Genetic analysis of sterlet (Acipenser ruthenus L.) populations in the Middle and Lower Danube sections

Sterlet populations have experienced a decline during the 20th century throughout its range, mainly due to poorly regulated fisheries, pollution, habitat fragmentation and habitat loss. They still represent a species of significant economic importance in the Middle and Lower Danube, so the present study was designed to investigate genetic diversity of wild sterlet populations from the Middle and Lower Danube and Lower Tisza rivers, as a prerequisite for their effective conservation and management. By applying ten microsatellite loci, we determined that pair-wise FST values were particularly low (0.018-0.038), indicating the presence of a gene flow and a low level of sub-structuring among the assessed locations. This trend can be also observed in allele sharing distance based NJ tree. Genetic variance could be attributed almost entirely to individuals, with no detectable strong population structure. Our analysis revealed considerable variation in the detection of a genetic bottleneck. Point estimate methods revealed different effective population sizes, with the lowest value being 8.1. Our study indicated the need for a careful planning of sterlet stocking programmes.