The formation of today’s fish fauna in Karelian reservoirs began when a glacier, which covered the whole territory of Karelia during Quaternary period, had started to melt and move back to the northwest about 10-15 thousands years ago.
The fish settlement predominantly descended from the Baltic. Later, when the rivers Neva and Sviri were formed, the fish settlement in Karelian reservoirs continued through these rivers, so that fish penetrated into the southern and central parts of Karelia.
The reservoirs of northern Karelia were mainly occupied with fauna of the basin of the northern part of the bay Botnicheskiy in the Baltic Sea. From there fish could penetrate into lakes of Karelia by connected earlier, during post-glacial period, rivers’ and lakes’ systems of the Botnichesko-Belomorskiy isthmus. That’s why the lakes that today belong to the basin of the White Sea, have multiplicity of the Baltic white-fish and smelt.
The lakes of Karelia were also settled by the Arctic fauna. A Siberian whitefish penetrated into the White Sea. In a number of Karelian lakes this specie formed local inhabited areas. Smelt, dwelling along a coastline of the White Sea and moving into rivers for spawning, also belongs to the Arctic subspecies of this fish. Some lakes are occupied with these fish, which combine features of both the Baltic and Arctic ones. This means that in the past the reservoirs had conditions for settlement of fish belonging to both basins of the seas, and that’s why a fish mixing occurred.
Lake Onego and Lake Segozero are notable for a goby that is related to the Belomorskiy goby. This species as relic Crustaceans remained in the lakes from the times when Onego and Segozero were connected with the White Sea. The goby also dwells in Ladoga, but here the species has more similarity with the goby of the Baltic Sea.
During interglacial and post-glacial ages the climate was much warmer than it is today. At that time a migration of heat-loving fish to the north took place. Today’s rare specimen of Karelian lakes such as chub, rudd, gudgeon, cat-fish and some others are the migrators from the southern reservoirs. These fish could penetrate into the lakes of Karelia not only from the basin of the Baltic Sea (through Ladoga), but also from the basin of the Upper Volga, in particular through early-existed connection Sheksna – Kovzsha.
Probably, the same origin has a starlet, the image of which made by a Neolithic man (about 5,000 years ago) had still remained on the rock, near the cape Besov Nos (on the eastern side of Onego). Today, unfortunately, there are no sturgeons in Lake Onego. The starlet that sometimes is caught in the Shuya River and Petrozavodsk bay was brought in 1954 from Severnya Dvina.
Thus, today’s fauna of freshwater fish in Karelia was formed by settlement of fish peculiar to the basins of three areas: the Baltic and the Caspian Seas (the Upper Volga), and the Artic Ocean. The main feature of Karelian water fauna is abundance of salmons, which is the unique value of fishing industry in Karelia.
