Exploring Legacy Data Sets to Infer Spatial and Temporal Trends in the Ictalurid Assemblage of an Atlantic Slope River

Abstract

The Cape Fear River basin is located along the southeastern Atlantic Slope and is the largest river basin located within North Carolina. Historically, the ictalurid assemblage was characterized by five species of bullhead Ameiurus spp. and three species of madtom Noturus spp. Channel Catfish Ictalurus punctatus were introduced in the early 20th century, followed by Flathead Catfish Pylodictis olivaris in 1965 and Blue Catfish Ictalurus furcatus in 1966. Long-term analysis of the ictalurid assemblage has been confounded by disparate data sets in both electronic and historical paper-based document archives. The goal of this study was to merge contemporary and legacy agency data sets to elucidate spatial and temporal trends in the ictalurid assemblage of the Cape Fear River basin. Rotenone surveys conducted in the 1960s documented abundant madtoms and White Catfish Ameiurus catus throughout the basin. Native species comprised the majority of the ictalurid assemblage through the early 1990s. Since 1990, Blue and Flathead catfish have been the dominant species observed. The largest native ictalurid, the White Catfish, has not been collected since 2008. Nonmetric multidimensional scaling suggests that native ictalurids were more prevalent in small tributaries with increasing distance from the initial adult Flathead Catfish stocking location. Despite the widespread distribution and abundance of nonnative ictalurids, several native species are still found in small tributaries in upstream watersheds. The North Carolina Catfish Management Plan prioritizes the conservation of native ictalurids in the state's Atlantic Slope rivers; however, some species may already be extirpated.