The Reproductive Biology of Shirbot (Barbus grypus Heckel, 1843) in the Maroon River, Iran
Shirbot (Barbus grypus) is one of the species in south and southwest of Iran which is greatly favorable to residents of the region. Unfavorable ecological conditions in habitat of this species and overfishing have led to the reduction of the population of shirbot. Therefore, to restore the natural stock of this species, identifying its reproductive cycle associated with its habitat is of a great importance. In this study, the reproductive status of shirbot in the Maroon River in Khuzestan Province was studied in six sampling steps during four seasons. Also, morphological indicators, sex ratio, age of fish, gonadosomatic and hepatosomatic indices, histological changes in the testis and ovary of the fish were studied. The ratio of male fish to female was 2.35 to 1. The maximum value of gonadosomatic index (GSI) is among the specimens aged 3 to 5 years and in March and April. An increase of hepatosomatic index (HIS) during March may indicate the increased activity of liver during vitellogenesis and vitellogenin synthesis which is well verified by histological results of ovarian tissue. Based on our findings we recommend that the maximum reproductive activity of shirbot in the Maroon River starts around the end of March and continues to middle of July.