First record of the alien invasive species rotan (Perccottus glenii Dybowski, 1877) in Croatia

Abstract

Some 35 exotic fish species from various continents have been introduced into European freshwaters (Kottelat and Freyhof, 2007). A total of 15 exotic fish species now inhabit Croatian freshwaters (Mrakovcic et al., 2006). Furthermore, in the past 10 years, upstream expansion of an invasive alien species of goby (Neogobius sp.) has been noted in Croatian rivers of the Danube basin. Rotan (Perccottus glenii) is a species having no particular economic or sport value (Reshetnikov, 2003). It is a typical limnophilic species with high tolerance to extreme abiotic conditions (wide temperature oscillations and oxygen concentrations) that prefers still waters with well-developed aquatic vegetation and a silty substrate (Hegedis et al., 2007). Its tolerance, opportunism and aggressive behaviour make the rotan a perfect conqueror . This in turn represents a grave danger for the native amphibian and fish fauna in terms of predation, competition and disease transmission (Reshetnikov and Chibilev, 2009). The natural range of P. glenii comprises the far eastern part of Asia (Bogutskaya and Naseka, 2002). In the 20th century rotan was introduced on multiple occasions into various parts of Asia and eastern Europe. However, with its first appearance in the catchment of the Tisa River basin (Kosco et al., 2003; Hegedis et al., 2007), it was only a matter of time before it would spread to the Danube (Jurajda et al., 2006; Hegedis et al., 2007). At present there are no records of rotan in central and western Europe, although Andrzejewski and Mastynski (2004) speculated that P. glenii was likely already spreading unnoticed through western Europe. Nor did Freyhof (2003) exclude the assumption of its presence in the Odra River basin.