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The purpose of the present study is to present research data on the propagation of the southern spotted channel catfish.

The channel catfish, Ictalurus punctatus (Rafinesque), was first introduced into Utah Lake in the summer of 1911, and has since been stocked in the lake on numerous occasions. It has only been in the last few years that the channel catfish has become an important game fish in Utah. As the value of the channel catfish, as a game fish, increased, it has become increasingly important to the state to maintain this species for present and future generations. This study was initiated in 1958 and completed in 19 60, and was financed by the Utah State Department of Fish and Game. Data on certain phases of the channel catfish life history were investigated to provide information to aid in management of this species. The following phases were studied: age and rate of growth; age composition of the population; reproduction success; food habits; movements; and extent of the fishing pressure.

Made available in DSpace on 2016-06-02T19:22:51Z (GMT). No. of bitstreams: 1 2451.pdf: 1186476 bytes, checksum: 6ce9892ddca6986185a4680d6f65da6d (MD5) Previous issue date: 2009-06-10 / Financiadora de Estudos e Projetos / Phenol and its derivates are aromatic organic compounds and there are present in the mill, domestic waste and cropscience. Moreover, phenol could induce toxicity in both freshwater and seawater fish and other animals. The aim of this work was evaluating hematological features, intermediary metabolism and muscular and cerebral acetylcholinesterase enzyme activity in juveniles channel catfish Ictalurus punctatus exposed to 1.5 mg L-1 of phenol (10% LC50) for 96 h and after 7 or 14 days of recovery. Ammonia, lactate, piruvate, glucose, amino acids, protein, triglycerides and fatty acids concentrations were measured in liver, muscle and plasma. Glycogen concentration was determined in liver and muscle. Aspartate aminostransferase (ASAT), alanine aminotransferase (ALAT), lactate desidrogenase (LDH), alkaline phosphatase (FALC) and acid phosphatase (FAC) enzymes activities were assayed in liver and muscle. Acetylcholinesterase activity was assayed in white muscle and brain. Hematological features were analyzed through hematocrit, haemoglobin concentration, red cell count (RBC), mean corpuscular volume (VCM), mean corpuscular haemoglobin (HCM) and mean corpuscular haemoglobin concentration (CHCM). Hematological alterations were observed after 7 days of recovery. After 96 h, ALAT and ASAT activities and protein concentration indicated proteolysis liver and muscle. The triglycerides and fatty acids concentration suggested lipolysis in muscle. The results also indicated gluconeogenesis in liver. Gluconeogenesis follows over 7 days of recovery and glycemia was kept constant. After 7 days of recovery, the results suggested proteolysis and lipolysis in liver. After 14 days of recovery, the results indicated glycogenolysis and muscle and liver. Reductions of protein and amino acid concentrations plus ASAT activity rising in muscle, also suggested proteolysis. Alterations in FAC and FALC activities in muscle and liver were observed. These results suggest membrane cell damage. Reduction in cerebral AChE activity was observed after 14 days recovery. In other hand, an increase of muscular AChE was observed after 7 and 14 days recovery. In conclusion, the alterations observed in this work seem to be due to increased metabolic demand and other mechanisms that respond to homeostasis in fish. / O fenol e seus derivados são compostos orgânicos aromáticos provenientes de efluentes industriais, domésticos e de práticas em agricultura. São encontrados tanto em corpos de água doce como em salgada e podem induzir toxicidade aos animais expostos. Os objetivos deste estudo foram avaliar os efeitos da exposição sub-letal ao fenol (1,5 mg L-1 ou 10% da CL50) sobre as variáveis hematológicas e metabólicas de juvenis do bagre do canal (Ictalurus punctatus) após 96 h de exposição e recuperação por 7 e 14 dias. No fígado, no músculo e plasma foram quantificados amônia, lactato, piruvato, glicose, aminoácidos livres, proteína, triglicerídeos e ácidos graxos. O teor de glicogênio foi determinado no fígado e músculo. Atividade das enzimas alanina aminotransferase (ALAT), aspartato aminotransferase (ASAT), lactato desidrogenase (LDH), fosfatase ácida (FAC) e fosfatase alcalina (FALC) foram ensaiadas no músculo branco e fígado. A acetilcolinesterase (AChE) foi ensaiada no cérebro e no músculo branco. As variáveis hematológicas avaliadas foram hematócrito, conteúdo de hemoglobina e contagem de células vermelhas (RBC), volume corpuscular médio (VCM), hemoglobina corpuscular média (HCM) e concentração de hemoglobina corpuscular média (CHCM). Alterações hematológicas foram observadas após 7 dias de recuperação. Após 96 h de exposição, as atividades da ASAT e ALAT hepática e muscular e a concentração de proteína indicaram proteólise nestes tecidos. No músculo, verificou-se lipólise muscular. No tecido hepático, os dados são sugestivos de gliconeogênese. Após 7 dias de recuperação, os resultados indicaram proteólise, lipólise e persistência dos processos gliconeogênicos. Após a recuperação por 14 dias, observou-se glicogenólise muscular e hepática, assim como proteólise muscular. Alterações nas atividades das fosfatases ácida e alcalina foram sugestivas de possíveis danos nas membranas celulares. A atividade da enzima AChE cerebral apresentou-se reduzida após recuperação por 14 dias. No músculo, observou-se aumento na atividade desta enzima na recuperação por 7 e 14 dias. Estes resultados indicam que as alterações observadas parecem ocorrer devido ao aumento da demanda metabólica e de outros mecanismos que respondem pela homeostasia do animal frente ao fenol ambiental.

