Influence of age of female gilthead seabream (Sparus aurata L.) broodstock on spawning quality throughout the reproductive season

The present study aimed to evaluate the influence of age of female gilthead seabream (Sparus aurata L.) broodstock on spawning quality parameters including egg lipid composition throughout the reproductive season (early, mid- and late seasons). Eggs were obtained from four groups of fish consisting of 3-, 4-, 5- and 6-year-old females (average weight of 1.3, 1.5, 2.3 and 2.8 kg respectively) maintained in separate tanks together with a number of two-year-old males. The results showed higher relative fecundity and fertilization rates in 3-year-old female eggs compared to other age groups, indicating the influence of female age on these parameters. No significant differences were observed in hatching rate and yolk sac volume between the different age groups although egg diameter tended to increase with female age. The total lipid content of eggs was affected by the age factor, but this effect was dependent on the spawning season period. In the early season, eggs from younger females showed higher total lipid content than eggs from the other groups, while the opposite was observed in the mid- and late seasons. The effect of age was also highly significant in polar lipid fatty acid profile where eggs from younger females in the early season also showed higher contents of monoenes, total n-3 and n-3 HUFA fatty acids with respect to eggs from older females. There was a high positive correlation between DHA/EPA and AA/EPA ratios in both neutral and polar lipid versus hatching rate in 3, 4 and 5-year old females. However, the negative correlation of these parameters for 6-year-old females indicates the ambiguous importance of a proper balance between these essential fatty acids in embryonic development and egg hatching. Therefore, the results obtained show the need for more close investigation of this phenomenon in this species. In conclusion, under the environmental conditions of photoperiod and temperature assayed in this study, female gilthead seabream at maturity (3 years) were more fertile and showed better or at least equal egg quality parameters than older females.

► The effect of age of female Sparus aurata broodstock on spawning quality was studied.
► Eggs and larvae showed better or equal quality in younger than in older females.
► Relative fecundity and fertilization rate were higher for younger females.
► Hatching rate and yolk sac volume were not affected by female age.
► Total lipid and fatty acids of eggs were affected by female age and spawning season.