The effects of an artificial and a natural diet on growth, survival and reproductive performance of wild caught and reared brill (Scophthalmus rhombus)

During this research, the effects of two diets were tested on growth, survival and reproductive performance of wild caught and laboratory reared (F1) Scophthalmus rhombus. A total of 80 adult brill (502 ± 19 g) were randomly distributed in a flow-through system composed by 8 tanks of 4.2 m2 (5.0 m3 × 1.2 m water depth). Four tanks were stocked with 10 animals each and fed ad libitum with frozen squid (Loligo gahi), while the remaining four tanks were stocked with 10 animals each and fed ad libitum with dry pellets (Vitalis repro®, from Skretting, Spain). Each replicate was stocked with 5 wild caught brill and 5 laboratory cultured brill. The experiment lasted for approximately one year (350 days). Origin of animals affected growth, with wild caught brill growing faster than F1. Sex also affected growth, with females attaining larger sizes than males. Diets only promoted differences in the months prior to reproduction, with animals fed dry pellets growing larger during these months. Only wild caught females matured. Among these, the ones fed with frozen squid showed higher reproductive potential, with more spawning females during a larger period of time. Neither diets or animal origin promoted differences on male reproductive potential. Different diets did promote differences in egg lipid composition.