling prices and reduced profitability for their farm-raised catfish, and these problems have been compounded by dramatic increases in global supply of catfish, basa and tra. The objective of this article is to study the growth and determinants of catfish, basa and tra imports to the United States from Vietnam, China and Thailand. The study has applied an augmented gravity model of international trade for this purpose. The results reveal that U.S. imports from Vietnam are significantly affected by variables like: price of the U.S. farm-raised catfish, population of Vietnam, population of the U.S., per-capita gross domestic product (GDP) of Vietnam, freight index, tariff, generic advertisement expenditure of the Catfish Institute (TCI), and country of origin and catfish labeling. Catfish, basa and tra imports from China are affected by population of the United States, per-capita GDP of China, and country of origin and catfish labeling. Finally, U.S. basa and tra imports from Thailand are affected by: price of imported catfish, basa and tra from other countries, population of Thailand, per-capita GDP of Thailand, per-capita GDP of the United States, and country of origin and catfish labeling. Findings of this study have policy implications to revive the U.S. catfish industry. [ABSTRACT FROM AUTHOR]

Using ‘Constant Market Share’ analysis, we have decomposed the growth of catfish exports of major catfish exporting countries to the United States (U.S.) into structural, competitive and second-order effects and their sub-components. We have also studied competitiveness of the U.S. farm-raised catfish in the domestic market. The U.S. farm-raised catfish industry could not harvest the benefits of the supply-demand gap created in the U.S. due the shift of Vietnam's catfish exports away from the U.S. after 2003; however, China and Thailand and also some other catfish exporting countries derived the greatest extent of the benefits. Decline in the competitiveness of Vietnam's catfish exports to the United States has made China and Thailand catfish more competitive in the U.S. market. The benefits of increased demand for total fisheries products at the world level to the U.S. catfish industry have been marginalized by decline in competitiveness of the U.S. farm-raised catfish in domestic market. [ABSTRACT FROM AUTHOR]

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

Noturus munitus (Frecklebelly Madtom) is a diminutive catfish with a disjunct distribution across the southeastern United States in large rivers and tributaries of the Mobile Basin and Pearl River drainage. Its distribution has contracted since extensive river modification began throughout its range in the 1960s, and it is likely extirpated from the Alabama River. We collected 242 specimens of N. munitus from a gravel island in the Cahaba River on the Coastal Plain in Alabama from May 2005 to March 2007 to examine life-history characteristics. Adults were associated with fast flow over large gravel at depths of 0.5-1.0 m. Young (<23 mm) were found at water depths of 0.4-0.5 m. Gonad development indicated a reproductive season from May to August, with collection of young-of-the-year in June and July supporting a mid- to late-summer spawn. Stomach content analysis revealed a diet similar to other Noturus species and dominated in volume by Baetidae nymphs (31.2%), Hydropsychidae larvae (20.3%), and Simuliidae larvae (19.7%). Some seasonal and sex differences in diet were apparent. Relative fecundity data indicate that N. munitus is one of the most fecund madtoms of the subgenus Rabida (mean of 30.6 mature oocytes) studied thus far. Few males were found in riffles during summer, and no young were found in riffles outside summer, indicating potential sex and size differences in seasonal habitat use. This knowledge is important for conservation of the species. [ABSTRACT FROM AUTHOR]

The article discusses the farm-raised catfish in the U.S. which provide one of the most affordable and environmentally sustainable sources of safe, tasty, high-quality animal protein available to American consumers. It notes that cultivated catfish of various species surpass all aquacultured finfish except carp and salmon on its sales which is measured by numbers of fish, tonnage, or dollar value. It also notes that in the U.S., catfish is the most widely produced freshwater fish. It also notes that 728 million catfish weighing 28 million pounds were sold for 373 million dollars in 2009.

