Movement and Distribution of Juvenile Bull Sharks, Carcharhinus leucas, in Response to Water Quality and Quantity Modifications in a Florida Nursery

Movement, distribution, and habitat use of juvenile bull sharks were examined in two studies using manual and passive acoustic telemetry. Research was conducted in the Caloosahatchee River, which serves as nursery habitat for this species, and is highly impacted due to anthropogenic alterations in water quality and quantity via dams and locks. Manual tracking yielded fine-scale results for eight individuals on home range size, rate of movement, swimming depth, linearity, direction of travel, tidal influence, diel pattern, as well as correlation with environmental variables. Changes in salinity, temperature, dissolved oxygen, turbidity, and pH played a role on the distribution of bull sharks. Passive monitoring of twelve individuals allowed for examination of trends in residency, home range, depth, and distribution in response to water quality alterations. Both studies documented a shift in the distribution of animals in response to significant modifications in salinity and flow levels. Sharks were distributed throughout the river at low flow rates, but were located only near the river mouth, or exited the river at discharges rates above 75 m³s-1. Current water management policies are examined and recommendations are made which include the physiological preferences of this top-level predator