Edam and Cheddar whey were thermized (T) for different time periods (5–30 min) at 70 degrees Celsius, vacuum evaporated, and spray dried to obtain whey powders (WP). Native and thermized WP were evaluated for antioxidative properties. Edam and Cheddar WP significantly reduced thiobarbituric acid-reactive substances (TBARS) and peroxide value (PV) in ferric-catalyzed soybean oil emulsions. Thermization significantly improved antioxidative properties of WP with 5T, 10T, and 15T treatments showing better protective effects compared to 20T and 30T treatments. Based on these results, native (0T) and thermized (5T, 10T, and 15T) Edam and Cheddar WP coatings, with and without enzymatically hydrolyzed casein (CH), were used to reduce oxidative degradation and moisture loss of cubed beef steak and pork loin. Thermized treatments significantly reduced TBARS and PV in both types of meat, with CH containing treatments showing enhanced antioxidative properties. Protein oxidation as reflected by carbonyl formation and a decrease in sulfhydryls was also reduced by thermization. Treated and native WP coatings significantly reduced moisture loss of meat samples. Cubed beef steak treated with Cheddar WP coatings were evaluated for microbiological quality and basic sensory attributes. Although not statistically significant, 5T, 10T, and 10TCH treatments numerically showed potential for microbial reduction up to 4 days of storage. Sensory evaluation showed significant protection of key sensory attributes by treatments throughout the storage period when compared to controls with the 5 min thermization showing the best effect on lowering offlavor development based on sensory scores. The effect of pH and glucomannan (GM) on antioxidative properties of thermized (5T) Cheddar WP coatings applied to catfish fillets was also investigated. Coatings at pH 7.0, 7.5, and 8.0 (with GM) showed markedly greater protection against oxidative degradation compared to coatings without GM, as reflected by TBARS values and PV after 7 days of storage. Carbonyl formation and oxidation of sulfhydryl groups were also significantly reduced by coatings containing GM. Cheddar WP-based edible coatings (pH 7.0–8.0) with GM markedly reduced lipid oxidation and protein oxidation of fresh catfish fillets.

The gram-negative bacteria Edwardsiella ictaluri causes significant economic losses in aquacultured fish. Generally considered host-specific to catfish, there are reports of E. ictaluri outbreaks from other aquacultured species, including ornamental fish raised in the southeastern U.S. Thus, a comprehensive phenotypic and genotypic characterization of E. ictaluri isolates from catfish and ornamental aquaculture was warranted. Morphological, biochemical, and protein profiles of catfish and ornamental derived isolates were mostly similar. Plasmid profiles of wild-type isolates were consistent within groups. Analysis of putative anti-microbial resistant isolates from catfish revealed the presence of multi-drug resistant plasmids. Genomic comparisons indicated marked differences among host groups, including unique T4SSs and phage elements among ornamental fish-derived E. ictaluri isolates. An optimal MLSA scheme consisting of eight reference genes was defined, revealing isolates from catfish and ornamental aquaculture form two discrete phyletic lineages. This study advances our understanding of E. ictaluri affecting two important agricultural commodities in the U.S.

This research provides a comprehensive picture of the economic status of the U.S. catfish industry through investigating several critical economic aspects such as technological progress, functional production relationships in intensive systems, regulatory costs, and economic contribution of the industry. The use of primary data is a unique aspect of this work reflecting the economic realities of catfish farms. Primary data collected through extensive in-person farm surveys covered over two-thirds of the catfish production areas in the U.S. The results of the study provided evidence of intensification in the U.S. catfish industry through increased adoption of two relatively new alternative production systems viz; intensively aerated ponds (6,315 ha) and split ponds (1,176 ha). The use of complementary technologies such as hybrid catfish on 53% of the catfish producing area and increased fixed-paddlewheel aeration rate of over 7.8 kW/ha also provided proof of technological progress on U.S. catfish farms. This study also identified critical factors contributing to productivity in increasingly adopted alternative production systems through two distinct production function models. Feed fed, as well as stocking biomass were found to be significant variables in both production functions. Results indicated further room for improvement in the use of inputs to increase production, especially in feed management. Along with identifying the nuances in the catfish industry, the study quantified regulatory costs on U.S. catfish farms at $45 million. Although faced with several hardships on the production front, the U.S. catfish industry contributes over $1.9 billion to the regional economy, supports more than 9,100 jobs, and generates over $78 million in tax revenues. The findings of the study serve a multitude of stakeholders including aquaculture farmers, researchers, Extension specialists, and policymakers who work towards improving the economic sustainability of the catfish industry as well as the U.S. aquaculture industry.

