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In 2009, a virulent strain of Aeromonas hydrophila caused severe disease and high mortalities (motile aeromonad septicemia variant [MASv]) in farmed channel catfish (Ictalurus punctatus) and hybrid catfish (I. punctatus × I. furcatus) in eastern Mississippi and Alabama. As is common in MAS, there is severe hemorrhagic dermatitis with ulceration, as well as abdominal hyperemia, petechiation, and mild ascites. Additional findings in MASv cases include panophthalmitis and orbital cellulitis, leading to ocular rupture, and brains are often hyperemic with mild random acute hemorrhage. In MASv infections, there is consistently also marked hemorrhage and edema in the submucosa and muscularis of the stomach, with lymphangitis and a few bacteria, plus splenomegaly with infarcts. Microscopically, spleens have necrosis of ellipsoids with macrophage infiltration and small numbers of bacteria; however, large infarcts are filled with bacteria. Other organs, such as liver, kidneys, and intestine, which are typically associated with MAS caused by various aeromonad species, are less affected. The findings in the stomach have not been reported in MAS in farmed catfish, to our knowledge, and the splenic changes are highly characteristic of MAS compared to infection with other gram-negative bacteria, including Edwardsiella ictaluri and other aeromonad species and strains. [ABSTRACT FROM AUTHOR]

Management of Blue CatfishIctalurus furcatusand Channel CatfishI. punctatusfor trophy production has recently become more common. Typically, trophy management is attempted with length-based regulations that allow for the moderate harvest of small fish but restrict the harvest of larger fish. However, the specific regulations used vary considerably across populations, and no modeling efforts have evaluated their effectiveness. We used simulation modeling to compare total yield, trophy biomass (Btrophy), and sustainability (spawning potential ratio [SPR] > 0.30) of Blue Catfish and Channel Catfish populations under three scenarios: (1) current regulation (typically a length-based trophy regulation), (2) the best-performing minimum length regulation (MLRbest), and (3) the best-performing length-based trophy catfish regulation (LTRbest; “best performing” was defined as the regulation that maximized yield,Btrophy, and sustainability). TheBtrophyproduced did not differ among the three scenarios. For each fishery, the MLRbestand LTRbestproduced greater yield (>22% more) than the current regulation and maintained sustainability at higher finite exploitation rates (>0.30) than the current regulation. The MLRbestand LTRbestproduced similar yields and SPRs for Channel Catfish and similar yields for Blue Catfish; however, the MLRbestfor Blue Catfish produced more resilient fisheries (higher SPR) than the LTRbest. Overall, the variation in yield,Btrophy, and SPR among populations was greater than the variation among regulations applied to any given population, suggesting that population-specific regulations may be preferable to regulations applied to geographic regions. We conclude that LTRs are useful for improving catfish yield and maintaining sustainability without overly restricting harvest but are not effective at increasing theBtrophyof catfish. Received February 1, 2016; accepted June 16, 2016 [ABSTRACT FROM AUTHOR]

We performed a field experiment in five eastern South Dakota lakes to investigate fish escapement differences between modified fyke nets with two common throat configurations (restricted and unrestricted). Nets with restricted and unrestricted throats were deployed in pairs for 24 h on similar habitat. Captured fish were measured for TL and were given day-specific marks. The paired nets were redeployed, and marked fish were randomly assigned to be stocked into the restricted or unrestricted net for 24 h; stocking densities (stratified into low, medium, and high) were species specific. Marked fish that were retained after 24 h were used to quantify escapement, whereas newly captured fish were used to estimate differences in mean CPUE and size structure. Mean CPUE of Black BullheadsAmeiurus melas, Black CrappiesPomoxis nigromaculatus, and BluegillsLepomis macrochirusapproximately doubled when restricted nets were used. Mean TL of Black Crappies was 31 mm greater (95% confidence interval [CI] = 6–57 mm greater) and mean TL of Bluegills was 21 mm greater (95% CI = 8–35 mm greater) in restricted nets than in unrestricted nets. Escapement from restricted nets was 4.4% for Black Crappies and 10.3% for Bluegills, whereas escapement from unrestricted nets was 71.7% for Black Crappies and 58.4% for Bluegills. We urge researchers to consider the influence of varying fyke-net throat configurations on calculated population metrics, and we recommend inclusion of the restricted throat feature in gear specifications for North American standard modified fyke nets. Received April 6, 2015; accepted October 14, 2015 [ABSTRACT FROM PUBLISHER]

The article discusses a study which evaluated in vivo the adhesion dynamics of Flavorium columnare to fish tissues such as that of catfish Ictalurus punctatus. Scanning electron microscopy (SEM) was used to observe gill-adhered bacterial cells after immersion challenge, bacterial plate count and confirmation. The study found that particular strains of Flavobacterium columnare exhibit different levels of specificity to their fish hosts, and that adhesion to fish tissues is not sufficient to cause columnaris disease.

