effect of male age in caspian brown trout, salmo trutta broodstock on reproductive performance

in this study, three different age groups of male broodstocks (4, 5 and 6 years respectively) were used to fertilize eggs obtained from nine females. the results showed that 6 year old males had maximum body weight (1766 g), total length (56.3 cm) and sperm volume (31.83 ml). results did not show significant difference in spermatocrit and spermatozoa concentration among age groups (p>0.05). our study showed maximum fertilization rate (98.5 %), survival rate until eyes pigmentation (91.17 %), hatching rate (94.5 %) and survival rate until absorption of yolk sack (97.16 %) for 4 years treatment group. such positive relationships were detected between sperm production characteristics (spermatozoa concentration, spermatocrit and sperm volume) and fertilization parameters. based on our results, it can be concluded that 4 year old males have high efficiency leading to fertilization success.