Food Habits, Occurrence, and Population Structure of the Bull Shark, Carcharhinus Leucas, in Florida Coastal Lagoons

The bull shark, Carcharhinus leucas, is the most common shark in the brackish Indian River lagoon system on the central east coast of Florida. The biology of the lagoon population was studied between May 1975 and May 1979. There was substantial spatial and seasonal variation in catch rates with gill nets. Bull sharks were usually most abundant in the low-salinity lagoon basins. Catch rates were generally highest in the spring and fall and were always higher at night than day. No specimens were netted during the winter although bull sharks are known to be present during that season.

The permanent lagoon population was composed entirely of newborn young and juveniles up to 202 cm TL. As they approach maturity, the subadults leave the estuary. Pregnant adult females return to lagoon waters in late spring and summer to give birth. One pregnant female 249 cm TL was captured during this study. Juvenile bull sharks in the lagoon system fed primarily on stingrays and marine catfishes.