Vol. 54, 2015

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

Saber Vatandoust¹, Hamed Mousavi-Sabet^2,3*, Majid Razeghi-Mansour⁴, Hosein AnvariFar⁵ and Adeleh Heidari²

¹Department of Fisheries, Babol Branch, Islamic Azad University, Babol, Iran
²Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, P.O. Box 1144, Guilan, Iran
³The Caspian Sea Basin Research Center, University of Guilan, Rasht, Guilan, Iran
⁴Young Researchers and Elite Club, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran
⁵Department of Fisheries, Faculty of Animal Science and Fisheries, University of Agriculture and Natural Resources, Sari, Iran

Abstract
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. Morphological characteristics of the native endangered Caspian lamprey, Caspiomyzon wagneri Kessler 1870, from migrating stocks of two major rivers in the southern Caspian Sea were analyzed to investigate the hypothesispopulation structure and morphologic sexual dimorphism.
Results: Univariate analysis of variance of 180 adult specimens showed significant differences between the means of the two studied groups for 15 standardized morphometric measurements out of 31 (P < 0.05). In morphometric trait linear discriminant function analysis, the overall assignments of individuals into their original groups in male and female specimens were 77.1 and 84.0 %, respectively. The discriminant analysis showed a morphological segregation of the studied populations based on the characters predorsal length, interdorsal, interorbital distance, tail length, and first dorsal fin length. The principal component analysis, scatter plot of individual component score
between PC1 and PC2, showed the specimens grouped into two areas but with high and moderate overlap between two localities in males and females, respectively.
Conclusions: The present study indicated that there are at least two types of morphological forms of Caspian lamprey that had high morphometric differentiation in the rivers across the southern Caspian Sea, which can beconsidered in conservational policy of this valuable species.

Key words: Sexual dimorphism; Morphology; Population structure; Iran.

*Correspondence: E-mail: mousavi-sabet@guilan.ac.ir; mosavii.h@gmail.com