Residency and movement patterns of bonnethead sharks, Sphyrna tiburo, in a large Florida estuary

Abstract

The use of a coastal estuary by bonnethead sharks, Sphyrna tiburo, was examined by acoustic monitoring, gillnet sampling and tag- recapture studies. Acoustic monitoring data were used to define the residency and movement patterns of sharks within Pine Island Sound, Charlotte Harbor, Florida. Sharks were monitored for periods of 1–173 days with individuals regularly moving in and out of the detection range of the acoustic system. Patterns of movement could not be correlated with tidal level or time of day. Home range sizes within the Pine Island Sound population were typically small with individuals using core areas on a daily basis. However, core areas shifted within the study site over time resulting in eventual usage of most of the available habitat. Gillnet sampling revealed that S. tiburo were abundant in shallow water near seagrass beds, but that presence of individuals at specific sites was variable. Tag-recapture data showed that most individuals remained within the Pine Island Sound region over time and did not appear to undergo long coastal migrations. The movement and residence patterns of S. tiburo suggest that individuals are resident within the estuary, but do not show site fidelity to specific areas within the estuary.