The article presents a study on the pathological changes in channel catfish or Ictalurus punctatus that is spontaneously infected by Streptococcus iniae. The researchers gathered about 200 diseased channel catfish from a commercial aquaculture farm in Guangxi province in China, which were affected by a streptococcosis outbreak. They also examined the body surface and gills microscopically for the presence of parasites. They found that Streptococcus iniae has emerged as a very important bacteria infecting warm water fish and aquaculture animals, which leads to major economic losses across the world.

The article discusses a study on Icalurus punctatus, a pond-reared channel catfish with proliferative gill disease (PGD) caused by Henneguya species, a myxozoan parasite, using light and transmission electron microscopy, to characterize the inflammatory response during infection. In the study, the early lesions lacked inflammatory response around the disrupted cartilage, a chondrocyte response was not apparent, and the parasite was not present, indicating that the cartilage breaks occur before inflammation and arrival of the parasite in the gill. The study concluded that other chondrocytes in the lesions had ultrastructural features suggesting cell death.

The article discusses a study which investigated the association between improved body condition and superabundant food at catfish aquaculture facilities in American White Pelicans (Pelecanus erythrorhynchos). The study was conducted in four geographic regions in Mississippi and Louisiana. It was observed that Pelicans that foraged on catfish during spring have better physical condition.

The channel catfish Ictalurus punctatus is a popular sport fish commonly maintained by annual stocking in small impoundments. We sought to determine whether channel catfish negatively affect two other sport fishes (bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides) in Alabama's state public fishing lakes (ASPF lakes) through competition or predation. Using a variety of gears, we sampled channel catfish, largemouth bass, and bluegills in 12 ASPF lakes with variable channel catfish stocking and harvest rates. Four of these lakes were sampled more intensively to quantify the diets of these three species. Bioenergetics simulations were used to predict the annual consumption of channel catfish and largemouth bass populations of average density, size structure, and growth from these impoundments. Metrics of growth, condition, abundance, and population structure were not related between species. Latitude was negatively related to channel catfish growth. The diets of channel catfish and bluegills were moderately similar across all seasons in all lakes, while those of channel catfish and largemouth bass were highly dissimilar. Within species, diet similarity was high among lakes. Bioenergetics simulations suggest that the channel catfish populations in these lakes consume relatively little fish, particularly when compared with a typical largemouth bass population. We found little evidence of negative effects of channel catfish on the bluegill and largemouth bass populations in ASPF lakes, although largemouth bass growth and condition were poorest in the lake with the highest channel catfish stocking rate. However, current stocking and exploitation rates in most lakes appear to maintain channel catfish abundance below the level at which negative effects may occur. [ABSTRACT FROM AUTHOR]

Sagittal otoliths and the articulating process of the pectoral spine have both been validated as accurate techniques for estimating the age of channel catfish Ictalurus punctatus (≤age 4). However, there is limited information on the relative precision of estimates from these two structures. Thus, we analyzed the precision of age estimates derived from otoliths and the articulating process of the pectoral spine and compared the dynamic processes (recruitment, growth, and mortality) resulting from those estimates. Aging structures were removed from 110 channel catfish captured from the Wabash River (river kilometers 550-9.6) via day--time electrofishing. The age estimation methodologies were similar to those described in previous studies. Agreement between the ages derived from the two structures was high: the average percent error was 8.4%, the coefficient of variation was 11.4, and the slope of the age bias plots did not differ from 1, indicating similar age assignments between structures. The corresponding recruitment patterns, von Bertalanffy growth models, and mortality rates did not differ between the aging structures. We conclude that the articulating process of the pectoral spine provides age assignments similar to those of otolighs and that the dynamic processes do not differ between structures. Further, based on the results of this study, the articulating process of the pectoral spine provides a suitable alternative to otoliths and has the advantage that channel catfish do not have to be sacrificed. [ABSTRACT FROM AUTHOR]

