Following pioneering laboratory work at Aberdeen University in Scotland, which identified a hydrostatic sensor in sharks, field work was conducted from August through to October 2006 in South Bimini, Bahamas, to investigate the normal hydrostatic pressure range and usage including determining whether Negaprion showed significant changes in depth over time, and how any depth changes related to barometric pressure, daily and tidal cycles. Juvenile lemon sharks <1 m previously fitted with internal acoustic transmitters were used for the study. Generation 5 Data Storage Tags manufactured by CEFAS Technology Limited UK were used and secured externally to the first dorsal of the shark, using an innovative method developed for this study. The DSTs logged both pressure and temperature every 5 seconds for 20 days. During this time observational data was gathered by manual tracking using hydrophone and receiver equipment allowing GPS points to be taken which complemented the DST data. After the 20 days the DSTs were actively retrieved and the data downloaded. Depth profiles have been determined for 6 juvenile sharks and relationships between depth and environmental or meteorological variables, and behaviour patterns of the sharks have been identified.