Leningrad Oblast of two great lakes of the European Part of Russia, Lake Ladoga and Lake Onega. Its northeastern part, between the Gulf of Finland and Lake Ladoga, occupies the Karelian Isthmus. Some islands in the Gulf of Finland (including Kotlin, on which the city of Kronstadt has been built) and Lake Ladoga (including Konevets) also belong to the oblast. Much of the area of the oblast belongs to the drainage basin of the Neva, which is the only outflow of Lake Ladoga. Whereas the Neva, which flows to the Gulf of Finland (the city of Saint Petersburg is located in its
Lake Ladoga Finland, between 4,000 and 2,000 BP. Dating of some sediments in the northwestern part of Lake Ladoga suggests it happened at 3,100 radiocarbon years BP (3,410–3,250 calendar years BP). The Ladoga is rich with fish. 48 forms (species and infra specific taxa) of fish have been encountered in the lake, including roach, carp bream, zander, European perch, ruffe, endemic variety of smelt, two varieties of "Coregonus albula" (vendace), eight varieties of "Coregonus lavaretus", a number of other "Salmonidae" as well as, albeit rarely, endangered European sea sturgeon. Commercial fishing was once a major industry but has been hurt by overfishing.