The Biology reproduction of Rocha (Rutilus rutilus caspicus ) in the waters of Gomishan and Assurade Islands (South east of the Caspian Sea)

  This research was carried out with the aim of investigating the biological reproduction of fish retrieval in the Caspian Sea. Each Month catches were carried from Golestan province from December 2015 to September 2016. In total, 200 pieces of fish were caught to study reproductive production in the study area. In this research, the total length of the fish was 16.6 ± 1.5 mm and the frequency of weight was 89.7 ± 33.6 g. The maximum mean diameter of the egg was at the age of 4 years with the diameter of 1.17 ± 0.1 mm and the minimum diameter of the oocytes was 2 years old at 0.91 ± 0.15 mm. The GSI sexual health index varies from 0.09 to 0.19 for the female fish, and from the beginning of March and during the month of April we ham still the decrease. However, the spawning time began in late March and continued until mid-spring. Also, the mean absolute fecundity of the fish was 11,911.71 egg.The average maturity of 50% of the fish population was 138 mm and the mean age of puberty was 50% of the word of the word was equal to 125 mm. By examining the relationship between length and weight with Fecundity, there was a linear relationship between fork length and total weight with the Fecundity. The results of the Fecundity test with length and weight factors were found to be significant in Pearson test (P <0.05