Preliminary stock structure assessment of the ladyfish Elops machnata (Forsskal, 1775) in south-east and south-west coasts of India by mitochondrial DNA control region sequence analysis

Elops machnata (Forsskal, 1775) is considered as least concern (LC) in the IUCN red list and the population trends is unknown in India. Mitochondrial DNA control region (CR) sequences were used to study the genetic status of this fish in Muthupettai, Parangipettai, Marakanam and Cochin estuaries in south India. The K2P genetic distance was high (0.22) between Cochin and Muthupettai populations. Parangipettai and Muthupettai populations are homogeneous and showed more FST value (1.000). There was a significant positive correlation of genetic distance in relation to the geographic distance (R2=0.235). There were a total of 8 haplotypes and Tajima's D test showed a mean value of 0.2579 +/- 0.4468 in the four populations. Analysis of molecular variance showed very less percentage of variation within population (5.30%) than variation among populations (15.02%; p = 1.000 +/- 0.000). Both Neighbour joining (NJ) tree and the minimum spanning network of haplotypes, clearly indicated two separate estuarine populations of the species in Tamil Nadu and Kerala. Mitochondrial CR here provides a contemporary evidence of partial restricted gene flow in E. machnata among the four populations. The population genetic structure of this species could further be studied using other molecular markers to provide additional data for effective management and conservation of the resource.