This paper describes the large-scale production of eggs and larvae of sea bass (Dicentrarchus labrax ) and shows how spawning can be planned to produce viable eggs throughout the year by manipulation of photoperiod and temperature. The rearing temperature was 9.5-22 degree C during spawning and 9-24 degree C during the gametogenesis. The photoperiodic cycles tested were normal (i.e. the photoperiodic cycle observed at Palavas-les-Flots, Mediterranean coast, France, 1984/1987) advanced by 3 to 5 months and delayed by 2 months.