The study of some biological indices of Alosa four species in Caspian Sea coast (Mazandaran province)

Document Type : Research Paper



The objective of the present study was comparing some biological parameters including length, weight, age and sexuality of four species of genus Alosa (A. saposchnikowii, A. sapia, A. kessleri and A. braschnikowi) in coastal zone of Mazandaran province of the Caspian Sea. Monthly random samples were collected during October 2014 and April 2015 (249 samples). The highest total length (27.65±4.32cm) and body weight (262.05±172.25g) belonged to A. braschnikowi. There was a significant correlation between total length and body weight among four species of Alosa (P<0.001). Sex ratio (male:female) of four species were 1.35:1, 1.28:1, 1:1.4 and 2.38:1,  in respect to above mentioned order. Only the sex ratio of A. saposchnikowii (2.38:1) was significantly different from the expected 1:1 ratio (P<0.001). Gonadosomatic Index (GSI) among four species of Alosa was significantly different (P<0.05, F=4.04). Condition factor (CF) between four species of Alosa showed a significant difference (P<0.05, F=4.26). The results showed environmental compatibility of A. braschnikowi was better than other species.