Presence of the introduced Eurasian Ruffe (Gymnocephalus cernuus) in Mandra water reservoir (Burgas, Southeastern Bulgaria)

In the present study, we report on the Eurasian Ruffe (Gymnocephalus cernuus) in the Mandra Lake at City of Burgas. This is the only water basin in southeastern Bulgaria that is known to be inhabited by the species. The Eurasian Ruffe was detected in Mandra Lake for the first time in 1998; since then, there has been no information concerning the local population. We captured two adult G. cernuus in the winter of 2020 and propose these specimens represent a permanent viable population. In this study, we report the first specimens registered by professional biologists, thus confirming the data acquired by sports fishermen over the years.