Ontogenetic diet shifts and prey selection in nursery bound lemon sharks, Negaprion brevirostris, indicate a flexible foraging tactic

Ontogenetic variations in shark diet are often qualitatively inferred from dietary analysis and hindered by high levels of unidentified prey or small sample sizes. This study focused on nursery bound lemon sharks (Negaprion brevirostris, n?=?396), enabling some control over the confounding variables of prey choice associated with ontogeny. Nursery bound lemon sharks exhibited weak ontogenetic variation in dietary composition with high levels of dietary overlap. Variation in prey preference of lemon sharks with ontogeny was complex, but revealed a continuous shift from predominantly opportunistic benthic foraging as neonates to more selective piscivory with increasing shark size while in the nursery. Lemon sharks demonstrated a discrete ontogenetic shift in the number of prey consumed and stomach content weight (Kruskal-Wallis tests p?p?p?Gerres cinereus), suggests neonate sharks, while capable of occasionally foraging on large prey, are relatively inept opportunistic foragers. This was evident in high diet breadth, low diversity of consumed prey and lower trophic level than larger sharks. This study represents the first quantitative analysis of ontogenetic variation in prey preference and size selection in sharks, indicating a flexible foraging tactic in lemon sharks and the importance of hunting ability and predator size in prey choice.