Estimating an age-length relationship is a routine aspect of many fisheries studies and is simplified by the use of commercially available computer programs. These computer programs may be misleading since a result can be produced irrespective of the quality or the extent of the data, and there is some concern that back-calculated age-length relationships are sensitive to the sample size and composition. We investigated this issue by comparing estimates of mean back-calculated lengths at age and growth rates derived from subsets of a large sample of wild channel catfish Ictalurus punctatus (N=788) collected in 2001 and 2002 from 9 rivers in Mississippi, United States. Estimates of growth rate varied among subsets consisting of individual year class (2-6) of channel catfish separated from the overall sample. For nine subsets, comprising randomly-selected and increasing proportions of the overall sample (20%-100% at 10% increments of the overall sample), growth was similar. However, growth differed for a subset representing a random 10% of the overall sample. Lengths at age and growth rates derived from each of the 2001 and 2002 components of the sample both differed. All results were significant at P < 0.05. [ABSTRACT FROM AUTHOR]

Pangasius catfish, primarily tra (Pangasius hypophthalmus) and basa ( Pangasius bocourti), are farm-raised catfish imported from Asia and have become a common substitute for domestic catfish, grouper, and other high-valued fish in restaurant-served dishes in the United States. This article reports on the development of a monoclonal antibody-based sandwich enzyme-linked immunosorbent assay (ELISA) for the identification of cooked Pangasius fish, basa, and tra. The assay uses a pair of monoclonal antibodies (MAbs F7B8 and T7E10) specific to a heat-stable 36-kDa protein present in a saline extraction of the fish muscle; MAb F7B8, which cross-reacts to all fish species, is the capture antibody and the biotin-conjugated MAb T7E10, which is specific to Pangasius fish, is the detection antibody. This sandwich ELISA reliably identified fully cooked basa and tra from more than 70 common finfish, shellfish, land animal species, and other protein materials tested. It can also sensitively detect 0.5% of adulterated basa or 0.1% tra in a mixed crabmeat products with low intra-assay (%CV: 2.59 to 4.14) and inter-assay (%CV: 3.36 to 3.71) variabilities. The new assay provides a rapid and reliable means of distinguishing fish in the Pangasiidae family from other common food fish and nonfish species and will greatly assist efforts to discourage the illegal practice of substituting high-value popular fish species by the cheaper farm-raised imported Pangasius fish at the retail and restaurant levels. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of various agglomerated phosphate blends on the quality of vacuum-tumbled catfish fillets. Catfish fillets were tumbled with a brine solution at 15% over initial, raw weight prior to tray-packing and storage at 4°C for 10 days. Fillets were evaluated for protein exudate, tumbling yield, color, pH, cooking loss, tenderness, purge loss, and shelf life. A specific blend of agglomerated sodium phosphates (AGSP) that contains mono-, tri-, and polyphosphates had significantly less protein (p < 0.05) exudate and significantly higher pH (p < 0.05) than other treatments. All phosphate treatments significantly increased (p < 0.05) tenderness and significantly decreased (p < 0.05) purge loss, but agglomerated phosphate blends significantly decreased (p < 0.05) cooking loss and yellowness. Psychrotrophic plate counts for all phosphate treatments were similar to the control at each storage time. All phosphate treatments improved the yield and quality of catfish fillets, but the use of AGSP may optimize quality attributes. [ABSTRACT FROM AUTHOR]

The original description of Henneguya adiposa, a myxozoan parasitizing channel catfish Ictalurus punctatus, is supplemented with new data on spore morphology, including photomicrographs and line drawings, as well as 18S small-subunit (SSU) ribosomal DNA (rDNA) sequence. Elongate, translucent, linear plasmodia were situated between the connective tissue bands of the adipose fin. The myxospore possessed an elongate, lanceolate spore body, flattened parallel to the suture line: 17.1 ± 1.6 μm (range 14.7-20.5) in length, 4.1 ± 0.3 μm (range 3.4-4.6) wide in valvular view, and 3.7 ± 0.3 μm (range 3.2-4.0) thick in sutural view. Polar capsules were pyriform and unequal in length, measuring 7.2 ± 0.6 μm (range 5.8-8.3) long and 1.3 ± 0.2 μm (range 0.9-1.9) wide, with at least 8 turns in the polar filament coil. The caudal appendages were 38.0 ± 6.2 μm (range 23.2-48.8) and split posteriorly. The total length of the spore was 55.6 ± 6.5 mm (range 40.7-65.8). Phylogenetic analysis of 18S SSU rDNA sequence data placed this isolate within the Myxobolidae, indicating a close relationship to a group of Henneguya species parasitizing channel catfish in the southeast United States. [ABSTRACT FROM AUTHOR]

