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Systematic descriptions of North American Miocene freshwater fishes are extremely uncommon, with those from the Gulf Coastal Plain region being completely absent. In this study we examined 324 historically collected freshwater fish elements derived from the late Miocene (Hemphillian) Mauvilla fossil site located in Mobile County, Alabama, USA. Analysis of these elements confirmed the presence of three unequivocal taxa including Atractosteus sp. cf. A. spatula, Ictalurus spp., and Aplodinotus grunninens. The preserved elements consisted of spines, pharyngeal bones, pharyngeal teeth, and scales, likely indicating a taphonomic bias towards large individuals with robust elements. The co-occurrence of these three taxa indicate they were derived from a medium-to-large river fish assemblage, suggesting that one or more of the rivers that constitute the nearby Mobile Basin may have been present in the region during the late Miocene. Molecular divergence estimates and morphological similarity to modern representatives both support the presence of these extant taxa in the late Miocene, and the examined remains represent some of the earliest fossil occurrences of these extant taxa. These three taxa also represent the first biogeographic occurrence of each in the late Miocene of both Alabama and the Gulf Coastal Plain of North America and helps to improve our understanding of Miocene freshwater fish assemblages. [ABSTRACT FROM AUTHOR]

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]

Big Prairie Creek, Hale County, Alabama, receives overflow and draining effluent from about 5,000 ha of channel catfish, Ictalurus punctatus, ponds. Tributary streams receiving effluent directly from ponds were higher in concentrations of suspended solids, turbidity, nutrients, and biochemical oxygen demand than Big Prairie Creek, and these variables increased from upstream to downstream stations in Big Prairie Creek. Nevertheless, water quality in Big Prairie Creek was good at the last downstream station, and concentrations of variables did not exceed water quality criteria required by the stream classification system. Six reference streams in the same eco-region as Big Prairie Creek, but without channel catfish farms on their watersheds, had concentrations of most water quality variables similar to those found in the downstream reaches of Big Prairie Creek. Findings suggest that channel catfish farming has not had a great impact on water quality in Big Prairie Creek. Although catfish farms occupy 7.5% of the area of the Big Prairie Creek watershed, stream flow has not decreased as a result of impoundment of runoff by ponds. Use of best management practices (BMPs) to reduce the volume and improve the quality of pond overflow and draining effluents should be adequate to prevent negative downstream water quality impacts in catfish farming areas of Alabama. [ABSTRACT FROM AUTHOR]