For the first time for the Baikal Lake basin, evidence of the existence of populations of sculpin Cottus cf. poecilopus Heckel (alpine bullhead) characteristic of the adjacent Lena River basin in large northern Baikal tributaries, the Verkhnaya (Upper) Angara and the Kichera is provided. In June 2009 during the study of the lower reaches of the Kholodnaya River (Kichera-Baikal system), 8 individuals of sculpin aged from 3 to 5 years and in August 2009 5 more specimens aged from 4 to 6 were caught. All fish were fertile with the gonads in maturity stage III. In August 2010 33 individuals aged from 4 to 6 were collected in the main channel of the Upper Angara near Novy Uoyan settl.. At about the same time C.poecilopus was registered in stomachs of Arctic charr from Lake Amut (Churo-Upper Angara-Baikal system) near the divide with the Pravaya (Right) Mama (Mama-Vitim-Lena system). In August 2010 17 specimens aged from 1 to 4 were caught in the Upper Angara near the mouth of its large left tributary the Yanchui River. Sculpins from the rivers Kholodnaya, Upper Angara and Yanchui have higher growth rate as compared to the ones from mountain lakes of the upper Lena basin. About 90 % of males and females matured at the age of 3 years. Absolute fecundity of two females from the Upper Angara River was 149 and 556 (with a mean of 352,5) eggs and of two females from the Kholodnaya River, 223 and 305 (with a mean of 264) eggs. This exceeds the fecundity of sculpins from mountain lakes in the Lena part of Baikal rift zone, which averages less than 150 eggs. Sculpins spawn in the Kholodnaya River in the 1st half of June. The diet of C. cf. poecilopus all over the Baikal basin as well as in adjacent sites in the Lena basin was basically composed of larvae of amphibious insects (trichopterans, ephemeropterans, chironomids and plecopterans). The discovery of the third species from the Lena basin in the Baikal basin following the findings of Arctic charr Salvelinus alpinus and grayling Thymallus baicalolenensis evidences the absence of differences in the structure of ichthyofaunas of the upper parts of both neighboring basins. Sculpins permeate along the streams to mountain lakes more easily than other species and colonize the most elevated ones in lake cascades within the northern part of Baikal rift zone. Their dispersal across the divide could proceed in two ways: via headwater captures or via flattened passes between converging upper reaches of adjacent streams.
Sources and provenances for the Late Cenozoic sands of the Olhon Island (Baikal rift zone)