Seyed Javad Hosseini

Salmo trutta caspius is a valuable endemic species in the Caspian Sea. There are two migrating forms of spring and fall run with different appearance characteristics. AFLP molecular markers were used to evaluate the possibility of identification of fall and spring migrating Caspian trout. 12 different EcoRI / MseI primer combinations were used, from which a total of 807 bands were produced that 227 of them were polymorphic loci. Perce ntage of polymorphism loci in spring - run (85.02%) was higher than fall - run (76.21%). The obtained results regarding mean heterozygosity did not show significant differences between fall - run and spring -run Caspian trout. Nei’s genetic distance was 0.034% an d the variance between and within two populations were 6% and 94%, respectively. The results show that the genetic variation between fall and spring migrating Caspian trout is not significant. Therefore, spring forms are probably a part of Fall - run populat ion and the difference could be attributed to physiology, environment or other related factors.