Morphological comparison of two shad species, Alosa braschnikowi and Alosa saposchnikowii using morphometric and meristic characteristics in Guilan coasts

This study was aimed to compare the morphological features of two shad species ofthe genus Alosa including Alosa braschnikowi and Alosa saposchnikowii on thesouthwestern coasts of Caspian Sea between fishing stations of the Chobar toKhumam in the Guilan Province. A total of 76 specimens (51 of A. braschnikowi and26 of A. saposchnikowii) were collected in 2014. Morphological features including10 meristic and 23 morphometric characteristics were compared between twospecies. The results of principal component analysis base on first and secondcomponents of the morphometric characteristics revealed that, posterior end of dorsalfin to caudal peduncle distance, head length, pectoral fin length and anal fin heightare different between two species and had theS Shighest rate of loadings. Therefore inA. braschnikowi, the distance between the posterior end of dorsal fin to anterior ofcaudal peduncle, distance between origins of ventral and anal fins, head length,pectoral fin hight and anal ratio of fin height to standard length were greater thatnthose of A. saposchnikowii. In meristic characteristics, significant differences(P<0.05) observed in pectoral fin soft rays and number of keel scales, but overlappingwere appeared in these two and other meristic characteristics.

Keywords:

Shads , Alosa saposchnikowii , Alosa braschnikowi , Caspian Sea