Study on population condition, gonadosomatic and hepatosomatic indices in three species of Alosa in the Southwestern coast of the Caspian Sea (Gilan provice)

In this study, hepatosomatic, gonadosomatic and condition of Alosa species were studied. A sampling were done from 5 stations (Rossdar, Clachay , Chaboksar, Chamkhala and Kiyoshahr) was arried out on the eastern coast of Gilan in 2016. A total of 693 sampling fish were collected. Samples were transferred to the laboratory in 10% formalin formaldehyde. Three species of Alosa namely Alosa.braschnikowi, A.caspia and A.Kessleri were identified, which were 354 samples (51.08%), 78 samples (25.3% 11%) and 261 individuals respectivetly (37.67%) were calculated.Fish were divide into 7 age classes (1 up to 7 years old), the highest percentage of A.braschnikowi population at age 3 (39.83%), A.caspia at age 4 (37.18%), and A.Kessleri species at age 4 (23 .40%). The highest mean (± standard error) in weight and length was observed in the A.braschnikowi species, which was 32.75 ± 05.027 grams and 38.39 ± 27.27 mm respectively. The lowest mean (± standard error) in weight and length was observed in A.caspia, which was 83.52 ± 53.13 and 11.32 ± 66.27 mm, respectively.In the three studied species of A.braschnikowi, A.caspia and A.Kessleri, the status index, gonadosomatic and hepatosomatic index (0.18 0.01, 0.12 ± 0.01 and 0.12, 0.01), (9.0 ± 0.04) 0.0 ± 0.06 and 0.77 ± 0/0) and (1.12 ± 0.0, 1.08 ± 0.04 and 1.2 ± 0.0), has no significant differences (p> 0.05). The sex ratio of the A.braschnikowi and A.Kessleri was 1: 1 (male: female), but in the A.caspia it was 1.33: 1.