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

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

This report presents data from one of the largest standardized stream surveys conducted in the western United States, which shows that one of every four individual fish in streams of 12 western states are nonnative. The states surveyed included Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. The most widely distributed and abundant nonnative fishes in the western USA were brook trout Salvelinus fontinalis, brown trout Salmo trutta, rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio, smallmouth bass Micropterus dolomieu, largemouth bass M. salmoides, green sunfish Lepomis cyanellus, fathead minnow Pimephales promelas, yellow perch Perca flavescens, yellow bullhead Ameiurus natalis, cutthroat trout O. clarkii, western mosquitofish Gambusia affinis, golden shiner Notemigonus crysoleucas, channel catfish Ictalurus punctatus, and red shiner Cyprinella lutrensis. The greatest abundance and distribution of nonnative fishes was in interior states, and the most common nonnatives were introduced for angling. Nonnative fishes were widespread in pristine to highly disturbed streams influenced by all types of land use practices. We present ranges in water temperature, flow, stream order, riparian cover, human disturbance, and other environmental conditions where the 10 most common introduced species were found. Of the total western U.S. stream length bearing fish, 50.1% contained nonnative fishes while 17.9% contained physical environment that was ranked highly or moderately disturbed by humans. Introduced fishes can adversely affect stream communities, and they are much more widespread in western U.S. streams than habitat destruction. The widespread distribution and high relative abundance of nonnative fishes and their documented negative effects suggest their management and control should elicit at least as much attention as habitat preservation in the protection of native western U.S. stream biota. [ABSTRACT FROM AUTHOR]

We related the length at age of channel catfish Ictalurus punctatus, an indirect measure of growth, to three climatic and five morphoedaphic variables in 144 Texas reservoirs. Growth of channel catfish ages 3 through 6 was negatively related to longitude, a factor that explained as much as 34% of the variation in length at age. Channel catfish length at age was not significantly related to latitude, conductivity, morphoedaphic index, mean depth, and maximum depth in all age-classes. Among age-7 channel catfish, length at age was positively related to reservoir area, which explained 35% of the variation in growth. A quadratic model for growing-season length explained 7-17% of the variation in length at age in all age-classes. Overall, length at age for channel catfish was greatest in reservoirs with intermediate growing seasons (approximately 270 d in length) and was lower when the growing-season length was either longer or shorter. Our results provide the first evidence that the length of growing season on a statewide or regional scale may affect the growth of channel catfish. [ABSTRACT FROM AUTHOR]

A northern population of channel catfish Ictalurus punctatus was assessed to ascertain the abundance and demographics of the population. Standardized trap-netting was conducted from 1997 to 2002 in six reaches of the Ottawa River. A total of 13,197 channel catfish were sampled. The relative stock density was 18.5% stock, 47.7% quality, 27.2% preferred, 4.4% memorable, and 0.5% trophy. Mean relative weight was 71 for all channel catfish combined and for the different size-classes it was 37 for stock, 61 for quality, 88 for preferred, 133 for memorable, and 120 for trophy. Growth was slow compared with that of more southerly populations but longevity was greater (ages of up to 26 years). Annual mortality was 15.7%. Population estimates ranged from 38,445 to 220,924 in the various reaches, and density ranged from 3.5 to 31.7/ha. Channel catfish are an abundant and underutilized species in the Ottawa River; however, given their life history traits, this fishery is susceptible to overexploitation. [ABSTRACT FROM AUTHOR]

Presents a study that evaluated the perceived decrease in trophy channel catfish Ictalurus punctatus in Brownlee Reservoir and the Snake River, Oregon. Angler exploitation rate for catfish in the river; Background on the study site; Estimation of the movement of fish in the reservoir and river.

The problem of invasive species of fish is a major issue, both internationally and nationally. The presence of invasive species is often associated with acclimatization of new species of fish, activities correlated with the absence of effective control and quarantine programs. In other words, when new desired species are imported, other accompanying species are also brought in often in the form of embryonated eggs or juveniles. The brown bullhead, which we have studied, is also an invasive species of fish in Stejeris Lake, Cluj County. This species is of interest, both scientifically and economically. From the scientific point of view, brown bullhead has a high capacity of resistance to environmental changes, unfavourably conditions, which ensures a perpetuation of the species in almost every aquatic environment. Even though it is recognized that the economic impact of this invasive species is significant, not much information is available at present, and neither is there much data about the topography of its internal organs, which is being studied in this paper. [ABSTRACT FROM AUTHOR]