Morphometric variation of the endangered Caspian lamprey, (Pisces: Petromyzontidae), from migrating stocks of two rivers along the southern Caspian Sea.

Background: Morphological studies on fishes are important from various viewpoints. Studies carried out on the Caspian Sea fishes show that many species possess speciation and population formation microprocess running. Morphologicalcharacteristics of the native endangered Caspian lamprey, Kessler1870, from migrating stocks of two major rivers in the southern Caspian Sea were analyzed to investigate the hypothesis population structure and morphologic sexual dimorphism.