THE DISTRIBUTION OF LOGGERHEAD TURTLES (CARETTA-CARETTA) IN THE ENTRANCE CHANNEL OF CHARLESTON HARBOR, SOUTH-CAROLINA, USA

A 16-month survey of sea turtle populations was conducted in the entra nce channel of Charleston Harbor in order to document the seasonal, di urnal and spatial variability in turtle densities within a portion of the channel that required dredging using hopper dredges. Fifty-three l oggerhead turtles (Caretta caretta), and one Kemp's ridley turtle (Lep idochelys kempi) were captured, tagged and released during the survey period. Loggerhead turtle densities varied seasonally with highest den sities observed during the summer months and lower densities observed during the spring and fall. Densities were positively correlated with water temperature and no turtles were captured in winter months when w ater temperatures were below 16-degrees-C. The relative abundance of t urtles varied significantly among the four zones representing differen t segments of the channel length, but not among the subzones represent ing different portions of the channel width. Highest densities were co llected from a zone which contained both mud bottom and hard bottom ha bitats. Lowest densities wee found in the zone closest to the seaward end of the channel jetties. Over the entire study period, approximatel y 60% of the turtles were captured at night; however, there was no sig nificant difference in diel catch rates. Eight of the 53 loggerhead tu rtles collected in this study were recaptured specimens, and most of t hese turtles had been at large for several months. The study results s uggest that turtle mortalities can be reduced or eliminated if dredgin g is accomplished during the winter months, and that the probable inci dence of turtle entrainment will be greater in certain portions of the channel compared to others.