The absolute price version of the Rotterdam model was used in the estimation of U.S. catfish demand where catfish was differentiated by product cut (whole, fillet, and other) and product form (fresh and frozen). Likelihood ratio tests were used to determine the importance of product form in demand (product form aggregation). Likelihood ratio tests were also used to determine if fresh products were separable from frozen products (product form separability). Product form aggregation was rejected at a probability of 0.999, suggesting that fresh and frozen catfish products are not homogenous. The hypothesis, no product form separability, failed to be rejected at the 0.05 significance level, but was rejected at the 0.01 significance level. Test results suggest that it is more acceptable to focus on a single product group (e.g., frozen products) than to assume that catfish products are perfectly aggregatable across product forms. [JEL classifications: Q11, Q13, Q22]. © 2009 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Four different catfish oil extraction processes were used to extract oil from catfish viscera: process CF1 involved a mixture of ground catfish viscera and water, no heat treatment, and centrifugation; process CF2 involved ground catfish viscera (no added water), heat treatment, and centrifugation; process CF3 involved a mixture of ground catfish viscera and water, heat treatment, and centrifugation; process CF4 involved ground catfish viscera, enzymatic hydrolysis, and centrifugation. Chemical and physical properties of the resulting of catfish oils were evaluated. The CF4 process recovered significantly higher amounts of crude oil from catfish viscera than the other 3 extraction methods. The CF4 oil contained a higher percent of free fatty acid and peroxide values than CF1, CF2, and CF3 oils. Oleic acid in catfish oil was the predominant fatty acid accounting for about 50% of total fatty acids. Weight loss of oils increased with increasing temperatures between 250 and 500 °C. All the catfish oil samples melted around −32 °C regardless of the extraction methods. The flow behavior index of all the oil samples was less than 1, which indicated that the catfish oils exhibited non-Newtonian fluid behavior. The apparent viscosity at −5 and 0 °C was significantly higher ( P < 0.05) than those at 5, 10, 15, 20, 25, and 30 °C. The average magnitude of activation energy for apparent viscosity of the oil was higher for CF2 than CF1, CF3, and CF4. [ABSTRACT FROM AUTHOR]

Simple Summary: Catfish aquaculture is a prominent agricultural sector for foodfish production in the Southern United States. Catfish producers often experience high-level mortality events due to bacterial pathogens. In many instances, co-infections caused by multiple bacterial fish pathogens are isolated during diagnostic cases. These bacterial–bacterial interactions may alter the infection dynamics, and many of these mechanisms and interactions remain unclear. Furthermore, these co-infections may complicate disease management plans and treatment strategies. The current review provides an overview of the prevalent bacterial pathogens in catfish culture and previously reported instances of co-infections in catfish and other production fish species. Catfish production is a major aquaculture industry in the United States and is the largest sector of food fish production. As producers aim to optimize production yields, diseases caused by bacterial pathogens are responsible for high pond mortality rates and economic losses. The major bacterial pathogens responsible are Edwardsiella ictaluri, Aeromonas spp., and Flavobacterium columnare. Given the outdoor pond culture environments and ubiquitous nature of these aquatic pathogens, there have been many reports of co-infective bacterial infections within this aquaculture sector. Co-infections may be responsible for altering disease infection mechanics, increasing mortality rates, and creating difficulties for disease management plans. Furthermore, proper diagnoses of primary and secondary pathogens are essential in ensuring the correct treatment approaches for antimicrobials and chemical applications. A thorough understanding of the interactions and infectivity dynamics for these warm water bacterial pathogens will allow for the adoption of new prevention and control methods, particularly in vaccine development. This review aims to provide an overview of co-infective pathogens in catfish culture and present diagnostic case data from Mississippi and Alabama to define prevalence for these multiple-species infections better. [ABSTRACT FROM AUTHOR]

