Diving Behavior of Female Loggerhead Turtles (Caretta caretta) During Their Internesting Interval and an Evaluation of the Risk of Boat Strikes

Abstract

New advantages in science and technology, such as time depth recorders (TDRs), have allowed researchers to study the dive behavior of sea turtles in their natural habitats. Observing dive behavior of internesting turtles has provided significant evidence on how to protect nesting turtles from human interactions. One source of anthropogenic mortality on marine turtles is boat strikes. Trend data from the Florida Sea Turtle Stranding Network demonstrate that the annual proportions of boat-strike related mortality is increasing. Since 1980 boat strike injuries have tripled in Florida. This study, near Casey Key Beach in southwest Florida, examined the internesting dive behavior of loggerhead sea turtles using time-depth-recorders; National Geographic Crittercamstm, and satellite-linked location data to evaluate the risk of boat impacts based on the resulting dive data. When combined with 4 years of satellite telemetry data gathered prior to this study I revealed that loggerhead turtles are most vulnerable to boat strikes between 8 a.m. – 12 p.m. on the day following a nesting or false crawl event and on the night before returning to the beach to nest. Potential mitigation measures, such as spatial and temporal boat restrictions, are reviewed by this study.