Morphological Relationships of Pectoral and Dorsal Spines of Invasive Blue Catfish, Ictalurus furcatus , Over Ontogeny

Blue catfish, Ictalurus furcatus, are an invasive species in the Chesapeake Bay region, known to be opportunistic predators that overlap in habitat with many valuable commercial and recreational native species. The goal of this study was to document dorsal and pectoral spine morphology over ontogeny (ranging in size from 107 to 1054 mm) of this species, and to hypothesize form/function relationships from these data. Fish (n = 36) were collected from the Nanticoke River watershed. Spine length and sharpness were measured for dorsal and pectoral spines, and serration density was documented for pectoral spines. As fish size increases, spine sharpness declines, which indicates significant dulling of spines over ontogeny. Spine length exhibits negative allometry with respect to overall fish size, indicating that spine length does increase over ontogeny but at a slower rate than overall body size. By better understanding the full life history of I. furcatus, we can improve management and eradication efforts of this invasive species.