With the popularity of catfish and tilapia in the healthy diet, the consumption and harvesting of farm-raised finfish have increased. Since 1987 the pathogenic bacterium Listeria monocytogenes has been isolated from seafood, particularly farmraised catfish in the United States. Seafood isolates of L. monocytogenes are now available. In order to maintain the raw finfish product, nonthermal interventions to remove bacterial pathogens need to be evaluated using these isolates. A nonthermal intervention process, irradiation, was used to determine the destruct values of the L. monocytogenes seafood isolates along with a nonpathogenic Listeria strain and an L. monocytogenes strain previously studied. The irradiation destruct values were obtained for each individual isolate inoculated on raw and frozen catfish or tilapia irradiated at 4 or -10°C. The Dradiation-values obtained for L. monocytogenes inoculated on raw or frozen catfish did not differ (P > 0.05) from the values obtained for strains inoculated on the raw or frozen tilapia. The Dradiation-Values ranged from 0.48 to 0.85 kGy, with an average of 0.62 ± 0.09 kGy, which is typical for Listeria. The data obtained have identified a multi-isolate cocktail that can be used for future radiation inactivation studies for L. monocytogenes inoculated on finfish. [ABSTRACT FROM AUTHOR]

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 black madtom (Noturus funebris) is a diminutive catfish (maximum standard length 124 mm) found throughout the southeastern United States. Life history aspects of N. funebris were examined using 298 specimens from Blue Girth Creek, a sand-bottomed second-order tributary to the Cahaba River in Bibb County, Alabama, collected in 1987-1988. Noturus jimebris was associated with undercut banks, root masses, and woody debris. The youngest reproductive female was 3 years old. Noturus funebris produces many eggs (mean = 109 ova per female) compared to other species within the subgenus Schilbeodes; however, relative fecundity (oocytes per g body weight) indicated a lower relative position in the subgenus. Analysis of gonads and presence of young-of-the-year indicated a spawning season from late June to August. One nest of N. funebris was collected in July 1988 in a glass bottle with 70 eggs. Sex ratio was nearly 1:1. in summer 2005, placement of 30 clay flowerpots as in-stream artificial nesting cavities yielded no additional nests, which suggested a preference for smaller, closed cavities. Analysis of stomach contents indicated a similar diet to other Noturus species, which consisted mainly of decapods and larvae of dipterans, mayflies, and caddisilies. Odonates made up the higher percent of diet volume in winter, crayfish in the spring, and plant material in the summer. Length-frequency data indicated four size (age) classes. with most individuals in the age 0+ and other classes containing similar proportions of individuals. A potential age-4 class consisted of three individuals greater than 108 mm SL. [ABSTRACT FROM AUTHOR]

During the examination of Lake Tanganylkan fishes held at the American Museum of Natural History, several specimens of the genus Chrysichthys could not be Identified to any of the known species from the lake or elsewhere. This material is believed to represent a new species, distinguished from other species of Chrysichthys on the basis of a weakly expressed or absent postcleithral process, 14-16 rakers on the first gill arch, toothplates of the premaxillae and palate bearing small and tightly packed teeth, vomerine toothplates widely separated and narrower than those on the pterygoids, supraoccipital broad and contacting the predorsal plate, body width at pectoral-fin insertions 4.9-5.3 (5.1 ± 0.1) times in SL, interorbital width contained 3.0-4.1 (3.4 ± 0.4) times in HL, distance between posterior nares contained 4.0-4.8 (4.3 ± 0.3) times in HL, maxillary barbels contained 4.1-5.5 (4.7 ± 0.8) times in SL, and the distance between posterior margins of adipose fin and hypural plate contained 5.1-6.0 (5.5 ± 0.3) times in SL. [ABSTRACT FROM AUTHOR]

