Temporal characteristics of downstream migration of smolts of the European river lamprey Lampetra fluviatilis in the Chernaya River

Abstract

Data on the seasonal and diurnal dynamics of downstream migration of smolts of the European river lamprey Lampetra fluviatilis are obtained. On the basis of published data and surveys in nature, it is shown that in the largest part of the area the downstream migration of smolts occurs mainly in spring, in the period of high water in rivers caused by snow melting. The smolts undertake downstream migration at night, under minimal illumination. It has been determined experimentally that the smolts are characterized by negative photopreferendum (>90% of smolts preferred illumination <0.4 lx).