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The first recorded incidence of dicephalia in a bull shark Carcharhinus leucas is reported from a foetus collected by a fisherman in the Gulf of Mexico near Florida, U.S.A. External examination, Radiography and magnetic resonance imaging revealed a case of monosomic dicephalia where the axial skeleton and internal organs were found to divide into parallel systems anterior to the pectoral girdle resulting in two well-developed heads. [ABSTRACT FROM AUTHOR]

The article focuses on the mortality rate of neonate bull sharks Carcharhinus leucas living in a south Florida estuary. In the authors' study, they found variation in the estimates of natural, fishing and total mortality during the span of the examination, but it provided a different survival rate of 77% that was able to reach beyond 18 months. They also observed that mortality rates of C. leucas were lower compared to that of other juvenile sharks. They conclude that the survival can be improved with the use of estuarine regions.

Carcharhinus isodon (finetooth shark) is a migratory shark found in coastal waters of the southeastern United States and is well documented in the waters of north Florida in both the Gulf of Mexico and the Atlantic Ocean. The southernmost reports are from Lemon Bay (27°N), just north of Charlotte Harbor on the west coast and from Port Salerno (27°N) on the east coast. Four C. isodon were captured on bottom-set longline in Florida Bay, just north of 25°N latitude, during routine sampling for Pristis pectinata (smalltooth sawfish). These captures extend the southern range of C. isodon in Florida to approximately 25°N and increase the likelihood of exchange between the Atlantic and Gulf stocks. [ABSTRACT FROM AUTHOR]