Spatial and Ontogenetic Patterns in the Trophic Ecology of Juvenile Bull Sharks (Carcharhinus leucas) From the Northwest Gulf of Mexico

A combination of stomach content and stable isotope (δ 13 C, δ 15 N, 34 S) analyses were used to characterize examine spatiotemporal ontogenetic trends in the feeding ecology juvenile bull sharks ( Carcharhinus leucas ) captured estuaries throughout northwest Gulf Mexico (GoM) between 2013 2016. Shark diets dominated by fish prey taxa [>98% index relative importance (%IRI)], those identified family level, two families comprised greater than 50% IRI, Mugilidae (mullets: ∼32%) Sciaenidae (drums croakers: 27%). Clupeidae (herrings: 14%) Ariidae (sea catfishes: 15%) also contributed substantially diet sharks, though consumption increased as decreased larger 893 mm Fork Length (FL) (∼1 year old). Values N significantly with shark size, indicating a shift toward or higher trophic level increasing size. Latitudinal temporal C S suggest isotopic variation occurred correspondence shifts primary producer assemblages environmental drivers sampled estuaries. These results highlight teleost resources along freshwater-marine continuum well utility natural tracers tracking ecology.