Underwater observations on the bioecology of Carcharhinus plumbeus (Nardo, 1827) inhabitting Boncuk Bay (Gökova Gulf)

In this study, underwater observations were carried out regarding the bioecology of sandbar sharks, Carcharhinus plumbeus (Nardo, 1827), inhabiting Boncuk Bay (Gökova Gulf). Field works consisted of 100 skin divings conducted within a period of 39 days (April: 4 days; May: 9 days; June: 17 days; August: 4 days, September: 5 days) during 2009. In situ observations were made at the northern section of the bay, which includes several different habitat types, such as hard bottoms with gravel and stones, rocky substrates and seagrass meadows. The surface water temperatures were measured to range between 17,8 ? 21,5°C (mean, 19,3°C) on April, 18,4 ? 25,5°C (mean, 22,0°C) on May, 22,0 ? 27,0°C (mean, 25,2°C) on June, 26,7 ? 28,7°C (mean, 27,6°C) on August and 24,6 ? 26,2°C (mean, 25,4°C) on September. No sandbar sharks could be observed during 43 skin dives, while the remaining 57 dives have resulted with 99 times of shark observations, indicating the presence of a total of 296 individuals, either solitarily or in small schools.Key words: Carcharhinus plumbeus, Carcharhinidae, Boncuk Bay, Gökova Gulf, Bioecology