Study of penculture of the common carp (Cyprinus carpio L.) fingerlings at the Gorgan Bay to the maturity stage (broodstock management)

The aim of present project is study on the possibilities of brood stock production from fingerlings in the penculture condition and the effect of density on it .this project was done during three years with two different treatment and three repetitions in the Gorgan Bay. First treatment with two fingerlings per square meter and the 2nd with four fingerlings per square meter in each pen.To carry out the project at first fingerlings were brought from breeding and recruitment centre –Sijeval (Kolmeh) and the stocked at the earthen pound with concentrated food .After that they were adaptated with brakish water between 7-10 days and transferred to Gorgan Bay for cultivation with average weight of 93.78±32.66 grams and 20.53±2.37 cm in length. It should be noted that 6 pens (which surrounded by nets in the water) were fixed using mast with 15-20 cm in diameter and 5.5 meter in length , Net mesh size was 16 mm with string number 33 of kapron.Feeding was done according to the program two times by giving concentrated food at the period of cultivation Physic -o -chemical factors were measured. biometery was done monthly at each pen and other fishes (unwanted) were observed at the same time. results indicate that in the 1st and 2nd treatments average survival rate was 52.3 and 41 percent respectively with average weight of 410±64.98 grams and 390±52.8 and 28.3±1.79 cm and 27.66±1.57in length. SPSS used to analysethe data such as average length and weight of fish in the treatments and in different months with ANOVA method (p≤ 0.05) . results show that there is no significant difference between treatments. Autopsy observation also showed that fishes (female and male) are mature and histological studies showed that most of observed eggs are entirely mature with 800-1200 micron diameter gonad ( male) were mature at the pen in the Gorgan Bay condition .The male and female hormones were evaluated. 17-B- Estradiol and 11-keto testosterone hormones for adult fish (female and male) parents respectively are similar in dense with those adult fish before injection to use at the artificial breeding. Maturation were verified by autopsy, histology and hormone studies.