In this study, we present data on the population of Western Caspian Turtle, Mauremys rivulata, from Gokceada (Imbros) located at the westernmost of Turkey. The species is distributed almost all around the island, particularly in the western part, with a very low density. Distribution of the species on the island was mapped and a total of 73 individuals were captured and marked in Buyukdere, the largest river of the island. Population size was estimated at 135 individuals (SE - 11, range - 117 - 161) and density was calculated as 68 ind/ha. Moreover, Emys orbicularis, another freshwater turtle species, which cohabits in the west Anatolia, was observed again on the island after 15 years. Tourism, creeks with irregular flow regime and holding water in the dams negatively affect populations of aquatic species, primarily M. rivulata on the island.