Masters Student
Jasmine Nyce

Bull sharks (Carcharhinus leucas) occur circumglobally and inhabit coastal environments in tropical, sub-tropical, and temperate regions. They are a euryhaline species, meaning they can inhabit saltwater, estuarine, and freshwater environments. At birth, they are 44-54 cm FL and reach maturity at 184 cm FL and 196 cm FL for males and females, respectively (Natanson et al. 2014). Bull sharks have a “K-selected” life history as large-bodied organisms, meaning they grow slowly and mature late. Therefore, a multi-year study is needed to determine trends and make suggestions for the management and conservation of the species. ​

 

Acoustic telemetry research has previously and continues to provide long-term movement, habitat use, and various other ecological data on many aquatic and marine species. The data collected by these tags are transmitted via acoustic receivers and do not rely on recapturing the animal to understand its movement. This research will utilize acoustic telemetry technology using internal transmitters lasting up to 10 years. Tagging efforts will be focused on Florida waters for the duration of the current study. By working with collaborators, the new tags will be accompanied by historical data to create a long-term data set. The analysis will encompass over a decade of detection data of bull sharks mainly by utilizing collaborative acoustic networks, such as the Ocean Tracking Network (OTN), Florida Atlantic Cooperative Telemetry (FACT) network, Atlantic Coastal Telemetry (ACT) array, and iTag cooperative telemetry network. ​

 

Species movement ecology and seasonal abundances are essential for fisheries management plans and effectively designing marine protected areas. This research focuses on large predators who serve an important role in shaping and maintaining a healthy marine ecosystem through consumptive impacts and influencing the behavior of prey species (Heithaus et al. 2012). Bull sharks have historically had a negative reputation because of their interactions with humans through direct contact or the fishing community. Since they inhabit coastal ecosystems, interactions have increased with a growing population utilizing coastal areas. This has led to backlash directed at bull sharks, resulting in fishing tournaments to remove them from the ecosystem. The National Marine Fisheries Service (NMFS) has not formally evaluated bull shark stocks. Still, given their life history traits, there is potential for overfishing of the species. Many previous studies on this species have been focused on juvenile sharks (Yeiser et al. 2008, Ortega et al. 2009, Heupel et al. 2010, Drymon et al. 2014, Matich & Heithaus 2014, Strickland et al. 2019). Therefore, there is a need for more comprehensive research on adults of this species, particularly their movements, behavior, and habitat use.​

 

This research aims to determine adult bull sharks' spatial and temporal patterns, movement speed, and frequency in the Bahamas, the Florida Keys, the Southeastern USA, and the Gulf of Mexico (GOM). We will also utilize ultrasound technology to assess large females' reproduction status before tagging to determine if there are connections to known nursery grounds. Knowledge of bull shark movements would provide information on where these sharks are throughout the year, whether bull sharks in the GOM and Eastern Florida are a single mixed stock or two distinctive stocks, and their overlap with commercially important species.