The diet of juvenile and mature lemon sharks in the southeast United States

Abstract The lemon shark ( Negaprion brevirostris ) is a coastal species found in a variety of nearshore marine ecosystems in the Western Atlantic Ocean. Although studies on the diet of juvenile lemon sharks are common, little information on the diet of larger juveniles and mature lemon sharks has been reported. To investigate the diet of larger juvenile and mature lemon sharks, we analyzed stomach contents of 67 lemon sharks (179 to 270-cm fork length) collected between 2011 and 2018 along the South Atlantic and Gulf Coasts of the United States. Of the 67 stomachs examined, 53 (79.1%) contained prey. Based on % index of relative importance (IRI), a cumulative index, larger juvenile and mature lemon sharks sampled fed primarily on teleost fish (78.0%) and mollusks (15.1%). Of these two categories, family Octopodidae had the highest %IRI (48.0%) followed by families Carangidae (jacks) (3.8%) and Lutjanidae (snappers) (1.9%). The next most common prey category was elasmobranchs (6.2%). The diet of larger juvenile and mature lemon sharks in our study differs from the diet of young lemon sharks, which consists of nearly all fish and crustaceans, indicating that these sharks demonstrate ontogenetic shifts in their diet. The broader diet of larger juvenile and mature lemon sharks likely reflects expanded movements, occupancy of increasingly variable environments and more frequent encounters with diverse prey as they age and increase in size. Ontogenetic changes in the diet of animals illustrate the importance of sampling a broad range of sizes and individuals from a variety of habitats to understand ecological interactions of a species across the size range and within multiple habitats occupied.