|Fish health assessments were made between impinged and reference fish collected at and in the vicinity of Steam Plant Gorgas (Black Warrior River, Walker County, Alabama) during three seasons: spring/summer, fall, and winter/spring as well as two additional plants during the fall sampling season: Steam Plant E.C. Gaston (Lay Lake, Coosa River, Shelby County, Alabama) and Steam Plant Greene County (Black Warrior River, Greene County, Alabama). The three species investigated for fish health assessments included gizzard shad (Dorosoma cepedianum), threadfin shad (Dorosoma petenese), and freshwater drum (Aplodinotus grunniens). Assessments were based on body weight-length, external lesions, and pathogen detection. Freshwater drum were aged using otoliths at Plant Gorgas. Impinged gizzard shad, threadfin shad, and freshwater drum weighed significantly less when compared to reference fish during all three seasons at Plant Gorgas. Lesions were significantly more common in impinged compared to reference gizzard shad and freshwater drum during the spring/summer season and in impinged compared the reference threadfin shad during the winter/spring season at Plant Gorgas. Aeromonas hydrophila and internally isolated and lesion associated Flavobacterium columnare was detected in significantly higher percentage of impinged compared to reference gizzard shad during all seasons, and in impinged compared to reference threadfin shad during the winter/spring season. Aeromonas veronii biotype sobria was detected in significantly higher percentage of impinged than in reference gizzard shad during the fall season. The protozoan parasite, Ichthyobodo necator, was observed in higher prevalence in impinged gizzard shad compared to reference during the fall season and in impinged freshwater drum compared to reference during the spring/summer and winter/spring seasons. It was determined that there was no significant difference in age between impinged and reference freshwater drum at Plant Gorgas.
Length-weight analysis and lesion associated and internal F. columnare was determined to be significant in impinged compared to reference freshwater drum at Plant Greene County. None of the components of the overall disease analysis were concluded to be significant at Plant E.C. Gaston. This could be attributed to small sample size. The results of this study indicates that intake screens at steam generating power plants may be selectively impinging sick, dead, and dying fish.