Characteristic of Hard to Identify Genus Acipenser Species in the Irtysh River

Abstract

In the summer period (June-July) of 2018 on the Irtysh river (the Tobolsk region) in the control catches of sterlet there were found specimens with pronounced differences from individuals inhabiting this water area. Differences were found in the form of bone plates and linear-weight characteristics. Later, local fishermen reported on many cases of specimens having the above differences. Reports about the similar species came from the Uvat region. In order to establish the belonging of these individuals to a particular family there have been investigated meristic features which are considered diagnostic for sturgeon species, as well as for hybrids. In the result of the study there was made a conclusion about belonging of these specimens to the genus Acipenser and, most likely, to the sterlet species.