Myxozoans are cnidarian parasites of primarily freshwater and marine fish, with some being important pathogens of aquacultured fish species worldwide. Their life cycles have waterborne actinospores released from aquatic annelid definitive hosts and myxospore stages in fish intermediate hosts. In the southeastern United States, catfish aquaculture is burdened by annual losses to a myriad of infectious diseases. Henneguya ictaluri, the causative agent of proliferative gill disease in channel catfish Ictalurus punctatus and female channel catfish x male blue catfish Ictalurus furcatus hybrids, is the most commonly diagnosed parasitic disease of catfish in Mississippi. Other myxozoans infect these ictalurid fish, but their impact on catfish production is unknown. Surveys of actinospores from the oligochaete Dero digitata and myxospore stages from fish revealed an unexpected diversity for these production systems. Six genetically distinct actinospores representing four collective groups were observed from D. digitata. Herein, two novel Henneguya spp. are described from the gills and a novel Unicauda sp. is described from the intestinal tract of channel catfish. One Henneguya sp. was linked to its actinospore stage and represents the fourth known life-cycle in the genus. In addition to catfish, smallmouth buffalo Ictiobus bubalus polycultured with catfish were examined and two Myxobolus spp. were characterized from the gills. Phylogenetic analyses strongly support a clade of ictalurid Henneguya spp. and a clade of catostomid Myxobolus spp. Although diverse, H. ictaluri is the only myxozoan in catfish attributed to significant losses. With no feasible method of control or treatment, investigations into less susceptible fish were initiated and showed promise. Infectivity trials characterizing H. ictaluri development in channel, blue, and hybrid catfish were performed. Channel catfish were suitable hosts with myxospores developing in the gills by six weeks and persisting for at least 14 weeks. In hybrid catfish arrested or limited development was observed with no pseudocysts observed during Trial 1 and only two at 14 weeks during Trial 2. These results may suggest a possible way of decreasing losses attributed to PGD through hybrid catfish monoculture or fish crop rotation to reduce the number of infectious myxospores released into the pond.

Red fillet results in a profit loss for catfish processors and producers alike; however, neither the cause nor the abundance of red fillet has been studied extensively. Therefore, an assessment of red fillet in the catfish industry was conducted along with studies subjecting catfish to poor water quality and inoculation with Aeromonas sobria. Within every catfish harvest, 0.12% of fillets were rejected due to blotchy red coloration. Histology revealed congestion of erythrocytes indicating internal hemorrhaging, and A. sobria was isolated from 63% of all red fillets compared to 28% of acceptable fillets. Acute exposure to poor water quality did not produce red fillet in catfish despite high stress levels and mortality rates (22%). Inoculation with A. sobria did induce red fillet with similar coloration to red fillets obtained from catfish processors.

Aeromonas hydrophila is a Gram-negative, rod shaped, facultative anaerobic bacterium that is ubiquitous to freshwater and slightly brackish aquatic environments and can cause infections in fish, humans, reptiles, and avian species. Recent severe outbreaks of disease in catfish aquaculture have been associated with a highly virulent Aeromonas hydrophila strain (VAH) that is genetically distinct from less virulent strains. Given that A. hydrophila is known to infect birds, we hypothesized that fish eating birds may serve as a reservoir for VAH and spread the pathogen by flying to uninfected ponds. Great Egrets were used in this transmission model because these wading birds frequently predate catfish farms. We found that Great Egrets that were fed VAH infected catfish shed VAH demonstrating their potential to spread VAH. Histologically there were changes found in selected tissue samples.

