Introduction Among the Percids, Sander lucioperca (pikeperch) is an ecologically significant predatory fish species in the temperate waters of Eurasia and is of importance to fisheries (Popova and Sytina, 1976). The pikeperch inhabits Turkish inland waters and has a wide distribution, including Lake Marmara, Lake Beyşehir, Leke Eğirdir, and Hirfanlı Dam Lake (Balık and Geldiay, 2002; Apaydın Yağcı et al., 2014). The introduction of alien species to freshwater lakes goes back to the 1950s, when the first alien species, Gambusia sp., was introduced to many wetlands in Turkey (İnnal and Erkakan, 2006; Yerli et al., 2013). This was followed by another alien species, S. lucioperca, which was introduced for the first time to Lake Eğirdir in 1955 (Numann, 1958). After pikeperch was introduced to Lake Eğirdir, it has been reported that the fish fauna and annual fishing efficiency are constantly changing. While the annual amount of catch in the lake was 2000 tons/year in the 1970s, it decreased to 38-450 tons/year between 2008 and 2013. A total of 9 alien fish species (Sander lucioperca, Gambusia holbrooki, Knipowitschia caucasica, Tinca tinca, Carassius gibelio, Alburnus chalcoides, Seminemacheilus ispartensis, Atherina boyeri, and Pseudorasbora parva) were introduced to the lake between 1955 and 2010. Among these species, A. chalcoides and T. tinca were observed in the lake for a short period of time. Some native species have not been observed for a long time after the introduction of pikeperch to the lake. However, after the population of pikeperch decreased, some natural species have reappeared in the
