Range expansion of invasive fish (Perccottus glenii): the past, the present, and the future

Background/Question/Methods

I analyzed the invasion of the rotan, Perccottus glenii Dybowski, 1877 (family Odontobutidae), known also as Amur or Chinese sleeper, which is one of the most widespread invasive fish in Eurasia. Rotan is a medium-sized fish that is native to the Far East region of Eurasia. The rotan’s ability to effectively use trophic resources ranging from ciliates to vertebrates coupled with a prolonged reproductive period, likely allows the coexistence of individuals of multiple sizes. Rotan is able to escape competition and predation by inhabiting waterbodies unsuitable for most other freshwater fishes of Northern Eurasia. The above-mentioned biological characteristics are typical for highly invasive species. The history of its geographical distribution has been reconstructed by means of analysis of spatio-temporal dynamics using GIS and parasitological approach. The extent of the non-native range of rotan has been determined by analysis of peer reviewed journals and rare grey Russian-language literature, museum collections, specialist responses to a questionnaire and data of my four expeditions to West and East Siberia. These sources yielded more than 750 records of rotan.

Results/Conclusions

Since 1912 rotan has been transported by humans far outside its natural range several times during the 20^th century. At least 13 independent long-distant translocations and subsequent introductions were distinguished. Parasitological analysis allows us make conclusions concerning vectors of the invasion. Several new non-native sub-ranges were described, but some previously reported sub-ranges were considered unfounded. I prepared the point map of the current range of the fish under study. As far as I know, this is the first point map for Eurasian fish species. To date, invasive populations of rotan have been recorded in follow countries of Eurasia: Russia, Mongolia, Kazakhstan, Belarus, Ukraine, Lithuania, Latvia, Estonia, Poland, Slovakia, Hungary, Serbia, Bulgaria, Croatia, Romania, and Moldova. Species distribution models with independent validations showed that rotan distribution in Eurasia has climatic limitations; rotan have already invaded most areas with high climatic suitability in the Palearctic, but some regions of North Eurasia and North America, where rotan is currently absent, have high climatic suitability and may be vulnerable to invasion in the future. This is very important because rotan dramatically impacts native freshwater communities by depressing species diversity (e.g., extirpating some amphibian species).