Since being first reported in the late 1980ies, the Enterobacterium Edwardsiella ictaluri has rose in prevalence to become one of the two most damaging pathogens affecting the channel catfish industry. Despite this significance of the pathogen, understanding of the development of the disease, especially its route of entry into the host and the earlier stages of the infection, is still incomplete. A series of challenges were conducted using bioluminescent E. ictaluri either by infecting fish through immersion or topical application of the bacteria directly on the intact or abraded epithelium. This showed that abraded fish developed septicemia and died faster than non-abraded ones. Furthermore, results from a co-habitation challenge suggested that the bacterium induced septicemia through the skin instead of becoming water-borne. Finally, a histological technique was developed allowing the determination that the bacteria radiated from the initial skin infection site and penetrated deeper into the tissue as the challenge progressed. These results all suggest that site of abrasion on the skin can act as a route of entrance for the pathogen into the fish, a fact never previously reported. Transposon mutagenesis was also performed to construct a library of 1728 mutants. Screening of this library allowed us to identify 16 genes which inactivation lead to a decrease in the bacterium ability to colonize the epithelium or cause mortality. Sequencing of these genes allowed the identification of RstA/B, a regulator of invasion genes in Salmonella enterica Typhimurium, a putative ribonuclease, similar to a Shigella protein regulating the expression of adhesin and a protein that constitutes the second member of a newly discovered adhesin family. Finally, to investigate the development of the infection, fish were infected by bioluminescent E. ictaluri and sampled at various time points. At each time point, nine organs (gills, muscles, intestine, spleen, liver, stomach, heart, head kidney and trunk kidney) were sampled, and their bioluminescence was measured and half of these organs were homogenized, serial diluted, and plate counts determined. This allowed confirmation of a complex disease pathogenesis during ESC involving a period of intense reproduction in the spleen, anterior and posterior kidneys followed by a sharp increase in the levels of bacteria in the blood.

Acoustically, teleost swimbladders have been considered resonant underwater bubbles. Contrary results indicating that bladders are tuned less sharply than such a bubble have been explained by damping of surrounding fish tissue. Recent findings in toadfish and weakfish, however, suggest that the bladder is a highly damped structure and that the frequency of the fish sounds is deternlined as a forced response to sonic muscle movement rather than by resonance of the bladder. In this study I examined acoustics and material properties of swimbladders in Tilapia (an auditory generalist) and the channel catfish (an auditory specialist). The swimbladder was struck with a piezoelectric impact hammer. Amplitude and timing characteristics of bladder sound and displacement were compared for strikes of different amplitudes. Most of the first cycle of sound occurs during swimbladder compression, indicating that the bladder rapidly contracts and expands as force increases during the strike. Harder hits are shorter in duration generate a similar displacement duration with an increasing number of shorter cycles and a 12-15 dB increase in sound amplitude. The frequency spectrum is broad, and the dominant frequency is driven by the strike and not the natural frequency of the bladder. The displacement waveform varies between species catfish exhibit a greater structural stiffness and lower amplitude movement and higher sound amplitude for an equivalent hammer strike. Material properties (peak load, stress, strain, Young's modulus), fiber direction (catfish only), and structural stiffiless of bladders exhibit various patterns suggesting that the bladder walls are not uniform structures. Additionally thickness varies regionally. Notably Young's modulus in both species is similar despite large difference in stress and strain. The modulus of catfish bladder increased 1600-fold when dried. Finally the bladder of both species had a high water content averaging about 70%. These data suggest that viscous damping caused by water in the bladder wall is a major factor responsible for acoustic properties of the teleost swimbladder.

The commercial production of channel catfish (Ictalurus punctatus) is major industry in Mississippi. Infections of channel catfish with the digenetic trematode Bolbophorus damnificus have often been associated with heavy economic losses in the industry. To efficiently control transmission of this trematode, the avian hosts need to be identified. In the first study, two American white pelicans, two double-crested cormorants, two great blue herons, and two great egrets were fed channel catfish infected with B. damnificus metacercariae. The presence of Bolbophorus damnificus ova in pelican feces at three days post infection (dpi) indicated the pelicans had patent infections. Mature B. damnificus were recovered from the intestines of both pelicans at 21 dpi. No B. damnificus infections were observed in the other bird species. In a second study, 33 American white pelicans, 34 double-crested cormorants, 35 great blue herons, and 32 great egrets were collected in the Mississippi Delta. The prevalence of B. damnificus in the American white pelican was 93.9%, with an average of 158 B. damnificus found per bird (range 0-681). Bolbophorus damnificus was not found in any of the other bird species. The results of these two studies confirm that the AWPE is the only proven natural host for B. damnificus. In a third study, two previously undescribed cercariae were found infecting rams-horn snails in commercial catfish ponds. In challenge studies, channel catfish were exposed to both cercariae types. Only one type of cercariae (type I) was infective to channel catfish. The first evidence of type I metacercariae was seen histologically at 14 dpi and grossly at 21 dpi. Development continued until 120 dpi, when both gross examination and histology suggested that the metacercariae were mature. The type I metacercariae appeared to cause little host damage. Molecular analysis of the 18S rRNA gene region indicated that the type I cercariae and metacercariae may be a species of Clinostomum. The data generated in these three studies provides additional information that can be used in the development of efficacious management schemes to control digenetic trematodes infecting commercial catfish.