Feeding and Trophic Ecology of Invasive Blue Catfish (Ictalurus furcatus) in the Nanticoke River, Chesapeake Bay

Abstract

Blue Catfish Ictalurus furcatus were introduced into Western Shore tributaries of the Chesapeake Bay in the 1970s to provide fishing opportunities and are now classified as an invasive species due to their negative economic and ecological impacts. By the 2000s, these invasive ictalurids expanded into tributaries along the Eastern Shore, which possess unique ecological characteristics, potentially driving local differences in the feeding and trophic ecology of invasive Blue Catfish. As opportunistic, generalist feeders, variability in prey availability may be evident in the diet of Blue Catfish. This study investigates the diet composition and trophic interactions of Blue Catfish in the Nanticoke River watershed, on the Chesapeake Bay’s Eastern Shore, using stomach content and stable isotope analyses. Stable isotope analysis of carbon, nitrogen, and sulfur in bulk muscle tissue suggest that Blue Catfish consume marine-derived nutrients and feed at a high trophic level. However, effluent from wastewater treatment plants and agricultural sources may influence δ15N and δ34S values. Stomach contents from Blue Catfish (n = 557) reveal size-based variability in prey and moderate local differences in diet composition compared to other Atlantic slope tributaries. Blue Catfish >350mm total length frequently preyed on seasonally available economically and ecologically significant species, including river herring Alosa spp., blue crab Callinectes sapidus, White Perch Morone americana, and Atlantic Menhaden Brevoortia tyrannus. These ecological insights inform fisheries management of invasive Blue Catfish and prey species on the Eastern Shore of the Chesapeake Bay.