Using DNA barcoding to improve taxonomic resolution of the diet of red snapper (Lutjanus campechanus) along the Atlantic coast of the southeastern United States

Predator–prey interactions are a vital yet often under-studied regulator of marine fish population and community structure. However, fish prey species often cannot be identified by using morphological characters because of degradation from digestion. Consequently, diet is often poorly known for piscivorous predators. The study described here combined visual inspection and molecular diet analysis to increase taxonomic resolution for prey found in stomachs of red snapper (Lutjanus campechanus) (number of stomachs [n]=105) along the Atlantic coast of the southeastern United States. Overall, the diet of red snapper from this region was diverse with 42 invertebrate and 28 vertebrate taxa identified. Broadly, shrimp were the most important prey consumed according to indices of relative importance (39.95%), followed by fish (34.38%), and crab (19.04%) species. In total, 19 fish prey species were identified by using DNA barcoding, compared with 2 species identified when visual methods alone were used. Results of the use of increased taxonomic resolution do not indicate significant predation by red snapper on other managed fish species in the snapper-grouper complex, indicating that the rebuilding stock of red snapper in the region is not affecting other managed species through direct predation.