I present a method and examples of a piecewise function in nonlinear regression to estimate size-related differential mortality using age- and length-based models for data collected from a Tennessee River (Alabama) population of blue catfish Ictalurus furcatus. The model is similar to. catch curve regression but computes two slope coefficients that can be used to estimate mortality; these slopes meet at a joint (or knot) that estimates the age or length at which differences in mortality occur. The model is described as loge(Ni) = b0 - (b1 + b2)ti, where Ni is the number of fish collected for the ith age or length interval; ti is the age or relative age of the ith age or length interval; b0 is the intercept coefficient; b1 is the slope coefficient and is equal to b*2 when ti is less than or equal to the knot and 0 otherwise; b2 is a second slope coefficient and is equal to b*1 - b*2 when ti is greater than the knot and 0 otherwise; and b*1 and b*2 are estimated by the model. For these data, fish ranged in age from 3 to 25 years and ranged in total length (TL) from 301 to 1,291 mm. With this piecewise nonlinear approach, the fit between age or length and loge (Ni) improved over that determined with linear catch curves. For both age- and lengthbased structure data, annual mortality for small blue catfish ranged from 0.41 to 0.49 for younger and smaller fish (age ≤ 10 years; TL ≤ 684 mm). For larger, older fish (age = 11-25 years; TL > 685 mm), annual mortality estimates ranged from 0.08 to 0.16. Observations of the fishery indicated that anglers harvested smaller blue catfish (<562 mm TL); harvest of larger fish was nil, which probably accounted for the size-related differences in mortality. I provide a computer program to derive estimates of size-related mortality using piecewise nonlinear regression. [ABSTRACT FROM AUTHOR]

Although there are differences in performance between genetic groups of channel catfish, identification and management of these groups is difficult because catfish strains look alike and individuals cannot be tagged efficiently. Thus, US catfish producers have not been able to objectively identify fish from different strains or populations, and it has been difficult for them to maintain the genetic purity of populations on the farm. We have developed a multiplexed microsatellite genotyping system to define catfish populations based on allelic frequency and exclusion. A commercial catfish genotype database was developed using catfish samples collected from 24 processing plants in the four main US catfish-producing states. The utility of the system was tested by the molecular characterization of the USDA103 research strain. Using eight microsatellite loci, the probability of falsely classifying an individual non-USDA103 catfish as a USDA103 was 0.0065. From a sample of 50 fish from a putative USDA103 pond, the probability of falsely including two non-USDA103 fish was 1 × 10−105, and the conservative probability of falsely excluding two USDA103 fish was 1 × 10−6. This genotyping system provides channel catfish producers with an objective mechanism for identification and management of genetically selected fish. [ABSTRACT FROM AUTHOR]

Productivity growth of the catfish-processing sector in the United States was measured over the time period of 1986 through 2005. The analysis evaluated the efficiency with which products are produced by catfish processing plants. The Malmquist index is employed to decompose the total factor productivity into growth associated with technical efficiency change and technological progress. The relationship between Farrell's measure of technical efficiency and the Shepard's distance function provides the theoretical foundation for estimating the Malmquist production index using data envelopment analysis. The results indicate that, between 1986 and 2005, there was no technical progress or adoption of new techniques with significant impact on catfish processing. Technical efficiency change, which is associated with input use efficiency, varied with type of fish size processed. It decreased from 1985 to 1995 as the industry struggled to establish the most efficient fish size to process. Between 1995 and 2005 the fluctuation continued but at a higher mean. Productivity growth and long-term competitiveness are likely to result from adoption of new processing innovations by the catfish-processing sector. [ABSTRACT FROM AUTHOR]

Hoplosteernum littorale is a South American catfish (Family Callichthyidae) first discovered in the United States in 1995 in Florida. The presence of H. littorale was documented from early 2002 to late 2003 in Lake Tohopekaliga (Kissimmee River Basin) in central Florida. In this paper, 22 H. littorale nests and nest sites are described. The characteristic bubble nests were present from late May to early September, with number of nests peaking in August when water stage and temperature were both high. Nest habitats (shallow, open marshes) and timing of nest construction (rainy season) were similar to what has been reported for H. littorale in its native range. Most nests (n = 14) were in areas dominated by Hydrilla verticillata and constructed largely from parts of this Asian aquatic plant, representing a unique association between two non-native species. Nevertheless, during August, as water levels increased, nesting shifted from H. verticillata-dominated communities to use of inshore grass zones dominated by Luziola fluitans. Knowledge of H. littorale nesting seasonality and habitat preferences may be useful for any efforts to control or manage this invasive fish. [ABSTRACT FROM AUTHOR]