مشخصات پژوهش

Morphological studies are strong and instrumental for determining discreteness of the similar species and extensively used to identify differences between fish populations. A total of 216 specimens of Alosa braschnikowi were randomly collected by beach seine from three fishing regions along the southern Caspian Sea coasts, including some regions of Miankaleh, Sari and Anzali, in the fishing season during 2018-2019. The extracted landmark-points (body shape data) were submitted to a generalized Procrustes analysis (GPA) to remove nonshape data in PAST software. In the present study, the size effect was removed successfully by procrustes action in PAST software. Principal component analysis (PCA) was performed to summarize the variation among the specimens as few dimensions as possible. As a complement to discriminant analysis, morphometric distances among the three localities were inferred to cluster analysis by adopting the Euclidean square distance as a measure of dissimilarity method as the clustering algorithm. The dendrogram derived from cluster analysis of Euclidean square distances showed that the three populations of A. braschnikowi were distinct from each other in terms of morphometric characters. The Wilks’ lambda tests of discriminant analysis indicated significant differences in morphometric characters of the three populations. The results of the present study demonstrated significant morphological differences between the three populations of A. braschnikowi. These differences in the three studied basins were mainly related to the characteristics of head and snout, body height, caudal peduncle, dorsal and anal fin base, which could be related to the hydraulic conditions and diet of the populations.