Dynamics of species composition of fish and some results of ichthyomonitoring in the middle course of the Oka (Ryazan oblast)

Changes in the structure of ichthyofauna in water bodies of Kaluga oblast over the past few decades

“…After the construction of the dams, the monkey goby was first recorded in the Volgograd Reservoir (1975), then in the Saratov and Gorky Res ervoirs (2002) (Atlas presnovodnykh…, 2002;Ryby v zapovednikakh…, 2010). During the past few years, spread even farther up the Volga and was recorded in Ryazan oblast (Ivancheva and Ivanchev, 2008;Ivanchev and Ivancheva, 2010). This species came to water bodies of Belarus as early as the 19th century along the Dnieper system (Zhukov, 2003).…”

“…However, it was never found in the Upper or Lower Volga basin until 1994, when it was first recorded in the Ivankovo Reservoir (Upper Volga basin) (Annotated catalog…, 1998;Slyn'ko et al, 2000;Yakovlev et al, 2001;Atlas presnovodnykh…, 2002 Slyn'ko andKiyashko, 2003); in the early 2000s, it appeared in small and large rivers of Kaluga oblast, and since then its abundance has been constantly increasing (Korolev andReshetnikov, 2005, 2008). In Ryazan oblast, its abundance has been increasing since 2002 (Ivancheva and Ivanchev, 2008;Ivanchev and Ivancheva 2010). Synchronous increases in its abundance have also been recorded in many neighbor ing regions Korolev and Resh etnikov, 2008).…”

“…It lives in the said segment of the river sympatrically with the common gudgeon, and the abundance of both species is rather high. In the Middle Oka, it has been recorded in Ryazan oblast (Ivancheva and Ivanchev, 2008). We collected several specimens in 2006 in the Bolva River (Dnieper basin in Kaluga oblast).…”