A STUDY ON POPULATION GENETIC OF HILSA SHAD, TENUALOSA ILISHA, IN KHOOZESTAN, IRAN USING MOLECULAR METHOD (RAPD)

The genetic structure of Hilsa Shad Tenualosa ilisha in Khouzestan waters including Karoon, Arvandrood and Bahmanshir Rivers as well as Persian Gl1lfwas studied using RAPD technique. After optimizing PCR condition, nine RAPD primers were selected from which 58 polymorphic loci were obtained on 12 specimens from each geographical region (A total of 48 specimens). RAPDPLOT, RAPDDIST and PDPGENE computer software were used to analyze the RAPD data. Canonical discriminant analysis was deployed for statistical assessment of the RAPD data. Maximum and minimum genetic distances were found between samples from Arvandrood River and Persian Gulf (0.1987) and Arvandrood and Bahmanshir Rivers (0.0852), respectively. The UPGMA dendrogram showed that the samples from Karoon River and Persian Gulf form one group and samples from Arvandrood and Bahmanshir Rivers form another suggesting the hypothesis that there are Iranian and Iraqi populations of the species that chose their own specific rivers for spawning. According to this hypothesis, the specimens from Persian Gulf chose Karoon as their spawning river. Other populations migrate to Tigris and Euphrates Rivers in Iraq. The canonical discriminant analysis of the RAPD data indicates that samples from the four geographical regions are statistically different from each other and high correlation was found for within region data (P<0.01). This suggests that Tenualosa ilisha is a schooling species. According to the hypotheses and considering the distribution of specimens in phylogenetic tree, it is concluded that Bahmanshir River is a specific pathway for the Iranian population fish heading towards Karoon River for spawning. The Iraqi population of the fish uses both Bahmanshir and Arvandrood Rivers to reach Shat-Al-Arab with Arvandrood being a specific route for the population. To verify these hypotheses further studies are needed.