Pond‐Level Risk Factors Associated with Columnaris Disease on Mississippi Commercial Catfish Farms

Abstract

A large commercial catfish enterprise encompassing over 500 food fish ponds from five farms covering multiple counties in the Mississippi Delta was included in this analysis of columnaris risk factors. A gram-negative bacterium, Flavobacterium columnare, is the cause of columnaris disease and is considered the second-most prevalent bacterial disease in farm-raised catfish. The objective of this study was to determine if pond-level risk factors reported by farm personnel were associated with columnaris disease mortalities. To identify risk factors affecting susceptibility of farm-raised channel catfish Ictalurus punctatus to columnaris disease, a Catfish Management database was developed. Logistic regression was used to model the relationships between probability of columnaris in ponds and risk factors examined. Generalized linear mixed models incorporating hierarchically structured random effects of ponds and one or more fixed-effects risk factors were fitted. In the screening process, each risk factor was evaluated in the basic model as a single fixed-effects factor, and if associated with the outcome (P ≤ 0.20), was retained for development of multivariable models. Two multivariable logistic regression models were constructed from data collected at the pond level by producers. The first was constructed from data in which water quality was not considered. Pond depth and reduced feed consumption for a 14-d period prior to disease outbreaks measured on a per hectare basis were significantly (P ≤ 0.05) associated with columnaris disease. The second, in which water quality variables were also considered, pond depth, reduced feed consumption, shorter intervals from stocking to disease outbreaks, and total ammonia nitrogen were significantly (P ≤ 0.05) associated with columnaris occurrence. This study showed some commonly recorded production variables were associated with columnaris disease outbreaks and, if monitored, could help identify "at risk" ponds before disease outbreaks occur.

Columnaris disease in fish: a review with emphasis on bacterium-host interactions

“…Cunningham et al showed that some commonly recorded production variables (feed consumption, pond depth, ammonia levels and stocking events) were associated with columnaris disease outbreaks and, if monitored, could help identify “at risk” ponds prior to disease outbreaks [116]. Suomalainen et al pointed out that reduction of fish density could be used in the prevention of columnaris disease especially if water temperature is high [105].…”

Flavobacterium columnare: an important contributing factor to fish die-offs in southern lakes of Saskatchewan, Canada

“…3 Opportunistic infection arises when fish are stressed due to suboptimal water conditions, including: increasing water temperatures, high levels of nitrate and/or organic matter, low levels of dissolved oxygen, and high stocking density. 2,3,18,19 Clinical infection is associated with high morbidity and mortality, and is manifested as necrosis of the gills and erosion and ulceration of the skin. Skin lesions typically originate at the base of the dorsal fin and extend ventrally on either side of the body forming a circumferential pale band, creating the classic "saddle back" lesion that is often associated with columnaris disease.…”

Risk Factors Associated with Enteric Septicemia of Catfish on Mississippi Commercial Catfish Farms

“…Hanson et al (2008) found that as pond depth increased, catfish losses from weather-related causes decreased, because the deeper ponds were not as sensitive to windstorms, droughts, and freezing. In contrast, Cunningham et al (2012) found that the incidence of columnaris increased as pond depth increased. Greater pond depth offers more habitat for the catfish; shallower ponds or older ponds that have filled in (Steeby et al 2004) provide less space and may lead to crowding and increased stress on the catfish.…”