Geometric Morphometric Analysis of Alosa braschnikowi (Teleostei, Clupeidae) populations in the southern Caspian Sea

The aim of this study was to investigate body shape variations of Alosa braschnikowi populations in three localities of the Caspian Sea using geometric morphometric method. So that, 216 specimens were caught from three regions from west to east, including Guilan (Anzali), Mazandaran (Sari) and Golestan (Miankaleh). Shape data was extracted using 15 landmark points on 2-D pictures of specimens. The PCA, DFA analyses and cluster analysis based on Euclidean square distances were used to examine shape differences among the three populations. The results showed that there was a significant difference between the studied populations in terms of body shape (p<0.05). The population in Guilan had a longer head and snout, short and depth caudal peduncle and longer dorsal fin base that was different from the populations in Mazandaran and Golestan regions. Differences in head and snout shapes of the Guilan population with other populations, can be considered as a reflect of differences in feeding resources and selection of food items. Body shape differences may also be due to geographical distance and other environmental parameters. Specifications obtained on the basis of the body shape of A. braschnikowi can provide an identification key that is useful to distinguish species.