Although U.S. commercial catfish aquaculture ponds are in temperate regions and experience cool to cold temperatures during the winter, few studies have investigated the effects of low temperatures on catfish physiological processes. Therefore, growth, metabolism, swimming performance, and blood variables were compared between channel (Ictalurus punctatus), blue (I. furcatus), and hybrid (I. furcatus x I. punctatus) catfish at 10 and 20°C. Accelerometers were also used to evaluate relationships among acceleration, metabolism, and tail beat frequency (TBF) during swimming performance tests. Channel catfish experienced the greatest growth, yet growth was diminished across all fish types at 10°C. Metabolic processes, swimming performance, and related blood variables were also diminished at 10°C. Relationships among acceleration, metabolism, and TBF were found indicating cold temperatures inhibit maximum production in catfish and provide initial steps for creating holistic bioenergetic models for further application.

Channel catfish farming is the largest aquaculture industry in the U.S., and virulent Aeromonas hydrophila is an important re-emerging bacterial pathogen of farmed catfish. A. hydrophila is ubiquitous in the aquatic environment and causes motile Aeromonas septicemia (MAS) in farmed catfish. A. hydrophila infection is challenging to treat due to rapidly progressive mass mortalities. Although florfenicol has been used in managing outbreaks, acute onset of anorexia, drug cost, and emergence of antimicrobial-resistant strains are significant concerns. Prevention of MAS by vaccination could be a promising approach, but a commercial vaccine is not available. Thus, it is critical to develop effective vaccines against A. hydrophila to prevent losses in the catfish industry. The overall objective of this study is to develop effective live attenuated A. hydrophila vaccines and understand macrophage-A. hydrophila interactions. To achieve this, potential virulence-related genes from T6SS, secretion pathway, tat pathway, and flagellar system were deleted by in-frame, and mutants’ virulence and protection were evaluated in channel catfish. Also, macrophage-A. hydrophila interactions were explored by studying global gene expression to understand macrophage responses to A. hydrophila and A. hydrophila virulence mechanisms

From June to November 1967, a study on channel catfish, lctalurus punctatus (Rafinesque), in Mud Lake, Utah Co., Utah was undertaken. The objectives were (I) to estimate if channel catfish are increasing or decreasing in Mud Lake, (2) to estimate the mean size of adult channel catfish in Mud lake, (3) to determine which environmental factors effect the catch of channel catfish, and (4) to determine if the channel catfish in Mud lake are residents year round. A total of 310 mature channel catfish and 920 carp were collected with four hoop nets. Two fingerling were captured by seining. Ratios between carp and channel catfish over a 17 year period had been established which indicated a possible increase in the channel catfish population. With the exception of the fingerIings all channel catfish captured were at least 36.8 cm long with an average of 50.2 cm. A comparison between environmental factors (water temperture, turbidity, water level, and barometric pressure) and the catch showed that only water temperature changes had a statistically significant influence. Large catches during June, July, August, and September were recorded. In later months the numbers of fish captured decreased and no channel catfish could be seen when tho water cleared. It appears that channel catfish utiIize Mud Lake only during the summer.

Swedish populations of Wels catfish (Silurus glanis) experienced severe declines during the 19th and 20th centuries. The main causes for the decline were loss of suitable spawning habitat and fragmentation of populations. Currently, three native and two reintroduced populations remain in Sweden. Thanks to national protection and progress in restoring habitats, population sizes have increased over the past three decades. Previous studies that used microsatellite loci have found that genetic diversity and effective population sizes in Sweden are low, while population differentiation is high. A study that used whole genome sequencing (WGS) confirmed these results for native Swedish populations (those found in the Båven, Emån, and Möckeln water systems). The current project uses the same WGS methods and expands on the previous study by considering samples from non-Swedish populations (river Garonne, France; river Ebro, Spain; hatchery, Czech Republic), as well as improving read-depth coverage and sampling from the introduced Swedish population in the Helge å water system. Both a genome-wide SNP-set and full mitochondrial sequences were used to assess genetic diversity within each population, and differentiation among them. Genetic diversity in Swedish populations is lower than in non-Swedish populations. Native Swedish populations are strongly differentiated from one another. The introduced Helge å population is strongly differentiated from Emån and Möckeln, but less so from Båven. Despite Helge å individuals having heritage that can be predominantly traced to Båven, there are clear signs of admixture with the other two native populations. Swedish populations are all strongly differentiated from the non-Swedish populations. Altogether, evidence of admixture and slightly greater genetic diversity than native Swedish populations in Helge å can at the surface be seen as promising signs. However, it remains uncertain whether these improvements are durable over multiple generations. Considering the poor genetic status of Sweden taken as a whole, and the questionable nature of the improvements seen in Helge å, the long-term viability of Swedish catfish populations remains uncertain.

