Effectiveness of DNA Barcoding for Identifying Piscine Prey Items in Stomach Contents of Piscivorous Catfishes

Introduced predators pose ecological impacts upon prey species and receiving ecosystems. Understanding such ecological interactions creates technical challenges including species-specific identification of partially digested prey items in the stomachs of piscivorous predators. We present the first evaluation of DNA barcoding to identify piscine prey in the stomachs of North American catfishes (Family Ictaluridae). Fish prey items of non-native Blue Catfish Ictalurus furcatus and Flathead Catfish Pylodictis olivaris were obtained by gastric lavage and ranked as lightly, moderately, or heavily digested. We used an established cocktail of universal fish primers (FishF2_t1, FishR2_t1, VF2_t1, and FR1d_t1) to amplify the cytochrome oxidase I (COI-3) region of mitochondrial DNA from these samples. Amplification products were subjected to Sanger sequencing, and edited sequences were compared to entries in GenBank. Eighty-six percent of the sequences generated for lightly or moderately digested samples and 66 % of those for heavily digested samples could be assigned to the species level based on similarity with archived COI-3 sequences. Traditional morphological identification led to species-level identification of 65 % of fish prey items. DNA barcoding resulted in identification to species of 88 % of fish prey items overall. Diet items identified by DNA markers included anadromous Striped Bass Morone saxatilits and herrings and shads Alosa sp that are the focus of fishery restoration programs in these rivers.