Genetic isolation among populations of the landlocked freshwater shrimp Macrobrachium yui in the Mekong River basin

The landlocked freshwater shrimp Macrobrachium yui has a high economic value for the rural villages in the northern area of Laos. In order to manage shrimp stock, we investigated genetic stock identification and genetic diversity of this shrimp in the Mekong and Ma River basins using mitochondrial DNA control region sequences. In total, 570 nucleotide sequences were obtained from 355 specimens at seven sampling sites of tributaries of the Xuang River, Ou River, Khan River and Houng River from the Mekong River basin and the Et River from the Ma River basin, in which 58 variable sites and 74 haplotypes were identified. Only Et River has low value in haplotypes and nucleotide diversities. Mismatch distribution analyses was used to evaluate possible historical events of population growth and decline. Minimum spanning tree was separated into the major two clades among localities. Pairwise Fst values showed strongly significant genetic differences and these indicate that this species has a restricted migration and gene flow among the rivers. For sustainable shrimp management we propose to ban stocking the shrimp from different river population to avoid genetic contamination and to conduct stock management of the shrimp independently for each river