The effects of aquaculture decline on piscivorous birds in the Mississippi Delta concern catfish farmers with possible increases in fish loss and disease transmission. My study was aimed to (1) develop a new harassment method using unmanned aerial vehicles (UAVs) to effectively control piscivorous birds at fish farms; (2) determine change in spatial distribution of American white pelicans (Pelecanus erythrorhynchos) in the Mississippi Delta since aquaculture decline; and (3) determine third-order habitat selection by the pelicans in the wintering grounds. The UAV harassment did not reduce piscivorous bird abundance more than human harassment in a 2-year field experiment. Aerial surveys demonstrate that the pelicans used natural water bodies to find food more frequently in 2015–2017 than in 1997–1999. Average pelican flock size decreased following the aquaculture decline. Lastly, land cover and land use did not predict fine-scale habitat selection by the pelican.

Channel catfish raising is an important aquaculture in the United States. Mississippi ranks No.1 in catfish production for continuous 4 years. However, catfish fillet processing generates huge amount of by-products, including heads, bone frames, visceras and skins, which contain significant amount of proteins. Removing and utilization of proteins from the by-product would add value to the catfish industry. Collagen was extracted from catfish skin by: (1) acid extraction; (2) homogenization-aided; and (3) pepsin-aided extraction methods. Kinetic analysis of the extraction was performed. SDS-PAGE was performed to analysis the composition of proteins in collagens extracted under different conditions. Collages extracted by three methods was characterized by solubility test, zeta potential, circular dichroism and gel strength. Protein recovery rate from minced skin extracted with pH 2.4 HCl containing 23.6 KU/g pepsin was the highest (64.19%). Papain, ficin, bromelain, neutrase, alcalase, protamex, novo-pro D and thermolysin were used for the hydrolysis of the mixture of heads and frames. Proteolytic activities of these proteases were examined using AzocollTM as a standard substrate. Degree of hydrolysis (DH) of hydrolysates and enzyme reaction kinetics were investigated. Results indicated that thermolysin had the highest activity (82.9×107 AzU/g) at 50 °C when using AzocollTM as the substrate. Ficin (80 AzU/g) was the most efficient in hydrolyzing the proteins in the ground catfish by-product (DH reaching 71.88%) in 120 min at 30°C among all the enzymes. Thermolysin could be used for industries to hydrolyze protein by-products in terms of hydrolysis efficiency and economy. The hydrolysis curves fit the Peleg model very well, all with R2 higher than 0.91. Myofibrillar proteins were extracted from the mixture of heads and frames with different pH conditions, and made into protein gels. Transglutaminase (TGase) was incorporated to improve the gel structure. Solubility and secondary structures of extracted myofibrillar proteins were studied. Gelling properties of the protein sol were studied by dynamic rheological measurement. Physicochemical, textural and thermal properties of protein gels treated with TGase were investigated. Protein pattern changes of TGase treated protein gel was studied by SDS-PAGE. Results indicated that alpha-helicity of myofibrillar proteins decreased with extraction pH over 9. Storage modulus (G’) of protein sol decreased as the increase of extraction pH. Rheological measurement of TGase treated protein sol showed that excessive TGase could weaken the gel structure. This study provides systematic information for the catfish fillet processing industry to utilize the by-products.

Vaccination against intracellular pathogens requires generation of pool of memory T cells, which can respond upon infection and mediate immune responses by either killing of infected host cells or induce killing mechanisms in infected cells. T cell-inducing vaccines aim to deliver the antigen to antigen presenting cells (APCs) by presenting on MHC molecules thus bridging innate and adaptive immunity. The intracellular pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), which is a devastating disease in catfish industry. E. ictaluri can survive in professional phagocytes and use them as an infection source. Two new live attenuated vaccine (LAV) strains, EiDELTAevpB and ESC-NDKL, were developed by our group. However, the role of LAVs in phagocytosis, bacterial killing, and antigen presentation is unexplored. Therefore, further research is necessary to determine immune responses in channel catfish against LAVs. The long-term goal of this project is to identify immunological APC-dependent mechanisms that underscore E. ictaluri pathogenesis to enable development of effective control strategies for ESC. The overall goal of this project is to assess the role of three professional APCs, dendritic cells (DCs), macrophages and B cells in the LAV-induced innate and adaptive immune responses in catfish. The central hypothesis is that efficacious LAV strains will enhance phagocytosis and microbial killing, and promote the generation of T cells that regulate and control protective B cell-mediated immunity. The rationale for this research is that more detailed knowledge about phenotype and function of catfish APCs will not only help gain insight into the evolution of vertebrate adaptive immune system but will provide valuable information for development and optimization of immunotherapies and vaccination protocols for aquaculture use. In this study, we first identified DC-like cells in immune-related organs of catfish and assessed their expression patterns in lymphoid organs of catfish in E. ictaluri infection. Although WT strain induces the functional inability of DC-like cells in migration and maturation, LAVs strains promote the migration and maturation of DC-like cells for antigen presentation. Two LAVs enhanced the phagocytosis and killing activity in catfish macrophages and B cells. Also, LAVs induce high expression of T cell-related genes without causing inflammation.