Investigation of relationship between some biological characteristics of female broodstocks with hatching, survival and early growth in rainbow trout (Oncorhynchus mykiss) larvae

In regarding to study the effect of biological parameters of female rainbow trout (Oncorhynchus mykiss</em>) brood stocks on girt, 30 specimen of rainbow trout brood stocks were selected from 3 different age class (3, 4, 5 years). The results showed, maximum of girt 36.35± 0.35cm , ovary weight 600±11.25 gr, hatching 90±4 % and larvae weight after hatching 0.15±0.01 were in 5 and 3 years old brood stocks, respectively. The results  showed significant  differences between 3,4 and 5 years old  brood stocks for this instances (P</em><0.05). Maximum of number of eggs in each gram 15±0. 26 Registered in 3 and 5 years old brood stocks, respectively. Maximum absolute fecundity, relative fecundity, and working fecundity were recorded in 4 and 3 years old brood stocks, respectively. The study pointed significant difference between investigated brood stocks (p<0.05). Maximum of larvae survival percentage were observed in 4 and 3 years old brood stocks, respectively. The results showed no significant difference between 5 and 3 years old brood stocks, but for 4 and 5 years old brood stocks was saw significant difference (P</em><0.05). Maximum of gonadosomatic index were observed in 5 and 3 years old brood stocks, respectively. Although gonadosomatic index between 4 and 5 years old fish showed no significant difference, but the study showed significant difference for 3 years old brood stocks (P</em><0.05).